WO2002012553A2 - Verfahren zum nachweis von mutationen in nucleotidsequenzen - Google Patents
Verfahren zum nachweis von mutationen in nucleotidsequenzen Download PDFInfo
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- WO2002012553A2 WO2002012553A2 PCT/EP2001/008127 EP0108127W WO0212553A2 WO 2002012553 A2 WO2002012553 A2 WO 2002012553A2 EP 0108127 W EP0108127 W EP 0108127W WO 0212553 A2 WO0212553 A2 WO 0212553A2
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- C—CHEMISTRY; METALLURGY
- C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
- C12Q—MEASURING OR TESTING PROCESSES INVOLVING ENZYMES, NUCLEIC ACIDS OR MICROORGANISMS; COMPOSITIONS OR TEST PAPERS THEREFOR; PROCESSES OF PREPARING SUCH COMPOSITIONS; CONDITION-RESPONSIVE CONTROL IN MICROBIOLOGICAL OR ENZYMOLOGICAL PROCESSES
- C12Q1/00—Measuring or testing processes involving enzymes, nucleic acids or microorganisms; Compositions therefor; Processes of preparing such compositions
- C12Q1/68—Measuring or testing processes involving enzymes, nucleic acids or microorganisms; Compositions therefor; Processes of preparing such compositions involving nucleic acids
- C12Q1/6876—Nucleic acid products used in the analysis of nucleic acids, e.g. primers or probes
- C12Q1/6883—Nucleic acid products used in the analysis of nucleic acids, e.g. primers or probes for diseases caused by alterations of genetic material
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- C—CHEMISTRY; METALLURGY
- C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
- C12Q—MEASURING OR TESTING PROCESSES INVOLVING ENZYMES, NUCLEIC ACIDS OR MICROORGANISMS; COMPOSITIONS OR TEST PAPERS THEREFOR; PROCESSES OF PREPARING SUCH COMPOSITIONS; CONDITION-RESPONSIVE CONTROL IN MICROBIOLOGICAL OR ENZYMOLOGICAL PROCESSES
- C12Q2600/00—Oligonucleotides characterized by their use
- C12Q2600/156—Polymorphic or mutational markers
Definitions
- the present invention relates to a method with which mutations can be detected in parallel in different nucleotide sequences, the method also permitting the determination of the transcription rate of mutated and non-mutated nucleotide sequences.
- DNA sequences of most genes in the human organism are rewritten as protein sequences.
- the activity of a protein is determined in different individuals or cell types by several factors: First, the transcription activity of the respective gene determines how many copies of the protein are present in a cell.
- mutations can influence the activity of a protein. A reduced transcription rate or a repressing mutation lead to a decrease in protein activity (“loss-of-function"), while an increased transcription rate or one of the rarely occurring activating mutations lead to an increase in protein activity (“gain-of-function").
- Other factors, such as translation regulation and post-translational modifications, can also influence the activity of proteins.
- RNA detection such as.
- Hybridization is also made possible in a very short time by electronic addressing.
- Each of the usually 99 test electrodes of such a chip can be controlled individually; In contrast to other chip technologies, this allows the processing of several samples independently of one another.
- the methods described are suitable for the detection of nucleotide sequences in a sample, but mutation detection with high sample throughput is not possible with the methods described there alone.
- Point mutations single nucleotide polymorphisms, SNPs
- SNPs single nucleotide polymorphisms
- the resulting one Complex can either be detected directly (eg W09512688), indirectly (eg WO93 / 02216) or by a further enzymatic treatment (eg WO9529258), whereby the mutS protein can also be immobilized (WO9512689).
- the DNA heteroduplices are generated by passive hybridization in a suitable buffer system (e.g. C. Bellanne-Chantelot et al., Mutation Research 382, 35-43, (1997)).
- a suitable buffer system e.g. C. Bellanne-Chantelot et al., Mutation Research 382, 35-43, (1997).
- the heteroduplices of several genes, but not of several individuals can be generated on an array by passive hybridization (WO9906591). Passive hybridization of several sequences leads to more or less pronounced cross hybridizations. This inevitably results in base mismatches, which are then bound by mutS without one of the sequences involved having a mutation. This creates a high background, mutations are "covered”. So far, this problem has only been partially solved by using single-strand binding protein (SSB)
- SSB single-strand binding protein
- Expression strength of genes is possible. This is particularly important for individual examinations, e.g. B. for target validation and patient screening, advantageous.
- the invention is therefore based on the object of a method for the detection of
- Such a method could surprisingly be provided in the form of an array, whereby a parallelization of the hybridization reaction becomes possible.
- the object is achieved by a method for the detection of mutations in nucleotide sequences, in which single-stranded sample nucleotide sequences are hybridized with single-stranded reference nucleotide sequences, the single-stranded reference nucleotide sequences or single-stranded sample sequences being
- Nucleotide sequences before or during the hybridization or heteroduplexes from reference and sample nucleotide sequences after or during the hybridization are fixed in a spatially resolved manner on a support and the incubation is carried out with a substrate which detects heteroduplex mismatches, the substrate binding being able to be detected.
- a preferred method for detecting mutations in nucleotide sequences is
- the nucleotide sequence to be examined for mutations, which is complementary to the known nucleotide sequence, is also on the chip is applied and a heteroduplex is produced by hybridization of the two sequences, c) the heteroduplex is then incubated with a substrate which detects mismatches, preferably a marked substrate, and d) the mismatches are detected by detecting the one attached to them
- fixation of the single- or double-stranded nucleotide sequences and the hybridization can be electronically controlled, in particular electronically accelerated.
- a particularly preferred embodiment of the claimed method is characterized by a spatially resolved, electronically accelerated hybridization, the hybridization conditions, such as. B. the applied current, the applied voltage or the duration of electronic addressing can be set individually at the respective location.
- the base mismatch can then be detected simultaneously with or after the hybridization by adding a substrate that detects mismatches.
- known and unknown point mutations as well as insertion and deletion mutations can be identified quickly and easily. If mismatches occur between the fixed nucleotide sequence and the nucleotide sequence to be investigated, these will e.g. B. by marked
- Base mismatch-binding proteins or detected by electronic detection This makes it possible to read out the mismatches on the chip.
- Detectable mismatches represent e.g. B. the SNPs.
- the described method enables the parallel examination of several individuals for mutations on a chip.
- nucleotide sequence is used in connection with the description of the detection method according to the invention not only for deoxyribonucleic acid, but also for RNA or chemically modified polynucleotides, cDNA also falling under the term deoxyribonucleic acid;
- reference nucleotide sequence denotes a nucleotide sequence
- Sequence preferably a DNA sequence, which is used as a comparison sequence
- sample nucleotide sequence is a labeled nucleotide sequence, preferably a DNA sequence, which is to be checked for mutations;
- a “nucleotide chip” is characterized by a zoned chip surface to which sample or preferably reference nucleotide sequences are applied;
- Gene expression is the conversion of genetic information into RNA or protein.
- Electronic addressing is carried out by applying an electrical field, preferably between 1.5 V and 2.5 V with an addressing time between 1 and 3 Minutes. Due to the electrical charge of the nucleotide sequences to be addressed, their migration is greatly accelerated by applying an electric field. Addressing can take place in a spatially resolved manner, addressing different zones of the chip surface one after the other. Different addressing and
- Hybridization conditions can be set.
- nucleotide sequence heteroduplexes consisting of a predetermined nucleotide sequence, the reference
- Nucleotide sequence as well as the complementary nucleotide sequence from a physiological sample, the sample nucleotide sequence, generated on a chip surface. Mismatches that result indicate an SNP of the sample nucleotide sequence and can be detected by a substrate that binds to the defect. Base mismatch binding proteins are suitable for this.
- Base mismatch binding proteins can e.g. B. mutS or mutY, preferably from E. coli, T. thermophilus or T.aquaticus, MSH 1 to 6, preferably from S.cerevisiae, S1 nuclease, T4 endonuclease, thymine cosylase, cleavase or fusion proteins containing a domain of these base mismatches binding proteins.
- B. mutS or mutY preferably from E. coli, T. thermophilus or T.aquaticus
- MSH 1 to 6 preferably from S.cerevisiae, S1 nuclease, T4 endonuclease, thymine cosylase, cleavase or fusion proteins containing a domain of these base mismatches binding proteins.
- other proteins or substrates can also be used for this if they are able to specifically recognize and bind to a base mismatch in a nucleotide sequence duplex.
- the reference nucleotide sequence can be used as a biotinylated oligonucleotide, which is either synthesized or produced by amplification with sequence-specific oligonucleotides, one of which is biotinylated at the 5 'end.
- the reference nucleotide sequence is then converted into the single-stranded state by melting, preferably in a buffer solution with a low salt content, and applied to a predetermined position of a chip by electronic addressing.
- Suitable chips are marketed, for example, by Nanogen (San Diego / USA).
- the application of the reference nucleotide sequence can, for example, preferably by means of a Nanogen Molecular Biology Workstation using the parameters specified by the manufacturer. Unless stated otherwise, the chips or the Molecular Biology Workstation from Nanogen are used in accordance with the manual supplied, the use is also described in Radtkey et al., Nucl. Acids Res. 28, 2000, e17.
- sample nucleotide sequence which is complementary to the sequence already applied to the chip, can now be applied to the chip prepared in this way.
- dye-labeled oligonucleotides are synthesized or by amplification with sequence-specific oligonucleotides, one of which is at
- the dye-labeled nucleotide of the sample nucleotide sequence is the complementary counter strand to the biotinylated strand of the reference nucleotide sequence.
- the sample nucleotide sequence must also be melted beforehand, e.g. B. in a buffer solution with low salt content, converted into the single-stranded state and applied to the biotinylated reference nucleotide sequence by electronic addressing.
- Hybridization results in a nucleotide sequence heteroduplex consisting of reference nucleotide sequence and sample nucleotide sequence.
- the preparation of the heteroduplex can be done on an electronically addressable surface, e.g. B. with a Nanogen Molecular Biology
- Successful hybridization can e.g. B. optically followed by detection of the dye coupled to the heteroduplex and thereby determined quantitatively.
- sample nucleotide sequence can also be biotinylated and, as just described, electronically addressed. Hybridization in solution with subsequent electronic addressing is also possible, one of the two nucleotide sequences of the heteroduplex being biotinylated.
- other molecular sequences can also be used to fix nucleotide sequences
- mutS proteins from the mutS family are preferably used which recognize these mismatches with high specificity.
- the mispairing substrate is preferably added in excess, and unbound substrate can be removed by washing.
- the protein which recognizes mismatches can also contain polymeric markers (J. Biotechnol. 35, 165-189, 1994), metal markers, enzymatic or radioactive markings or quantum dots (Science Vol 281, 2016, Sep 25, 1998 ) contain.
- the enzyme label can z. B. a direct enzyme coupling or
- Chloramphenicol acetyl transferase, alkaline phosphatase, luciferase or peroxidase are particularly suitable for enzymatic labeling.
- substrate marking with dyes which absorb or emit light in the range between 400 and 800 nm is preferred.
- fluorescent dyes suitable for labeling are especially Cy TM 3, Cy TM 5 (from Amersham Pharmacia), Oregon Green 488, Alexa Fluor 488, Alexa Fluor 532, Alexa Fluor 546, Alexa Fluor 594, Alexa Fluor 647, Bodipy 558/568 , Bodipy 650/665, Bodipy 564/570 (e.g. from Mobitec, Germany), S 0535, S 0536 (e.g. from FEW, Germany), Dy-630-NHS, Dy-635 -NHS, EVOblue30-NHS (e.g.
- labeled antibodies can also be used which directly against mutS or against a fused peptide domain, such as. B. MBP are directed. If a mutS protein labeled with dye, for example, is then incubated with the heteroduplex nucleotide sequence bound to the chip surface, the protein preferably binds to the positions of the chip where mismatches within the heteroduplex have occurred. The bound dye-labeled mutS proteins can then by optical sensors, for. B. using the
- Nanogen Molecular Biology Workstation in connection with a suitable evaluation software can be determined quantitatively.
- the binding of the mismatch-detecting substrate can also be established using electrical methods such as B. cyclovoltametry or impedance spectrometry
- Microcantilever technology e.g. described in Science 288, 316-318, 2000
- detection using acoustic methods as described e.g. in WO 9743631
- gravimetric methods as described e.g. in WO 9743631
- the method according to the invention is not only suitable for the detection of
- Gene mutations may also indicate differences in the level of expression of the mRNA expressed in different cells or tissues.
- the mRNA is converted into cDNA, the cDNA obtained being used for the measurement.
- Detection is preferably carried out by dye which is coupled to the sample nucleotide sequence and is optically detected. Since the amount of dye at a given chip position correlates with the amount of mRNA or cDNA, the evaluation of the dye intensity of several chip positions allows differences in the level of expression different cells or tissues.
- the expression level of a gene can be determined in parallel in different samples or different genes. The parallel detection of mutations and gene expression differences in the same sample is not only time-saving, but also less prone to errors because of the uniform treatment of the samples in both detection systems.
- the substrate binding can also be detected by means of electrical methods. Impedance spectroscopy is particularly suitable for this, the change in the AC resistance at
- Measuring location is determined, which depends on the bound amount of substrate.
- a cyclic voltametric measurement of the voltage between an electron donor or acceptor bound to the nucleotide sequences and an electrically conductive surface is also conceivable, the electron flow being changed by the substrate binding.
- the electronic addressing takes place on a chip surface which is covered with a permeation layer.
- the permeation layer enables small ions to flow to the electrically conductive surface of the chip, thereby closing the circuit without the nucleotide sequences or the substrate coming into contact with the chip surface and being itself oxidized or reduced there.
- Suitable permeation layers are preferably non-ionic polymeric or gel-like materials which have a high permeability to nucleotide sequences and the substrate used, so that there is good penetration of the permeation layer during electronic addressing with the nucleotide sequences or during incubation with the mismatching substrate. So z. B.
- hydrogel coating Agarose coating of the electronically addressable chip is preferable.
- the hydrogel chip offers the advantages of higher sensitivity and better discrimination between mismatched and perfectly paired DNA compared to the agarose chip. This is surprising in that it could not have been foreseen that the nature of the permeation layer would have such a great influence on the
- the mismatch binding should take place at a salt concentration of 10 to 300 mM, preferably from 10 to 150 mM, and a salt concentration of 25 to 75 mM has been found to be particularly preferred.
- the optimal salt concentrations for mismatch detection by other substrates can be analogous to that
- Embodiment can be easily determined.
- the measuring accuracy of the method is increased by adding non-specific binding sites blocking substances such as. B. BSA increased.
- non-specific binding sites blocking substances such as. B. BSA increased.
- the addition of SSB can have a positive effect on the measurement accuracy, provided that single-stranded nucleic acid fragments are bound by the substrate used to identify mismatches, as described, for example, in B. is the case with mutS. If mutS was used as the substrate, however, only a slight improvement in the measurement accuracy could be achieved.
- Strand in which a cytosine residue has been mutated to thymine with an unmutated reference counter strand results in a GT mismatch that can be reliably detected with the help of the mutS protein from E. coli.
- other mutations can also be detected using the method presented here, in particular those point mutations which lead to a G: G, C: T or A: A mismatch when the mutated DNA hybridizes with the unmutated counter strand. Insertions or deletions of one or two bases can also be detected by mutS.
- the proportion of mutations that can be detected with the method described here can also be increased by hybridizing both strands of a DNA to be tested with the respective reference counter strand. This can be illustrated by the following example: A base exchange in which a guanine is replaced by cytosine, if it is not repaired, leads to the conversion of the original G: C base pair into a C: G base pair.
- both strands of a nucleotide sequence can be electronically hybridized separately locally or a mixture of both single strands is fixed on a chip surface.
- mutS from T.thermophilus has surprisingly proven to be particularly suitable.
- the method can also be adapted to the respective requirements by combining individual mismatches of recognizing substrates.
- the electronic addressing can e.g. B. on a chip on which the nucleotide sequences A, B, C, ..., N are already fixed at the locations a, b, c to n, with a mixture containing nucleotide sequences from the group A ' , B ⁇ C ⁇ ..., N ' take place.
- the nucleotide sequences A / A " to N / N ' each represent a reference and sample nucleotide sequence pair.
- Hybridization can e.g. B. by reversing the polarity of the electric field, the stringency of the hybridization conditions can be increased. This can be done in a location-specific manner and thus be individually adjustable for each location.
- sample nucleotide sequences A, B, C, ..., N When nucleotide sequences A, B, C, ..., N are attached, the hybridization takes place one after the other site-specifically with the samples A ⁇ B ⁇ C ⁇ ..., N ⁇ so that the heteroduplicates AA 'are located at location a, BB at location b, Can form CC at location c to NN ' at location n.
- the sample nucleotide sequences can also be attached to the chip surface and the successive electronically accelerated hybridization with the respective reference nucleotide sequences then takes place.
- the hybridization of sample nucleotide sequences of different origins, e.g. B. from different patients, always with the same reference nucleotide sequence is preferably carried out with the method scheme described.
- This embodiment of the method according to the invention is characterized by a high degree of reliability.
- the design of the measurements as a successive method is only possible by using an electronically addressable surface.
- the method according to the invention can thus be carried out in a highly parallelized manner on an electronically addressable surface; this enables a high sample throughput to be achieved.
- Another advantage of the claimed methods is that not only can the existence of a mutation be detected qualitatively, but also a quantitative determination of the transcription of the mutated nucleic acid sequence is possible.
- This is e.g. B. in the analysis of heterozygous genotypes of interest.
- the first is a measure of the transcription rate of the mutated nucleotide sequence Approximation of the amount of bound, specifically mismatching substrate. Standardization is helpful, especially for the quantitative determination of mutated nucleotide sequences.
- the reference or sample nucleotide sequence may be dye-labeled. It can be checked optically that the same amount of nucleotide sequences is fixed at the location of the standard measurement as at the location of the actual measurement.
- a completely complementary nucleotide sequence is then added in excess at the location of the standard measurement, so that all fixed nucleotide sequences are hybridized free of mismatches.
- additional additives such as BSA, SSB, detergents etc. are added. Recognizing after mismatching
- a comparison value can then be determined that serves as the standard.
- the mutated nucleotide sequence is also determined quantitatively in parallel with the addition of the mispairing substrate.
- the difference between the standard value and the measurement value enables a quantitative statement to be made about the transcription rate of the mutated nucleotide sequence.
- it makes sense to create a calibration curve with different concentrations of the mutated nucleotide sequence because e.g. B. the mutS binding to the heteroduplex does not increase linearly, but rather flattens with the number of base mismatches that occur.
- One reason for this can be mass transfer effects at the measurement location.
- the amount of DNA obtainable from it is generally limited. An excessive amplification would lead to the accumulation of mutated strands due to the error rate of the polymerase and thus to an increased background.
- fluctuations in the DNA concentration between different patient samples can be expected when using patient DNA. These fluctuations could cause fluctuations in the mutS signal and, in extreme cases, could prevent detection of the mutation.
- the method according to the invention in particular when using mutS as a substrate that detects mismatches, is also suitable for reliable and quantitative mutation detection even at low or fluctuating DNA concentrations. This is because relatively large fluctuations in the concentration of the DNA used do not lead to larger fluctuations in the mutS binding.
- the method according to the invention shows a high degree of reliability in the detection of mutations, especially in the range of practically relevant DNA concentrations, as obtained when examining samples from patients. Furthermore, the claimed method surprisingly shows a high level of insensitivity to fluctuations in the amount of nucleotide sequences prepared. This makes it possible to compare different patient samples even if the individual samples do not have exactly the same DNA concentration.
- the methods according to the invention are therefore suitable for the rapid and reliable detection of mutations.
- a large number of samples can be examined in parallel. This improves the genotypic screening for previously unknown mutations. So are z. B. in the course of the Human Genome Project large amounts of sequence data about the human genome, from which electronically addressable chips can be constructed that can be tested against sample nucleotide sequences from different people. This means that a large number of mutations can be quickly identified, which do not necessarily have to be expressed phenotypically.
- samples obtained from cells of a particular organism can be examined for the presence of a dominant or recessive inherited mutation.
- the possibility of large sample throughput allows screening for mutations in certain genes in a large group of people, e.g. B. on newborns.
- a disease disposition and the early treatment of inherited genetic defects such as. B. cystic fibrosis, Huntington's disease or sickle cell anemia, all of which are based on certain known mutations.
- any drug intolerance or drug ineffectiveness such as. B. a tamoxifen resistance, can be examined in a patient with such a method, as long as the incompatibility is correlated with a known mutation, or just a correlation can be generated by the analysis.
- kits contains an electronically addressable chip, reference nucleotide sequences which can be present in free form or already fixed to the chip surface and at least one substrate which specifically recognizes mismatches.
- the added reference nucleotide sequences have to be adapted to the intended use of the assay.
- MutS from E. coli is preferred as the substrate recognizing mismatches. But for special questions other substrates, such as. B. mutS from T.thermophilus for the detection of nucleotide insertions or deletions may be part of the kit.
- the present invention furthermore relates to a process for the preparation of protein-labeled mismatch-detecting proteins, an ester, preferably a succinimidyl ester, of the dye in a low concentration, preferably between 1 ⁇ M and 100 ⁇ M under mild conditions with a protein mismatch-detecting, preferably mutY , MSH1 to MSH6, S1 -
- Nuclease, T4 endonuclease, thyme glycolase or cleavase and particularly preferably with mutS is reacted with the exclusion of light. Furthermore, the use of a HEPES buffer consisting of 5 mM to 50 mM N-2-hydroxyethylpiperazine N'-2-ethanesulfonic acid (HEPES), pH 7.5 to 8.5, 50 to 500 mM KCI, 1 to 15 mM MgCl 2 , 5 to 15% glycerol in distilled water have been found to be advantageous.
- HEPES buffer consisting of 5 mM to 50 mM N-2-hydroxyethylpiperazine N'-2-ethanesulfonic acid (HEPES), pH 7.5 to 8.5, 50 to 500 mM KCI, 1 to 15 mM MgCl 2 , 5 to 15% glycerol in distilled water have been found to be advantageous.
- HEPES buffer consisting of 5 mM to
- mismatch-recognizing proteins can be marked directly with dyes, without the proteins being specific
- Another subject of the present invention is thus proteins which recognize mismatches, preferably mutY, MSH1 to MSH6, S1 -nuclease, T4-endonuclease, thymic glycolase or cleavase and particularly preferably mutS, which are dye-labeled.
- Dyes particularly suitable for marking are Cy TM 3, Cy TM 5, Oregon Green 488, Alexa Fluor 488, Alexa
- the invention also relates to mismatches
- Fusion proteins e.g. B. with an antibody binding epitope, such as. B. MBP, or with an enzymatic group, preferably with chloramphenicol acetyl transferase, alkaline phosphatase, luciferase or peroxidase, can be labeled.
- the label can also be a luminescent or radioactive group.
- Another object of the present invention is the use of mutS for a method for spatially resolved mutation detection in nucleotide sequences on a support, preferably on an electronically addressable surface.
- the use of directly fluorescence-labeled mutS is particularly advantageous here.
- Proteins of the mutS family which are known to be involved in the detection and repair of DNA damage in eukaryotes, bacteria and archeae play an important role (R. Fishel, Genes Dev. 12 (1998), 2096-2101). These proteins specifically bind to sections of DNA with base mismatches and initiate repair of the damage by recruiting enzymes.
- mutations are detected by electronically accelerated hybridization of the reference DNA with the DNA to be tested in connection with new, dye-labeled mutS proteins.
- a molecular biology workstation from Nanogen is used for this. Unless otherwise described in the exemplary embodiments, the measurements are carried out according to the manufacturer's instructions (manual for molecular biology
- Base mismatches of the resulting heteroduplexes reflect a mutation of the test DNA compared to the reference DNA and can e.g. B. localized by a dye-labeled mutS protein.
- the optical analysis of the chip then allows the assignment of a mutation to a gene fragment.
- mutS from E.coli, T. thermophilus, T.aquaticus or the fusion protein MBP-mutS were used, as indicated in each case.
- the dye-labeled mutS protein obtained was used in a further step for mutation detection in electronically addressed DNA heteroduplexes.
- nucleotide sequences used to construct the nucleotide chips are shown in the following list, including the respective markings.
- the DNA sequence encoding E. coli mutS was amplified by PCR and isolated by standard methods.
- the ⁇ '-primer (SEQ. ID No. 1) introduces a BamHI interface immediately before the start codon, while the 3'-primer (SEQ. ID No. 2) generates a HindIII interface after the stop codon.
- the PCR is known to the person skilled in the art and was carried out according to the following scheme:
- the mutS-PCR product (SEQ. ID. No. 3) is purified using a 1% TAE agarose gel and the desired DNA is extracted from a cut out agarose gel.
- the isolated DNA is quantified on a gel and cut with BamHI and Hindill.
- 10 ⁇ l mutS-PCR product (about 2 ⁇ g) with 30 U BamHI (3 ⁇ l, NEB, Heidelberg), 30 U Hindill (3 ⁇ l, NEB, Heidelberg), 6 ⁇ l 10x
- NEB2 buffer (NEB, Heidelberg), 0.6 ul 100 x BSA (NEB, Heidelberg) and 37.4 ul H 2 O combined and incubated at 37 ° C for 4 hours.
- the enzymes are then inactivated at 70 ° C for 10 minutes.
- the DNA is precipitated overnight at 4 ° C. after adding 6 ⁇ l Na acetate pH 4.9 and 165 ⁇ l ethanol. After washing the pellet in 70% ethanol, it is air dried.
- the DNA is taken up in 30 ⁇ l TE (10 mM TrisHCI, 1 mM EDTA, pH8).
- the E. coli expression plasmid pQE30 (SEQ. ID No. 4) (Qiagen, Hilden) is also cut with BamHI and HindIII.
- 10 ⁇ l pQE30 with 30 U BamHI (3 ⁇ l, NEB, Heidelberg) 30 U Hindlll (3 ⁇ l, NEB, Heidelberg)
- DNA is taken up in 30 ⁇ l TE (10 mM TrisHCI, 1 mM EDTA, pH8).
- pQE30 and mutS are compared on an agarose gel and 100 ng plasmid (2 ⁇ l) and 150 ng (5 ⁇ l) mutS DNA in a 20 ⁇ l ligation mixture with 2 ⁇ l 10 ⁇ ligase buffer (Röche, Mannheim), 2 ⁇ l ligase (2 U,
- a 5 ml LB (with 100 ⁇ g / ml ampicillin) overnight culture E.coli TOP10 with the plasmid pQE30-mutS is diluted so that in a subsequent 100 ml LB culture (100 ⁇ g / ml ampicillin) an OD595 of 0.05 arises.
- the cells are incubated at 37 ° C. with shaking (240 rpm) until an OD595 of 0.25 is reached.
- An IPTG concentration of 1 mM is then set in the culture and the cells are incubated for a further 4 hours.
- the cells are harvested by centrifugation (5,000 xg for 10 minutes).
- the cell pellet is taken up in 10 ml PBS buffer with 0.1 g lysozyme (Sigma, Deisendorf) and 250 U benzonase (Merck, Darmstadt) and incubated at 37 ° C. for 60 minutes.
- the material with bound mutS protein is separated off on a mini column with a glass frit (Biorad, Kunststoff) and washed three times with buffer A (4 ml, 2 ml, 2 ml). The protein is then eluted with 2 x 2 ml buffer B (Qiagen).
- the protocol developed by the company Pharmacia provides for optimal fluorescence labeling of the protein by incubating it with a large excess of fluorophore under relatively strongly basic conditions (0.1 M Na 2 CO 3 , pH 9.3).
- fluorescent labeling of the thermostable mutS from Thermus aquaticus was initially carried out using Cy TM 3.
- Cy TM 3 After gel permeation chromatography purification and subsequent SDS-PAGE analysis, a strongly fluorescent protein band could be detected, which clearly corresponds to a mutS protein labeled with Cy TM 3 due to its molecular weight (FIG. 3).
- Lane 1 shows the mutS-Cy TM 3 (T.aquaticus), while lanes 2 to 4 represent the mutS-Cy TM 5 (E. coli).
- Protein a refined and optimized labeling protocol must be established.
- the labeling reaction was carried out in a mixture (500 ⁇ l) of E. coli mutS protein (50 ⁇ g, 1.05 ⁇ M) with increasing concentrations of Cy TM 5-succinimidyl ester (12 ⁇ M, 20 ⁇ M, 50 ⁇ M and 100 ⁇ M) performed in labeling buffer at room temperature for 30 minutes in the dark.
- a NAP-5 gel filtration column (Pharmacia LKB Biotechnology, Uppsala, Sweden) was used with 3 column volumes of elution buffer (20 mM Tris-HCl pH 7.6, 150 mM KCI, 10 mM MgCI 2 , 0, 1mM EDTA, 1mM dithiothreitol (DTT), 10% glycerin in distilled water) equilibrated.
- the labeling reaction solution is mixed with elution buffer (500 ⁇ l), applied completely to the column and the differently fluorescence-labeled proteins are isolated by elution with elution buffer.
- the fluorescent protein fractions were then examined in more detail by UV spectroscopy (FIG. 4) and SDS-PAGE by gel chromatography (FIG. 5).
- the band-shift method was then used to check whether the mutS proteins conjugated with Cy TM 5 were functionally active, ie whether they were still specific could bind base mismatches.
- heteroduplices were obtained by hybridizing the oligonucleotides "AT” (Seq. ID No. 6) or “GT” (Seq. ID No. 7) with the oligonucleotide "sense” (Seq. ID No. 11) for 5 minutes Heating to 95 ° C in 10 M Tris-HCl, 100 mM KCI, 5 mM MgCI 2 followed by slow cooling to room temperature.
- the oligonucleotide "GT” faces this
- Oligonucleotide "AT” a mutation. Using the T4 polynucleotide kinase (New England Biolabs, Frankfurt), according to the manufacturer, 10 pmol of the two heteroduplexes produced with the oligonucleotides "AT” and “GT” were radioactive with 150 ⁇ Ci - 32 P-ATP at the 5 'ends marked and purified on Sephadex G50 gel filtration columns (Pharmacia, Uppsala, Sweden) according to the manufacturer's instructions.
- FIG. 6 shows Cy TM 5-conjugated E. coli mutS (lanes 4,9), which has no loss of activity compared to commercially available unlabeled protein (Gene Check, Fort Collins, USA, lanes 2, 7). The same applies to Cy TM 5-conjugated T. aquaticus mutS (Epicenter, Madison, USA, lanes 3, 8 unconjugated, lanes 5, 10 conjugated). Lanes 1 and 6 contain no protein. Conjugated and unconjugated proteins bound to the oligonucleotide with the
- Lanes 1 and 6 contain no protein.
- FIG. 8 shows E. coli lysates separated by SDS-PAGE from cultures transformed with pQE30-mutS, which were grown at different temperatures and overexpress mutS.
- the formation of inclusion bodies should be avoided by low incubation temperatures (30 ° C or 25 ° C).
- incubation temperatures (30 ° C or 25 ° C).
- mutS protein there are only very small amounts of mutS protein.
- a very large amount of mutS protein can be found in the insoluble fraction (inclusion bodies).
- Figure 8 shows a Coomassie stained 10% SDS-PAGE from E. coli lysates. Lane 1: insoluble, Lane 2 soluble fraction of 25 ° C cultures. Lane 3: insoluble, lane 4 soluble fraction of 30 ° C cultures. Lane 5: insoluble, Lane 6 soluble fraction of 37 ° C cultures. All cultures transformed with pQE30-mutS were induced and grown for 3 hours at the indicated temperatures with 0.3 mM IPTG.
- the DNA coding for mutS was inserted into the vector pMALc2x (NEB, Frankfurt, Seq. ID No. 8), from which the plasmid pMALc2x-mutS (Seq. ID. No. 9) resulted.
- Another advantage of this fusion protein over the conventional mutS protein is the commercial availability of anti-MBP antibodies, which allow detection of the fusion protein. An anti-mutS antibody is currently not commercially available.
- the fusion protein tested in this study consists of the 42 kDa maltose binding protein (MBP) and the 92 kDa mutS protein.
- the DNA sequence coding for mutS from E. coli was amplified by PCR and isolated according to standard methods.
- the 5 'primer BamHI (Seq. ID No. 52) introduces a BamHI interface before the start codon.
- the nucleotide sequence immediately in front of the start codon is mutated so that the start codon function is lost. This is to prevent the
- the 3 'primer HindIII rev (Seq. ID No. 2) introduces a HindIII interface after the stop codon.
- the PCR is known to the person skilled in the art and was carried out according to the following scheme: 4 ⁇ l genomic DNA from E. coli (prepared according to the manufacturer with the
- mutS-PCR product was then isolated using the PCR Purification Kit (Qiagen, Hilden, Germany) and freed from salts, primers and proteins.
- the isolated DNA is quantified on a gel and cut with BamHI and Hind ⁇ :
- 41 ⁇ l mutS-PCR product (about 2 ⁇ g) with 20 U BamHI (2 ⁇ l, NEB, Frankfurt) are 20 U Hindlll (2 ul, NEB, Frankfurt), 5 ul 10x NEB2 buffer (NEB, Frankfurt) combined and incubated at 37 ° C overnight.
- 10 ⁇ l of the vector pMALc2x (2 ⁇ g, from NEB, Frankfurt) are mixed with 20 U BamHI (2 ⁇ l,
- the amounts of pMALc2x and mutS are compared on an agarose gel and 200 ng plasmid (3 ⁇ l) and 400 ng (14 ⁇ l) mutS DNA in a 20 ⁇ l ligation mixture with 2 ⁇ l 10x ligase buffer (Röche, Mannheim) and 1 ⁇ l of T4DNA ligase (2 U, Röche, Mannheim) combined and incubated for 3 h at room temperature.
- the E.coli k12 strain "Goldstar" (Stratagene, La Jolla, San
- CaCI 2 , 50 mM MgCl 2 was taken up and incubated with 100 ⁇ l of the thawed bacteria for 20 min on ice. After a 10-minute incubation at room temperature, the bacteria were mixed with 1 ml LB medium and shaken for one Incubated at 37 ° C for one hour. The mixture was then spread on LB agar plates with 100 ⁇ g / ml ampicillin and incubated at 37 ° C. overnight. Individual clones were isolated and grown in 3 ml LB medium with 100 ⁇ g / ml ampicillin at 37 ° C. overnight.
- the MBP-mutS fusion protein was then purified by affinity chromatography on an amylose column and eluted in column buffer (see above) with 10mM maltose (described in: pMAL Protein Fusion and Purification System Handbook, NEB, Frankfurt). The protein concentration of the eluate was then determined using the Bradford Assay Kit (Biorad, Kunststoff). 2 ⁇ g of the eluate were
- the MBP-mutS fusion protein was mixed 1: 1 (v / v) with glycerin and stored at -20 ° C. The activity of the proteins was verified using the "band-shift" method and surface plasmon resonance technology (see below).
- 9A shows a Coomassie stained 5% -20% SDS-PAGE of E. coli lysates from pMALc2x-mutS transformed cells.
- Lane 1, 2 Kloni.
- Lane 3, 4 clone 4.
- Lane 5.6 clone 5.
- Lane 7.8 clone 6.
- the cells were not lysed prior to lysis (Lanel, 3,5,7) or with 0.3mM IPTG (Lane 2, 4,6,8).
- clones 1 and 6 a protein of the expected size of 140 kDa is formed (arrow).
- 9B Western blot analysis of a 5% -20% SDS-PAGE of E. coli lysates from pMALc2x-mutS transformed cells.
- Lane 1, 5 Kloni.
- Lane 2 6: clone 4. Lane 3.7: clone 5. Lane 4.8: clone 6. The cells were not induced before lysis (Lanel -4) or with 0.3 mM IPTG (Lane 5-8). In clones 1 and 6, a protein of the expected size of 140 kDa is recognized by the anti-MBP antibody (arrow). Clones 4 and 5 recognize a protein the size of MBP (approximately 40 kDa).
- Figure 9C Coomassie stained 5% -20% SDS-PAGE from purified MBP-mutS fusion proteins. MBP-mutS purified from affinity chromatography from 2 independent preparations was investigated by gel electrophoresis. Lane 1, marker. Lane 2:
- mutS protein (either an MBP-fused or an unfused variant, commercially available E. coli protein from Genescan (Fort Collins, USA), or mutS obtained from T. aquaticus from Biozym, Hess. Oldendorf) were dissolved in 18 mL 20 mM HEPES pH 7.9, 5 mM MgCl 2 , 150 mM KCI, 10% (v / v) glycerol. 250 nmoles of Cy TM 5-succinimidyl ester were dissolved in 2 ml of the same buffer, mixed well with the dissolved protein and incubated for 30 minutes at room temperature. Then the reactions with 2mL 20mM HEPES pH7.9, 5mM MgCl 2 , 150mM KCI, 100mM adenosine triphosphate, 10mM
- Dithiothreitol 10% (v / v) glycerin added.
- the protein-containing solutions were 2x for 3 hours and 1x overnight against 2L 20 mM Tris pH7.6, 5mM MgC, 150mM KCI, 1mM DTT, 10% (v / v) glycerol in a dialysis bag with a cut-off of 10 kDa dialyzed at 4 ° C.
- the protein was then mixed with 1 part by volume of glycerol and stored at ⁇ 20 ° C.
- FIG. 10 shows the loading of the 100-position chip with DNA by electronic addressing.
- the current strength per position fluctuated between 262 nA and 364 nA in rows 1-8, between 21 nA and 27 nA in rows 9 and 10, as a result of which less DNA was addressed at these positions (FIG. 10, left matrix, the two lower rows ).
- the oligonucleotide Seq which was completely complementary to the oligonucleotide "sense" (Seq. Id No. 10) and labeled with Cy TM 3 at the 5 ' end. ID No.
- rows 1 to 4 The slight fluctuations in the values in rows 1 to 4 as well as 7 and 8 indicate an even hybridization of the double-stranded oligonucleotides AT and GT.
- the comparably lower values of rows 9 and 10 reflect the smaller amounts of DNA in these rows due to lower addressing current strength (see above).
- the low values in row 5 represent the background signal, since no fluorescence-labeled DNA was addressed to this row.
- Row 6 contains only single-stranded DNA "sense" as a control.
- Proteins clearly shows that the protein binds preferentially to the oligonucleotide GT (Table 2). Even with very small amounts of DNA (Table 2, rows 9 and 10) it is possible to discriminate between the perfectly pairing oligonucleotide (AT) and the base mismatching oligonucleotide (GT) with the dye-labeled protein, which is possible with larger amounts of DNA (rows 1 - 4 as well as 7 and 8, see Table 1). The low background values are also striking (Table 2, rows 5 and 6). To determine if other base mismatch binding proteins such as e.g. The mutS protein from T aquaticus can also be used for the rapid detection of mutations on electronically addressable chips, initially became a 100 position chip from the company
- the low values in rows 5 and 6 represent the background signal, since no fluorescence-labeled DNA was addressed to these rows.
- the subsequent fluorescence measurement of the Cy TM 5-labeled T aquaticus mutS protein clearly shows that this protein also binds preferentially to the oligonucleotide GT (Table 4) and is therefore suitable for detecting mutations on electronically addressable DNA chips.
- Table 2 Determination of the fluorescence intensity of Cy TM 5-labeled E. coli mutS protein on an electronically addressed 100-position chip at 670 nm. The positions of the chip with the associated relative fluorescence intensities and the DNA addressed to these positions (outer right column ).
- Table 3 Determination of the fluorescence intensity of Cy 3 -labeled DNA on an electronically addressed 100 position chip at 575 nm. The positions of the chip with the associated relative fluorescence intensities as well as the DNA addressed to these positions (outer right column) are given.
- Table 4 Determination of the fluorescence intensity of Cy 5-labeled T. aquaticus mutS protein on an electronically addressed 100-position chip at 670 nm. The positions of the chip with the associated relative fluorescence intensities and the DNA addressed to these positions (outer right column) are given ,
- the binding conditions of the dye-labeled mutS protein were examined and optimized so that base mismatches on the surface of an electronically addressable chip can be recognized even better.
- two electronically addressable chips from Nanogen were first created, the surface of which consist of an agarose layer with embedded therein
- Streptavidin molecules exist, loaded with the biotinylated oligonucleotide "sense” (Seq. ID No. 10) and then with the Cy TM 3-labeled oligonucleotides "AT" (Seq. ID No. 12, counter strand for perfect base pairing) or GT (Seq ID No. 13, counter strand for GT base mismatch) hybridized.
- the mutS was then bound to the DNA double strands thus obtained in two different ways
- the oligonucleotides are first labeled with a Concentration of 100 nM dissolved in histidine buffer and incubated for 5 min at 95 ° C.
- the oligonucleotide "sense" was electronically addressed to defined positions of the two agarose chips in the charger of the Nanogen workstation for 60 seconds at a voltage of 2.0 V, the hybridization with the second strand oligonucleotides "AT" or GT for 120 seconds 2.0 V. The same for both chips
- Chip A One of the chips (hereinafter referred to as Chip A) was then filled with 0.5 ml
- Histidine buffer 50 mM L-histidine (Sigma, Deisenhofen); This solution was filtered through a membrane with a pore size of 0.2 ⁇ m and degassed by negative pressure.
- Phosphate block buffer 50 mM NaPO 4 , pH 7.4 / 500 mM NaCI / 3%
- Bovine serum albumin (BSA; from Serva, Heidelberg)
- High salt buffer 20 mM Tris, pH 7.6 / 300 mM KCI / 5 mM MgCI 2 / 0.01% Tween-20/1 mM DTT
- Table 5 Loading scheme for chips A and B; "AT”: perfect pairing, positions were addressed with sense and then hybridized with "AT”; GT: GT mismatch, positions were addressed with sense and then hybridized with GT; sense: single strand sense, positions were addressed with sense, but were not hybridized with any opposite strand; ss' ⁇ T “: single strand” AT “, positions were only loaded with” AT ", without biotinylated first strand.
- Table 8 Statistical evaluation of the results of Chip A and Chip B. The mean values and standard deviations of the fluorescence intensities of all positions with the same loading were calculated.
- Table 8 shows that the Eco // - MBP mutS under low salt conditions
- Base mismatches or insertions / deletions on DNA chips can be used.
- the following types of DNA double strands were generated on the various positions of an electronically addressable agarose chip from Nanogen by hybridization: - Completely complementary double strands
- Double strands containing one of the eight possible base mismatches (AA, AG, CA, CC, CT, GG, GT, TT)
- Double strands in which one strand contains an insertion of 1, 2 or 3 bases.
- the binding of E.co//-mutS to the DNA double strands thus obtained was then tested.
- the first and second strand oligonucleotides with a concentration of 100 nM were first dissolved in histidine buffer and denatured at 95 ° C. for 5 min.
- the electronic addressing of the biotinylated Oligonucleotides "sense" (Seq. ID No. 10) on the individual positions of the agarose chip were carried out in the charger of the Nanogen workstation for 60 seconds at a voltage of 2.0 V.
- the chip was removed from the charger, filled with 1 ml of block buffer and incubated for 60 min at room temperature to saturate unspecific protein binding sites. The chip was then incubated with 10 ⁇ l Cy TM 5-labeled Eco // mutS (concentration: 50 ng / ⁇ l) in 90 ⁇ l incubation buffer for 60 min at room temperature. After this incubation, the chip was hand-held
- Histidine buffer 50 mM L-histidine; this solution was through a membrane of
- Block buffer 20 mM Tris, pH 7.6 / 50 mM KCI / 5 mM MgCI 2 / 0.01% Tween-20/3%
- Incubation buffer 20 mM Tris, pH 7.6 / 50 mM KCI / 5 mM MgCI 2 / 0.01% Tween-20/1% BSA
- Wash buffer 20mM Tris, pH 7.6 / 50mM KCI / 5mM MgCl 2 / 0.1% Tween-20 -. - Different base mismatches.
- Neg. Positions not loaded with DNA.
- SsDNA positions loaded only with the single strand "sense”. All other positions were first addressed with the oligonucleotide "sense" and then hybridized with the second strand specified in the table.
- Table 11 Statistical evaluation of the results of the agarose chip with different base mismatches. The mean values and standard deviations of the fluorescence intensities of all positions with the same loading were calculated. In addition, the Quotient determined from the corresponding mean and the value obtained with perfectly paired DNA ("AT").
- Table 11 shows that the mean values of the fluorescence intensities for all mismatches and insertions tested are above the value obtained with the perfectly paired double strand.
- the GT mismatch is best bound by mutS; the fluorescence values measured at these positions are approximately 7 times higher than with the perfectly paired DNA.
- TT was only weakly recognized by mutS.
- insertions of one or two bases can also be detected with the method described here (FIG. 11).
- the loading of the hydrogel chip was carried out according to the protocol described in the example "Detection of different base mismatches by mutS", but both the addressing of the first strand oligonucleotide "sense" was carried out on the Hydrogel chip as well as the hybridization with the different second strands carried out at a voltage of 2.1 V.
- the loading scheme is given in Table 9.
- the loaded hydrogel chip was saturated with BSA, incubated with Cy TM 5-labeled Eco // mutS and washed according to the protocol given in the section "Detection of different base mismatches by mutS".
- the mutS protein bound to the individual positions was then determined by measuring the red fluorescence intensity was detected using the same device settings as for the measurement of the agarose chip ("high gain", integration time 256 ⁇ s).
- the measured relative fluorescence intensities are given in Table 12; the results of the statistical evaluation of the measurement data are shown in Table 13 and in FIG. 12.
- Table 13 Statistical evaluation of the results of the hydrogel chip with different mismatches. The mean values and standard deviations of the fluorescence intensities of all positions with the same loading were calculated. In addition, the quotient of the corresponding mean and the value obtained with perfectly paired DNA was determined for each mismatch.
- Figure 12 shows the binding of Cy TM 5-labeled Eco // mutS to mismatched DNA double strands generated by hybridization on an electronically addressable hydrogel chip. The mean red fluorescence intensity is shown with standard deviation for the different
- binding of the mutS proteins to various base mismatches was investigated using surface plasmon resonance technology. This was necessary to check whether all base mismatches were actually bound specifically by the proteins.
- the surface plasmon resonance technology allows a more precise quantification of the binding events.
- the "sense" (Seq. ID No. 11) biotinylated oligonucleotide at the 5 ' end and oligonucleotides partially complementary to this oligonucleotide (Seq. ID No. 12-22) (company Biospring, Frankfurt / Main) were synthesized.
- oligonucleotides Hybridizes against the oligonucleotide "sense" to form fully paired double-stranded DNA (AT), double-stranded DNA with a base mismatch (AA, AC, AG, CC, CT, GG, GT, TT) or double-stranded DNA with an insertion of 1, 2 or 3 thymidine residues (Table 14).
- oligonucleotides were taken up in buffer HBS-EP (10 mM HEPES pH 7.4, 150 mM NaCl, 3 mM EDTA, 0.005% (w / v) polysorbate 20, 5 mM MgCl 2 ) to a concentration of 2 pmol / ⁇ l.
- the oligonucleotide "sense" was then with a
- the oligonucleotides partially complementary to this oligonucleotide were applied under identical buffer conditions to the respective channels of the chip as in the example "Detection of point mutations by mutS on an electronically addressable hydrogel chip" in order to obtain the double-stranded DNA species shown in Table 14.
- the chip surface was equilibrated with 20 mM Tris-HCl pH 7.6, 50 mM KCI, 5 mM MgCI 2 , 0.01% Tween-20, 10% (v / v) glycerol.
- the MutS-maltose binding protein fusion protein labeled with Cy TM 5 was taken up in the same buffer at a concentration of 0.1 ⁇ g / ⁇ l and applied to the chip at a flow rate of 5 ⁇ l / min.
- the channels of the chip were then washed with 100 ⁇ l of the buffer 20 mM Tris-HCl pH 7.6, 50 mM KCI, 5 mM MgCl 2 , 0.01% Tween-20, 10% (v / v) glycerin rinsed, whereby non-specifically bound protein was washed away. After rinsing, the was -. double-stranded oligonucleotide bound protein amount (expressed as a resonance unit) determined (Table 14). It was shown that in addition to the CC base mismatch, in principle all base mismatches and insertions are better bound by the labeled fusion protein than the perfectly paired oligonucleotide "AT" (Table 14).
- the fluorescent dye-labeled mutS protein that we have designed and produced is therefore able to do so To locate any possible mutation
- the authors are not aware of any other fluorescent dye-labeled protein whose DNA-binding properties are retained after labeling, as is the case with the protein described here.
- FIG. 13 shows an exemplary sensogram of mutS binding.
- the change in mass over time (RU, resonance units) in the 4 channels of a Biacore SA chip is shown.
- the biotinylated oligonucleotide "sense" was applied to channels 1-4 and hybridized with the respective counter-strands to create a perfectly paired double strand ("AT", channel 4) or DNA with the base mismatches GT (channel 1), CC (channel 3 ) or GG (channel 2).
- Table 14 The binding of the MBP-mutS fusion protein to double-stranded oligonucleotides bound to the surface of Biacore TM SA chips with base mismatches (underlined bases) is shown.
- AT Seq. ID No. 12
- APC AT Seq. ID No. 25
- AT Seq. ID No. 28
- Brc AT Seq. ID No. 31
- Met AT Seq. ID No. 34
- MSH AT Seq. ID No. 37
- p53 AT Seq. ID No. 40
- Rb AT Seq. ID No. 43
- GT for GT mismatch: GT (Seq. ID No. 13), APC GT (Seq. ID No. 26), with GT (Seq. ID No. 29), Brc GT (Seq. ID No. 32), Met GT (Seq. ID No. 35), MSH GT
- the chips were removed from the charger, filled with 1 ml block buffer and more unsaturated for saturation Protein binding sites incubated for 60 min at room temperature. The chips were then incubated with 10 ⁇ l Cy TM 5-labeled Eco // mutS (concentration: 50 ng / ⁇ l) in 90 ⁇ l incubation buffer for 60 min at room temperature. After this incubation, the chips were washed by hand with 1 ml of incubation buffer, then inserted into the Nanogen reader and washed 70x with a 0.5 ml wash buffer at a temperature of 37 ° C. Finally, the Cy TM 5 and Cy TM 3 fluorescence intensities were measured on the individual positions of the chips in the Nanogen reader using the following device settings:
- Histidine buffer 50 mM L-histidine; this solution was through a membrane of
- Block buffer 20mM Tris, pH 7.6 / 50mM KCI / 5mM MgCI 2 / 0.01% Tween-20/3% BSA
- Incubation buffer 20 mM Tris, pH 7.6 / 50 mM KCI / 5 mM MgCI 2 / 0.01% Tween-20/1%
- BSA Wash buffer 20 mM Tris, pH 7.6 / 50 mM KCI / 5 mM MgCI 2 / 0.1% Tween-20
- the measured green fluorescence intensities are shown in Table 20 and the red fluorescence intensities in Table 21.
- the green fluorescence intensities were lower overall than with the agarose chip.
- the results of the statistical evaluation of the red fluorescence intensities are shown in Table 22 and in FIG. 15. The
- Chip position 9/6 was not included in the evaluation due to the very low green fluorescence.
- Table 15 Loading scheme of an agarose chip for the detection of the binding of Cy '5-labeled E. colimutS to GT base mismatches in different DNA double strands. Empty boxes do not symbolize positions loaded with DNA. All other positions were first addressed with the oligonucleotide mentioned in the top line and then hybridized with the second strand indicated in the bottom line.
- Table 16 Measurement of the green fluorescence intensity of an agarose chip for checking the loading with Cy TM 3-labeled second-strand oligonucleotides. The positions of the chip with the associated relative fluorescence intensities are indicated.
- Table 18 Statistical evaluation of the agarose chip with different, perfectly paired and GT mismatched DNA double strands. The mean values and standard deviations of the red fluorescence intensities of all positions with the same load were calculated. In addition, the quotient of the fluorescence after addition of the corresponding GT mismatching second strand and the fluorescence after addition of the completely complementary second strand was determined for each first strand. Positions 1/10, 2/4, 2/5, 2/6, 2/10 and 3/2 were not included in the evaluation due to their low green fluorescence.
- Table 19 Loading diagram of a hydrogel chip for the detection of the binding of Cy 5-labeled E colimutS to GT base mismatches in different DNA double strands. Empty boxes do not symbolize positions loaded with DNA. All other positions were first addressed with the oligonucleotide mentioned in the top line and then hybridized with the second strand indicated in the bottom line.
- Table 22 Statistical evaluation of the hydrogel chip with perfectly matched and GT mismatched DNA double strands. The mean values and standard deviations of the red fluorescence intensities of all positions with the same load were calculated. In addition, the quotient of the fluorescence after addition of the corresponding GT mismatching second strand and the fluorescence after addition of the completely complementary second strand was determined for each first strand. Position 9/6 was not included in the evaluation due to its low green fluorescence.
- DNA or cDNA is isolated from a human or animal tissue, not all strands isolated have the same nucleotide sequence. This may be due to the fact that the donor organism for a mutation is heterozygous (i.e. the mutation is only present on one of the two homologous chromosomes in each cell) or that only a part of the cells in the tissue have a specific mutation. This situation occurs particularly often in tumors because tumor cells are genetically unstable. When such an inhomogeneous patient DNA is hybridized with a reference DNA, a mixture of mismatched and perfectly paired double strands will then form.
- the first and second strand oligonucleotides were dissolved in histidine buffer (total concentration: 100 nM each) and denatured for 5 min at 95 ° C.
- the electronic addressing of the biotinylated oligonucleotides "sense" or p53 se to the individual positions of the agarose chip from Nanogen took place in the charger of the Nanogen workstation for 60 seconds at a voltage of 2.0 V.
- the hybridization with the various second-strand mixtures was carried out for 120 sec at 2.0 V.
- the loading scheme is shown in Table 23. After loading, the chip was removed from the charger with 1 ml
- Block buffer filled and incubated for saturation of non-specific protein binding sites for 60 min at room temperature.
- the chip was then incubated with 10 ⁇ l Cy TM 5-labeled E.co//-mutS (concentration: 50 ng / ⁇ l) in 90 ⁇ l incubation buffer for 60 min at room temperature. After this incubation, the chip was washed by hand with 1 ml of incubation buffer, then inserted into the Nanogen reader and washed 70 times with 0.5 ml of washing buffer at a temperature of 37 ° C. Finally, the Cy TM 5 fluorescence intensities were measured on the individual positions of the chip in the Nanogen reader with the following device settings: high Sensitivity ("high gain”); 256 ⁇ s integration time. The measured relative fluorescence intensities are given in Table 24; the results of the statistical evaluation of the measurement data are shown in Table 25 and in FIGS. 16A and 16B.
- Histidine buffer 50 mM L-histidine; this solution was through a membrane of
- Block buffer 20 mM Tris, pH 7.6 / 50 mM KCI / 5 mM MgCI 2 / 0.01% Tween-20/3%
- Incubation buffer 20 mM Tris, pH 7.6 / 50 mM KCI / 5 mM MgCI 2 / 0.01% Tween-20
- Wash buffer 20mM Tris, pH 7.6 / 50mM KCI / 5mM MgCl 2 / 0.1% Tween-20
- Table 23 Loading scheme of an agarose chip for the detection of the binding of Cy 5-labeled E colimutS to various mixtures of perfectly paired and GT-mismatched DNA double strands. Empty
- Boxes do not symbolize positions loaded with DNA (negative controls). Boxes with bold letters indicate positions that were only loaded with a DNA strand (single strand controls). All other positions were first addressed with the biotinylated oligonucleotide mentioned in the top line and then hybridized with the second-strand mixture indicated in the second line. As an additional check, the positions marked with italics were loaded with a combination of first strand and a non-complementary second strand; hybridization should not occur here.
- Table 24 Measurement of the red fluorescence intensity of an agarose chip for the detection of the binding of Cy 1M 5-labeled? .Co / z ' -nutS to various mixtures of perfectly matched and GT-mismatched DNA double strands. The positions of the chip with the associated relative fluorescence intensities are indicated.
- Figure 16 shows the binding of Cy TM 5-labeled E.co//-mutS to various mixtures of perfectly paired and GT mismatched DNA double strands, which were generated by hybridization on an electronically addressable agarose chip. The mean red fluorescence intensity with standard deviation for the different double strands is shown in each case.
- 16A shows the binding of mutS to those with the first strand “sense” and the complementary ones Oligonucleotides AT (perfect pairing) and GT (mismatching) double strands obtained.
- 16B shows the binding of mutS to the double strands obtained with the oligonucleotide p53 se and the complementary counterstrands p53 AT (perfectly mating) and p53 GT (mismatching).
- the tumor suppressor gene p53 plays an important role in the development of cancer (B. Vogelstein, K.W. Kinzler, Cell 70 (1992), 523-526); Accordingly, mutations in p53 can serve as a prognostic marker for the development of a tumor. Over 90% of all known mutations in p53 are in the
- the numbering of the cell lines follows the identification by the DSMZ.
- MCF-7 (DSMZ ACC 1 15) is an adenocarcinoma cell line derived from mammary gland epithelium; no mutations in p53 are known (Landers JE et al. Translational enhancement of mdm2 oncogene expression in human tumor cells containing a stabilized wild-type p53 protein. Cancer Res. 57: 3562-3568, 1997)
- SW-480 (DSMZ ACC 313): established from a human colorectal adenocarcinoma, contains a G to A mutation in codon 273 of exon 8 of the p53 gene (Weiss J et al. Mutation and expression of the p53 gene in malignant melanoma cell lines. Int. J. Cancer 54: 693-699, 1993)
- MOLT-4 human T-lymphoblast cell line, contains a G to A mutation in codon 248 of exon 7 of p53 (Rodrigues NR et al. P53 mutations in colorectal cancer. Proc. Natl. Acad. Sei USA 87: 7555-7559, 1990)
- DSMZ ACC 305 is a human embryonic transformed with adenovirus
- Renal epithelial cell line for which no mutations in p53 exon 8 have been published.
- cell line SW-480 and possibly cell line 293 contains a mutation in exon 8 of the p53 gene.
- Exon 8 was amplified from the genomic DNA of the cell lines described by polymerase chain reaction (PCR).
- the respective PCR products (length: 237 bp) were then hybridized on a hydrogel chip with a synthetic oligonucleotide (length: 73 bases), the sequence of which corresponded to the wild-type sequence of the region to be examined.
- the chip was equipped with a single-strand-specific endonuclease (mung bean nuclease) and a Single strand binding protein treated. The binding of dye-labeled Eco / mutS to the different double strands was then investigated.
- the amplification was carried out in a thermal cycler (GeneAmp PCR System 2400, Perkin Elmer, Langen, Germany) under the following conditions: initial denaturation: 95 ° C, 2 min
- the PCR products were then purified using the QIAquick PCR Purification Kit from QIAGEN. This purification was carried out according to the manufacturer's instructions, but an additional washing step with 75% ethanol was carried out before the DNA was eluted. The DNA was finally eluted in 50 ul water.
- QIAquick PCR Purification Kit from QIAGEN. This purification was carried out according to the manufacturer's instructions, but an additional washing step with 75% ethanol was carried out before the DNA was eluted. The DNA was finally eluted in 50 ul water.
- the chip was removed from the charger, filled with equilibration buffer and the green fluorescence at the positions of the chip was measured in the Nanogen reader (device settings: medium gain, 256 ⁇ s integration time). The result of the measurement is shown in Table 2 ⁇ .
- the chip was then coated with 1 ⁇ l of Mung Bean Nuclease (NEB, Frankfurt) + ⁇ 9 ⁇ l
- Block buffer 20 mM Tris, pH 7.6 / 50 mM KCI / 5 mM MgCI 2 / 0.01% Tween-20/3%
- Incubation buffer 20 mM Tris, pH 7.6 / 50 mM KCI / 5 mM MgCI 2 / 0.01% Tween-20
- Wash buffer 20mM Tris, pH 7.6 / 50mM KCI / 5mM MgCl 2 / 0.1% Tween-20
- Table 27 Loading diagram of a hydrogel chip for the detection of mutations in the exon ⁇ of the p53 gene in human cell lines. The individual positions were first addressed with the oligonucleotide mentioned in the upper line and then with the PCR product of the various cell lines (MCF-7, MOLT-4, SW-4 ⁇ O and 293) mentioned in the second line or with the oligonucleotides AT or GT hybridized. As a control, some positions were only loaded with first or second strand; empty boxes do not symbolize positions loaded with DNA.
- Table 2 ⁇ Measurement of the green fluorescence intensity of the hydrogel chip before treatment with mung bean nuclease. The positions of the chip with the associated relative fluorescence intensities are indicated.
- Table 29 Measurement of the green fluorescence intensity of the hydrogel chip after treatment with mung bean nuclease. The positions of the chip with the associated relative fluorescence intensities are indicated.
- Table 30 Measurement of the red fluorescence intensity for the detection of the binding of Cy 5 -labeled E. coli mutS to double strands from a synthetic oligonucleotide and PCR products from different cell lines. The positions of the chip with the associated relative fluorescence intensities are indicated.
- Table 31 Statistical expansion of the results of the hydrogel chip for the detection of mutations in exon ⁇ of the p53 gene in different cell lines. The mean values and standard deviations of the red fluorescence intensities of all positions with the same load were calculated.
- FIG. 17 shows the binding of Cy TM 5-labeled Eco // mutS to double strands from a synthetic oligonucleotide and PCR products from different cell lines for the detection of mutations in exon 8 of the p53 gene. The mean red fluorescence intensity with standard deviation for the individual cell lines is shown in each case.
- Oligonucleotide cExon ⁇ had been hybridized with the PCR product of the cell line SW-480: the fluorescence intensities were about 6.5 times higher than at the positions where the hybridization with the PCR products of the cell lines MCF-7, MOLT-4 or 293. With the method described here, it has thus been possible to detect the known base exchange mutation of the cell line SW-480 in codon 273 of the p53 gene. Under the chosen experimental conditions, this base exchange led to a GT mismatch, which was clearly recognized by the dye-labeled mutS. In contrast, in the case of cell line 293, for which there is no information about possible mutations in p53, very similar fluorescence intensities were measured as for line MCF-7, which contains no mutations in the p53 gene. This indicates that the cell line 293 also contains no base exchange in the area examined.
- Protein is advantageous for the detection of mutations in genomic DNA, or whether these incubation steps can be omitted without loss of sensitivity.
- four hydrogel chips were loaded with first and second strands according to the same scheme and then treated according to different incubation protocols.
- the single-stranded, biotinylated PCR products are produced according to the following scheme: Genomic DNA from the MCF-7 cell line, which contains no mutation in the p53 gene, was used as the starting material for the PCR.
- the amplification was carried out in a thermal cycler (GeneAmp PCR System 2400, Perkin Elmer, Langen, Germany) under the following conditions: initial denaturation (95 ° C, 2 min), followed by 31 amplification cycles (each 95 ° C, 30 sec - 62 ° C) , 30 sec - 72 ° C, 1 min) and final elongation (72 ° C, 10 min)
- the PCR products were then purified using the QIAquick PCR Purification Kit from QIAGEN. This purification was carried out according to the manufacturer's instructions, but an additional washing step with 75% ethanol was carried out before the DNA was eluted.
- QIAquick PCR Purification Kit from QIAGEN. This purification was carried out according to the manufacturer's instructions, but an additional washing step with 75% ethanol was carried out before the DNA was eluted.
- DNA was finally eluted in 50 ul water.
- the biotinylated single strands were isolated using magnetic, streptavidin-coated beads from DYNAL Biotech (Hamburg).
- the PCR product was diluted with an equal volume of 2 ⁇ B&W buffer (10 mM Tris-HCl, pH 7.5, 1 mM EDTA, 2 M NaCI), mixed with Dynabeads M-280 streptavidin and at 15 min
- the “targets” were produced as described in the example “detection of mutations in genomic DNA” under “carrying out the polymerase chain reaction”.
- SsPCR was diluted with an equal volume of 100 mM histidine buffer.
- the biotinylated oligonucleotide cExon ⁇ (Seq. ID No. 47) and the oligonucleotides “APC se” (Seq. ID No. 24) used as positive and negative control, " APC AT “(Seq. ID No. 25) and” APC GT “(Seq. ID No. 26) were dissolved in a concentration of 100 nM in 50 mM histidine buffer. The cleaned as second strand
- PCR products were mixed with an equal volume of 100 mM histidine buffer. All DNA strands were then denatured for 5 min at 95 ° C. The different first strands were electronically addressed to defined positions of the hydrogel chips in the charger of the Nanogen workstation for 60 seconds at a voltage of 2.1 V. The hybridization with the Cy TM 3-labeled
- Chip A and B Two of the hydrogel chips (hereinafter referred to as chips A and B) were incubated with block buffer for 70 min at room temperature after loading. Chip B was then additionally incubated for 45 min with 22 ng / ⁇ l SSB (single-stranded DNA binding protein, USB Corporation, Cleveland, USA) in incubation buffer. Finally, both chips were incubated with 3 ⁇ l of Cy TM 5-labeled Eco // - MBP-mutS (concentration: 450 ng / ⁇ l) in 97 ⁇ l incubation buffer for 60 min at room temperature. The chips were then washed by hand with 1 ml of incubation buffer, inserted into the Nanogen reader and there 50x at a temperature of 37 ° C. with 0.25 ml each
- Chips C and D were filled with equilibration buffer after loading and the green fluorescence measured on the positions of the chips in the Nanogen reader
- the chips were then incubated for 45 min at 30 ° C. with 1 ⁇ l mung bean nuclease (NEB, Frankfurt) + 89 ⁇ l 1x mung bean nuclease buffer (NEB). After the nuclease digestion, the chips were washed with 20 ml equilibration buffer and then incubated with block buffer for 70 min at room temperature, after which chip D was additionally 45 min with 22 ng / ⁇ l SSB
- Tween-20 Block buffer 20mM Tris, pH 7.6 / 50mM KCI / 5mM MgCI 2 / 0.01% Tween-20/3% BSA
- Incubation buffer 20 mM Tris, pH 7.6 / 50 mM KCI / 5 mM MgCI 2 / 0.01% Tween-20/1%
- BSA Wash buffer 20 mM Tris, pH 7.6 / 50 mM KCI / 5 mM MgCI 2 / 0.1% Tween-20
- Chip A without nuclease, without SSB
- Chip B without nuclease, with SSB
- Tables 35 and 36 The results of the green fluorescence measurement from Chip C (with nuclease, without SSB) before
- Table 33 Measurement of green fluorescence from Chip A (without nuclease, without SSB). The positions of the chip with the associated relative fluorescence intensities after the incubation with mutS are indicated.
- Table 34 Measurement of the red fluorescence of Chip A (without nuclease, without SSB) for the detection of the binding of Cy TM 5-labeled i? .Co / -MBP-mutS. The positions of the chip with the associated relative fluorescence intensities are indicated.
- Table 36 Measurement of the red fluorescence from Chip B (without nuclease, with SSB) to detect the binding of Cy TM 5-labeled Ecoli-MEP-mutS. The positions of the chip with the associated relative fluorescence intensities are indicated.
- Table 37 Measurement of the relative green fluorescence intensities of Chip C before the nuclease digestion.
- Table 40 Measurement of the relative green fluorescence intensities of Chip D before the nuclease digestion.
- Table 42 Measurement of the red fluorescence from Chip D (with nuclease, with SSB) for the detection of the binding of Cy 1M 5-labeled J E'.co / z-MBP-mutS. The positions of the chip with the associated relative fluorescence intensities are indicated.
- Table 43 Statistical evaluation of the results of the hydrogel chips A-D. The mean values and standard deviations of the red fluorescence intensities of all positions with the same loading were calculated for each chip.
- Chip B treated with SSB has already achieved a significant reduction in red background fluorescence and improved mutation detection.
- Treatment with mung bean nuclease is very beneficial for the mutS-mediated detection of mutations in genomic DNA on electronically addressable microchips.
- Incubation with SSB also has a positive effect on mutation detection.
- Oligonucleotide as first strand (Fig. 18).
- Oligonucleotides already single-stranded, so that no separation of the complementary strand is necessary.
- the use of shorter oligonucleotides allows the position of a mutation that may be present to be more precisely restricted than when a longer PCR product is used as the first strand.
- one or the other of the two protocols described here can prove to be particularly suitable for mutS-mediated detection of mutations in genomic DNA.
- the first and second strand oligonucleotides were first dissolved in a concentration of 100 nM in histidine buffer and denatured for 5 min at 95 ° C.
- the electronic addressing of the biotinylated oligonucleotide "sense" (Seq. ID
- the chip was then incubated with 10 ⁇ l Cy TM 5-labeled Eco // mutS (concentration: 50 ng / ⁇ l) in 100 ⁇ l incubation buffer for 60 min at room temperature. After this incubation, the chip was washed manually with 10 ml wash buffer and then inserted into the Nanogen reader. There was washed 70x with 0.5 ml wash buffer at a temperature of 37 ° C.
- mutS chip system is therefore suitable for the rapid optical detection of mutations.
- Histidine buffer 50 mM L-histidine; this solution was filtered through a membrane with a pore size of 0.2 ⁇ m and degassed under reduced pressure
- Block buffer 20 mM Tris, pH 7.6 / 50 mM KCI / 5 mM MgCI 2 / 0.01% Tween-20/3% BSA (Serva, Heidelberg)
- Incubation buffer .20 mM Tris, pH 7.6 / 50 mM KCI / 5mM MgCl 2 / 0.01% Tween-20
- Table 44 Loading scheme of a chip for the optical detection of the binding of Cy 5-labeled E colimutS to mismatches: all positions were first addressed with oligonucleotide "sense" (Seq. TJ) No.10), then the positions shown were Oligonucleotides "AT” (Seq. ID No. 12) and "GT” (Seq. ID No. 13) are addressed.
- FIG. 20 shows the optical detection of mutations on electronically addressable DNA chips: FIG. 20A, the Cy TM 3 fluorescence shows an even loading of the chip with DNA, FIG. 20B, the Cy TM 5 fluorescence is in the positions with the Base mismatch (see Table 44) clearly visible and stands out well from the background.
- Thermus aquaticus mutS I. Biswas and P. Hsieh, J. Biol. Chem 271, 5040-5048 (1996), obtained commercially from Biozym (Hess.-Oldendorf, Germany)
- Thermus thermophilus HB8 mutS protein S. Takamatsu, R. Kato and S. Kuramitsu, Nucl. Acids Res. 24, 640-647 (1996), provided by Professor Kuramitsu, University of Osaka, Japan
- the proteins were then placed on a 1 ml DEAE-Sepharose fast flow column (Pharmacia, Sweden), which was equilibrated with 10 ml of 10 mM HEPES pH 7.9, 50 mM KCI, 5 mM MgCI 2 , 10% glycerol, 0.1 mM PMSF.
- Free dye active ester was removed by rinsing the column with 20 ml of 10 mM HEPES pH 7.9, 50 mM KCI, 5 mM MgCl 2 , 10% glycerol, 0.1 mM PMSF, and the protein was dissolved in 4 ml of 10 mM HEPES pH 7.9, 500 mM KCI , 5 mM MgCl 2 , 10% glycerol, 0.1 mM PMSF eluted. The intactness of the proteins after the purification was analyzed via SDS-PAGE.
- the proteins were dialysed twice for at least 3 hours against 21 10 mM HEPES pH 7.9, 50 mM KCI, 5 mM MgCl 2 , 10% glycerol, 0.1 mM PMSF and stored in 25 ⁇ l aliquots at -80 ° C.
- the protein concentrations of the different mutS proteins were first determined using the Bradford method. Depending on the protein concentration (0.1-1 mg / ml)
- the marking efficiencies are within an order of magnitude.
- Double strands containing one of the eight possible base mismatches (AA, AG, CA, CC, CT, GG, GT, TT),
- Double strands in which one strand contains an insertion of 1, 2 or 3 bases.
- the first and second strand oligonucleotides were first dissolved in a concentration of 100 nM in histidine buffer and denatured for 5 min at 95 ° C.
- the electronic addressing of the biotinylated oligonucleotide "sense" (Seq. ID No. 10) to the individual positions of the hydrogel chip was carried out in the charger of the Nanogen workstation for 60 seconds at a voltage of 2.1 V.
- the hybridization with the second strand oligonucleotides AT (Seq. ID No. 12), GT (Seq. ID No. 13), AA (Seq. ID No. 14), AG (Seq. ID No. 15), CA (Seq. ID No. 16), CC (Seq. ID No. 17),
- CT (Seq. ID No. 18), GG (Seq. ID No. 19), TT (Seq. ID NOr. 20), ins + 1T (Seq. ID No. 21), ins + 2T (Seq. ID No . 22) and ins + 3T (Seq. ID No. 23) was carried out at 2.1 V for 120 sec.
- the loading scheme is shown in Table 45; the name of each second-strand oligonucleotide indicates the mismatch or insertion ("ins") that occurs during hybridization.
- the chips were removed from the charger, filled with 1 ml of block buffer and incubated for 60 min at room temperature to saturate unspecific protein binding sites.
- the binding of E.co// ' mutS (ChipA), MBP-MutS (ChipB), Thermus aquaticus mutS (ChipC) and Thermus thermophilus mutS (ChipD) to the DNA double strands thus obtained was then tested.
- the chips were incubated with 2-3 ⁇ g of the Cy TM 5-labeled mutS proteins in 100 ⁇ l incubation buffer for 60 min.
- the chips with E.co//-mutS and MBP-MutS were incubated at room temperature, the chips with Thermus aquaticus mutS and Thermus thermophilus mutS at 37 ° C. After this incubation, the chips from
- thermophilic proteins surprisingly bind particularly well to insertion mutations. They are therefore suitable for a detection system of only insertion / de! Etion mutations and G / T base mismatches.
- both the E. coli mutS and the MBP MutS are suitable for the detection of a broad spectrum of base mismatches.
- the E. coli protein also provides the strongest absolute signals.
- the proteins from T. thermophilus and T. aquaticus preferentially bind to mismatches that result from insertions / deletions. This can be used to quickly detect this subtype of mutations.
- Histidine buffer 50 mM L-histidine; this solution was filtered through a membrane with a pore size of 0.2 ⁇ m and degassed under reduced pressure
- Block buffer 20 mM Tris, pH 7.6 / 50 mM KCI / 5 mM MgCI 2 / 0.01% Tween-20/3% BSA (Serva, Heidelberg)
- Incubation buffer 20 mM Tris, pH 7.6 / 50 mM KCI / 5 mM MgCI 2 / 0.01% Tween-20
- Wash buffer 20mM Tris, pH 7.6 / 50mM KCI / 5mM MgCl 2 / 0.1% Tween-20
- Table 45 Loading scheme of chips for the detection of the binding of Cy 5-labeled mutS to different base mismatches. "Neg.”: Positions not loaded with DNA. "SsDNA”: only with the Single strand “sense” loaded positions. All other positions were first addressed with the oligonucleotide "sense” and then hybridized with the second strand specified in the table.
- Table 46 Measurement of the red fluorescence from Chip A to detect the binding of Cy 5-labeled E. coli mutS to different base mismatches. The positions of the chip with the associated relative fluorescence intensities are indicated.
- Table 48 Measurement of the red fluorescence from Chip C to detect the binding of Cy 5-labeled Thermus aquaticus mutS to different base mismatches. The positions of the chip with the associated relative fluorescence intensities are indicated.
- Table 49 Measurement of the red fluorescence from Chip D to detect the binding of Cy 5-labeled Thermus thermophilus mutS to different base mismatches. The positions of the chip with the associated relative fluorescence intensities are indicated.
- mutS from E. coli, T. aquaticus, T. thermophilus and the MBP-mutS fusion protein were tested by means of biacore measurements.
- the analyzes were carried out on a Biacore2000 SPR biosensor (Biacore AB) at 22 ° C. in a running buffer made of 20mM HEPES (pH7.4), 50mM KCI, 5mM MgCI 2 and 0.005% Tween20 (protein grade, Calbiochem).
- the DNA oligonucleotides were immobilized on a streptavidin-coated surface of an SA sensor chip (Biacore AB) up to a surface density of 70 RU. An SA surface without DNA served as the control surface.
- the proteins were diluted in the running buffer in order to obtain a series of concentrations of 8 different concentrations of the respective protein, which were successively carried out over the
- the data evaluation was done with the help of the biaevaluation software version 3.1.
- the signals from the control surface were subtracted from the signals from the individual surfaces and the curves were normalized to the start of injection.
- the association and dissociation rate constants were determined either separately or via a global fit with a Langmuir 1: 1 binding model.
- the affinities were determined either separately or via a global fit with a Langmuir 1: 1 binding model.
- the binding of the GT mismatch for the four mutS variants (A: E. coli, B: T. thermophilus, C: T. aquatiqus, D: MBP-mutS) is shown by way of example in FIGS Association and dissociation constants are shown in FIG. 22.
- the high specificity of the mutS protein from T thermophilus for + 1T (FIG. 23B), for + 2T (FIG. 25B), for + 3T (FIG. 27B) compared to the MBP mutS (E. coli)
- FIGS. 23A, 25A, 27A Fusion protein (FIGS. 23A, 25A, 27A) is shown in FIGS. 23, 25, 27, the graphic representation of the determined constants gives FIG. 24 for the insertion + 1T, FIG. 26 for the insertion + 2T and FIG. 28 for the insertion + 3T again.
- Fig. 21 A 2.5 nM, 5 nM, 10 nM, 20 nM 39 nM, 79 nM, 158 nM
- Fig. 21B 3.5 nM, 7 nM, 14 nM, 27 nM, 55 nM, 110 nM, 219 nM, 438 nM
- Fig. 21C 3.4 nM, 7 nM 14 nM 28 nM 55 nM, 1 10 nM 221 nM, 441 nM Fig. 21 D: 2.8 nM, 5.7 nM, 1 1 nM, 23 nm, 45 nm, 91 nm 182 nm 363 nm
- 23A, 25A, 27A 5.7 nM, 1 1 nM, 23 nM, 45 nM 91 nM 182 nM, 363 nM, 726 nM Fig. 23B, 25B, 27B: 3.5 nM, 7 nM, 14 nM , 27 nM, 55 nM, 110 nM, 219 nM, 438 nM
- the Au electrodes (CH-Instruments, Austin, USA) were cleaned by polishing the electrode surface with a 0.3 ⁇ m alumina suspension (LECO, St. Joseph, USA) and subsequent rinsing with Millipore water (10 M ⁇ cm) , The subsequent electrochemical cleaning of the electrodes was carried out in 0.2 M NaOH using cyclic voltammetry (potentiostat: EG&G PAR 273A, GB), the electrodes first 5 times between potentials of -0.5 and -1.8 V (against Ag / AgCI- Reference electrode (Metrohm GmbH & Co, Filderstadt, D) 3 M NaCI) and then cycled 3 times between -0.3 and 1.1 V (feed rate 50 mV sec " 1 ). A platinum rod serves as the counter electrode for cyclic voltammetry (Metrohm).
- the 5 ' -SH-modified oligonucleotide hairpins (Interactiva, Ulm, D) (Seq. ID No. 50 and Seq. ID No. 51) are connected by incubating the cleaned Au electrodes with a 100 ⁇ M solution of the corresponding thiol -modified oligonucleotides in 0.9 M phosphate buffer (pH 6.6, Calbiochem; addition of 0.5 mM
- Dithiothreitol (DTT, Sigma-Aldrich, Steinheim, D)) for 6.5 h.
- the resulting oligonucleotide monolayers were characterized by blocking the diffusion-controlled Fe (II / III) redox reaction in aqueous K3 / K4Fe (CN) 6 solution (salts from Merck, Darmstadt, D) (20 mM in 20 mM phosphate buffer pH 7) checked using cyclic voltammetry (CV).
- the gaps between the individual oligonucleotide molecules on the monolayer were filled by incubating the electrodes in a 1 mM solution of 6-mercaptohexanol (Aldrich, USA) in Millipore water (degassed) for 60-90 minutes
- the electrodes were stored in 1 M phosphate buffer at 4 ° C. until the actual measurement.
- the individual electrodes were in aqueous K3 / K4Fe (CN) 6 solution (Darmstadt, D) (20 mM in 20 mM Tris buffer, 100 mM KCI, 5 mM MgCI) in the frequency range from 100 MHz to 1 MHz to 100 MHz and before measure after incubation with MutS.
- the Measured values are shown in the Bode diagram. The measurements were carried out on an IM 6e impedance measuring station from Zahner Messtechnik at room temperature.
- Nucleic acid sequence: 5 ' -3 ' X amino modifier dT MutS substrate Seq. ID No. 50 ATT CGA TCG GGG CGG GGC GAG CTT TTX GCT CGC CTT
- GCC CCG ATC GAA T Seq. ID No. 51 ATT CGA TCG GGG CGG GGC GAG CTT XTT GCT CGC CCC
- Impedance spectroscopy was used for the electrochemical investigation. With this examination method, an AC voltage is applied to the system to be examined, the frequency of which varies and the AC resistance is measured in the process. In particular, computer-aided
- FIG. 29A shows two measurements of the sequence Seq ID No. containing two GT mismatches. 50
- Fig. 29B shows two measurements using Seq ID
- This example is intended to show that the detection of mutations with fluorescent dye-labeled mutS from E. coli as a mispairing substrate works in a wide range of DNA concentrations.
- the individual positions of a hydrogel chip were loaded with differently concentrated solutions of perfectly mating or GT mismatching first and second strand oligonucleotides and the binding of mutS to the respective positions was then determined.
- the oligonucleotides used were each dissolved in several different concentrations (100 nM, 33 nM, 10 nM, 3.3 nM, 1 nM and 0.33 nM) in histidine buffer and denatured for 5 min at 95 ° C.
- Oligonucleotides "sense" (Seq. ID No. 10) on the individual positions of a hydrogel chip were carried out in the charger of the Nanogen workstation for 60 seconds at a voltage of 2.1 V.
- the loading scheme is shown in Table 52.
- the chip was removed from the charger, filled with 1 ml of block buffer and incubated for 60 min at room temperature to saturate unspecific protein binding sites.
- the chip was then incubated with 10 ⁇ l of Cy5-labeled E. co // mutS (concentration: 50 ng / ⁇ l) in 90 ⁇ l incubation buffer for 60 min at room temperature.
- the chip was washed by hand with 1 ml of incubation buffer, then inserted into the Nanogen reader and washed 50 times with 250 ⁇ l of washing buffer at a temperature of 37 ° C.
- the Cy TM 5 fluorescence intensity was measured on the individual positions of the chip in the Nanogen reader with the following device setting: high sensitivity ("high gain”); 256 ⁇ s integration time.
- Histidine buffer 50 mM L-histidine, filtered through a 0.2 ⁇ m membrane and degassed
- Block buffer 20 mM Tris, pH 7.6 / 50 mM KCI / 5 mM MgCI 2 / 0.01% Tween-20/3%
- Incubation buffer 20 mM Tris, pH 7.6 / 50 mM KCI / 5 mM MgCI 2 / 0.01% Tween-20
- Wash buffer 20mM Tris, pH 7.6 / 50mM KCI / 5mM MgCl 2 / 0.1% Tween-20
- Table 52 Loading diagram of a hydrogel chip with differently concentrated first and second strands. The individual positions were first loaded with the respective concentration of the biotinylated oligonucleotide "sense” and then hybridized with the second strand oligonucleotides "AT” or “GT” in the concentrations listed. As a control, some positions were only loaded with first or second strand ; Position 6/2 remained free as a reference electrode.
- Table 53 Measurement of the red fluorescence intensity of the hydrogel chip loaded with differently concentrated OMgonucleotides for the detection of the binding of Cy5-labeled E. coli-matS. The positions of the chip with the associated relative fluorescence intensities are indicated.
- Table 54 Statistical evaluation of the mutS binding on the hydrogel chip loaded with differently concentrated oligonucleotides. The mean values and standard deviations of the red fluorescence intensity of all positions with the same load were calculated.
- the concentration of the "sense" oligonucleotide used as the first strand was 100 nM in each case; the oligonucleotides AT and GT used as the second strand were used in the concentrations indicated in the diagram.
- the mean red fluorescence intensity after mutS binding is shown for the individual second strand concentrations ,
- Figure 31 shows the first strand dilution series.
- the “sense” oligonucleotide used as the first strand was used in the concentrations indicated in the diagram.
- the concentration of the oligonucleotides AT and GT used as the second strand was 100 nM in each case.
- the mean red fluorescence intensity after mutS binding is shown for the individual first strand concentrations
- 32 shows the simultaneous dilution of first and second strand.
- the "sense" oligonucleotide used as the first strand and the oligonucleotides AT and GT used as the second strand were diluted equally; the concentrations used are indicated in the diagram.
- the middle red is shown for the individual oligonucleotide concentrations
- the GT mismatch of mutS is more strongly bound by a factor of 7.5 than the perfect pairing (AT), and even when using 10 nM second-strand solutions, the GT mismatch is still a factor of 1, 7 recognized compared to the perfect pairing.
- the concentration of the first-strand solution used is lowered at a constant second-strand concentration of 100 nM, the GT mismatch is bound even more strongly by mutS than the perfect pairing at a first-strand concentration of only 1 nM (Fig. 31).
Abstract
Description
Claims
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AU2001270635A AU2001270635A1 (en) | 2000-08-04 | 2001-07-13 | Method for detecting mutations in nucleotide sequences |
EP01949494A EP1307589A2 (de) | 2000-08-04 | 2001-07-13 | Verfahren zum nachweis von mutationen in nucleotidsequenzen |
IL15427001A IL154270A0 (en) | 2000-08-04 | 2001-07-13 | Method for detecting mutations in nucleotide sequences |
CA002417861A CA2417861A1 (en) | 2000-08-04 | 2001-07-13 | Method for detecting mutations in nucleotide sequences |
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WO2005001122A2 (en) * | 2003-06-27 | 2005-01-06 | Adnavance Technologies, Inc. | Electrochemical detection of dna binding |
JPWO2004061100A1 (ja) * | 2002-12-10 | 2006-05-11 | オリンパス株式会社 | 核酸の変異解析方法および遺伝子の発現解析方法 |
WO2008065415A2 (en) * | 2006-12-01 | 2008-06-05 | Bioline Limited | Protein precipitation using a tag |
EP2952524A1 (de) | 2007-10-17 | 2015-12-09 | Janssen Sciences Ireland UC | Vom apoe-status abhängige immuntherapiedosierungen |
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AU2003210259A1 (en) * | 2002-02-21 | 2003-09-09 | Nanogen Recognomics Gmbh | Method for detecting single nucleotide polymorphisms |
US8168120B1 (en) | 2007-03-06 | 2012-05-01 | The Research Foundation Of State University Of New York | Reliable switch that is triggered by the detection of a specific gas or substance |
GB0718957D0 (en) * | 2007-09-28 | 2007-11-07 | Ge Healthcare Ltd | Optical imaging agents |
GB0718967D0 (en) * | 2007-09-28 | 2007-11-07 | Ge Healthcare Ltd | Peptide imaging agents |
JP5300335B2 (ja) * | 2008-06-06 | 2013-09-25 | 株式会社日清製粉グループ本社 | ミスマッチ塩基対含有核酸断片の高効率調製方法 |
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JP2010193897A (ja) * | 2002-12-10 | 2010-09-09 | Olympus Corp | 対象中の遺伝子の解析方法 |
WO2005001122A2 (en) * | 2003-06-27 | 2005-01-06 | Adnavance Technologies, Inc. | Electrochemical detection of dna binding |
WO2005001122A3 (en) * | 2003-06-27 | 2005-11-24 | Adnavance Technologies Inc | Electrochemical detection of dna binding |
WO2008065415A2 (en) * | 2006-12-01 | 2008-06-05 | Bioline Limited | Protein precipitation using a tag |
WO2008065415A3 (en) * | 2006-12-01 | 2008-07-31 | Bioline Res Ltd | Protein precipitation using a tag |
EP2952524A1 (de) | 2007-10-17 | 2015-12-09 | Janssen Sciences Ireland UC | Vom apoe-status abhängige immuntherapiedosierungen |
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US20040110161A1 (en) | 2004-06-10 |
WO2002012553A3 (de) | 2003-01-30 |
AU2001270635A1 (en) | 2002-02-18 |
JP2004520010A (ja) | 2004-07-08 |
EP1307589A2 (de) | 2003-05-07 |
DE10038237A1 (de) | 2002-02-14 |
IL154270A0 (en) | 2003-09-17 |
CA2417861A1 (en) | 2003-02-03 |
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