WO2001061047A1 - Methods for identifying signalling molecules - Google Patents
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- WO2001061047A1 WO2001061047A1 PCT/US2001/005191 US0105191W WO0161047A1 WO 2001061047 A1 WO2001061047 A1 WO 2001061047A1 US 0105191 W US0105191 W US 0105191W WO 0161047 A1 WO0161047 A1 WO 0161047A1
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07K—PEPTIDES
- C07K14/00—Peptides having more than 20 amino acids; Gastrins; Somatostatins; Melanotropins; Derivatives thereof
- C07K14/415—Peptides having more than 20 amino acids; Gastrins; Somatostatins; Melanotropins; Derivatives thereof from plants
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- the present invention relates to signalling molecules that mediate biological responses, and to biological receptors. Background of the Invention
- signalling molecules include peptides, oligosaccharides, and fatty acid derivatives, such as jasmonic acid. Isolation of a signalling molecule that mediates a biological response provides the opportunity, for example, to utilize genetic engineering techniques to manipulate the biological response to produce plants having desirable properties, such as an enhanced resistance to pest or pathogen attack.
- Signalling molecules are typically present at very low concentrations within plants, or within organisms (such as pathogenic fungi) that induce a biological response in plants. Consequently, the purification of a sufficiently large amount of a signalling molecule for chemical analysis is a daunting technical problem. Thus there is a need for methods that facilitate the identification and isolation of signalling molecules that elicit a biological response in plants.
- the present invention provides methods for identifying and isolating signalling molecules, such as signalling molecules that interact with a plant cell membrane receptor molecule.
- signalling molecules such as signalling molecules that interact with a plant cell membrane receptor molecule.
- the ability of a sample of biological material to induce a pH change in a liquid plant cell culture is used as an assay for the presence of one or more signalling molecules in the biological mate ⁇ al
- a liquid plant cell culture is a culture in which plant cells are grown in a liquid medium
- the present invention provides methods for isolating signalling molecules including the steps of incubating a liquid plant cell culture, including plant cells and supernatant, m the presence of an aliquot of a biological mate ⁇ al, measu ⁇ ng a change of pH m the plant cell culture, the pH change being induced by the biological mate ⁇ al, and at least partially pu ⁇ fying a signalling molecule (that is capable of inducing a pH change in a liquid plant cell culture) from the biological mate ⁇ al Typically, the pH change is measured in the supernatant of the liquid plant cell culture
- the term "at least partially pu ⁇ fying”, and grammatical equivalents thereof, as used herein, means that the proportion of the signalling molecule(s) in the biological mate ⁇ al is higher after pu ⁇ fication than before pu ⁇ fication
- the signalling molecule(s) will be pu ⁇ fied to at least 90% pu ⁇ ty, more preferably to at least 95% pu ⁇ ty, most preferably to at least
- the present invention provides methods for isolating signalling molecules, the methods including a plurality of pu ⁇ fication steps, each of the plurality of pu ⁇ fication steps including the steps of incubating a liquid plant cell culture, including plant cells and supernatant, in the presence of an aliquot of a biological mate ⁇ al; measu ⁇ ng a change of pH in the incubated cell culture, the pH change being induced by the biological mate ⁇ al; and at least partially pu ⁇ fying a signalling molecule (that is capable of inducing a pH change in a liquid plant cell culture) from the biological mate ⁇ al.
- the pH change is measured in the supernatant of the liquid plant cell culture.
- the present invention provides methods for isolating signalling molecules, the methods including the steps of separating a biological mate ⁇ al into at least two fractions having different chemical compositions; contacting a liquid plant cell culture, including plant cells and supernatant, with a portion of at least one of the fractions; measu ⁇ ng a change of pH in the contacted plant cell culture, the pH change being induced by the biological mate ⁇ al, and at least partially pu ⁇ fying a chemical signalling molecule (that is capable of inducing a pH change in a liquid plant cell culture) from the biological mate ⁇ al Typically, the pH change is measured in the supernatant of the liquid plant cell culture.
- the present invention provides methods for isolating signalling molecules including the steps of contacting a plurality of liquid plant cell cultures, each culture including plant cells and supernatant, with a plurality of biological materials; measuring a change of pH in the contacted plant cell culture, the pH change being induced by the biological material, and at least partially purifying a signalling molecule (that is capable of inducing a pH change in a liquid plant cell culture) from the biological material.
- the pH change is measured in the supernatant of the liquid plant cell culture.
- the present invention provides signalling molecules prepared in accordance with the methods of the present invention, such as the polypeptide signalling molecules isolated as described in Example 1 and Example 2 herein.
- the present invention provides isolated polypeptides consisting of the amino acid sequence set forth in SEQ ID NO: 1 or SEQ ID NO: 2.
- FIGURE 1 is a schematic representation of one embodiment of the methods of the present invention.
- FIGURE 2A shows the elution profile of fractionated tobacco plant material eluted, as described in Example 1, from a semi-preparative, reversed-phase, C18 column and assayed for ability to induce alkalinization of tobacco liquid cell culture.
- FIGURE 2B shows the alkalinization profile of fractionated tobacco plant material eluted, as described in Example 1, from a semi-preparative, reversed-phase, C18 column and assayed for ability to induce alkalinization of tobacco liquid cell culture.
- Peaks I and II contained tobacco systemins I (SEQ ID NO: 1) and II, (SEQ ID NO: 1)
- FIGURE 3 A shows the elution profile of tobacco systemin I (SEQ ID NO: 1) from a narrow bore reversed-phase C18 column, as described in Example 1 herein.
- the peak identified as Peak lb is tobacco systemin I (SEQ ID NO: 1)
- peak la is an analogue of tobacco systemin I in which Ala at position 3 is substituted with threonine at position 3.
- FIGURE 3B shows the alkalinization profile (assayed in tobacco cell culture) of fractions containing tobacco systemin I (SEQ ID NO: 1) eluted from the narrow bore reversed-phase C18 column, as described in Example 1.
- FIGURE 4A shows the elution profile of tobacco systemin II (SEQ ID NO: 2) from a narrow bore reversed-phase C18 column, as described in Example 1 herein. The peak identified as Peak 1 contained most tobacco systemin II (SEQ ID NO: 2).
- FIGURE 4B shows the alkalinization profile (assayed in tobacco cell culture) of fractions containing tobacco systemin II (SEQ ED NO: 2) eluted from the narrow bore reversed-phase C18 column, as described in Example 1.
- FIGURE 5A shows the elution profile from a semi-preparative, reversed phase, C18 FJPLC column of fractionated tobacco plant material containing the 5 kDa polypeptide disclosed in Example 2 herein.
- the arrows indicate the eluted fractions that contained most of the 5 kDa polypeptide.
- FIGURE 5B shows the alkalinization profile of fractionated tobacco plant material containing the 5 kDa polypeptide disclosed in Example 2 herein.
- the arrow indicates the eluted fraction that contained most of the 5 kDa polypeptide.
- FIGURE 6 shows a comparison of the ability of tobacco systemin I (TOB-I) (SEQ ID NO: 1), tobacco systemin II (TOB-II) (SEQ ED NO: 2), tomato systemin (TOM SYS) and the 5 kDa polypeptide (identified as AF in FIGURE 6) disclosed in Example 2, to induce a pH increase in liquid plant cell cultures.
- TOB-I tobacco systemin I
- TOB-II tobacco systemin II
- TOM SYS tomato systemin
- 5 kDa polypeptide identified as AF in FIGURE 6
- FIGURE 7A shows the alkalinization profile (using N. tabacum suspension cultured cells) of extracts from flower buds of mature tobacco plants.
- FIGURE 7B shows the alkalinization profile (using N. tabacum suspension cultured cells) of extracts from leaves of young tobacco plants Detailed Description of the Prefe ⁇ ed Embodiment
- the present invention provides methods for isolating signalling molecules.
- Signalling molecules are molecules that elicit a response from a biological cell, such as a plant cell.
- Representative examples of biological responses elicited by signalling molecules are growth, development, response to cellular damage, response to environmental stimuli and response to pest or pathogen attack.
- Examples of plant responses to pest or pathogen attack include the production of proteinase inhibitor proteins and other defensive proteins such as phytoalexins. Additionally, plant defense responses are reviewed, for example, by E. Kombrink and I.E. Somssich, "Defense Responses of Plants to Pathogens" in Advances in Biochemical Research 21:1-34 (1995), Academic Press.
- Signalling molecules isolatable by the methods of the present invention can be of microbial origin, such as those that microorganisms release in their various interactions with plants, such as pathogens, nitrogen fixers, saprophytes and micorhizzae.
- Signalling molecules can be a chemical compound or chemical element.
- signalling molecules can be proteins, peptides, such as systemin, carbohydrates, such as plant cell wall fragments, volatile compounds, such as ethylene or methyl jasmonate, cyclic organic compounds such as auxins, cytokinins, gibberellins, abscisic acid, or chemical elements, such as metal ions.
- Some signalling molecules interact with a receptor molecule which may be located in, or associated with, a cellular membrane, such as the plasma membrane that encloses the cell. Other signalling molecules interact with soluble receptors within the cell, or interact directly with genomic DNA.
- cellular material such as plant material (for example; leaves, stems, roots, flowers, seeds and storage organs) or microorganisms (such as pathogenic bacteria and fungi that cause plant disease, or symbiotic bacteria such as Rhizobium) is treated so as to yield a biological material that is to be tested for the presence of one or more signalling molecules.
- the cellular material may be treated to disrupt cells, for example by homogenizing the cellular material in a blender, or by grinding (in the presence of acid-washed, siliconized, sand if desired) the cellular material with a mortar and pestle, or by subjecting the cellular material to osmotic stress that lyses the cells.
- Cell disruption may be carried out in the presence of a buffer that maintains the contents of the disrupted cells at a desired pH, such as the physiological pH of the cells.
- the buffer may optionally contain inhibitors of endogenous, degradative enzymes, such as proteases and amylases.
- the cellular material may also be treated in a manner that does not disrupt a significant proportion of cells, but which removes chemicals from the surface of the cellular material, and/or from the interstices between cells (or from the interstices within plant cell walls).
- the cellular material can be soaked in a liquid buffer, or, in the case of plant material, can be subjected to a vacuum, in order to remove chemicals located in the intercellular spaces and/or in the plant cell wall. If the cellular material is a microorganism, the supernatant of the microorganism culture can be tested for its ability to cause a change in the pH of a liquid plant cell culture.
- the homogenization buffer may include reductant, polyphenol inactivators, and protease inhibitors.
- a buffer hereinafter termed a homogenization buffer
- the homogenization buffer may include reductant, polyphenol inactivators, and protease inhibitors.
- Labile compounds are preferably added to the buffer immediately before cellular disruption. Covalent inhibitors need only be present during disruption of the cellular material, while competitive inhibitors should be present at all stages of the purification of the signalling molecule(s).
- reductants examples include dithiothreitol (DTT), for example at a working concentration of 2 to 5 mM, or 2-mercaptoethanol, for example at a working concentration of 14 mM.
- DTT dithiothreitol
- 2-mercaptoethanol for example at a working concentration of 14 mM.
- reductants include ascorbate and reduced glutathione.
- protease inhibitors include: serine protease inhibitors (such as phenylmethylsulfonyl fluoride (PMSF), benzamide, benzamidine HC1, ⁇ -Amino-n-caproic acid and aprotinin (Trasylol)); cysteine protease inhibitors, such as sodium p-hydroxymercuribenzoate; competitive protease inhibitors, such as antipain and leupeptin; covalent protease inhibitors, such as iodoacetate and N-ethylmaleimide; aspartate (acidic) protease inhibitors, such as pepstatin and diazoacetylnorleucine methyl ester (DAN); metalloprotease inhibitors, such as EGTA [ethylene glycol bis( ⁇ -aminoethyl fluoride (PMSF), benzamide, benzamidine HC1, ⁇ -Amino-n-caproic acid and aprotinin (
- composition of homogenization buffer can readily be modified, without undue experimentation, to identify an extraction regime that permits extraction of one or more signalling molecules in biologically active form.
- Representative homogenization buffers and extraction regimes are set forth in Example 1 herein.
- the biological material can be tested, without further purification or treatment, for its ability to induce a pH change in a liquid plant cell culture, provided it is not buffered to prevent an induced pH change from occurring, or the biological material can be further treated to generate fractions having different chemical compositions.
- the biological material can be fractionated by any art-recognized means.
- biological material in liquid form such as plant parts ground up in a homogenization buffer
- the precipitated material can be separated from the unprecipitated material by centrifugation, or by filtration.
- the precipitated material (whether or not resolubilized) and the unprecipitated material can then be tested for its ability to induce a pH change in a plant cell culture, or can be further fractionated if so desired.
- a number of different neutral or slightly acidic salts have been used to solubilize, precipitate, or fractionate proteins in a differential manner. These include NaCl, Na 2 S0 4 , MgSO 4 and NEE 4 (S0 ) .
- Ammonium sulfate is the precipitant used most frequently in the salting out of proteins.
- the biological material to be treated with ammonium sulfate should first be clarified by centrifugation.
- the biological material should be in a buffer at neutral pH unless there is a reason to conduct the precipitation at another pH; in most cases the buffer will have ionic strength close to physiological. Precipitation is usually performed at 0-4°C and all solutions should be precooled to that temperature range.
- the weight of solid ammonium sulfate needed to bring the volume of starting material to 80-85% saturation should be determined and the required amount of ammonium sulfate weighed out.
- the vessel containing the biological material should be equipped with a thermometer and a glass electrode for monitoring pH, and a suitable magnetic or motor-driven stirrer. Ammonium sulfate is added in increments with constant stirring and with adjustment of pH by addition of 1 N NHUOH, as required. Each addition of salt is made only after the previously added amount has completely dissolved. When all of the salt has been added, the mixture is stirred for another 15 to 30 min to allow equilibration of the solvent and protein.
- the mixture is then centrifuged at about 10,000 g for 10 min, or 3000 g for 30 min, in a precooled centrifuge at 0-4°C.
- the supernatant fluid can be decanted or drawn off by suction.
- Representative examples of other art-recognized techniques for purifying, or partially purifying, signalling molecules (including peptides and/or proteins) from biological material are exclusion chromatography, ion-exchange chromatography, hydrophobic interaction chromatography, reversed-phase chromatography and immobilized metal affinity chromatography.
- Hydrophobic interaction chromatography and reversed-phase chromatography are two separation methods based on the interactions between the hydrophobic moieties of a sample and an insoluble, immobilized hydrophobic group present on the chromatography matrix.
- hydrophobic interaction chromatography the matrix is hydrophilic and is substituted with short-chain phenyl or octyl nonpolar groups.
- the mobile phase is usually an aqueous salt solution.
- reversed phase chromatography the matrix is silica that has been substituted with longer n-alkyl chains, usually C 8 (octylsilyl) or C 18 (octadecylsilyl).
- the matrix is less polar than the mobile phase.
- the mobile phase is usually a mixture of water and a less polar organic modifier.
- hydrophobic interaction chromatography matrices are usually done in aqueous salt solutions, which generally are nondenaturing conditions. Samples are loaded onto the matrix in a high-salt buffer and elution is by a descending salt gradient. Separations on reversed-phase media are usually done in mixtures of aqueous and organic solvents, which are often denaturing conditions.
- hydrophobic interaction chromatography depends on surface hydrophobic groups and is carried out under conditions which maintain the integrity of the protein molecule.
- Reversed-phase chromatography depends on the native hydrophobicity of the protein and is carried out under conditions which expose nearly all hydrophobic groups to the matrix, i.e., denaturing conditions.
- Ion-exchange chromatography is designed specifically for the separation of ionic or ionizable compounds.
- the stationary phase (column matrix material) carries ionizable functional groups, fixed by chemical bonding to the stationary phase. These fixed charges carry a counterion of opposite sign. This counterion is not fixed and can be displaced.
- Ion-exchange chromatography is named on the basis of the sign of the displaceable charges. Thus, in anion ion-exchange chromatography the fixed charges are positive and in cation ion-exchange chromatography the fixed charges are negative.
- Retention of a molecule on an ion-exchange chromatography column involves an electrostatic interaction between the fixed charges and those of the molecule, binding involves replacement of the nonfixed ions by the molecule. Elution, in turn, involves displacement of the molecule from the fixed charges by a new counterion with a greater affinity for the fixed charges than the molecule, and which then becomes the new, nonfixed ion.
- the ability of counterions (salts) to displace molecules bound to fixed charges is a function of the difference in affinities between the fixed charges and the nonfixed charges of both the molecule and the salt. Affinities in turn are affected by several variables, including the magnitude of the net charge of the molecule and the concentration and type of salt used for displacement.
- Solid-phase packings used in ion-exchange chromatography include cellulose, dextrans, agarose, and polystyrene.
- the exchange groups used include DEAE (diethylaminoethyl), a weak base, that will have a net positive charge when ionized and will therefore bind and exchange anions; and CM (carboxymethyl), a weak acid, with a negative charge when ionized that will bind and exchange cations.
- Another form of weak anion exchanger contains the PEI (polyethyleneimine) functional group. This material, most usually found on thin layer sheets, is useful for binding proteins at pH values above their pi.
- the polystyrene matrix can be obtained with quaternary ammonium functional groups for strong base anion exchange or with sulfonic acid functional groups for strong acid cation exchange. Intermediate and weak ion-exchange materials are also available. Ion-exchange chromatography need not be performed using a column, and can be performed as batch ion-exchange chromatography with the slurry of the stationary phase in a vessel such as a beaker.
- polysulfoethyl aspartamide has been used as a cation exchanger (at pH 3) in HPLC as part of a purification protocol for plant polypeptide signalling molecules.
- Gel filtration is performed using porous beads as the chromatographic support.
- a column constructed from such beads will have two measurable liquid volumes, the external volume, consisting of the liquid between the beads, and the internal volume, consisting of the liquid within the pores of the beads. Large molecules will equilibrate only with the external volume while small molecules will equilibrate with both the external and internal volumes.
- a mixture of molecules (such as peptides) is applied in a discrete volume or zone at the top of a gel filtration column and allowed to percolate through the column. The large molecules are excluded from the internal volume and therefore emerge first from the column while the smaller molecules, which can access the internal volume, emerge later.
- the volume of a conventional matrix used for protein purification is typically 30 to 100 times the volume of the sample to be fractionated.
- HPLC High Performance Liquid Chromatography
- HPLC is an advancement in both the operational theory and fabrication of traditional chromatographic systems. HPLC systems for the separation of biological macromolecules vary from the traditional column chromatographic systems in three ways; (l) the column packing materials are of much greater mechanical strength, (2) the particle size of the column packing materials has been decreased 5- to 10-fold to enhance adsorption-desorption kinetics and diminish bandspreading, and (3) the columns are operated at 10-60 times higher mobile-phase velocity.
- HPLC can utilize exclusion chromatography, ion-exchange chromatography, hydrophobic interaction chromatography, reversed-phase chromatography and immobilized metal affinity chromatography.
- An exemplary purification strategy that has been found useful in the practice of the present invention for purifying plant signalling molecules is reverse phase, low pressure batch C ]8 chromatography, followed by G-25 sephadex gel filtration, then further purification using HPLC.
- the pH is preferably kept low by the addition of 0.1% trifluoroacetic acid which can be removed by lyophilization. This approach was used to purify the plant signalling molecules described in Examples 1 and 2 herein.
- a biological material Once a biological material has been prepared, a liquid plant cell culture is contacted with an aliquot of the biological material in order to test the ability of the biological material to induce a pH change in the plant cell culture.
- the cell culture can be derived from any species of plant, including gymnosperm or angiosperm plant species.
- Representative plant species include: tomato plants (including Lycopersicon esculentum and Lycopersicon peruvianmn), potato plants, tobacco plants, alfalfa plants, maize plants and plants of the genus Arabidopsis.
- Art- recognized techniques for preparing and maintaining plant cell cultures are set forth in "Plant Cell Culture, A Practical Approach” (R.A. Dixon, ed.), Oxford University Press, 2 nd edition (1995), which publication is incorporated herein by reference.
- Representative plant cell culture techniques useful in the practice of the present invention are set forth in Example 4 herein.
- a liquid plant cell culture is incubated in the presence of an aliquot of biological material for a period of time that is sufficient for a signalling molecule- induced change in the pH of the cell culture to occur.
- the required period of time can be readily determined by one of ordinary skill in the art, without undue experimentation, for example by conducting a time course experiment by adding equal aliquots of biological material to equal aliquots of a liquid plant cell culture, and measuring the pH of a cell culture aliquot at defined time intervals after addition of the biological material.
- a liquid plant cell culture is incubated in the presence of an aliquot of biological material for from about one minute to about thirty minutes, more preferably from about five minutes to about ten minutes.
- Some signalling molecules only induce a pH change in a liquid plant cell culture prepared from the same plant species from which the signalling molecule was isolated.
- Other signalling molecules induce a pH change in liquid plant cell cultures prepared from one or more plant species in addition to the plant species from which the signalling molecule was isolated.
- a liquid plant cell culture is utilized that is prepared from the same plant species from which the signalling molecule is isolated.
- the pH of the plant cell culture can increase or decrease in response to the presence of a signalling molecule in the biological material.
- the pH of the cell culture may transiently decrease (or increase) before increasing (or decreasing).
- the change can be measured by any art-recognized means for measuring pH, such as a pH meter that measures the conductivity of a solution as an indicator of pH, or a colorimetric assay, such as chemically-treated substrate (such as litmus paper), in which the pH of the material being assayed is indicated by the color of the substrate.
- any change in pH may be indicative of the presence of a signalling molecule in the biological material being tested, typically a change of at least 0.3 pH units, more preferably at least 0.8 pH units, most preferably at least 1.0 pH units, is considered indicative of the presence of a signalling molecule in the biological material.
- the change in pH of a liquid plant cell culture incubated in the presence of a biological material including a signalling molecule may be caused by interaction of the signalling molecule with a plasma membrane-bound receptor molecule that causes ion transport across the plasma membrane of the plant cell.
- a biological material including a signalling molecule may be caused by interaction of the signalling molecule with a plasma membrane-bound receptor molecule that causes ion transport across the plasma membrane of the plant cell.
- H + ions hydrogen ions
- K + ions potassium ions
- FIGURE 1 shows a schematic representation of one embodiment of the present invention that utilizes several rounds of assay and purification of a plant extract to purify a signalling molecule from the extract.
- Any art-recognized technique (or combination thereof) can be used to further purify one or more signalling molecules from biological material. Examples of art-recognized protein purification techniques are set forth supra.
- the present invention provides methods for isolating signalling molecules including the steps of contacting a plurality of liquid plant cell cultures, each culture including plant cells and supernatant, with a plurality of biological materials; measuring a change of pH in the contacted plant cell culture, and at least partially purifying a chemical signalling molecule (that is capable of inducing a pH change in a liquid plant cell culture) from the biological material.
- the plurality of cell cultures can be contained within a plurality of separate containers, such as glass laboratory flasks or beakers, or within a container (or plurality of such containers) that defines a plurality of separate reservoirs, such as the wells of a microtitre plate.
- a container or plurality of such containers that defines a plurality of separate reservoirs, such as the wells of a microtitre plate.
- 1 ml of a liquid plant cell culture is placed into each well of a 24 well tissue culture plate, and from about 1 ⁇ l to about 20 ⁇ l of biological material to be assayed is added to each aliquot of liquid plant cell culture.
- the methods of the present invention may be automated, for example by providing an automated dispensing means, which dispenses measured amounts of a biological material into a plurality of aliquots of a liquid plant cell culture, an automated incubation means which incubates the plant cell culture aliquots in the presence of the biological material under defined incubation conditions for a desired period of time, and an automated measuring means which measures the pH of the plant cell culture aliquots before and after (and optionally during) incubation of the cell culture aliquots in the presence of the biological material.
- the yield from each preparation averaged 0.91 g dry powder.
- the dry powder was dissolved in 5 ml 0.1% TFA and passed through a G-25 Sephadex column (4 x 35 cm) equilibrated with 0.1% TFA.
- the eluant was monitored at 280 nm, and a 10 ⁇ L aliquot from each tube was used for the alkalinization response assay using 2 ml cells for each assay.
- fractions were assayed by alkalinization of tobacco cell culture medium. Fractions 61-62 were active and were pooled and lyophilized. Peak II was eluted with the same buffer system as peak I, but with a 90 min gradient to 100% B. The active fractions, 56 and 57, were pooled and lyophilized.
- the two active peaks were solubilized in 1 ml 0.1 % TFA each and injected into a narrow bore reversed-phase C18 column (Vydac, Column 218TP52, 2.1 by 250 mm, 5 ⁇ m beads, 300 angstrom pores).
- Solvent A consisted of 0.1% TFA in water, and solvent B was 0.05% TFA in methanol. Samples were injected in solvent A, and after 2 minutes, a 90 minute gradient from 0% solvent B to 30% solvent B was applied. The flow rate was 0.25 ml/min and the fractions (0.25 ml) were monitored at 214 nm and 2 ⁇ l were assayed for their alkalinization activity in tobacco cell cultures.
- the elution and alkalinization profiles for peak I activity are shown in FIGURE 3A and FIGURE 3B, respectively.
- the elution and alkalinization profile for peak II activity are shown in FIGURE 4A and FIGURE 4B. respectively.
- the purified polypeptides were sequenced and named tobacco systemin I (peak I activity) (SEQ ID NO: 1) and tobacco systemin II (peak II activity) (SEQ ID NO: 2). Both are polypeptides of 18 amino acids and both are glycosylated. Using mild acid hydrolysis, the carbohydrates were removed, and the masses of both tobacco systemin I (SEQ ID NO: 1) and tobacco systemin II (SEQ ID NO: 2) were analyzed before and after acid hydrolysis using a MALDI-MS.
- the amino acid sequence of tobacco systemin I is NH 2 -RGANLPXXSXASSXXSKE-COO. (SEQ ID NO: l).
- the amino acid sequence of tobacco systemin II is NH 2 -
- NRKPLSXXSXKPADGQRP-COO (SEQ ID NO:2).
- the one letter abbreviation "X" represents hydroxyproline.
- the masses after acid hydrolysis exactly matched the masses obtained by sequence analysis. The loss of carbohydrate indicated that 9 pentose units were present in tobacco systemin I (SEQ ID NO: 1), while 6 units were in tobacco systemin II (SEQ ID NO: 2). Both peaks were active at low picomole levels in inducing tobacco proteinase inhibitor protein to accumulate when supplied to young tobacco plants through their cut stems, and in causing the alkalinization of tobacco suspension cell cultures (Table 1).
- the potency of the tobacco systemins was similar to that found for tomato systemin (disclosed in U.S. Patent Serial Number 5,378,819) in its alkalinization response in tomato cell suspension cultures and in inducing proteinase inhibitors in leaves of excised tomato plants (Table 1). TABLE 1
- EXAMPLE 2 Identification and Isolation of a 5 kDa Polypeptide From Tobacco that is Regulated by Cvtokinins During the isolation of tobacco systemin I (SEQ ID NO: 1) and tobacco systemin II (SEQ ED NO: 2) described in Example 1 herein, fractions eluting much later than the two systemins were found to exhibit a strong alkalinization response (FIGURES 5 and 6). This peak was easily purified in a similar manner as described above for tobacco systemins I (SEQ ID NO: 1) and II (SEQ ID NO: 2). Sequence analysis and mass spectral analyses of the fraction revealed that it was a 5 kDa polypeptide.
- the pure polypeptide is more active (active at low pmole levels) than tobacco systemins (SEQ ED NO: 1 and SEQ ED NO: 2) in the liquid plant cell culture alkalinization assay, and it induces MAP kinase activities similar to systemins (see Example 5 below). However, it does not induce proteinase inhibitors in tobacco, indicating that it is not a systemin, but a new class of polypeptide signal in plants.
- FIGURES 7A and 7B show the alkalinization profiles of extracts from flower buds and leaves, respectively, of young tobacco plants using N. tabacum suspension cultured cells. The extracts were taken through the same purification steps as the tobacco extracts shown in FIGURE 2 that were used for tobacco systemin isolation. It can be seen that several peaks of activity are detected, some strong responses, others weak. These peaks can be readily isolated and characterized
- Cell suspension cultures useful in the methods of the invention can be prepared in the following manner.
- the initial cells are obtained from clean tissue, such as seeds (such as tomato, tobacco, potato, Arabidopsis and alfalfa seeds).
- the seeds are soaked in 50% bleach, 0.1% wetting agent (such as Tween 20), for 30 minutes (or for 45 minutes if the seeds appear to be dirty).
- the seeds are plated out on MSB medium for germination.
- explants can be cut from a desired tissue type (e.g., cotyledons, hypocotyls or roots) or the seedlings can be cut up into 4-5 mm long pieces with a scalpel.
- the cut tissue is plated onto MST-12 medium.
- the composition of MSB medium is: MS salts, ⁇ itsch vitamins, 3% sucrose, 0.8% agar (pH 5.8).
- the composition of MST-12 medium is the same as MSB medium but with the addition of 0.1 mg/L benzyl adenine, 2.0 mg/L 2,4-D, 1 to 2 grams of casein hydrolysate (pH 5.8).
- the cells can be maintained in 125 mL Ehrlenmeyer flasks on an orbital shaker (160 rpm) under constant light. Three milliliters of cells are subcultured every seven days into 45 mL of sterile media (unbuffered, pH 5.5 adjusted with 0.1 M KOH) containing 3% sucrose, 4.3 g/L Murashige and Skoog salt mixture, 5 mg/L 1-napthylacetic acid, 2 mg/L 6-benzylaminopurine, 110 mg/L ⁇ itsch and ⁇ itsch vitamin powder, 1 mg/L thiamine, 100 mg/L myo-inositol and 1 mM EDTA. Cells can be used for alkalinization assays from 4 to 8 days after subculturing.
- a representative tomato cell line useful in the practice of the present invention is Lycopersicon peruvianum cell line Msk8.
- EXAMPLE 5 MAP Kinase Activation of Tobacco Systemin I (SEQ ID NO: 1), Tobacco Systemin II (SEQ ID NO: 2) and the 5 kDa Polypeptide The ability of tobacco systemin I (SEQ ID NO: 1), tobacco systemin II (SEQ ED NO: 2) and the 5 kDa polypeptide, described in Example 2 herein, to stimulate the phosphorylation of a MAP kinase protein in tobacco leaf extracts was investigated.
- the MAP kinase assay utilized was essentially as described in Stratmann, J.W. and Ryan, C.A., Proc. Nat'l. Acad. Sci. U.S.A. 94: 11085-11089 (1997), which publication is incorporated herein by reference.
- Tobacco systemin II (SEQ ED NO: 2) and the 5 kDa polypeptide each possess MAP kinase stimulating activity.
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CA002400390A CA2400390A1 (en) | 2000-02-15 | 2001-02-13 | Methods for identifying signalling molecules |
EP01912797A EP1294932A1 (en) | 2000-02-15 | 2001-02-13 | Methods for identifying signalling molecules |
AU2001241542A AU2001241542A1 (en) | 2000-02-15 | 2001-02-13 | Methods for identifying signalling molecules |
US10/204,341 US20030211941A1 (en) | 2001-02-13 | 2001-02-13 | Methods for identifying signalling molecules |
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US18308900P | 2000-02-15 | 2000-02-15 | |
US18307300P | 2000-02-15 | 2000-02-15 | |
US60/183,089 | 2000-02-15 | ||
US60/183,073 | 2000-02-15 |
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WO2001061047A1 true WO2001061047A1 (en) | 2001-08-23 |
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PCT/US2001/005191 WO2001061047A1 (en) | 2000-02-15 | 2001-02-13 | Methods for identifying signalling molecules |
PCT/US2001/005241 WO2001060972A2 (en) | 2000-02-15 | 2001-02-15 | Novel peptides and methods of use |
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PCT/US2001/005241 WO2001060972A2 (en) | 2000-02-15 | 2001-02-15 | Novel peptides and methods of use |
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EP (2) | EP1294932A1 (en) |
AU (2) | AU2001241542A1 (en) |
CA (2) | CA2400390A1 (en) |
WO (2) | WO2001061047A1 (en) |
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EP1669456A3 (en) | 2004-12-11 | 2006-07-12 | SunGene GmbH | Expression cassettes for meristem-preferential expression in plants |
WO2014006452A2 (en) * | 2012-07-04 | 2014-01-09 | Universidade De São Paulo - Usp | Rapid alkalinization factor peptides for delivery of nucleic acid molecules into cells |
CN113583097B (en) * | 2021-05-25 | 2024-03-29 | 湖南大学 | CtRALF protein, ctRALF gene, primer, prokaryotic expression vector and application thereof |
Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
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US4743287A (en) * | 1984-09-24 | 1988-05-10 | Robinson Elmo C | Fertilizer and method |
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EP1033405A3 (en) * | 1999-02-25 | 2001-08-01 | Ceres Incorporated | Sequence-determined DNA fragments and corresponding polypeptides encoded thereby |
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2001
- 2001-02-13 EP EP01912797A patent/EP1294932A1/en not_active Withdrawn
- 2001-02-13 AU AU2001241542A patent/AU2001241542A1/en not_active Abandoned
- 2001-02-13 WO PCT/US2001/005191 patent/WO2001061047A1/en not_active Application Discontinuation
- 2001-02-13 CA CA002400390A patent/CA2400390A1/en not_active Abandoned
- 2001-02-15 EP EP01912809A patent/EP1309608A2/en not_active Withdrawn
- 2001-02-15 CA CA002400277A patent/CA2400277A1/en not_active Abandoned
- 2001-02-15 WO PCT/US2001/005241 patent/WO2001060972A2/en not_active Application Discontinuation
- 2001-02-15 AU AU2001241554A patent/AU2001241554A1/en not_active Abandoned
Patent Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
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US4743287A (en) * | 1984-09-24 | 1988-05-10 | Robinson Elmo C | Fertilizer and method |
Also Published As
Publication number | Publication date |
---|---|
EP1309608A2 (en) | 2003-05-14 |
WO2001060972A2 (en) | 2001-08-23 |
AU2001241542A1 (en) | 2001-08-27 |
WO2001060972A3 (en) | 2003-01-03 |
EP1294932A1 (en) | 2003-03-26 |
CA2400390A1 (en) | 2001-08-23 |
CA2400277A1 (en) | 2001-08-23 |
AU2001241554A1 (en) | 2001-08-27 |
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