Disclosure of Invention
In order to solve the problems, the extracellular expression of the pullulanase is further improved, and the extracellular expression of the pullulanase can be improved by means of synonymous mutation. Synonymous mutations in a gene may leave the amino acid sequence unchanged, but may result in significant changes in the level of gene transcription. The N-terminal coding region of the gene is modified by a synonymous mutation means, so that the gene expression level can be remarkably improved, and the influence on the enzyme activity can be almost ignored. According to the invention, the extracellular enzyme activity of the pullulanase can be obviously improved by using the signal peptide screened by the synonymous mutation.
The invention provides a signal peptide, wherein the nucleotide sequence of the signal peptide is shown in any one of SEQ ID No. 1-3.
In one embodiment of the invention, the nucleotide sequence of the signal peptide is the signal peptide AprE, SacB, Epr synonymous mutant sequence, respectively.
In one embodiment of the invention, the synonymous mutant sequence of the signal peptide AprE is shown as SEQ ID No. 1; the synonymous mutation sequence of the signal peptide SacB is shown as SEQ ID NO. 2; the synonymous mutant sequence of the signal peptide Epr is shown as SEQ ID NO. 3.
The invention provides a recombinant plasmid containing a signal peptide with a nucleotide sequence shown as SEQ ID No. 1-3.
In one embodiment of the present invention, the heavy plasmid is any vector that can be expressed in Bacillus subtilis.
In one embodiment of the invention, the starting vector comprises P43 NMK.
In one embodiment of the present invention, the recombinant plasmid further comprises a constitutive promoter.
In one embodiment of the invention, the constitutive promoter comprises a LytR promoter, and the nucleotide sequence of the LytR promoter is shown in SEQ ID No. 4.
The invention provides a recombinant bacterium containing a signal peptide with a nucleotide sequence shown as SEQ ID No. 1-3.
In one embodiment of the present invention, the recombinant bacterium is a bacillus subtilis host.
In one embodiment of the present invention, the recombinant bacterium is a host bacillus subtilis WB600 or bacillus subtilis 168.
The invention provides a method for improving protein expression quantity, which takes a recombinant strain containing a signal peptide with a nucleotide sequence shown as SEQ ID No. 1-3 as a fermentation strain to produce protein.
In one embodiment of the present invention, the recombinant bacterium is cultured to OD600And (3) inoculating the bacterial liquid not lower than 3.0 into the reaction system according to the proportion of 1-10 mL/100 mL.
In one embodiment of the present invention, the culture medium of the culture system is TB culture medium, and the TB culture medium is cultured at 30-40 ℃ and 200-250 rpm for 25-35 hours.
The invention provides a method for improving the extracellular protein expression quantity of bacillus subtilis, which adds a signal peptide with a nucleotide sequence shown as SEQ ID NO. 1-3 at the N end of a nucleotide sequence of a coded protein.
In one embodiment of the invention, a signal peptide with a nucleotide sequence shown in SEQ ID No. 1-3 is added to the N-terminal of a target protein, a recombinant plasmid is constructed, and the recombinant plasmid is introduced into Bacillus subtilis.
In one embodiment of the present invention, a signal peptide having a nucleotide sequence represented by SEQ ID NO.1 to 3 is inserted after the initiation codon ATG of a nucleotide sequence encoding a target protein.
In one embodiment of the invention, the protein of interest is any protein that can be expressed extracellularly in B.subtilis.
In one embodiment of the invention, the protein of interest comprises pullulanase and/or sfGFP.
In one embodiment of the invention, the amino acid sequence of pullulanase has NCBI accession number AMQ67157 and the amino acid sequence is shown in SEQ ID NO. 5.
In one embodiment of the invention, the nucleotide sequence encoding sfGFP is shown in SEQ ID No. 7.
The invention also protects the application of the signal peptide with the nucleotide sequence shown in SEQ ID NO. 1-3, or the recombinant plasmid containing the signal peptide with the nucleotide sequence shown in SEQ ID NO. 1-3, or the recombinant bacterium containing the signal peptide with the nucleotide sequence shown in SEQ ID NO. 1-3 in improving the expression quantity of extracellular proteins.
The invention also protects the application of the method for improving the protein expression quantity in improving the extracellular protein expression quantity.
The invention also protects the application of the method for improving the extracellular protein expression quantity of the bacillus subtilis in improving the extracellular protein expression quantity.
The invention also protects the application of the recombinant plasmid, the recombinant bacterium or the synonymous mutant sequence of the signal peptides AprE, SacB and Epr in improving the expression quantity of extracellular proteins.
The invention has the beneficial effects that:
the signal peptides AprE, SacB and Epr are subjected to synonymous mutation, so that a synonymous mutation sequence capable of improving the extracellular expression of the protein is screened out, the obtained mutation sequence is fused at the N end of the pullulanase, the extracellular enzyme activity yield of the pullulanase can be obviously improved and reduced, and the extracellular enzyme activity of the pullulanase is respectively improved by 2.92, 1.08 and 1.37 times in the conversion production of bacillus subtilis.
Example 5: application of synonymous mutation signal peptide in improvement of extracellular expression of pullulanase
Plasmids were extracted from the sequenced cells having the highest fluorescence intensity obtained in example 4, and sfGFP fluorescent proteins were removed using primers as templates, respectively, by PCR to obtain recombinant plasmids from which fluorescent proteins were removed, recombinant plasmids containing the synonymous mutation sequences for the aprE signal peptide, SacB signal peptide, and Epr signal peptide, respectively, were transformed into Bacillus subtilis WB600 to obtain recombinant bacteria, which were inoculated into 250mL shake flasks containing 20mL LB medium resistant to 50. mu.g/mL kanamycin,after fermentation at 37 ℃ for 8 hours at 220rpm, the OD was allowed to stand600The amount of pullulan was 4 or more, and the pullulan was inoculated into a 250mL shake flask containing 50. mu.g/mL kanamycin-resistant 25mL TB medium at a ratio of 4mL/100mL, and after 30 hours of fermentation at 37 ℃ and 250rpm, the extracellular enzyme activity of pullulanase was measured, and the results are shown in FIG. 3.
Removal of sfGFP forward primer:
CGGTAAAAAATAAtgagattatcaaaaaggatcttcacctagat(SEQ ID NO.18);
removal of sfGFP downstream primer:
gataatctcaTTATTTTTTACCGTGATCTGGAGAAACttc(SEQ ID NO.19)。
by measuring the extracellular enzyme activity of the pullulanase, the synonymous mutation sequences of Apre, Epr and SacB signal peptides are found to respectively improve the extracellular enzyme activity by 2.92, 1.08 and 1.37 times compared with the wild type.
TABLE 1 pullulanase extracellular enzyme Activity (U/mL)
Although the present invention has been described with reference to the preferred embodiments, it should be understood that various changes and modifications can be made therein by those skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.
SEQUENCE LISTING
<110> Jilin Mizhong Lianghua Co., Ltd
Jiangnan University
<120> Signal peptide for promoting extracellular expression of pullulanase
<160>19
<170>PatentIn version 3.3
<210>1
<211>84
<212>DNA
<213> Artificial sequence
<400>1
agaagtaaaa aattatggat aagtttatta tttgcgttaa cgttaatctt tacgatggcg 60
ttcagcaaca tgtctgcgca ggct 84
<210>2
<211>84
<212>DNA
<213> Artificial sequence
<400>2
aatataaaaa aatttgcaaa acaagctaca gtattaacct ttactaccgc actgctggca 60
ggaggcgcaa ctcaagcgtt tgcg 84
<210>3
<211>78
<212>DNA
<213> Artificial sequence
<400>3
aaaaatatgt cttgtaaact agttgtatct gtcactctgt ttttcagttt tctcaccata 60
ggccctctcg ctcatgcg 78
<210>4
<211>320
<212>DNA
<213> Artificial sequence
<400>4
ctaaccctac ataagtacct tcttttgttt caatgttact gtctggcgat acatcttcac 60
cttgactctt ttgactatta accccgcaac ccgaaagaag caatataaag aacagtaaag 120
caataaattt tttcattttt ttcacctcat tatattttat cgtcaaccta ttttatattt 180
taaagaaaaa ttaagaaaca atgaaacttt tttttataaa aaacgactat tttaggattt 240
cattcttgta ttaaatagag ttgtatttat tggaaattta actcataatg aaagtaattt 300
aaaggaggtg aaatgtacac 320
<210>5
<211>724
<212>PRT
<213> Artificial sequence
<400>5
Asp Ala Ala Lys Pro Ala Val Ser Asn Ala Tyr Leu Asp Ala Ser Asn
1 5 10 15
Gln Val Leu Val Lys Leu Ser Gln Pro Leu Thr Leu Gly Glu Gly Ala
20 2530
Ser Gly Phe Thr Val His Asp Asp Thr Ala Asn Lys Asp Ile Pro Val
35 40 45
Thr Ser Val Lys Asp Ala Ser Leu Gly Gln Val Glu Ser Gly Val Lys
50 55 60
Thr Asp Leu Val Thr Val Thr Leu Gly Glu Asp Pro Asp Val Ser His
65 70 75 80
Thr Leu Ser Ile Gln Thr Asp Gly Tyr Gln Ala Lys Gln Val Ile Pro
85 90 95
Arg Asn Val Leu Asn Ser Ser Gln Tyr Tyr Tyr Ser Gly Asp Asp Leu
100 105 110
Gly Asn Thr Tyr Thr Gln Lys Ala Thr Thr Phe Lys Val Trp Ala Pro
115 120 125
Thr Ser Thr Gln Val Asn Val Leu Leu Tyr Asp Ser Ala Thr Gly Ser
130 135 140
Val Thr Lys Ile Val Pro Met Thr Ala Ser Gly His Gly Val Trp Glu
145 150 155 160
Ala Thr Val Asn Gln Asn Leu Glu Asn Trp Tyr Tyr Met Tyr Glu Val
165 170 175
Thr Gly Gln Gly Ser Thr Arg Thr Ala Val Asp Pro Tyr Ala Thr Ala
180 185190
Ile Ala Pro Asn Gly Thr Arg Gly Met Ile Val Asp Leu Ala Lys Thr
195 200 205
Asp Pro Ala Gly Trp Asn Ser Asp Lys His Ile Thr Pro Lys Asn Ile
210 215 220
Glu Asp Glu Val Ile Tyr Glu Met His Val Arg Asp Phe Ser Ile Asp
225 230 235 240
Pro Asn Ser Gly Met Lys Asn Lys Gly Lys Tyr Leu Ala Leu Thr Glu
245 250 255
Lys Gly Thr Lys Gly Pro Asp Asn Val Lys Thr Gly Ile Asp Ser Leu
260 265 270
Lys Gln Leu Gly Ile Thr His Val Gln Leu Met Pro Val Phe Ala Ser
275 280 285
Asn Ser Val Asp Glu Thr Asp Pro Thr Gln Tyr Asn Trp Gly Tyr Asp
290 295 300
Pro Arg Asn Tyr Asp Val Pro Glu Gly Gln Tyr Ala Thr Asn Ala Asn
305 310 315 320
Gly Asn Ala Arg Ile Lys Glu Phe Lys Glu Met Val Leu Ser Leu His
325 330 335
Arg Glu His Ile Gly Val Asn Met Asp Val Val Tyr Asn His Thr Phe
340 345 350
Ala Thr Gln Ile Ser Asp Phe Asp Lys Ile Val Pro Glu Tyr Tyr Tyr
355 360 365
Arg Thr Asp Asp Ala Gly Asn Tyr Thr Asn Gly Ser Gly Thr Gly Asn
370 375 380
Glu Ile Ala Ala Glu Arg Pro Met Val Gln Lys Phe Ile Ile Asp Ser
385 390 395 400
Leu Lys Tyr Trp Val Asn Glu Tyr His Ile Asp Gly Phe Arg Phe Asp
405 410 415
Leu Met Ala Leu Leu Gly Lys Asp Thr Met Ser Lys Ala Ala Ser Glu
420 425 430
Leu His Ala Ile Asn Pro Gly Ile Ala Leu Tyr Gly Glu Pro Trp Thr
435 440 445
Gly Gly Thr Ser Ala Leu Pro Asp Asp Gln Leu Leu Thr Lys Gly Ala
450 455 460
Gln Lys Gly Met Gly Val Ala Val Phe Asn Asp Asn Leu Arg Asn Ala
465 470 475 480
Leu Asp Gly Asn Val Phe Asp Ser Ser Ala Gln Gly Phe Ala Thr Gly
485 490 495
Ala Thr Gly Leu Thr Asp Ala Ile Lys Asn Gly Val Glu Gly Ser Ile
500 505 510
Asn Asp Phe Thr Ser Ser Pro Gly Glu Thr Ile Asn Tyr Val Thr Ser
515 520 525
His Asp Asn Tyr Thr Leu Trp Asp Lys Ile Ala Leu Ser Asn Pro Asn
530 535 540
Asp Ser Glu Ala Asp Arg Ile Lys Met Asp Glu Leu Ala Gln Ala Val
545 550 555 560
Val Met Thr Ser Gln Gly Val Pro Phe Met Gln Gly Gly Glu Glu Met
565 570 575
Leu Arg Thr Lys Gly Gly Asn Asp Asn Ser Tyr Asn Ala Gly Asp Ala
580 585 590
Val Asn Glu Phe Asp Trp Ser Arg Lys Ala Gln Tyr Pro Asp Val Phe
595 600 605
Asn Tyr Tyr Ser Gly Leu Ile His Leu Arg Leu Asp His Pro Ala Phe
610 615 620
Arg Met Thr Thr Ala Asn Glu Ile Asn Ser His Leu Gln Phe Leu Asn
625 630 635 640
Ser Pro Glu Asn Thr Val Ala Tyr Glu Leu Thr Asp His Val Asn Lys
645 650 655
Asp Lys Trp Gly Asn Ile Ile Val Val Tyr Asn Pro Asn Lys Thr Val
660 665 670
Ala Thr Ile Asn Leu Pro Ser Gly Lys Trp Ala Ile Asn Ala Thr Ser
675 680 685
Gly Lys Val Gly Glu Ser Thr Leu Gly Gln Ala Glu Gly Ser Val Gln
690 695 700
Val Pro Gly Ile Ser Met Met Ile Leu His Gln Glu Val Ser Pro Asp
705 710 715 720
His Gly Lys Lys
<210>6
<211>2172
<212>DNA
<213> Artificial sequence
<400>6
gatgctgcta aaccagcagt ttctaacgct taccttgacg cttctaacca agttttagtt 60
aaattatctc aaccattaac attaggtgaa ggtgcttctg gtttcactgt acatgatgac 120
actgctaaca aagacatccc agtaacatct gtaaaagacg cttctttagg tcaagttgaa 180
tcaggtgtaa aaactgacct tgttactgtt actttaggcg aagatccaga tgtatctcac 240
actttatcta tccaaacaga cggttaccaa gctaaacaag taatcccacg taacgtactt 300
aactcttctc aatattacta ttctggtgat gatttaggaa acacatacac acaaaaagct 360
actactttca aagtttgggc tcctacatct actcaagtta acgtattgtt atacgattct 420
gctacaggta gcgttacaaa aatcgttcca atgacggctt caggtcacgg tgtttgggag 480
gctactgtta accaaaactt agaaaactgg tactacatgt acgaagtaac tggtcaaggt 540
tctacacgca ctgctgttga tccttacgct actgctatcg ctccaaacgg tacacgcggc 600
atgatcgtag atttagctaa aactgaccca gcaggttgga actctgataa acacattact 660
ccaaaaaaca ttgaagatga agttatctac gaaatgcacg tacgtgattt ctctatcgat 720
ccaaactcag gtatgaaaaa caaaggtaaa tacttagctc taactgaaaa aggcactaaa 780
ggtcctgata acgttaaaac aggtatcgac tctcttaagc aattaggtat tacacatgtt 840
caattaatgc cagttttcgc atctaactca gttgacgaaa ctgatccaac acaatacaac 900
tggggttacg acccacgtaa ctacgatgta ccagaaggtc aatatgcaac taacgctaac 960
ggtaacgcac gtattaaaga attcaaagaa atggttttat cactacaccg tgagcacatc 1020
ggtgttaaca tggacgttgt ttacaaccac acgttcgcta ctcaaatctc tgacttcgat 1080
aaaattgttc cagagtacta ttaccgcact gacgacgcag gtaactacac taacggttct 1140
ggtactggta acgaaattgc tgcagaacgt cctatggtgc aaaaattcat catcgatagc 1200
cttaaatact gggttaacga ataccacatt gacggcttcc gtttcgactt aatggcttta 1260
cttggtaaag acacaatgtc taaggctgct tctgagttac atgctatcaa cccaggtatt 1320
gctttatatg gcgaaccttg gactggtggt acaagcgctc ttcctgacga ccaactttta 1380
actaaaggtg cacaaaaagg catgggagta gctgtattca acgataacct tcgtaacgca 1440
ttagacggaa acgttttcga ttcttctgct caaggattcg caacaggagc tacaggtctg 1500
actgatgcta ttaaaaacgg agttgaagga tcaatcaacg atttcacttc ttctcctggc 1560
gaaacaatta actacgttac atcacacgat aactacactc tttgggacaa aatcgctttg 1620
tctaacccta acgactctga agcagatcgc atcaaaatgg atgagcttgc tcaagctgtt 1680
gttatgactt ctcaaggtgt acctttcatg caaggtggtg aagaaatgtt acgcactaaa 1740
ggtggtaacg ataacagcta taacgcgggt gatgctgtaa acgaattcga ctggtctcgt 1800
aaagctcaat accctgacgt tttcaactac tactcaggtt taatccacct tcgtcttgac 1860
catccagctt tccgtatgac aacagctaac gaaatcaact ctcaccttca attccttaac 1920
tcacctgaaa acacagtagc ttacgaactt actgaccacg taaacaaaga taaatggggt 1980
aacattatcg ttgtttacaa ccctaacaag actgtagcaa ctatcaactt accatctggt 2040
aaatgggcta tcaacgcaac tagcggtaaa gtaggtgaat ctacattagg tcaagctgaa 2100
ggatctgtac aagttcctgg tatttctatg atgatccttc accaagaagt ttctccagat 2160
cacggtaaaa aa 2172
<210>7
<211>717
<212>DNA
<213> Artificial sequence
<400>7
gtgagcaagg gcgaggagct gttcaccggg gtggtgccca tcctggtcga gctggacggc 60
gacgtaaacg gccacaagtt cagcgtgaga ggcgagggcg agggcgatgc caccaatggc 120
aagctgaccc tgaagttcat ctgcaccacc ggcaagctgc ccgtgccctg gcccaccctc 180
gtgaccaccc tgacctacgg cgtgcagtgc ttcagccgct accccgacca catgaagcgc 240
cacgacttct tcaagtccgc catgcccgaa ggctacgtcc aggagcgcac catcagtttc 300
aaggacgacg gcacatacaa gacccgcgcc gaggtgaagt tcgagggcga caccctggtg 360
aaccgcatcg agctgaaggg catcgacttc aaggaggacg gcaacatcct ggggcacaag 420
ctggagtaca acttcaacag ccacaacgtc tatatcacgg ccgacaagca gaagaacggc 480
atcaaggcca acttcaagat ccgccacaac gtggaggacg gcagcgtgca gctcgccgac 540
cactaccagc agaacacccc catcggcgac ggccccgtgc tgctgcccga caaccactac 600
ctgagcaccc agtccgtgct gagcaaagac cccaacgaga agcgcgatca catggtcctg 660
ctggagttcg tgaccgccgc cgggatcact cacggcatgg acgagctgta caagtaa 717
<210>8
<211>84
<212>DNA
<213> Artificial sequence
<400>8
agaagcaaaa aattgtggat cagcttgttg tttgcgttaa cgttaatctt tacgatggcg 60
ttcagcaaca tgtctgcgca ggct 84
<210>9
<211>84
<212>DNA
<213> Artificial sequence
<400>9
aacatcaaaa agtttgcaaa acaagcaaca gtattaacct ttactaccgc actgctggca 60
ggaggcgcaa ctcaagcgtt tgcg 84
<210>10
<211>78
<212>DNA
<213> Artificial sequence
<400>10
aaaaacatgt cttgcaaact tgttgtatca gtcactctgt ttttcagttt tctcaccata 60
ggccctctcg ctcatgcg 78
<210>11
<211>36
<212>DNA
<213> Artificial sequence
<400>11
gtgtacattt cacctccttt aaattacttt cattat 36
<210>12
<211>61
<212>DNA
<213> Artificial sequence
<400>12
atgagragya araarttrtg gathagyttr ttrtttgcgt taacgttaat ctttacgatg 60
g 61
<210>13
<211>64
<212>DNA
<213> Artificial sequence
<220>
<221>misc_feature
<222>(6)..(6)
<223>n is a, c, g, or t
<220>
<221>misc_feature
<222>(15)..(15)
<223>n is a, c, g, or t
<220>
<221>misc_feature
<222>(18)..(18)
<223>n is a, c, g, or t
<220>
<221>misc_feature
<222>(24)..(24)
<223>n is a, c, g, or t
<220>
<221>misc_feature
<222>(27)..(27)
<223>n is a, c, g, or t
<220>
<221>misc_feature
<222>(30)..(30)
<223>n is a, c, g, or t
<400>13
atgctnaara gracntcntt ygtntcntcn ttrttcatca gttcagctgt tttactatca 60
atct 64
<210>14
<211>61
<212>DNA
<213> Artificial sequence
<220>
<221>misc_feature
<222>(15)..(15)
<223>n is a, c, g, or t
<220>
<221>misc_feature
<222>(24)..(24)
<223>n is a, c, g, or t
<220>
<221>misc_feature
<222>(27)..(27)
<223>n is a, c, g, or t
<400>14
atgttraara argtnathtt rgcngcntty athttagtag gaagtacttt gggagctttt 60
a 61
<210>15
<211>30
<212>DNA
<213> Artificial sequence
<400>15
agaagtaaaa aattatggat aagtttatta 30
<210>16
<211>30
<212>DNA
<213> Artificial sequence
<400>16
aatataaaaa aatttgcaaa acaagctaca 30
<210>17
<211>30
<212>DNA
<213> Artificial sequence
<400>17
aaaaatatgt cttgtaaact agttgtatct 30
<210>18
<211>44
<212>DNA
<213> Artificial sequence
<400>18
cggtaaaaaa taatgagatt atcaaaaagg atcttcacct agat 44
<210>19
<211>40
<212>DNA
<213> Artificial sequence
<400>19
gataatctca ttatttttta ccgtgatctg gagaaacttc 40