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Development of a Cold-Adapted Pseudoalteromonas Expression System for the Pseudoalteromonas Proteins Intractable for the Escherichia coli System.

ABSTRACT: Although the Escherichia coli expression system is the most commonly used expression system, some proteins are still difficult to be expressed by this system, such as proteins with high thermolability and enzymes that cannot mature by autoprocessing. Therefore, it is necessary to develop alternative expression systems. In this study, a cold-adapted Pseudoalteromonas expression system was developed. A shuttle vector was constructed, and a conjugational transfer system between E. coli and psychrophilic strain Pseudoalteromonas sp. SM20429 was established. Based on the shuttle vector, three reporter vectors were constructed to compare the strength of the cloned promoters at low temperature. The promoter of xylanase gene from Pseudoalteromonas sp. BSi20429 was chosen due to its high activity at 10-15°C. An expression vector pEV containing the chosen promoter, multiple cloning sites and a His tag was constructed for protein expression and purification. With pEV as expression vector and SM20429 as the host, a cold-adapted protease, pseudoalterin, which cannot be maturely expressed in E. coli, was successfully expressed as an active extracellular enzyme when induced by 2% oat spelt xylan at 15°C for 48 h. Recombinant pseudoalterin purified from the culture by Ni affinity chromatography had identical N-terminal sequence, similar molecular mass and substrate specificity as the native pseudoalterin. In addition, another two cold-adapted enzymes were also successfully expressed by this system. Our results indicate that this cold-adapted Pseudoalteromonas expression system will provide an alternative choice for protein expression, especially for the Pseudoalteromonas proteins intractable for the E. coli system.

SUBMITTER: Yu ZC

PROVIDER: S-EPMC4557933 | biostudies-literature | 2015

REPOSITORIES: biostudies-literature

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Development of a Cold-Adapted Pseudoalteromonas Expression System for the Pseudoalteromonas Proteins Intractable for the Escherichia coli System.

Yu Zi-Chao ZC Tang Bai-Lu BL Zhao Dian-Li DL Pang Xiuhua X Qin Qi-Long QL Zhou Bai-Cheng BC Zhang Xi-Ying XY Chen Xiu-Lan XL Zhang Yu-Zhong YZ

PloS one 20150902 9

Although the Escherichia coli expression system is the most commonly used expression system, some proteins are still difficult to be expressed by this system, such as proteins with high thermolability and enzymes that cannot mature by autoprocessing. Therefore, it is necessary to develop alternative expression systems. In this study, a cold-adapted Pseudoalteromonas expression system was developed. A shuttle vector was constructed, and a conjugational transfer system between E. coli and psychrop ...[more]

PMID: 26333173

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Project description:Cupriavidus necator strain A-04 has shown 16S rRNA gene identity to the well-known industrial strain C. necator H16. Nevertheless, the cell characteristics and polyhydroxyalkanoate (PHA) production ability of C. necator strain A-04 were different from those of C. necator H16. This study aimed to express PHA biosynthesis genes of C. necator strain A-04 in Escherichia coli via an arabinose-inducible expression system. In this study, the PHA biosynthesis operon of C. necator strain A-04, consisting of three genes encoding acetyl-CoA acetyltransferase (phaA A-04, 1182 bp, 40.6 kDa), acetoacetyl-CoA reductase (phaB A-04, 741 bp, 26.4 kDa) and PHB synthase Class I (phaC A-04, 1770 bp), was identified. Sequence analysis of the phaA A-04, phaB A-04, and phaCA-04 genes revealed that phaC A-04 was 99% similar to phaC H16 from C. necator H16. The difference in amino acid residue situated at position 122 of phaC A-04 was proline, whereas that of C. necator H16 was leucine. The intact phaCAB A-04 operon was cloned into the arabinose-inducible araBAD promoter and transformed into E. coli strains Top 10, JM109 and XL-1 blue. The results showed that optimal conditions obtained from shaken flask experiments yielded 6.1 ± 1.1 g/L cell dry mass (CDM), a PHB content of 93.3 ± 0.9% (w/w) and a productivity of 0.24 g/(L⋅h), whereas the wild-type C. necator strain A-04 accumulated 78% (w/w) PHB with a productivity of 0.09 g/(L⋅h). Finally, for the scaled-up studies, fed-batch cultivations by pH-stat control in a 5-L fermenter of E. coli strains XL1-Blue harboring pBAD/Thio-TOPO-phaCAB A-04 and pColdTF-phaCAB A-04 in MR or LB medium, leading to a PHB production of 31.4 ± 0.9 g/L at 54 h with a PHB content of 83.0 ± 3.8% (w/w), a CDM of 37.8 ± 1.2 g/L, a Y P/S value of 0.39 g PHB/g glucose and a productivity of 0.6 g PHB/(L⋅h) using pColdTF-phaCAB A-04 in MR medium. In addition, PHB production was 29.0 ± 1.1 g/L with 60.2 ± 2.3% PHB content in the CDM of 53.1 ± 1.0 g/L, a Y P/S value of 0.21 g PHB/g glucose and a productivity of 0.4 g PHB/(L⋅h) using pBAD/Thio-TOPO-phaCAB A-04 in LB medium. Thus, a relatively high PHB concentration and productivity were achieved, which demonstrated the possibility of industrial production of PHB.

Dataset Information

Development of a Cold-Adapted Pseudoalteromonas Expression System for the Pseudoalteromonas Proteins Intractable for the Escherichia coli System.

Publications

Development of a Cold-Adapted Pseudoalteromonas Expression System for the Pseudoalteromonas Proteins Intractable for the Escherichia coli System.

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