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Hyper-inducible expression system for streptomycetes.

ABSTRACT: Streptomycetes produce useful enzymes and a wide variety of secondary metabolites with potent biological activities (e.g., antibiotics, immunosuppressors, pesticides, etc.). Despite their importance in the pharmaceutical and agrochemical fields, there have been no reports for practical expression systems in streptomycetes. Here, we developed a "P(nitA)-NitR" system for regulatory gene expression in streptomycetes based on the expression mechanism of Rhodococcus rhodochrous J1 nitrilase, which is highly induced by an inexpensive and safe inducer, epsilon-caprolactam. Heterologous protein expression experiments demonstrated that the system allowed suppressed basal expression and hyper-inducible expression, yielding target protein levels of as high as approximately 40% of all soluble protein. Furthermore, the system functioned in important streptomycete strains. Thus, the P(nitA)-NitR system should be a powerful tool for improving the productivity of various useful products in streptomycetes.

SUBMITTER: Herai S

PROVIDER: S-EPMC521115 | biostudies-literature | 2004 Sep

REPOSITORIES: biostudies-literature

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Hyper-inducible expression system for streptomycetes.

Herai Sachio S Hashimoto Yoshiteru Y Higashibata Hiroki H Maseda Hideaki H Ikeda Haruo H Omura Satoshi S Kobayashi Michihiko M

Proceedings of the National Academy of Sciences of the United States of America 20040917 39

Streptomycetes produce useful enzymes and a wide variety of secondary metabolites with potent biological activities (e.g., antibiotics, immunosuppressors, pesticides, etc.). Despite their importance in the pharmaceutical and agrochemical fields, there have been no reports for practical expression systems in streptomycetes. Here, we developed a "P(nitA)-NitR" system for regulatory gene expression in streptomycetes based on the expression mechanism of Rhodococcus rhodochrous J1 nitrilase, which is ...[more]

PMID: 15377796

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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.

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Hyper-inducible expression system for streptomycetes.

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Hyper-inducible expression system for streptomycetes.

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