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New fadB homologous enzymes and their use in enhanced biosynthesis of medium‐chain‐length polyhydroxyalkanoates in fadB mutant Escherichia coli
Author(s) -
Jae Park Si,
Yup Lee Sang
Publication year - 2004
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/bit.20065
Subject(s) - escherichia coli , mutant , polyhydroxyalkanoates , biochemistry , biosynthesis , enzyme , gene , recombinant dna , biology , strain (injury) , chemistry , microbiology and biotechnology , bacteria , genetics , anatomy
Recombinant Escherichia coli harboring the medium‐chain‐length (MCL) polyhydroxyalkanoate (PHA) synthase gene has been shown to accumulate MCL‐PHAs from fatty acids when FadB is inactive. However, the enzymes in fadB mutant E. coli responsible for channeling the β‐oxidation intermediates to PHA biosynthesis have not been fully elucidated. Only recently, two enzymes encoded by yfcX and maoC have been found to be partially responsible for this. In this study, we identified five new FadB homologous enzymes in E. coli : PaaG, PaaF, BhbD, SceH, and YdbU, by protein database search, and examined their roles in the biosynthesis of MCL‐PHAs in an fadB mutant E. coli strain. Coexpression of each of these genes along with the Pseudomonas sp. 61‐3 phaC2 gene did not allow synthesis of MCL‐PHA from fatty acid in recombinant E. coli W3110, which has a fully functional β‐oxidation pathway, but allowed MCL‐PHA accumulation in an fadB mutant E. coli WB101. In particular, coexpression of the paaG, paaF, and ydbU genes resulted in a MCL‐PHA production up to 0.37, 0.25, and 0.33 g/L, respectively, from 2 g/L of sodium decanoate, which is more than twice higher than that obtained with E. coli WB101 expressing only the phaC2 gene (0.16 g/L). These results suggest that the newly found FadB homologous enzymes, or at least the paaG, paaF, and ydbU genes, are involved in MCL‐PHA biosynthesis in an fadB mutant E. coli strain and can be employed for the enhanced production of MCL‐PHA. © 2004 Wiley Periodicals, Inc.