Bacillus cereus-type polyhydroxyalkanoate biosynthetic gene cluster contains R-specific enoyl-CoA hydratase gene |
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Authors: | Takahiro Kihara Ayaka Hiroe Manami Ishii-Hyakutake Kouhei Mizuno |
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Institution: | 1. Department of Materials Science and Engineering, Tokyo Institute of Technology, Midori-ku, Yokohama, Japan;2. Department of Innovative and Engineered Materials, Tokyo Institute of Technology, Midori-ku, Yokohama, Japan;3. Bioplastic Research Team, RIKEN Biomass Engineering Program, Wako-shi, Saitama, Japan;4. Department of Creative Engineering, National Institute of Technology, Kitakyushu College, Kitakyushu, Japan |
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Abstract: | Bacillus cereus and Bacillus megaterium both accumulate polyhydroxyalkanoate (PHA) but their PHA biosynthetic gene (pha) clusters that code for proteins involved in PHA biosynthesis are different. Namely, a gene encoding MaoC-like protein exists in the B. cereus-type pha cluster but not in the B. megaterium-type pha cluster. MaoC-like protein has an R-specific enoyl-CoA hydratase (R-hydratase) activity and is referred to as PhaJ when involved in PHA metabolism. In this study, the pha cluster of B. cereus YB-4 was characterized in terms of PhaJ’s function. In an in vitro assay, PhaJ from B. cereus YB-4 (PhaJYB4) exhibited hydration activity toward crotonyl-CoA. In an in vivo assay using Escherichia coli as a host for PHA accumulation, the recombinant strain expressing PhaJYB4 and PHA synthase led to increased PHA accumulation, suggesting that PhaJYB4 functioned as a monomer supplier. The monomer composition of the accumulated PHA reflected the substrate specificity of PhaJYB4, which appeared to prefer short chain-length substrates. The pha cluster from B. cereus YB-4 functioned to accumulate PHA in E. coli; however, it did not function when the phaJYB4 gene was deleted. The B. cereus-type pha cluster represents a new example of a pha cluster that contains the gene encoding PhaJ. |
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Keywords: | polyhydroxyalkanoate PhaJ R-specific hydratase monomer supplier |
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