Open AccessBiosynthesis of poly‐β‐hydroxybutyrate (PHB) is controlled by CydR (Fnr) in the obligate aerobe Azotobacter vinelandii
Author(s) -
Wu Guanghui,
Moir Arthur J.G,
Sawers Gary,
Hill Susan,
Poole Robert K
Publication year - 2001
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.2001.tb09472.x
Subject(s) - azotobacter vinelandii , mutant , biochemistry , reductase , azotobacter chroococcum , biology , azotobacteraceae , biosynthesis , oxidase test , enzyme , chemistry , bacteria , nitrogenase , nitrogen fixation , gene , genetics
CydR is an Fnr‐like protein in the obligatory aerobic nitrogen‐fixing bacterium Azotobacter vinelandii . The cydR mutant overproduces the cytochrome bd terminal oxidase. Using two‐dimensional polyacrylamide gel electrophoresis, we showed that β‐ketothiolase and acetoacetyl‐CoA reductase were also overexpressed in the cydR mutant. Fumarase C and a coenzyme A transferase, possibly succinyl‐SCoA transferase, were decreased in this mutant. Enzyme assays confirmed the elevated β‐ketothiolase and acetoacetyl‐CoA reductase activities in this mutant. The cydR mutant accumulated poly‐β‐hydroxybutyrate throughout the exponential growth phase, unlike the wild‐type strain that only accumulated poly‐β‐hydroxybutyrate during stationary phase. The results demonstrate that CydR controls poly‐β‐hydroxybutyrate synthesis in A. vinelandii .