期刊
FEBS LETTERS
卷 516, 期 1-3, 页码 172-178出版社
ELSEVIER SCIENCE BV
DOI: 10.1016/S0014-5793(02)02555-3
关键词
hydrogenase; F0F1-ATPase; H-2 production; fermentation; Escherichia coli
The hyc operon of Escherichia coli encodes the H-2-evolving hydrogenase 3 (Hyd-3) complex that, in conjunction with formate dehydrogenase H (Fdh-H), constitutes a membrane-associated formate hydrogenlyase (FHL) catalyzing the disproportionation of formate to CO2 and H-2 during fermentative growth at low pH. Recently, an operon (hyf) encoding a potential second H-2-evolving hydrogenase (Hyd4) was identified in E. coli. In this study the roles of the hyc- and hyf-encoded systems in formate-dependent H-2 production and Fdh-H activity have been investigated. In cells grown on glucose under fermentative conditions at slightly acidic pH the production of H-2 was mostly Hyd-3- and Fdh-H-dependent, and Fdh-H activity was also mainly Hyd-3-dependent. However, at slightly alkaline pH, H-2, production was found to be largely Hyd4, Fdh-H and F0F1-ATPase-dependent, and Fdh-H activity was partially dependent on Hyd-4 and F0F1-ATPase. These results suggest that, at slightly alkaline pH, H-2 production and Fdh-H activity are dependent on both the F0F1-ATPase and a novel FHL, designated FHL-2, which is composed of Hyd-4 and Fdh-H, and is driven by a proton gradient establisbed by the F0F1-ATPase. (C) 2002 Published by Elsevier Science B.V. on behalf of the Federation of European Biochemical Societies.
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