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The roles of hydrogenases 3 and 4, and the F 0 F 1 ‐ATPase, in H 2 production by Escherichia coli at alkaline and acidic pH
Author(s) -
Bagramyan Karine,
Mnatsakanyan Nelli,
Poladian Anna,
Vassilian Anait,
Trchounian Armen
Publication year - 2002
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(02)02555-3
Subject(s) - hydrogenase , operon , escherichia coli , formate dehydrogenase , formate , disproportionation , chemistry , atpase , biochemistry , stereochemistry , enzyme , catalysis , gene
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 CO 2 and H 2 during fermentative growth at low pH. Recently, an operon ( hyf ) encoding a potential second H 2 ‐evolving hydrogenase (Hyd‐4) 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 Hyd‐4, Fdh‐H and F 0 F 1 ‐ATPase‐dependent, and Fdh‐H activity was partially dependent on Hyd‐4 and F 0 F 1 ‐ATPase. These results suggest that, at slightly alkaline pH, H 2 production and Fdh‐H activity are dependent on both the F 0 F 1 ‐ATPase and a novel FHL, designated FHL‐2, which is composed of Hyd‐4 and Fdh‐H, and is driven by a proton gradient established by the F 0 F 1 ‐ATPase.