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Influence of C 4 ‐Dcu transporters on hydrogenase and formate dehydrogenase activities in stationary phase‐grown fermenting Escherichia coli
Author(s) -
Karapetyan Lusine,
Pinske Constanze,
Sawers Gary,
Trchounian Armen,
Trchounian Karen
Publication year - 2020
Publication title -
iubmb life
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.132
H-Index - 113
eISSN - 1521-6551
pISSN - 1521-6543
DOI - 10.1002/iub.2290
Subject(s) - fermentation , mixed acid fermentation , biochemistry , escherichia coli , glycerol , chemistry , mutant , wild type , formate , bacteria , biology , lactic acid , lactic acid fermentation , gene , genetics , catalysis
During mixed‐acid fermentation, Escherichia coli transports succinate mainly via transporters of the Dcu family. Here, we analyze the influence of Dcu transporters on hydrogenase (Hyd) and fermentative formate dehydrogenase (FDH‐H) activities and how this is affected by external pH and carbon source. Using selected dcu mutations, it was shown that Dcu carriers mainly affect Hyd and FDH‐H activities during glycerol but not glucose fermentation at acidic pH. During glycerol fermentation at pH 5.5, inactivation of either one or all Dcu carriers increased total Hyd activity by 60% compared with wild type. Under the same growth conditions, a dcuACBD mutant had a twofold higher FDH‐H activity. When glucose was fermented in dcuD single mutant at pH 5.5, the FDH‐H activity was also increased twofold compared with wild type. Interestingly, in dcuD or dcuACBD mutants at pH 7.5, Hyd activity was lowered by 20%. Taken together, it can be concluded that during glucose fermentation at pH 7.5, lack of DcuD affects Hyd enzyme activity, but at pH 5.5, it has a stronger effect on FDH‐H activity. During glycerol fermentation, lack of Dcu carriers increased Hyd and FDH‐H activities as revealed at pH 5.5. The results suggest that impairing Dcu transport function increases intracellular formate levels and thus affects H 2 cycling and proton‐motive force generation.