Escherichia coli multiple [Ni-Fe]-hydrogenases are sensitive to osmotic stress during glycerol fermentation but at different pHs.
Escherichia coli evolves H2 via multiple [Ni-Fe]-hydrogenases (Hyd). This activity under hyper- and hypo-osmotic stress was investigated with mutants lacking different Hyd enzymes during glycerol fermentation. Inhibitory effects of hypo-stress on H2 production was stronger at pH 6.5 in wild type and mutants except fhlA, which encodes a transcriptional activator for Hyd-3, compared with the effects of N,N'-dicyclohexylcarbodiimide. These results indicate that Hyd-3 and Hyd-4 are osmosensitive at pH 7.5. Hyd-4 and FhlA are implicated in osmotic stress response at pH 6.5. Hyd-1 and FhlA might be osmosensitive at pH 5.5. Thus, osmosensitivity of Hyd enzymes is a novel property that depends on pH. This is significant for mechanisms of cell osmoregulation and H2 production biotechnology when glycerol is used as a fermentation substrate.
Department of Biophysics, Yerevan State University, 0025 Yerevan, Armenia.
Karen
K
Trchounian
Armen
A
Trchounian
D004926:Escherichia coli / Q000201:enzymology* / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000378:metabolism; D005285:Fermentation; D005990:Glycerol / Q000378:metabolism*; D006859:Hydrogen / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D006864:Hydrogenase / Q000378:metabolism*; D064587:Osmoregulation; D009997:Osmotic Pressure; D015534:Trans-Activators / Q000378:metabolism
D029968:Escherichia coli Proteins; D015534:Trans-Activators; C067189:fhlA protein, E coli; D006859:Hydrogen; C043296:nickel-iron hydrogenase; D006864:Hydrogenase; D005990:Glycerol
Escherichia coli; FhlA; Glycerol fermentation; H(2) production; Osmotic stress; [Ni–Fe]-hydrogenases; pH