Respiration-linked proton flux in Wolinella succinogenes during reduction of N-oxides.
Formate uncoupled proton translocation in formate-grown Wolinella succinogenes cells supplied with N-oxides as terminal electron acceptors. In suspensions containing KSCN (but not valinomycin), H2 supported proton translocation when NO3-, NO2-, and NO were provided as oxidants. H+/N-oxide ratios were 4.77 for NO3-, 2.49 for NO2-, and 1.75 for NO. KSCN inhibits N2O reduction thus precluding use of N2O as oxidant. Repeated exposure of cells to NO inhibited their ability to translocated protons with NO as oxidant but only slightly diminished and did not eliminate their capacity for NO3(-)- or NO2(-)-dependent proton flux. Substituting reduced benzyl viologen for H2 and measuring proton uptake provided results consistent with an extramembranal location for the N- oxide reductases. The uncoupler, carbonyl cyanide m-chlorophenylhydrazone, collapsed proton gradients, permitted uptake of 2 mol H+/mol NO3- or NO2-, but unaccountably inhibited NO3- reduction by 50% while leaving H+ uptake stoichiometry of the cells unaffected.
D001419:Bacteria / Q000378:metabolism; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone / Q000494:pharmacology; D004579:Electron Transport; D009589:Nitrogen Oxides / Q000378:metabolism*; D010084:Oxidation-Reduction; D010101:Oxygen Consumption; D011522:Protons
D009589:Nitrogen Oxides; D011522:Protons; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone