Upon fermentation, Escherichia coli carries out an exchange of 2H+ from the cytoplasm by one K+ of the external medium through the supercomplex of the F0F1 ATPase and TrkA system of K+ uptake. This bacterium produces also H2 via formate hydrogenlyase. It has been shown that reducer of disulphide groups DL-dithiothreitol (DTT) accelerates, while impermeable oxidizer ferricyanide inhibits the 2H+/K+-exchange by these bacteria; change in the production of H2 is simultaneously observed. The formation of H2 is detected in protoplasts with increased membrane permeability in gradient-less conditions when formate or NADH is added. This is not observed in the presence of N-ethylmaleimide and N,N'-dicyclohexylcarbodiimide (DCCD). ATP increases the amount of accessible SH-groups in membrane vesicles. DTT induces an additional increase, but DCCD and ferricyanide eliminate these effects. Upon substitution of all native cysteines in F0F1 by alanines in the mutant strain the DCCD-sensitive K+ uptake is observed. However, it is different from that in the precursor strain. In this case production of H2 is not detected. The amount of accessible SH-groups in this mutant is lowered and it does not depend on ATP. The results point to the involvement of SH-groups in the operation of supercomplex of F0F1 and TrkA. They can be explained by the model of dithiol-disulphide transitions. Formate, which is oxidized by formate hydrogenlyase, may serve as a donor of oxidation-reduction equivalents used for dithiol-disulphide interchange in the supercomplex. The results also indicate that at least one of cysteine residues of F0F1 is required for its operation. This cysteine participates in dithiol-disulphide interchange by interaction of F0F1 with TrkA or with formate hydrogenlyase.
|Original language||English (US)|
|Number of pages||10|
|State||Published - 2002|
All Science Journal Classification (ASJC) codes
- Molecular Biology
- Cell Biology