F-0 complex of the Escherichia coli ATP synthase - Not all monomers of the subunit c oligomer are involved in F-1 interaction
|ALPHA-SUBUNIT; Biochemistry & Molecular Biology; CROSS-LINKING; DELTA-SUBUNIT; EPSILON-SUBUNIT; Escherichia coli; F-1 interaction; F0F1-ATPase; H+-ATPASE; H+/ATP COUPLING RATIO; monoclonal antibodies; MONOCLONAL-ANTIBODIES; POLAR LOOP REGION; POLYCLONAL ANTIBODIES; subunit c; TRANSMEMBRANE HELIX
|EUROPEAN JOURNAL OF BIOCHEMISTRY
The antigenic determinants of mAbs against subunit c of the Escherichia coli ATP synthase were mapped by ELISA using overlapping synthetic heptapeptides. All epitopes recognized are located in the hydrophilic loop region and are as follows: 31-LGGKFLE-37, 35-FLEGAAR-41, 36-LEGAAR-41 and 36-LEGAARQ-42. Binding studies with membrane vesicles of different orientation revealed that all mAbs bind to everted membrane vesicles independent of the presence or absence of the F-1 part. Although the hydrophilic region of subunit c and particularly the highly conserved residues A40, R41, Q42 and P43 are known to interact with subunits gamma and epsilon of the F-1 part, the mAb molecules have no effect on the function of F-0. Furthermore, it could be demonstrated that the F-1 part and the mAb molecule(s) are bound simultaneously to the F-0 complex suggesting that not all c subunits are involved in F-1 interaction. From the results obtained, it can be concluded that this interaction is fixed, which means that subunits gamma and epsilon do not switch between the c subunits during catalysis and furthermore, a complete rotation of the subunit c oligomer modified with mAb(s) along the stator of the F1F0 complex, proposed to be composed of at least subunits b and delta, seems to be unlikely.
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checked on Mar 3, 2024