The oligomycin sensitivity conferring protein (OSCP) is a subunit of the mitochondrial ATP synthase (F0F1) required for the functional interaction of the F0 and F1 moieties. To gain insight into the role(s) of this protein, recombinant rat liver OSCP was generated and biochemically characterized One tight binding site for OSCP was identified on F1. Two charged residues (E91 and R94) which lie within the central region of OSCP and are conserved in all known OSCP proteins were mutated The recombinant proteins (E91Q, R94Q, and R94A) were purified to homogeneity and were found to be indistinguishable from wild type OSCP by SDS-PAGE, and exhibited circular dichroism spectra almost identical to the wild type protein. Both R94 mutants demonstrated little or no binding to FI, while the E91Q protein was shown to bind in a manner identical to wild type OSCP. Significantly, all three mutant proteins were able to reconstitute FI with membranes and to confer oligomycin sensitivity to the same extent as wild type OSCP. These results show that a single tight binding site exists on isolated rat liver FI for OSCP and implicate R94 as playing a critical role in this tight binding site. In addition, these results indicate that this tight binding site is not required for conferral of oligomycin sensitivity to the reconstituted F0F1 complex The structural and functional implications of these conclusions will be discussed.
|Original language||English (US)|
|State||Published - Dec 1 1998|
ASJC Scopus subject areas
- Molecular Biology