Solution structure of a C-terminal coiled-coil domain from bovine IF1: Theinhibitor protein of F-1 ATPase

Bovine IF1 is a basic, 84 amino acid residue protein that inhibits the hydr olytic action of the F1F0 ATP synthase in mitochondria under anaerobic cond itions. Its oligomerization state is dependent on pH. At a pH value below 6 .5 it forms an active dimer. At higher pH values, two dimers associate to f orm an inactive tetramer. Here, we present the solution structure of a C-te rminal fragment of IF1 (44-84) containing all fire of the histidine residue s present in the sequence. Most unusually, the molecule forms an anti-paral lel coiled-coil in which three of the five histidine residues occupy key po sitions at the dimer interface. (C) 2001 Academic Press.