HIPIP OXIDOREDUCTASE ACTIVITY IN MEMBRANES FROM AEROBICALLY GROWN CELLS OF THE FACULTATIVE PHOTOTROPH RHODOFERAX FERMENTANS

The role of the periplasmically located, water-soluble, HiPIP (high-po tential iron-sulfur protein) in the respiratory chain of the facultati ve phototroph Rhodoferax fermentans has been examined. The oxidized Hi PIP is reduced by succinate-dependent respiration via the bc(1) comple x, this reaction being inhibited by myxothiazol and/or stigmatellin. T he reduced HiPIP can be oxidized by the membrane-bound cytochrome oxid ase, this reaction being inhibited by 0.1 mM cyanide. We conclude that aerobically grown Rf. fermentans contains a redox chain in which HiPI P mediates electron transfer between the be, complex and the cb-type c ytochrome oxidase.