Essential role of ferrous iron in cyanide‐resistant respiration in Hansenula anomala

Antimycin A-dependent induction of cyanide-resistant respiration in Hansenula anomala was completely blocked by o-phenanthroline, alpha,alpha'-dipyridyl, or 8-hydroxyquinoline. Pulse-labeling of the cells with [35S]methionine in the presence of both antimycin A and o-phenanthroline indicated that the 36-kDa protein previously reported to be involved in cyanide-resistant respiration [(1989) J. Biochem. 105, 864-866] was formed in mitochondria even under these conditions. The addition of Fe2+, but not Fe3+, ions to these cells in the presence of cycloheximide resulted in the rapid expression of cyanide-resistant respiration activity. These results suggest that in the presence of both antimycin A and o-phenanthroline an inactive form of the 36-kDa protein was formed and Fe2+ ions converted it to the active form. It is also likely that Fe2+ ions are involved in the reaction mechanism of cyanide-resistant respiration.