LOCALIZATION OF CYANIDE-RESISTANT OXIDASE IN MITOCHONDRIA OF THE YEAST YARROWIA-LIPOLYTICA

Localization of cyanide-resistant oxidase in the inner membrane of mitochondria of the yeast Yarrowia lipolytica was studied using iron-chelating compounds with different hydrophobicity and artificial electron accepters. The activity of cyanide-resistant oxidation pathway was shown to be blocked by such hydrophobic compounds as benzohydroxamic acid (BHA), bathophenanthroline, and thenoyltrifluoroacetone (TTFA). These compounds were less effective with submitochondrial particles (SMP). The inhibitory effect produced by less hydrophobic bathophenanthroline sulfonate on the activity of cyanide insensitive mitochondrial oxidase was weak, especially in SMP. Hydrophilic potassium thiocyanate did not inhibit the activity of cyanide-resistant oxidase of mitochondria and SMP. Ferricyanide, which is unable to penetrate the inner mitochondrial membrane, did not accept electrons from cyanide-resistant oxidase of mitochondria and SMP. 2,6-Dichlorophenol-indophenol (DCPIP) prevented oxygen consumption by the alternative oxidase. It is concluded that cyanide-resistant oxidase is an integral protein of the inner mitochondrial membrane.