Electron-transfer restoration by vitamin K3 in a complex III-deficient mutant of S. cerevisiae and sequence of the corresponding cytochrome b mutation.
The yeast box-mutant W7 exhibits deficiencies in cytochrome b and in nuclear coded complex III subunits, a phenotype observed previously in a patient with mitochondrial myopathy. DNA sequence analysis of mutant W7 revealed a single base transition in the cytochrome b gene; the mutated residue Gly 131 is perfectly conserved in all known cytochromes b and belongs to the Qo domain. Mutant W7 provides a model system for evaluating the action of therapeutic agents, such as vitamin K3 which restored NADH-oxidase activity in the mutant as well as in the antimycin-inhibited wild type. However, with the mutant, a greater quantity of menadione was necessary due to a decrease in other complex activities, and a much lower electron-flow fraction passed through cytochrome oxidase.
Brivet-Chevillotte
P
P
Laboratoire de Chimie Bactérienne, CNRS, Marseille, France.
di Rago
J P
JP
D001483:Base Sequence; D003573:Cytochrome b Group / Q000378:metabolism*; D004247:DNA / Q000032:analysis; D004579:Electron Transport; D003576:Electron Transport Complex IV / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D005091:Exons; D008928:Mitochondria / Q000201:enzymology; D009097:Multienzyme Complexes / Q000378:metabolism; D009154:Mutation; D009247:NADH, NADPH Oxidoreductases / Q000378:metabolism; D010088:Oxidoreductases / Q000378:metabolism*; D012333:RNA, Messenger / Q000032:analysis; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000235:genetics; D013384:Succinate Cytochrome c Oxidoreductase / Q000378:metabolism*; D014812:Vitamin K / Q000494:pharmacology*
D003573:Cytochrome b Group; D009097:Multienzyme Complexes; D012333:RNA, Messenger; D014812:Vitamin K; D004247:DNA; D010088:Oxidoreductases; D013384:Succinate Cytochrome c Oxidoreductase; C023107:NADH oxidase; D009247:NADH, NADPH Oxidoreductases; D003576:Electron Transport Complex IV