Open AccessElectron Transport in the cni ‐1 Mutant of Neurospora crassa
Author(s) -
EDWARDS David L.,
KLEIN Jerry L.,
WARDEN Joseph T.
Publication year - 1978
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1978.tb12257.x
Subject(s) - cytochrome c oxidase , cytochrome , neurospora crassa , mutant , cytochrome c1 , electron transport chain , biochemistry , cytochrome c , mitochondrion , cytochrome b , respiratory chain , alternative oxidase , cyanide , biology , heme , chemistry , coenzyme q – cytochrome c reductase , mitochondrial dna , enzyme , inorganic chemistry , gene
1 Mitochondria from the nuclear mutant cni ‐1 have no optically detectable cytochrome aa 3 in early log phase growth. These mitochondria have a high level of respiration that is not inhibited by cyanide but is inhibited by salicylhydroxamic acid. They also show a substantial amount of cyanide‐sensitive respiration. 2 As cultures of mutant cni ‐1 age, flux through the hydroxamate‐sensitive pathway decreases markedly while flux through the cytochrome chain remains constant. 3 Growth studies with mutant cni ‐1 indicate that the cytochrome chain in this mutant is more important in supporting growth than the hydroxamate‐sensitive pathway. 4 Measurements of the steady‐state level of reduction of cytochrome c in mutant cni ‐1 indicate that the rate‐limiting step in the cytochrome chain is at the position occupied by cytochrome oxidase. 5 Electron spin resonance studies with cni ‐1 mitochondria show normal cytochrome oxidase signals in the g ≅ 6 region although there is little or no optically detectable cytochrome aa 3 .