Affiliation:
1. University of Utah Health Sciences Center, Departments of Medicine and Biochemistry, Salt Lake City, Utah 84132
Abstract
ABSTRACT
Saccharomyces cerevisiae
cells lacking the cytochrome
c
oxidase (CcO) assembly factor Coa2 are impaired in Cox1 maturation and exhibit a rapid degradation of newly synthesized Cox1. The respiratory deficiency of
coa2
Δ cells is suppressed either by the presence of a mutant allele of the Cox10 farnesyl transferase involved in heme
a
biosynthesis or through impaired proteolysis by the disruption of the mitochondrial Oma1 protease. Cox10 with an N196K substitution functions as a robust gain-of-function suppressor of the respiratory deficiency of
coa2
Δ cells but lacks suppressor activity for two other CcO assembly mutant strains, the
coa1
Δ and
shy1
Δ mutants. The suppressor activity of N196K mutant Cox10 is dependent on its catalytic function and the presence of Cox15, the second enzyme involved in heme
a
biosynthesis. Varying the substitution at Asn196 reveals a correlation between the suppressor activity and the stabilization of the high-mass homo-oligomeric Cox10 complex. We postulate that the mutant Cox10 complex has enhanced efficiency in the addition of heme
a
to Cox1. Coa2 appears to impart stability to the oligomeric wild-type Cox10 complex involved in Cox1 hemylation.
Publisher
American Society for Microbiology
Subject
Cell Biology,Molecular Biology
Cited by
40 articles.
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