Formation of the Redox Cofactor Centers during Cox1 Maturation in Yeast Cytochrome Oxidase

Authors

Oleh Khalimonchuk, University of Nebraska-LincolnFollow
Megan Bestwick, University of Utah Health Sciences Center
Brigitte Meunier, CNRS, France
Talina C. Watts, University of Utah Health Sciences Center
Dennis R. Winge, University of Utah Health Sciences Center

Date of this Version

2010

Citation

MOLECULAR AND CELLULAR BIOLOGY, Feb. 2010, p. 1004–1017 Vol. 30, No. 4

Comments

Copyright © 2010, American Society for Microbiology. All Rights Reserved.

Abstract

The biogenesis of cytochrome c oxidase initiates with synthesis and maturation of the mitochondrionencoded Cox1 subunit prior to the addition of other subunits. Cox1 contains redox cofactors, including the low-spin heme a center and the heterobimetallic heme a₃:Cu_B center. We sought to identify the step in the maturation of Cox1 in which the redox cofactor centers are assembled. Newly synthesized Cox1 is incorporated within one early assembly intermediate containing Mss51 in Saccharomyces cerevisiae. Subsequent Cox1 maturation involves the progression to downstream assembly intermediates involving Coa1 and Shy1. We show that the two heme a cofactor sites in Cox1 form downstream of Mss51- and Coa1-containing Cox1 intermediates. These Cox1 intermediates form normally in cells defective in heme a biosynthesis or in cox1 mutant strains with heme a axial His mutations. In contrast, the Shy1-containing Cox1 assembly intermediate is perturbed in the absence of heme a. Heme a₃ center formation in Cox1 appears to be chaperoned by Shy1. Cu_B site formation occurs near or at the Shy1-containing Cox1 assembly intermediate also. The Cu_B metallochaperone Cox11 transiently interacts with Shy1 by coimmunoprecipitation. The Shy1-containing Cox1 complex is markedly attenuated in cells lacking Cox11 but is partially restored with a nonfunctional Cox11 mutant. Thus, formation of the heterobimetallic Cu_B:heme a₃ site likely occurs in the Shy1-containing Cox1 complex.