The LYR Protein Mzm1 Functions in the Insertion of the Rieske Fe/S Protein in Yeast Mitochondria

Authors

Aaron Atkinson, University of Utah Health Sciences Center
Pamela Smith, University of Utah Health Sciences Center
Jennifer L. Fox, University of Utah Health Sciences Center
Tie-Shong Cui, University of Utah Health Sciences Center
Oleh Khalimonchuk, University of Nebraska-LincolnFollow
Dennis R. Winge, University of Utah Health Sciences Center

Document Type

Article

Date of this Version

2011

Citation

MOLECULAR AND CELLULAR BIOLOGY, Oct. 2011, p. 3988–3996 Vol. 31, No. 19

Comments

Copyright © 2011, American Society for Microbiology. All Rights Reserved.

Abstract

The assembly of the cytochrome bc1 complex in Saccharomyces cerevisiae is shown to be conditionally dependent on a novel factor, Mzm1. Cells lacking Mzm1 exhibit a modest bc₁ defect at 30°C, but the defect is exacerbated at elevated temperatures. Formation of bc₁ is stalled in mzm1 Δ cells at a late assembly intermediate lacking the Rieske iron-sulfur protein Rip1. Rip1 levels are markedly attenuated in mzm1 Δ cells at elevated temperatures. Respiratory growth can be restored in the mutant cells by the overexpression of the Rip1 subunit. Elevated levels of Mzm1 enhance the stabilization of Rip1 through physical interaction, suggesting that Mzm1 may be an important Rip1 chaperone especially under heat stress. Mzm1 may function primarily to stabilize Rip1 prior to inner membrane (IM) insertion or alternatively to aid in the presentation of Rip1 to the inner membrane translocation complex for extrusion of the folded domain containing the iron-sulfur center.