Sequential Processing of a Mitochondrial Tandem Protein: Insights into Protein Import in Schizosaccharomyces pombe

Authors

• Oleh Khalimonchuk, University of Nebraska-LincolnFollow
• Martin Ott, Universität München
• Soledad Funes, Universität München
• Kai Ostermann, Technische Universität Dresden
• Gerhard Rödel, Technische Universität Dresden
• Johannes M. Herrmann, Universität München

Document Type

Article

Date of this Version

2006

Citation

EUKARYOTIC CELL, July 2006, p. 997–1006, Vol. 5, No. 7

Comments

Copyright © 2006, American Society for Microbiology. All Rights Reserved.

Abstract

The sequencing of the genome of Schizosaccharomyces pombe revealed the presence of a number of genes encoding tandem proteins, some of which are mitochondrial components. One of these proteins (pre-Rsm22- Cox11) consists of a fusion of Rsm22, a component of the mitochondrial ribosome, and Cox11, a factor required for copper insertion into cytochrome oxidase. Since in Saccharomyces cerevisiae, Cox11 is physically attached to the mitochondrial ribosome, it was suggested that the tandem organization of Rsm22-Cox11 is used to covalently tie the mitochondrial ribosome to Cox11 in S. pombe. We report here that pre-Rsm22-Cox11 is matured in two subsequent processing events. First, the mitochondrial presequence is removed. At a later stage of the import process, the Rsm22 and Cox11 domains are separated by cleavage of the mitochondrial processing peptidase at an internal processing site. In vivo data obtained using a tagged version of pre-Rsm22- Cox11 confirmed the proteolytic separation of Cox11 from the Rsm22 domain. Hence, the tandem organization of pre-Rsm22-Cox11 does not give rise to a persistent fusion protein but rather might be used to increase the import efficiency of Cox11 and/or to coordinate expression levels of Rsm22 and Cox11 in S. pombe.