A novel two-step mechanism for removal of a mitochondrial signal sequence involves the mAAA complex and the putative rhomboid protease Pcp1

Item Type:	Article
Title:	A novel two-step mechanism for removal of a mitochondrial signal sequence involves the mAAA complex and the putative rhomboid protease Pcp1
Creators Name:	Esser, K. and Tursun, B. and Ingenhoven, M. and Michaelis, G. and Pratje, E.
Abstract:	The yeast protein cytochrome c peroxidase (Ccp1) is nuclearly encoded and imported into the mitochondrial intermembrane space, where it is involved in degradation of reactive oxygen species. It is known, that Ccp1 is synthesised as a precursor with a N-terminal pre-sequence, that is proteolytically removed during transport of the protein. Here we present evidence for a new processing pathway, involving novel signal peptidase activities. The mAAA protease subunits Yta10 (Afg3) and Yta12 (Rca1) were identified both to be essential for the first processing step. In addition, the Pcp1 (Ygr101w) gene product was found to be required for the second processing step, yielding the mature Ccp1 protein. The newly identified Pcp1 protein belongs to the rhomboid-GlpG superfamily of putative intramembrane peptidases. Inactivation of the protease motifs in mAAA and Pcp1 blocks the respective steps of proteolysis. A model of coupled Ccp1 transport and N-terminal processing by the mAAA complex and Pcp1 is discussed. Similar processing mechanisms may exist, because the mAAA subunits and the newly identified Pcp1 protein belong to ubiquitous protein families.
Keywords:	Cytochrome C Peroxidase, Mitochondrial Protein Sorting, AAA Protease, PCP1 Gene, Rhomboid Family
Source:	Journal of Molecular Biology
ISSN:	0022-2836
Publisher:	Elsevier
Volume:	323
Number:	5
Page Range:	835-843
Date:	8 November 2002
Official Publication:	https://doi.org/10.1016/S0022-2836(02)01000-8
PubMed:	View item in PubMed

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