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Import Pathway of Nuclear‐Encoded Cytochrome c Oxidase Subunit 2 Using Yeast as a Model
Author(s) -
Qualmann S. R.,
Daley D. O.,
Whelan J.,
Pratje E.
Publication year - 2003
Publication title -
plant biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.871
H-Index - 87
eISSN - 1438-8677
pISSN - 1435-8603
DOI - 10.1055/s-2003-44781
Subject(s) - biology , inner membrane , inner mitochondrial membrane , mitochondrion , protein subunit , protein targeting , cytochrome c oxidase , biochemistry , translocase of the inner membrane , intermembrane space , saccharomyces cerevisiae , nuclear gene , electron transport complex iv , mitochondrial carrier , yeast , microbiology and biotechnology , membrane protein , gene , mitochondrial dna , bacterial outer membrane , mitochondrial membrane transport protein , membrane , escherichia coli
Subunit 2 of cytochrome c oxidase (Cox2) is a mitochondrial‐encoded protein in most organisms. In soybean Glycine max a second Cox2 gene was identified in the nucleus which is functional, whereas the mitochondrial‐encoded cox2 gene is silent. For import and sorting of the nuclear‐encoded soybean Cox2 protein ( Gm Cox2p) into mitochondria, the protein has acquired an N‐terminal extension of 136 amino acid residues that is cleaved off in three steps during import. To study the function and processing of the Gm Cox2p leader peptide, we used yeast as a model system. Using different leader peptide‐GFP constructs, we were able to show that the i 1 intermediate is generated in the mitochondrial matrix and the mature protein is generated in the inner membrane space. Mitochondrial processing peptidase (MPP) is involved in processing the first part of the leader peptide, processing of the last part is catalysed by the inner membrane peptidase (IMP). Oxa1p is necessary for insertion of the protein into the inner mitochondrial membrane. Gm Cox2p therefore utilises many of the same components as its mitochondrial‐encoded predecessor, for sorting and maturation, following its import into the mitochondria.