In:
Genetics, Oxford University Press (OUP), Vol. 145, No. 4 ( 1997-04-01), p. 903-910
Kurzfassung:
Cytochrome c oxidase subunit II (Cox2p) of Saccharomyces cerevisiae is synthesized within mitochondria as a precursor, pre-Cox2p. The 15-amino acid leader peptide is processed after export to the intermembrane space. Leader peptides are relatively unusual in mitochondrially coded proteins: indeed mammalian Cox2p lacks a leader peptide. We generated two deletions in the S. cerevisiae COX2 gene, removing either the leader peptide (cox2-20) or the leader peptide and processing site (cox2-21) without altering either the promoter or the mRNA-specific translational activation site. When inserted into mtDNA, both deletions substantially reduced the steady-state levels of Cox2p and caused a tight nonrespiratory phenotype. A respiring pseudorevertant of the cox2-20 mutant was heteroplasmic for the original mutant mtDNA and a ρ–-mtDNA whose deletion fused the first 251 codons of the mitochondrial gene encoding cytochrome b to the cox2-20 sequence. The resulting fusion protein was processed to yield functional Cox2p. Thus, the presence of amino-terminal cytochrome b sequence bypassed the need for the pre-Cox2p leader peptide. We propose that the pre-Cox2p leader peptide contains a targeting signal necessary for membrane insertion, without which it remains in the matrix and is rapidly degraded.
Materialart:
Online-Ressource
ISSN:
1943-2631
DOI:
10.1093/genetics/145.4.903
Sprache:
Englisch
Verlag:
Oxford University Press (OUP)
Publikationsdatum:
1997
ZDB Id:
1477228-0
SSG:
12
