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The cleaved presequence is not required for import of subunit 6 of the cytochrome bc 1 complex into yeast mitochondria or assembly into the complex*
Author(s) -
DeLabre Marie Laure,
Nett Jürgen H,
Trumpower Bernard L
Publication year - 1999
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(99)00415-9
Subject(s) - protein subunit , mitochondrion , biochemistry , amino acid , yeast , biology , saccharomyces cerevisiae , chemistry , gene
Subunit 6 of the yeast cytochrome bc 1 complex contains a 25 amino acid presequence that is not present in the mature form of the protein in the bc 1 complex. The presequence of subunit 6 is atypical of presequences responsible for targeting proteins to mitochondria. Whereas mitochondrial targeting sequences rarely contain acidic residues and typically contain basic residues that can potentially form an amphiphilic structure, the presequence of subunit 6 contains only one basic amino acid and is enriched in acidic amino acids. If the 25 amino acid presequence is deleted, subunit 6 is imported into mitochondria and assembled into the cytochrome bc 1 complex and the activity of the bc 1 complex is identical to that from a wild‐type yeast strain. However, if the C‐terminal 45 amino acids are truncated from the protein, subunit 6 is not present in the mitochondria and the activity of the bc 1 complex is diminished by half, identical to that of the bc 1 complex from a yeast strain in which the QCR6 gene is deleted. These results indicate that the presequence of subunit 6 is not required for targeting to mitochondria or assembly of the subunit into the bc 1 complex and that information necessary for targeting and import into mitochondria may be present in the C‐terminus of the protein.