Cysteine-dependent ubiquitination of Pex18p is linked to cargo translocation across the peroxisomal membrane.
J Biol Chem
; 286(50): 43495-505, 2011 Dec 16.
Article
em En
| MEDLINE
| ID: mdl-22021076
ABSTRACT
The peroxisomal matrix protein import is facilitated by cycling receptor molecules that shuttle between the cytosol and the peroxisomal membrane. In the yeast Saccharomyces cerevisiae, the import of proteins harboring a peroxisomal targeting signal of type II (PTS2) is mediated by the receptor Pex7p and its co-receptor Pex18p. Here we demonstrate that Pex18p undergoes two kinds of ubiquitin modifications. One of these ubiquitination events depends on lysines 13 and 20 and forces rapid Pex18p turnover by proteasomal degradation. A cysteine residue near the extreme Pex18p amino-terminus is required for the second type of ubiquitination. It turned out that this cysteine residue at position 6 is essential for the function of Pex18p in peroxisomal protein import but does not contribute to receptor-cargo association and binding to the peroxisomal import apparatus. However, in contrast to the wild-type protein, cysteine 6-mutated Pex18p is arrested in a membrane-protected state, whereas Pex7p is accessible in a protease protection assay. This finding indicates that Pex18p export is linked to cargo translocation, which supports the idea of an export-driven import of proteins into peroxisomes.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Peroxissomos
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Cisteína
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Proteínas de Saccharomyces cerevisiae
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Ubiquitinação
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Membranas Intracelulares
Idioma:
En
Revista:
J Biol Chem
Ano de publicação:
2011
Tipo de documento:
Article
País de afiliação:
Alemanha
País de publicação:
EEUU
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ESTADOS UNIDOS
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ESTADOS UNIDOS DA AMERICA
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EUA
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UNITED STATES
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UNITED STATES OF AMERICA
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US
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USA