Sls1p stimulates Sec63p-mediated activation of Kar2p in a conformation-dependent manner in the yeast endoplasmic reticulum.
Mol Cell Biol
; 20(18): 6923-34, 2000 Sep.
Article
em En
| MEDLINE
| ID: mdl-10958688
ABSTRACT
We previously characterized the SLS1 gene in the yeast Yarrowia lipolytica and showed that it interacts physically with YlKar2p to promote translocation across the endoplasmic-reticulum membrane (A. Boisramé, M. Kabani, J. M. Beckerich, E. Hartmann, and C. Gaillardin, J. Biol. Chem. 27330903-30908, 1998). A Y. lipolytica Kar2p mutant was isolated that restored interaction with an Sls1p mutant, suggesting that the interaction with Sls1p could be nucleotide and/or conformation dependent. This result was used as a working hypothesis for more accurate investigations in Saccharomyces cerevisiae. We show by two-hybrid an in vitro assays that the S. cerevisiae homologue of Sls1p interacts with ScKar2p. Using dominant lethal mutants of ScKar2p, we were able to show that ScSls1p preferentially interacts with the ADP-bound conformation of the molecular chaperone. Synthetic lethality was observed between DeltaScsls1 and translocation-deficient kar2 or sec63-1 mutants, providing in vivo evidence for a role of ScSls1p in protein translocation. Synthetic lethality was also observed with ER-associated degradation and folding-deficient kar2 mutants, strongly suggesting that Sls1p functions are not restricted to the translocation process. We show that Sls1p stimulates in a dose-dependent manner the binding of ScKar2p on the lumenal J domain of Sec63p fused to glutathione S-transferase. Moreover, Sls1p is shown to promote the Sec63p-mediated activation of Kar2p's ATPase activity. Our data strongly suggest that Sls1p could be the first GrpE-like protein described in the endoplasmic reticulum.
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Base de dados:
MEDLINE
Assunto principal:
Proteínas de Membrana Transportadoras
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Saccharomyces cerevisiae
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Proteínas Fúngicas
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Proteínas de Transporte
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Proteínas de Choque Térmico HSP70
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Proteínas de Saccharomyces cerevisiae
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Retículo Endoplasmático
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Proteínas de Choque Térmico
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Proteínas de Membrana
Limite:
Animals
Idioma:
En
Ano de publicação:
2000
Tipo de documento:
Article