The mitochondrial protein import machinery. Role of ATP in dissociation of the Hsp70.Mim44 complex.
J Biol Chem
; 270(50): 29848-53, 1995 Dec 15.
Article
em En
| MEDLINE
| ID: mdl-8530381
ABSTRACT
Interaction of preproteins with the heat shock protein Hsp70 in the mitochondrial matrix is required for driving protein transport across the mitochondrial inner membrane. Binding of mt-Hsp70 to the protein Mim44 of the inner membrane import site seems to be an essential part of an ATP-dependent reaction cycle. However, the available results on the role played by ATP are controversial. Here we demonstrate that the mt-Hsp70.Mim44 complex contains ADP and that a nonhydrolyzable analog of ATP dissociates the mt-Hsp70.Mim44 complex in the presence of potassium ions. The previously reported requirement of ATP hydrolysis for complex dissociation was due to the use of a nonphysiological concentration of sodium ions. In the presence of potassium ions, mt-Hsp70 undergoes a conformational change that is not observed with a mutant Hsp70 defective in binding to Mim44. The mutant Hsp70 is able to bind substrate proteins, differentiating binding to Mim44 from binding to substrate proteins. We conclude that binding of ATP, not hydrolysis, is required to dissociate the mt-Hsp70.Mim44 complex and that the reaction cycle includes an ATP-induced conformational change of mt-Hsp70.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Saccharomyces cerevisiae
/
Proteínas de Transporte
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Trifosfato de Adenosina
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Proteínas de Choque Térmico HSP70
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Proteínas de Saccharomyces cerevisiae
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Proteínas de Transporte da Membrana Mitocondrial
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Proteínas de Membrana
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Mitocôndrias
Idioma:
En
Revista:
J Biol Chem
Ano de publicação:
1995
Tipo de documento:
Article
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