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Sequential analysis of trans-SNARE formation in intracellular membrane fusion.
Alpadi, Kannan; Kulkarni, Aditya; Comte, Veronique; Reinhardt, Monique; Schmidt, Andrea; Namjoshi, Sarita; Mayer, Andreas; Peters, Christopher.
Afiliação
  • Alpadi K; Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas, United States of America.
PLoS Biol ; 10(1): e1001243, 2012 Jan.
Article em En | MEDLINE | ID: mdl-22272185
SNARE complexes are required for membrane fusion in the endomembrane system. They contain coiled-coil bundles of four helices, three (Q(a), Q(b), and Q(c)) from target (t)-SNAREs and one (R) from the vesicular (v)-SNARE. NSF/Sec18 disrupts these cis-SNARE complexes, allowing reassembly of their subunits into trans-SNARE complexes and subsequent fusion. Studying these reactions in native yeast vacuoles, we found that NSF/Sec18 activates the vacuolar cis-SNARE complex by selectively displacing the vacuolar Q(a) SNARE, leaving behind a Q(bc)R subcomplex. This subcomplex serves as an acceptor for a Q(a) SNARE from the opposite membrane, leading to Q(a)-Q(bc)R trans-complexes. Activity tests of vacuoles with diagnostic distributions of inactivating mutations over the two fusion partners confirm that this distribution accounts for a major share of the fusion activity. The persistence of the Q(bc)R cis-complex and the formation of the Q(a)-Q(bc)R trans-complex are both sensitive to the Rab-GTPase inhibitor, GDI, and to mutations in the vacuolar tether complex, HOPS (HOmotypic fusion and vacuolar Protein Sorting complex). This suggests that the vacuolar Rab-GTPase, Ypt7, and HOPS restrict cis-SNARE disassembly and thereby bias trans-SNARE assembly into a preferred topology.
Assuntos

Texto completo: 1 Base de dados: MEDLINE Assunto principal: Saccharomyces cerevisiae / Proteínas de Saccharomyces cerevisiae / Proteínas SNARE / Membranas Intracelulares / Fusão de Membrana Tipo de estudo: Prognostic_studies Idioma: En Revista: PLoS Biol Assunto da revista: BIOLOGIA Ano de publicação: 2012 Tipo de documento: Article País de afiliação: Estados Unidos

Texto completo: 1 Base de dados: MEDLINE Assunto principal: Saccharomyces cerevisiae / Proteínas de Saccharomyces cerevisiae / Proteínas SNARE / Membranas Intracelulares / Fusão de Membrana Tipo de estudo: Prognostic_studies Idioma: En Revista: PLoS Biol Assunto da revista: BIOLOGIA Ano de publicação: 2012 Tipo de documento: Article País de afiliação: Estados Unidos