The macropinocytic pathway in Dictyostelium discoideum is organized linearly. After actin-driven internalization, fluid material passes sequentially from endosomes to lysosomes, where molecules are degraded and absorbed. Residual material is exocytosed via post-lysosomal compartments. Syntaxin 7 is a SNARE (soluble N-ethylmaleimide-sensitive fusion protein attachment protein receptor) protein that is present and active in D. discoideum endosomes [Bogdanovic, Bruckert, Morio and Satre (2000) J. Biol. Chem. 275, 36691—36697]. Here we report the identification of its main SNARE partners by co-immunoprecipitation and MS peptide sequencing. The syntaxin 7 complex contains two co-t-SNAREs [Vti1 (Vps10p tail interactor 1) and syntaxin 8] and a v-SNARE [VAMP7 (vesicle-associated membrane protein 7)] (where t-SNAREs are SNAREs of the target compartment and v-SNAREs are SNAREs present in donor vesicles). In endosomes and in vitro, syntaxin 7, Vti1 and syntaxin 8 form a complex that is able to bind VAMP7. Antibodies to syntaxin 8 and a soluble recombinant VAMP7 fragment both inhibit in vitro reconstituted D. discoideum endosome fusion. The lysosomal content of syntaxin 7, Vti1, syntaxin 8 and VAMP7 is low compared with that in endosomes, implying a highly active recycling or retention mechanism. A likely model is that VAMP7 is a v-SNARE present on vesicles carrying lysosomal enzymes, and that the syntaxin 7—Vti1—syntaxin 8 t-SNARE complex is associated with incoming endocytic material.
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November 2002
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Research Article|
November 15 2002
Syntaxin 7, syntaxin 8, Vti1 and VAMP7 (vesicle-associated membrane protein 7) form an active SNARE complex for early macropinocytic compartment fusion in Dictyostelium discoideum Available to Purchase
Aleksandra BOGDANOVIC;
Aleksandra BOGDANOVIC
∗Laboratoire de Biochimie et Biophysique des Systèmes Intégrés, Département de Réponse et Dynamique Cellulaires, CEA-Grenoble, 17 rue des Martyrs, 38054 Grenoble Cedex 9, France
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Nelly BENNETT;
Nelly BENNETT
∗Laboratoire de Biochimie et Biophysique des Systèmes Intégrés, Département de Réponse et Dynamique Cellulaires, CEA-Grenoble, 17 rue des Martyrs, 38054 Grenoble Cedex 9, France
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Sylvie KIEFFER;
Sylvie KIEFFER
†Laboratoire de Chimie des Protéines, Département de Réponse et Dynamique Cellulaires, CEA-Grenoble, 17 rue des Martyrs, 38054 Grenoble Cedex 9, France,
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Mathilde LOUWAGIE;
Mathilde LOUWAGIE
†Laboratoire de Chimie des Protéines, Département de Réponse et Dynamique Cellulaires, CEA-Grenoble, 17 rue des Martyrs, 38054 Grenoble Cedex 9, France,
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Takahiro MORIO;
Takahiro MORIO
‡Institute of Biological Sciences, Gene Experiment Centre, University of Tsukuba, 1-1-1 Ten-nodai, Tsukuba-shi, Ibaraki 305-8572, Japan
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Jérôme GARIN;
Jérôme GARIN
†Laboratoire de Chimie des Protéines, Département de Réponse et Dynamique Cellulaires, CEA-Grenoble, 17 rue des Martyrs, 38054 Grenoble Cedex 9, France,
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Michel SATRE;
Michel SATRE
∗Laboratoire de Biochimie et Biophysique des Systèmes Intégrés, Département de Réponse et Dynamique Cellulaires, CEA-Grenoble, 17 rue des Martyrs, 38054 Grenoble Cedex 9, France
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Franz BRUCKERT
Franz BRUCKERT
1
∗Laboratoire de Biochimie et Biophysique des Systèmes Intégrés, Département de Réponse et Dynamique Cellulaires, CEA-Grenoble, 17 rue des Martyrs, 38054 Grenoble Cedex 9, France
1To whom correspondence should be addressed (e-mail [email protected]).
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Publisher: Portland Press Ltd
Received:
May 29 2002
Revision Received:
August 02 2002
Accepted:
August 13 2002
Accepted Manuscript online:
August 13 2002
Online ISSN: 1470-8728
Print ISSN: 0264-6021
The Biochemical Society, London ©2002
2002
Biochem J (2002) 368 (1): 29–39.
Article history
Received:
May 29 2002
Revision Received:
August 02 2002
Accepted:
August 13 2002
Accepted Manuscript online:
August 13 2002
Citation
Aleksandra BOGDANOVIC, Nelly BENNETT, Sylvie KIEFFER, Mathilde LOUWAGIE, Takahiro MORIO, Jérôme GARIN, Michel SATRE, Franz BRUCKERT; Syntaxin 7, syntaxin 8, Vti1 and VAMP7 (vesicle-associated membrane protein 7) form an active SNARE complex for early macropinocytic compartment fusion in Dictyostelium discoideum. Biochem J 15 November 2002; 368 (1): 29–39. doi: https://doi.org/10.1042/bj20020845
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