Article abstract
Nature Structural & Molecular Biology 15, 707 - 713 (2008)
Published online: 15 June 2008 | doi:10.1038/nsmb.1446
Complexin and Ca2+ stimulate SNARE-mediated membrane fusion
Tae-Young Yoon1,2,4,5, Xiaobing Lu3,5, Jiajie Diao2,5, Soo-Min Lee3, Taekjip Ha1,2 & Yeon-Kyun Shin3
Abstract
Ca2+-triggered, synchronized synaptic vesicle fusion underlies interneuronal communication. Complexin is a major binding partner of the SNARE complex, the core fusion machinery at the presynapse. The physiological data on complexin, however, have been at odds with each other, making delineation of its molecular function difficult. Here we report direct observation of two-faceted functions of complexin using the single-vesicle fluorescence fusion assay and EPR. We show that complexin I has two opposing effects on trans-SNARE assembly: inhibition of SNARE complex formation and stabilization of assembled SNARE complexes. Of note, SNARE-mediated fusion is markedly stimulated by complexin, and it is further accelerated by two orders of magnitude in response to an externally applied Ca2+ wave. We suggest that SNARE complexes, complexins and phospholipids collectively form a complex substrate for Ca2+ and Ca2+-sensing fusion effectors in neurotransmitter release.
- Howard Hughes Medical Institute, University of Illinois at Urbana-Champaign, 1110 West Green Street, Urbana, Illinois 61801-3080, USA.
- Department of Physics, University of Illinois at Urbana-Champaign, 1110 West Green Street, Urbana, Illinois 61801-3080, USA.
- Department of Biochemistry, Biophysics, and Molecular Biology, Iowa State University, 4152 Molecular Biology Building, Ames, Iowa 50011, USA.
- Present address: Department of Physics and KAIST Institute for the BioCentury, KAIST, 373-1 Guseong-dong, Yuseong-gu, Daejeon 305-701, Korea.
- These authors contributed equally to this work.
Correspondence to: Taekjip Ha1,2 e-mail: tjha@uiuc.edu
Correspondence to: Yeon-Kyun Shin3 e-mail: colishin@iastate.edu
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