title: Molecular origins of synaptotagmin 1 activities on vesicle docking and fusion pore opening.
abstract: Synaptotagmin 1 (Syt1), a major Ca(2+) sensor in neuroexocytosis, utilizes SNARE- and membrane-binding to regulate vesicle fusion, a required process for neurotransmitter release at the synapse. However, the mechanism by which Syt1 orchestrates SNARE- and membrane- binding to control individual vesicle fusion steps is still unclear. In this study, we used a number of single vesicle assays that can differentiate intermediates of neuroexocytosis, to focus on Syt1 mutants that might impair Syt1-SNARE/PIP2 interaction, Ca(2+)-binding, or membrane penetration. Our results show that, although putative Syt1-SNARE/PIP2 coupling through the polybasic region of the C2B domain is critical for vesicle docking, its disruption does not affect content release. In contrast, Ca(2+)-binding and membrane-penetration mutants significantly reduce content release. Our results thus delineate multiple functions of Syt1 along the pathway of Ca(2+)-triggered exocytosis in unprecedented detail.
authors: Department of Biochemistry, Biophysics &Molecular Biology, Iowa State University, Ames, Iowa 50011, USA.
authors: Ying
authors: Y
authors: Lai
authors: Department of Biochemistry, Biophysics &Molecular Biology, Iowa State University, Ames, Iowa 50011, USA.
authors: Xiaochu
authors: X
authors: Lou
authors: Center for Mitochondrial Biology and Medicine, The Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology and Frontier Institute of Life Science, Frontier Institute of Science and Technology (FIST), Xi'an Jiaotong University, Xi'an 710049, P. R. China.
authors: Jiajie
authors: J
authors: Diao
authors: 1] Department of Biochemistry, Biophysics &Molecular Biology, Iowa State University, Ames, Iowa 50011, USA [2] Biomedical Research Institute, Korea Institute of Science and Technology (KIST), Hwarangno 14-gil 6, Seongbuk-gu, Seoul 136-791, South Korea.
authors: Yeon-Kyun
authors: YK
authors: Shin
mesh_terms: D002118:Calcium / Q000378:metabolism; D009154:Mutation; D011485:Protein Binding; D050600:SNARE Proteins / Q000378:metabolism; D050863:Synaptotagmin I / Q000235:genetics / Q000378:metabolism / Q000502:physiology*
chemical_list: D050600:SNARE Proteins; D050863:Synaptotagmin I; D002118:Calcium