Vesicle capture by membrane-bound Munc13-1 requires self-assembly into discrete clusters

FEBS Letters

article

Feng Li¹  Ramalingam Venkat Kalyana Sundaram¹  Alberto T. Gatta¹  Jeff Coleman¹  Sathish Ramakrishnan¹  Shyam S. Krishnakumar¹  Frederic Pincet¹  James E. Rothman¹ 

[1] Department of Cell Biology, School of Medicine, Yale University;Nanobiology Institute, Yale School of Medicine;Laboratoire de Physique de l’Ecole normale supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université de Paris

关键词: cluster;    membrane fusion;    Munc13-1;    neurotransmission;    SNARE;    synaptic vesicle;   

DOI  :  10.1002/1873-3468.14157

来源: John Wiley & Sons Ltd.

【 摘 要 】

Munc13-1 is a large banana-shaped soluble protein that is involved in the regulation of synaptic vesicle docking and fusion. Recent studies suggest that multiple copies of Munc13-1 form nano-assemblies in active zones of neurons. However, it is not known whether such clustering of Munc13-1 is correlated with multivalent binding to synaptic vesicles or specific plasma membrane domains at docking sites in the active zone. The functional significance of putative Munc13-1 clustering is also unknown. Here, we report that nano-clustering is an inherent property of Munc13-1 and is indeed required for vesicle binding to bilayers containing Munc13-1. Purified Munc13-1 protein reconstituted onto supported lipid bilayers assembled into clusters containing from 2 to ˜ 20 copies as revealed by a combination of quantitative TIRF microscopy and step-wise photobleaching. Surprisingly, only clusters containing a minimum of 6 copies of Munc13-1 were capable of efficiently capturing and retaining small unilamellar vesicles. The C-terminal C 2 C domain of Munc13-1 is not required for Munc13-1 clustering, but is required for efficient vesicle capture. This capture is largely due to a combination of electrostatic and hydrophobic interactions between the C 2 C domain and the vesicle membrane.

【 授权许可】

Unknown