NDLI: Control of neurotransmitter release by two distinct membrane-binding faces of the Munc13-1 C1C2B region

Content Provider	Directory of Open Access Journals (DOAJ)
Author	Marcial Camacho Bradley Quade Thorsten Trimbuch Junjie Xu Levent Sari Josep Rizo Christian Rosenmund
Abstract	Munc13-1 plays a central role in neurotransmitter release through its conserved C-terminal region, which includes a diacyglycerol (DAG)-binding C1 domain, a Ca2+/PIP2-binding C2B domain, a MUN domain and a C2C domain. Munc13-1 was proposed to bridge synaptic vesicles to the plasma membrane through distinct interactions of the C1C2B region with the plasma membrane: (i) one involving a polybasic face that is expected to yield a perpendicular orientation of Munc13-1 and hinder release; and (ii) another involving the DAG-Ca2+-PIP2-binding face that is predicted to result in a slanted orientation and facilitate release. Here, we have tested this model and investigated the role of the C1C2B region in neurotransmitter release. We find that K603E or R769E point mutations in the polybasic face severely impair Ca2+-independent liposome bridging and fusion in in vitro reconstitution assays, and synaptic vesicle priming in primary murine hippocampal cultures. A K720E mutation in the polybasic face and a K706E mutation in the C2B domain Ca2+-binding loops have milder effects in reconstitution assays and do not affect vesicle priming, but enhance or impair Ca2+-evoked release, respectively. The phenotypes caused by combining these mutations are dominated by the K603E and R769E mutations. Our results show that the C1-C2B region of Munc13-1 plays a central role in vesicle priming and support the notion that two distinct faces of this region control neurotransmitter release and short-term presynaptic plasticity.
e-ISSN	2050084X
DOI	10.7554/eLife.72030
Journal	eLife
Volume Number	10
Language	English
Publisher	eLife Sciences Publications Ltd
Publisher Date	2021-01-01
Publisher Place	United Kingdom
Access Restriction	Open
Subject Keyword	Medicine Science Biology (general) Munc13 Neurotransmitter Release Synaptic Vesicle Fusion Presynaptic Plasticity
Content Type	Text
Resource Type	Article

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