Control of neurotransmitter release by two distinct membrane-binding faces of the Munc13-1 C(1)C(2)B region.
Control of neurotransmitter release by two distinct membrane-binding faces of the Munc13-1 C(1)C(2)B region.
复制标题
Munc13-1 C（1）C（2）B区域的两个不同的膜结合面对神经递质的控制释放。
DOI：
10.7554/elife.72030
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发表时间：
2021-11-15
期刊：
影响因子：
7.7
通讯作者：
Rosenmund C
中科院分区：
文献类型：
--
作者：
Camacho M;Quade B;Trimbuch T;Xu J;Sari L;Rizo J;Rosenmund C
Munc 13 -1通过其保守的C-末端区域在神经递质释放中起中心作用，所述C-末端区域包括二酰基甘油（DAG）结合C1结构域、Ca 2 +/PIP 2结合C2B结构域、MUN结构域和C2C结构域。提出Munc 13 -1通过C1 C2B区域与质膜的不同相互作用将突触囊泡桥接到质膜：（i）一个涉及预期产生Munc 13 -1的垂直取向并阻碍释放的多碱面;和（ii）另一个涉及预期导致倾斜取向并促进释放的DAG-Ca 2 +-PIP 2结合面。在这里，我们已经测试了这个模型，并研究了C1 C2B区域在神经递质释放中的作用。我们发现，K603 E或R769 E点突变的polybasic面对严重损害Ca 2 +-独立的脂质体桥接和融合在体外重建试验，和突触囊泡启动在原代小鼠海马培养。一个K720 E突变的多元面和一个K706 E突变的C2 B结构域钙结合环有较温和的影响，在重建试验中，不影响囊泡启动，但增强或削弱钙诱发的释放，分别。由这些突变组合引起的表型由K603 E和R769 E突变主导。我们的研究结果表明，Munc 13 -1的C1-C2B区域在囊泡启动中起着核心作用，并支持这一观点，即该区域的两个不同的面孔控制神经递质释放和短期突触前可塑性。
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.