Structural Roles for the Juxtamembrane Linker Region and Transmembrane Region of Synaptobrevin 2 in Membrane Fusion

• Main Authors: Yaru Hu, Le Zhu, Cong Ma
• Format: Article
• Language: English
• Published: Frontiers Media S.A. 2021-01-01
• Series: Frontiers in Cell and Developmental Biology
• Subjects: synaptobrevin-2; SNARE complex assembly; membrane fusion; Munc18; Munc13
• Online Access: https://www.frontiersin.org/articles/10.3389/fcell.2020.609708/full

Formation of the trans-SNARE complex is believed to generate a force transfer to the membranes to promote membrane fusion, but the underlying mechanism remains elusive. In this study, we show that helix-breaking and/or length-increasing insertions in the juxtamembrane linker region of synaptobrevin-2 exert diverse effects on liposome fusion, in a manner dependent on the insertion position relative to the two conserved tryptophan residues (W89/W90). Helical extension of synaptobrevin-2 to W89/W90 is a prerequisite for initiating membrane merger. The transmembrane region of synaptobrevin-2 enables proper localization of W89/W90 at the membrane interface to gate force transfer. Besides, our data indicate that the SNARE regulatory components Munc18-1 and Munc13-1 impose liposome fusion strong demand on tight coupling between the SNARE motif and the transmembrane region of synaptobrevin-2.