Fei Li, Jacob Eriksen, Juan A. Oses-Prieto, Yessica K. Gomez, Hongfei Xu, Surabhi Hareendranath, Poulomi Das, Janet Finer-Moore, Phuong Nguyen, Alisa Bowen, Andrew Nelson, Alma Burlingame, Michael Grabe, Robert M. Stroud, Robert H. Edwards
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引用次数: 0
Abstract
The concentration of neurotransmitters inside synaptic vesicles (SVs) underlies the quantal nature of synaptic transmission. Uptake of glutamate, the principal excitatory neurotransmitter, is driven by membrane potential. To prevent nonquantal efflux of glutamate after SV exocytosis, the vesicular glutamate transporters (VGLUTs) are allosterically inhibited by the neutral pH of the synaptic cleft. To elucidate the mechanism, we determined high-resolution structures of rat VGLUT2 with a cyclic analog of glutamate. We propose a mechanism of substrate recognition in which a positively charged cytoplasmic vestibule electrostatically attracts the negatively charged substrate. We also identify modification of VGLUT2 by palmitoylation and find that this promotes retrieval of the transporter after exocytosis. The structure also reveals an extensive network of electrostatic interactions that forms the cytoplasmic gate. Functional analysis of a mutant that disrupts the network shows how this cytoplasmic gate confers the allosteric requirement for lumenal H+ required to restrict VGLUT activity to SVs. Guided by a structure of VGLUT2 with substrate, Li et al. identify the mechanisms for selective substrate recognition, a role for lipid modification in limiting axonal dispersion and for the cytoplasmic gate in allosteric regulation by lumenal H+.
期刊介绍:
Nature Structural & Molecular Biology is a comprehensive platform that combines structural and molecular research. Our journal focuses on exploring the functional and mechanistic aspects of biological processes, emphasizing how molecular components collaborate to achieve a particular function. While structural data can shed light on these insights, our publication does not require them as a prerequisite.