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摘要 : 在这篇论文中,作者采用单分子荧光共振能量转移成像、X-射线晶体学和分子动态模拟方法来研究GltPh(来自古菌Pyrococcus horikoshii的一个天冬氨酸转运蛋白)和这种酶的一个双突变体形式(它对基质亲和力较低、但对基质转运速度较大)的动态。

在这篇论文中,作者采用单分子荧光共振能量转移成像、X-射线晶体学和分子动态模拟方法来研究GltPh(来自古菌Pyrococcus horikoshii的一个天冬氨酸转运蛋白)和这种酶的一个双突变体形式(它对基质亲和力较低、但对基质转运速度较大)的动态。




Transport domain unlocking sets the uptake rate of an aspartate transporter

Glutamate transporters terminate neurotransmission by clearing synaptically released glutamate from the extracellular space, allowing repeated rounds of signalling and preventing glutamate-mediated excitotoxicity. Crystallographic studies of a glutamate transporter homologue from the archaeon Pyrococcus horikoshii, GltPh, showed that distinct transport domains translocate substrates into the cytoplasm by moving across the membrane within a central trimerization scaffold. Here we report direct observations of these ‘elevator-like’ transport domain motions in the context of reconstituted proteoliposomes and physiological ion gradients using single-molecule fluorescence resonance energy transfer (smFRET) imaging. We show that GltPh bearing two mutations introduced to impart characteristics of the human transporter exhibits markedly increased transport domain dynamics, which parallels an increased rate of substrate transport, thereby establishing a direct temporal relationship between transport domain motion and substrate uptake. Crystallographic and computational investigations corroborated these findings by revealing that the ‘humanizing’ mutations favour structurally ‘unlocked’ intermediate states in the transport cycle exhibiting increased solvent occupancy at the interface between the transport domain and the trimeric scaffold.(doi:10.1038/nature14158) 

对应Nature杂志: 2015年02月05日Nature杂志精选

来源: Nature 浏览次数:125


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