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科学家以单分子分辨率定量次级转运
作者:小柯机器人 发布时间:2019/11/14 14:20:27

美国威尔康奈尔医学公司Scott C. Blanchard、哥伦比亚大学Jonathan A. Javitch和Matthias Quick研究组合作,在单分子分辨率下定量次级转运。这一研究成果11月13日在线发表在国际学术期刊《自然》上。

研究人员利用单周和多周转分辨率进行成像,通过对单个底物分子跨脂质双分子层的转运来量化单个MhsT转运蛋白的活性,MhsT是典型次级转运蛋白神经递质:钠转运蛋白家族的成员。研究表明MhsT仅在特定生理条件下才有活性,并且运输周期的限速步骤随被运输底物的性质而变化。这些发现与细胞外变构底物结合位点一致,该位点调节了限制转运机制的多个方面,包括转运的底物释放后转运蛋白返回细胞膜外的速率。

据了解,次级主动转运蛋白对许多生理过程至关重要的,其利用电化学离子梯度的能量来推动底物在细胞膜上的转运。缓慢的运输速度和整体方法的固有局限性阻碍了对其作用机理的研究。

附:英文原文

Title: Quantifying secondary transport at single-molecule resolution

Author: Gabriel A. Fitzgerald, Daniel S. Terry, Audrey L. Warren, Matthias Quick, Jonathan A. Javitch, Scott C. Blanchard

Issue&Volume: 2019-11-13

Abstract: Secondary active transporters, which are vital for a multitude of physiological processes, use the energy of electrochemical ion gradients to power substrate transport across cell membranes1,2. Efforts to investigate their mechanisms of action have been hampered by their slow transport rates and the inherent limitations of ensemble methods. Here we quantify the activity of individual MhsT transporters, which are representative of the neurotransmitter:sodium symporter family of secondary transporters3, by imaging the transport of individual substrate molecules across lipid bilayers at both single- and multi-turnover resolution. We show that MhsT is active only when physiologically oriented and that the rate-limiting step of the transport cycle varies with the nature of the transported substrate. These findings are consistent with an extracellular allosteric substrate-binding site that modulates the rate-limiting aspects of the transport mechanism4,5, including the rate at which the transporter returns to an outward-facing state after the transported substrate is released. Imaging of substrate transport by individual MhsT transporters, members of the neurotransmitter:sodium symporter family of secondary transporters, at single- and multi-turnover resolution reveals that the rate-limiting step varies with the identity of the transported substrate.

DOI: 10.1038/s41586-019-1747-5

Source:https://www.nature.com/articles/s41586-019-1747-5

期刊信息

Nature:《自然》,创刊于1869年。隶属于施普林格·自然出版集团,最新IF:43.07
官方网址:http://www.nature.com/
投稿链接:http://www.nature.com/authors/submit_manuscript.html