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Nature:SLAC1细菌同源物的晶体结构被确定

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摘要 : SLAC1是一个最近识别出的、存在于植物叶子中的阴离子通道,在那里它控制膨压(turgor pressure),从而控制植物气门响应包括二氧化碳、臭氧和干旱在内的环境因素而开启。现在,细菌身上相当于SLAC1的一种物质(即来自“流感嗜血杆菌”的“亚碲酸盐抗性蛋白TehA”)的X-射线晶体结构已被确定。由结构启发而获得的突变发生机理被用来分析该通道的导电性质。气孔的静电特性表明

SLAC1是一个最近识别出的、存在于植物叶子中的阴离子通道,在那里它控制膨压(turgor pressure),从而控制植物气门响应包括二氧化碳、臭氧和干旱在内的环境因素而开启。现在,细菌身上相当于SLAC1的一种物质(即来自“流感嗜血杆菌”的“亚碲酸盐抗性蛋白TehA”)的X-射线晶体结构已被确定。由结构启发而获得的突变发生机理被用来分析该通道的导电性质。气孔的静电特性表明,不同阴离子之间的选择性在很大程度上是离子脱水的能量成本的一个函数。

这项工作以及对该细菌蛋白功能所做的进一步研究表明,SLAC1 和TehA代表着由环境刺激控制的一大类选择性阴离子通道。

生物谷推荐英文摘要:

Nature doi:10.1038/nature09487

Homologue structure of the SLAC1 anion channel for closing stomata in leaves
Yu-hang Chen,Lei Hu,Marco Punta,Renato Bruni,Brandan Hillerich,Brian Kloss,Burkhard Rost,James Love,Steven A. Siegelbaum& Wayne A. Hendrickson

The plant SLAC1 anion channel controls turgor pressure in the aperture-defining guard cells of plant stomata, thereby regulating the exchange of water vapour and photosynthetic gases in response to environmental signals such as drought or high levels of carbon dioxide. Here we determine the crystal structure of a bacterial homologue (Haemophilus influenzae) of SLAC1 at 1.20 ? resolution, and use structure-inspired mutagenesis to analyse the conductance properties of SLAC1 channels. SLAC1 is a symmetrical trimer composed from quasi-symmetrical subunits, each having ten transmembrane helices arranged from helical hairpin pairs to form a central five-helix transmembrane pore that is gated by an extremely conserved phenylalanine residue. Conformational features indicate a mechanism for control of gating by kinase activation, and electrostatic features of the pore coupled with electrophysiological characteristics indicate that selectivity among different anions is largely a function of the energetic cost of ion dehydration.

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