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首页> 外文期刊>Proceedings of the National Academy of Sciences of the United States of America >Structural and functional characterization of the nitrite channel NirC from Salmonella typhimurium
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Structural and functional characterization of the nitrite channel NirC from Salmonella typhimurium

机译：鼠伤寒沙门氏菌亚硝酸盐通道NirC的结构和功能表征

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摘要

Nitrite (NO_2~-) is a central intermediate in the nitrogen metabolism of microorganisms and plants, and is used as a cytotoxin by macro-phages as part of the innate immune response. The bacterial membrane protein NirC acts as a specific channel to facilitate the transport of nitrite anions across lipid bilayers for cytoplasmic detoxification. Despite NirC's importance in nitrogen metabolism and in the pathogenicity of enteric bacteria, available biochemical data are scarce. Here we present a functional and structural characterization of NirC from Salmonella typhimurium by lipid bilayer elec-trophysiology and X-ray crystallography. NirC is a pentameric member of the formateitrite transporter family of membrane proteins that operates as a channel with high conductance. Single-channel measurements reveal fast and slow gating events but, in contrast to the related FocA formate channel, no pH-dependent gating. A 2.4A crystal structure of NirC at pH 5 shows similarity to FocA and aquaporins, but lacks the structural asymmetry observed in the formate channel at similarly low pH. Resolved water molecules in the protomers suggest a transport mechanism that also permits a facultative NO_2~-/H~+ symport.
机译：亚硝酸盐（NO_2〜-）是微生物和植物氮代谢的主要中间产物，被巨噬细胞用作细胞毒素，作为先天免疫反应的一部分。细菌膜蛋白NirC充当特定通道，促进亚硝酸根阴离子跨脂质双层转运，以进行细胞质排毒。尽管NirC在氮代谢和肠道细菌的致病性方面很重要，但可用的生化数据却很少。在这里，我们通过脂双层电生理学和X射线晶体学介绍鼠伤寒沙门氏菌NirC的功能和结构表征。 NirC是膜蛋白的甲酸/亚硝酸盐转运蛋白家族的五聚体成员，可作为具有高电导率的通道运行。单通道测量揭示了快速和缓慢的门控事件，但是与相关的FocA甲酸盐通道相反，没有pH依赖性门控。 NirC在pH 5时的2.4A晶体结构显示出与FocA和水通道蛋白的相似性，但缺乏在相似的低pH下在甲酸盐通道中观察到的结构不对称性。在启动子中解析出的水分子表明了一种运输机制，该机制也允许兼性的NO_2〜-/ H〜+共存。

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    Wei Lue; Nikola J. Schwarzer; Juan Du; Elke Gerbig-Smentek; Susana L. A. Andrade; Oliver Einsle;

  • 作者单位

    Lehrstuhl fuer Biochemie, Institut fuer organische Chemie und Biochemie and BIOSS Centre for Biological Signalling Studies, Albert-Ludwigs-Universitaet Freiburg, 79104 Freiburg, Germany;

    Lehrstuhl fuer Biochemie, Institut fuer organische Chemie und Biochemie and BIOSS Centre for Biological Signalling Studies, Albert-Ludwigs-Universitaet Freiburg, 79104 Freiburg, Germany;

    Lehrstuhl fuer Biochemie, Institut fuer organische Chemie und Biochemie and BIOSS Centre for Biological Signalling Studies, Albert-Ludwigs-Universitaet Freiburg, 79104 Freiburg, Germany;

    Lehrstuhl fuer Biochemie, Institut fuer organische Chemie und Biochemie and BIOSS Centre for Biological Signalling Studies, Albert-Ludwigs-Universitaet Freiburg, 79104 Freiburg, Germany;

    Lehrstuhl fuer Biochemie, Institut fuer organische Chemie und Biochemie and BIOSS Centre for Biological Signalling Studies, Albert-Ludwigs-Universitaet Freiburg, 79104 Freiburg, Germany;

    Lehrstuhl fuer Biochemie, Institut fuer organische Chemie und Biochemie and BIOSS Centre for Biological Signalling Studies, Albert-Ludwigs-Universitaet Freiburg, 79104 Freiburg, Germany;

  • 收录信息 美国《科学引文索引》(SCI);美国《生物学医学文摘》(MEDLINE);美国《化学文摘》(CA);
  • 原文格式 PDF
  • 正文语种 eng
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  • 关键词

    ion channels; protein crystallography; planar lipid bilayer;

    机译：离子通道蛋白质晶体学平面脂质双层;

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