The nitrite transport protein NirC from Salmonella typhimurium is a nitrite/proton antiporter
The nitrite transport protein NirC from Salmonella typhimurium is a nitrite/proton antiporter
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DOI：
10.1016/j.bbamem.2012.02.004
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发表时间：
2012-05-01
影响因子：
3.4
通讯作者：
Michel, Hartmut
中科院分区：
文献类型：
--
作者：
Rycovska, Adriana;Hatahet, Lina;Michel, Hartmut
在厌氧生长的细菌中，亚硝酸盐的转运是由一个完整的膜蛋白的形式-亚硝酸盐转运蛋白家族，NirC，在鼠伤寒沙门氏菌中起着关键作用的细胞内毒力催化。我们提出了一个功能特性的S。鼠伤寒沙门氏菌亚硝酸盐转运蛋白StmNirC在天然膜囊泡以及纯化和重组到蛋白脂质体。使用电生理技术的基础上的固体支撑膜，我们显示亚硝酸盐诱导的负电荷易位到蛋白脂质体重建与纯化StmNirC。这些数据证明了StmNirC的产电性及其对亚硝酸盐的底物特异性。使用吖啶橙子作为pH指示剂，我们表明，StmNirC作为一个次要的主动转运蛋白的外翻膜囊泡上的Δ pH值的变化进行监测。它促进亚硝酸盐的低亲和力转运偶联到H+反向转运，在pH 6至8的范围内具有pH独立性。除亚硝酸盐外，硝酸盐也由StmNirC转运，但通量降低且完全不存在质子反向转运活性。综上所述，这些数据表明StmNirC的双特异性阴离子选择性具有离子特异性转运模式。这可能在生理条件下调节亚硝酸盐转运中发挥作用。(C)2012 Elsevier B. V.保留所有权利。
In anaerobically grown bacteria, transport of nitrite is catalyzed by an integral membrane protein of the form ate-nitrite transporter family, NirC, which in Salmonella typhimurium plays a critical role in intracellular virulence. We present a functional characterization of the S. typhimurium nitrite transporter StmNirC in native membrane vesicles as well as purified and reconstituted into proteoliposomes. Using an electrophysiological technique based on solid supported membranes, we show nitrite induced translocation of negative charges into proteoliposomes reconstituted with purified StmNirC. These data demonstrate the electrogenicity of StmNirC and its substrate specificity for nitrite. Monitoring changes in Delta pH on everted membrane vesicles containing overexpressed StmNirC using acridine orange as a pH indicator we demonstrate that StmNirC acts as a secondary active transporter. It promotes low affinity transport of nitrite coupled to H+ antiport with a pH independent profile in the pH range from 6 to 8. In addition to nitrite also nitrate is transported by StmNirC, but with reduced flux and complete absence of proton antiport activity. Taken together, these data suggest a bispecific anion selectivity of StmNirC with an ion specific transport mode. This may play a role in regulating nitrite transport under physiological conditions. (C) 2012 Elsevier B.V. All rights reserved.