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首页> 外文期刊>Journal of Molecular Biology >The LcrG Tip Chaperone Protein of the Yersinia pestis Type III Secretion System Is Partially Folded
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The LcrG Tip Chaperone Protein of the Yersinia pestis Type III Secretion System Is Partially Folded

机译：鼠疫耶尔森氏菌III型分泌系统的LcrG提示伴侣蛋白被部分折叠。

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摘要

The type III secretion system (T3SS) is essential in the pathogenesis of Yersinia pestis, the causative agent of plague. A small protein, LcrG, functions as a chaperone to the tip protein LcrV, and the LcrG LcrV interaction is important in regulating protein secretion through the T3SS. The atomic structure of the LcrG family is currently unknown. However, because of its predicted helical propensity, many have suggested that the LcrG family forms a coiled-coil structure. Here, we show by NMR and CD spectroscopy that LcrG lacks a tertiary structure and it consists of three partially folded a-helices spanning residues 7-38, 41-46, and 58-73. NMR titrations of LcrG with LcrV show that the entire length of a truncated LcrG (residues 7-73) is involved in binding to LcrV. However, there is regional variation in how LcrG binds to LcrV. The C-terminal region of a truncated LcrG (residues 52-73) shows tight binding interaction with LcrV while the N-terminal region (residues 7-51) shows weaker interaction with LcrV. This suggests that there are at least two binding events when LcrG binds to LcrV. Biological assays and mutagenesis indicate that the C-terminal region of LcrG (residues 52-73) is important in blocking protein secretion through the T3SS. Our results reveal structural and mechanistic insights into the atomic conformation of LcrG and how it binds to LcrV. (C) 2015 Elsevier Ltd. All rights reserved.
机译：III型分泌系统（T3SS）在鼠疫耶尔森菌（鼠疫的致病因子）的发病机理中至关重要。小蛋白质LcrG充当了末端蛋白质LcrV的伴侣，LcrG LcrV相互作用在调节T3SS的蛋白质分泌中很重要。 LcrG家族的原子结构目前未知。但是，由于其预测的螺旋倾向，许多人建议LcrG家族形成卷曲螺旋结构。在这里，我们通过NMR和CD光谱显示LcrG缺乏三级结构，它由三个部分折叠的a螺旋组成，跨越残基7-38、41-46和58-73。 LcrG与LcrV的NMR滴定表明，截短的LcrG的全长（残基7-73）与LcrV结合。但是，LcrG与LcrV的结合方式存在区域差异。截短的LcrG的C末端区域（残基52-73）显示与LcrV的紧密结合相互作用，而N末端区域（残基7-51）显示与LcrV的相互作用较弱。这表明当LcrG与LcrV结合时至少有两个结合事件。生物学分析和诱变表明，LcrG的C末端区域（残基52-73）在阻断T3SS的蛋白质分泌中很重要。我们的结果揭示了对LcrG的原子构象及其与LcrV结合的结构和机理的见解。 （C）2015 Elsevier Ltd.保留所有权利。

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