Cryo-electron Microscopy Structure and Transport Mechanism of a Wall Teichoic Acid ABC Transporter
Cryo-electron Microscopy Structure and Transport Mechanism of a Wall Teichoic Acid ABC Transporter
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DOI：
10.1128/mbio.02749-19
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发表时间：
2020-03-01
期刊：
影响因子：
6.4
通讯作者：
Chen, Yuxing
中科院分区：
文献类型：
--
作者：
Chen, Li;Hou, Wen-Tao;Chen, Yuxing
壁磷壁酸（WTA）是革兰氏阳性菌的主要细胞壁组分，例如耐甲氧西林金黄色葡萄球菌（MRSA），其是人类致命临床感染的常见原因。因此，不可或缺的ABC转运蛋白TarGH将WTA从细胞质翻转到细胞外空间，成为抗MRSA药物的一个有希望的靶点。在这里，我们报告的3.9埃低温电子显微镜（cryo-EM）结构的50%的序列相同的同源物的TarGH从Alicy-clobacillus herbarius在一个ATP-免费和面向内的构象。结合活性测定的结构分析使我们能够清楚地解码抗MRSA抑制剂Targostatin的结合位点和抑制机制，该抑制剂靶向TarGH。此外，我们提出了一个“曲轴连杆”的机制，利用TarGH，它可以适用于类似的ABC转运蛋白，通过相对微妙的构象变化转位一个相当大的基板。这些发现为合理设计和优化抗MRSA的抗生素提供了结构基础。重要意义壁磷壁酸（WTA）是耐甲氧西林金黄色葡萄球菌（MRSA）细胞壁的主要成分，也是MRSA的致病因子。ABC转运蛋白TarGH对于将WTA前体从细胞质翻转到细胞外空间是必不可少的，因此使其成为抗MRSA药物的有前途的药物靶标。TarGH同源物的3.9埃cryo-EM结构有助于我们解码最近报道的抑制剂Targostatin的结合位点和抑制机制，并为合理设计和优化潜在抗生素提供了结构平台。此外，我们提出了一个“曲轴连杆”的机制来解释如何通过微妙的构象变化的II型出口商的大基板易位。这些发现推进了我们对抗MRSA药物设计和ABC转运蛋白的理解。
The wall teichoic acid (WTA) is a major cell wall component of Grampositive bacteria, such as methicillin-resistant Staphylococcus aureus (MRSA), a common cause of fatal clinical infections in humans. Thus, the indispensable ABC transporter TarGH, which flips WTA from cytoplasm to extracellular space, becomes a promising target of anti-MRSA drugs. Here, we report the 3.9-angstrom cryo-electron microscopy (cryo-EM) structure of a 50% sequence-identical homolog of TarGH from Alicy-clobacillus herbarius at an ATP-free and inward-facing conformation. Structural analysis combined with activity assays enables us to clearly decode the binding site and inhibitory mechanism of the anti-MRSA inhibitor Targocil, which targets TarGH. Moreover, we propose a "crankshaft conrod" mechanism utilized by TarGH, which can be applied to similar ABC transporters that translocate a rather big substrate through relatively subtle conformational changes. These findings provide a structural basis for the rational design and optimization of antibiotics against MRSA.IMPORTANCE The wall teichoic acid (WTA) is a major component of cell wall and a pathogenic factor in methicillin-resistant Staphylococcus aureus (MRSA). The ABC transporter TarGH is indispensable for flipping WTA precursor from cytoplasm to the extracellular space, thus making it a promising drug target for anti-MRSA agents. The 3.9-angstrom cryo-EM structure of a TarGH homolog helps us to decode the binding site and inhibitory mechanism of a recently reported inhibitor, Targocil, and provides a structural platform for rational design and optimization of potential antibiotics. Moreover, we propose a "crankshaft conrod" mechanism to explain how a big substrate is translocated through subtle conformational changes of type II exporters. These findings advance our understanding of anti-MRSA drug design and ABC transporters.