Structural insights into fusidic acid resistance and sensitivity in EF-G
Structural insights into fusidic acid resistance and sensitivity in EF-G
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DOI：
10.1016/j.jmb.2005.02.066
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发表时间：
2005-05-13
影响因子：
5.6
通讯作者：
Logan, DT
中科院分区：
文献类型：
--
作者：
Hansson, S;Singh, R;Logan, DT
福西地酸（FA）是一种类固醇抗生素，通常用于治疗革兰氏阳性细菌感染。它通过在易位后阻滞核糖体上的延伸因子G （EF-G）来抑制蛋白质合成。在EF-G结构域G、III和V之间的界面上发现了大量具有强FA抗性的突变。然而，关于这种突变如何影响结构的直接信息迄今为止还没有。本文研究了嗜热热菌EF-G、G16V和T84A两种突变体的晶体结构，这两种突变体在体外分别表现出FA超敏性和抗性。这些突变体对GTP的亲和力也分别高于野生型EF-G和低于野生型EF-G。突变在开关11环中引起显著的构象变化，而对关键残基Phe90的位置产生相反的影响，后者会发生较大的构象变化。这与先前研究中报道的Phe90在FA敏感性中的重要性有关。这些结构证实了结构域G/结构域III/结构域V接口作为FA结合位点的关键组成部分的重要性。这些突变还会引起“p环赖氨酸”Lys25环境的微妙变化。这使我们对翻译gtpase的所有结构中等效残基的构象进行了研究，结果表明EF-G和eEF2形成了一个独立的组，并表明Lys25在两组中的作用可能不同。(c) 2005 Elsevier Ltd版权所有。
Fusidic acid (FA) is a steroid antibiotic commonly used against Gram positive bacterial infections. It inhibits protein synthesis by stalling elongation factor G (EF-G) on the ribosome after translocation. A significant number of the mutations conferring strong FA resistance have been mapped at the interfaces between domains G, III and V of EF-G. However, direct information on how such mutations affect the structure has hitherto not been available. Here we present the crystal structures of two mutants of Thermus thermophilus EF-G, G16V and T84A, which exhibit FA hypersensitivity and resistance in vitro, respectively. These mutants also have higher and lower affinity for GTP respectively than wild-type EF-G. The mutations cause significant conformational changes in the switch 11 loop that have opposite effects on the position of a key residue, Phe90, which undergoes large conformational changes. This correlates with the importance of Phe90 in FA sensitivity reported in previous studies. These structures substantiate the importance of the domain G/domain III/domain V interfaces as a key component of the FA binding site. The mutations also cause subtle changes in the environment of the "P-loop lysine", Lys25. This led us to examine the conformation of the equivalent residue in all structures of translational GTPases, which revealed that EF-G and eEF2 form a group separate from the others and suggested that the role of Lys25 may be different in the two groups. (c) 2005 Elsevier Ltd. All rights reserved.