Cryo-EM structures reveal the molecular mechanism of HflX-mediated erythromycin resistance in mycobacteria

IF 4.4 2区生物学 Q2 BIOCHEMISTRY & MOLECULAR BIOLOGY Structure Pub Date : 2024-07-18 DOI:10.1016/j.str.2024.06.016

引用次数: 0

Abstract

Mycobacterial HflX confers resistance against macrolide antibiotics. However, the exact molecular mechanism is poorly understood. To gain further insights, we determined the cryo-EM structures of M. smegmatis (Msm) HflX-50S subunit and 50S subunit-erythromycin (ERY) complexes at a global resolution of approximately 3 Å. A conserved nucleotide A2286 at the gate of nascent peptide exit tunnel (NPET) adopts a swayed conformation in HflX-50S complex and interacts with a loop within the linker helical (LH) domain of MsmHflX that contains an additional 9 residues insertion. Interestingly, the swaying of this nucleotide, which is usually found in the non-swayed conformation, is induced by erythromycin binding. Furthermore, we observed that erythromycin decreases HflX’s ribosome-dependent GTP hydrolysis, resulting in its enhanced binding and anti-association activity on the 50S subunit. Our findings reveal how mycobacterial HflX senses the presence of macrolides at the peptide tunnel entrance and confers antibiotic resistance in mycobacteria.

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低温电子显微镜结构揭示了分枝杆菌中 HflX 介导的红霉素抗药性的分子机制

分枝杆菌的 HflX 可产生对大环内酯类抗生素的耐药性。然而，人们对其确切的分子机制知之甚少。为了获得更深入的了解，我们以约 3 Å 的全局分辨率测定了 M. smegmatis（Msm）HflX-50S 亚基和 50S 亚基-红霉素（ERY）复合物的冷冻电镜结构。在 HflX-50S 复合物中，位于新生肽出口隧道（NPET）闸门处的一个保守核苷酸 A2286 采用了摇摆构象，并与 MsmHflX 连接器螺旋（LH）结构域中的一个环相互作用，该环含有额外的 9 个残基插入物。有趣的是，这种核苷酸的摇摆通常出现在非摇摆构象中，与红霉素结合后会诱发这种摇摆。此外，我们还观察到红霉素降低了 HflX 的核糖体依赖性 GTP 水解，从而增强了其在 50S 亚基上的结合和抗结合活性。我们的研究结果揭示了分枝杆菌 HflX 如何在肽隧道入口处感知大环内酯的存在，并赋予分枝杆菌抗生素耐药性。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Structure 生物-生化与分子生物学

CiteScore

8.90

自引率

1.80%

发文量

155

审稿时长

3-8 weeks

期刊介绍： Structure aims to publish papers of exceptional interest in the field of structural biology. The journal strives to be essential reading for structural biologists, as well as biologists and biochemists that are interested in macromolecular structure and function. Structure strongly encourages the submission of manuscripts that present structural and molecular insights into biological function and mechanism. Other reports that address fundamental questions in structural biology, such as structure-based examinations of protein evolution, folding, and/or design, will also be considered. We will consider the application of any method, experimental or computational, at high or low resolution, to conduct structural investigations, as long as the method is appropriate for the biological, functional, and mechanistic question(s) being addressed. Likewise, reports describing single-molecule analysis of biological mechanisms are welcome. In general, the editors encourage submission of experimental structural studies that are enriched by an analysis of structure-activity relationships and will not consider studies that solely report structural information unless the structure or analysis is of exceptional and broad interest. Studies reporting only homology models, de novo models, or molecular dynamics simulations are also discouraged unless the models are informed by or validated by novel experimental data; rationalization of a large body of existing experimental evidence and making testable predictions based on a model or simulation is often not considered sufficient.