50S核糖体-HflX复合物的冷冻电镜结构揭示了大肠杆菌对PTC抗生素耐药的新机制

吴大木#,戴余浩#,马成英,高 宁*

50S核糖体-HflX复合物的冷冻电镜结构揭示了大肠杆菌对PTC抗生素耐药的新机制

吴大木#,戴余浩#,马成英,高 宁*

(北京大学1. 生命科学学院;2. 前沿交叉学科研究院;3.国家生物医学影像中心,北京100871)

   细菌HflX是一种保守的GTP酶,它与核糖体结合,参与应激条件下累积的停滞核糖体复合物的拆分。然而,50S核糖体-HflX复合物的高分辨率结构报道较少。本研究利用冷冻电镜技术解析了大肠杆菌(E. coli)50S核糖体亚基与HflX复合物的高分辨率结构。该结构揭示了HflX和核糖体RNA(rRNA)之间特异的相互作用,特别是HflX 的N端结构域的插入肽基转移酶中心(Peptidyl transferase center,PTC),并与PTC周围的残基间有直接的相互作用。HflX 的N端结构域内的一段loop(N-loop)与靶向于50S亚基PTC的抗生素,如氯霉素(Chloramphenicol,CHL)等的结合位点存在空间位阻。分子遗传学和生物化学的结果显示,删除hflX会导致细胞对氯霉素处理的高敏感性。本研究表明,HflX是一种细菌普遍的应激响应因子,可以介导PTC靶向抗生素的耐药。

关键词 HflX;抗生素抵抗;冷冻电镜

中图分类号:Q336;Q518.2;Q522+.3;Q939  文献标识码doi:10.3969/j.issn.1000-6281.2023.04.007

 

Cryo-EM structure of 50S-HflX complex reveals a new

mechanism of antibiotic resistance in E. coli

WU Da-mu1#, DAI Yu-hao 2#, MA Cheng-ying 2, GAO Ning 13 *

(1. School of Life Sciences, Peking University, Beijing 100871; 2. Academy of Advanced Interdisciplinary Studies, Peking University, Beijing 100871; 3. National Biomedical Imaging Center, Peking University, Beijing 100871, China)

Abstract  Bacterial HflX is a conserved ribosome-binding GTPase involved in splitting ribosomal complexes that are accumulated under stress condition. However, the atomic details of ribosomal interactions remain to be unclear. This study presents a high-resolution structure of E. coli 50S subunit bound with HflX. The structure reveals highly specific contacts between HflX and the ribosomal RNA. In particular, an insertion loop of the N-terminal domain of HflX situated in the peptidyl transferase center (PTC) makes direct interactions with PTC residues. Interestingly, this loop displays a steric clash with a few PTC-targeting antibiotics on the 50S subunit, such as chloramphenicol. Deletion of hflX results in the hypersensitivity to chloramphenicol treatment. Overall, these results suggest that HflX is a general stress-response factor that has a ubiquitous molecular function in PTC-bound antibiotic displacing.

Keywords  HflX; antibiotic resistance; Cryo-EM

 

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