Structure and assembly of type VI secretion system cargo delivery vehicle

Wenbo He; Ke Wu; Zhenlin Ouyang; Yixin Bai; Wen Luo; Di Wu; Hao An; Yucheng Guo; Min Jiao; Qian Qin; Jiaxin Zhang; Yi Wu; Junjun She; Peter M Hwang; Fang Zheng; Li Zhu; Yurong Wen

doi:10.1016/j.celrep.2023.112781

Structure and assembly of type VI secretion system cargo delivery vehicle

Cell Rep. 2023 Jul 25;42(7):112781. doi: 10.1016/j.celrep.2023.112781. Epub 2023 Jul 7.

Authors

Wenbo He¹, Ke Wu², Zhenlin Ouyang¹, Yixin Bai¹, Wen Luo³, Di Wu², Hao An², Yucheng Guo⁴, Min Jiao¹, Qian Qin¹, Jiaxin Zhang⁴, Yi Wu⁴, Junjun She¹, Peter M Hwang⁵, Fang Zheng⁴, Li Zhu⁶, Yurong Wen⁷

Affiliations

¹ Center for Microbiome Research of Med-X Institute, Shaanxi Provincial Key Laboratory of Sepsis in Critical Care Medicine, The First Affiliated Hospital, Xi'an Jiaotong University, Xi'an 710061, China.
² Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou 730000, China.
³ Department of Oncology, The Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi, China.
⁴ The Key Laboratory of Environment and Genes Related to Disease of Ministry of Education Health Science Center, Xi'an Jiaotong University, Xi'an 710061, China.
⁵ Department of Biochemistry, Faculty of Medicine & Dentistry, Edmonton, AB T6G 2R3, Canada.
⁶ Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou 730000, China; Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Electron Microscopy Centre of Lanzhou University, Lanzhou University, Lanzhou 730000, China. Electronic address: zhuli@lzu.edu.cn.
⁷ Center for Microbiome Research of Med-X Institute, Shaanxi Provincial Key Laboratory of Sepsis in Critical Care Medicine, The First Affiliated Hospital, Xi'an Jiaotong University, Xi'an 710061, China; The Key Laboratory of Environment and Genes Related to Disease of Ministry of Education Health Science Center, Xi'an Jiaotong University, Xi'an 710061, China. Electronic address: yurong.wen@xjtu.edu.cn.

PMID: 37421630
DOI: 10.1016/j.celrep.2023.112781

Abstract

Type VI secretion system is widely used in Gram-negative bacteria for injecting toxic effectors into neighboring prokaryotic or eukaryotic cells. Various effectors can be loaded onto the T6SS delivery tube via its core components: Hcp, VgrG, or PAAR. Here, we report 2.8-Å resolution cryo-EM structure of intact T6SS Hcp5-VgrG-PAAR cargo delivery system and crystal structure of unbound Hcp5 from B. fragilis NCTC 9343. Loading of Hcp5 hexameric ring onto VgrG causes expansion of its inner cavity and external surface, explaining how structural changes could be propagated to regulate co-polymerization and surrounding contractile sheath. High-affinity binding between Hcp and VgrG causes entropically unfavorable structuring of long loops. Furthermore, interactions between VgrG trimer and Hcp hexamer are asymmetric, with three of the six Hcp monomers exhibiting a major loop flip. Our study provides insights into the assembly, loading, and firing of T6SS nanomachine that contributes to bacterial inter-species competition and host interactions.

Keywords: Bacteroides fragilis; CP: Microbiology; Cryo-EM; Hcp-VgrG-PAAR; Type VI secretion system; cargo delivery vehicle; conformational change.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Bacterial Proteins / metabolism
Type VI Secretion Systems* / metabolism

Substances

Type VI Secretion Systems
Bacterial Proteins