8GRA

Structure of Type VI secretion system cargo delivery vehicle Hcp-VgrG-PAAR

This is a non-PDB format compatible entry.

Summary for 8GRA

• Entry DOI: 10.2210/pdb8gra/pdb
• EMDB information: 34087
• Descriptor: Type VI secretion system spike protein Paar, Bacterodales T6SS protein TssD (Hcp), Type VI secretion system spike protein VgrG (3 entities in total)
• Functional Keywords: type vi secretion system, vgrg, hcp5, paar, transport protein
• Biological source: Bacteroides fragilis; More
• Total number of polymer chains: 12
• Total formula weight: 362114.95

Authors

Wen, Y.,He, W.,Zhu, L. (deposition date: 2022-09-01, release date: 2023-07-12, Last modification date: 2023-08-30)

Primary citation

He, W.,Wu, K.,Ouyang, Z.,Bai, Y.,Luo, W.,Wu, D.,An, H.,Guo, Y.,Jiao, M.,Qin, Q.,Zhang, J.,Wu, Y.,She, J.,Hwang, P.M.,Zheng, F.,Zhu, L.,Wen, Y.
Structure and assembly of type VI secretion system cargo delivery vehicle.
Cell Rep, 42:112781-112781, 2023

PubMed 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.

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

Experimental method

ELECTRON MICROSCOPY (2.8 Å)