9TIT

Baseplate arm (segment B) of phage 812 in the post-contraction state

Summary for 9TIT

• Entry DOI: 10.2210/pdb9tit/pdb
• EMDB information: 55969
• Descriptor: ORF64, ORF63, ORF65 (3 entities in total)
• Functional Keywords: phage, baseplate, virus
• Biological source: Staphylococcus phage 812K1/420; More
• Total number of polymer chains: 8
• Total formula weight: 581217.28

Authors

Binovsky, J.,Plevka, P. (deposition date: 2025-12-05, release date: 2026-05-20, Last modification date: 2026-07-08)

Primary citation

Binovsky, J.,Siborova, M.,Zlatohurska, M.,Novacek, J.,Bardy, P.,Baska, R.,Skubnik, K.,Botka, T.,Benesik, M.,Pantucek, R.,Tripsianes, K.,Plevka, P.
Conformational changes of the baseplate regulating tail contraction of Staphylococcus phage 812.
Embo J., 2026

PubMed Abstract: Phages with contractile tails employ elaborate mechanisms to penetrate bacterial cell walls and deliver their genomes into the host cytoplasm. Here, we used cryo-EM to show that the baseplate of phage 812, a member of the Kayvirus genus, which infects Gram-positive Staphylococcus strains, is formed of a core, wedge modules, and baseplate arms carrying receptor-binding proteins 1 and 2 and tripod complexes. Upon binding to a host cell, the receptor-binding proteins of phage 812 baseplate reorient and undergo conformational changes. The changes to the tripod complexes trigger the release of the central spike and weld proteins, which expose peptidoglycan-degrading domains of the hub proteins. Changes in the positions of baseplate arms are transmitted through wedge modules to tail sheath initiator proteins. The ring of the tail sheath initiator proteins expands and triggers the contraction of the tail sheath, which shortens to 50% and pushes the tail tube 10-30 nm into the bacterial cytoplasm. Homologous molecular mechanisms are probably shared by phages of the Herelleviridae family with contractile tails to infect Gram-positive bacteria.

PubMed: 42350675
DOI: 10.1038/s44318-026-00834-9

Experimental method

ELECTRON MICROSCOPY (4.4 Å)