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Publication Abstract from PubMed

Staphylococcus aureus pathogenicity islands (SaPIs) are molecular parasites that hijack helper phages for their transfer. SaPIbov5, the prototypical member of a family of cos type SaPIs, redirects the assembly of varphi12 helper capsids from prolate to isometric. This size and shape shift is dependent on the SaPIbov5-encoded protein Ccm, a homolog of the varphi12 capsid protein (CP). Using cryo-electron microscopy, we have determined structures of prolate varphi12 procapsids and isometric SaPIbov5 procapsids. varphi12 procapsids have icosahedral end caps with T(end) = 4 architecture and a T(mid) = 14 cylindrical midsection, whereas SaPIbov5 procapsids have T = 4 icosahedral architecture. We built atomic models for CP and Ccm, and show that Ccm occupies the pentameric capsomers in the isometric SaPIbov5 procapsids, suggesting that preferential incorporation of Ccm pentamers prevents the cylindrical midsection from forming. Our results highlight that pirate elements have evolved diverse mechanisms to suppress phage multiplication, including the acquisition of phage capsid protein homologs.

Shape shifter: redirection of prolate phage capsid assembly by staphylococcal pathogenicity islands.,Hawkins NC, Kizziah JL, Penades JR, Dokland T Nat Commun. 2021 Nov 4;12(1):6408. doi: 10.1038/s41467-021-26759-x. PMID:34737316^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.