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Publication Abstract from PubMed

Staphylococcus aureus pathogenicity islands (SaPIs), such as SaPI1, exploit specific helper bacteriophages, like 80alpha, for their high frequency mobilization, a process termed 'molecular piracy'. SaPI1 redirects the helper's assembly pathway to form small capsids that can only accommodate the smaller SaPI1 genome, but not a complete phage genome. SaPI1 encodes two proteins, CpmA and CpmB, that are responsible for this size redirection. We have determined the structures of the 80alpha and SaPI1 procapsids to near-atomic resolution by cryo-electron microscopy, and show that CpmB competes with the 80alpha scaffolding protein (SP) for a binding site on the capsid protein (CP), and works by altering the angle between capsomers. We probed these interactions genetically and identified second-site suppressors of lethal mutations in SP. Our structures show, for the first time, the detailed interactions between SP and CP in a bacteriophage, providing unique insights into macromolecular assembly processes.

Competing scaffolding proteins determine capsid size during mobilization of Staphylococcus aureus pathogenicity islands.,Dearborn AD, Wall EA, Kizziah JL, Klenow L, Parker LK, Manning KA, Spilman MS, Spear JM, Christie GE, Dokland T Elife. 2017 Oct 6;6. pii: e30822. doi: 10.7554/eLife.30822. PMID:28984245^[1]

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