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Competing scaffolding proteins determine capsid size during mobilization of Staphylococcus aureus pathogenicity islands

Authors :
Erin A. Wall
James L. Kizziah
Laura Klenow
Michael S. Spilman
Terje Dokland
Altaira D. Dearborn
John M. Spear
Gail E. Christie
Laura K. Parker
Keith A. Manning
Source :
eLife, Vol 6 (2017), eLife
Publication Year :
2017
Publisher :
eLife Sciences Publications Ltd, 2017.

Abstract

Staphylococcus aureus pathogenicity islands (SaPIs), such as SaPI1, exploit specific helper bacteriophages, like 80α, 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 80α and SaPI1 procapsids to near-atomic resolution by cryo-electron microscopy, and show that CpmB competes with the 80α 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.

Details

Language :
English
Volume :
6
Database :
OpenAIRE
Journal :
eLife
Accession number :
edsair.doi.dedup.....40fb84e320e57c2e74ceafa7e5fa81aa