7JW1

Satellite phage P4 procapsid including size determination (Sid) protein

Summary for 7JW1

• Entry DOI: 10.2210/pdb7jw1/pdb
• EMDB information: 22513
• Descriptor: Major capsid protein gpN, Size determination protein Sid (2 entities in total)
• Functional Keywords: bacteriophage, phage, procapsid, satellite phage, size determination, capsid protein, molecular piracy, virus
• Biological source: Escherichia phage P2; More
• Total number of polymer chains: 10
• Total formula weight: 376925.50

Authors

Kizziah, J.L.,Dokland, T. (deposition date: 2020-08-24, release date: 2020-09-16, Last modification date: 2024-10-30)

Primary citation

Kizziah, J.L.,Rodenburg, C.M.,Dokland, T.
Structure of the Capsid Size-Determining Scaffold of "Satellite" Bacteriophage P4.
Viruses, 12:-, 2020

PubMed Abstract: P4 is a mobile genetic element (MGE) that can exist as a plasmid or integrated into its host genome, but becomes packaged into phage particles by a helper bacteriophage, such as P2. P4 is the original example of what we have termed "molecular piracy", the process by which one MGE usurps the life cycle of another for its own propagation. The P2 helper provides most of the structural gene products for assembly of the P4 virion. However, when P4 is mobilized by P2, the resulting capsids are smaller than those normally formed by P2 alone. The P4-encoded protein responsible for this size change is called Sid, which forms an external scaffolding cage around the P4 procapsids. We have determined the high-resolution structure of P4 procapsids, allowing us to build an atomic model for Sid as well as the gpN capsid protein. Sixty copies of Sid form an intertwined dodecahedral cage around the = 4 procapsid, making contact with only one out of the four symmetrically non-equivalent copies of gpN. Our structure provides a basis for understanding the mutants in gpN that prevent small capsid formation, as well as the "super-sid" mutations that counteract the effect of the mutations, and suggests a model for capsid size redirection by Sid.

PubMed: 32867300
DOI: 10.3390/v12090953

Experimental method

ELECTRON MICROSCOPY (4.19 Å)