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Bacteriophage P22 ejects all of its internal proteins before its genome

TitleBacteriophage P22 ejects all of its internal proteins before its genome
Publication TypeJournal Article
Year of Publication2015
AuthorsJin, Y, Sdao, SM, Dover, JA, Porcek, NB, Knobler, CM, Gelbart, WM, Parent, KN

Double-stranded DNA bacteriophages are highly pressurized, providing a force driving ejection of a significant fraction of the genome from its capsid. In P22-like Podoviridae, internal proteins (“E proteins”) are packaged into the capsid along with the genome, and without them the virus is not infectious. However, little is known about how and when these proteins come out of the virus. We employed an in vitro osmotic suppression system with high-molecular-weight polyethylene glycol to study P22 E protein release. While slow ejection of the DNA can be triggered by lipopolysaccharide (LPS), the rate is significantly enhanced by the membrane protein OmpA from Salmonella. In contrast, E proteins are not ejected unless both OmpA and LPS are present and their ejection when OmpA is present is largely complete before any genome is ejected, suggesting that E proteins play a key role in the early stage of transferring P22 DNA into the host.

LPS, lipopolysaccharide; PFU, plaque forming units; PEG, polyethylene glycol; dsDNA, double-stranded DNA; ssDNA, single-stranded DNA; OmpA, outer membrane protein A
Bacteriophage infectivity; Genome ejection; Internal protein ejection; Receptors; Osmotic suppression

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