title: The tripartite capsid gene of Salmonella phage Gifsy-2 yields a capsid assembly pathway engaging features from HK97 and lambda.
abstract: Phage Gifsy-2, a lambdoid phage infecting Salmonella, has an unusually large composite gene coding for its major capsid protein (mcp) at the C-terminal end, a ClpP-like protease at the N-terminus, and a approximately 200 residue central domain of unknown function but which may have a scaffolding role. This combination of functions on a single coding region is more extensive than those observed in other phages such as HK97 (scaffold-capsid fusion) and lambda (protease-scaffold fusion). To study the structural phenotype of the unique Gifsy-2 capsid gene, we have purified Gifsy-2 particles and visualized capsids and procapsids by cryoelectron microscopy, determining structures to resolutions up to 12A. The capsids have lambdoid T=7 geometry and are well modeled with the atomic structures of HK97 mcp and phage lambda gpD decoration protein. Thus, the unique Gifsy-2 capsid protein gene yields a capsid maturation pathway engaging features from both phages HK97 and lambda.
authors.affiliation: Laboratoire de Microscopie Electronique Structurale, Institut de Biologie Structurale J.-P. Ebel, UMR 5075, Université Joseph Fourier, CEA, CNRS, 38027 Grenoble, France.
authors.forename: Grégory
authors.initials: G
authors.lastname: Effantin
authors.forename: Nara
authors.initials: N
authors.lastname: Figueroa-Bossi
authors.forename: Guy
authors.initials: G
authors.lastname: Schoehn
authors.forename: Lionello
authors.initials: L
authors.lastname: Bossi
authors.forename: James F
authors.initials: JF
authors.lastname: Conway
mesh_terms: D002213:Capsid / Q000378:metabolism* / Q000648:ultrastructure*; D036022:Capsid Proteins / Q000235:genetics / Q000378:metabolism*; D020285:Cryoelectron Microscopy; D005814:Genes, Viral; D012483:Salmonella Phages / Q000235:genetics / Q000502:physiology* / Q000648:ultrastructure*; D019065:Virus Assembly
chemical_list: D036022:Capsid Proteins