title: Cryo-EM structure of a bacteriophage T4 gp24 bypass mutant: the evolution of pentameric vertex proteins in icosahedral viruses.
abstract: Many large viral capsids require special pentameric proteins at their fivefold vertices. Nevertheless, deletion of the special vertex protein gene product 24 (gp24) in bacteriophage T4 can be compensated by mutations in the homologous major capsid protein gp23. The structure of such a mutant virus, determined by cryo-electron microscopy to 26 angstroms, shows that the gp24 pentamers are replaced by mutant major capsid protein (gp23) pentamers at the vertices, thus re-creating a viral capsid prior to the evolution of specialized major capsid proteins and vertex proteins. The mutant gp23* pentamer is structurally similar to the wild-type gp24* pentamer but the insertion domain is slightly more distant from the gp23* pentamer center. There are additional SOC molecules around the gp23* pentamers in the mutant virus that were not present around the gp24* pentamers in the wild-type virus.
authors.affiliation: Department of Biological Sciences, Purdue University, 915 W. State Street, West Lafayette, IN 47907-2054, USA.
authors.forename: Andrei
authors.initials: A
authors.lastname: Fokine
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Battisti
authors.forename: Victor A
authors.initials: VA
authors.lastname: Kostyuchenko
authors.forename: Lindsay W
authors.initials: LW
authors.lastname: Black
authors.forename: Michael G
authors.initials: MG
authors.lastname: Rossmann
mesh_terms: D005075:Biological Evolution; D002213:Capsid / Q000737:chemistry; D036022:Capsid Proteins / Q000737:chemistry* / Q000235:genetics*; D020285:Cryoelectron Microscopy / Q000379:methods*; D004926:Escherichia coli / Q000821:virology; D007091:Image Processing, Computer-Assisted; D008854:Microscopy, Electron; D009154:Mutation; D017422:Sequence Analysis, DNA; D019065:Virus Assembly
chemical_list: D036022:Capsid Proteins; C074187:gene 24 protein, Enterobacteria phage T4; C064517:gp23 protein, Bacteriophage T4