Dataset Information

Structure of the small outer capsid protein, Soc: a clamp for stabilizing capsids of T4-like phages.

ABSTRACT: Many viruses need to stabilize their capsid structure against DNA pressure and for survival in hostile environments. The 9-kDa outer capsid protein (Soc) of bacteriophage T4, which stabilizes the virus, attaches to the capsid during the final stage of maturation. There are 870 Soc molecules that act as a "glue" between neighboring hexameric capsomers, forming a "cage" that stabilizes the T4 capsid against extremes of pH and temperature. Here we report a 1.9 A resolution crystal structure of Soc from the bacteriophage RB69, a close relative of T4. The RB69 crystal structure and a homology model of T4 Soc were fitted into the cryoelectron microscopy reconstruction of the T4 capsid. This established the region of Soc that interacts with the major capsid protein and suggested a mechanism, verified by extensive mutational and biochemical studies, for stabilization of the capsid in which the Soc trimers act as clamps between neighboring capsomers. The results demonstrate the factors involved in stabilizing not only the capsids of T4-like bacteriophages but also many other virus capsids.

SUBMITTER: Qin L

PROVIDER: S-EPMC2813359 | biostudies-literature | 2010 Jan

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Structure of the small outer capsid protein, Soc: a clamp for stabilizing capsids of T4-like phages.

Qin Li L Fokine Andrei A O'Donnell Erin E Rao Venigalla B VB Rossmann Michael G MG

Journal of molecular biology 20091014 4

Many viruses need to stabilize their capsid structure against DNA pressure and for survival in hostile environments. The 9-kDa outer capsid protein (Soc) of bacteriophage T4, which stabilizes the virus, attaches to the capsid during the final stage of maturation. There are 870 Soc molecules that act as a "glue" between neighboring hexameric capsomers, forming a "cage" that stabilizes the T4 capsid against extremes of pH and temperature. Here we report a 1.9 A resolution crystal structure of Soc ...[more]

PMID: 19835886

Similar Datasets

Project description:UnlabelledRelatively little is known about the phages that infect agriculturally important nitrogen-fixing rhizobial bacteria. Here we report the genome and cryo-electron microscopy structure of the Sinorhizobium meliloti-infecting T4 superfamily phage ΦM9. This phage and its close relative Rhizobium phage vB_RleM_P10VF define a new group of T4 superfamily phages. These phages are distinctly different from the recently characterized cyanophage-like S. meliloti phages of the ΦM12 group. Structurally, ΦM9 has a T=16 capsid formed from repeating units of an extended gp23-like subunit that assemble through interactions between one subunit and the adjacent E-loop insertion domain. Though genetically very distant from the cyanophages, the ΦM9 capsid closely resembles that of the T4 superfamily cyanophage Syn9. ΦM9 also has the same T=16 capsid architecture as the very distant phage SPO1 and the herpesviruses. Despite their overall lack of similarity at the genomic and structural levels, ΦM9 and S. meliloti phage ΦM12 have a small number of open reading frames in common that appear to encode structural proteins involved in interaction with the host and which may have been acquired by horizontal transfer. These proteins are predicted to encode tail baseplate proteins, tail fibers, tail fiber assembly proteins, and glycanases that cleave host exopolysaccharide.ImportanceDespite recent advances in the phylogenetic and structural characterization of bacteriophages, only a small number of phages of plant-symbiotic nitrogen-fixing soil bacteria have been studied at the molecular level. The effects of phage predation upon beneficial bacteria that promote plant growth remain poorly characterized. First steps in understanding these soil bacterium-phage dynamics are genetic, molecular, and structural characterizations of these groups of phages. The T4 superfamily phages are among the most complex phages; they have large genomes packaged within an icosahedral head and a long, contractile tail through which the DNA is delivered to host cells. This phylogenetic and structural study of S. meliloti-infecting T4 superfamily phage ΦM9 provides new insight into the diversity of this family. The comparison of structure-related genes in both ΦM9 and S. meliloti-infecting T4 superfamily phage ΦM12, which comes from a completely different lineage of these phages, allows the identification of host infection-related factors.

Dataset Information

Structure of the small outer capsid protein, Soc: a clamp for stabilizing capsids of T4-like phages.

Publications

Structure of the small outer capsid protein, Soc: a clamp for stabilizing capsids of T4-like phages.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets