Homologous Superfamily

Vgr protein, OB-fold domain superfamily (IPR037026)

Short name: Vgr_OB-fold_dom_sf

Overlapping entries


This domain occurs in a family of phage (and bacteriocin) proteins related to the phage P2 V gene product, which forms the small spike at the tip of the tail [PMID: 7483254]. Homologs in general are annotated as baseplate assembly protein V. At least one member is encoded within a region of Pectobacterium carotovorum (Erwinia carotovora) described as a bacteriocin, a phage tail-derived module able to kill bacteria closely related to the host strain.

It is also found in Vgr-related proteins. Genes encoding type VI secretion systems (T6SS) are widely distributed in pathogenic Gram-negative bacterial species. In Vibrio cholerae, T6SS have been found to secrete three related proteins extracellularly, VgrG-1, VgrG-2, and VgrG-3. VgrG-1 can covalently cross-link actin in vitro, and this activity was used to demonstrate that V. cholerae can translocate VgrG-1 into macrophages by a T6SS-dependent mechanism. VgrG-related proteins likely assemble into a trimeric complex that is analogous to that formed by the two trimeric proteins gp27 and gp5 that make up the baseplate "tail spike" of Escherichia coli bacteriophage T4. The VgrG components of the T6SS apparatus might assemble a "cell-puncturing device" analogous to phage tail spikes to deliver effector protein domains through membranes of target host cells [PMID: 17873062].

Gp5 is an integral component of the virion baseplate of bacteriophage T4. T4 Gp5 consists of 3 domains connected via long linkers: the N-terminal oligosaccharide/oligonucleotide-binding (OB)-fold domain, the middle lysozyme domain, and the C-terminal triplestranded-helix. The equivalent of the Gp5 OB-fold domain in the structure of VgrG is the domain of unknown function comprising residues 380-470 and conserved in all known VgrGs. This entry represents the OB-fold domain which consists of a 5-stranded antiparallel-barrel with a Greek-key topology [PMID: 19251641].

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.