InterPro: IPR012332 Phage P22 tailspike

The tailspike protein of Salmonella bacteriophage P22 is a viral adhesion protein that mediates attachment of the viral protein to host cell-surface lipopolysaccharide. The tailspike protein displays both receptor binding and destroying properties, inactivating the receptor by endoglycosidase activity. P22 tailspike is a homotrimer composed of 666 amino acid polypeptide chains. P22 tailspike consists of three main structural elements: the head-binding domain at the N terminus (IPR009093), the beta-helix in the centre of the protein, and the beta-prism and caudal fin at the C terminus [1]. The P22 tailspike protein contains similar structural elements to pectin lyase [2]. The binding of the disaccharide product occurs within a positively charged cleft formed by loops extending from the surface of the beta-helix structure. Amino acid residues responsible for recognition of the disaccharide, as well as potential catalytic residues, have been identified [3]. This entry represents the family of phage P22 tailspike proteins, and includes proteins that display a similar pectin-lyase-type beta-helix fold.