This Pfam entry represents the Sulfolobus turreted icosahedral virus (STIV) penton protein second jelly roll domain. STIV is a virus that infects the archaeon Sulfolobus solfataricus and was isolated in acidic hot springs. The virus has a unique arch ...
This Pfam entry represents the Sulfolobus turreted icosahedral virus (STIV) penton protein second jelly roll domain. STIV is a virus that infects the archaeon Sulfolobus solfataricus and was isolated in acidic hot springs. The virus has a unique architecture based on a pseudo T = 31d capsid symmetry with each icosahedral asymmetric unit consisting of 15 copies of the coat subunit (B345), one copy of the A223 penton base protein, one copy of the C381 turret protein, and one copy of the A55 membrane protein. The pentameric penton base protein is a crucial component of the virus as it forms the vertices of the capsid shell and decorates the penton base structure forming the first floor of the turret. The penton protein contains three different layers, with the N termini forming a 10-stranded beta-pore, the middle layer comprising a canonical viral jelly-roll forming a pentameric ring, and the C-terminal forming a second pentameric ring of jelly-rolls. The virus shares the same coat subunit and penton base protein folds as some eukaryotic and bacterial viruses, suggesting that they derive from a common ancestor predating the divergence of the three kingdoms of life. The conservation of the A223 penton base jelly-roll fold, as well as the B345 double jelly-roll fold, strongly suggests an evolutionary connection for these protein modules among phages, archaeal viruses, and eukaryotic viruses.
