title: Structural studies of recombinant Norwalk capsids.
abstract: Norwalk virus is the major cause of epidemic viral gastroenteritis in humans. Attempts to grow this human virus in laboratory cell lines have been unsuccessful; however, the Norwalk virus capsid protein, when expressed in insect cells infected with a recombinant baculovirus, spontaneously assembles into virus-like particles. The x-ray crystallographic structure of these recombinant Norwalk particles has been determined to 3.4 A, using a 22-A electron cryomicroscopy structure as a phasing model. The recombinant capsids, 380 A in diameter, exhibit a T=3 icosahedral symmetry. The capsid is formed by 90 dimers of the capsid protein, each of which forms an arch-like capsomere. The capsid protein has two distinct domains-a shell (S) and a protruding (P) domain-that are connected by a flexible hinge. Although the S domain has a classical beta-sandwich fold, the structure of the P domain is unlike any other viral protein. One of the subdomains in the P domain formed by the most variable part of the sequence is located at the exterior of the capsid.
authors.affiliation: Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA. vprasad@bcm.tmc.edu.
authors.forename: B V
authors.initials: BV
authors.lastname: Venkataram Prasad
authors.forename: M E
authors.initials: ME
authors.lastname: Hardy
authors.forename: M K
authors.initials: MK
authors.lastname: Estes
mesh_terms: D002213:Capsid / Q000737:chemistry*; D018360:Crystallography, X-Ray; D009663:Norwalk virus / Q000737:chemistry*; D011994:Recombinant Proteins / Q000737:chemistry
chemical_list: D011994:Recombinant Proteins