title: Conserved features in papillomavirus and polyomavirus capsids.
abstract: Capsids of papilloma and polyoma viruses (papovavirus family) are composed of 72 pentameric capsomeres arranged on a skewed icosahedral lattice (triangulation number of seven, T = 7). Cottontail rabbit papillomavirus (CRPV) was reported previously to be a T = 7laevo (left-handed) structure, whereas human wart virus, simian virus 40, and murine polyomavirus were shown to be T = 7dextro (right-handed). The CRPV structure determined by cryoelectron microscopy and image reconstruction was similar to previously determined structures of bovine papillomavirus type 1 (BPV-1) and human papillomavirus type 1 (HPV-1). CRPV capsids were observed in closed (compact) and open (swollen) forms. Both forms have star-shaped capsomeres, as do BPV-1 and HPV-1, but the open CRPV capsids are approximately 2 nm larger in radius. The lattice hands of all papillomaviruses examined in this study were found to be T = 7dextro. In the region of maximum contact, papillomavirus capsomeres interact in a manner similar to that found in polyomaviruses. Although papilloma and polyoma viruses have differences in capsid size (approximately 60 versus approximately 50 nm), capsomere morphology (11 to 12 nm star-shaped versus 8 nm barrel-shaped), and intercapsomere interactions (slightly different contacts between capsomeres), papovavirus capsids have a conserved, 72-pentamer, T = 7dextro structure. These features are conserved despite significant differences in amino acid sequences of the major capsid proteins. The conserved features may be a consequence of stable contacts that occur within capsomeres and flexible links that form among capsomeres.
authors.affiliation: Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA.
authors.forename: D M
authors.initials: DM
authors.lastname: Belnap
authors.forename: N H
authors.initials: NH
authors.lastname: Olson
authors.forename: N M
authors.initials: NM
authors.lastname: Cladel
authors.forename: W W
authors.initials: WW
authors.lastname: Newcomb
authors.forename: J C
authors.initials: JC
authors.lastname: Brown
authors.forename: J W
authors.initials: JW
authors.lastname: Kreider
authors.forename: N D
authors.initials: ND
authors.lastname: Christensen
authors.forename: T S
authors.initials: TS
authors.lastname: Baker
mesh_terms: D000818:Animals; D000956:Antigens, Viral / Q000737:chemistry; D052688:Bovine papillomavirus 1 / Q000737:chemistry / Q000648:ultrastructure; D002213:Capsid / Q000737:chemistry / Q000648:ultrastructure*; D036022:Capsid Proteins; D012777:Cottontail rabbit papillomavirus / Q000737:chemistry / Q000648:ultrastructure; D006801:Humans; D027383:Papillomaviridae / Q000737:chemistry / Q000648:ultrastructure*; D011120:Polyomavirus / Q000737:chemistry / Q000648:ultrastructure*; D011817:Rabbits; D016415:Sequence Alignment; D013539:Simian virus 40 / Q000737:chemistry / Q000648:ultrastructure; D015678:Viral Structural Proteins / Q000737:chemistry
chemical_list: D000956:Antigens, Viral; D036022:Capsid Proteins; C085217:L1 protein, Bovine papillomavirus; C073505:L1 protein, cottontail rabbit papillomavirus; C085218:L2 protein, Bovine papillomavirus; C073507:L2 protein, cottontail rabbit papillomavirus; D015678:Viral Structural Proteins