title: Cys254 and Cys49/Cys87of simian virus 40 Vp1 are essential in formation of infectious virions.
abstract: The SV40 capsid is composed of pentameric capsomeres of Vp1. We have previously shown that disulfide linkages at Vp1 Cys9, Cys104, and Cys207 are essential in formation of infectious virions. Here, the role of the remaining four cysteines was explored. Single, double, and quadruple cys --> ser mutant genomes at Vp1 Cys49, Cys87, Cys254, and Cys267 codons were generated and transfected into CV-1 cells. The quadruple mutant Vp1 continued to localize to the nucleus and to bind DNA, but resulted in no plaques. SV40Vp1.Cys254 was the only single mutant with complete defect in plaque formation. The double mutant at Vp1.Cys49.Cys87 showed complete defect in plaque formation, while single mutants at the two residues resulted in plaques, suggesting a cumulative effect. All mutants defective in plaque formation continued to localize viral proteins in the nucleus. Taken together, our results suggest that Cys254 and the Cys49/Cys87 combination are essential in late stages of infectious virion formation.
authors.affiliation: Department of Biological Sciences, California State University, 1250 Bellflower Blvd., Long Beach, CA 90840-3702, USA. eghara@csulb.edu
authors.forename: Editte
authors.initials: E
authors.lastname: Gharakhanian
authors.forename: Wafa
authors.initials: W
authors.lastname: Mana
authors.forename: Manith
authors.initials: M
authors.lastname: Norng
mesh_terms: D000818:Animals; D000952:Antigens, Polyomavirus Transforming / Q000235:genetics / Q000378:metabolism; D036022:Capsid Proteins / Q000737:chemistry / Q000235:genetics* / Q000502:physiology*; D002460:Cell Line; D002467:Cell Nucleus / Q000821:virology; D002522:Chlorocebus aethiops; D003545:Cysteine / Q000737:chemistry; D016297:Mutagenesis, Site-Directed; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D013539:Simian virus 40 / Q000235:genetics* / Q000502:physiology*; D014162:Transfection; D010948:Viral Plaque Assay; D014771:Virion / Q000235:genetics / Q000502:physiology; D019065:Virus Assembly / Q000235:genetics / Q000502:physiology
chemical_list: D000952:Antigens, Polyomavirus Transforming; D036022:Capsid Proteins; D011993:Recombinant Fusion Proteins; C062481:VP1 protein, polyomavirus; D003545:Cysteine