The ts16 mutation of vaccinia virus WR (R. C. Condit, A. Motyczka, and G. Spizz, Virology 128:429-443, 1983) has been mapped by marker rescue to the 17L open reading frame located within the genomic HindIII I DNA fragment. The 17 gene encodes a 423-amino-acid polypeptide. Thermolabile growth was attributed to an amino acid substitution, Pro-344→Leu, in the predicted 17 protein. A normal temporal pattern of viral protein synthesis was elicited in cells infected with ts16 at the nonpermissive temperature (40°C). Electron microscopy revealed a defect in virion assembly at 40°C. Morphogenesis was arrested at a stage subsequent to formation of spherical immature particles. Western immunoblot analysis with antiserum directed against the 17 polypeptide demonstrated an immunoreactive 47-kDa polypeptide accumulating during the late phase of synchronous vaccinia virus infection. Immunoblotting of extracts of wild-type virions showed that the 17 protein is encapsidated within the virus core. The 17 polypeptide displays amino acid sequence similarity to the type II DNA topoisomerase of Saccharomyces cerevisiae.
All Science Journal Classification (ASJC) codes
- Insect Science