1975 - 1977Visiting Assistant Professor, Department of Biological Sciences,
1972 - 1975Postdoctoral Research Associate, Department of Biological Sciences,
Dr. Jack Johnson uses a variety of cellular and molecular biology methods to develop and test atomic resolution models of particle-related events in the virus life cycle; he also uses viruses as a paradigm for developing methods to determine atomic resolution models of cellular mega-structures.
We investigate model virus systems that provide insights for understanding assembly, maturation, entry, localization, and replication processes. Viruses infecting bacteria, insects, plants and the extreme thermophile sulfolobus are investigated. These viruses have genomes of ssRNA, and dsDNA. We employ a variety of physical methods to investigate structure-function relationships, including single crystal x-ray diffraction, static and time-resolved solution x-ray diffraction, electron cryo microscopy (cryoEM) and image reconstruction, mass spectrometry, structure-based computational analyses and methods associated with thermodynamic characterization of virus particles and their transitions. Biological methods employed include the genetic engineering of viral genes and their expression in E. coli, mammalian cells, insect cells and yeast and the characterization of these gene products by physical methods. Cytological studies of viral entry and infection employ fluorescence and electron microscopy and particles assembled in heterologus expression systems.