Karla A. Kirkegaard

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Karla A. Kirkegaard, Associate Professor Microbiology and Immunology; Fairchild Building D309A Stanford University School of Medicine, Stanford CA 94305-5124. Tel: (650) 498-7075. FAX: (650) 498-7147.
Email: karlak@leland.stanford.edu

For many subcellular viruses and parasites, RNA, not DNA, is the carrier of genetic information. This has several interesting consequences for the genetics and biology of these genomes. For poliovirus for example, the mechanism of genetic recombination is vastly different from the breaking-and-rejoining found in DNA genomes, occuring instead by template switching by the viral RNA-dependent RNA polymerase, 3D. For RNA genomes like that of poliovirus that propagate in the cytoplasm of infected eukaryotic host cells, the colocalization of genome replication and translation of proteins makes possible direct coupling of this process so that it is likely that several encoded proteins act predominately in cis. To make infected cells more habitable environments, many RNA viruses engineer drastic reorganizations of both nuclear and cytoplasmic compartments.

Our laboratory is taking the following approaches to investigate the cell biology, genetics and biochemistry of RNA viral propagation, using poliovirus as a model system:
(i) Based on the three-dimensional structure of the poliovirus polymerase determined in the laboratory of Steve Schultz (U. Colorado, Boulder), we are identifying amino acid residues and protein surfaces involved in binding RNA, other viral proteins and host cell proteins during RNA synthesis within infected cells.
(ii) Using both in vitro assays for viral growth and infections of tissue-culture cells with genetically engineered viruses, we are investigating the genetics of each of the viral coding regions and the mechanism of RNA recombination.
(iii) We are employing both in vitro assays for protein secretion and ultrastructural and biochemical analysis of cells that express individual poliovirus proteins to understand the mechanisms of cytoplasmic reorganization during viral infection. It is likely that viruses such as poliovirus exploit existing cellular mechanisms to construct structures useful to the virus during infection.

There is more information on the Kirkegaard Lab Home Page.
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