Research: Dr. James Champoux holds a B.S. in chemistry from the University of Washington and a Ph.D. in biochemistry from Stanford University. He did postdoctoral research at the Salk Institute on animal viruses, and did a sabbatical studying retroviruses at the Massachusetts Institute of Technology with Dr. David Baltimore. Dr. Champoux is the recipient of several awards including a Guggenheim Fellowship for sabbatical leave studies and the University of Washington's Distinguished Teaching Award. He was recently elected as a Fellow in the American Academy of Microbiology.
The research in Dr. Champoux's laboratory is focused on several projects relating to the enzymology of nucleic acid synthesis and repair. One project is concerned with human DNA topoisomerase I, an enzyme that provides swivels for DNA replication and other cellular processes such as transcription and recombination. Current studies on topoisomerase I are aimed at understanding (i) the structural basis for the preference for supercoiled over relaxed DNA, (ii) the mechanisms of catalysis and DNA relaxation, (iii) the interactions of topoisomerase I with other proteins in the nucleus, and (iv) the basis for the cytotoxicity of the anticancer drug, camptothecin. A second related interest is the enzyme, tyrosyl DNA phosphodiesterase (Tdp1), that is involved in the repair of irreversible topoisomerase I-DNA covalent adducts that occur under a variety of conditions in the cell, including exposure of cells to the anticancer drug camptothecin. Current work on Tdp1 focuses on the relationship between structure and function, and on the nature of the substrate in vivo.
A third project is concerned with the multiple roles of reverse transcriptase in retroviral replication. One aspect of this work focuses on how the DNA polymerase activity of reverse transcriptase carries out the process of displacement synthesis which is required for the production of the long terminal repeats on the ends of the viral DNA. Another interest is the RNase H activity of reverse transcriptase, which degrades the viral RNA after minus-strand synthesis and also produces the primer RNA for initiating plus-strand synthesis and removes RNA primers once they have been extended into DNA. The structural features of reverse transcriptase that are important for each of these reactions are being examined using both genetic and biochemical approaches. The long term goal of these studies is to understand the details of reverse transcription with an eye towards developing new anti-retroviral therapies. You can email Dr. Champoux at: champoux@u.washington.edu or visit his personal home page (http://faculty.washington.edu/champoux/). Selected Publications: Schultz, S. J., Zhang, M. and Champoux, J. J. (2003). Specific Cleavages by RNase H Facilitate Initiation of Plus-Strand RNA Synthesis by Moloney Murine Leukemia Virus. J. Virol. 77:5275-5285. Carey, J. F., Schultz, S. J., Sisson, L., Fazzio, T. G. and Champoux, J. J. (2003). DNA Relaxation by Human Topoisomerase I Occurs in the Closed Clamp Conformation of the Protein. Proc. Natl. Acad. Sci. USA. 100:5640-5645. Davies, D.R., Interthal, H., Champoux, J.J. and Hol, W.G.J. (2004). Explorations of Peptide and Oligonucleotide Binding Sites of Tyrosyl-DNA Phosphodiesterase (Tdp1) Using Vanadate Complexes. J. Med. Chem. 47:829-837. Winshell, J., Paulson, B.A., Buelow, B.D. and Champoux, J.J. (2004). Requirements for DNA Unpairing during Displacement Synthesis by HIV-1 Reverse Transcriptase. J. Biol. Chem. 279:52924-52933. Lanciault, C. and Champoux, J.J. (2005). Effects of Unpaired Nucleotides within HIV-1 Genomic Secondary Structures on Pausing and Strand Transfer. J. Biol. Chem. 280:2413-2423. Interthal, H., Chen, H. J., Kehl-Fie, T. E., Zotzmann, J., Leppard, J. B. and Champoux, J. J. (2005). SCAN1 Mutant Tdp1 Accumulates the Enzyme-DNA Intermediate and Causes Camptothecin Hypersensitivity. EMBO J. 24:2224-2233.
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