|Frank C. Cannon
Professor of Biochemistry and Molecular Biology
Ph.D.: University College, Galway, Ireland
Genetic Regulators of Virulence Factors in Burkholderia cepacia
Burkholderia cepacia is an opportunistic pathogen capable of causing life-threatening necrotizing pneumonia in cystic fibrosis patients and in chronic granulomatous disease patients. Its ubiquitous nature, metabolic versatility, and resistance to many antibiotics in vivo makes B. cepacia a formidable pathogen. Its ability to colonize, multiply in vivo, evade various host defense systems, and produce damage to the host is dependent on a variety of virulence factors. These may include lipase, protease, hemolysin, siderophores, and exopolysaccharide, all of which we have shown to be produced by the strain used in our work.
We are interested in the coordinated regulation of these and other putative virulence factors. The success of a pathogen is dependent on its ability to coordinate the multifactorial and dynamic process of infection, and the elucidation of such genetic regulators is the goal of our research.
We have used the transposon TnphoA, which is a derivative of Tn5 with a truncated alkaline phosphatase gene, as an agent of mutagenesis. Using the suicide vector pRT733, we obtained a transposition frequency of >6 x 10(-6). Transconjugants show random single insertions as determined by hybridization studies of genomic DNA using a short 32P labeled phoA probe. A variety of mutants have been classified according to their deficiency in one or more of the putative virulence factors, and the phenotypes and genotypes of selected mutants are currently being examined.
Bosworth, H.A., Williams, M.K., Albrecht, K.A., Kwiatkowski, R., Beynon, J., Hankinson, T.R., Ronson, C.W., Cannon, F., Wacek, T.J. and Triplett, E.W. (1994) Alfalfa yield response to inoculation with recombinant strains of Rhizobium meliloti with an extra copy of dctABD and/or modified nifA expression. Appl. Envir. Microbial. 60, 3815-3832.
Buchanan-Wollaston, V., Snape, A. and Cannon, F. (1992) A plant selectable marker gene based on the detoxification of the herbicide dalapon. Plant Cell Reports 11, 627-631.
Liu, C.M., McLean, P.A., Sookdeo, C.C. and Cannon, F.C. (1991) Degradation of the herbicide glyphosate by members of the family Rhizobiaciae. Appl. Environ. Microbiol. 57, 1799-1804.
Cannon, M., Platz, J., O’Leary, M., Sookdeo, C. and Cannon, F. (1990) Organ specific modulation of gene expression in transgenic plants using antisense RNA. Plant Molec. Biol. 15, 39-47.
Hernandez, G., Cannon, F. and Cannon, M. (1989) The effect of presumptive polyadenylation signals on the expression of the CAT gene in transgenic tobacco. Plant Cell Reports 8, 195-198.