Research Description:
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The immense potential for microorganisms such as Pseudomonas to degrade
a variety of highly toxic hydrocarbons has become increasingly important as greater
amounts of these compounds are spewed out into the environment. This potential
depends not only upon the wealth of catabolic enzymes that these organisms possess,
but also upon their capacity for adaptive change. Such capacity is promoted by
their inherent patterns of genetic regulation that allow for the "coincidental
induction" of various metabolic pathways, which in turn allows the positive
selection for the introduction of novel patterns of biodegradation.
Microbial degradation of aromatic hydrocarbons, such as benzoate and its substituted
derivatives, occurs primarily through the b-ketoadipate pathway. Research interests
in this laboratory center around two different aspects of gene regulation within
this central pathway: the characterization of two of the regulatory genes involved
in the induction of both branches of the pathway, and the genetic manipulation
and rearrangement of these regulatory genes to provide some definition of mechanisms
involved in protein/DNA, protein/protein and protein/inducer interactions.
Two branches of the b-ketoadipate pathway are positively regulated by the
products of the pcaR and catR regulatory genes, respectively.
Preliminary investigations that have included cloning, DNA sequencing and mRNA
analyses, together with an inordinate variety of DNA binding studies, have shown
that, while these two reglatory proteins share a number of functional similarities,
they differ markedly in their evolutionary pedigrees, and thus provide significant
insight into the way in which the regulatory makeup of the pathway has developed.
Additional avenues of research, which are actively being pursued in the laboratory
are
(1) Regulation of ornithine utilization within P. aeruginosa and
(2) Biosorption of Uranium by pseudomonads.
For additional information on either of these topics, please feel free to browse
the Laboratory's home page.
Quantitative primer extension analysis of catB, showing how expression of
the catBCA transcript varies in different strains grown under a variety of physiological
conditions.
Recent Publications:
Buck, G. W., L. Jiang, Z. Guo and J. E. Houghton Pseudomonas putida Encodes a b-ketoadipate Specific Transport (PcaT) that is Expressed from Within a pcaFTBDC Operon. Manuscript submitted to Journal of Bacteriology
Sumner, E. R., A. Shanmuganathan, T. C. Sideri, S. A. Willetts, J. E. Houghton and S. V. Avery (2005) Oxidative Protein Damage Causes Chromium Toxicity in Yeast Microbiology. (Accepted for Publication)
Shanmuganathan, A., S.V. Avery, S.A Willetts and J.E. Houghton (2004)
Copper-induced Oxidative Stress in Saccharomyces cerevisiae Targets
Enzymes of the Glycolytic Pathway
FEBS Letters. 556: 253-2259.
Sumner, E. R., A. M.Avery, A Shanmugnathan, J. E. Houghton, R. A
Robbins, and S. V. Avery (2003)
Cell Cycle and Age-Dependent Activation of Sod1p Drives the Formation
of Stress Resistant Cell Subpopulations within Clonal Cultures.
Molecular Microbiology. 32: 253-264.
Herman, H. H., Weimin, L., Petrecca, Herman, T. M., Christopher Bates, C., Simmons, R. and J. E. Houghton. (2001) Centrifugal Bioreactors and their Application in Wastewater Remediation Remediation 11: 15 - 33.
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