Regulation of Aromatic Compound Degradation in Acinetobacter

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These studies focus on aromatic compound degradation by the soil bacterium Acinetobacter sp. strain ADP1. Catabolic pathways, which serve as model systems for understanding many aspects of biology, can be manipulated for bioremediation and for the generation of useful chemicals. The success of such ventures rests on a thorough understanding of microbial metabolic and genetic regulation. The first objective of this project is to determine the molecular basis for a recently discovered novel type of transcriptional activation. BenM, a transcriptional regulator involved in the degradation of benzoate by strain ADP1, was found to respond synergistically to two different metabolites. The synergistic modulation of transcriptional regulation in response to more than one inducer can significantly alter gene expression and may be a common biological regulatory feature. These studies will determine the specific nucleotide and amino acid sequences that control how BenM interacts with different effectors and DNA regions to regulate the expression of multiple genes and operons involved in aromatic compound catabolism. The second objective is to investigate preferential carbon source consumption by Acinetobacter strains when multiple growth substrates are available. Many soil bacteria degrade the components of a mixture of aromatic compounds in a sequential fashion. However, the method by which aromatic-compound degrading bacteria control the preferential consumption of carbon sources is unclear. In ADP1, regulation may occur at the transcriptional level, the post-transcriptional level, and/or at the level of substrate uptake into the cell. This research project will address how CatM and BenM repress genes needed for 4-hydroxybenzoate catabolism.