Genetic Analysis of the Assimilation of C^sub 5^-Dicarboxylic Acids in Pseudomonas aeruginosa PAO1

There is a wealth of information on the genetic regulation and biochemical properties of bacterial ...-dicarboxylate transport systems. In sharp contrast, there are far fewer studies describing the transport and assimilation of ...-dicarboxylates among bacteria. In an effort to better our understanding on this subject, we identified the structural and regulatory genes necessary for the utilization of α-ketoglutarate (α-KG) in Pseudomonas aeruginosa PAO1. The PA5530 gene, encoding a putative dicarboxylate transporter, was found to be essential for the growth of P. aeruginosa PAO1 on both α-KG and glutarate (another ...-dicarboxylate). Metabolite analysis confirmed that the PA5530 gene was necessary for the uptake of extracellular α-KG. Like other substrate-inducible transporter genes, expression of the PA5530 gene was induced by extracellular ...-dicarboxylates. It was later found that the expression of the PA5530 gene was driven solely by α -24/-12 promoter recognized by the alternative sigma factor RpoN. Surprisingly, the enhancer binding protein MifR, which is known to have an essential role in biofilm development, was required for the expression of the PA5530 gene. The MifR protein is homologous to other transcriptional regulators involved in dicarboxylate assimilation, suggesting that MifR might interact with RpoN to activate the expression of the PA5530 gene in response to extracellular ...-dicarboxylates, especially α-KG. The results of this study provide a framework for exploring the assimilation of α-KG in other pseudomonads. (ProQuest: ... denotes formulae/symbols omitted.)