%0 Journal Article %A Lundgren, Benjamin R. %A Harris, Joshua R. %A Sarwar, Zaara %A Scheel, Ryan A. %A Nomura, Christopher T. %T The metabolism of (R)-3-hydroxybutyrate is regulated by the enhancer-binding protein PA2005 and the alternative sigma factor RpoN in Pseudomonas aeruginosa PAO1 %D 2015 %J Microbiology, %V 161 %N 11 %P 2232-2242 %@ 1465-2080 %R https://doi.org/10.1099/mic.0.000163 %I Microbiology Society, %X A variety of soil-dwelling bacteria produce polyhydroxybutyrate (PHB), which serves as a source of energy and carbon under nutrient deprivation. Bacteria belonging to the genus Pseudomonas do not generally produce PHB but are capable of using the PHB degradation product (R)-3-hydroxybutyrate [(R)-3-HB] as a growth substrate. Essential to this utilization is the NAD+-dependent dehydrogenase BdhA that converts (R)-3-HB into acetoacetate, a molecule that readily enters central metabolism. Apart from the numerous studies that had focused on the biochemical characterization of BdhA, there was nothing known about the assimilation of (R)-3-HB in Pseudomonas, including the genetic regulation of bdhA expression. This study aimed to define the regulatory factors that govern or dictate the expression of the bdhA gene and (R)-3-HB assimilation in Pseudomonas aeruginosa PAO1. Importantly, expression of the bdhA gene was found to be specifically induced by (R)-3-HB in a manner dependent on the alternative sigma factor RpoN and the enhancer-binding protein PA2005.This mode of regulation was essential for the utilization of (R)-3-HB as a sole source of energy and carbon. However, non-induced levels of bdhA expression were sufficient for P. aeruginosa PAO1 to grow on ( ± )-1,3-butanediol, which is catabolized through an (R)-3-HB intermediate. Because this is, we believe, the first report of an enhancer-binding protein that responds to (R)-3-HB, PA2005 was named HbcR for (R)-3-hydroxybutyrate catabolism regulator. %U https://www.microbiologyresearch.org/content/journal/micro/10.1099/mic.0.000163