6533b837fe1ef96bd12a1e28

RESEARCH PRODUCT

Cloning, deletion, and characterization of PadR, the transcriptional repressor of the phenolic acid decarboxylase-encoding padA gene of Lactobacillus plantarum.

subject

description

ABSTRACTLactobacillus plantarumdisplays a substrate-induciblepadAgene encoding a phenolic acid decarboxylase enzyme (PadA) that is considered a specific chemical stress response to the inducing substrate. The putative regulator ofpadAwas located in thepadAlocus based on its 52% identity with PadR, thepadAgene transcriptional regulator ofPediococcus pentosaceus(L. Barthelmebs, B. Lecomte, C. Diviès, and J.-F. Cavin, J. Bacteriol.182:6724-6731, 2000). Deletion of theL. plantarum padRgene clearly demonstrates that the protein it encodes is the transcriptional repressor of divergently orientedpadA. ThepadRgene is cotranscribed with a downstream open reading frame (ORF1), the product of which may belong to a group of universal stress proteins (Usp). ThepadRdeletion mutant overexpressedpadAconstitutively, and thepadApromoter appears to be tightly regulated in this bacterium. Gel mobility shift assays using thepadAgene promoter region and purified PadR expressed inEscherichia coliindicated that operator DNA binding by PadR was not eliminated by addition ofp-coumarate. Gel mobility shift assays using partially purified extracts of native PadR protein from both phenolic acid-induced and noninducedL. plantarumcells demonstrate that inactivation of PadR by phenolic acids requires the integrity ofL. plantarumand mediation by a specific protein absent inE. coli.