title: Structure/function analysis of the Pantoea stewartii quorum-sensing regulator EsaR as an activator of transcription.
abstract: In Pantoea stewartii subsp. stewartii, two regulatory proteins are key to the process of cell-cell communication known as quorum sensing: the LuxI and LuxR homologues EsaI and EsaR. Most LuxR homologues function as activators of transcription in the presence of their cognate acylated homoserine lactone (AHL) signal. However, EsaR was initially found to function as a repressor in the absence of AHL. Previous studies demonstrated that, in the absence of AHL, EsaR retains the ability to function as a weak activator of the lux operon in recombinant Escherichia coli. Here it is shown that both the N-terminal and the C-terminal domains of EsaR are necessary for positive regulation. A site-directed mutagenesis study, guided by homology modeling to LuxR and TraR, has revealed three critical residues in EsaR that are involved in activation of RNA polymerase. In addition, a native EsaR-activated promoter has been identified, which controls expression of a putative regulatory sRNA in P. stewartii.
authors.affiliation: Department of Biological Sciences, Virginia Tech, Blacksburg, Virginia 24061, USA.
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Schu
authors.forename: Aurelien L
authors.initials: AL
authors.lastname: Carlier
authors.forename: Katherine P
authors.initials: KP
authors.lastname: Jamison
authors.forename: Susanne
authors.initials: S
authors.lastname: von Bodman
authors.forename: Ann M
authors.initials: AM
authors.lastname: Stevens
mesh_terms: D054742:Acyl-Butyrolactones / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism*; D004252:DNA Mutational Analysis; D012321:DNA-Directed RNA Polymerases / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics / Q000502:physiology; D015964:Gene Expression Regulation, Bacterial; D016297:Mutagenesis, Site-Directed; D020636:Pantoea / Q000502:physiology*; D011401:Promoter Regions, Genetic; D017434:Protein Structure, Tertiary; D053038:Quorum Sensing; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism*; D014158:Transcription, Genetic
chemical_list: D054742:Acyl-Butyrolactones; D001426:Bacterial Proteins; C095459:EsaR protein, Pantoea stewartii; D011994:Recombinant Proteins; D014157:Transcription Factors; D012321:DNA-Directed RNA Polymerases