title: The transcriptional regulator gene phrR in Sinorhizobium meliloti WSM419 is regulated by low pH and other stresses.
abstract: The phrR gene in Sinorhizobium meliloti (previously known as Rhizobium meliloti) WSM419, directly downstream from actA, is induced by low pH or certain stresses (e.g. high concentrations of Zn2+, Cu2+, H2O2 or ethanol), but not in stationary phase or by other stresses (e.g. phosphate limitation, elevated temperature, high concentrations of sucrose or iron). A DNA fragment containing the wild-type phrR gene could not be cloned and inverse PCR was therefore used to amplify a 3.5 kb BamHI fragment containing phrR from the mutant S. meliloti TG2-6 (actA::Tn5). DNA fragments from a BamHI/SalI digest of the amplified product were cloned into pUK21 and sequenced. The phrR open reading frame contiguous to actA appears to code for a 15.2 kDa protein showing significant identity with the proteins encoded by y4wC and y4aM in Rhizobium sp. NGR234. All three proteins resemble transcriptional regulators in containing a DNA-binding helix-turn-helix motif similar to that reported for URF4 in Rhodospirillum rubrum and repressors in coliphage.
authors.forename: Wayne G
authors.initials: WG
authors.lastname: Reeve
authors.forename: Ravi P
authors.initials: RP
authors.lastname: Tiwari
authors.forename: Cheryl M
authors.initials: CM
authors.lastname: Wong
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Dilworth
authors.forename: Andrew R
authors.initials: AR
authors.lastname: Glenn
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics; D001483:Base Sequence; D003001:Cloning, Molecular; D015964:Gene Expression Regulation, Bacterial; D006863:Hydrogen-Ion Concentration; D008565:Membrane Proteins / Q000235:genetics; D008969:Molecular Sequence Data; D012097:Repressor Proteins / Q000235:genetics*; D017386:Sequence Homology, Amino Acid; D016962:Sinorhizobium meliloti / Q000235:genetics*
chemical_list: D001426:Bacterial Proteins; D008565:Membrane Proteins; C118506:PhrR protein, Sinorhizobium meliloti; D012097:Repressor Proteins; C072980:actA protein, Listeria monocytogenes