The MtrR repressor binds the DNA sequence between the mtrR and mtrC genes of Neisseria gonorrhoeae.
Gonococcal resistance to antimicrobial hydrophobic agents (HAs) is due to energy-dependent removal of HAs from the bacterial cell by the MtrCDE membrane-associated efflux pump. The mtrR (multiple transferrable resistance Regulator) gene encodes a putative transcriptional repressor protein (MtrR) believed to be responsible for regulation of mtrCDE gene expression. Gel mobility shift and DNase I footprint assays that used a maltose-binding protein (MBP)-MtrR fusion protein demonstrated that the MtrR repressor is capable of specifically binding the DNA sequence between the mtrR and mtrC genes. This binding site was localized to a 26-nucleotide stretch that includes the promoter utilized for mtrCDE transcription and, on the complementary strand, a 22-nucleotide stretch that contains the -35 region of the mtrR promoter. A single transition mutation (A-->G) within the MtrR-binding site decreased the affinity of the target DNA for MtrR and enhanced gonococcal resistance to HAs when introduced into HA-susceptible strain FA19 by transformation. Since this mutation enhanced expression of the mtrCDE gene complex but decreased expression of the mtrR gene, the data are consistent with the notion that MtrR acts as a transcriptional repressor of the mtrCDE efflux pump protein genes.
Lucas
C E
CE
Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta, Georgia 30322, USA.
Balthazar
J T
JT
Hagman
K E
KE
Shafer
W M
WM
D001426:Bacterial Proteins; D001483:Base Sequence; D001665:Binding Sites; D002352:Carrier Proteins / Q000235:genetics*; D004269:DNA, Bacterial / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D005287:Ferredoxin-NADP Reductase; D008074:Lipoproteins / Q000235:genetics*; D008565:Membrane Proteins / Q000235:genetics*; D026901:Membrane Transport Proteins; D008969:Molecular Sequence Data; D009154:Mutation; D009344:Neisseria gonorrhoeae / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*
D001426:Bacterial Proteins; D002352:Carrier Proteins; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; D008074:Lipoproteins; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; C094589:MtrC protein, Neisseria gonorrhoeae; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; C087450:mtrR protein, Neisseria gonorrhoeae; C111241:methionine synthase reductase; D005287:Ferredoxin-NADP Reductase