Mutations Affecting DNA-Binding Activity of theMexR Repressor of mexR-mexA-mexB-oprM OperonExpression
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چکیده
منابع مشابه
Mutations affecting DNA-binding activity of the MexR repressor of mexR-mexA-mexB-oprM operon expression.
We have isolated 25 MexR mutants that retained their dimerizing ability but were unable to bind mexOP DNA. Surprisingly, 20 mutations were located in the hydrophobic core region at alpha4, W1, alpha2, alpha3, and beta2, and only 3 were in positively charged residues. These results verified that DNA binding is mediated by distinct regions of MexR and showed the importance of the hydrophobic core...
متن کاملExpression of the multidrug resistance operon mexA-mexB-oprM in Pseudomonas aeruginosa: mexR encodes a regulator of operon expression.
The region upstream of the multiple antibiotic resistance efflux operon mexA-mexB-oprM in Pseudomonas aeruginosa was sequenced, and a gene, mexR, was identified. The predicted MexR product contains 147 amino acids with a molecular mass of 16,964 Da, which is consistent with the observed size of the overexpressed mexR gene product. MexR was homologous to MarR, the repressor of MarA-dependent mul...
متن کاملsiRNA-mediated gene silencing of MexB from the MexA-MexB-OprM efflux pump in Pseudomonas aeruginosa
To gain insights into the effect of MexB gene under the short interfering RNA (siRNA), we synthesized 21 bp siRNA duplexes against the MexB gene. RT-PCR was performed to determine whether the siRNA inhibited the expression of MexB mRNA. Changes in antibiotic susceptibility in response to siRNA were measured by the E-test method. The efficacy of siRNAs was determined in a murine model of chronic...
متن کاملThe mexR repressor of the mexAB-oprM multidrug efflux operon in Pseudomonas aeruginosa: characterization of mutations compromising activity.
Mutations in mexR yield a multidrug resistance phenotype in nalB mutants of Pseudomonas aeruginosa as a result of derepression of the mexAB-oprM multidrug efflux operon. MexR produced by several nalB strains carried single amino acid changes that compromised MexR stability or its ability to dimerize. Changes at residues L95 and R21, however, produced a stable MexR protein capable of dimerizatio...
متن کاملInteraction of the MexA and MexB components of the MexAB-OprM multidrug efflux system of Pseudomonas aeruginosa: identification of MexA extragenic suppressors of a T578I mutation in MexB.
A T578I mutation in MexB compromised the protein's contribution to antimicrobial resistance and negatively impacted its interaction with MexA. Mutations causing single amino acid changes in the C-terminal domain of MexA (R221H, L245F, E254K, and V259I) suppressed the antimicrobial susceptibility of a MexB(T578I)-expressing Pseudomonas aeruginosa strain and restored a MexA interaction with MexB(...
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ژورنال
عنوان ژورنال: Journal of Bacteriology
سال: 2003
ISSN: 0021-9193,1098-5530
DOI: 10.1128/jb.185.24.7302.2003