Disease relevance of mexB

• A Pseudomonas aeruginosa strain carrying an insertion of an omega Hg interposon in the mexB gene (mexB::omega Hg; strain K879) produced markedly reduced but still detectable levels of OprM, the product of the third gene of the mexAB-oprM multidrug efflux operon [1].
• A homologue of the mexAB-oprM multidrug efflux operon of Pseudomonas aeruginosa, smeABC, was cloned from Stenotrophomonas maltophilia by using, as a probe, a PCR product amplified from this organism with primers based on the mexB sequence [2].

High impact information on mexB

• One of these disruption mutants (in bmeB, the mexB homolog) was more susceptible than the parental strain to certain cephems, polypeptide antibiotics, fusidic acid, novobiocin, and puromycin [3].
• When two halves of MexB were coexpressed from independent open reading frames, the cells lacking chromosomal mexB exhibited restored antibiotic resistance at a level close to that in the cells producing a full-length MexB [4].
• Using isogenic emrE(Pae), mexAB-oprM, and/or mexB deletion mutants, the contributions of the EmrE protein and the MexAB-OprM efflux system to drug resistance in P. aeruginosa were assessed by a drug susceptibility test carried out in a low-ionic-strength medium, Difco nutrient broth [5].
• Of 100 mutants that expressed wild-type levels of MexB and showed increased susceptibility to one or more of carbenicillin, chloramphenicol, nalidixic acid, and novobiocin, the mexB genes of a representative 46 were sequenced, and 19 unique single mutations were identified [6].
• In nalB mutants, which overexpress OprM, we observed a four- to eightfold increase in the expression of mexA, mexB, and oprM genes [7].

Chemical compound and disease context of mexB

• Meropenem susceptibility breakpoint for Pseudomonas aeruginosa strains hyperproducing mexB mRNA [8].

Biological context of mexB

• The partial open reading frame shows homology at the protein level with the C terminus of the protein product of mexB [9].

Associations of mexB with chemical compounds

• Increased transcription of mexB generally correlated well with meropenem resistance [10].

Other interactions of mexB

• Furthermore, one meropenem-susceptible isolate showed significant increase in mexB transcription, but no mexR mutations [10].

Analytical, diagnostic and therapeutic context of mexB

• RT-PCR showed that 10 and five isolates over-expressed mexB and mexY, respectively [11].

References