title: Characterization of the RND-type multidrug efflux pump MexAB-OprM of the plant pathogen Pseudomonas syringae.
abstract: In gram-negative bacteria, transporters belonging to the RND family are the transporters most relevant for resistance to antimicrobial compounds. In Pseudomonas aeruginosa, a clinically important pathogen, the RND-type pump MexAB-OprM has been recognized as one of the major multidrug efflux systems. Here, homologues of MexAB-OprM in the plant pathogens Pseudomonas syringae pv. phaseolicola 1448A, P. syringae pv. syringae B728a, and P. syringae pv. tomato DC3000 were identified, and mexAB-oprM-deficient mutants were generated. Determination of MICs revealed that mutation of MexAB-OprM dramatically reduced the tolerance to a broad range of antimicrobials. Moreover, the ability of the mexAB-oprM-deficient mutants to multiply in planta was reduced. RNA dot blot hybridization revealed growth-dependent regulation of the mexAB-oprM operon in P. syringae; the expression of this operon was maximal in early exponential phase and decreased gradually during further growth.
authors.affiliation: School of Engineering and Science, Jacobs University Bremen, Bremen, Germany.
authors.forename: Savina O
authors.initials: SO
authors.lastname: Stoitsova
authors.forename: Yvonne
authors.initials: Y
authors.lastname: Braun
authors.forename: Matthias S
authors.initials: MS
authors.lastname: Ullrich
authors.forename: Helge
authors.initials: H
authors.lastname: Weingart
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D017360:Arabidopsis / Q000382:microbiology; D001426:Bacterial Proteins / Q000235:genetics*; D001693:Biological Transport, Active / Q000235:genetics; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics*; D004996:Ethidium / Q000378:metabolism; D017353:Gene Deletion; D020869:Gene Expression Profiling; D026901:Membrane Transport Proteins / Q000235:genetics*; D008826:Microbial Sensitivity Tests; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000235:genetics*; D027805:Phaseolus / Q000382:microbiology; D044224:Pseudomonas syringae / Q000187:drug effects / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D004996:Ethidium; D026901:Membrane Transport Proteins; D027425:ATP-Binding Cassette, Sub-Family C Proteins