A Proteomic Approach to Understand the Role of the Outer Membrane Porins in the Organic Solvent-Tolerance of Pseudomonas aeruginosa PseA

ABSTRACT Multidrug efflux pumps with a broad substrate specificity make a major contribution to intrinsic and acquired multiple antibiotic resistance in Pseudomonas aeruginosa. Using genetically defined efflux pump mutants, we investigated the involvement of the three known efflux systems, MexA-MexB-OprM, MexC-MexD-OprJ, and MexE-MexF-OprN, in organic solvent tolerance in this organism. Our results showed that all three systems are capable of providing some level of tolerance to organic solvents such as n-hexane andp-xylene. Expression of MexAB-OprM was correlated with the highest levels of tolerance, and indeed, this efflux system was a major contributor to the intrinsic solvent tolerance of P. aeruginosa. Intrinsic organic solvent tolerance was compromised by a protonophore, indicating that it is substantially energy dependent. These data suggest that the efflux of organic solvents is a factor in the tolerance of P. aeruginosa to these compounds and that the multidrug efflux systems of this organism can accommodate organic solvents, as well as antibiotics.

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Role of the acrAB locus in organic solvent tolerance mediated by expression of marA, soxS, or robA in Escherichia coli.

Journal of Bacteriology ◽

10.1128/jb.179.19.6122-6126.1997 ◽

1997 ◽

Vol 179 (19) ◽

pp. 6122-6126 ◽

Cited By ~ 238

Author(s):

D G White ◽

J D Goldman ◽

B Demple ◽

S B Levy

Keyword(s):

Escherichia Coli ◽

Organic Solvent ◽

Solvent Tolerance ◽

Organic Solvent Tolerance

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Organic solvent-tolerant mutants of Pseudomonas aeruginosa display multiple antibiotic resistance

Canadian Journal of Microbiology ◽

10.1139/w98-127 ◽

1999 ◽

Vol 45 (1) ◽

pp. 18-22 ◽

Cited By ~ 29

Author(s):

Xian-Zhi Li ◽

Keith Poole

Keyword(s):

Pseudomonas Aeruginosa ◽

Organic Solvent ◽

Antimicrobial Agents ◽

Efflux Pump ◽

Environmental Pollutants ◽

Multidrug Resistant ◽

Solvent Tolerance ◽

Organic Solvent Tolerance ◽

Organic Solvent Tolerant ◽

Solvent Tolerant

Organic solvent-tolerant mutants of Pseudomonas aeruginosa selected in the presence of hexane exhibited increased resistance to a variety of structurally unrelated antimicrobial agents, including beta-lactams, fluoroquinolones, chloramphenicol, tetracycline, and novobiocin, a phenotype typical of nalB multidrug-resistant mutants. Western immunoblotting with antibodies specific to components of the three known multidrug efflux systems in P. aeruginosa demonstrated that the solvent-tolerant mutants displayed increased expression of the MexAB-OprM system and decreased expression of the MexEF-OprN system. Sequence analysis of mexR, the repressor gene of mexAB-oprM efflux operon, identified a nonsense mutation and a point mutation in the mexR genes of two solvent-tolerant mutants. These results emphasize the importance of the MexAB-OprM efflux system in organic solvent tolerance and the ability of environmental pollutants to select bacteria with a medically relevant antibiotic-resistant phenotype.Key words: Pseudomonas aeruginosa, organic solvent tolerance, multidrug resistance, MexAB-OprM efflux pump, mexR gene.

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Involvement of Outer Membrane Protein TolC, a Possible Member of the mar-sox Regulon, in Maintenance and Improvement of Organic Solvent Tolerance of Escherichia coli K-12

Journal of Bacteriology ◽

10.1128/jb.180.4.938-944.1998 ◽

1998 ◽

Vol 180 (4) ◽

pp. 938-944 ◽

Cited By ~ 128

Author(s):

Rikizo Aono ◽

Norihiko Tsukagoshi ◽

Mami Yamamoto

Keyword(s):

Escherichia Coli ◽

Membrane Protein ◽

Organic Solvent ◽

Outer Membrane ◽

Outer Membrane Protein ◽

Solvent Tolerance ◽

Organic Solvent Tolerance ◽

Tolerance Level ◽

Inner Membrane Protein ◽

K 12

ABSTRACT Escherichia coli mutants with improved organic solvent tolerance levels showed high levels of outer membrane protein TolC and inner membrane protein AcrA. The TolC level was regulated positively by MarA, Rob, or SoxS. A possible mar-rob-sox box sequence was found upstream of the tolC gene. These findings suggest that tolC is a member of the mar-sox regulon responsive to stress conditions. When a defective tolC gene was transferred to n-hexane- or cyclohexane-tolerant strains by P1 transduction, the organic solvent tolerance level was lowered dramatically to the decane-tolerant and nonane-sensitive level. The tolerance level was restored by transformation of the transductants with a wild-type tolC gene. Therefore, it is evident that TolC is essential for E. coli to maintain organic solvent tolerance.

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MexAB-OprM Efflux Pump Interaction with the Peptidoglycan of Escherichia coli and Pseudomonas aeruginosa

International Journal of Molecular Sciences ◽

10.3390/ijms22105328 ◽

2021 ◽

Vol 22 (10) ◽

pp. 5328

Author(s):

Miao Ma ◽

Margaux Lustig ◽

Michèle Salem ◽

Dominique Mengin-Lecreulx ◽

Gilles Phan ◽

...

Keyword(s):

Escherichia Coli ◽

Pseudomonas Aeruginosa ◽

Cell Division ◽

Membrane Proteins ◽

Outer Membrane ◽

Efflux Pump ◽

Gram Negative Bacteria ◽

Gram Negative ◽

Active Efflux

One of the major families of membrane proteins found in prokaryote genome corresponds to the transporters. Among them, the resistance-nodulation-cell division (RND) transporters are highly studied, as being responsible for one of the most problematic mechanisms used by bacteria to resist to antibiotics, i.e., the active efflux of drugs. In Gram-negative bacteria, these proteins are inserted in the inner membrane and form a tripartite assembly with an outer membrane factor and a periplasmic linker in order to cross the two membranes to expulse molecules outside of the cell. A lot of information has been collected to understand the functional mechanism of these pumps, especially with AcrAB-TolC from Escherichia coli, but one missing piece from all the suggested models is the role of peptidoglycan in the assembly. Here, by pull-down experiments with purified peptidoglycans, we precise the MexAB-OprM interaction with the peptidoglycan from Escherichia coli and Pseudomonas aeruginosa, highlighting a role of the peptidoglycan in stabilizing the MexA-OprM complex and also differences between the two Gram-negative bacteria peptidoglycans.

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