Functional replacement of OprJ by OprM in the MexCD-OprJ multidrug efflux system of Pseudomonas aeruginosa

Gotoh, N

doi:10.1016/s0378-1097(98)00250-x

Cited by 22 publications

(34 citation statements)

References 10 publications

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“…We cannot exclude the possibility that other outer membrane component(s) among the four remaining candidates is (are) important for function of the RND-type efflux transporters in V. cholerae. It has been reported in P. aeruginosa that several outer membrane components are present, and certain RND-type efflux transporters can utilize multiple outer membrane components (16,23,27,40). In order to understand the mechanism of drug transport via the RND-type efflux transporters, investigation of the interaction between the inner membrane component of the RND-type efflux transporter and the outer membrane component would be important.…”

Section: Discussionmentioning

confidence: 99%

Molecular Cloning and Characterization of All RND‐Type Efflux Transporters in Vibrio cholerae Non‐O1

Rahman

Matsuo

Ogawa

et al. 2007

Microbiology and Immunology

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Resistance Nodulation cell Division (RND) efflux transporters are thought to be involved in mediating multidrug resistance in Gram‐negative bacteria, including Vibrio cholerae non‐O1. There are six operons for putative RND‐type efflux transporters present in the chromosome of V. cholerae O1 including two operons, vexAB and vexCD, which had already been identified. All of the six operons were cloned from V. cholerae non‐O1, NCTC4716 by the PCR method, introduced, and expressed in cells of drug hypersusceptible Escherichia coli KAM33 (AacrAB, AydhE). Only vexEF conferred elevated minimum inhibitory concentrations (MICs) of some antimicrobial agents in the E. coli cells. However, VexEF did not confer increased MIC of any drug tested in tolC‐deficient E. coli KAM43 cells. On the other hand, when E. coli KAM43 was transformed with vexAB, vexCD or vexEF together with tolCVc of V. cholerae NCTC4716, we observed elevated MICs of various antimicrobial agents. Among them, E. coli KAM43 expressing both VexEF and TolCVc showed much higher MICs and much broader substrate specificity than the other two. We also observed ethidium efflux activity via VexEF‐TolCVc, and the activity required Na+. Thus, VexEF‐TolCVc is either a Na+‐activated or a Na+‐coupled transporter. To our knowledge, this is the first report on the requirement of Na+ for an RND‐type efflux transporter.

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Section: Discussionmentioning

confidence: 99%

Molecular Cloning and Characterization of All RND‐Type Efflux Transporters in Vibrio cholerae Non‐O1

Rahman

Matsuo

Ogawa

et al. 2007

Microbiology and Immunology

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“…In contrast to MexAB-OprM, MexCD-OprJ and MexEF-OprN do not confer resistance to ␤-lactam antibiotics (65,115). Subunit swapping experiments demonstrated that the inner membrane efflux components of the MexAB-OprM transporter are responsible for the ␤-lactam specificity of the multidrug efflux pumps in P. aeruginosa (66,155,240). Recently, two new genes mediating resistance to quinolones, aminoglycosides, and macrolide antibiotics were cloned from the chromosome of P. aeruginosa (6,158).…”

Section: Resistance-nodulation-cell Division Familymentioning

confidence: 99%

“…This specificity for hydrophilic quinolones was also observed for PmrA and NorM (63,163). However, EmrB and VceB confer resistance only to hydrophobic quinolones, whereas LmrA and the multidrug transporters of the RND family transport both hydrophilic and hydrophobic quinolones (37,66,135,158,200,205). In addition to conferring resistance, the overexpression of multidrug transporters can also cause increased drug sensitivity.…”

Section: Antibiotic Resistancementioning

confidence: 99%

Molecular Properties of Bacterial Multidrug Transporters

Putman

Veen

Konings

2000

Microbiol Mol Biol Rev

695

586

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SUMMARY One of the mechanisms that bacteria utilize to evade the toxic effects of antibiotics is the active extrusion of structurally unrelated drugs from the cell. Both intrinsic and acquired multidrug transporters play an important role in antibiotic resistance of several pathogens, including Neisseria gonorrhoeae, Mycobacterium tuberculosis, Staphylococcus aureus, Streptococcus pneumoniae, Pseudomonas aeruginosa, and Vibrio cholerae. Detailed knowledge of the molecular basis of drug recognition and transport by multidrug transport systems is required for the development of new antibiotics that are not extruded or of inhibitors which block the multidrug transporter and allow traditional antibiotics to be effective. This review gives an extensive overview of the currently known multidrug transporters in bacteria. Based on energetics and structural characteristics, the bacterial multidrug transporters can be classified into five distinct families. Functional reconstitution in liposomes of purified multidrug transport proteins from four families revealed that these proteins are capable of mediating the export of structurally unrelated drugs independent of accessory proteins or cytoplasmic components. On the basis of (i) mutations that affect the activity or the substrate specificity of multidrug transporters and (ii) the three-dimensional structure of the drug-binding domain of the regulatory protein BmrR, the substrate-binding site for cationic drugs is predicted to consist of a hydrophobic pocket with a buried negatively charged residue that interacts electrostatically with the positively charged substrate. The aromatic and hydrophobic amino acid residues which form the drug-binding pocket impose restrictions on the shape and size of the substrates. Kinetic analysis of drug transport by multidrug transporters provided evidence that these proteins may contain multiple substrate-binding sites.

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“…In this vein, it is worth noting that pumps of the RND-MFP-OMF type show considerable flexibility in regard to the OMF component that can be used in assembling a functional tripartite efflux system. Studies of artificially created hybrid multidrug efflux systems in P. aeruginosa have confirmed, for example, that OprM can replace the OprJ (19,74) and OprN (46) OMF components of the MexCD-OprJ and MexEF-OprN efflux systems, respectively. Similarly, OprJ can replace the OprM component of MexAB-OprM (74), and the E. coli OMF TolC can replace OprJ (73).…”

Section: Discussionmentioning

confidence: 97%

Assembly of the MexAB-OprM Multidrug Efflux System of Pseudomonas aeruginosa : Identification and Characterization of Mutations in mexA Compromising MexA Multimerization and Interaction with MexB

Nehme

Elliot

et al. 2004

J Bacteriol

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The membrane fusion protein (MFP) component, MexA, of the MexAB-OprM multidrug efflux system of P. aeruginosa is proposed to link the inner (MexB) and outer (OprM) membrane components of this pump as a probable oligomer. A cross-linking approach confirmed the in vivo interaction of MexA and MexB, while a LexA-based assay for assessing protein-protein interaction similarly confirmed MexA multimerization. Mutations compromising the MexA contribution to antibiotic resistance but yielding wild-type levels of MexA were recovered and shown to map to two distinct regions within the N-and C-terminal halves of the protein. Most of the N-terminal mutations occurred at residues that are highly conserved in the MFP family (P68, G72, L91, A108, L110, and V129), consistent with these playing roles in a common feature of these proteins (e.g., oligomerization). In contrast, the majority of the C-terminal mutations occurred at residues poorly conserved in the MFP family (V264, N270, H279, V286, and G297), with many mapping to a region of MexA that corresponds to a region in the related MFP of Escherichia coli, AcrA, that is implicated in binding to its Pseudomonas aeruginosa is an opportunistic human pathogen characterized by an innate resistance to multiple antimicrobials (21). The resistance has historically been attributed to the presence in this organism of an outer membrane (OM) of low permeability (55), but it is increasingly clear that resistance owes much to the operation of broadly specific, so-called multidrug efflux systems (58-60, 64) that work synergistically with limited OM permeability (18,40,60). Several multidrug efflux systems in P. aeruginosa have been described to date (61), although the major system contributing to intrinsic multidrug resistance is encoded by the mexAB-oprM operon (38). Hyperexpression of this system also occurs in so-called nalB (27, 28, 75, 88)-and nalC (75, 88)-type multidrug-resistant mutants. MexAB-OprM accommodates a broad range of structurally diverse antimicrobials, including dyes, detergents, inhibitors of fatty acid biosynthesis, organic solvents, disinfectants, and clinically relevant antibiotics (10,34,37,39,41,42,48,70,74,74,76), and is implicated in the export of homoserine lactones involved in quorum sensing (17, 57) and, possibly, virulence factors (22).The MexAB-OprM efflux system, like the other tripartite Mex efflux systems in P. aeruginosa, consists of an inner membrane (IM) drug-proton antiporter of the resistance-nodulation-cell division (RND) family (MexB), an OM channel-forming component (OprM; also called OM factor [OMF]), and a periplasmic membrane fusion protein (MFP) (MexA) (58, 86). Crystal structures have not yet been reported for any of the efflux components of P. aeruginosa, although structures are available for the homologous OM (TolC [35]) and RND (AcrB [52]) components of the Mex-like AcrAB-TolC multidrug efflux system of Escherichia coli. The TolC channel is a trimer and spans both the OM (as a ␤-barrel) and periplasm (as a ␣-helical barrel) (35). Measuri...

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Functional replacement of OprJ by OprM in the MexCD-OprJ multidrug efflux system of Pseudomonas aeruginosa

Cited by 22 publications

References 10 publications

Molecular Cloning and Characterization of All RND‐Type Efflux Transporters in Vibrio cholerae Non‐O1

Molecular Cloning and Characterization of All RND‐Type Efflux Transporters in Vibrio cholerae Non‐O1

Molecular Properties of Bacterial Multidrug Transporters

Assembly of the MexAB-OprM Multidrug Efflux System of Pseudomonas aeruginosa : Identification and Characterization of Mutations in mexA Compromising MexA Multimerization and Interaction with MexB

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