AcrA is a highly asymmetric protein capable of spanning the periplasm 1 1Edited by I. B. Holland

Zgurskaya, Helen I.; Nikaido, Hiroshi

doi:10.1006/jmbi.1998.2313

Cited by 190 publications

(194 citation statements)

References 31 publications

Supporting

Mentioning

184

Contrasting

Order By: Relevance

“…Various adaptors from E. coli and P. aeruginosa were expressed in a soluble form with the N-terminal Cys residue (residue 1 of the protein after removal of the periplasmic signal sequence) mutated to Ser to prevent addition of the fatty acid. Both MexA and its homologue AcrA are functional in the absence of this membrane linkage (14,21) and behave as monomers in solution. Crystallization trials were successful for MexA, and data were collected from crystals of selenomethionine-substituted protein to a 3.0-Å resolution.…”

Section: Resultsmentioning

confidence: 99%

“…Several models have been suggested to explain this coupling. In the membrane fusion protein model, the two putative ␣-helices of the adaptor are predicted to function like a viral fusion protein, with coiled-coil formation driving the inner and outer membranes of the bacteria into close proximity, bringing together the opened exit duct and inner membrane transporter (6,14). An alternative suggestion is that the ␣-helices of the adaptor protein form a stable coiled-coil (13).…”

mentioning

confidence: 99%

See 1 more Smart Citation

Structure of the periplasmic component of a bacterial drug efflux pump

Higgins

Bokma

Koronakis

et al. 2004

Proc. Natl. Acad. Sci. U.S.A.

240

251

View full text Add to dashboard Cite

Multidrug resistance among Gram-negative bacteria is conferred by three-component membrane pumps that expel diverse antibiotics from the cell. These efflux pumps consist of an inner membrane transporter such as the AcrB proton antiporter, an outer membrane exit duct of the TolC family, and a periplasmic protein known as the adaptor. We present the x-ray structure of the MexA adaptor from the human pathogen Pseudomonas aeruginosa. The elongated molecule contains three linearly arranged subdomains; a 47-Å-long ␣-helical hairpin, a lipoyl domain, and a six-stranded ␤-barrel. In the crystal, hairpins of neighboring MexA monomers pack side-by-side to form twisted arcs. We discuss the implications of the packing of molecules within the crystal. On the basis of the structure and packing, we suggest a model for the key periplasmic interaction between the outer membrane channel and the adaptor protein in the assembled drug efflux pump.

show abstract

Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

Structure of the periplasmic component of a bacterial drug efflux pump

Higgins

Bokma

Koronakis

et al. 2004

Proc. Natl. Acad. Sci. U.S.A.

240

251

View full text Add to dashboard Cite

show abstract

“…The members of this family interact with a membrane fusion protein (MFP) and an outer membrane protein and this complex thus allows the efflux of drugs across the inner (cytoplasmic) and outer membrane into the surrounding medium (Putman et al, 2000). The MFP proteins probably induce the fusion of the inner and the outer membrane, and thus form a channel-like structure through the periplasmic space (Zgurskaya and Nikaido, 1999). The acrAB locus consists of two genes: the gene acrA, coding for a MFP protein and the gene acrB, coding for a 12-transmembrane α-helix RND protein (Dinh et al, 1994;Zgurskaya and Nikaido, 1999).…”

Section: Multidrug Transportersmentioning

confidence: 99%

“…The MFP proteins probably induce the fusion of the inner and the outer membrane, and thus form a channel-like structure through the periplasmic space (Zgurskaya and Nikaido, 1999). The acrAB locus consists of two genes: the gene acrA, coding for a MFP protein and the gene acrB, coding for a 12-transmembrane α-helix RND protein (Dinh et al, 1994;Zgurskaya and Nikaido, 1999). Together with the membrane protein, TolC, they form the AcrAB efflux system (Fralick, 1996).…”

Section: Multidrug Transportersmentioning

confidence: 99%

Tetracyclines in veterinary medicine and bacterial resistance to them

Michalova¹,

PNovotna²,

Schlegelová³

2004

Vet. Med.

121

View full text Add to dashboard Cite

Since their discovery in 1945, tetracyclines have been used extensively in the therapy and prophylaxis of infectious diseases and as growth promoters. These wide applications have led to the equally fast spread of tetracycline resistant strains of gram-positive and gram-negative bacterial genera, including strains belonging to pathogenic as well as nonpathogenic species. Nonpathogenic bacteria could act as a reservoir of resistance determinants, which can be disseminated by horizontal transfer into pathogens. More than thirty different tetracycline resistance genes have been characterized. They encode two major mechanisms of resistance: 1 -active efflux of the antibiotic, and 2 -protection of ribosomes. Further mechanisms of tetracycline resistance include enzymatic inactivation of antibiotic, permeability barriers, mutations or multidrug transporter systems. Effective horizontal spread is favoured by the location of tetracycline resistance genes on mobile genetic elements such as plasmids and transposons. Their exchange, enhanced by the use of tetracyclines, is observed between bacteria of the same or different species and genera as well. Thus, questions of reevaluating and global reducing of tetracyclines in human and animal healthcare and food production are extensively discussed.

show abstract

“…It is an antiporter deriving the energy for the transport from the proton gradient. The second component is an outer membrane protein which is thought to be connected with the efflux pump by a third component, called a periplasmic link protein or membrane fusion protein (29). These three proteins form a channel which permits the extrusion of substrate molecules directly from the cytoplasm or the periplasm into the external medium (20).…”

mentioning

confidence: 99%

Amino Acid Residues Essential for Function of the MexF Efflux Pump Protein of Pseudomonas aeruginosa

Aires¹,

Pechère²,

Delden³

et al. 2002

Antimicrob Agents Chemother

View full text Add to dashboard Cite

At least four broad-spectrum efflux pumps (Mex) are involved in elevated intrinsic antibiotic resistance as well as in acquired multidrug resistance in Pseudomonas aeruginosa. Substrate specificity of the Mex pumps has been shown to be determined by the cytoplasmic membrane component (MexB, MexD, MexF, and MexY) of the tripartite efflux pump system. Alignment of their amino acid sequences with those of the homologous AcrB and AcrD pump proteins of Escherichia coli showed conservation of five charged amino acid residues located in or next to transmembrane segments (TMS). These residues were mutated in the MexF gene by site-directed mutagenesis and replaced by residues of opposite or neutral charge. MexF proteins containing combined D410A and A411G substitutions located in TMS4 were completely inactive. Similarly, the substitutions E417K (next to TMS4) and K951E (TMS10) also caused loss of activity towards all tested antibiotics. The substitution E349K in TMS2 resulted in a MexF mutant protein which was unable to transport trimethoprim and quinolones but retained partial activity for the transport of chloramphenicol. All mutated MexF proteins were expressed at comparable levels when tested by Western blot analysis. It is concluded that charged residues located in or close to TMS are essential for proper function of MexF.Drug efflux systems endow mammalian cells, yeast, fungi, and bacteria with the ability to become resistant to a variety of chemotherapeutic and antimicrobial agents. Based on their primary amino acid structure, bacterial drug efflux systems can be divided into four major groups: the major facilitator family (14), the staphylococcal (small) multidrug resistance pumps (21), the ATP-binding cassette transporters (3), and the resistance-nodulation-cell division (RND) family (25). Phylogenetically, the latter group can be further subdivided into three clusters which correlate with substrate specificity (26): one containing proteins responsible for heavy metal efflux (CzcA and CnrA), a second involved in secretion of nodulation factors (NolFGH), and the third cluster representing multidrug efflux pumps (Acr, Mex, and Mtr) from various gram-negative bacteria.The Acr, Mex, and Mtr pumps described for Escherichia coli, Pseudomonas aeruginosa, and Neisseria spp., respectively, are composed of three individual proteins. The actual pump component is a 12-transmembrane-segment protein located in the cytoplasmic membrane (6, 7). It is an antiporter deriving the energy for the transport from the proton gradient. The second component is an outer membrane protein which is thought to be connected with the efflux pump by a third component, called a periplasmic link protein or membrane fusion protein (29). These three proteins form a channel which permits the extrusion of substrate molecules directly from the cytoplasm or the periplasm into the external medium (20). Several models have been proposed to explain the interactions between the three components of these efflux systems (10, 30).The Mex pumps of P. aeruginosa...

show abstract

AcrA is a highly asymmetric protein capable of spanning the periplasm 1 1Edited by I. B. Holland

Cited by 190 publications

References 31 publications

Structure of the periplasmic component of a bacterial drug efflux pump

Structure of the periplasmic component of a bacterial drug efflux pump

Tetracyclines in veterinary medicine and bacterial resistance to them

Amino Acid Residues Essential for Function of the MexF Efflux Pump Protein of Pseudomonas aeruginosa

Contact Info

Product

Resources

About