title: Functional relationships between the AcrA hairpin tip region and the TolC aperture tip region for the formation of the bacterial tripartite efflux pump AcrAB-TolC.
abstract: Tripartite efflux pumps found in Gram-negative bacteria are involved in antibiotic resistance and toxic-protein secretion. In this study, we show, using site-directed mutational analyses, that the conserved residues located in the tip region of the alpha-hairpin of the membrane fusion protein (MFP) AcrA play an essential role in the action of the tripartite efflux pump AcrAB-TolC. In addition, we provide in vivo functional data showing that both the length and the amino acid sequence of the alpha-hairpin of AcrA can be flexible for the formation of a functional AcrAB-TolC pump. Genetic-complementation experiments further indicated functional interrelationships between the AcrA hairpin tip region and the TolC aperture tip region. Our findings may offer a molecular basis for understanding the multidrug resistance of pathogenic bacteria.
authors.affiliation: Department of Life Science (BK21 Program), Chung-Ang University, Seoul, Republic of Korea.
authors.forename: Hong-Man
authors.initials: HM
authors.lastname: Kim
authors.forename: Yongbin
authors.initials: Y
authors.lastname: Xu
authors.forename: Minho
authors.initials: M
authors.lastname: Lee
authors.forename: Shunfu
authors.initials: S
authors.lastname: Piao
authors.forename: Se-Hoon
authors.initials: SH
authors.lastname: Sim
authors.forename: Nam-Chul
authors.initials: NC
authors.lastname: Ha
authors.forename: Kangseok
authors.initials: K
authors.lastname: Lee
mesh_terms: D000595:Amino Acid Sequence; D000667:Ampicillin / Q000494:pharmacology; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D024881:Drug Resistance, Bacterial / Q000235:genetics / Q000502:physiology; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D006090:Gram-Negative Bacteria / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D006801:Humans; D007612:Kanamycin / Q000494:pharmacology; D008074:Lipoproteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D009154:Mutation; D011550:Pseudomonas aeruginosa / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D013329:Structure-Activity Relationship; D013752:Tetracycline / Q000494:pharmacology
chemical_list: C083497:AcrA protein, E coli; D000900:Anti-Bacterial Agents; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D008074:Lipoproteins; D026901:Membrane Transport Proteins; D011994:Recombinant Proteins; C073126:tolC protein, E coli; D007612:Kanamycin; D000667:Ampicillin; D013752:Tetracycline