title: Characterization of bacterial drug antiporters homologous to mammalian neurotransmitter transporters.
abstract: Multidrug transporters are ubiquitous proteins, and, based on amino acid sequence similarities, they have been classified into several families. Here we characterize a cluster of archaeal and bacterial proteins from the major facilitator superfamily (MFS). One member of this family, the vesicular monoamine transporter (VMAT) was previously shown to remove both neurotransmitters and toxic compounds from the cytoplasm, thereby conferring resistance to their effects. A BLAST search of the available microbial genomes against the VMAT sequence yielded sequences of novel putative multidrug transporters. The new sequences along with VMAT form a distinct cluster within the dendrogram of the MFS, drug-proton antiporters. A comparison with other proteins in the family suggests the existence of a potential ion pair in the membrane domain. Three of these genes, from Mycobacterium smegmatis, Corynebacterium glutamicum, and Halobacterium salinarum, were cloned and functionally expressed in Escherichia coli. The proteins conferred resistance to fluoroquinolones and chloramphenicol (at concentrations two to four times greater than that of the control). Measurement of antibiotic accumulation in cells revealed proton motive force-dependent transport of those compounds.
authors.affiliation: Department of Biological Chemistry, Alexander Silberman Institute of Life Sciences, Hebrew University of Jerusalem, Jerusalem, Israel. Shimon.Schuldiner@huji.ac.il.
authors.forename: Eyal
authors.initials: E
authors.lastname: Vardy
authors.forename: Sonia
authors.initials: S
authors.lastname: Steiner-Mordoch
authors.forename: Shimon
authors.initials: S
authors.lastname: Schuldiner
mesh_terms: D000595:Amino Acid Sequence; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D017920:Antiporters / Q000737:chemistry / Q000235:genetics* / Q000502:physiology; D001105:Archaea / Q000378:metabolism*; D001419:Bacteria / Q000378:metabolism*; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D001692:Biological Transport; D002701:Chloramphenicol / Q000494:pharmacology; D003001:Cloning, Molecular; D048230:Corynebacterium glutamicum / Q000235:genetics; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics* / Q000502:physiology; D004926:Escherichia coli / Q000187:drug effects; D024841:Fluoroquinolones / Q000494:pharmacology; D005798:Genes, Bacterial; D019617:Halobacterium salinarum / Q000235:genetics; D008969:Molecular Sequence Data; D020102:Mycobacterium smegmatis / Q000235:genetics; D010802:Phylogeny; D011487:Protein Conformation; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid
chemical_list: D000900:Anti-Bacterial Agents; D017920:Antiporters; D001426:Bacterial Proteins; D024841:Fluoroquinolones; D011994:Recombinant Proteins; D002701:Chloramphenicol