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The Role of Gene Elongation in the Evolution of Histidine Biosynthetic Genes. Microorganisms 2020; 8:microorganisms8050732. [PMID: 32414216 PMCID: PMC7284861 DOI: 10.3390/microorganisms8050732] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Revised: 05/07/2020] [Accepted: 05/11/2020] [Indexed: 11/29/2022] Open
Abstract
Gene elongation is a molecular mechanism consisting of an in-tandem duplication of a gene and divergence and fusion of the two copies, resulting in a gene constituted by two divergent paralogous modules. The aim of this work was to evaluate the importance of gene elongation in the evolution of histidine biosynthetic genes and to propose a possible evolutionary model for some of them. Concerning the genes hisA and hisF, which code for two homologous (β/α)8-barrels, it has been proposed that the two extant genes could be the result of a cascade of gene elongation/domain shuffling events starting from an ancestor gene coding for just one (β/α) module. A gene elongation event has also been proposed for the evolution of hisB and hisD; structural analyses revealed the possibility of an early elongation event, resulting in the repetition of modules. Furthermore, it is quite possible that the gene elongations responsible for the evolution of the four proteins occurred before the earliest phylogenetic divergence. In conclusion, gene elongation events seem to have played a crucial role in the evolution of the histidine biosynthetic pathway, and they may have shaped the structures of many genes during the first steps of their evolution.
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2
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The Structure and Function of OxlT, the Oxalate Transporter of Oxalobacter formigenes. J Membr Biol 2014; 248:641-50. [DOI: 10.1007/s00232-014-9728-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Accepted: 09/05/2014] [Indexed: 01/01/2023]
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3
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Abstract
The use of tetracycline over the past few decades has been accompanied by a drastic increase in the frequency of tetracycline resistance in a wide range of bacterial species and genera. A diversity of resistance determinants is found in the microbial world, coding for markedly different mechanisms of resistance. The recent analysis of one family of resistance determinants provides evidence for intergenic and intragenic coevolutionary changes as well as for an unusual evolutionary history of duplication and divergence in function of domains within a single locus.
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Affiliation(s)
- R Johnson
- Rebecca Johnson and Julian Adams are at the Dept of Biology, University of Michigan, Ann Arbor, MI 48109-1048, USA
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4
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Fani R, Fondi M. Origin and evolution of metabolic pathways. Phys Life Rev 2009; 6:23-52. [PMID: 20416849 DOI: 10.1016/j.plrev.2008.12.003] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2008] [Revised: 11/27/2008] [Accepted: 12/01/2008] [Indexed: 10/21/2022]
Abstract
The emergence and evolution of metabolic pathways represented a crucial step in molecular and cellular evolution. In fact, the exhaustion of the prebiotic supply of amino acids and other compounds that were likely present in the ancestral environment, imposed an important selective pressure, favoring those primordial heterotrophic cells which became capable of synthesizing those molecules. Thus, the emergence of metabolic pathways allowed primitive organisms to become increasingly less-dependent on exogenous sources of organic compounds. Comparative analyses of genes and genomes from organisms belonging to Archaea, Bacteria and Eukarya revealed that, during evolution, different forces and molecular mechanisms might have driven the shaping of genomes and the arisal of new metabolic abilities. Among these gene elongations, gene and operon duplications undoubtedly played a major role since they can lead to the (immediate) appearance of new genetic material that, in turn, might undergo evolutionary divergence giving rise to new genes coding for new metabolic abilities. Gene duplication has been invoked in the different schemes proposed to explain why and how the extant metabolic pathways have arisen and shaped. Both the analysis of completely sequenced genomes and directed evolution experiments strongly support one of them, i.e. the patchwork hypothesis, according to which metabolic pathways have been assembled through the recruitment of primitive enzymes that could react with a wide range of chemically related substrates. However, the analysis of the structure and organization of genes belonging to ancient metabolic pathways, such as histidine biosynthesis and nitrogen fixation, suggested that other different hypothesis, i.e. the retrograde hypothesis or the semi-enzymatic theory, may account for the arisal of some metabolic routes.
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Affiliation(s)
- Renato Fani
- Laboratory of Microbial and Molecular Evolution, Department of Evolutionary Biology, Via Romana 17-19, University of Florence, Italy
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5
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Sapunaric FM, Levy SB. Substitutions in the interdomain loop of the Tn10 TetA efflux transporter alter tetracycline resistance and substrate specificity. Microbiology (Reading) 2005; 151:2315-2322. [PMID: 16000721 DOI: 10.1099/mic.0.27997-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Cysteine replacement of Asp190, Glu192 and Ser201 residues in the cytoplasmic interdomain loop of the TetA(B) tetracycline efflux antiporter from Tn10 reduces tetracycline resistance [Tamura, N., Konishi, S., Iwaki, S., Kimura-Someya, T., Nada, S. & Yamaguchi, A. (2001). J Biol Chem 276, 20330-20339]. It was found that these Cys substitutions altered the substrate specificity of TetA(B), increasing the relative resistance to doxycycline and minocycline over that to tetracycline by three- to sixfold. Substitutions of Asp190 and Glu192 by Ala, Asn and Gln also impaired the ability of TetA(B) to mediate tetracycline resistance while Ser201Ala and Ser201Thr substitutions did not. A Leu9Phe substitution in the first transmembrane helix of TetA(B) suppressed the Ser201Cys mutation, undoing the alterations in resistance and specificity. That the interdomain loop might contact substrate during transport, as is suggested from its role in substrate specificity, is unexpected considering that the primary sequence in the loop is not conserved among a group of otherwise homologous TetA proteins. However, in the interdomain loop of 11 of 14 homologous TetA efflux proteins, computational analysis revealed a short alpha-helix, which includes some residues affecting activity and substrate specificity. Perhaps this conserved secondary structure accounts for the role of the non-conserved interdomain loop in TetA function.
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Affiliation(s)
- Frédéric M Sapunaric
- The Center for Adaptation Genetics and Drug Resistance and Department of Molecular Biology and Microbiology, Tufts University School of Medicine, 136 Harrison Ave, Boston, MA 02111, USA
| | - Stuart B Levy
- The Center for Adaptation Genetics and Drug Resistance and Department of Molecular Biology and Microbiology, Tufts University School of Medicine, 136 Harrison Ave, Boston, MA 02111, USA
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6
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Lagerstedt JO, Voss JC, Wieslander A, Persson BL. Structural modeling of dual-affinity purified Pho84 phosphate transporter. FEBS Lett 2005; 578:262-8. [PMID: 15589830 DOI: 10.1016/j.febslet.2004.11.012] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2004] [Revised: 10/20/2004] [Accepted: 11/04/2004] [Indexed: 11/16/2022]
Abstract
The phosphate transporter Pho84 of Saccharomyces cerevisiae is predicted to contain 12 transmembrane (TM) regions, divided into two partially duplicated parts of 6 TM segments. The three-dimensional (3D) organization of the Pho84 protein has not yet been determined. However, the 3D crystal structure of the Escherichia coli MFS glycerol-3-phosphate/phosphate antiporter, GlpT, and lactose transporter, LacY, has recently been determined. On the basis of extensive prediction and fold recognition analyses (at the MetaServer), GlpT was proposed as the best structural template on which the arrangement of TM segments of the Pho84 transporter was fit, using the comparative structural modeling program MODELLER. To initiate an evaluation of the appropriateness of the Pho84 model, we have performed two direct tests by targeting spin labels to putative TM segments 8 and 12. Electron paramagnetic resonance spectroscopy was then applied on purified and spin labeled Pho84. The line shape from labels located at both positions is consistent with the structural environment predicted by the template-generated model, thus supporting the model.
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Affiliation(s)
- Jens O Lagerstedt
- Department of Chemistry and Biomedical Sciences, Kalmar University, S-391 82 Kalmar, Sweden
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7
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Guillaume G, Ledent V, Moens W, Collard JM. Phylogeny of Efflux-Mediated Tetracycline Resistance Genes and Related Proteins Revisited. Microb Drug Resist 2004; 10:11-26. [PMID: 15140389 DOI: 10.1089/107662904323047754] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
A SRS search in the GenBank/EMBL databases for entire genes encoding efflux-mediated resistance allocated to a recognized tetracycline determinant revealed the existence of at least 87 genes. DNA-based and protein sequence analyses of representatives from the different efflux-mediated tetracycline determinant groups were performed and allowed us to propose a revision of the current grouping on the basis of our new evolutionary trees. On the other hand, similarity, topology, and hydropathy analyses of some representatives from 12-transmembrane segments (TMS) and 14-TMS proteins lead us to perform meaningful sequence alignments of recognized or putative 12-TMS and 14-TMS proteins truncated to their first 200 amino acids (alpha-domain of the protein). For all aligned truncated proteins, including old and recently discovered tetracycline resistance determinants, significant similarities along this segment were demonstrated and three new conserved motifs identified, reinforcing the hypothesis of a common ancestry for the alpha-domain of all tetracycline-efflux pumps.
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Affiliation(s)
- Gilliane Guillaume
- Section of Biosafety and Biotechnology, Scientific Institute of Public Health, B-1050 Brussels, Belgium
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8
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Sapunaric FM, Levy SB. Second-site suppressor mutations for the serine 202 to phenylalanine substitution within the interdomain loop of the tetracycline efflux protein Tet(C). J Biol Chem 2003; 278:28588-92. [PMID: 12766164 DOI: 10.1074/jbc.m302658200] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The serine 202 to phenylalanine substitution within the cytoplasmic interdomain loop of Tet(C) greatly reduces tetracycline resistance and efflux activity (Saraceni-Richards, C. A., and Levy, S. B. (2000) J. Biol. Chem. 275, 6101-6106). Second-site suppressor mutations were identified following hydroxylamine and nitrosoguanidine mutagenesis. Three mutations, L11F in transmembrane 1 (TM1), A213T in the central interdomain loop, and A270V in cytoplasmic loop 8-9, restored a wild type level of resistance and an active efflux activity in Escherichia coli cells bearing the mutant tet(C) gene. The Tet S202F protein with the additional A270V mutation was expressed in amounts comparable with the original mutant, whereas L11F and A213T Tet(C) protein mutants were overexpressed. Introduction of each single mutation into the wild type tet(C) gene by site-directed mutagenesis did not alter tetracycline resistance or efflux activity. These secondary mutations may restore resistance by promoting a conformational change in the protein to accommodate the S202F mutation. The data demonstrate an interaction of the interdomain loop with other distant regions of the protein and support a role of the interdomain loop in mediating tetracycline resistance.
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Affiliation(s)
- Frederic M Sapunaric
- Center for Adaptation Genetics and Drug Resistance and the Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts 02111, USA
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9
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Persson BL, Lagerstedt JO, Pratt JR, Pattison-Granberg J, Lundh K, Shokrollahzadeh S, Lundh F. Regulation of phosphate acquisition in Saccharomyces cerevisiae. Curr Genet 2003; 43:225-44. [PMID: 12740714 DOI: 10.1007/s00294-003-0400-9] [Citation(s) in RCA: 118] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2003] [Revised: 04/05/2003] [Accepted: 04/08/2003] [Indexed: 01/08/2023]
Abstract
Membrane transport systems active in cellular inorganic phosphate (P(i)) acquisition play a key role in maintaining cellular P(i) homeostasis, independent of whether the cell is a unicellular microorganism or is contained in the tissue of a higher eukaryotic organism. Since unicellular eukaryotes such as yeast interact directly with the nutritious environment, regulation of P(i) transport is maintained solely by transduction of nutrient signals across the plasma membrane. The individual yeast cell thus recognizes nutrients that can act as both signals and sustenance. The present review provides an overview of P(i) acquisition via the plasma membrane P(i) transporters of Saccharomyces cerevisiae and the regulation of internal P(i) stores under the prevailing P(i) status.
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Affiliation(s)
- Bengt L Persson
- Department of Chemistry and Biomedical Science, Kalmar University, P.O. Box 905, 39182, Kalmar, Sweden.
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10
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Hirai T, Heymann JAW, Maloney PC, Subramaniam S. Structural model for 12-helix transporters belonging to the major facilitator superfamily. J Bacteriol 2003; 185:1712-8. [PMID: 12591890 PMCID: PMC148079 DOI: 10.1128/jb.185.5.1712-1718.2003] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The major facilitator superfamily includes a large collection of evolutionarily related proteins that have been implicated in the transport of a variety of solutes and metabolites across the membranes of organisms ranging from bacteria to humans. We have recently reported the three-dimensional structure, at 6.5 A resolution, of the oxalate transporter, OxlT, a representative member of this superfamily. In the oxalate-bound state, 12 helices surround a central cavity to form a remarkably symmetrical structure that displays a well-defined pseudo twofold axis perpendicular to the plane of the membrane as well as two less pronounced, mutually perpendicular pseudo twofold axes in the plane of the membrane. Here, we combined this structural information with sequence information from other members of this protein family to arrive at models for the arrangement of helices in this superfamily of transport proteins. Our analysis narrows down the number of helix arrangements from about a billion starting possibilities to a single probable model for the relative spatial arrangement for the 12 helices, consistent both with our structural findings and with the majority of previous biochemical studies on members of this superfamily.
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Affiliation(s)
- Teruhisa Hirai
- Laboratory of Biochemistry, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
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McMurry LM, Aldema-Ramos ML, Levy SB. Fe(2+)-tetracycline-mediated cleavage of the Tn10 tetracycline efflux protein TetA reveals a substrate binding site near glutamine 225 in transmembrane helix 7. J Bacteriol 2002; 184:5113-20. [PMID: 12193628 PMCID: PMC135328 DOI: 10.1128/jb.184.18.5113-5120.2002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
TetA specified by Tn10 is a class B member of a group of related bacterial transport proteins of 12 transmembrane alpha helices that mediate resistance to the antibiotic tetracycline. A tetracycline-divalent metal cation complex is expelled from the cell in exchange for a entering proton. The site(s) where tetracycline binds to this export pump is not known. We found that, when chelated to tetracycline, Fe(2+) cleaved the backbone of TetA predominantly at a single position, glutamine 225 in transmembrane helix 7. The related class D TetA protein from plasmid RA1 was cut at exactly the same position. There was no cleavage with glycylcycline, an analog of tetracycline that does not bind to TetA. The Fe(2+)-tetracycline complex was not detectably transported by TetA. However, cleavage products of the same size as with Fe(2+) occurred with Co(2+), known to be cotransported with tetracycline. The known substrate Mg (2+)-tetracycline interfered with cleavage by Fe(2+). These findings suggest that cleavage results from binding at a substrate-specific site. Fe(2+) is known to be able to cleave amide bonds in proteins at distances up to approximately 12 A. We conclude that the alpha carbon of glutamine 225 is probably within 12 A of the position of the Fe(2+) ion in the Fe(2+)-tetracycline complex bound to the protein.
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Affiliation(s)
- Laura M McMurry
- Center for Adaptation Genetics and Drug Resistance and Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts 02111, USA.
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12
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13
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Jin J, Guffanti AA, Beck C, Krulwich TA. Twelve-transmembrane-segment (TMS) version (DeltaTMS VII-VIII) of the 14-TMS Tet(L) antibiotic resistance protein retains monovalent cation transport modes but lacks tetracycline efflux capacity. J Bacteriol 2001; 183:2667-71. [PMID: 11274128 PMCID: PMC95185 DOI: 10.1128/jb.183.8.2667-2671.2001] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A "Tet(L)-12" version of Tet(L), a tetracycline efflux protein with 14 transmembrane segments (TMS), was constructed by deletion of two central TMS. Tet(L)-12 catalyzed Na+/H+ antiport and antiport with K+ as a coupling ion as well as or better than wild-type Tet(L) but exhibited no tetracycline-Me2+/H+ antiport in Escherichia coli vesicles.
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Affiliation(s)
- J Jin
- Department of Biochemistry and Molecular Biology, Mount Sinai School of Medicine, New York, New York 10029, USA
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14
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Perreten V, Schwarz FV, Teuber M, Levy SB. Mdt(A), a new efflux protein conferring multiple antibiotic resistance in Lactococcus lactis and Escherichia coli. Antimicrob Agents Chemother 2001; 45:1109-14. [PMID: 11257023 PMCID: PMC90432 DOI: 10.1128/aac.45.4.1109-1114.2001] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2000] [Accepted: 01/12/2001] [Indexed: 11/20/2022] Open
Abstract
The mdt(A) gene, previously designated mef214, from Lactococcus lactis subsp. lactis plasmid pK214 encodes a protein [Mdt(A) (multiple drug transporter)] with 12 putative transmembrane segments (TMS) that contain typical motifs conserved among the efflux proteins of the major facilitator superfamily. However, it also has two C-motifs (conserved in the fifth TMS of the antiporters) and a putative ATP-binding site. Expression of the cloned mdt(A) gene decreased susceptibility to macrolides, lincosamides, streptogramins, and tetracyclines in L. lactis and Escherichia coli, but not in Enterococcus faecalis or in Staphylococcus aureus. Glucose-dependent efflux of erythromycin and tetracycline was demonstrated in L. lactis and in E. coli.
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Affiliation(s)
- V Perreten
- Center for Adaptation Genetics and Drug Resistance, Tufts University School of Medicine, Boston, Massachusetts 02111, USA
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15
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Guan L, Nakae T. Identification of essential charged residues in transmembrane segments of the multidrug transporter MexB of Pseudomonas aeruginosa. J Bacteriol 2001; 183:1734-9. [PMID: 11160105 PMCID: PMC95059 DOI: 10.1128/jb.183.5.1734-1739.2001] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The MexABM efflux pump exports structurally diverse xenobiotics, utilizing the proton electrochemical gradient to confer drug resistance on Pseudomonas aeruginosa. The MexB subunit traverses the inner membrane 12 times and has two, two, and one charged residues in putative transmembrane segments 2 (TMS-2), TMS-4, and TMS-10, respectively. All five residues were mutated, and MexB function was evaluated by determining the MICs of antibiotics and fluorescent dye efflux. Replacement of Lys342 with Ala, Arg, or Glu and Glu346 with Ala, Gln, or Asp in TMS-2 did not have a discernible effect. Ala, Asn, or Lys substitution for Asp407 in TMS-4, which is well conserved, led to loss of activity. Moreover, a mutant with Glu in place of Asp407 exhibited only marginal function, suggesting that the length of the side chain at this position is important. The only replacements for Asp408 in TMS-4 or Lys939 in TMS-10 that exhibited significant function were Glu and Arg, respectively, suggesting that the native charge at these positions is required. In addition, double neutral mutants or mutants in which the charged residues Asp407 and Lys939 or Asp408 and Lys939 were interchanged completely lost function. An Asp408-->Glu/Lys939-->Arg mutant retained significant activity, while an Asp407-->Glu/Lys939-->Arg mutant exhibited only marginal function. An Asp407-->Glu/Asp408-->Glu double mutant also lost activity, but significant function was restored by replacing Lys939 with Arg (Asp407-->Glu/Asp408-->Glu/Lys939-->Arg). Taken as a whole, the findings indicate that Asp407, Asp408, and Lys939 are functionally important and raise the possibility that Asp407, Asp408, and Lys939 may form a charge network between TMS-4 and TMS-10 that is important for proton translocation and/or energy coupling.
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Affiliation(s)
- L Guan
- Department of Molecular Life Science, Tokai University School of Medicine, Isehara 259-1193, Japan
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16
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Abstract
Helical membrane protein folding and oligomerization can be usefully conceptualized as involving two energetically distinct stages-the formation and subsequent side-to-side association of independently stable transbilayer helices. The interactions of helices with the bilayer, with prosthetic groups, and with each other are examined in the context of recent evidence. We conclude that the two-stage concept remains useful as an approach to simplifying discussions of stability, as a framework for folding concepts, and as a basis for understanding membrane protein evolution.
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Affiliation(s)
- J L Popot
- Laboratoire de Physicochimie Moléculaire des Membranes Biologiques, Centre National de la Recherche Scientifique UPR 9052, Institut de Biologie Physico-Chimique, F-75005 Paris, France.
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17
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Putman M, van Veen HW, Konings WN. Molecular properties of bacterial multidrug transporters. Microbiol Mol Biol Rev 2000; 64:672-93. [PMID: 11104814 PMCID: PMC99009 DOI: 10.1128/mmbr.64.4.672-693.2000] [Citation(s) in RCA: 583] [Impact Index Per Article: 24.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
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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Affiliation(s)
- M Putman
- Department of Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, NL-9751 NN Haren, The Netherlands
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18
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Persson BL, Petersson J, Fristedt U, Weinander R, Berhe A, Pattison J. Phosphate permeases of Saccharomyces cerevisiae: structure, function and regulation. BIOCHIMICA ET BIOPHYSICA ACTA 1999; 1422:255-72. [PMID: 10548719 DOI: 10.1016/s0304-4157(99)00010-6] [Citation(s) in RCA: 71] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Affiliation(s)
- B L Persson
- Department of Engineering, Växjö University, S-351 95, Växjö, Sweden.
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van Veen HW, Konings WN. Structure and function of multidrug transporters. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1999; 456:145-58. [PMID: 10549367 DOI: 10.1007/978-1-4615-4897-3_8] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- H W van Veen
- Department of Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Haren, The Netherlands.
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20
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Jewell JE, Orwick J, Liu J, Miller KW. Functional importance and local environments of the cysteines in the tetracycline resistance protein encoded by plasmid pBR322. J Bacteriol 1999; 181:1689-93. [PMID: 10049405 PMCID: PMC93563 DOI: 10.1128/jb.181.5.1689-1693.1999] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The properties of the cysteines in the pBR322-encoded tetracycline resistance protein have been examined. Cysteines are important but not essential for tetracycline transport activity. None of the cysteines reacted with biotin maleimide, suggesting that they are shielded from the aqueous phase or reside in a negatively charged local environment.
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Affiliation(s)
- J E Jewell
- Department of Molecular Biology, University of Wyoming, Laramie, Wyoming 82071, USA
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21
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De Rossi E, Blokpoel MC, Cantoni R, Branzoni M, Riccardi G, Young DB, De Smet KA, Ciferri O. Molecular cloning and functional analysis of a novel tetracycline resistance determinant, tet(V), from Mycobacterium smegmatis. Antimicrob Agents Chemother 1998; 42:1931-7. [PMID: 9687386 PMCID: PMC105712 DOI: 10.1128/aac.42.8.1931] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/1997] [Accepted: 04/01/1998] [Indexed: 11/20/2022] Open
Abstract
The nucleotide sequence and mechanism of action of a tetracycline resistance gene from Mycobacterium smegmatis were determined. Analysis of a 2.2-kb sequence fragment showed the presence of one open reading frame, designated tet(V), encoding a 419-amino-acid protein (molecular weight, 44,610) with at least 10 transmembrane domains. A database search showed that the gene is homologous to membrane-associated antibiotic efflux pump proteins but not to any known tetracycline efflux pumps. The steady-state accumulation level of tetracycline by M. smegmatis harboring a plasmid carrying the tet(V) gene was about fourfold lower than that of the parental strain. Furthermore, the energy uncoupler carbonyl cyanide m-chlorophenylhydrazone blocked tetracycline efflux in deenergized cells. These results suggest that the tet(V) gene codes for a drug antiporter which uses the proton motive force for the active efflux of tetracycline. By primer-specific amplification the gene appears to be restricted to M. smegmatis and M. fortuitum.
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Affiliation(s)
- E De Rossi
- Department of Genetics and Microbiology, University of Pavia, 27100 Pavia, Italy
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22
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Abstract
The major facilitator superfamily (MFS) is one of the two largest families of membrane transporters found on Earth. It is present ubiquitously in bacteria, archaea, and eukarya and includes members that can function by solute uniport, solute/cation symport, solute/cation antiport and/or solute/solute antiport with inwardly and/or outwardly directed polarity. All homologous MFS protein sequences in the public databases as of January 1997 were identified on the basis of sequence similarity and shown to be homologous. Phylogenetic analyses revealed the occurrence of 17 distinct families within the MFS, each of which generally transports a single class of compounds. Compounds transported by MFS permeases include simple sugars, oligosaccharides, inositols, drugs, amino acids, nucleosides, organophosphate esters, Krebs cycle metabolites, and a large variety of organic and inorganic anions and cations. Protein members of some MFS families are found exclusively in bacteria or in eukaryotes, but others are found in bacteria, archaea, and eukaryotes. All permeases of the MFS possess either 12 or 14 putative or established transmembrane alpha-helical spanners, and evidence is presented substantiating the proposal that an internal tandem gene duplication event gave rise to a primordial MFS protein prior to divergence of the family members. All 17 families are shown to exhibit the common feature of a well-conserved motif present between transmembrane spanners 2 and 3. The analyses reported serve to characterize one of the largest and most diverse families of transport proteins found in living organisms.
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Affiliation(s)
- S S Pao
- Department of Biology, University of California at San Diego, La Jolla 92093-0116, USA
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23
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Abstract
Protein folding that is coupled to disulphide bond formation has many experimental advantages. In particular, the kinetic roles and importance of all the disulphide intermediates can be determined, usually unambiguously. This contrasts with other types of protein folding, where the roles of any intermediates detected are usually not established. Nevertheless, there is considerable confusion in the literature about even the best-characterized disulphide folding pathways. This article attempts to set the record straight.
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24
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Abstract
Multidrug efflux systems display the ability to transport a variety of structurally unrelated drugs from a cell and consequently are capable of conferring resistance to a diverse range of chemotherapeutic agents. This review examines multidrug efflux systems which use the proton motive force to drive drug transport. These proteins are likely to operate as multidrug/proton antiporters and have been identified in both prokaryotes and eukaryotes. Such proton-dependent multidrug efflux proteins belong to three distinct families or superfamilies of transport proteins: the major facilitator superfamily (MFS), the small multidrug resistance (SMR) family, and the resistance/ nodulation/cell division (RND) family. The MFS consists of symporters, antiporters, and uniporters with either 12 or 14 transmembrane-spanning segments (TMS), and we show that within the MFS, three separate families include various multidrug/proton antiport proteins. The SMR family consists of proteins with four TMS, and the multidrug efflux proteins within this family are the smallest known secondary transporters. The RND family consists of 12-TMS transport proteins and includes a number of multidrug efflux proteins with particularly broad substrate specificity. In gram-negative bacteria, some multidrug efflux systems require two auxiliary constituents, which might enable drug transport to occur across both membranes of the cell envelope. These auxiliary constituents belong to the membrane fusion protein and the outer membrane factor families, respectively. This review examines in detail each of the characterized proton-linked multidrug efflux systems. The molecular basis of the broad substrate specificity of these transporters is discussed. The surprisingly wide distribution of multidrug efflux systems and their multiplicity in single organisms, with Escherichia coli, for instance, possessing at least nine proton-dependent multidrug efflux systems with overlapping specificities, is examined. We also discuss whether the normal physiological role of the multidrug efflux systems is to protect the cell from toxic compounds or whether they fulfil primary functions unrelated to drug resistance and only efflux multiple drugs fortuitously or opportunistically.
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Affiliation(s)
- I T Paulsen
- School of Biological Sciences, University of Sydney, New South Wales, Australia
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25
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Chapter 8 Multidrug resistance in prokaryotes: Molecular mechanisms of drug efflux. ACTA ACUST UNITED AC 1996. [DOI: 10.1016/s1383-8121(96)80049-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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26
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Allen NE. Biochemical mechanisms of resistance to non-cell wall antibacterial agents. PROGRESS IN MEDICINAL CHEMISTRY 1995; 32:157-238. [PMID: 8577918 DOI: 10.1016/s0079-6468(08)70454-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Affiliation(s)
- N E Allen
- Infectious Disease Research, Eli Lilly and Company, Indianapolis, IN 46285, USA
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27
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Abstract
Recent experiments in bacterial systems have established an extended database of sequences broadly relevant to all membrane transporters, allowing serious study of evolutionary relationships. The database will be especially useful in integrating conclusions derived from work with proteins in the major facilitator superfamily, because this kinship includes both eukaryotic and prokaryotic model systems. Even among carriers not linked by evolution, clear hints of functional homology have been note. Advances are also evident in the structural analysis of membrane carriers. Site-directed mutagenesis in a bacterial antiporter has shown how the translocation pathway might be identified; this should complement recent progress in preparing two-dimensional crystals of the eukaryotic anion-exchange protein, band 3. Together, these studies could soon verify or reject the idea that the transport pathway lies at the interface between the amino-terminal and carboxy-terminal helical bundles found in the hydrophobic core of most carrier proteins. If verified, the argument might allow construction of informed three-dimensional models in the absence of crystallographic evidence.
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Affiliation(s)
- P C Maloney
- Department of Physiology, Johns Hopkins Medical School, Baltimore, MD 21205
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28
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Fani R, Liò P, Chiarelli I, Bazzicalupo M. The evolution of the histidine biosynthetic genes in prokaryotes: a common ancestor for the hisA and hisF genes. J Mol Evol 1994; 38:489-95. [PMID: 8028028 DOI: 10.1007/bf00178849] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The hisA and hisF genes belong to the histidine operon that has been extensively studied in the enterobacteria Escherichia coli and Salmonella typhimurium where the hisA gene codes for the phosphoribosyl-5-amino-1-phosphoribosyl-4-imidazolecarboxamide isomerase (EC 5.3.1.16) catalyzing the fourth step of the histidine biosynthetic pathway, and the hisF gene codes for a cyclase catalyzing the sixth reaction. Comparative analysis of nucleotide and predicted amino acid sequence of hisA and hisF genes in different microorganisms showed extensive sequence homology (43% considering similar amino acids), suggesting that the two genes arose from an ancestral gene by duplication and subsequent evolutionary divergence. A more detailed analysis, including mutual information, revealed an internal duplication both in hisA and hisF genes in each of the considered microorganisms. We propose that the hisA and hisF have originated from the duplication of a smaller ancestral gene corresponding to half the size of the actual genes followed by rapid evolutionary divergence. The involvement of gene elongation, gene duplication, and gene fusion in the evolution of the histidine biosynthetic genes is also discussed.
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Affiliation(s)
- R Fani
- Dipartimento di Biologia Animale e Genetica, Università degli Studi, Firenze, Italy
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29
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Abstract
Multidrug resistance pumps (MDRs) arise from three different gene families and are widespread in bacteria. For example, in Escherichia coli alone, there seem to be seven distinct MDRs. The most common belong to the major facilitator family of membrane translocases; this type of MDR is closely related to specific antibiotic extrusion pumps such as the tetracycline/H+ antiporter. This similarity in design, and the high incidence of apparently independent evolution of MDRs, suggests that the property of multidrug resistance might have resulted from a loss of specificity in a specific hydrophobic-drug efflux pump.
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Affiliation(s)
- K Lewis
- Department of Biology, Massachusetts Institute of Technology, Cambridge 02139
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30
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Sloan J, McMurry LM, Lyras D, Levy SB, Rood JI. The Clostridium perfringens Tet P determinant comprises two overlapping genes: tetA(P), which mediates active tetracycline efflux, and tetB(P), which is related to the ribosomal protection family of tetracycline-resistance determinants. Mol Microbiol 1994; 11:403-15. [PMID: 8170402 DOI: 10.1111/j.1365-2958.1994.tb00320.x] [Citation(s) in RCA: 82] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The complete nucleotide sequence and mechanism of action of the tetracycline-resistance determinant, Tet P, from Clostridium perfringens has been determined. Analysis of the 4.4 kb of sequence data revealed the presence of two open reading frames, designated as tetA(P) and tetB(P). The tetA(P) gene appears to encode a 420 amino acid protein (molecular weight 46,079) with twelve transmembrane domains. This gene was shown to be responsible for the active efflux of tetracycline from resistant cells. Although there was some amino acid sequence similarity between the putative TetA(P) protein and other tetracycline efflux proteins, analysis suggested that TetA(P) represented a different type of efflux protein. The tetB(P) gene would encode a putative 652 amino acid protein (molecular weight 72,639) with significant sequence similarity to Tet(M)-like cytoplasmic proteins that specify a ribosomal-protection tetracycline-resistance mechanism. In both C. perfringens and Escherichia coli, tetB(P) encoded low-level resistance to tetracycline and minocycline whereas tetA(P) only conferred tetracycline resistance. The tetA(P) and tetB(P) genes appeared to be linked in an operon, which represented a novel genetic arrangement for tetracycline-resistance determinants. It is proposed that tetB(P) evolved from the conjugative transfer into C. perfringens of a tet(M)-like gene from another bacterium.
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Affiliation(s)
- J Sloan
- Department of Microbiology, Monash University, Clayton, Australia
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31
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Yamaguchi A, O'yauchi R, Someya Y, Akasaka T, Sawai T. Second-site mutation of Ala-220 to Glu or Asp suppresses the mutation of Asp-285 to Asn in the transposon Tn10-encoded metal-tetracycline/H+ antiporter of Escherichia coli. J Biol Chem 1993. [DOI: 10.1016/s0021-9258(19)74208-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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32
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Allard JD, Bertrand KP. Sequence of a class E tetracycline resistance gene from Escherichia coli and comparison of related tetracycline efflux proteins. J Bacteriol 1993; 175:4554-60. [PMID: 8331085 PMCID: PMC204899 DOI: 10.1128/jb.175.14.4554-4560.1993] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
We determined the nucleotide sequence of the class E tetA gene on plasmid pSL1456 from Escherichia coli SLH1456A. The deduced amino acid sequence of the class E TetA protein shows 50 to 56% identity with the sequences of five related TetA proteins (classes A through D and G). Hydrophobicity profiles identify 12 putative transmembrane segments with similar boundaries in all six TetA sequences. The N-terminal alpha domain of the six sequences is more highly conserved than the C-terminal beta domain; the central hydrophilic loop connecting the alpha and beta domains is the least conserved region. Amino acid residues that have been shown to be important for class B (Tn10) TetA function are conserved in all six TetA sequences. Unlike the class B tetA gene, the class D and E tetA genes do not exhibit a negative gene dosage effect when present on multicopy plasmids derived from pACYC177.
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Affiliation(s)
- J D Allard
- Department of Microbiology, Washington State University, Pullman 99164
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33
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Yamaguchi A, Someya Y, Sawai T. The in vivo assembly and function of the N- and C-terminal halves of the Tn10-encoded TetA protein in Escherichia coli. FEBS Lett 1993; 324:131-5. [PMID: 8389718 DOI: 10.1016/0014-5793(93)81378-d] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The tetA gene was cut into its N- and C-terminal halves at the central EcoRI site and the two halves were subcloned individually or together under a separate lac promoter/operator. The expression of the C-terminal half was detected with a C-terminal-specific antibody. The amount of the N-terminal half in the cytoplasmic membrane was not affected by the presence of the C-terminal half. In contrast, the amount of the C-terminal half in the membrane was increased in the presence of the N-terminal half, indicating that the N-terminal half helps the stable folding of the C-terminal half in the membrane. Each half individually showed no tetracycline transport activity, however, when both halves were expressed together, the resultant complex showed about 40% of the tetracycline transport activity of the wild-type per number of the C-terminals of TetA protein in the membrane.
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Affiliation(s)
- A Yamaguchi
- Division of Microbial Chemistry, Faculty of Pharmaceutical Sciences, Chiba University, Japan
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34
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Yamaguchi A, Kimura T, Someya Y, Sawai T. Metal-tetracycline/H+ antiporter of Escherichia coli encoded by transposon Tn10. The structural resemblance and functional difference in the role of the duplicated sequence motif between hydrophobic segments 2 and 3 and segments 8 and 9. J Biol Chem 1993. [DOI: 10.1016/s0021-9258(18)53278-6] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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35
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Paulsen IT, Skurray RA. Topology, structure and evolution of two families of proteins involved in antibiotic and antiseptic resistance in eukaryotes and prokaryotes--an analysis. Gene 1993; 124:1-11. [PMID: 8440470 DOI: 10.1016/0378-1119(93)90755-r] [Citation(s) in RCA: 104] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Analysis of deduced amino acid sequences has demonstrated that the sequences of eukaryotic and prokaryotic proteins mediating resistance to antibiotics and antiseptics are highly related. Hydropathy analysis and alignment of conserved motifs revealed that these proteins can be divided into two separate families with either 12 or 14 transmembrane segments (TMS). Conserved motifs have been identified which are either characteristic for each family or conserved in both families. The conservation of these motifs suggested that they may be essential for the function of these proteins. Phylogenetic and structural analysis revealed that the two families may have evolved from a common ancestor with six TMS.
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Affiliation(s)
- I T Paulsen
- School of Biological Sciences, University of Sydney, NSW, Australia
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36
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McMurry LM, Stephan M, Levy SB. Decreased function of the class B tetracycline efflux protein Tet with mutations at aspartate 15, a putative intramembrane residue. J Bacteriol 1992; 174:6294-7. [PMID: 1328154 PMCID: PMC207700 DOI: 10.1128/jb.174.19.6294-6297.1992] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The aspartate 15 residue within the first predicted intramembrane helix of the tetracycline efflux protein Tet has been conserved in four tetracycline resistance determinants from gram-negative bacteria. Its replacement in class B Tet by tyrosine, histidine, or asparagine resulted in a 60 to 85% loss of tetracycline resistance and a similar loss of tetracycline-proton antiport. The tyrosine and histidine substitutions lowered the Vmax of the efflux system by some 90% but did not alter the Km. The asparagine substitution raised the Km over 13-fold, while the Vmax was equal to or greater than that of the wild type. Therefore, although the nature of its role is unclear, aspartate 15 is important for normal Tet function.
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Affiliation(s)
- L M McMurry
- Department of Molecular Biology, Tufts University School of Medicine, Boston, Massachusetts 02111
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37
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Yamaguchi A, Someya Y, Sawai T. Metal-tetracycline/H+ antiporter of Escherichia coli encoded by transposon Tn10. The role of a conserved sequence motif, GXXXXRXGRR, in a putative cytoplasmic loop between helices 2 and 3. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(18)41755-3] [Citation(s) in RCA: 74] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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38
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Allard J, Bertrand K. Membrane topology of the pBR322 tetracycline resistance protein. TetA-PhoA gene fusions and implications for the mechanism of TetA membrane insertion. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(19)37116-9] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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39
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Griffith JK, Baker ME, Rouch DA, Page MG, Skurray RA, Paulsen IT, Chater KF, Baldwin SA, Henderson PJ. Membrane transport proteins: implications of sequence comparisons. Curr Opin Cell Biol 1992; 4:684-95. [PMID: 1419050 DOI: 10.1016/0955-0674(92)90090-y] [Citation(s) in RCA: 258] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Analyses of the sequences and structures of many transport proteins that differ in substrate specificity, direction of transport and mechanism of transport suggest that they form a family of related proteins. Their sequence similarities imply a common mechanism of action. This hypothesis provides an objective basis for examining their mechanisms of action and relationships to other transporters.
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40
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Zhang HZ, Schmidt H, Piepersberg W. Molecular cloning and characterization of two lincomycin-resistance genes, lmrA and lmrB, from Streptomyces lincolnensis 78-11. Mol Microbiol 1992; 6:2147-57. [PMID: 1328813 DOI: 10.1111/j.1365-2958.1992.tb01388.x] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Two different lincomycin-resistance determinants (lmrA and lmrB) from Streptomyces lincolnensis 78-11 were cloned in Streptomyces lividans 66 TK23. The gene lmrA was localized on a 2.16 kb fragment, the determined nucleotide sequence of which encoded a single open reading frame 1446 bp long. Analysis of the deduced amino acid sequence suggested the presence of 12 membrane-spanning domains and showed significant similarities to the methylenomycin-resistance protein (Mmr) from Streptomyces coelicolor, the QacA protein from Staphylococcus aureus, and several tetracycline-resistance proteins from both Gram-positive and Gram-negative bacteria, as well as to some sugar-transport proteins from Escherichia coli. The lmrB gene was actively expressed from a 2.7 kb fragment. An open reading frame of 837 bp could be localized which encoded a protein that was significantly similar to 23S rRNA adenine(2058)-N-methyltransferases conferring macrolide-lincosamide-streptogramin resistance. LmrB also had putative rRNA methyltransferase activity since lincomycin resistance of ribosomes was induced in lmrB-containing strains. Surprisingly, both enzymes, LmrA and LmrB, had a substrate specificity restricted to lincomycin and did not cause resistance to other lincosamides such as celesticetin and clindamycin, or to macrolides.
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Affiliation(s)
- H Z Zhang
- Bergische Universität GH Wuppertal, Germany
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41
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Jones CS, Osborne DJ, Stanley J. Enterobacterial tetracycline resistance in relation to plasmid incompatibility. Mol Cell Probes 1992; 6:313-7. [PMID: 1528201 DOI: 10.1016/0890-8508(92)90007-k] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Sixty-eight well-characterized antibiotic resistance (R) plasmids belonging to 19 Incompatibility groups were screened with probes representing heterologous classes (A-E) of the enterobacterial tetracycline resistance (TcR) determinant. The Class B determinant was shown to be predominant in the IncF and IncH complexes and the IncC group. The Class A determinant was shown to be predominant in the IncP and IncM groups. There was no correlation between distribution of the class of TcR gene and the genus or the species of the host bacterial strain. The plasmids R714a (IncFI) and pHH1465 (IncC) contained TcR determinants which had no homology with any of these five probes.
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Affiliation(s)
- C S Jones
- Molecular Genetics Unit, Central Public Health Laboratory, London, UK
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42
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Yamaguchi A, Akasaka T, Ono N, Someya Y, Nakatani M, Sawai T. Metal-tetracycline/H+ antiporter of Escherichia coli encoded by transposon Tn10. Roles of the aspartyl residues located in the putative transmembrane helices. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(18)42544-6] [Citation(s) in RCA: 60] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
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43
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Affiliation(s)
- S B Levy
- Department of Molecular Biology, Tufts University School of Medicine, New England Medical Center, Boston, Massachusetts 02111
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44
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Abstract
There is a symbiotic relationship between the evolution of fundamental theory and the winning of experimentally-based knowledge. The impact of the General Chemiosmotic Theory on our understanding of the nature of membrane transport processes is described and discussed. The history of experimental studies on transport catalysed by ionophore antibiotics and the membrane proteins of mitochondria and bacteria are used to illustrate the evolution of knowledge and theory. Recent experimental approaches to understanding the lactose-H+ symport protein of Escherichia coli and other sugar porters are described to show that the lack of experimental knowledge of the three-dimensional structures of the proteins currently limits the development of theories about their molecular mechanism of translocation catalysis.
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45
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Rubin RA, Levy SB. Tet protein domains interact productively to mediate tetracycline resistance when present on separate polypeptides. J Bacteriol 1991; 173:4503-9. [PMID: 2066343 PMCID: PMC208114 DOI: 10.1128/jb.173.14.4503-4509.1991] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Both domains, alpha and beta, of the cytoplasmic membrane-localized Tet proteins encoded by the tet gene family (classes A through E) are required for resistance to tetracycline (Tcr) in gram-negative bacteria. Two inactive proteins, each containing a mutation in the opposite domain, are capable of complementation to produce Tcr. Similarly, inactive hybrid proteins expressed by interdomain gene hybrids constructed between tet(B) and tet(C) [tet(B) alpha/(C) beta and tet(C) alpha/(B) beta] together produce significant Tcr via trans complementation (R.A. Rubin and S. B. Levy, J. Bacteriol. 172:2303-2312, 1990). A derivative of tet(B) was constructed to express the two domains of Tet(B) as separate polypeptides, neither containing intact the central, hydrophilic interdomain region. Cells harboring this tet(B) mutant expressed Tcr at about 20% the level conferred by intact tet(B). As expected, no detectable amount of a full-length Tet protein was expressed. A polypeptide corresponding to the alpha domain was observed. Interdomain hybrids between tet(B) and tet(C) containing a frameshift at the fusion junction, designed to result in expression of each of the four domains on separate polypeptides, showed trans complementation without production of detectable full-length proteins. Levels of Tcr were greater than or equal to those previously observed in complementations using full-length hybrid proteins. These results strongly suggest that polypeptides harboring individual alpha and beta domains, lacking an intact interdomain region, can interact productively in the cell to confer Tcr.
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Affiliation(s)
- R A Rubin
- Department of Molecular Biology, Tufts University School of Medicine, Boston, Massachusetts
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46
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Metal-tetracycline/H+ antiporter of Escherichia coli encoded by a transposon Tn10. Histidine 257 plays an essential role in H+ translocation. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(18)38081-5] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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47
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Rubin RA, Levy SB. Interdomain hybrid Tet proteins confer tetracycline resistance only when they are derived from closely related members of the tet gene family. J Bacteriol 1990; 172:2303-12. [PMID: 2185211 PMCID: PMC208863 DOI: 10.1128/jb.172.5.2303-2312.1990] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Inner membrane Tet proteins encoded by tet genes in gram-negative bacteria mediate resistance to tetracycline (Tcr) by directing its export. Total sequences for class A, B, and C tet genes demonstrate that their products have a common ancestor, with Tet(A) and Tet(C) being more closely related (78% identical) than either is to Tet(B) (45% identical). The N- and C-terminal halves of Tet(B) and Tet(C) appear to comprise separate domains, and trans-complementation observed between tetracycline sensitive mutants in either domain of Tet(B) suggests separate but interactive functions for these domains. In this present study, interdomain hybrid genes were constructed to express hybrid tet products whose N- and C-terminal halves were derived from different family members [Tet(A/C), Tet(B/C), and Tet(C/B)]. Tet(A/C) specified a level of Tcr comparable to wild-type Tet(C) and 60% that of Tet(A), indicating that domains from these closely related tet products can function in cis. Although neither Tet(B/C) nor Tet(C/B) hybrids conferred significant Tcr, cells producing both of these types of hybrid proteins expressed substantial Tcr, indicating that productive interactions can occur in trans between Tet(B/C) and Tet(C/B). Taken together, these results suggest that highly specific interactions between the N- and C-terminal domains are necessary for Tcr and do not occur in individual hybrids derived from the more distant relatives, Tet(B) and Tet(C). This requirement for specific interactions suggests that N- and C-terminal domains have coevolved in each member of the Tet family.
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Affiliation(s)
- R A Rubin
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts 02111
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