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Das Q, Lepp D, Yin X, Ross K, McCallum JL, Warriner K, Marcone MF, Diarra MS. Transcriptional profiling of Salmonella enterica serovar Enteritidis exposed to ethanolic extract of organic cranberry pomace. PLoS One 2019; 14:e0219163. [PMID: 31269043 PMCID: PMC6608956 DOI: 10.1371/journal.pone.0219163] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Accepted: 06/17/2019] [Indexed: 11/19/2022] Open
Abstract
Non-typhoidal Salmonella enterica serovars continue to be an important food safety issue worldwide. Cranberry (Vaccinium macrocarpon Ait) fruits possess antimicrobial properties due to their various acids and phenolic compounds; however, the underlying mechanism of actions is poorly understood. We evaluated the effects of cranberry extracts on the growth rate of Salmonella enterica serovars Typhimurium, Enteritidis and Heidelberg and on the transcriptomic profile of Salmonella Enteritidis to gain insight into phenotypic and transcriptional changes induced by cranberry extracts on this pathogen. An ethanolic extract from cranberry pomaces (KCOH) and two of its sub-fractions, anthocyanins (CRFa20) and non-anthocyanin polyphenols (CRFp85), were used. The minimum inhibitory (MICs) and bactericidal (MBCs) concentrations of these fractions against tested pathogens were obtained using the broth micro-dilution method according to the Clinical Laboratory Standard Institute’s guidelines. Transcriptional profiles of S. Enteritidis grown in cation-adjusted Mueller-Hinton broth supplemented with or without 2 or 4 mg/ml of KCOH were compared by RNASeq to reveal gene modulations serving as markers for biological activity. The MIC and MBC values of KCOH were 8 and 16 mg/mL, respectively, against all tested S. enterica isolates. The MIC value was 4 mg/mL for both CRFa20 and CRFp85 sub-fractions, and a reduced MBC value was obtained for CRFp85 (4 mg/ml). Treatment of S. Enteritidis with KCOH revealed a concentration-dependent transcriptional signature. Compared to the control, 2 mg/ml of KCOH exposure resulted in 89 differentially expressed genes (DEGs), of which 53 and 36 were downregulated and upregulated, respectively. The upregulated genes included those involved in citrate metabolism, enterobactin synthesis and transport, and virulence. Exposure to 4 mg/ml KCOH led to the modulated expression of 376 genes, of which 233 were downregulated and 143 upregulated, which is 4.2 times more DEGs than from exposure to 2 mg/ml KCOH. The downregulated genes were related to flagellar motility, Salmonella Pathogenicity Island-1 (SPI-1), cell wall/membrane biogenesis, and transcription. Moreover, genes involved in energy production and conversion, carbohydrate transport and metabolism, and coenzyme transport and metabolism were upregulated during exposure to 4 mg/ml KCOH. Overall, 57 genes were differentially expressed (48 downregulated and 9 upregulated) in response to both concentrations. Both concentrations of KCOH downregulated expression of hilA, which is a major SPI-1 transcriptional regulator. This study provides information on the response of Salmonella exposed to cranberry extracts, which could be used in the control of this important foodborne pathogen.
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Affiliation(s)
- Quail Das
- Department of Food Science, University of Guelph, Ontario, Canada
- Guelph Research and Development Centre, Agriculture and Agri-Food Canada, Guelph, Ontario, Canada
| | - Dion Lepp
- Guelph Research and Development Centre, Agriculture and Agri-Food Canada, Guelph, Ontario, Canada
| | - Xianhua Yin
- Guelph Research and Development Centre, Agriculture and Agri-Food Canada, Guelph, Ontario, Canada
| | - Kelly Ross
- Summerland Research and Development Center, Agriculture and Agri-Food Canada, Summerland, British Columbia, Canada
| | - Jason L. McCallum
- Charlottetown Research and Development Center, Agriculture and Agri-Food Canada, Charlottetown, Prince Edward Island, Canada
| | - Keith Warriner
- Department of Food Science, University of Guelph, Ontario, Canada
| | | | - Moussa S. Diarra
- Guelph Research and Development Centre, Agriculture and Agri-Food Canada, Guelph, Ontario, Canada
- * E-mail:
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CitAB Two-Component System-Regulated Citrate Utilization Contributes to Vibrio cholerae Competitiveness with the Gut Microbiota. Infect Immun 2019; 87:IAI.00746-18. [PMID: 30559220 DOI: 10.1128/iai.00746-18] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2018] [Accepted: 12/09/2018] [Indexed: 01/05/2023] Open
Abstract
Citrate is a ubiquitous compound and can be utilized by many bacterial species, including enteric pathogens, as a carbon and energy source. Genes involved in citrate utilization have been extensively studied in some enteric bacteria, such as Klebsiella pneumoniae; however, their role in pathogenesis is still not clear. In this study, we investigated citrate utilization and regulation in Vibrio cholerae, the causative agent of cholera. The putative anaerobic citrate fermentation genes in V. cholerae, consisting of citCDEFXG, citS-oadGAB, and the two-component system (TCS) genes citAB, are highly homologous to those in K. pneumoniae Deletion analysis shows that these cit genes are essential for V. cholerae growth when citrate is the sole carbon source. The expression of citC and citS operons was dependent on citrate and CitAB, whose transcription was autorepressed and regulated by another TCS regulator, ArcA. In addition, citrate fermentation was under the control of catabolite repression. Mouse colonization experiments showed that V. cholerae can utilize citrate in vivo using the citrate fermentation pathway and that V. cholerae likely needs to compete with other members of the gut microbiota to access citrate in the gut.
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Abstract
Environmental citrate or malonate is degraded by a variety of aerobic or anaerobic bacteria. For selected examples, the genes encoding the specific enzymes of the degradation pathway are described together with the encoded proteins and their catalytic mechanisms. Aerobic bacteria degrade citrate readily by the basic enzyme equipment of the cell if a specific transporter for citrate is available. Anaerobic degradation of citrate in Klebsiella pneumoniae requires the so-called substrate activation module to convert citrate into its thioester with the phosphoribosyl dephospho-CoA prosthetic group of citrate lyase. The citryl thioester is subsequently cleaved into oxaloacetate and the acetyl thioester, from which a new citryl thioester is formed as the turnover continues. The degradation of malonate likewise includes a substrate activation module with a phosphoribosyl dephospho-CoA prosthetic group. The machinery gets ready for turnover after forming the acetyl thioester with the prosthetic group. The acetyl residue is then exchanged by a malonyl residue, which is easily decarboxylated with the regeneration of the acetyl thioester. This equipment suffices for aerobic growth on malonate, since ATP is produced via the oxidation of acetate. Anaerobic growth on citrate or malonate, however, depends on additional enzymes of a so-called energy conservation module. This allows the conversion of decarboxylation energy into an electrochemical gradient of Na+ ions. In citrate-fermenting K. pneumoniae, the Na+ gradient is formed by the oxaloacetate decarboxylase and mainly used to drive the active transport of citrate into the cell. To use this energy source for this purpose is possible, since ATP is generated by substrate phosphorylation in the well-known sequence from pyruvate to acetate. In the malonate-fermenting bacterium Malonomonas rubra, however, no reactions for substrate level phosphorylation are available and the Na+ gradient formed in the malonate decarboxylation reaction must therefore be used as the driving force for ATP synthesis.
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Artificial citrate operon and Vitreoscilla hemoglobin gene enhanced mineral phosphate solubilizing ability of Enterobacter hormaechei DHRSS. Appl Microbiol Biotechnol 2014; 98:8327-36. [DOI: 10.1007/s00253-014-5912-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2014] [Revised: 05/29/2014] [Accepted: 06/24/2014] [Indexed: 10/25/2022]
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Lensbouer JJ, Li QW, Estlinbaum M, Doyle RP. R161, K452 and R460 residues are vital for metal–citrate complex transport in CitSc from Streptomyces coelicolor. Metallomics 2010; 2:342-7. [DOI: 10.1039/b920689b] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Sobczak I, Lolkema JS. The 2-hydroxycarboxylate transporter family: physiology, structure, and mechanism. Microbiol Mol Biol Rev 2006; 69:665-95. [PMID: 16339740 PMCID: PMC1306803 DOI: 10.1128/mmbr.69.4.665-695.2005] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The 2-hydroxycarboxylate transporter family is a family of secondary transporters found exclusively in the bacterial kingdom. They function in the metabolism of the di- and tricarboxylates malate and citrate, mostly in fermentative pathways involving decarboxylation of malate or oxaloacetate. These pathways are found in the class Bacillales of the low-CG gram-positive bacteria and in the gamma subdivision of the Proteobacteria. The pathways have evolved into a remarkable diversity in terms of the combinations of enzymes and transporters that built the pathways and of energy conservation mechanisms. The transporter family includes H+ and Na+ symporters and precursor/product exchangers. The proteins consist of a bundle of 11 transmembrane helices formed from two homologous domains containing five transmembrane segments each, plus one additional segment at the N terminus. The two domains have opposite orientations in the membrane and contain a pore-loop or reentrant loop structure between the fourth and fifth transmembrane segments. The two pore-loops enter the membrane from opposite sides and are believed to be part of the translocation site. The binding site is located asymmetrically in the membrane, close to the interface of membrane and cytoplasm. The binding site in the translocation pore is believed to be alternatively exposed to the internal and external media. The proposed structure of the 2HCT transporters is different from any known structure of a membrane protein and represents a new structural class of secondary transporters.
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Affiliation(s)
- Iwona Sobczak
- Molecular Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Kerklaan 30, 9751 NN Haren, The Netherlands
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Bandell M, Ansanay V, Rachidi N, Dequin S, Lolkema JS. Membrane potential-generating malate (MleP) and citrate (CitP) transporters of lactic acid bacteria are homologous proteins. Substrate specificity of the 2-hydroxycarboxylate transporter family. J Biol Chem 1997; 272:18140-6. [PMID: 9218448 DOI: 10.1074/jbc.272.29.18140] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Membrane potential generation via malate/lactate exchange catalyzed by the malate carrier (MleP) of Lactococcus lactis, together with the generation of a pH gradient via decarboxylation of malate to lactate in the cytoplasm, is a typical example of a secondary proton motive force-generating system. The mleP gene was cloned, sequenced, and expressed in a malolactic fermentation-deficient L. lactis strain. Functional analysis revealed the same properties as observed in membrane vesicles of a malolactic fermentation-positive strain. MleP belongs to a family of secondary transporters in which the citrate carriers from Leuconostoc mesenteroides (CitP) and Klebsiella pneumoniae (CitS) are found also. CitP, but not CitS, is also involved in membrane potential generation via electrogenic citrate/lactate exchange. MleP, CitP, and CitS were analyzed for their substrate specificity. The 2-hydroxycarboxylate motif R1R2COHCOOH, common to the physiological substrates, was found to be essential for transport although some 2-oxocarboxylates could be transported to a lesser extent. Clear differences in substrate specificity among the transporters were observed because of different tolerances toward the R substituents at the C2 atom. Both MleP and CitP transport a broad range of 2-hydroxycarboxylates with R substituents ranging in size from two hydrogen atoms (glycolate) to acetyl and methyl groups (citromalate) for MleP and two acetyl groups (citrate) for CitP. CitS was much less tolerant and transported only citrate and at a low rate citromalate. The substrate specificities are discussed in the context of the physiological function of the transporters.
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Affiliation(s)
- M Bandell
- Department of Microbiology, Groningen Biotechnology and Biomolecular Sciences Institute, University of Groningen, 9751NN Haren, The Netherlands
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8
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Kawai S, Suzuki H, Yamamoto K, Kumagai H. Characterization of the L-malate permease gene (maeP) of Streptococcus bovis ATCC 15352. J Bacteriol 1997; 179:4056-60. [PMID: 9190827 PMCID: PMC179220 DOI: 10.1128/jb.179.12.4056-4060.1997] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
A gene which was shown to be cotranscribed with the NAD+-dependent malic enzyme gene (maeE) of Streptococcus bovis ATCC 15352 was revealed to encode L-malate-specific permease (MaeP), which showed high activity at low pHs (pH 5.1 to 5.9). MaeP was strongly inhibited by the ionophores nigericin and valinomycin.
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Affiliation(s)
- S Kawai
- Department of Food Science and Technology, Faculty of Agriculture, Kyoto University, Sakyo-ku, Japan
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9
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Boorsma A, van der Rest ME, Lolkema JS, Konings WN. Secondary transporters for citrate and the Mg(2+)-citrate complex in Bacillus subtilis are homologous proteins. J Bacteriol 1996; 178:6216-22. [PMID: 8892821 PMCID: PMC178492 DOI: 10.1128/jb.178.21.6216-6222.1996] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Citrate uptake in Bacillus subtilis is mediated by a secondary transporter that transports the complex of citrate and divalent metal ions. The gene coding for the transporter termed CitM was cloned, sequenced, and functionally expressed in Escherichia coli. Translation of the base sequence to the primary sequence revealed a transporter that is not homologous to any known secondary transporter. However, CitM shares 60% sequence identity with the gene product of open reading frame N15CR that is on the genome of B. subtilis and for which no function is known. The hydropathy profiles of the primary sequences of CitM and the unknown gene product are very similar, and secondary structure prediction algorithms predict 12 transmembrane-spanning segments for both proteins. Open reading frame N15CR was cloned and expressed in E. coli and was shown to be a citrate transporter as well. The transporter is termed CitH. A remarkable difference between the two transporters is that citrate uptake by CitM is stimulated by the presence of Mg2+ ions, while citrate uptake by CitH is inhibited by Mg2+. It is concluded that the substrate of CitM is the Mg(2+)-citrate complex and that CitH transports the free citrate anion. Uptake experiments in right-side-out membrane vesicles derived from E. coli cells expressing either CitM or CitH showed that both transporters catalyze electrogenic proton/substrate symport.
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Affiliation(s)
- A Boorsma
- Department of Microbiology, Groningen Biotechnology and Biomolecular Sciences Institute, University of Groningen, The Netherlands
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Marty-Teysset C, Lolkema JS, Schmitt P, Divies C, Konings WN. Membrane potential-generating transport of citrate and malate catalyzed by CitP of Leuconostoc mesenteroides. J Biol Chem 1995; 270:25370-6. [PMID: 7592702 DOI: 10.1074/jbc.270.43.25370] [Citation(s) in RCA: 56] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Citrate uptake in Leuconostoc mesenteroides subsp. mesenteroides 19D is catalyzed by a secondary citrate carrier (CitP). The kinetics and mechanism of CitP were investigated in membrane vesicles of L. mesenteroides. The transporter is induced by the presence of citrate in the medium and transports both citrate and malate. In spite of sequence homology to the Na(+)-dependent citrate carrier of Klebsiella pneumoniae, CitP is not Na(+)-dependent, nor is CitP Mg(2+)-dependent. The pH gradient (delta pH) is a driving force for citrate and malate uptake into the membrane vesicles, whereas the membrane potential (delta psi) counteracts transport. An inverted membrane potential (inside positive) generated by thiocyanide diffusion can drive citrate and malate uptake in membrane vesicles. Analysis of the forces involved showed that a single unit of negative charge is translocated during transport. Kinetic analysis of citrate counterflow at different pH values indicated that CitP transports the dianionic form of citrate (Hcit2-) with an affinity constant of approximately 20 microns. It is concluded that CitP catalyzes Hcit2-/H+ symport. Translocation of negative charge into the cell during citrate metabolism results in the generation of a membrane potential that contributes to the protonmotive force across the cytoplasmic membrane, i.e. citrate metabolism in L. mesenteroides generates metabolic energy. Efficient exchange of citrate and D-lactate, a product of citrate/carbohydrate co-metabolism, is observed, suggesting that under physiological conditions, CitP may function as an electrogenic precursor/product exchanger rather than a symporter. The mechanism and energetic consequences of citrate uptake are similar to malate uptake in lactic acid bacteria.
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Affiliation(s)
- C Marty-Teysset
- Department of Microbiology, Groningen Biotechnology and Biomolecular Sciences Institute, University of Groningen, Haren, The Netherlands
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Vaughan EE, David S, Harrington A, Daly C, Fitzgerald GF, De Vos WM. Characterization of plasmid-encoded citrate permease (citP) genes from Leuconostoc species reveals high sequence conservation with the Lactococcus lactis citP gene. Appl Environ Microbiol 1995; 61:3172-6. [PMID: 7487049 PMCID: PMC167593 DOI: 10.1128/aem.61.8.3172-3176.1995] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
The citrate permease determinant (citP) in several Leuconostoc strains was demonstrated to be plasmid encoded by curing experiments and hybridization studies with a DNA fragment containing the citP gene from Lactococcus lactis subsp. lactis biovar diacetylactis NCDO176. Cloning and nucleotide sequence analysis of Leuconostoc lactis NZ6070 citP revealed almost complete identity to lactococcal citP.
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Affiliation(s)
- E E Vaughan
- Department of Biophysical Chemistry, Netherlands Institute for Dairy Research (NIZO), Ede
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López de Felipe F, Magni C, de Mendoza D, López P. Citrate utilization gene cluster of the Lactococcus lactis biovar diacetylactis: organization and regulation of expression. MOLECULAR & GENERAL GENETICS : MGG 1995; 246:590-9. [PMID: 7535377 DOI: 10.1007/bf00298965] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The transport of citrate in Lactococcus lactis biovar diacetylactis is mediated by the citrate permease P. This polypeptide is encoded by the citP gene carried by plasmid pCIT264. In this report, we characterize the citP transcript, identify a cluster of two genes cotranscribed with citP and describe their post-transcriptional regulation. The transcriptional promoter is located 1500 nucleotides upstream of the citP gene and the transcriptional terminator is positioned next to the 3'-end of this gene. The DNA sequence was determined of the region upstream of the citP gene, including the promoter. Two partially overlapping open reading frames, citQ and citR were identified, which could encode polypeptides of 3.9 and 13 kDa respectively. These two genes, together with citP, constitute the cit cluster. Moreover, an IS-like element located between the cit promoter and the citQ open reading frame was identified. This element includes an open reading frame ORF1, which could encode a 33 kDa polypeptide. A translational fusion between the citP and a cat reporter gene showed that translation of citR and citP is coupled, and regulated by CitR. The cit mRNA was subjected to specific cleavage after addition of rifampicin to the bacterial cultures. We propose that expression of the cit cluster is controlled at the post-transcriptional level by mRNA processing at a putative complex secondary structure and by translational repression mediated by CitR.
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MESH Headings
- Amino Acid Sequence
- Bacterial Proteins
- Base Sequence
- Carrier Proteins
- Citrates/metabolism
- Citric Acid
- DNA Transposable Elements/genetics
- Gene Expression Regulation, Bacterial/genetics
- Genes, Bacterial/genetics
- Lactococcus lactis/genetics
- Lactococcus lactis/metabolism
- Lactoferrin/genetics
- Membrane Transport Proteins/genetics
- Molecular Sequence Data
- Multigene Family/genetics
- Nucleic Acid Conformation
- Open Reading Frames/genetics
- Organic Anion Transporters
- Peptide Fragments/genetics
- Promoter Regions, Genetic/genetics
- Protein Biosynthesis/genetics
- RNA Processing, Post-Transcriptional/genetics
- RNA, Bacterial/chemistry
- RNA, Bacterial/genetics
- RNA, Messenger/chemistry
- RNA, Messenger/genetics
- Recombinant Fusion Proteins
- Sequence Analysis, DNA
- Terminator Regions, Genetic/genetics
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Affiliation(s)
- F López de Felipe
- Centro de Investigaciones Biológicas, C.S.I.C., Velázquez, Madrid, Spain
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Woehlke G, Dimroth P. Anaerobic growth of Salmonella typhimurium on L(+)- and D(-)-tartrate involves an oxaloacetate decarboxylase Na+ pump. Arch Microbiol 1994; 162:233-7. [PMID: 7802542 DOI: 10.1007/bf00301843] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
We show here that the Enterobacterium Salmonella typhimurium LT2 has the capacity to grow anaerobically on L(+)- or D(-)-tartrate as sole carbon and energy source. Growth on these substrates was Na(+)-dependent and involved the L(+)- or D(-)-tartrate-inducible expression of oxaloacetate decarboxylase. The induced decarboxylase was closely related to the oxaloacetate decarboxylase Na+ pump of Klebsiella pneumoniae as shown by the sensitivity towards avidin, the location in the cytoplasmic membrane, activation by Na+ ions, and Western blot analysis with antiserum raised against the K. pneumoniae oxaloacetate decarboxylase. Participation of an oxaloacetate decarboxylase Na+ pump in L(+)-tartrate degradation by S. typhimurium is in accord with results from DNA analyses. The deduced protein sequence of the open reading frame identified upstream of the recently sequenced oxaloacetate decarboxylase genes is clearly homologous with the beta-subunit of L-tartrate dehydratase from Escherichia coli. Southern blot analysis with S. typhimurium chromosomal DNA indicated the presence of probably more than one gene for oxaloacetate decarboxylase.
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Reizer J, Reizer A, Saier MH. A functional superfamily of sodium/solute symporters. BIOCHIMICA ET BIOPHYSICA ACTA 1994; 1197:133-66. [PMID: 8031825 DOI: 10.1016/0304-4157(94)90003-5] [Citation(s) in RCA: 179] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Eleven families of sodium/solute symporters are defined based on their degrees of sequence similarities, and the protein members of these families are characterized in terms of their solute and cation specificities, their sizes, their topological features, their evolutionary relationships, and their relative degrees and regions of sequence conservation. In some cases, particularly where site-specific mutagenesis analyses have provided functional information about specific proteins, multiple alignments of members of the relevant families are presented, and the degrees of conservation of the mutated residues are evaluated. Signature sequences for several of the eleven families are presented to facilitate identification of new members of these families as they become sequenced. Phylogenetic tree construction reveals the evolutionary relationships between members of each family. One of these families is shown to belong to the previously defined major facilitator superfamily. The other ten families do not show sufficient sequence similarity with each other or with other identified transport protein families to establish homology between them. This study serves to clarify structural, functional and evolutionary relationships among eleven distinct families of functionally related transport proteins.
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Affiliation(s)
- J Reizer
- Department of Biology, University of California at San Diego, La Jolla 92093-0116
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Liu SL, Hessel A, Sanderson KE. The XbaI-BlnI-CeuI genomic cleavage map of Salmonella enteritidis shows an inversion relative to Salmonella typhimurium LT2. Mol Microbiol 1993; 10:655-64. [PMID: 7968542 DOI: 10.1111/j.1365-2958.1993.tb00937.x] [Citation(s) in RCA: 54] [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
We have established the genomic cleavage map of Salmonella enteritidis strain SSU7998 using pulsed-field gel electrophoresis. The chromosome of 4600 kb was analysed by XbaI (16 fragments), I-CeuI (7 fragments) and BlnI (12 fragments); the genome also contains a plasmid of 60 kb. Cleavage sites of I-Ceul, in the large subunit ribosomal RNA gene, are conserved from Salmonella typhimurium and Escherichia coli K-12, and the XbaI and BlnI sites in glt-tRNA are also conserved, but other sites are less conserved. Transposon Tn10, located at 60 different positions in the chromosome of S. typhimurium, was transduced by bacteriophage P22 into S. enteritidis and the insertion mapped using the XbaI and BlnI sites on Tn10. Gene order in S. enteritidis is identical to S. typhimurium LT2 and similar to E. coli K-12 except for an inversion of 815 kb, which covers the terminus region including T1 and T2. Endpoints are in the NDZs, or non-divisible zones, in which inversion endpoints were not detected in experiments in E. coli K-12 and S. typhimurium LT2. This inversion resembles the inversion between S. typhimurium and E. coli, but is longer at both ends.
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Affiliation(s)
- S L Liu
- Department of Biological Sciences, University of Calgary, Alberta, Canada
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