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Silva LP, Yu R, Calmettes C, Yang X, Moraes TF, Schryvers AB, Schriemer DC. Conserved interaction between transferrin and transferrin-binding proteins from porcine pathogens. J Biol Chem 2011; 286:21353-60. [PMID: 21487007 DOI: 10.1074/jbc.m111.226449] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Gram-negative porcine pathogens from the Pasteurellaceae family possess a surface receptor complex capable of acquiring iron from porcine transferrin (pTf). This receptor consists of transferrin-binding protein A (TbpA), a transmembrane iron transporter, and TbpB, a surface-exposed lipoprotein. Questions remain as to how the receptor complex engages pTf in such a way that iron is positioned for release, and whether divergent strains present distinct recognition sites on Tf. In this study, the TbpB-pTf interface was mapped using a combination of mass shift analysis and molecular docking simulations, localizing binding uniquely to the pTf C lobe for multiple divergent strains of Actinobacillus plueropneumoniae and suis. The interface was further characterized and validated with site-directed mutagenesis. Although targeting a common lobe, variants differ in preference for the two sublobes comprising the iron coordination site. Sublobes C1 and C2 participate in high affinity binding, but sublobe C1 contributes in a minor fashion to the overall affinity. Further, the TbpB-pTf complex does not release iron independent of other mediators, based on competitive iron binding studies. Together, our findings support a model whereby TbpB efficiently captures and presents iron-loaded pTf to other elements of the uptake pathway, even under low iron conditions.
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Affiliation(s)
- Leslie P Silva
- Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, Alberta T2N 1N4, Canada
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52
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The role of vicinal tyrosine residues in the function of Haemophilus influenzae ferric-binding protein A. Biochem J 2010; 432:57-64. [DOI: 10.1042/bj20101043] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The periplasmic FbpA (ferric-binding protein A) from Haemophilus influenzae plays a critical role in acquiring iron from host transferrin, shuttling iron from the outer-membrane receptor complex to the inner-membrane transport complex responsible for transporting iron into the cytoplasm. In the present study, we report on the properties of a series of site-directed mutants of two adjacent tyrosine residues involved in iron co-ordination, and demonstrate that, in contrast with mutation of equivalent residues in the N-lobe of human transferrin, the mutant FbpAs retain significant iron-binding affinity regardless of the nature of the replacement amino acid. The Y195A and Y196A FbpAs are not only capable of binding iron, but are proficient in mediating periplasm-to-cytoplasm iron transport in a reconstituted FbpABC pathway in a specialized Escherichia coli reporter strain. This indicates that their inability to mediate iron acquisition from transferrin is due to their inability to compete for iron with receptor-bound transferrin. Wild-type iron-loaded FbpA could be crystalized in a closed or open state depending upon the crystallization conditions. The synergistic phosphate anion was not present in the iron-loaded open form, suggesting that initial anchoring of iron was mediated by the adjacent tyrosine residues and that alternate pathways for iron and anion binding and release may be considered. Collectively, these results demonstrate that the presence of a twin-tyrosine motif common to many periplasmic iron-binding proteins is critical for initially capturing the ferric ion released by the outer-membrane receptor complex.
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Role of Nitrosomonas europaea NitABC iron transporter in the uptake of Fe3+-siderophore complexes. Arch Microbiol 2010; 192:899-908. [DOI: 10.1007/s00203-010-0620-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2010] [Revised: 07/12/2010] [Accepted: 08/11/2010] [Indexed: 10/19/2022]
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Vallet-Gely I, Opota O, Boniface A, Novikov A, Lemaitre B. A secondary metabolite acting as a signalling molecule controls Pseudomonas entomophila virulence. Cell Microbiol 2010; 12:1666-79. [PMID: 20597908 DOI: 10.1111/j.1462-5822.2010.01501.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Pseudomonas entomophila is an entomopathogenic bacterium that is lethal to Drosophila melanogaster within 1-2 days of ingestion of high doses. Flies orally infected with P. entomophila rapidly succumb despite the induction of both local and systemic immune responses. Recent studies suggest that its virulence relies on its ability to cause irreversible damages to the intestinal epithelium, in contrast to what is observed with milder pathogenic bacteria such as Erwinia carotovora carotovora Ecc15 or Pseudomonas aeruginosa PA14. The GacS/GacA two-component system plays a key role in P. entomophila pathogenicity. Here, we report the identification of the pvf genes, whose products are involved in production of a secondary metabolite involved in P. entomophila virulence. A pvf mutant is impaired in its ability to persist within the gut, to trigger the fly immune responses and to inflict gut damages. The expression of several genes is affected in a pvf mutant, independently of the Gac system. Moreover, growing a pvf mutant in medium supplemented with supernatant extracts from either the wild-type strain or a gacA mutant restore its pathogenicity. Collectively, our results indicate that we identified genes involved in the synthesis of a signalling molecule that controls P. entomophila virulence independently from the Gac system.
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Henderson B, Ward JM, Ready D. Aggregatibacter (Actinobacillus) actinomycetemcomitans: a triple A* periodontopathogen? Periodontol 2000 2010; 54:78-105. [DOI: 10.1111/j.1600-0757.2009.00331.x] [Citation(s) in RCA: 145] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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56
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Zola TA, Strange HR, Dominguez NM, Dillard JP, Cornelissen CN. Type IV secretion machinery promotes ton-independent intracellular survival of Neisseria gonorrhoeae within cervical epithelial cells. Infect Immun 2010; 78:2429-37. [PMID: 20308306 PMCID: PMC2876539 DOI: 10.1128/iai.00228-10] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2010] [Revised: 02/22/2010] [Accepted: 03/09/2010] [Indexed: 01/18/2023] Open
Abstract
Survival of Neisseria gonorrhoeae within host epithelial cells is expected to be important in the pathogenesis of gonococcal disease. We previously demonstrated that strain FA1090 derives iron from a host cell in a process that requires the Ton complex and a putative TonB-dependent transporter, TdfF. FA1090, however, lacks the gonococcal genetic island (GGI) that is present in the majority of strains. The GGI in strain MS11 has been partially characterized, and it encodes a type IV secretion system (T4SS) involved in DNA release. In this study we investigated the role of iron acquisition and GGI-encoded gene products in gonococcal survival within cervical epithelial cells. We demonstrated that intracellular survival of MS11 was dependent on acquisition of iron from the host cell, but unlike the findings for FA1090, expression of the Ton complex was not required. Survival was not dependent on a putative TonB-like protein encoded in the GGI but instead was directly linked to T4SS structural components in a manner independent of the ability to release or internalize DNA. These data suggest that expression of selected GGI-encoded open reading frames confers an advantage during cervical cell infection. This study provides the first link between expression of the T4SS apparatus and intracellular survival of gonococci.
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Affiliation(s)
- Tracey A. Zola
- Department of Microbiology and Immunology, Medical College of Virginia Campus, Virginia Commonwealth University, Richmond, Virginia 23298, Department of Medical Microbiology and Immunology, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin 53706
| | - Heather R. Strange
- Department of Microbiology and Immunology, Medical College of Virginia Campus, Virginia Commonwealth University, Richmond, Virginia 23298, Department of Medical Microbiology and Immunology, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin 53706
| | - Nadia M. Dominguez
- Department of Microbiology and Immunology, Medical College of Virginia Campus, Virginia Commonwealth University, Richmond, Virginia 23298, Department of Medical Microbiology and Immunology, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin 53706
| | - Joseph P. Dillard
- Department of Microbiology and Immunology, Medical College of Virginia Campus, Virginia Commonwealth University, Richmond, Virginia 23298, Department of Medical Microbiology and Immunology, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin 53706
| | - Cynthia N. Cornelissen
- Department of Microbiology and Immunology, Medical College of Virginia Campus, Virginia Commonwealth University, Richmond, Virginia 23298, Department of Medical Microbiology and Immunology, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin 53706
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Biofilm formation by the human pathogen Neisseria meningitidis. Med Microbiol Immunol 2010; 199:173-83. [PMID: 20376486 DOI: 10.1007/s00430-010-0149-y] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2010] [Indexed: 10/19/2022]
Abstract
The past decade has seen an increasing interest in biofilm formation by Neisseria meningitidis, a human facultative pathogen causing life-threatening childhood disease commencing from asymptomatic nasopharyngeal colonization. Studying the biology of in vitro biofilm formation improves the understanding of inter-bacterial processes in asymptomatic carriage, of bacterial aggregate formation on host cells, and of meningococcal population biology. This paper reviews publications referring to meningococcal biofilm formation with an emphasis on the role of motility and of extracellular DNA. The theory of sub-dividing the meningococcal population in settler and spreader lineages is discussed, which provides a mechanistic framework for the assumed balance of colonization efficacy and transmission frequency.
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58
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Beddek AJ, Schryvers AB. The lactoferrin receptor complex in gram negative bacteria. Biometals 2010; 23:377-86. [DOI: 10.1007/s10534-010-9299-z] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2010] [Accepted: 01/29/2010] [Indexed: 10/19/2022]
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Regulatory role of the MisR/S two-component system in hemoglobin utilization in Neisseria meningitidis. Infect Immun 2009; 78:1109-22. [PMID: 20008531 DOI: 10.1128/iai.00363-09] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Outer membrane iron receptors are some of the major surface entities that are critical for meningococcal pathogenesis. The gene encoding the meningococcal hemoglobin receptor, HmbR, is both independently transcribed and transcriptionally linked to the upstream gene hemO, which encodes a heme oxygenase. The MisR/S two-component system was previously determined to regulate hmbR transcription, and its hemO and hmbR regulatory mechanisms were characterized further here. The expression of hemO and hmbR was downregulated in misR/S mutants under both iron-replete and iron-restricted conditions, and the downregulation could be reversed by complementation. No significant changes in expression of other iron receptors were detected, suggesting that the MisR/S system specifically regulates hmbR. When hemoglobin was the sole iron source, growth defects were detected in the mutants. Primer extension analysis identified a promoter upstream of the hemO-associated Correia element (CE) and another promoter at the proximal end of CE, and processed transcripts previously identified for other cotranscribed CEs were also detected, suggesting that there may be posttranscriptional regulation. MisR directly interacts with sequences upstream of the CE and upstream of the hmbR Fur binding site and thus independently regulates hemO and hmbR. Analysis of transcriptional reporters of hemO and hmbR further demonstrated the positive role of the MisR/S system and showed that the transcription of hmbR initiated from hemO was significantly reduced. A comparison of the effects of the misS mutation under iron-replete and iron-depleted conditions suggested that activation by the MisR/S system and iron-mediated repression by Fur act independently. Thus, the expression of hemO and hmbR is coordinately controlled by multiple independent regulatory mechanisms, including the MisR/S two-component system.
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60
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Molecular aspects of Moraxella catarrhalis pathogenesis. Microbiol Mol Biol Rev 2009; 73:389-406, Table of Contents. [PMID: 19721084 DOI: 10.1128/mmbr.00007-09] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
In recent years, Moraxella catarrhalis has established its position as an important human mucosal pathogen, no longer being regarded as just a commensal bacterium. Further, current research in the field has led to a better understanding of the molecular mechanisms involved in M. catarrhalis pathogenesis, including mechanisms associated with cellular adherence, target cell invasion, modulation of the host's immune response, and metabolism. Additionally, in order to be successful in the host, M. catarrhalis has to be able to interact and compete with the commensal flora and overcome stressful environmental conditions, such as nutrient limitation. In this review, we provide a timely overview of the current understanding of the molecular mechanisms associated with M. catarrhalis virulence and pathogenesis.
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61
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Ma Z, Jacobsen FE, Giedroc DP. Coordination chemistry of bacterial metal transport and sensing. Chem Rev 2009; 109:4644-81. [PMID: 19788177 PMCID: PMC2783614 DOI: 10.1021/cr900077w] [Citation(s) in RCA: 433] [Impact Index Per Article: 28.9] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Zhen Ma
- Department of Chemistry, Indiana University, Bloomington, IN 47401-7005 USA
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843-2128 USA
| | - Faith E. Jacobsen
- Department of Chemistry, Indiana University, Bloomington, IN 47401-7005 USA
| | - David P. Giedroc
- Department of Chemistry, Indiana University, Bloomington, IN 47401-7005 USA
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62
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Colicchio R, Ricci S, Lamberti F, Pagliarulo C, Pagliuca C, Braione V, Braccini T, Talà A, Montanaro D, Tripodi S, Cintorino M, Troncone G, Bucci C, Pozzi G, Bruni CB, Alifano P, Salvatore P. The meningococcal ABC-Type L-glutamate transporter GltT is necessary for the development of experimental meningitis in mice. Infect Immun 2009; 77:3578-87. [PMID: 19528209 PMCID: PMC2737999 DOI: 10.1128/iai.01424-08] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2008] [Revised: 01/21/2009] [Accepted: 06/05/2009] [Indexed: 11/20/2022] Open
Abstract
Experimental animal models of bacterial meningitis are useful to study the host-pathogen interactions occurring at the cerebral level and to analyze the pathogenetic mechanisms behind this life-threatening disease. In this study, we have developed a mouse model of meningococcal meningitis based on the intracisternal inoculation of bacteria. Experiments were performed with mouse-passaged serogroup C Neisseria meningitidis. Survival and clinical parameters of infected mice and microbiological and histological analysis of the brain demonstrated the establishment of meningitis with features comparable to those of the disease in humans. When using low bacterial inocula, meningococcal replication in the brain was very efficient, with a 1,000-fold increase of viable counts in 18 h. Meningococci were also found in the blood, spleens, and livers of infected mice, and bacterial loads in different organs were dependent on the infectious dose. As glutamate uptake from the host has been implicated in meningococcal virulence, mice were infected intracisternally with an isogenic strain deficient in the ABC-type L-glutamate transporter GltT. Noticeably, the mutant was attenuated in virulence in mixed infections, indicating that wild-type bacteria outcompeted the GltT-deficient meningococci. The data show that the GltT transporter plays a role in meningitis and concomitant systemic infection, suggesting that meningococci may use L-glutamate as a nutrient source and as a precursor to synthesize the antioxidant glutathione.
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63
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Takahashi H. [Analyses of the pathogenesis in Neisseria meningitidis]. Nihon Saikingaku Zasshi 2009; 64:291-301. [PMID: 19628927 DOI: 10.3412/jsb.64.291] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
- Hideyuki Takahashi
- Department of Bacteriology, National Institute of Infectious Diseases, Tokyo, Japan
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64
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Abstract
The development of a comprehensive vaccine against meningococcal disease has been challenging. Recent developments in molecular genetics have provided both explanations for these challenges and possible solutions. Since genome sequence data became available there has been a marked increase in number of protein antigens that have been suggested as prospective vaccine components. This review catalogues the proposed vaccine candidates and examines the evidence for their inclusion in potential protein vaccine formulations.
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Affiliation(s)
- Ian M Feavers
- Division of Bacteriology, National Institute for Biological Standards and Control, Blanche Lane, South Mimms, Potters Bar, Hertfordshire EN6 3QG, United Kingdom.
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65
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Jordan PW, Saunders NJ. Host iron binding proteins acting as niche indicators for Neisseria meningitidis. PLoS One 2009; 4:e5198. [PMID: 19352437 PMCID: PMC2662411 DOI: 10.1371/journal.pone.0005198] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2007] [Accepted: 03/09/2009] [Indexed: 12/13/2022] Open
Abstract
Neisseria meningitidis requires iron, and in the absence of iron alters its gene expression to increase iron acquisition and to make the best use of the iron it has. During different stages of colonization and infection available iron sources differ, particularly the host iron-binding proteins haemoglobin, transferrin, and lactoferrin. This study compared the transcriptional responses of N. meningitidis, when grown in the presence of these iron donors and ferric iron, using microarrays. Specific transcriptional responses to the different iron sources were observed, including genes that are not part of the response to iron restriction. Comparisons between growth on haemoglobin and either transferrin or lactoferrin identified changes in 124 and 114 genes, respectively, and 33 genes differed between growth on transferrin or lactoferrin. Comparison of gene expression from growth on haemoglobin or ferric iron showed that transcription is also affected by the entry of either haem or ferric iron into the cytoplasm. This is consistent with a model in which N. meningitidis uses the relative availability of host iron donor proteins as niche indicators. Growth in the presence of haemoglobin is associated with a response likely to be adaptive to survival within the bloodstream, which is supported by serum killing assays that indicate growth on haemoglobin significantly increases survival, and the response to lactoferrin is associated with increased expression of epithelial cell adhesins and oxidative stress response molecules. The transferrin receptor is the most highly transcribed receptor and has the fewest genes specifically induced in its presence, suggesting this is the favoured iron source for the bacterium. Most strikingly, the responses to haemoglobin, which is associated with unrestricted growth, indicates a low iron transcriptional profile, associated with an aggressive phenotype that may be adaptive to access host iron sources but which may also underlie the lethal features of meningococcal septicaemia, when haemoglobin may become a major source of iron.
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Affiliation(s)
- Philip W. Jordan
- The Bacterial Pathogenesis and Functional Genomics Group, The Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom
| | - Nigel J. Saunders
- The Bacterial Pathogenesis and Functional Genomics Group, The Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom
- * E-mail:
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Phenotypic and genotypic analyses of Neisseria gonorrhoeae isolates that express frequently recovered PorB PIA variable region types suggest that certain P1a porin sequences confer a selective advantage for urogenital tract infection. Infect Immun 2008; 76:3700-9. [PMID: 18541655 DOI: 10.1128/iai.00265-08] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Typing of the porB variable region (VR) is an epidemiological tool that classifies gonococcal strains based on sequence differences in regions of the porB gene that encode surface-exposed loops. The frequent isolation of certain porB VR types suggests that some porin sequences confer a selective advantage during infection and/or transmission. Alternatively, certain porin types may be markers of strains that are successful due to factors unrelated to porin. In support of the first hypothesis, here we show urogenital tract isolates representing the most common PIA VR types identified in an urban clinic in Baltimore, MD, over a 10-year period belonged to several different clonal types, as determined by pulsed-field gel electrophoresis (PFGE). Serum resistance, which was confirmed by factor H and C4b-binding protein binding studies, was more often associated with gonococcal the most common VR types. In contrast, three porin-independent phenotypes, namely, lactoferrin utilization, beta-lactamase production, and multiple transferable resistance (Mtr), were segregated with the PFGE cluster and not with the VR type. Data combined with another PIA strain collection showed a strong correlation between serum resistance and the most common VR types. A comparison of VR typing hybridization patterns and nucleotide sequences of 12 porB1a genes suggests that certain porin loop 1, 3, 6, and/or 7 sequences may play a role in the serum resistance phenotype. We conclude that some PorB PIA sequences confer a survival or transmission advantage in the urogenital tract, perhaps via increased resistance to complement-mediated killing. The capacity of some porin types to evade a porin-specific adaptive immune response must also be considered.
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Spence JM, Wright L, Clark VL. Laboratory Maintenance of
Neisseria gonorrhoeae. ACTA ACUST UNITED AC 2008; Chapter 4:Unit 4A.1. [DOI: 10.1002/9780471729259.mc04a01s8] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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68
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Utilization of lactoferrin-bound and transferrin-bound iron by Campylobacter jejuni. J Bacteriol 2008; 190:1900-11. [PMID: 18203832 DOI: 10.1128/jb.01761-07] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Campylobacter jejuni NCTC 11168 was capable of growth to levels comparable with FeSO4 in defined iron-limited medium (minimal essential medium alpha [MEMalpha]) containing ferrilactoferrin, ferritransferrin, or ferri-ovotransferrin. Iron was internalized in a contact-dependent manner, with 94% of cell-associated radioactivity from either 55Fe-loaded transferrin or lactoferrin associated with the soluble cell fraction. Partitioning the iron source away from bacteria significantly decreased cellular growth. Excess cold transferrin or lactoferrin in cultures containing 55Fe-loaded transferrin or lactoferrin resulted in reduced levels of 55Fe uptake. Growth of C. jejuni in the presence of ferri- and an excess of apoprotein reduced overall levels of growth. Following incubation of cells in the presence of ferrilactoferrin, lactoferrin became associated with the cell surface; binding levels were higher after growth under iron limitation. A strain carrying a mutation in the cj0178 gene from the iron uptake system Cj0173c-Cj0178 demonstrated significantly reduced growth promotion in the presence of ferrilactoferrin in MEMalpha compared to wild type but was not affected in the presence of heme. Moreover, this mutant acquired less 55Fe than wild type when incubated with 55Fe-loaded protein and bound less lactoferrin. Complementation restored the wild-type phenotype when cells were grown with ferrilactoferrin. A mutant in the ABC transporter system permease gene (cj0174c) showed a small but significant growth reduction. The cj0176c-cj0177 intergenic region contains two separate Fur-regulated iron-repressible promoters. This is the first demonstration that C. jejuni is capable of acquiring iron from members of the transferrin protein family, and our data indicate a role for Cj0178 in this process.
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69
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Rodríguez JC, Zeng Y, Wilks A, Rivera M. The hydrogen-bonding network in heme oxygenase also functions as a modulator of enzyme dynamics: chaotic motions upon disrupting the H-bond network in heme oxygenase from Pseudomonas aeruginosa. J Am Chem Soc 2007; 129:11730-42. [PMID: 17764179 DOI: 10.1021/ja072405q] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Relaxation compensated Carr-Purcell-Meiboom-Gill (rc-CPMG) NMR experiments have been used to investigate micros-ms motions in heme oxygenase from Pseudomonas aeruginosa (pa-HO) in its ferric state, inhibited by CN- (pa-HO-CN) and N3- (pa-HO-N3), and in its ferrous state, inhibited by CO (pa-HO-CO). Comparative analysis of the data from the three forms indicates that the nature of the coordinated distal ligand affects the micros-ms conformational freedom of the polypeptide in regions of the enzyme far removed from the heme iron and distal ligand. Interpretation of the dynamical information in the context of the crystal structure of resting state pa-HO shows that residues involved in the network of structural hydrogen-bonded waters characteristic of HOs undergo micros-ms motions in pa-HO-CN, which was studied as a model of the highly paramagnetic S = 5/2 resting state form. In comparison, similar motions are suppressed in the pa-HO-CO and pa-HO-N3 complexes, which were studied as mimics of the obligatory oxyferrous and ferric hydroperoxide intermediates, respectively, in the catalytic cycle of heme degradation. These findings suggest that in addition to proton delivery to the nascent Fe(III)-OO(-) intermediate during catalysis, the hydrogen-bonding network serves two additional roles: (i) propagate the electronic state (reactive state) in each of the distinct steps of the catalytic cycle to key but remote sections of the polypeptide via small rearrangements in the network of hydrogen bonds and (ii) modulate the conformational freedom of the enzyme, thus allowing it to adapt to the demanding changes in axial coordination state and substrate transformations that take place during the catalytic cycle. This idea was probed by disrupting the hydrogen-bonding network in pa-HO by replacing R80 with L. NMR spectroscopic studies conducted with R80L-pa-HO-N3 and R80L-pa-HO-CO revealed that the mutant exhibits nearly global conformational disorder, which is absent in the equivalent complexes of the wild type enzyme. The "chaotic" disorder in the R80L mutant is likely related to its significantly lower efficiency to hydroxylate heme in the presence of H2O2, relative to the wild type enzyme.
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Affiliation(s)
- Juan Carlos Rodríguez
- Ralph N. Adams Institute for Bioanalytical Chemistry and Department of Chemistry, University of Kansas, Multidisciplinary Research Building, 2030 Becker Drive, Room 220 E, Lawrence, Kansas 66047, USA
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70
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Krewulak KD, Vogel HJ. Structural biology of bacterial iron uptake. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2007; 1778:1781-804. [PMID: 17916327 DOI: 10.1016/j.bbamem.2007.07.026] [Citation(s) in RCA: 326] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2007] [Revised: 07/20/2007] [Accepted: 07/24/2007] [Indexed: 11/19/2022]
Abstract
To fulfill their nutritional requirement for iron, bacteria utilize various iron sources which include the host proteins transferrin and lactoferrin, heme, and low molecular weight iron chelators termed siderophores. The iron sources are transported into the Gram-negative bacterial cell via specific uptake pathways which include an outer membrane receptor, a periplasmic binding protein (PBP), and an inner membrane ATP-binding cassette (ABC) transporter. Over the past two decades, structures for the proteins involved in bacterial iron uptake have not only been solved, but their functions have begun to be understood at the molecular level. However, the elucidation of the three dimensional structures of all components of the iron uptake pathways is currently limited. Despite the low sequence homology between different bacterial species, the available three-dimensional structures of homologous proteins are strikingly similar. Examination of the current three-dimensional structures of the outer membrane receptors, PBPs, and ABC transporters provides an overview of the structural biology of iron uptake in bacteria.
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Affiliation(s)
- Karla D Krewulak
- Structural Biology Research Group, Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada T2N 1N4
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71
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Weynants VE, Feron CM, Goraj KK, Bos MP, Denoël PA, Verlant VG, Tommassen J, Peak IRA, Judd RC, Jennings MP, Poolman JT. Additive and synergistic bactericidal activity of antibodies directed against minor outer membrane proteins of Neisseria meningitidis. Infect Immun 2007; 75:5434-42. [PMID: 17664268 PMCID: PMC2168297 DOI: 10.1128/iai.00411-07] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Neisseria meningitidis serogroup B is a major cause of bacterial meningitis in younger populations. The available vaccines are based on outer membrane vesicles obtained from wild-type strains. In children less than 2 years old they confer protection only against strains expressing homologous PorA, a major, variable outer membrane protein (OMP). We genetically modified a strain in order to eliminate PorA and to overproduce one or several minor and conserved OMPs. Using a mouse model mimicking children's PorA-specific bactericidal activity, it was demonstrated that overproduction of more than one minor OMP is required to elicit antibodies able to induce complement-mediated killing of strains expressing heterologous PorA. It is concluded that a critical density of bactericidal antibodies needs to be reached at the surface of meningococci to induce complement-mediated killing. With minor OMPs, this threshold is reached when more than one antigen is targeted, and this allows cross-protection.
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Affiliation(s)
- Vincent E Weynants
- GlaxoSmithKline Biologicals, Rue de l'Institut 89, B-1330 Rixensart, Belgium
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72
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Asuthkar S, Velineni S, Stadlmann J, Altmann F, Sritharan M. Expression and characterization of an iron-regulated hemin-binding protein, HbpA, from Leptospira interrogans serovar Lai. Infect Immun 2007; 75:4582-91. [PMID: 17576761 PMCID: PMC1951163 DOI: 10.1128/iai.00324-07] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In an earlier study, based on the ferric enterobactin receptor FepA of Escherichia coli, we identified and modeled a TonB-dependent outer membrane receptor protein (LB191) from the genome of Leptospira interrogans serovar Lai. Based on in silico analysis, we hypothesized that this protein was an iron-dependent hemin-binding protein. In this study, we provide experimental evidence to prove that this protein, termed HbpA (hemin-binding protein A), is indeed an iron-regulated hemin-binding protein. We cloned and expressed the full-length 81-kDa recombinant rHbpA protein and a truncated 55-kDa protein from L. interrogans serovar Lai, both of which bind hemin-agarose. Assay of hemin-associated peroxidase activity and spectrofluorimetric analysis provided confirmatory evidence of hemin binding by HbpA. Immunofluorescence studies by confocal microscopy and the microscopic agglutination test demonstrated the surface localization and the iron-regulated expression of HbpA in L. interrogans. Southern blot analysis confirmed our earlier observation that the hbpA gene was present only in some of the pathogenic serovars and was absent in Leptospira biflexa. Hemin-agarose affinity studies showed another hemin-binding protein with a molecular mass of approximately 44 kDa, whose expression was independent of iron levels. This protein was seen in several serovars, including nonpathogenic L. biflexa. Sequence analysis and immunoreactivity with specific antibodies showed this protein to be LipL41.
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Affiliation(s)
- Swapna Asuthkar
- School of Life Sciences, University of Hyderabad, Gachibowli, Hyderabad 500046, India
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73
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Khan A, Shouldice S, Kirby S, Yu RH, Tari L, Schryvers A. High-affinity binding by the periplasmic iron-binding protein from Haemophilus influenzae is required for acquiring iron from transferrin. Biochem J 2007; 404:217-25. [PMID: 17313366 PMCID: PMC1868806 DOI: 10.1042/bj20070110] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The periplasmic iron-binding protein, FbpA (ferric-ion-binding protein A), performs an essential role in iron acquisition from transferrin in Haemophilus influenzae. A series of site-directed mutants in the metal-binding amino acids of FbpA were prepared to determine their relative contribution to iron binding and transport. Structural studies demonstrated that the mutant proteins crystallized in an open conformation with the iron atom associated with the C-terminal domain. The iron-binding properties of the mutant proteins were assessed by several assays, including a novel competitive iron-binding assay. The relative ability of the proteins to compete for iron was pH dependent, with a rank order at pH 6.5 of wild-type, Q58L, H9Q>H9A, E57A>Y195A, Y196A. The genes encoding the mutant FbpA were introduced into H. influenzae and the resulting strains varied in the level of ferric citrate required to support growth on iron-limited medium, suggesting a rank order for metal-binding affinities under physiological conditions comparable with the competitive binding assay at pH 6.5 (wild-type=Q58L>H9Q>H9A, E57A>Y195A, Y196A). Growth dependence on human transferrin was only obtained with cells expressing wild-type, Q58L or H9Q FbpAs, proteins with stability constants derived from the competition assay >2.0x10(18) M(-1). These results suggest that a relatively high affinity of iron binding by FbpA is required for removal of iron from transferrin and its transport across the outer membrane.
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Affiliation(s)
- Ali G. Khan
- *Department of Microbiology and Infectious Diseases, University of Calgary, Calgary, AB, Canada T2N 4N1
| | - Stephen R. Shouldice
- *Department of Microbiology and Infectious Diseases, University of Calgary, Calgary, AB, Canada T2N 4N1
| | - Shane D. Kirby
- *Department of Microbiology and Infectious Diseases, University of Calgary, Calgary, AB, Canada T2N 4N1
| | - Rong-hua Yu
- *Department of Microbiology and Infectious Diseases, University of Calgary, Calgary, AB, Canada T2N 4N1
| | | | - Anthony B. Schryvers
- *Department of Microbiology and Infectious Diseases, University of Calgary, Calgary, AB, Canada T2N 4N1
- To whom correspondence should be addressed (email )
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74
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Anderson DS, Adhikari P, Weaver KD, Crumbliss AL, Mietzner TA. The Haemophilus influenzae hFbpABC Fe3+ transporter: analysis of the membrane permease and development of a gallium-based screen for mutants. J Bacteriol 2007; 189:5130-41. [PMID: 17496104 PMCID: PMC1951847 DOI: 10.1128/jb.00145-07] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The obligate human pathogen Haemophilus influenzae utilizes a siderophore-independent (free) Fe(3+) transport system to obtain this essential element from the host iron-binding protein transferrin. The hFbpABC transporter is a binding protein-dependent ABC transporter that functions to shuttle (free) Fe(3+) through the periplasm and across the inner membrane of H. influenzae. This investigation focuses on the structure and function of the hFbpB membrane permease component of the transporter, a protein that has eluded prior characterization. Based on multiple-sequence alignments between permease orthologs, a series of site-directed mutations targeted at residues within the two conserved permease motifs were generated. The hFbpABC transporter was expressed in a siderophore-deficient Escherichia coli background, and effects of mutations were analyzed using growth rescue and radiolabeled (55)Fe(3+) transport assays. Results demonstrate that mutation of the invariant glycine (G418A) within motif 2 led to attenuated transport activity, while mutation of the invariant glycine (G155A/V/E) within motif 1 had no discernible effect on activity. Individual mutations of well-conserved leucines (L154D and L417D) led to attenuated and null transport activities, respectively. As a complement to site-directed methods, a mutant screen based on resistance to the toxic iron analog gallium, an hFbpABC inhibitor, was devised. The screen led to the identification of several significant hFbpB mutations; V497I, I174F, and S475I led to null transport activities, while S146Y resulted in attenuated activity. Significant residues were mapped to a topological model of the hFbpB permease, and the implications of mutations are discussed in light of structural and functional data from related ABC transporters.
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Affiliation(s)
- Damon S Anderson
- Department of Molecular Genetics and Biochemistry, University of Pittsburgh School of Medicine, E1240 Biomedical Science Tower, Lothrop Street, Pittsburgh, PA 15261, USA
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75
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Basler M, Linhartová I, Halada P, Novotná J, Bezousková S, Osicka R, Weiser J, Vohradský J, Sebo P. The iron-regulated transcriptome and proteome of Neisseria meningitidis serogroup C. Proteomics 2007; 6:6194-206. [PMID: 17133369 DOI: 10.1002/pmic.200600312] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Restricting bacterial growth by iron-chelating proteins that reduce iron availability in mucosal secretions and body fluids belongs to basic mechanisms of innate immunity. Most pathogens and commensals thus developed gene regulons responding to iron concentration and encoding iron acquisition systems and genes involved in host colonization and virulence. Here, we analyzed the steady-state composition of the iron-regulated proteome and transcriptome of an invasive serogroup C clinical isolate of Neisseria meningitidis. The proteome of meningococci grown under iron-depleted and iron-replete conditions was analyzed by 2-DE and proteins exhibiting significantly altered expression were identified by MALDI-TOF MS analysis. In parallel, total RNA was isolated from the same cultures and iron-regulated genes were identified using whole-genome DNA microarrays. The proteome and the transcriptome were found to overlap by only 19 iron-regulated genes/proteins, with 111 genes/proteins being significantly up-regulated in iron-replete cultures and 130 genes/proteins being up-regulated during iron starvation, respectively. Comparisons with published transcriptomic data for N. meningitidis serogroup B, moreover, indicate that expression of up to 20% of all meningococcal genes can be subject to regulation in function of iron availability.
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MESH Headings
- Deferoxamine/pharmacology
- Electrophoresis, Gel, Two-Dimensional
- Ferric Compounds/pharmacology
- Gene Expression Regulation, Bacterial/drug effects
- Iron/pharmacology
- Neisseria gonorrhoeae/drug effects
- Neisseria gonorrhoeae/metabolism
- Neisseria meningitidis, Serogroup B/drug effects
- Neisseria meningitidis, Serogroup B/metabolism
- Neisseria meningitidis, Serogroup C/drug effects
- Neisseria meningitidis, Serogroup C/metabolism
- Nitrates/pharmacology
- Oligonucleotide Array Sequence Analysis
- Proteome
- Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
- Transcription, Genetic
- Up-Regulation
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Affiliation(s)
- Marek Basler
- Institute of Microbiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic.
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76
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Kortekaas J, Pettersson A, van der Biezen J, Weynants VE, van der Ley P, Poolman J, Bos MP, Tommassen J. Shielding of immunogenic domains in Neisseria meningitidis FrpB (FetA) by the major variable region. Vaccine 2007; 25:72-84. [PMID: 16914236 DOI: 10.1016/j.vaccine.2006.07.016] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2006] [Revised: 07/12/2006] [Accepted: 07/13/2006] [Indexed: 10/24/2022]
Abstract
The meningococcal iron-limitation-inducible outer membrane protein FrpB (FetA) has been shown to induce bactericidal antibodies, and is, therefore, considered a vaccine candidate. However, these antibodies are strain specific and, consistently, epitope mapping showed that they are directed against a region, located in a surface-exposed loop, L5, that displays considerable sequence variability between strains. Here, we attempted to redirect the immune response to more conserved domains of the protein by deleting L5. Immunization with an FrpB protein lacking L5 resulted in a bactericidal antibody response, and epitope mapping showed that these antibodies were directed against loop L3, which also displays considerable sequence variability. To re-direct the immune response further, immunizations were performed with an FrpB protein lacking both L5 and L3. The antibodies obtained were not bactericidal. Furthermore, the bactericidal antibodies against L3 were only bactericidal in the absence of L5, and immunofluorescence microscopy experiments showed that L5 efficiently shields other immunogenic cell surface-exposed epitopes outside of this region on living cells. Whereas the ability of micro-organisms to vary surface-exposed domains that are targets for protective immunity has long been established, the current work shows that such domains can be remarkably efficient in shielding other, more conserved epitopes.
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Affiliation(s)
- Jeroen Kortekaas
- Department of Molecular Microbiology and Institute of Biomembranes, Utrecht University, Padualaan, 3584 CH Utrecht, The Netherlands
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77
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Abstract
In this critical review we discuss recent advances in understanding the modes of interaction of metal ions with membrane proteins, including channels, pumps, transporters, ATP-binding cassette proteins, G-protein coupled receptors, kinases and respiratory enzymes. Such knowledge provides a basis for elucidating the mechanism of action of some classes of metallodrugs, and a stimulus for the further exploration of the coordination chemistry of metal ions in membranes. Such research offers promise for the discovery of new drugs with unusual modes of action. The article will be of interest to bioinorganic chemists, chemical biologists, biochemists, pharmacologists and medicinal chemists. (247 references).
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Affiliation(s)
- Xiangyang Liang
- School of Chemistry, University of Edinburgh, King's Buildings, West Mains Road, Edinburgh, UKEH9 3JJ
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78
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Deka RK, Brautigam CA, Tomson FL, Lumpkins SB, Tomchick DR, Machius M, Norgard MV. Crystal structure of the Tp34 (TP0971) lipoprotein of treponema pallidum: implications of its metal-bound state and affinity for human lactoferrin. J Biol Chem 2006; 282:5944-58. [PMID: 17192261 DOI: 10.1074/jbc.m610215200] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The Tp34 (TP0971) membrane lipoprotein of Treponema pallidum, an obligate human pathogen and the agent of syphilis, was previously reported to have lactoferrin binding properties. Given the non-cultivatable nature of T. pallidum, a structure-to-function approach was pursued to clarify further potential relationships between the Tp34 structural and biochemical properties and its propensity to bind human lactoferrin. The crystal structure of a nonacylated, recombinant form of Tp34 (rTp34), solved to a resolution of 1.9A(,) revealed two metaloccupied binding sites within a dimer; the identity of the ion most likely was zinc. Residues from both of the monomers contributed to the interfacial metal-binding sites; a novel feature was that the delta-sulfur of methionine coordinated the zinc ion. Analytical ultracentrifugation showed that, in solution, rTp34 formed a metal-stabilized dimer and that rTp34 bound human lactoferrin with a stoichiometry of 2:1. Isothermal titration calorimetry further revealed that rTp34 bound human lactoferrin at high (submicromolar) affinity. Finally, membrane topology studies revealed that native Tp34 is not located on the outer surface (outer membrane) of T. pallidum but, rather, is periplasmic. How propensity of Tp34 to bind zinc and the iron-sequestering lactoferrin may relate overall to the biology of T. pallidum infection in humans is discussed.
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Affiliation(s)
- Ranjit K Deka
- Departments of Microbiology and Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
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79
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Chakraborty R, Storey E, van der Helm D. Molecular mechanism of ferricsiderophore passage through the outer membrane receptor proteins of Escherichia coli. Biometals 2006; 20:263-74. [PMID: 17186377 DOI: 10.1007/s10534-006-9060-9] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2006] [Accepted: 11/28/2006] [Indexed: 10/23/2022]
Abstract
Iron is an essential nutrient for all microorganisms with a few exceptions. Microorganisms use a variety of systems to acquire iron from the surrounding environment. One such system includes production of an organic molecule known as a siderophore by many bacteria and fungi. Siderophores have the capacity to specifically chelate ferric ions. The ferricsiderophore complex is then transported into the cell via a specific receptor protein located in the outer membrane. This is an energy dependent process and is the subject of investigation in many research laboratories. The crystal structures of three outer membrane ferricsiderophore receptor proteins FepA, FhuA and FecA from Escherichia coli and two FpvA and FptA from Pseudomonas aeruginosa have recently been solved. Four of them, FhuA, FecA, FpvA and FptA have been solved in ligand-bound forms, which gave insight into the residues involved in ligand binding. The structures are similar and show the presence of similar domains; for example, all of them consist of a 22 strand-beta-barrel formed by approximately 600 C-terminal residues while approximately 150 N-terminal residues fold inside the barrel to form a plug domain. The plug domain obstructs the passage through the barrel; therefore our research focuses on the mechanism through which the ferricsiderophore complex is transported across the receptor into the periplasm. There are two possibilities, one in which the plug domain is expelled into the periplasm making way for the ferricsiderophore complex and the second in which the plug domain undergoes structural rearrangement to form a channel through which the complex slides into the periplasm. Multiple alignment studies involving protein sequences of a large number of outer membrane receptor proteins that transport ferricsiderophores have identified several conserved residues. All of the conserved residues are located within the plug and barrel domain below the ligand binding site. We have substituted a number of these residues in FepA and FhuA with either alanine or glutamine resulting in substantial changes in the chemical properties of the residues. This was done to study the effect of the substitutions on the transport of ferricsiderophores. Another strategy used was to create a disulfide bond between the residues located on two adjacent beta-strands of the plug domain or between the residues of the plug domain and the beta-barrel in FhuA by substituting appropriate residues with cysteine. We have looked for the variants where the transport is affected without altering the binding. The data suggest a distinct role of these residues in the mechanism of transport. Our data also indicate that these transporters share a common mechanism of transport and that the plug remains within the barrel and possibly undergoes rearrangement to form a channel to transport the ferricsiderophore from the binding site to the periplasm.
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Affiliation(s)
- Ranjan Chakraborty
- Department of Health Sciences, College of Public and Allied Health, East Tennessee State University, Johnson City, TN 37614, USA.
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80
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Williams JN, Skipp PJ, Humphries HE, Christodoulides M, O'Connor CD, Heckels JE. Proteomic analysis of outer membranes and vesicles from wild-type serogroup B Neisseria meningitidis and a lipopolysaccharide-deficient mutant. Infect Immun 2006; 75:1364-72. [PMID: 17158897 PMCID: PMC1828559 DOI: 10.1128/iai.01424-06] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Current experimental vaccines against serogroup B Neisseria meningitidis are based on meningococcal outer membrane (OM) proteins present in outer membrane vesicles (OMV) in which toxic lipopolysaccharide is depleted by detergent extraction. Knowledge of the composition of OM and OMV is essential for developing new meningococcal vaccines based on defined antigens. In the current study, sodium dodecyl sulfate-polyacrylamide gel electrophoresis and nanocapillary liquid chromatography-tandem mass spectrometry were used to investigate the proteomes of OM and OMV from meningococcal strain MC58 and OM from a lipopolysaccharide-deficient mutant. The analysis of OM revealed a composition that was much more complex than the composition that has been reported previously; a total of 236 proteins were identified, only 6.4% of which were predicted to be located in the outer membrane. The most abundant proteins included not only the well-established major OM proteins (PorA, PorB, Opc, Rmp, and Opa) but also other proteins, such as pilus-associated protein Q (PilQ) and a putative macrophage infectivity protein. All of these proteins were also present in OMV obtained by extraction of the OM with deoxycholate. There were markedly increased levels of some additional proteins in OM from the lipopolysaccharide-deficient mutant, including enzymes that contribute to the tricarboxylic acid cycle. In all the preparations, the proteins not predicted to have an OM location were predominantly periplasmic or cytoplasmic or had an unknown location, and relatively few cytoplasmic membrane proteins were detected. However, several proteins that have previously been identified as potential vaccine candidates were not detected in either OM preparations or in OMV. These results have important implications for the development and use of vaccines based on outer membrane proteins.
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Affiliation(s)
- Jeannette N Williams
- Molecular Microbiology Group, Division of Infection Inflammation and Repair, University of Southampton Medical School, Southampton General Hospital, Southampton SO16 6YD, United Kingdom
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81
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Eichhorn H, Lessing F, Winterberg B, Schirawski J, Kämper J, Müller P, Kahmann R. A ferroxidation/permeation iron uptake system is required for virulence in Ustilago maydis. THE PLANT CELL 2006; 18:3332-45. [PMID: 17138696 PMCID: PMC1693961 DOI: 10.1105/tpc.106.043588] [Citation(s) in RCA: 130] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2006] [Revised: 10/18/2006] [Accepted: 11/02/2006] [Indexed: 05/12/2023]
Abstract
In the smut fungus Ustilago maydis, a tightly regulated cAMP signaling cascade is necessary for pathogenic development. Transcriptome analysis using whole genome microarrays set up to identify putative target genes of the protein kinase A catalytic subunit Adr1 revealed nine genes with putative functions in two high-affinity iron uptake systems. These genes locate to three gene clusters on different chromosomes and include the previously identified complementing siderophore auxotroph genes sid1 and sid2 involved in siderophore biosynthesis. Transcription of all nine genes plus three additional genes associated with the gene clusters was also coregulated by iron through the Urbs1 transcription factor. Two components of a high-affinity iron uptake system were characterized in more detail: fer2, encoding a high-affinity iron permease; and fer1, encoding an iron multicopper oxidase. Fer2 localized to the plasma membrane and complemented an ftr1 mutant of Saccharomyces cerevisiae lacking a high-affinity iron permease. During pathogenic development, fer2 expression was confined to the phase of hyphal proliferation inside the plant. fer2 as well as fer1 deletion mutants were strongly affected in virulence. These data highlight the importance of the high-affinity iron uptake system via an iron permease and a multicopper oxidase for biotrophic development in the U. maydis/maize (Zea mays) pathosystem.
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Affiliation(s)
- Heiko Eichhorn
- Max Planck Institute for Terrestrial Microbiology, D-35043 Marburg, Germany
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82
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Wyckoff EE, Mey AR, Leimbach A, Fisher CF, Payne SM. Characterization of ferric and ferrous iron transport systems in Vibrio cholerae. J Bacteriol 2006; 188:6515-23. [PMID: 16952942 PMCID: PMC1595488 DOI: 10.1128/jb.00626-06] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Vibrio cholerae has multiple iron acquisition systems, including TonB-dependent transport of heme and of the catechol siderophore vibriobactin. Strains defective in both of these systems grow well in laboratory media and in the infant mouse intestine, indicating the presence of additional iron acquisition systems. Previously uncharacterized potential iron transport systems, including a homologue of the ferrous transporter Feo and a periplasmic binding protein-dependent ATP binding cassette (ABC) transport system, termed Fbp, were identified in the V. cholerae genome sequence. Clones encoding either the Feo or the Fbp system exhibited characteristics of iron transporters: both repressed the expression of lacZ cloned under the control of a Fur-regulated promoter in Escherichia coli and also conferred growth on a Shigella flexneri mutant that has a severe defect in iron transport. Two other ABC transporters were also evaluated but were negative by these assays. Transport of radioactive iron by the Feo system into the S. flexneri iron transport mutant was stimulated by the reducing agent ascorbate, consistent with Feo functioning as a ferrous transporter. Conversely, ascorbate inhibited transport by the Fbp system, suggesting that it transports ferric iron. The growth of V. cholerae strains carrying mutations in one or more of the potential iron transport genes indicated that both Feo and Fbp contribute to iron acquisition. However, a mutant defective in the vibriobactin, Fbp, and Feo systems was not attenuated in a suckling mouse model, suggesting that at least one other iron transport system can be used in vivo.
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Affiliation(s)
- Elizabeth E Wyckoff
- University of Texas, Section of Molecular Genetics and Microbiology, 1 University Station A5000, Austin, TX 78712-0162, USA.
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83
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Wilhelm V, Miquel A, Burzio LO, Rosemblatt M, Engel E, Valenzuela S, Parada G, Valenzuela PDT. A vaccine against the salmonid pathogen Piscirickettsia salmonis based on recombinant proteins. Vaccine 2006; 24:5083-91. [PMID: 16697089 DOI: 10.1016/j.vaccine.2006.03.027] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2005] [Revised: 03/08/2006] [Accepted: 03/14/2006] [Indexed: 11/18/2022]
Abstract
We report here the protective effect against piscirickettsiosis elicited in fish by a mixture of recombinant proteins. A comparative genomics strategy was used on a genomic library of Piscirickettsia salmonis in order to select optimal candidates for a recombinant subunit vaccine to protect fish from rickettsial septicaemia (SRS). Based on this information, 15 P. salmonis ORFs encoding heat shock proteins, virulence factors, membrane bound and other surface exposed antigens, were isolated and expressed. Seven of the most promising antigens were formulated in three mixtures (V1-V3) containing two or three recombinant proteins each and injected into salmon to test their protective efficacy. Two of the three formulations (V1, V2) elicited a strong protective response in a challenge against the pathogen, which was coincident with the humoral response against the corresponding recombinant proteins present in each formulation. V1, formulated with recombinant chaperonines Hsp60, Hsp70 and flagellar protein FlgG of P. salmonis achieved the highest level of protection with a relative percent survival (RPS) of 95%.
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Affiliation(s)
- Vivian Wilhelm
- Fundación Ciencia para la Vida and Instituto Milenio de Biología Fundamental y Aplicada, Zañartu 1482, Santiago, Chile
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84
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Sardiñas G, Reddin K, Pajon R, Gorringe A. Outer membrane vesicles of Neisseria lactamica as a potential mucosal adjuvant. Vaccine 2006; 24:206-14. [PMID: 16115701 DOI: 10.1016/j.vaccine.2005.07.064] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2005] [Accepted: 07/25/2005] [Indexed: 11/24/2022]
Abstract
The muscosal delivery of vaccines has many advantages including ease of administration and the induction of a mucosal immune response at the natural site of infection for many pathogens. Mice were immunised with outer membrane vesicles (OMV) prepared from Neisseria lactamica or Neisseria meningitidis by subcutaneous (SC) or intranasal (IN) routes, or live cells of N. lactamica given IN or by SC injection. A systemic IgG and mucosal IgA response was demonstrated and N. lactamica OMV induced antibodies cross-reactive with N. meningitidis; however, a cross-reactive response following IN administration was only evident after three doses of vaccine. OMV from both organisms were also an effective intranasal adjuvant for a co-administered model antigen, hepatitis B surface antigen (HBsAg), inducing systemic IgG against HBsAg and IgA in lung and vaginal washes. IN administration of N. meningitidis OMV elicited serum antibodies that were bactericidal for meningococci and provided passive protection in an infant rat model of meningococcal bacteraemia. The antibody response to N. lactamica OMV given IN was only weakly bactericidal but still afforded passive protection. Thus, OMV from N. lactamica given IN elicit immune responses cross-reactive with N. meningitidis and act as an effective mucosal adjuvant.
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Affiliation(s)
- Gretel Sardiñas
- Center For Genetic Engineering and Biotechnology, Ave. 31e/158 y 190, Cubanacán, P.O. Box 6162, 10600 Habana, Cuba
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85
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Yamanaka K, Oikawa H, Ogawa HO, Hosono K, Shinmachi F, Takano H, Sakuda S, Beppu T, Ueda K. Desferrioxamine E produced by Streptomyces griseus stimulates growth and development of Streptomyces tanashiensis. MICROBIOLOGY-SGM 2005; 151:2899-2905. [PMID: 16151202 DOI: 10.1099/mic.0.28139-0] [Citation(s) in RCA: 132] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The authors previously reported that interspecific stimulatory events between Streptomyces species for antibiotic production and/or morphological differentiation mediated by putative diffusible metabolites take place at a high frequency. This paper reports the isolation and characterization of a substance produced by Streptomyces griseus that stimulates the growth and development of Streptomyces tanashiensis. The substance was purified from the culture supernatant of S. griseus by using anion-exchange chromatography, gel filtration chromatography and reverse-phase HPLC. FAB-MS and NMR analyses of the purified preparation indicated the substance to be desferrioxamine E (synonym: nocardamine), a siderophore that is widely produced by Streptomyces species and related organisms. Similar stimulatory effects on the growth and development of S. tanashiensis were exerted by desferrioxamine E produced by another actinomycete strain, but not by other siderophores tested, including ferrichrome and nocobactin and free ferric ion. An exogenous supply of desferrioxamine E stimulated secondary metabolite formation and/or morphological differentiation in various actinomycete strains. Disruption of the desferrioxamine biosynthesis gene cluster in Streptomyces coelicolor A3(2) abolished the production of desferrioxamine E and the activity to stimulate the growth and differentiation of S. tanashiensis. The S. coelicolor mutant showed impaired growth and development on Bennett's/glucose agar medium, but it was rescued by the exogenous supply of desferrioxamine E. These results indicate that desferrioxamines play an important role in streptomycete physiology. Similar to several pathogenic bacteria and fungi, S. tanashiensis may be defective in the production of siderophores; however, it can utilize the siderophores excreted by other organisms.
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Affiliation(s)
- Kazuki Yamanaka
- Life Science Research Center, College of Bioresource Sciences, Nihon University, 1866 Kameino, Fujisawa 252-8510, Japan
| | - Hiroaki Oikawa
- Life Science Research Center, College of Bioresource Sciences, Nihon University, 1866 Kameino, Fujisawa 252-8510, Japan
| | - Hiro-Omi Ogawa
- Life Science Research Center, College of Bioresource Sciences, Nihon University, 1866 Kameino, Fujisawa 252-8510, Japan
| | - Kuniaki Hosono
- Life Science Research Center, College of Bioresource Sciences, Nihon University, 1866 Kameino, Fujisawa 252-8510, Japan
| | - Fumie Shinmachi
- Department of Agriculture, Junior College, Nihon University, 1866 Kameino, Fujisawa 252-8510, Japan
| | - Hideaki Takano
- Life Science Research Center, College of Bioresource Sciences, Nihon University, 1866 Kameino, Fujisawa 252-8510, Japan
| | - Shohei Sakuda
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Teruhiko Beppu
- Life Science Research Center, College of Bioresource Sciences, Nihon University, 1866 Kameino, Fujisawa 252-8510, Japan
| | - Kenji Ueda
- Life Science Research Center, College of Bioresource Sciences, Nihon University, 1866 Kameino, Fujisawa 252-8510, Japan
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86
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Brettin T, Altherr MR, Du Y, Mason RM, Friedrich A, Potter L, Langford C, Keller TJ, Jens J, Howie H, Weyand NJ, Clary S, Prichard K, Wachocki S, Sodergren E, Dillard JP, Weinstock G, So M, Arvidson CG. Expression capable library for studies of Neisseria gonorrhoeae, version 1.0. BMC Microbiol 2005; 5:50. [PMID: 16137322 PMCID: PMC1236931 DOI: 10.1186/1471-2180-5-50] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2005] [Accepted: 09/01/2005] [Indexed: 11/25/2022] Open
Abstract
BACKGROUND The sexually transmitted disease, gonorrhea, is a serious health problem in developed as well as in developing countries, for which treatment continues to be a challenge. The recent completion of the genome sequence of the causative agent, Neisseria gonorrhoeae, opens up an entirely new set of approaches for studying this organism and the diseases it causes. Here, we describe the initial phases of the construction of an expression-capable clone set representing the protein-coding ORFs of the gonococcal genome using a recombination-based cloning system. RESULTS The clone set thus far includes 1672 of the 2250 predicted ORFs of the N. gonorrhoeae genome, of which 1393 (83%) are sequence-validated. Included in this set are 48 of the 61 ORFs of the gonococcal genetic island of strain MS11, not present in the sequenced genome of strain FA1090. L-arabinose-inducible glutathione-S-transferase (GST)-fusions were constructed from random clones and each was shown to express a fusion protein of the predicted size following induction, demonstrating the use of the recombination cloning system. PCR amplicons of each ORF used in the cloning reactions were spotted onto glass slides to produce DNA microarrays representing 2035 genes of the gonococcal genome. Pilot experiments indicate that these arrays are suitable for the analysis of global gene expression in gonococci. CONCLUSION This archived set of Gateway entry clones will facilitate high-throughput genomic and proteomic studies of gonococcal genes using a variety of expression and analysis systems. In addition, the DNA arrays produced will allow us to generate gene expression profiles of gonococci grown in a wide variety of conditions. Together, the resources produced in this work will facilitate experiments to dissect the molecular mechanisms of gonococcal pathogenesis on a global scale, and ultimately lead to the determination of the functions of unknown genes in the genome.
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Affiliation(s)
- Thomas Brettin
- Bioscience Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA
| | - Michael R Altherr
- Bioscience Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA
| | - Ying Du
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI 48824-4320, USA
| | - Roxie M Mason
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI 48824-4320, USA
| | - Alexandra Friedrich
- Department of Molecular Microbiology and Immunology, Oregon Health and Science University, Portland, OR 97201-3098, USA
| | - Laura Potter
- Department of Molecular Microbiology and Immunology, Oregon Health and Science University, Portland, OR 97201-3098, USA
- Leicester Warwick Medical School, University of Warwick, Coventry, UK
| | - Chris Langford
- Department of Molecular Microbiology and Immunology, Oregon Health and Science University, Portland, OR 97201-3098, USA
| | - Thomas J Keller
- Department of Molecular Microbiology and Immunology, Oregon Health and Science University, Portland, OR 97201-3098, USA
| | - Jason Jens
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI 48824-4320, USA
| | - Heather Howie
- Department of Molecular Microbiology and Immunology, Oregon Health and Science University, Portland, OR 97201-3098, USA
| | - Nathan J Weyand
- Department of Molecular Microbiology and Immunology, Oregon Health and Science University, Portland, OR 97201-3098, USA
| | - Susan Clary
- Department of Molecular Microbiology and Immunology, Oregon Health and Science University, Portland, OR 97201-3098, USA
| | - Kimberly Prichard
- Bioscience Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA
| | - Susi Wachocki
- Bioscience Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA
| | - Erica Sodergren
- Human Genome Sequencing Center, Baylor College of Medicine, Houston TX 77030, USA
| | - Joseph P Dillard
- Department of Medical Microbiology and Immunology, University of Wisconsin Medical School, Madison, WI 53706, USA
| | - George Weinstock
- Human Genome Sequencing Center, Baylor College of Medicine, Houston TX 77030, USA
| | - Magdalene So
- Department of Molecular Microbiology and Immunology, Oregon Health and Science University, Portland, OR 97201-3098, USA
| | - Cindy Grove Arvidson
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI 48824-4320, USA
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87
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Shivachandra SB, Kumar AA, Amaranath J, Joseph S, Srivastava SK, Chaudhuri P. Cloning and Characterization of tbpA Gene Encoding Transferrin-Binding Protein (TbpA) from Pasteurella multocida Serogroup B:2 (strain P52). Vet Res Commun 2005; 29:537-42. [PMID: 16215844 DOI: 10.1007/s11259-005-2495-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/10/2004] [Indexed: 11/25/2022]
Affiliation(s)
- S B Shivachandra
- Division of Bacteriology and Mycology, Indian Veterinary Research Institute, Izatnagar 243122, UP, India.
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88
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Møller JD, Ellis AE, Barnes AC, Dalsgaard I. Iron acquisition mechanisms of Flavobacterium psychrophilum. JOURNAL OF FISH DISEASES 2005; 28:391-8. [PMID: 16083444 DOI: 10.1111/j.1365-2761.2005.00639.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Forty strains of Flavobacterium psychrophilum were tested for the production of siderophores using the universal Chrome Azurol S (CAS) assay. The majority of the strains (85%) were CAS positive (CAS+) and some (15%) were CAS negative (CAS-). The cryptic plasmid pCP1 was carried by all positive strains and was lacking from negative strains. While a weak catechol reaction was detectable in CAS+ culture supernatants, the CAS reaction was, to some extent, heat sensitive, questioning whether the positive reaction was caused only by siderophores. The ability to grow in vitro under iron-restricted conditions did not correlate with the CAS reactivity, as growth of both CAS+ and CAS- strains was similarly impaired under iron restriction induced by 2,2 dipyridyl. Suppressed growth under these conditions was restored by addition of FeCl3, haemoglobin and transferrin for both CAS+ and CAS- strains.
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Affiliation(s)
- J D Møller
- Fish Disease Laboratory, Danish Institute for Fisheries Research, Frederiksberg, Denmark.
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89
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Furano K, Luke NR, Howlett AJ, Campagnari AA. Identification of a conserved Moraxella catarrhalis haemoglobin-utilization protein, MhuA. MICROBIOLOGY-SGM 2005; 151:1151-1158. [PMID: 15817782 DOI: 10.1099/mic.0.27820-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Moraxella catarrhalis is a leading cause of acute otitis media in children and is a cause of respiratory disease in adults with underlying lung disease. This organism is a strict human pathogen that has an absolute requirement for iron in order to grow and cause disease. Previous studies identified transferrin and lactoferrin receptors used by M. catarrhalis to obtain iron from the human host, yet other iron-acquisition systems remain undefined. In this study, it is demonstrated that this strict mucosal pathogen can utilize haemoglobin (Hb) as a sole source of iron for growth. A novel 107 kDa outer-membrane protein involved in Hb utilization by this pathogen was also identified. An isogenic mutant defective in this Moraxella Hb-utilization protein (MhuA), 7169 : : mhuA, showed a significant lag during growth in the presence of Hb as the sole iron source. This protein appears to be expressed constitutively, regardless of growth conditions, and a mAb directed to MhuA demonstrated that this protein contains highly conserved, surface-exposed epitopes. Data demonstrating that expression of MhuA may be highly specific to isolates of M. catarrhalis are also presented, suggesting a potential role as a diagnostic marker. To our knowledge, this is the first report demonstrating that M. catarrhalis expresses an Hb-binding protein and that this bacterium can utilize Hb as a sole iron source for growth.
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Affiliation(s)
- Kristin Furano
- Witebsky Center for Microbial Pathogenesis and Immunology, State University of New York at Buffalo, Buffalo, NY 14214, USA
- Department of Microbiology and Immunology, State University of New York at Buffalo, Buffalo, NY 14214, USA
| | - Nicole R Luke
- Witebsky Center for Microbial Pathogenesis and Immunology, State University of New York at Buffalo, Buffalo, NY 14214, USA
- Department of Microbiology and Immunology, State University of New York at Buffalo, Buffalo, NY 14214, USA
| | - Amy J Howlett
- Witebsky Center for Microbial Pathogenesis and Immunology, State University of New York at Buffalo, Buffalo, NY 14214, USA
- Department of Microbiology and Immunology, State University of New York at Buffalo, Buffalo, NY 14214, USA
| | - Anthony A Campagnari
- Division of Infectious Diseases, Department of Medicine, State University of New York at Buffalo, Buffalo, NY 14214, USA
- Witebsky Center for Microbial Pathogenesis and Immunology, State University of New York at Buffalo, Buffalo, NY 14214, USA
- Department of Microbiology and Immunology, State University of New York at Buffalo, Buffalo, NY 14214, USA
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90
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Oakhill JS, Sutton BJ, Gorringe AR, Evans RW. Homology modelling of transferrin-binding protein A from Neisseria meningitidis. Protein Eng Des Sel 2005; 18:221-8. [PMID: 15820975 DOI: 10.1093/protein/gzi024] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Neisseria meningitidis, a causative agent of bacterial meningitis, obtains transferrin-bound iron by expressing two outer membrane located transferrin-binding proteins, TbpA and TbpB. TbpA is thought to be an integral outer membrane pore that facilitates iron uptake. Evidence suggests that TbpA is a useful antigen for inclusion in a vaccine effective against meningococcal disease, hence the identification of regions involved in ligand binding is of paramount importance to design strategies to block uptake of iron. The protein shares sequence and functional similarities to the Escherichia coli siderophore receptors FepA and FhuA, whose structures have been determined. These receptors are composed of two domains, a 22-stranded beta-barrel and an N-terminal plug region that sits within the barrel and occludes the transmembrane pore. A three-dimensional TbpA model was constructed using FepA and FhuA structural templates, hydrophobicity analysis and homology modelling. TbpA was found to possess a similar architecture to the siderophore receptors. In addition to providing insights into the highly immunogenic nature of TbpA and allowing the prediction of potentially important ligand-binding epitopes, the model also reveals a narrow channel through its entire length. The relevance of this channel and the spatial arrangement of external loops, to the mechanism of iron translocation employed by TbpA is discussed.
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Affiliation(s)
- Jonathan S Oakhill
- Metalloprotein Research Group, Randall Division of Cell and Molecular Biophysics, King's College London, New Hunt's House, Guy's Campus, London SE1 1UL, UK
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91
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Stokes RH, Oakhill JS, Joannou CL, Gorringe AR, Evans RW. Meningococcal transferrin-binding proteins A and B show cooperation in their binding kinetics for human transferrin. Infect Immun 2005; 73:944-52. [PMID: 15664936 PMCID: PMC546982 DOI: 10.1128/iai.73.2.944-952.2005] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Neisseria meningitidis, a causative agent of bacterial meningitis and septicemia, obtains transferrin-bound iron by expressing two outer membrane-located transferrin-binding proteins, TbpA and TbpB. A novel system was developed to investigate the interaction between Tbps and human transferrin. Copurified TbpA-TbpB, recombined TbpA-TbpB, and individual TbpA and TbpB were reconstituted into liposomes and fused onto an HPA chip (BIAcore). All preparations formed stable monolayers, which, with the exception of TbpB, could be regenerated by removing bound transferrin. The ligand binding properties of these monolayers were characterized with surface plasmon resonance and shown to be specific for human transferrin. Kinetic data for diferric human transferrin binding showed that recombined TbpA-TbpB had K(a) and K(d) values similar to those of copurified TbpA-TbpB. Individual TbpA and TbpB also displayed K(a) values similar to those of copurified TbpA-TbpB, but their K(d) values were one order of magnitude higher. Chemical cross-linking studies revealed that TbpA and TbpB, in the absence of human transferrin, formed large complexes with TbpA as the predominant species. Upon human transferrin binding, a complex was formed with a molecular mass corresponding to that of a TbpB-human transferrin heterodimer as well as a higher-molecular-mass complex of this heterodimer cross-linked to TbpA. This indicates that TbpA and TbpB form a functional meningococcal receptor complex in which there is cooperativity in the human transferrin binding kinetics. However, iron loss from the diferric human transferrin-TbpA-TbpB complex was not greater than that from human transferrin alone, suggesting that additional meningococcal transport components are involved in the process of iron removal.
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Affiliation(s)
- Russell H Stokes
- Metalloprotein Research Group, Randall Division of Cell and Molecular Biophysics, GKT School of Biomedical Sciences, King's College London, Guy's Campus, New Hunt's House, London SE1 1UL, United Kingdom
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92
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Tom-Yew SAL, Cui DT, Bekker EG, Murphy MEP. Anion-independent Iron Coordination by the Campylobacter jejuni Ferric Binding Protein. J Biol Chem 2005; 280:9283-90. [PMID: 15613474 DOI: 10.1074/jbc.m412479200] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Campylobacter jejuni, the leading cause of human gastroenteritis, expresses a ferric binding protein (cFbpA) that in many pathogenic bacteria functions to acquire iron as part of their virulence repertoire. Recombinant cFbpA is isolated with ferric iron bound from Escherichia coli. The crystal structure of cFbpA reveals unprecedented iron coordination by only five protein ligands. The histidine and one tyrosine are derived from the N-terminal domain, whereas the three remaining tyrosine ligands are from the C-terminal domain. Surprisingly, a synergistic anion present in all other characterized ferric transport proteins is not observed in the cFbpA iron-binding site, suggesting a novel role for this protein in iron uptake. Furthermore, cFbpA is shown to bind iron with high affinity similar to Neisserial FbpA and exhibits an unusual preference for ferrous iron (oxidized subsequently to the ferric form) or ferric iron chelated by oxalate. Sequence and structure analyses reveal that cFbpA is a member of a new class of ferric binding proteins that includes homologs from invasive and intracellular bacteria as well as cyanobacteria. Overall, six classes are defined based on clustering within the tree and by their putative iron coordination. The absence of a synergistic anion in the iron coordination sphere of cFbpA also suggests an alternative model of evolution for FbpA homologs involving an early iron-binding ancestor instead of a requirement for a preexisting anion-binding ancestor.
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Affiliation(s)
- Stacey A L Tom-Yew
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
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93
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Abstract
Meningococcal disease is one of the most feared and serious infections in the young and its prevention by vaccination is an important goal. The high degree of antigenic variability of the organism makes the meningococcus a challenging target for vaccine prevention. Meningococcal polysaccharide vaccines against serogroup A and C are efficacious and have been widely used, often in combination with serogroup Y and W135 components. Their relative lack of immunogenicity in young children and infants can be overcome by conjugation to a protein carrier. The effectiveness of serogroup C glycoconjugate vaccines in children of all ages has been demonstrated and they have now been introduced into routine vaccination schedules. Conjugate vaccines against other serogroups, including A, Y, and W135 will soon be available and it is hoped they may emulate this success. Prevention of serogroup B disease has proven more elusive. Several serogroup B vaccines based on outer membrane vesicles have been shown to be immunogenic and reasonably effective in adults and older children, but the protection offered by them is chiefly strain-specific. Multivalent recombinant PorA vaccines have been developed to broaden the protective effect, but no efficacy data are available as yet. Intensive efforts have been directed at other outer membrane protein vaccine candidates and lipopolysaccharide, and some of these have been shown to offer protection in experimental animal models. Nonpathogenic Neisseriae spp. such as Neisseria lactamica are also possible vaccine candidates. Previously unknown proteins have been identified from in silico analysis of the meningococcal genome and their vaccine potential explored. However, none of these has yet been presented as the 'universal' protective antigen and work in this field continues to be held back by our limited knowledge concerning the mechanisms of natural protection against serogroup B meningococci.
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Affiliation(s)
- Jens U Rüggeberg
- Department of Child Health and Vaccine Institute, St George's Hospital Medical School, London, UK
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94
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95
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Shouldice SR, McRee DE, Dougan DR, Tari LW, Schryvers AB. Novel anion-independent iron coordination by members of a third class of bacterial periplasmic ferric ion-binding proteins. J Biol Chem 2004; 280:5820-7. [PMID: 15576371 DOI: 10.1074/jbc.m411238200] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The uptake of the element iron is vital for the survival of most organisms. Numerous pathogenic Gram-negative bacteria utilize a periplasm-to-cytosol ATP-binding cassette transport pathway to transport this essential atom in to the cell. In this study, we investigated the Yersinia enterocolitica (YfuA) and Serratia marcescens (SfuA) iron-binding periplasmic proteins. We have determined the 1.8-angstroms structures of iron-loaded (YfuA) and iron-free (SfuA) forms of this class of proteins. Although the sequence of these proteins varies considerably from the other members of the transferrin structural superfamily, they adopt the same three-dimensional fold. The iron-loaded YfuA structure illustrates the unique nature of this new class of proteins in that they are able to octahedrally coordinate the ferric ion in the absence of a bound anion. The iron-free SfuA structure contains a bound citrate anion in the iron-binding cleft that tethers the N- and C-terminal domains of the apo protein and stabilizes the partially open structure.
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Affiliation(s)
- Stephen R Shouldice
- Department of Microbiology and Infectious Diseases, University of Calgary, Calgary, Alberta T2N 4N1, Canada
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96
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Prochazkova K, Osicka R, Linhartova I, Halada P, Sulc M, Sebo P. The Neisseria meningitidis outer membrane lipoprotein FrpD binds the RTX protein FrpC. J Biol Chem 2004; 280:3251-8. [PMID: 15525636 DOI: 10.1074/jbc.m411232200] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
At conditions of low iron availability, Neisseria meningitidis produces a family of FrpC-like, type I-secreted RTX proteins of unknown role in meningococcal lifestyle. It is shown here that iron starvation also induces production of FrpD, the other protein expressed from a gene located immediately upstream of the frpC gene in a predicted iron-regulated frpDC operon. We found that FrpD is highly conserved in a set of meningococcal strains representative of all serogroups and does not exhibit any similarity to known sequences of other organisms. Subcellular localization and [3H]palmitic acid labeling in Escherichia coli revealed that FrpD is synthesized with a type II signal peptide for export across the cytoplasmic membrane and is, upon processing to a lipoprotein, sorted to the outer bacterial membrane. Furthermore, the biological function of FrpD appears to be linked to that of the RTX protein FrpC, because FrpD was found to bind the amino-proximal portion of FrpC (first 300 residues) with very high affinity (apparent Kd approximately 0.2 nM). These results suggest that FrpD represents an rtx loci-encoded accessory lipoprotein that could be involved in anchoring of the secreted RTX protein to the outer bacterial membrane.
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Affiliation(s)
- Katerina Prochazkova
- Institute of Microbiology of the Academy of Sciences of the Czech Republic, Videnska 1083, CZ-142 20 Prague 4, Czech Republic
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97
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Larson JA, Howie HL, So M. Neisseria meningitidis accelerates ferritin degradation in host epithelial cells to yield an essential iron source. Mol Microbiol 2004; 53:807-20. [PMID: 15255894 DOI: 10.1111/j.1365-2958.2004.04169.x] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
In order to colonize humans and cause disease, pathogenic bacteria must assimilate iron from their host. The vast majority of non-haem iron in humans is localized intracellularly, within the storage molecule ferritin. Despite the vast reserves of iron within ferritin, no pathogen has been demonstrated previously to exploit this molecule as an iron source. Here, we show that the Gram-negative diplococcus Neisseria meningitidis can trigger rapid redistribution and degradation of cytosolic ferritin within infected epithelial cells. Indirect immunofluorescence microscopy revealed that cytosolic ferritin is aggregated and recruited to intracellular meningococci (MC). The half-life of ferritin within cultured epithelial cells was found to decrease from 20.1 to 5.3 h upon infection with MC. Supplementation of infected epithelial cells with ascorbic acid abolished ferritin redistribution and degradation and prevented intracellular MC from replicating. The lysosomal protease inhibitor leupeptin slowed ferritin turnover and also retarded MC replication. Our laboratory has shown recently that MC can interfere with transferrin uptake by infected cells (Bonnah R.A., et al., 2000, Cell Microbiol 2: 207-218) and that, perhaps as a result, the infected cells have a transcriptional profile indicative of iron starvation (Bonnah, R.A., et al., 2004, Cell Microbiol 6: 473-484). In view of these findings, we suggest that accelerated ferritin degradation occurs as a response to an iron starvation state induced by MC infection and that ferritin degradation provides intracellular MC with a critical source of iron.
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Affiliation(s)
- Jason A Larson
- Department of Molecular Microbiology and Immunology, Oregon Health and Science University, Portland, OR 97239, USA.
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98
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Anderson DS, Adhikari P, Nowalk AJ, Chen CY, Mietzner TA. The hFbpABC transporter from Haemophilus influenzae functions as a binding-protein-dependent ABC transporter with high specificity and affinity for ferric iron. J Bacteriol 2004; 186:6220-9. [PMID: 15342592 PMCID: PMC515168 DOI: 10.1128/jb.186.18.6220-6229.2004] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2004] [Accepted: 06/09/2004] [Indexed: 11/20/2022] Open
Abstract
Pathogenic Haemophilus influenzae, Neisseria spp. (Neisseria gonorrhoeae and N. meningitidis), Serratia marcescens, and other gram-negative bacteria utilize a periplasm-to-cytosol FbpABC iron transporter. In this study, we investigated the H. influenzae FbpABC transporter in a siderophore-deficient Escherichia coli background to assess biochemical aspects of FbpABC transporter function. Using a radiolabeled Fe3+ transport assay, we established an apparent Km=0.9 microM and Vmax=1.8 pmol/10(7)cells/min for FbpABC-mediated transport. Complementation experiments showed that hFbpABC is dependent on the FbpA binding protein for transport. The ATPase inhibitor sodium orthovanadate demonstrated dose-dependent inhibition of FbpABC transport, while the protonmotive-force-inhibitor carbonyl cyanide m-chlorophenyl hydrazone had no effect. Metal competition experiments demonstrated that the transporter has high specificity for Fe3+ and selectivity for trivalent metals, including Ga3+ and Al3+, over divalent metals. Metal sensitivity experiments showed that several divalent metals, including copper, nickel, and zinc, exhibited general toxicity towards E. coli. Significantly, gallium-induced toxicity was specific only to E. coli expressing FbpABC. A single-amino-acid mutation in the gene encoding the periplasmic binding protein, FbpA(Y196I), resulted in a greatly diminished iron binding affinity Kd=5.2 x 10(-4) M(-1), approximately 14 orders of magnitude weaker than that of the wild-type protein. Surprisingly, the mutant transporter [FbpA(Y196I)BC] exhibited substantial transport activity, approximately 35% of wild-type transport, with Km=1.2 microM and Vmax=0.5 pmol/10(7)cells/min. We conclude that the FbpABC complexes possess basic characteristics representative of the family of bacterial binding protein-dependent ABC transporters. However, the specificity and high-affinity binding characteristics suggest that the FbpABC transporters function as specialized transporters satisfying the strict chemical requirements of ferric iron (Fe3+) binding and membrane transport.
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Affiliation(s)
- Damon S Anderson
- Department of Molecular Genetics and Biochemistry, University of Pittsburgh School of Medicine, Room E1240 Biomedical Science Tower, Lothrop St., Pittsburgh, PA 15261, USA
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99
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Abstract
During periods of endemic disease, about 10 % of the general population harbour Neisseria meningitidis in the nasopharynx. Since N. meningitidis is a strict human pathogen and most patients have not been in contact with other cases, asymptomatic carriers are presumably the major source of the pathogenic strains. Most carrier isolates are shown to lack capsule production. The capsule deficient state of meningococcal strains in the nasopharynx may aid evasion of the human immune defence and hence be selected to survive nasopharyngeal colonization. Carriage itself can be an immunizing process resulting in systemic protective antibody responses. Frequent nasopharyngeal colonization with related bacteria like Neisseria lactamica improves natural immunity to meningococci by the formation of cross-reacting antibodies. While most meningococcal strains recovered from patients belong to a limited number of clonal groups worldwide, strains isolated from carriers comprise numerous genotypes, with only a small proportion of the strains representing invasive clones. During the carriage state, co-colonization with other pathogenic and non-pathogenic bacteria may lead to genetic exchange, which may result in the emergence of new meningococcal clones. The high diversity of meningococcal carrier strains, compared with hypervirulent strains, supports the idea that transmissibility, not invasion, is essential in the life cycle of N. meningitidis.
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Affiliation(s)
- Siamak P Yazdankhah
- Department of Airborne Infections, Division of Infectious Disease Control, Norwegian Institute of Public Health, PO Box 4404 Nydalen, NO-0403 Oslo, Norway 2Department of Oral Biology, University of Oslo, Oslo, Norway
| | - Dominique A Caugant
- Department of Airborne Infections, Division of Infectious Disease Control, Norwegian Institute of Public Health, PO Box 4404 Nydalen, NO-0403 Oslo, Norway 2Department of Oral Biology, University of Oslo, Oslo, Norway
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Schalk IJ, Yue WW, Buchanan SK. Recognition of iron-free siderophores by TonB-dependent iron transporters. Mol Microbiol 2004; 54:14-22. [PMID: 15458401 DOI: 10.1111/j.1365-2958.2004.04241.x] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
TonB-dependent iron transporters reside in the outer membranes of Gram-negative bacteria, transporting ferric-complexes into the periplasm by a mechanism requiring proton motive force and an integral inner membrane complex, TonB-ExbB-ExbD. Certain TonB-dependent transporters contain an additional domain at the N-terminus, which interacts with an inner membrane regulatory protein and a cytoplasmic sigma factor to induce transcription of iron transport genes when a ferric-ligand is bound at the extracellular surface of the transporter. Transport of the ferric-ligand is apparently not necessary for transcription induction. Recent biophysical and crystallographic experiments have shown that this subclass of TonB-dependent iron transporters can bind iron-free ligands, whereas only the ferric-ligands are transported into the periplasm. This review focuses on the ligand binding properties of these transporters and includes a discussion of the biological function of the additional domain, the mechanism of transcription induction and the mechanism of ferric-ligand transport.
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Affiliation(s)
- Isabelle J Schalk
- Département des Récepteurs et Protéines Membranaires, UPR 9050, CNRS, ESBS, Bld Sébastien Brant, F-67 400 Illkirch, Strasbourg, France.
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