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Ntui CM, Fleckenstein JM, Schubert WD. Structural and biophysical characterization of the secreted, β-helical adhesin EtpA of Enterotoxigenic Escherichia coli. PLoS One 2023; 18:e0287100. [PMID: 37343026 PMCID: PMC10284417 DOI: 10.1371/journal.pone.0287100] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Accepted: 05/30/2023] [Indexed: 06/23/2023] Open
Abstract
Enterotoxigenic Escherichia coli (ETEC) is a diarrhoeal pathogen associated with high morbidity and mortality especially among young children in developing countries. At present, there is no vaccine for ETEC. One candidate vaccine antigen, EtpA, is a conserved secreted adhesin that binds to the tips of flagellae to bridge ETEC to host intestinal glycans. EtpA is exported through a Gram-negative, two-partner secretion system (TPSS, type Vb) comprised of the secreted EtpA passenger (TpsA) protein and EtpB (TpsB) transporter that is integrated into the outer bacterial membrane. TpsA proteins share a conserved, N-terminal TPS domain followed by an extensive C-terminal domain with divergent sequence repeats. Two soluble, N-terminal constructs of EtpA were prepared and analysed respectively including residues 67 to 447 (EtpA67-447) and 1 to 606 (EtpA1-606). The crystal structure of EtpA67-447 solved at 1.76 Å resolution revealed a right-handed parallel β-helix with two extra-helical hairpins and an N-terminal β-strand cap. Analyses by circular dichroism spectroscopy confirmed the β-helical fold and indicated high resistance to chemical and thermal denaturation as well as rapid refolding. A theoretical AlphaFold model of full-length EtpA largely concurs with the crystal structure adding an extended β-helical C-terminal domain after an interdomain kink. We propose that robust folding of the TPS domain upon secretion provides a template to extend the N-terminal β-helix into the C-terminal domains of TpsA proteins.
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Affiliation(s)
- Clifford Manyo Ntui
- Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria, South Africa
| | - James M. Fleckenstein
- Department of Medicine, Division of Infectious Diseases Washington University in Saint Louis, School of Medicine, Saint Louis, Missouri, United States of Ameirca
- Infectious Disease Service Saint Louis VA Health Care System, Saint Louis, Missouri, United States of Ameirca
| | - Wolf-Dieter Schubert
- Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria, South Africa
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A novel strategy for designing the antioxidant and adhesive bifunctional protein using the Lactobacillus strain-derived LPxTG motif structure. Process Biochem 2023. [DOI: 10.1016/j.procbio.2023.01.019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
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3
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The long and the short of Periscope Proteins. Biochem Soc Trans 2022; 50:1293-1302. [PMID: 36196877 DOI: 10.1042/bst20220194] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2022] [Revised: 09/10/2022] [Accepted: 09/13/2022] [Indexed: 11/17/2022]
Abstract
Bacteria sense, interact with, and modify their environmental niche by deploying a molecular ensemble at the cell surface. The changeability of this exposed interface, combined with extreme changes in the functional repertoire associated with lifestyle switches from planktonic to adherent and biofilm states necessitate dynamic variability. Dynamic surface changes include chemical modifications to the cell wall; export of diverse extracellular biofilm components; and modulation of expression of cell surface proteins for adhesion, co-aggregation and virulence. Local enrichment for highly repetitive proteins with high tandem repeat identity has been an enigmatic phenomenon observed in diverse bacterial species. Preliminary observations over decades of research suggested these repeat regions were hypervariable, as highly related strains appeared to express homologues with diverse molecular mass. Long-read sequencing data have been interrogated to reveal variation in repeat number; in combination with structural, biophysical and molecular dynamics approaches, the Periscope Protein class has been defined for cell surface attached proteins that dynamically expand and contract tandem repeat tracts at the population level. Here, I review the diverse high-stability protein folds and coherent interdomain linkages culminating in the formation of highly anisotropic linear repeat arrays, so-called rod-like protein 'stalks', supporting roles in bacterial adhesion, biofilm formation, cell surface spatial competition, and immune system modulation. An understanding of the functional impacts of dynamic changes in repeat arrays and broader characterisation of the unusual protein folds underpinning this variability will help with the design of immunisation strategies, and contribute to synthetic biology approaches including protein engineering and microbial consortia construction.
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C-protein α-antigen modulates the lantibiotic thusin resistance in Streptococcus agalactiae. Antonie van Leeuwenhoek 2021; 114:1595-1607. [PMID: 34319449 DOI: 10.1007/s10482-021-01626-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2021] [Accepted: 07/19/2021] [Indexed: 10/20/2022]
Abstract
Screening for producers of potent antimicrobial peptides, resulted in the isolation of Bacillus cereus BGNM1 with strong antimicrobial activity against Listeria monocytogenes. Genome sequence analysis revealed that BGNM1 contains the gene cluster associated with the production of the lantibiotic, thusin, previously identified in B. thuringiensis. Purification of the antimicrobial activity confirmed that strain BGMN1 produces thusin. Both thusin sensitive and resistant strains were detected among clinical isolates of Streptococcus agalactiae. Random mutagenesis of a thusin sensitive strain, S. agalactiae B782, was performed in an attempt to identify the receptor protein for thusin. Three independent thusin resistant mutants were selected and their complete genomes sequenced. Comparative sequence analysis of these mutants with the WT strain revealed that duplication of a region encoding a 79 amino acids repeat in a C-protein α-antigen was a common difference, suggesting it to be responsible for increased resistance to thusin. Since induced thusin resistant mutants showed higher level of resistance than the naturally resistant B761 strain, complete genome sequencing of strain B761 was performed to check the integrity of the C-protein α-antigen-encoding gene. This analysis revealed that this gene is deleted in B761, providing further evidence that this protein promotes interaction of the thusin with receptor.
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Periscope Proteins are variable-length regulators of bacterial cell surface interactions. Proc Natl Acad Sci U S A 2021; 118:2101349118. [PMID: 34074781 PMCID: PMC8201768 DOI: 10.1073/pnas.2101349118] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
The structure of single and tandem SHIRT domains from the streptococcal surface protein Sgo_0707 were determined. In conjunction with biophysics and molecular dynamics simulations, the results show that the observed gene length variation would result in differential projection of the host ligand binding domain on the bacterial cell surface. An analysis of long-read DNA sequence data reveals many other repetitive bacterial surface proteins that appear to undergo gene length variation. We propose that these variable-length “Periscope Proteins” represent an important mechanism of bacterial cell surface modification with potential roles in infection and immune evasion. Changes at the cell surface enable bacteria to survive in dynamic environments, such as diverse niches of the human host. Here, we reveal “Periscope Proteins” as a widespread mechanism of bacterial surface alteration mediated through protein length variation. Tandem arrays of highly similar folded domains can form an elongated rod-like structure; thus, variation in the number of domains determines how far an N-terminal host ligand binding domain projects from the cell surface. Supported by newly available long-read genome sequencing data, we propose that this class could contain over 50 distinct proteins, including those implicated in host colonization and biofilm formation by human pathogens. In large multidomain proteins, sequence divergence between adjacent domains appears to reduce interdomain misfolding. Periscope Proteins break this “rule,” suggesting that their length variability plays an important role in regulating bacterial interactions with host surfaces, other bacteria, and the immune system.
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6
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Ahola HG, Sontag-Strohm TS, Schulman AH, Tanhuanpää P, Viitala S, Huang X. Immunochemical analysis of oat avenins in an oat cultivar and landrace collection. J Cereal Sci 2020. [DOI: 10.1016/j.jcs.2020.103053] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
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Eraso JM, Kachroo P, Olsen RJ, Beres SB, Zhu L, Badu T, Shannon S, Cantu CC, Saavedra MO, Kubiak SL, Porter AR, DeLeo FR, Musser JM. Genetic heterogeneity of the Spy1336/R28-Spy1337 virulence axis in Streptococcus pyogenes and effect on gene transcript levels and pathogenesis. PLoS One 2020; 15:e0229064. [PMID: 32214338 PMCID: PMC7098570 DOI: 10.1371/journal.pone.0229064] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Accepted: 01/28/2020] [Indexed: 12/20/2022] Open
Abstract
Streptococcus pyogenes is a strict human pathogen responsible for more than 700 million infections annually worldwide. Strains of serotype M28 S. pyogenes are typically among the five more abundant types causing invasive infections and pharyngitis in adults and children. Type M28 strains also have an unusual propensity to cause puerperal sepsis and neonatal disease. We recently discovered that a one-nucleotide indel in an intergenic homopolymeric tract located between genes Spy1336/R28 and Spy1337 altered virulence in a mouse model of infection. In the present study, we analyzed size variation in this homopolymeric tract and determined the extent of heterogeneity in the number of tandemly-repeated 79-amino acid domains in the coding region of Spy1336/R28 in large samples of strains recovered from humans with invasive infections. Both repeat sequence elements are highly polymorphic in natural populations of M28 strains. Variation in the homopolymeric tract results in (i) changes in transcript levels of Spy1336/R28 and Spy1337 in vitro, (ii) differences in virulence in a mouse model of necrotizing myositis, and (iii) global transcriptome changes as shown by RNAseq analysis of isogenic mutant strains. Variation in the number of tandem repeats in the coding sequence of Spy1336/R28 is responsible for size variation of R28 protein in natural populations. Isogenic mutant strains in which genes encoding R28 or transcriptional regulator Spy1337 are inactivated are significantly less virulent in a nonhuman primate model of necrotizing myositis. Our findings provide impetus for additional studies addressing the role of R28 and Spy1337 variation in pathogen-host interactions.
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Affiliation(s)
- Jesus M. Eraso
- Center for Molecular and Translational Human Infectious Diseases Research, Department of Pathology and Genomic Medicine, Houston Methodist Research Institute and Houston Methodist Hospital, Houston, Texas, United States of America
| | - Priyanka Kachroo
- Center for Molecular and Translational Human Infectious Diseases Research, Department of Pathology and Genomic Medicine, Houston Methodist Research Institute and Houston Methodist Hospital, Houston, Texas, United States of America
| | - Randall J. Olsen
- Center for Molecular and Translational Human Infectious Diseases Research, Department of Pathology and Genomic Medicine, Houston Methodist Research Institute and Houston Methodist Hospital, Houston, Texas, United States of America
- Departments of Pathology and Laboratory Medicine and Microbiology and Immunology, Weill Cornell Medical College, New York, New York, United States of America
| | - Stephen B. Beres
- Center for Molecular and Translational Human Infectious Diseases Research, Department of Pathology and Genomic Medicine, Houston Methodist Research Institute and Houston Methodist Hospital, Houston, Texas, United States of America
| | - Luchang Zhu
- Center for Molecular and Translational Human Infectious Diseases Research, Department of Pathology and Genomic Medicine, Houston Methodist Research Institute and Houston Methodist Hospital, Houston, Texas, United States of America
| | - Traci Badu
- Center for Molecular and Translational Human Infectious Diseases Research, Department of Pathology and Genomic Medicine, Houston Methodist Research Institute and Houston Methodist Hospital, Houston, Texas, United States of America
| | - Sydney Shannon
- Center for Molecular and Translational Human Infectious Diseases Research, Department of Pathology and Genomic Medicine, Houston Methodist Research Institute and Houston Methodist Hospital, Houston, Texas, United States of America
| | - Concepcion C. Cantu
- Center for Molecular and Translational Human Infectious Diseases Research, Department of Pathology and Genomic Medicine, Houston Methodist Research Institute and Houston Methodist Hospital, Houston, Texas, United States of America
| | - Matthew Ojeda Saavedra
- Center for Molecular and Translational Human Infectious Diseases Research, Department of Pathology and Genomic Medicine, Houston Methodist Research Institute and Houston Methodist Hospital, Houston, Texas, United States of America
| | - Samantha L. Kubiak
- Center for Molecular and Translational Human Infectious Diseases Research, Department of Pathology and Genomic Medicine, Houston Methodist Research Institute and Houston Methodist Hospital, Houston, Texas, United States of America
| | - Adeline R. Porter
- Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, United States of America
| | - Frank R. DeLeo
- Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, United States of America
| | - James M. Musser
- Center for Molecular and Translational Human Infectious Diseases Research, Department of Pathology and Genomic Medicine, Houston Methodist Research Institute and Houston Methodist Hospital, Houston, Texas, United States of America
- Departments of Pathology and Laboratory Medicine and Microbiology and Immunology, Weill Cornell Medical College, New York, New York, United States of America
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Whelan F, Lafita A, Griffiths SC, Cooper REM, Whittingham JL, Turkenburg JP, Manfield IW, St. John AN, Paci E, Bateman A, Potts JR. Defining the remarkable structural malleability of a bacterial surface protein Rib domain implicated in infection. Proc Natl Acad Sci U S A 2019; 116:26540-26548. [PMID: 31818940 PMCID: PMC6936399 DOI: 10.1073/pnas.1911776116] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Streptococcus groups A and B cause serious infections, including early onset sepsis and meningitis in newborns. Rib domain-containing surface proteins are found associated with invasive strains and elicit protective immunity in animal models. Yet, despite their apparent importance in infection, the structure of the Rib domain was previously unknown. Structures of single Rib domains of differing length reveal a rare case of domain atrophy through deletion of 2 core antiparallel strands, resulting in the loss of an entire sheet of the β-sandwich from an immunoglobulin-like fold. Previously, observed variation in the number of Rib domains within these bacterial cell wall-attached proteins has been suggested as a mechanism of immune evasion. Here, the structure of tandem domains, combined with molecular dynamics simulations and small angle X-ray scattering, suggests that variability in Rib domain number would result in differential projection of an N-terminal host-colonization domain from the bacterial surface. The identification of 2 further structures where the typical B-D-E immunoglobulin β-sheet is replaced with an α-helix further confirms the extensive structural malleability of the Rib domain.
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Affiliation(s)
- Fiona Whelan
- Department of Biology, The University of York, YO10 5DD York, United Kingdom
| | - Aleix Lafita
- European Molecular Biology Laboratory, European Bioinformatics Institute, CB10 1SD Hinxton, United Kingdom
| | - Samuel C. Griffiths
- Department of Biology, The University of York, YO10 5DD York, United Kingdom
| | | | - Jean L. Whittingham
- York Structural Biology Laboratory, Department of Chemistry, The University of York, YO10 5DD York, United Kingdom
| | - Johan P. Turkenburg
- York Structural Biology Laboratory, Department of Chemistry, The University of York, YO10 5DD York, United Kingdom
| | - Iain W. Manfield
- Astbury Centre for Structural Molecular Biology, The University of Leeds, LS2 9JT Leeds, United Kingdom
| | - Alexander N. St. John
- Astbury Centre for Structural Molecular Biology, The University of Leeds, LS2 9JT Leeds, United Kingdom
| | - Emanuele Paci
- Astbury Centre for Structural Molecular Biology, The University of Leeds, LS2 9JT Leeds, United Kingdom
| | - Alex Bateman
- European Molecular Biology Laboratory, European Bioinformatics Institute, CB10 1SD Hinxton, United Kingdom
| | - Jennifer R. Potts
- Department of Biology, The University of York, YO10 5DD York, United Kingdom
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9
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Abstract
The surface of the Gram-positive opportunistic pathogen Streptococcus agalactiae, or group B Streptococcus (GBS), harbors several carbohydrate and protein antigens with the potential to be effective vaccines. Capsular polysaccharides of all clinically-relevant GBS serotypes coupled to immunogenic proteins of both GBS and non-GBS origin have undergone extensive testing in animals that led to advanced clinical trials in healthy adult women. In addition, GBS proteins either alone or in combination have been tested in animals; a fusion protein construct has recently advanced to human clinical studies. Given our current understanding of the antigenicity and immunogenicity of the wide array of GBS surface antigens, formulations now exist for the generation of viable vaccines against diseases caused by GBS.
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Faria M, Bordin N, Kizina J, Harder J, Devos D, Lage OM. Planctomycetes attached to algal surfaces: Insight into their genomes. Genomics 2018; 110:231-238. [PMID: 29074368 DOI: 10.1016/j.ygeno.2017.10.007] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2017] [Revised: 10/06/2017] [Accepted: 10/21/2017] [Indexed: 01/03/2023]
Abstract
Planctomycetes are bacteria with complex molecular and cellular biology. They have large genomes, some over 7Mb, and complex life cycles that include motile cells and sessile cells. Some live on the complex biofilm of macroalgae. Factors governing their life in this environment were investigated at the genomic level. We analyzed the genomes of three planctomycetes isolated from algal surfaces. The genomes were 6.6Mbp to 8.1Mbp large. Genes for outer-membrane proteins, peptidoglycan and lipopolysaccharide biosynthesis were present. Rubripirellula obstinata LF1T, Roseimaritima ulvae UC8T and Mariniblastus fucicola FC18T shared with Rhodopirellula baltica and R. rubra SWK7 unique proteins related to metal binding systems, phosphate metabolism, chemotaxis, and stress response. These functions may contribute to their ecological success in such a complex environment. Exceptionally huge proteins (6000 to 10,000 amino-acids) with extracellular, periplasmic or membrane-associated locations were found which may be involved in biofilm formation or cell adhesion.
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Affiliation(s)
- Mafalda Faria
- Departamento de Biologia, Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre s/n, 4169-007 Porto, Portugal
| | - Nicola Bordin
- Centro Andaluz de Biología del Desarollo, CSIC, Junta de Andalucía, Universidad Pablo de Olavide, Carretera de Utrera, Km. 1, 41013 Seville, Spain
| | - Jana Kizina
- Max Planck Institute for Marine Microbiology, Celsiusstrasse 1, D-28359 Bremen, Germany
| | - Jens Harder
- Max Planck Institute for Marine Microbiology, Celsiusstrasse 1, D-28359 Bremen, Germany
| | - Damien Devos
- Centro Andaluz de Biología del Desarollo, CSIC, Junta de Andalucía, Universidad Pablo de Olavide, Carretera de Utrera, Km. 1, 41013 Seville, Spain
| | - Olga M Lage
- Departamento de Biologia, Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre s/n, 4169-007 Porto, Portugal; CIMAR/CIIMAR - Centro Interdisciplinar de Investigação Marinha e Ambiental, Universidade do Porto, Terminal de Cruzeiros do Porto de Leixões, Av. General Norton de Matos s/n, 4450-208 Matosinhos, Portugal.
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Song JY, Lim JH, Lim S, Yong Z, Seo HS. Progress toward a group B streptococcal vaccine. Hum Vaccin Immunother 2018; 14:2669-2681. [PMID: 29995578 PMCID: PMC6314413 DOI: 10.1080/21645515.2018.1493326] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Revised: 05/18/2018] [Accepted: 06/19/2018] [Indexed: 01/31/2023] Open
Abstract
Streptococcus agalactiae (group B Streptococcus, GBS) is a leading cause of severe invasive disease in neonate, elderly, and immunocompromised patients worldwide. Despite recent advances in the diagnosis and intrapartum antibiotic prophylaxis (IAP) of GBS infections, it remains one of the most common causes of neonatal morbidity and mortality, causing serious infections. Furthermore, recent studies reported an increasing number of GBS infections in pregnant women and elderly. Although IAP is effective, it has several limitations, including increasing antimicrobial resistance and late GBS infection after negative antenatal screening. Maternal immunization is the most promising and effective countermeasure against GBS infection in neonates. However, no vaccine is available to date, but two types of vaccines, protein subunit and capsular polysaccharide conjugate vaccines, were investigated in clinical trials. Here, we provide an overview of the GBS vaccine development status and recent advances in the development of immunoassays to evaluate the GBS vaccine clinical efficacy.
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Affiliation(s)
- Joon Young Song
- Department of Internal Medicine, Korea University College of Medicine, Seoul, Republic of Korea
| | - Jae Hyang Lim
- Department of Microbiology, College of Medicine, Ewha Womans University, Seoul, Republic of Korea
| | - Sangyong Lim
- Biotechnology Division, Korea Atomic Energy Research Institute, Jeongeup, Republic of Korea
- Department of Radiation Biotechnology and Applied Radioisotope Science, University of Science and Technology, Daejeon, Republic of Korea
| | - Zhi Yong
- Biotechnology Division, Korea Atomic Energy Research Institute, Jeongeup, Republic of Korea
- Department of Radiation Biotechnology and Applied Radioisotope Science, University of Science and Technology, Daejeon, Republic of Korea
| | - Ho Seong Seo
- Biotechnology Division, Korea Atomic Energy Research Institute, Jeongeup, Republic of Korea
- Department of Radiation Biotechnology and Applied Radioisotope Science, University of Science and Technology, Daejeon, Republic of Korea
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Survey of immunological features of the alpha-like proteins of Streptococcus agalactiae. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2014; 22:153-9. [PMID: 25540270 DOI: 10.1128/cvi.00643-14] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Nearly all Streptococcus agalactiae (group B streptococcus [GBS]) strains express a protein which belongs to the so-called alpha-like proteins (Alps), of which Cα, Alp1, Alp2, Alp3, Rib, and Alp4 are known to occur in GBS. The Alps are chimeras which form mosaic structures on the GBS surface. Both N- and C-terminal stretches of the Alps possess immunogenic sites of dissimilar immunological specificity. In this review, we have compiled data dealing with the specificity of the N- and C-terminal immunogenic sites of the Alps. The majority of N-terminal sites show protein specificity while the C-terminal sites show broader cross-reactivity. Molecular serotyping has revealed that antibody-based serotyping has often resulted in erroneous Alp identification, due to persistence of cross-reacting antibodies in antisera for serotyping. Retrospectively, this could be expected on the basis of sequence analysis results. Some of the historical R proteins are in fact Alps. The data included in the review may provide a basis for decisions regarding techniques for the preparation of specific antisera for serotyping of GBS, for use in other approaches in GBS research, and for decision making in the context of GBS vaccine developments.
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Abstract
Streptococcus agalactiae (Group B streptococcus) is an important cause of disease in infants, pregnant women, the elderly and in immunosuppressed adults. An effective vaccine is likely to prevent the majority of infant disease (both early and late onset), as well as Group B streptococcus-related stillbirths and prematurity, to avoid the current real and theoretical limitations of intrapartum antibiotic prophylaxis, and to be cost effective. The optimal time to administer such a vaccine would be in the third trimester of pregnancy. The main limitations on the production of a Group B streptococcus vaccine are not technical or scientific, but regulatory and legal. A number of candidates including capsular conjugate vaccines using traditional carrier proteins such as tetanus toxoid and mutant diphtheria toxin CRM197, as well as Group B streptococcus-specific proteins such as C5a peptidase, protein vaccines using one or more Group B streptococcus surface proteins and mucosal vaccines, have the potential to be successful vaccines. The capsular conjugate vaccines using tetanus and CRM197 carrier proteins are the most advanced candidates, having already completed Phase II human studies including use in the target population of pregnant women (tetanus toxoid conjugate), however, no definitive protein conjugates have yet been trialed. However, unless the regulatory environment is changed specifically to allow the development of a Group B streptococcus vaccine, it is unlikely that one will ever reach the market.
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Affiliation(s)
- Paul T Heath
- Department of Child Health and Vaccine Institute, St George's Hospital Medical School, London, UK.
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14
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Zhou K, Aertsen A, Michiels CW. The role of variable DNA tandem repeats in bacterial adaptation. FEMS Microbiol Rev 2013; 38:119-41. [PMID: 23927439 DOI: 10.1111/1574-6976.12036] [Citation(s) in RCA: 105] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2013] [Revised: 07/13/2013] [Accepted: 07/26/2013] [Indexed: 01/05/2023] Open
Abstract
DNA tandem repeats (TRs), also designated as satellite DNA, are inter- or intragenic nucleotide sequences that are repeated two or more times in a head-to-tail manner. Because TR tracts are prone to strand-slippage replication and recombination events that cause the TR copy number to increase or decrease, loci containing TRs are hypermutable. An increasing number of examples illustrate that bacteria can exploit this instability of TRs to reversibly shut down or modulate the function of specific genes, allowing them to adapt to changing environments on short evolutionary time scales without an increased overall mutation rate. In this review, we discuss the prevalence and distribution of inter- and intragenic TRs in bacteria and the mechanisms of their instability. In addition, we review evidence demonstrating a role of TR variations in bacterial adaptation strategies, ranging from immune evasion and tissue tropism to the modulation of environmental stress tolerance. Nevertheless, while bioinformatic analysis reveals that most bacterial genomes contain a few up to several dozens of intra- and intergenic TRs, only a small fraction of these have been functionally studied to date.
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Affiliation(s)
- Kai Zhou
- Department of Microbial and Molecular Systems (M²S), Faculty of Bioscience Engineering, Laboratory of Food Microbiology and Leuven Food Science and Nutrition Research Centre (LFoRCe), KU Leuven, Leuven, Belgium
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15
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Protein domain repetition is enriched in Streptococcal cell-surface proteins. Genomics 2012; 100:370-9. [PMID: 22921469 DOI: 10.1016/j.ygeno.2012.08.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2012] [Revised: 08/02/2012] [Accepted: 08/07/2012] [Indexed: 11/20/2022]
Abstract
Tandem repetition of domain in protein sequence occurs in all three domains of life. It creates protein diversity and adds functional complexity in organisms. In this work, we analyzed 52 streptococcal genomes and found 3748 proteins contained domain repeats. Proteins not harboring domain repeats are significantly enriched in cytoplasm, whereas proteins with domain repeats are significantly enriched in cytoplasmic membrane, cell wall and extracellular locations. Domain repetition occurs most frequently in S. pneumoniae and least in S. thermophilus and S. pyogenes. DUF1542 is the highest repeated domain in a single protein, followed by Rib, CW_binding_1, G5 and HemolysinCabind. 3D structures of 24 repeat-containing proteins were predicted to investigate the structural and functional effect of domain repetition. Several repeat-containing streptococcal cell surface proteins are known to be virulence-associated. Surface-associated tandem domain-containing proteins without experimental functional characterization may be potentially involved in the pathogenesis of streptococci and deserve further investigation.
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Ehrlichia chaffeensis TRP120 binds a G+C-rich motif in host cell DNA and exhibits eukaryotic transcriptional activator function. Infect Immun 2011; 79:4370-81. [PMID: 21859854 DOI: 10.1128/iai.05422-11] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Ehrlichia chaffeensis is an obligately intracellular bacterium that modulates host cell gene transcription in the mononuclear phagocyte, but the host gene targets and mechanisms involved in transcriptional modulation are not well-defined. In this study, we identified a novel tandem repeat DNA-binding domain in the E. chaffeensis 120-kDa tandem repeat protein (TRP120) that directly binds host cell DNA. TRP120 was observed by immunofluorescent microscopy in the nucleus of E. chaffeensis-infected host cells and was detected in nuclear extracts by Western immunoblotting with TRP120-specific antibody. The TRP120 binding sites and associated host cell target genes were identified using high-throughput deep sequencing (Illumina) of immunoprecipitated DNA (chromatin immunoprecipitation and high-throughput DNA sequencing). Multiple em motif elicitation (MEME) analysis of the most highly enriched TRP120-bound sequences revealed a G+C-rich DNA motif, and recombinant TRP120 specifically bound synthetic oligonucleotides containing the motif. TRP120 target gene binding sites were mapped most frequently to intersecting regions (intron/exon; 49%) but were also identified in upstream regulatory regions (25%) and downstream locations (26%). Genes targeted by TRP120 were most frequently associated with transcriptional regulation, signal transduction, and apoptosis. TRP120 targeted inflammatory chemokine genes, CCL2, CCL20, and CXCL11, which were strongly upregulated during E. chaffeensis infection and were also upregulated by direct transfection with recombinant TRP120. This study reveals that TRP120 is a novel DNA-binding protein that is involved in a host gene transcriptional regulation strategy.
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Molecular and cellular pathobiology of Ehrlichia infection: targets for new therapeutics and immunomodulation strategies. Expert Rev Mol Med 2011; 13:e3. [PMID: 21276277 DOI: 10.1017/s1462399410001730] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Ehrlichia are small obligately intracellular bacteria in the order Rickettsiales that are transmitted by ticks and associated with emerging life-threatening human zoonoses. Vaccines are not available for human ehrlichiosis, and therapeutic options are limited to a single antibiotic class. New technologies for exploring host-pathogen interactions have yielded recent advances in understanding the molecular interactions between Ehrlichia and the eukaryotic host cell and identified new targets for therapeutic and vaccine development, including those that target pathogen virulence mechanisms or disrupt the processes associated with ehrlichial effector proteins. Animal models have also provided insight into immunopathological mechanisms that contribute significantly to understanding severe disease manifestations, which should lead to the development of immunomodulatory approaches for treating patients nearing or experiencing severe disease states. In this review, we discuss the recent advances in our understanding of molecular and cellular pathobiology and the immunobiology of Ehrlichia infection. We identify new molecular host-pathogen interactions that can be targets of new therapeutics, and discuss prospects for treating the immunological dysregulation during acute infection that leads to life-threatening complications.
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18
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Calvo-Bado LA, Green LE, Medley GF, Ul-Hassan A, Grogono-Thomas R, Buller N, Kaler J, Russell CL, Kennan RM, Rood JI, Wellington EMH. Detection and diversity of a putative novel heterogeneous polymorphic proline-glycine repeat (Pgr) protein in the footrot pathogen Dichelobacter nodosus. Vet Microbiol 2011; 147:358-66. [PMID: 20655152 DOI: 10.1016/j.vetmic.2010.06.024] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2009] [Revised: 06/23/2010] [Accepted: 06/25/2010] [Indexed: 11/29/2022]
Abstract
Dichelobacter nodosus, a Gram-negative anaerobic bacterium, is the essential causative agent of footrot in sheep. Currently, depending on the clinical presentation in the field, footrot is described as benign or virulent; D. nodosus strains have also been classified as benign or virulent, but this designation is not always consistent with clinical disease. The aim of this study was to determine the diversity of the pgr gene, which encodes a putative proline-glycine repeat protein (Pgr). The pgr gene was present in all 100 isolates of D. nodosus that were examined and, based on sequence analysis had two variants, pgrA and pgrB. In pgrA, there were two coding tandem repeat regions, R1 and R2: different strains had variable numbers of repeats within these regions. The R1 and R2 were absent from pgrB. Both variants were present in strains from Australia, Sweden and the UK, however, only pgrB was detected in isolates from Western Australia. The pgrA gene was detected in D. nodosus from tissue samples from two flocks in the UK with virulent footrot and only pgrB from a flock with no virulent or benign footrot for >10 years. Bioinformatic analysis of the putative PgrA protein indicated that it contained a collagen-like cell surface anchor motif. These results suggest that the pgr gene may be a useful molecular marker for epidemiological studies.
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Affiliation(s)
- Leo A Calvo-Bado
- Department of Biological Sciences, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, UK.
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19
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20
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Adhesive activity of the haemophilus cryptic genospecies cha autotransporter is modulated by variation in tandem Peptide repeats. J Bacteriol 2010; 193:329-39. [PMID: 21037000 DOI: 10.1128/jb.00933-10] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The Haemophilus cryptic genospecies is an important cause of maternal genital tract and neonatal systemic infections and initiates infection by colonizing the genital or respiratory epithelium. In recent work, we identified a unique Haemophilus cryptic genospecies protein called Cha, which mediates efficient adherence to genital and respiratory epithelia. The Cha adhesin belongs to the trimeric autotransporter family and contains an N-terminal signal peptide, an internal passenger domain that harbors adhesive activity, and a C-terminal membrane anchor domain. The passenger domain in Cha contains clusters of YadA-like head domains and neck motifs as well as a series of tandem 28-amino-acid peptide repeats. In the current study, we report that variation in peptide repeat number gradually modulates Cha adhesive activity, associated with a direct effect on the length of Cha fibers on the bacterial cell surface. The N-terminal 404 residues of the Cha passenger domain mediate binding to host cells and also facilitate bacterial aggregation through intermolecular Cha-Cha binding. As the tandem peptide repeats expand, the Cha fiber becomes longer and Cha adherence activity decreases. The expansion and contraction of peptide repeats represent a novel mechanism for modulating adhesive capacity, potentially balancing the need of the organism to colonize the genital and respiratory tracts with the ability to attach to alternative substrates, disperse within the host, or evade the host immune system.
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21
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Nobbs AH, Lamont RJ, Jenkinson HF. Streptococcus adherence and colonization. Microbiol Mol Biol Rev 2009; 73:407-50, Table of Contents. [PMID: 19721085 PMCID: PMC2738137 DOI: 10.1128/mmbr.00014-09] [Citation(s) in RCA: 431] [Impact Index Per Article: 28.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Streptococci readily colonize mucosal tissues in the nasopharynx; the respiratory, gastrointestinal, and genitourinary tracts; and the skin. Each ecological niche presents a series of challenges to successful colonization with which streptococci have to contend. Some species exist in equilibrium with their host, neither stimulating nor submitting to immune defenses mounted against them. Most are either opportunistic or true pathogens responsible for diseases such as pharyngitis, tooth decay, necrotizing fasciitis, infective endocarditis, and meningitis. Part of the success of streptococci as colonizers is attributable to the spectrum of proteins expressed on their surfaces. Adhesins enable interactions with salivary, serum, and extracellular matrix components; host cells; and other microbes. This is the essential first step to colonization, the development of complex communities, and possible invasion of host tissues. The majority of streptococcal adhesins are anchored to the cell wall via a C-terminal LPxTz motif. Other proteins may be surface anchored through N-terminal lipid modifications, while the mechanism of cell wall associations for others remains unclear. Collectively, these surface-bound proteins provide Streptococcus species with a "coat of many colors," enabling multiple intimate contacts and interplays between the bacterial cell and the host. In vitro and in vivo studies have demonstrated direct roles for many streptococcal adhesins as colonization or virulence factors, making them attractive targets for therapeutic and preventive strategies against streptococcal infections. There is, therefore, much focus on applying increasingly advanced molecular techniques to determine the precise structures and functions of these proteins, and their regulatory pathways, so that more targeted approaches can be developed.
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Affiliation(s)
- Angela H Nobbs
- Oral Microbiology Unit, Department of Oral and Dental Science, University of Bristol, Bristol BS1 2LY, United Kingdom
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22
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Radtke A, Kong F, Bergh K, Lyng RV, Ko D, Gilbert GL. Identification of surface proteins of group B streptococci: serotyping versus genotyping. J Microbiol Methods 2009; 78:363-5. [PMID: 19573567 DOI: 10.1016/j.mimet.2009.06.017] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2009] [Revised: 06/22/2009] [Accepted: 06/23/2009] [Indexed: 11/30/2022]
Abstract
We compared serotyping to genotyping of group B streptococcal (GBS) surface proteins in 147 Australasian isolates. Results were concordant for the two methods in 73.8% of 122 isolates, discordant for three and partially discordant for 29 isolates. For the purpose of epidemiological typing of GBS, genotyping is superior to serotyping.
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Affiliation(s)
- Andreas Radtke
- Norwegian University of Science and Technology, Department of Laboratory Medicine, Children's and Women's Health, Trondheim, Norway.
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23
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Lactic acid is a potential virulence factor for group B Streptococcus. Microb Pathog 2009; 46:43-52. [DOI: 10.1016/j.micpath.2008.10.009] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2008] [Revised: 10/07/2008] [Accepted: 10/17/2008] [Indexed: 11/22/2022]
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24
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Harper KN, Liu H, Ocampo PS, Steiner BM, Martin A, Levert K, Wang D, Sutton M, Armelagos GJ. The sequence of the acidic repeat protein (arp) gene differentiates venereal from nonvenereal Treponema pallidum subspecies, and the gene has evolved under strong positive selection in the subspecies that causes syphilis. ACTA ACUST UNITED AC 2008; 53:322-32. [PMID: 18554302 DOI: 10.1111/j.1574-695x.2008.00427.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Despite the completion of the Treponema pallidum genome project, only minor genetic differences have been found between the subspecies that cause venereal syphilis (ssp. pallidum) and the nonvenereal diseases yaws (ssp. pertenue) and bejel (ssp. endemicum). In this paper, we describe sequence variation in the arp gene which allows straightforward differentiation of ssp. pallidum from the nonvenereal subspecies. We also present evidence that this region is subject to positive selection in ssp. pallidum, consistent with pressure from the immune system. Finally, the presence of multiple, but distinct, repeat motifs in both ssp. pallidum and Treponema paraluiscuniculi (the pathogen responsible for rabbit syphilis) suggests that a diverse repertoire of repeat motifs is associated with sexual transmission. This study suggests that variations in the number and sequence of repeat motifs in the arp gene have clinical, epidemiological, and evolutionary significance.
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Affiliation(s)
- Kristin N Harper
- Department of Population Biology, Ecology, and Evolution, Emory University, Atlanta, GA, USA
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25
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Hypervariations of a protease-encoding gene, PD0218 (pspB), in Xylella fastidiosa strains causing almond leaf scorch and Pierce's disease in California. Appl Environ Microbiol 2008; 74:3652-7. [PMID: 18456854 DOI: 10.1128/aem.02386-07] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Xylella fastidiosa is a gram-negative plant pathogenic bacterium that causes almond leaf scorch disease (ALSD) and Pierce's disease (PD) of grape in many regions of North America and Mexico. Of the two 16S rRNA gene genotypes described in California, A genotype strains cause ALSD only and G genotype strains cause both PD and ALSD. While G genotype strains cause two different diseases, little is known about their genetic variation. In this study, we identified a putative protease locus, PD0218 (pspB), in the genome of X. fastidiosa and evaluated the variation at this locus in X. fastidiosa populations. PD0218 contains tandem repeats of ACDCCA, translated to threonine and proline (TP), upstream of the putative protease conserved domain. Among 116 X. fastidiosa ALSD and PD strains isolated from seven locations in California, tandem repeat numbers (TRNs) varied from 9 to 47, with a total of 30 TRN genotypes, indicating that X. fastidiosa possesses an active mechanism for contracting and expanding tandem repeats at this locus. Significant TRN variation was found among PD strains (mean = 29.9), which could be further divided into two TRN groups: PD-G(small) (mean = 17.3) and PD-G(large) (mean = 44.3). Less variation was found in ALSD strains (mean = 21.7). The variation was even smaller after ALSD strains were subdivided into the A and G genotypes (mean = 13.3, for the G genotype; mean = 27.1, for the A genotype). Genetic variation at the PD0218 locus is potentially useful for sensitive discrimination of X. fastidiosa strains. However, TRN stability, variation range, and correlation to phenotypes should be evaluated in epidemiological applications such as pathotype identification and delineation of pathogen origin.
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26
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Gillen CM, Courtney HS, Schulze K, Rohde M, Wilson MR, Timmer AM, Guzman CA, Nizet V, Chhatwal G, Walker MJ. Opacity Factor Activity and Epithelial Cell Binding by the Serum Opacity Factor Protein of Streptococcus pyogenes Are Functionally Discrete. J Biol Chem 2008; 283:6359-66. [DOI: 10.1074/jbc.m706739200] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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27
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Bolduc GR, Madoff LC. The group B streptococcal alpha C protein binds alpha1beta1-integrin through a novel KTD motif that promotes internalization of GBS within human epithelial cells. MICROBIOLOGY-SGM 2008; 153:4039-4049. [PMID: 18048918 DOI: 10.1099/mic.0.2007/009134-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Group B Streptococcus (GBS) is the leading cause of bacterial pneumonia, sepsis and meningitis among neonates and a cause of morbidity among pregnant women and immunocompromised adults. GBS epithelial cell invasion is associated with expression of alpha C protein (ACP). Loss of ACP expression results in a decrease in GBS internalization and translocation across human cervical epithelial cells (ME180). Soluble ACP and its 170 amino acid N-terminal region (NtACP), but not the repeat protein RR', bind to ME180 cells and reduce internalization of wild-type GBS to levels obtained with an ACP-deficient isogenic mutant. In the current study, ACP colocalized with alpha(1)beta(1)-integrin, resulting in integrin clustering as determined by laser scanning confocal microscopy. NtACP contains two structural domains, D1 and D2. D1 is structurally similar to fibronectin's integrin-binding region (FnIII10). D1's (KT)D146 motif is structurally similar to the FnIII10 (RG)D1495 integrin-binding motif, suggesting that ACP binds alpha(1)beta(1)-integrin via the D1 domain. The (KT)D146A mutation within soluble NtACP reduced its ability to bind alpha(1)beta(1)-integrin and inhibit GBS internalization within ME180 cells. Thus ACP binding to human epithelial cell integrins appears to contribute to GBS internalization within epithelial cells.
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Affiliation(s)
- Gilles R Bolduc
- Department of Medicine, Brigham and Women's Hospital, 75 Fransis Street, Boston, MA 02115, USA.,Channing Laboratory, 181 Longwood Avenue, Boston, MA 02115, USA
| | - Lawrence C Madoff
- Department of Medicine, Brigham and Women's Hospital, 75 Fransis Street, Boston, MA 02115, USA.,Channing Laboratory, 181 Longwood Avenue, Boston, MA 02115, USA
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28
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Alpha C protein-specific immunity in humans with group B streptococcal colonization and invasive disease. Vaccine 2007; 26:502-8. [PMID: 18155812 DOI: 10.1016/j.vaccine.2007.11.034] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2007] [Revised: 11/05/2007] [Accepted: 11/15/2007] [Indexed: 02/04/2023]
Abstract
Alpha C protein, found in 76% of non-type III strains of group B Streptococcus (GBS), elicits antibodies protective against alpha C-expressing strains in experimental animals, making it an appealing carrier for a GBS conjugate vaccine. We determined whether natural exposure to alpha C elicits antibodies in women. Geometric mean concentrations of alpha C-specific IgM and IgG were similar by ELISA in sera from 58 alpha C GBS strain colonized and 174 age-matched non-colonized women (IgG 245 and 313 ng/ml; IgM 257 and 229 ng/ml, respectively), but acute sera from 13 women with invasive alpha C-expressing GBS infection had significantly higher concentrations (IgM 383 and IgG 476 ng/ml [p=0.036 and 0.038, respectively]). Convalescent sera from 5 of these women 16-49 days later had high alpha C-specific IgM and IgG concentrations (1355 and 4173 ng/ml, respectively). In vitro killing of alpha C-expressing GBS correlated with total alpha C-specific antibody concentration. Invasive disease but not colonization elicits alpha C-specific IgM and IgG in adults.
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29
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Stålhammar-Carlemalm M, Waldemarsson J, Johnsson E, Areschoug T, Lindahl G. Nonimmunodominant Regions Are Effective as Building Blocks in a Streptococcal Fusion Protein Vaccine. Cell Host Microbe 2007; 2:427-34. [DOI: 10.1016/j.chom.2007.10.003] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2007] [Revised: 08/27/2007] [Accepted: 10/12/2007] [Indexed: 11/28/2022]
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30
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Liu H, Rodes B, George R, Steiner B. Molecular characterization and analysis of a gene encoding the acidic repeat protein (Arp) of Treponema pallidum. J Med Microbiol 2007; 56:715-721. [PMID: 17510254 DOI: 10.1099/jmm.0.46943-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The acidic repeat protein (arp) genes from three subspecies of the treponeme Treponema pallidum (T. pallidum subsp. pallidum, Nichols strain; T. pallidum subsp. pertenue, CDC-1 and CDC-2 strains; and T. pallidum subsp. endemicum, Bosnia A strain) were cloned and sequenced. The predicted protein sequence contained a high percentage of glutamic acid, hence the name acidic repeat protein, or Arp. The protein had a potential membrane-spanning domain and a signal peptidase I site. The gene from the Nichols strain of T. pallidum subsp. pallidum contained a set of 14 nearly identical repeats of a 60 bp sequence, which occupied approximately 51 % of the length of the gene. Analyses of arp from laboratory strains showed that the 5' and 3' ends of the genes were conserved, but there was considerable heterogeneity in the number of repeats of this 60 bp sequence. Based on amino acid variations, the 14 sequence repeats could be classified into three types, which were named type I, type II and type III repeats. The type II repeat was the most common in the strains examined. The arp gene of the Nichols strain was subsequently cloned into the expression vector pBAD/TOPO ThioFusion. The expressed protein was detected in a Western blot assay using rabbit immune sera produced against T. pallidum, or synthetic peptides derived from the repeat sequences. Using an ELISA, rapid plasma reagin (RPR) test-positive sera reacted with synthetic peptides derived from the repeat region but not with peptides derived from N and C termini of the Arp protein. These results show that the Arp protein is immunogenic and could prove to be a useful target for serological diagnosis of T. pallidum infection.
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MESH Headings
- Amino Acid Sequence
- Animals
- Antibodies, Bacterial/immunology
- Bacterial Proteins/genetics
- Bacterial Proteins/immunology
- Base Sequence
- Binding Sites/genetics
- Blotting, Western
- Cloning, Molecular
- Conserved Sequence
- DNA, Bacterial/chemistry
- DNA, Bacterial/genetics
- Enzyme-Linked Immunosorbent Assay
- Humans
- Membrane Proteins/genetics
- Molecular Sequence Data
- Polymorphism, Genetic
- Protein Sorting Signals/genetics
- Protein Structure, Tertiary/genetics
- Rabbits
- Repetitive Sequences, Amino Acid/genetics
- Repetitive Sequences, Amino Acid/immunology
- Repetitive Sequences, Nucleic Acid
- Sequence Analysis, DNA
- Serum/immunology
- Syphilis Serodiagnosis/methods
- Treponema pallidum/genetics
- Treponema pallidum/immunology
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Affiliation(s)
- Hsi Liu
- National Center for HIV/AIDS, Viral Hepatitis, STD and TB Prevention, Centers for Disease Control and Prevention, Atlanta, GA 30333, USA
| | - Berta Rodes
- Hospital Carlos III, Madrid, Spain
- National Center for HIV/AIDS, Viral Hepatitis, STD and TB Prevention, Centers for Disease Control and Prevention, Atlanta, GA 30333, USA
| | - Robert George
- National Center for HIV/AIDS, Viral Hepatitis, STD and TB Prevention, Centers for Disease Control and Prevention, Atlanta, GA 30333, USA
| | - Bret Steiner
- National Center for HIV/AIDS, Viral Hepatitis, STD and TB Prevention, Centers for Disease Control and Prevention, Atlanta, GA 30333, USA
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31
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Ho YR, Li CM, Su HP, Wu JH, Tseng YC, Lin YJ, Wu JJ. Variation in the number of tandem repeats and profile of surface protein genes among invasive group B Streptococci correlates with patient age. J Clin Microbiol 2007; 45:1634-6. [PMID: 17344358 PMCID: PMC1865878 DOI: 10.1128/jcm.00122-07] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The average number of tandem repeats of the rib gene (which encodes the Rib surface protein) in invasive group B streptococci from 29 neonates was smaller than that from 20 adults (6.8 and 8.6, respectively; P<0.05), implying a distinct contribution of immunity toward this age-related variation.
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Affiliation(s)
- Yueh-Ren Ho
- Department of Biochemistry and Molecular Biology, College of Medicine, National Cheng Kung University, No. 1 University Road, Tainan 701, Taiwan
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32
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Baron MJ, Filman DJ, Prophete GA, Hogle JM, Madoff LC. Identification of a glycosaminoglycan binding region of the alpha C protein that mediates entry of group B Streptococci into host cells. J Biol Chem 2007; 282:10526-36. [PMID: 17259175 DOI: 10.1074/jbc.m608279200] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Group B Streptococcus (GBS) frequently colonizes the human gastrointestinal and gynecological tracts and less frequently causes deep tissue infections. The transition between colonization and infection depends upon the ability of the organism to cross epithelial barriers. The alpha C protein (ACP) on the surface of GBS contributes to this process. A virulence factor in mouse models of infection, and prototype for a family of Gram-positive bacterial surface proteins, ACP facilitates GBS entry into human cervical epithelial cells and movement across cell layers. ACP binds to host cell surface glycosaminoglycan (GAG). From crystallography, we have identified a cluster of basic residues (BR2) that is a putative GAG binding area in Domain 2, near the junction of the N-terminal domain of ACP and the first of a series of tandem amino acid repeats. D2-R, a protein construct including this region, binds to cells similarly to full-length ACP. We now demonstrate that the predicted charged BR2 residues confer GAG binding; site-directed mutagenesis of these residues (Arg(172), Arg(185), or Lys(196)) eliminates cell-binding activity of construct D2-R. In addition, we have constructed a GBS strain expressing a variant ACP with a charge-neutralizing substitution at residue 185. This strain enters host cells less effectively than does the wild-type strain and similarly to an ACP null mutant strain. The point mutant strain transcytoses similarly to the wild-type strain. These data indicate that GAG-binding activity underlies ACP-mediated cellular entry of GBS. GBS entry into host cells and transcytosis of host cells may occur by distinct mechanisms.
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MESH Headings
- Amino Acid Sequence
- Amino Acid Substitution
- Animals
- Antigens, Surface/chemistry
- Antigens, Surface/genetics
- Antigens, Surface/metabolism
- Bacterial Adhesion/genetics
- Bacterial Proteins/chemistry
- Bacterial Proteins/genetics
- Bacterial Proteins/metabolism
- Bacterial Translocation/genetics
- Binding Sites/genetics
- Cell Line, Tumor
- Cervix Uteri/metabolism
- Cervix Uteri/microbiology
- Crystallography, X-Ray
- Epithelial Cells/metabolism
- Epithelial Cells/microbiology
- Female
- Gastrointestinal Diseases/genetics
- Gastrointestinal Diseases/metabolism
- Gastrointestinal Diseases/microbiology
- Genital Diseases, Female/genetics
- Genital Diseases, Female/metabolism
- Genital Diseases, Female/microbiology
- Glycosaminoglycans/chemistry
- Glycosaminoglycans/metabolism
- Humans
- Mice
- Molecular Sequence Data
- Mutagenesis, Site-Directed
- Point Mutation
- Protein Binding/genetics
- Protein Structure, Tertiary/genetics
- Streptococcal Infections/genetics
- Streptococcal Infections/metabolism
- Streptococcus agalactiae/chemistry
- Streptococcus agalactiae/genetics
- Streptococcus agalactiae/metabolism
- Streptococcus agalactiae/pathogenicity
- Virulence Factors/chemistry
- Virulence Factors/genetics
- Virulence Factors/metabolism
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Affiliation(s)
- Miriam J Baron
- Channing Laboratory, Department of Medicine, Brigham & Women's Hospital, Boston, Massachusetts 02115, USA.
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33
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Seifert KN, Adderson EE, Whiting AA, Bohnsack JF, Crowley PJ, Brady LJ. A unique serine-rich repeat protein (Srr-2) and novel surface antigen (epsilon) associated with a virulent lineage of serotype III Streptococcus agalactiae. MICROBIOLOGY-SGM 2006; 152:1029-1040. [PMID: 16549667 DOI: 10.1099/mic.0.28516-0] [Citation(s) in RCA: 94] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Group B streptococci (GBS) are pathogens of both neonates and adults, with serotype III strains in particular being associated with invasive disease and meningitis. In this study, a novel GBS surface antigen, epsilon, was found to be co-expressed with the previously reported delta antigen on an identical subset of serotype III GBS. Expression of delta/epsilon on the surface of serotype III GBS was shown to distinguish the restriction digest pattern (RDP) III-3 and multilocus sequence typing (ST)-17 lineage. epsilon-Specific antibodies were reactive with a unique, high-molecular-mass, serine-rich repeat protein (Srr-2) found exclusively in RDP III-3 strains. The gene encoding Srr-2 was located within a putative accessory secretory locus that included secY2 and secA2 homologues and had a genetic organization similar to that of the secY2/A2 locus of staphylococci. In contrast, serotype III delta/epsilon-negative strains and strains representative of serotypes Ia, Ib, Ic and II shared a common Srr-encoding gene, srr-1, and an organization of the secY2/A2 locus similar to that of previously reported serotype Ic, delta/epsilon-negative serotype III and serotype V GBS strains. Representative serotype III delta/epsilon-positive strains had LD(90) values 3-4 logs less than those of serotype III delta/epsilon-negative strains in a neonatal mouse model of infection. These results indicate that the RDP III-3/ST-17 lineage expresses Srr-2 and is highly virulent in an in vivo model of neonatal sepsis.
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Affiliation(s)
- Kyle N Seifert
- Department of Biology, James Madison University, Harrisonburg, VA 22807, USA
| | - Elisabeth E Adderson
- Department of Infectious Diseases, St Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - April A Whiting
- Department of Pediatrics, University of Utah Health Sciences Center, Salt Lake City, UT 84132, USA
| | - John F Bohnsack
- Department of Pediatrics, University of Utah Health Sciences Center, Salt Lake City, UT 84132, USA
| | - Paula J Crowley
- Department of Oral Biology, College of Dentistry, University of Florida, Gainesville, FL 32610, USA
| | - L Jeannine Brady
- Department of Oral Biology, College of Dentistry, University of Florida, Gainesville, FL 32610, USA
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34
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Blanc G, Ngwamidiba M, Ogata H, Fournier PE, Claverie JM, Raoult D. Molecular evolution of rickettsia surface antigens: evidence of positive selection. Mol Biol Evol 2005; 22:2073-83. [PMID: 15972845 DOI: 10.1093/molbev/msi199] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The Rickettsia genus is a group of obligate intracellular parasitic alpha-proteobacteria that includes human pathogens responsible for the typhus disease and various types of spotted fevers. rOmpA and rOmpB are two members of the "surface cell antigen" (Sca) autotransporter (AT) protein family that may play key roles in the adhesion of the Rickettsia cells to the host tissue. These molecules are likely determinants for the pathogenicity of the Rickettsia and represent good candidates for vaccine development. We identified the 17 members of this family of outer-membrane proteins in nine fully sequenced Rickettsia genomes. The typical architecture of the Sca proteins is composed of an N-terminal signal peptide and a C-terminal AT domain that promote the export of the central passenger domain to the outside of the bacteria. A characteristic of this family is the frequent degradation of the genes, which results in different subsets of the sca genes being expressed among Rickettsia species. Here, we present a detailed analysis of their phylogenetic relationships and evolution. We provide strong evidence that rOmpA and rOmpB as well as three other members of the Sca protein family--Sca1, Sca2, and Sca4--have evolved under positive selection. The exclusive distribution of the predicted positively selected sites within the passenger domains of these proteins argues that these regions are involved in the interaction with the host and may be locked in "arms race" coevolutionary conflicts.
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Affiliation(s)
- Guillaume Blanc
- Information Génomique et Structurale, UPR 2589, 31 Chemin Joseph Aiguier, 13402 Marseille Cedex 20, France.
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35
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Seepersaud R, Hanniffy SB, Mayne P, Sizer P, Le Page R, Wells JM. Characterization of a novel leucine-rich repeat protein antigen from group B streptococci that elicits protective immunity. Infect Immun 2005; 73:1671-83. [PMID: 15731068 PMCID: PMC1064916 DOI: 10.1128/iai.73.3.1671-1683.2005] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Group B streptococci (GBS) usually behave as commensal organisms that asymptomatically colonize the gastrointestinal and urogenital tracts of adults. However, GBS are also pathogens and the leading bacterial cause of life-threatening invasive disease in neonates. While the events leading to transmission and disease in neonates remain unclear, GBS carriage and level of colonization in the mother have been shown to be significant risk factors associated with invasive infection. Surface antigens represent ideal vaccine targets for eliciting antibodies that can act as opsonins and/or inhibit colonization and invasion. Using a genetic screen for exported proteins in GBS, we identified a gene, designated lrrG, that encodes a novel LPXTG anchored surface antigen containing leucine-rich repeat (LRR) motifs found in bacterial invasins and other members of the LRR protein family. Southern blotting showed that lrrG was present in all GBS strains tested, representing the nine serotypes, and revealed the presence of an lrrG homologue in Streptococcus pyogenes. Recombinant LrrG protein was shown in vitro to adhere to epithelial cells in a dose-dependent manner, suggesting that it may function as an adhesion factor in GBS. More importantly, immunization with recombinant LrrG elicited a strong immunoglobulin G response in CBA/ca mice and protected against lethal challenge with virulent GBS. The data presented in this report suggest that this conserved protein is a highly promising candidate antigen for use in a GBS vaccine.
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Affiliation(s)
- Ravin Seepersaud
- Cortecs Centre for Vaccine Discovery, Department of Pathology, University of Cambridge, Cambridge, UK
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36
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Aupérin TC, Bolduc GR, Baron MJ, Heroux A, Filman DJ, Madoff LC, Hogle JM. Crystal structure of the N-terminal domain of the group B streptococcus alpha C protein. J Biol Chem 2005; 280:18245-52. [PMID: 15753100 DOI: 10.1074/jbc.m412391200] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Group B Streptococcus (GBS) is the leading cause of bacterial pneumonia, sepsis, and meningitis among neonates and an important cause of morbidity among pregnant women and immunocompromised adults. Invasive diseases due to GBS are attributed to the ability of the pathogen to translocate across human epithelial surfaces. The alpha C protein (ACP) has been identified as an invasin that plays a role in internalization and translocation of GBS across epithelial cells. The soluble N-terminal domain of ACP (NtACP) blocks the internalization of GBS. We determined the 1.86-A resolution crystal structure of NtACP comprising residues Ser(52) through Leu(225) of the full-length ACP. NtACP has two domains, an N-terminal beta-sandwich and a C-terminal three-helix bundle. Structural and topological alignments reveal that the beta-sandwich shares structural elements with the type III fibronectin fold (FnIII), but includes structural elaborations that make it unique. We have identified a potential integrin-binding motif consisting of Lys-Thr-Asp(146), Arg(110), and Asp(118). A similar arrangement of charged residues has been described in other invasins. ACP shows a heparin binding activity that requires NtACP. We propose a possible heparin-binding site, including one surface of the three-helix bundle, and nearby portions of the sandwich and repeat domains. We have validated this prediction using assays of the heparin binding and cell-adhesion properties of engineered fragments of ACP. This is the first crystal structure of a member of the highly conserved Gram-positive surface alpha-like protein family, and it will enable the internalization mechanism of GBS to be dissected at the atomic level.
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Affiliation(s)
- Thierry C Aupérin
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115, USA
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37
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Bröker G, Spellerberg B. Surface proteins of Streptococcus agalactiae and horizontal gene transfer. Int J Med Microbiol 2004; 294:169-75. [PMID: 15493827 DOI: 10.1016/j.ijmm.2004.06.018] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
Abstract
Streptococcus agalactiae is responsible for serious infectious diseases in neonates, immuno-compromised adult patients and causes bovine mastitis in animal hosts. Genome sequencing projects revealed strong indications for horizontal gene transfer events leading to virulence acquisition and genetic diversity in this species. Bacterial surface proteins establish the first contact with host tissues and represent interesting targets for the exchange of virulence properties among different streptococci. This review will focus on horizontal gene transfer events in characterized S. agalactiae surface proteins, mobile genetic elements adjacent to the corresponding genes and will discuss potential mechanisms of transfer.
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Affiliation(s)
- Gerd Bröker
- Department of Medical Microbiology and Hygiene, University of Ulm, Robert Koch Str 8, D-89081 Ulm, Germany
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38
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Hijnen M, Mooi FR, van Gageldonk PGM, Hoogerhout P, King AJ, Berbers GAM. Epitope structure of the Bordetella pertussis protein P.69 pertactin, a major vaccine component and protective antigen. Infect Immun 2004; 72:3716-23. [PMID: 15213111 PMCID: PMC427433 DOI: 10.1128/iai.72.7.3716-3723.2004] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Bordetella pertussis is reemerging in several countries with a traditionally high vaccine uptake. An analysis of clinical isolates revealed antigenic divergence between vaccine strains and circulating strains with respect to P.69 pertactin. Polymorphisms in P.69 pertactin are mainly limited to regions comprised of amino acid repeats, designated region 1 and region 2. Region 1 flanks the RGD motif, which is involved in adherence. Although antibodies against P.69 pertactin are implicated in protective immunity, little is known about the structure and location of its epitopes. Here we describe the identification by pepscan analysis of the locations of mainly linear epitopes recognized by human sera and mouse monoclonal antibodies (MAbs). A total of 24 epitopes were identified, and of these only 2 were recognized by both MAbs and human antibodies in serum. A number of immunodominant epitopes were identified which were recognized by 78 to 93% of the human sera tested. Blocking experiments indicated the presence of high-avidity human antibodies against conformational epitopes. Human antibodies against linear epitopes had much lower avidities, as they were unable to block MAbs. Pepscan analyses revealed several MAbs which bound to both region 1 and region 2. The two regions are separated by 289 amino acids in the primary structure, and we discuss the possibility that they form a single conformational epitope. Thus, both repeat regions may serve to deflect the immune response targeted to the functional domain of P.69 pertactin. This may explain why the variation in P.69 pertactin is so effective, despite the fact that it is limited to only two small segments of the molecule.
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Affiliation(s)
- Marcel Hijnen
- Laboratory for Vaccine Preventable Diseases, National Institute of Public Health, Antonie van Leeuwenhoek Laan 1, P.O. Box 1, Bilthoven, The Netherlands
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39
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Baron MJ, Bolduc GR, Goldberg MB, Aupérin TC, Madoff LC. Alpha C protein of group B Streptococcus binds host cell surface glycosaminoglycan and enters cells by an actin-dependent mechanism. J Biol Chem 2004; 279:24714-23. [PMID: 15044471 DOI: 10.1074/jbc.m402164200] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Group B Streptococcus (GBS) colonizes mucosal surfaces of the human gastrointestinal and gynecological tracts and causes disease in a wide range of patients. Invasive illness occurs after organisms traverse an epithelial boundary and enter deeper tissues. Previously we have reported that the alpha C protein (ACP) on the surface of GBS mediates GBS entry into ME180 cervical epithelial cells and GBS translocation across layers of these cells. We now demonstrate that ACP interacts with host cell glycosaminoglycan (GAG); the interaction of ACP with ME180 cells is inhibited if cells are pretreated with sodium chlorate, an inhibitor of sulfate incorporation, or with heparitinases. The interaction is also inhibited in the presence of soluble heparin or heparan sulfate or host cell-derived GAG. In addition, ACP binds soluble heparin specifically in inhibition and dot blot assays. After interaction with host GAG, soluble ACP enters ME180 cells and fractionates to the eukaryotic cell cytosol. These events are inhibited in cells pretreated with cytochalasin D or with Clostridium difficile toxin B. These data indicate that full-length ACP interacts with ME180 cell GAG and enters the eukaryotic cell cytosol by a mechanism that involves Rho GTPase-dependent actin rearrangements. We suggest that these molecular interactions drive ACP-mediated translocation of GBS across epithelial barriers, thereby facilitating invasive GBS infection.
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Affiliation(s)
- Miriam J Baron
- Channing Laboratory and Division of Infectious Diseases, Brigham and Women's Hospital, Boston, Massachusetts 02115, USA.
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40
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Zhang XF, Zhang JZ, Long SW, Ruble RP, Yu XJ. Experimental Ehrlichia chaffeensis infection in beagles. J Med Microbiol 2004; 52:1021-1026. [PMID: 14532348 DOI: 10.1099/jmm.0.05234-0] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
A canine model for human monocytic ehrlichiosis was used to assess persistent infection and antigenic variation of Ehrlichia chaffeensis. Two beagle dogs were infected subcutaneously with E. chaffeensis Arkansas strain. The dogs were observed for 6 months after inoculation for clinical signs, blood chemistry changes, antibodies to E. chaffeensis and presence of E. chaffeensis in the blood. Both dogs developed thrombocytopenia, but exhibited normal body temperatures during the entire course of infection. In one dog, E. chaffeensis was cultivated for up to 74 days post-inoculation and E. chaffeensis DNA was detected in the dog's blood for up to 81 days. In the other dog, E. chaffeensis was cultured for up to 102 days and E. chaffeensis DNA was detected in the blood for up to 117 days. PCR amplification and DNA sequence analysis indicated that there was no genetic variation in the 120 kDa outer-membrane glycoprotein gene of E. chaffeensis during infection of the dogs. The dogs developed antibodies to the immunodominant proteins of E. chaffeensis, including the 175, 140, 120, 80, 50 and 28 kDa proteins, starting in the fifth week post-inoculation. The dogs maintained high antibody titres throughout the 6-month study period. These results indicate that dogs become carriers of E. chaffeensis for 2-4 months after infection without exhibiting signs of clinical disease, suggesting that dogs may serve as a natural host for E. chaffeensis.
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Affiliation(s)
- Xiao-Feng Zhang
- Departments of Pathology and Microbiology and Immunology, Center for Biodefense and Emerging Infectious Diseases1 and Animal Resource Center2, University of Texas Medical Branch, Galveston, Texas 77555-0609, USA
| | - Jian-Zhi Zhang
- Departments of Pathology and Microbiology and Immunology, Center for Biodefense and Emerging Infectious Diseases1 and Animal Resource Center2, University of Texas Medical Branch, Galveston, Texas 77555-0609, USA
| | - S Wesley Long
- Departments of Pathology and Microbiology and Immunology, Center for Biodefense and Emerging Infectious Diseases1 and Animal Resource Center2, University of Texas Medical Branch, Galveston, Texas 77555-0609, USA
| | - Randall P Ruble
- Departments of Pathology and Microbiology and Immunology, Center for Biodefense and Emerging Infectious Diseases1 and Animal Resource Center2, University of Texas Medical Branch, Galveston, Texas 77555-0609, USA
| | - Xue-Jie Yu
- Departments of Pathology and Microbiology and Immunology, Center for Biodefense and Emerging Infectious Diseases1 and Animal Resource Center2, University of Texas Medical Branch, Galveston, Texas 77555-0609, USA
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41
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Puopolo KM, Madoff LC. Upstream short sequence repeats regulate expression of the alpha C protein of group B Streptococcus. Mol Microbiol 2004; 50:977-91. [PMID: 14617155 DOI: 10.1046/j.1365-2958.2003.03745.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Group B streptococci (GBS) express a family of repeat-containing surface proteins, the prototype of which is the alpha C protein expressed in type Ia/C strain A909. We have isolated a series of mutant GBS strains by mouse-passage of A909 that do not produce normal levels of the alpha C protein. Polymerase chain reaction amplification and sequencing of the gene encoding the alpha C protein, bca, from four mutant strains revealed the presence of a full-length gene in each strain. However, Northern and RT-PCR analysis revealed greatly reduced levels of RNA encoding the alpha C protein. Sequence analysis of the mutant genes found the coding region unchanged from the wild-type gene in each case, but variation was observed in a specific locus located 110 bp upstream of the start codon. The presence of a 5-nucleotide repeat, AGATT, and a string of adenine residues mark this locus. Both deletion and expansion of the AGATT motif were associated with the complete null phenotype. Deletions in the string of adenine residues were associated with both a decreased-production phenotype and a complete null phenotype. Cloning of this upstream region into a green-fluorescent protein (GFP) reporter system in GBS demonstrated promoter activity that was completely abolished by changes in the pentanucleotide repeat or adenine string. Primer extension studies of the wild-type strain revealed one dominant and two minor transcription start sites. Primer extension studies of the null and low-expression mutant strains revealed that the dominant transcript is completely absent in each mutant. The short sequence repeat locus is located at position - 55 to - 78 relative to the start site of the dominant transcript. We have demonstrated in vitro phase variation in expression of the alpha C protein associated with variation at the pentanucleotide repeat locus. We conclude that this short sequence repeat motif is located upstream of the dominant promoter for the alpha C protein and represents a regulatory site for alpha C protein expression. This is the first evidence of transcriptional regulation by short-sequence repeats in a Gram-positive organism.
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Affiliation(s)
- Karen M Puopolo
- Department of Newborn Medicine, Brigham and Womens' Hospital, Harvard Medical School, Boston, MA, USA.
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42
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Bolduc GR, Baron MJ, Gravekamp C, Lachenauer CS, Madoff LC. The alpha C protein mediates internalization of group B Streptococcus within human cervical epithelial cells. Cell Microbiol 2002; 4:751-8. [PMID: 12427097 DOI: 10.1046/j.1462-5822.2002.00227.x] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Group B Streptococcus (GBS) is the leading cause of bacterial chorioamnionitis and neonatal pneumonia, sepsis, and meningitis. Deletion of the alpha C protein gene (bca) attenuates the virulence of GBS in an animal model; significant survival differences in the first 24 h of infection suggest a pathogenic role for the alpha C protein early in the infection process. We examined the role of alpha C protein in the association between GBS and mucosal surfaces using a human cervical epithelial cell line, ME180. Fluorescent and confocal microscopy and flow cytometry demonstrated that 9-repeat alpha C protein binds to the surface of ME180 cells. Isolated N-terminal region of this protein also binds to these cells and competitively inhibits binding of the full protein. Wild-type GBS strain A909 and the bca-null isogenic mutant JL2053 bound similarly to the surface of ME180 cells. However, A909 entered these cells threefold more. Internalization of A909 was inhibited with 2- and 9-repeat alpha C and with N-terminal region alone but not by repeat region-specific peptide. Translocation across polarized ME180 membranes was fivefold greater for A909 than for JL2053. These findings suggest a role for the alpha C protein in interaction with epithelial surfaces and initiation of infection.
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Affiliation(s)
- G R Bolduc
- Channing Laboratory, Boston, MA 02115, USA.
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43
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Glaser P, Rusniok C, Buchrieser C, Chevalier F, Frangeul L, Msadek T, Zouine M, Couvé E, Lalioui L, Poyart C, Trieu-Cuot P, Kunst F. Genome sequence of Streptococcus agalactiae, a pathogen causing invasive neonatal disease. Mol Microbiol 2002; 45:1499-513. [PMID: 12354221 DOI: 10.1046/j.1365-2958.2002.03126.x] [Citation(s) in RCA: 350] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Streptococcus agalactiae is a commensal bacterium colonizing the intestinal tract of a significant proportion of the human population. However, it is also a pathogen which is the leading cause of invasive infections in neonates and causes septicaemia, meningitis and pneumonia. We sequenced the genome of the serogroup III strain NEM316, responsible for a fatal case of septicaemia. The genome is 2 211 485 base pairs long and contains 2118 protein coding genes. Fifty-five per cent of the predicted genes have an ortholog in the Streptococcus pyogenes genome, representing a conserved backbone between these two streptococci. Among the genes in S. agalactiae that lack an ortholog in S. pyogenes, 50% are clustered within 14 islands. These islands contain known and putative virulence genes, mostly encoding surface proteins as well as a number of genes related to mobile elements. Some of these islands could therefore be considered as pathogenicity islands. Compared with other pathogenic streptococci, S. agalactiae shows the unique feature that pathogenicity islands may have an important role in virulence acquisition and in genetic diversity.
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Affiliation(s)
- Philippe Glaser
- Laboratoire de Génomique des Microorganismes Pathogènes, Institute Pasteur, Paris, France
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44
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Alvarez P, Leguizamón MS, Buscaglia CA, Pitcovsky TA, Campetella O. Multiple overlapping epitopes in the repetitive unit of the shed acute-phase antigen from Trypanosoma cruzi enhance its immunogenic properties. Infect Immun 2001; 69:7946-9. [PMID: 11705983 PMCID: PMC98897 DOI: 10.1128/iai.69.12.7946-7949.2001] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The repetitive shed acute-phase antigen (SAPA) from Trypanosoma cruzi was thoroughly mapped by SPOT peptides and phage display strategies, showing that a single SAPA repeat is composed of multiple overlapping B-cell epitopes. We propose that this intricate antigenic structure constitutes an alternative device to repetitiveness in order to improve its immunogenicity.
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Affiliation(s)
- P Alvarez
- Instituto de Investigaciones Biotecnológicas, Universidad Nacional de General San Martin, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina
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45
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Abstract
Streptococcus agalactiae is an important human pathogen causing severe neonatal infections. During the course of infection, S. agalactiae colonizes and invades a number of different host compartments. Bacterial molecules including the polysaccharide capsule, the hemolysin, the C5a peptidase, the C-proteins, the hyaluronate lyase and a number of unknown bacterial components determine the interaction with host tissues. This review summarizes our current knowledge about these interactions.
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Affiliation(s)
- B Spellerberg
- Institute of Medical Microbiology and National Reference Center for Streptococci, University Hospital Aachen, Pauwelsstr. 30, D-52057, Aachen, Germany.
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46
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Maeland JA, Bevanger L, Iversen G, Lyng RV. bca, beta gene, and gene product divergency in reference and prototype strains of streptococcus agalactiae. CLINICAL AND DIAGNOSTIC LABORATORY IMMUNOLOGY 1999; 6:986-8. [PMID: 10548599 PMCID: PMC95811 DOI: 10.1128/cdli.6.6.986-988.1999] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Reference and prototype strains of Streptococcus agalactiae (GBS) were originally selected on the basis of phenotypic traits which, however, do not always mirror genotypic traits. A total of 14 reference and prototype GBS strains were examined by PCR designed to detect the bca and beta genes, encoding the c proteins c(alpha) and c(beta), respectively. The cognate proteins were detected by whole-cell-based fluorescent antibody testing and Western blotting. The PCR for beta gene detection and the antibody-based c(beta) protein detection showed concordant results with all of the isolates, whereas 7 of 14 strains which did not express c(alpha) protein at detectable levels contained bca gene elements, consistent with bca gene and gene product divergency in these strains. The results emphasize the importance of genetic characterization of reference and prototype strains of GBS which, in the past, have been selected on the basis of phenotypic traits.
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Affiliation(s)
- J A Maeland
- Department of Microbiology, School of Medicine, Norwegian University of Science and Technology, N-7006, Trondheim, Norway
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47
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Kvam AI, Bevanger L, Maeland JA. Properties and distribution of the putative R3 protein of Streptococcus agalactiae. APMIS 1999; 107:869-74. [PMID: 10519324 DOI: 10.1111/j.1699-0463.1999.tb01485.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Strain-variable Streptococcus agalactiae (group B streptococci; GBS) proteins exposed at the bacterial cell surface are important markers in GBS serotyping. These proteins include the c proteins c(alpha) and c(beta) and the R proteins R1 through R4, of which R1 and R4 have been studied most extensively. This study presents the characteristics of a protein which was expressed by a capsular antigen type V GBS strain shown by means of polyclonal and monoclonal antibody testing. Examination of a number of reference and prototype strains by fluorescent antibody testing and Western blotting provided evidence that the serotype V-derived protein was the R3 protein of GBS, previously defined on the basis of immunoprecipitation assays. The putative R3 protein formed ladder-like banding patterns on Western blotting with polypeptides in the 30 kDa to > or = 140 kDa range, was destroyed by pepsin digestion, and partially degraded by trypsin digestion. The protein was expressed by 10 (6.5%) of 153 clinical GBS strains tested, the expression being restricted to isolates of the capsular antigen types II, III, and V. Some isolates expressed both the c(beta) and the R3 protein. Expression in combination with c(alpha) or R4 protein synthesis was not detected. Inclusion of the anti-R3 monoclonal antibody among antibody reagents for GBS serotyping will enhance the discriminatory power of this typing method.
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Affiliation(s)
- A I Kvam
- Sør-Trøndelag College, Department of Medical Laboratory Technology, Trondheim, Norway
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48
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Musatovova O, Alderete JF. The Trichomonas vaginalis phenotypically varying P270 immunogen is highly conserved except for numbers of repeated elements. Microb Pathog 1999; 27:93-104. [PMID: 10458920 DOI: 10.1006/mpat.1999.0281] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The prominent and phenotypically variable immunogenic protein of Trichomonas vaginalis, termed P270, is present in all isolates. Most, if not all, patients make antibody to the DREGRD epitope contained in the 333 bp tandemly repeating element (TRE). The complete sequence of p270 of a fresh clinical isolate was recently derived (Musatovova and Alderete, Microb Pathogen 1998; 24: 223-39). We hypothesized that the size polymorphisms of P270 were due to the varied number of TREs that comprise a large, central portion of the gene. In this study, we analysed the p270 coding regions of ten representative isolates. It was determined also that the sequence of the TRE of different p270 genes shared > or =99% identity, and individual TREs of the same p270 gene showed them to have identical nucleotide sequences, affirming the highly-conserved nature of this element within each gene. The coding regions upstream and downstream of the central TREs were then generated by PCR amplification using specific primers. The PCR products corresponding to the 5' and 3'-end coding, non-repeat sequences were then subjected to restriction analyses, and the regions were highly conserved for all p270 genes. The complete sequence of two p270 genes showed > or = 99% identity of amino acids at the N- and C-terminal regions of p270, further reinforcing that the reported polymorphisms in Mr of P270 is due to the varying number of TREs and, therefore, the size of the TRE domain. In support of this hypothesis and during these analyses, one isolate, T. vaginalis T016, was discovered which possessed a p270 gene with only one partial repeat unit. Importantly, and as with all other p270 genes, transcription of this single-repeat p270 gene in isolate T016 was confirmed. The start codon for the p270 T016 gene was preceded by the 12 nucleotide consensus Inr promoter-like sequence (TCATTTTTAATA) and possessed a putative transmembrane domain at the carboxy terminus.
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MESH Headings
- Amino Acid Sequence
- Animals
- Antigens, Protozoan/biosynthesis
- Antigens, Protozoan/chemistry
- Antigens, Protozoan/genetics
- Antigens, Protozoan/immunology
- Blotting, Southern
- DNA, Protozoan/analysis
- DNA, Protozoan/genetics
- Genes, Protozoan
- Humans
- Molecular Sequence Data
- Polymerase Chain Reaction/methods
- Polymorphism, Genetic
- Protozoan Proteins/biosynthesis
- Protozoan Proteins/chemistry
- Protozoan Proteins/genetics
- Protozoan Proteins/immunology
- Restriction Mapping
- Sequence Analysis, DNA
- Tandem Repeat Sequences/genetics
- Trichomonas Infections/parasitology
- Trichomonas vaginalis/genetics
- Trichomonas vaginalis/immunology
- Trichomonas vaginalis/metabolism
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Affiliation(s)
- O Musatovova
- Department of Microbiology, The University of Texas Health Science Center at San Antonio, 78284-7758, USA
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49
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Yu XJ, Crocquet-Valdes PA, Cullman LC, Popov VL, Walker DH. Comparison of Ehrlichia chaffeensis recombinant proteins for serologic diagnosis of human monocytotropic ehrlichiosis. J Clin Microbiol 1999; 37:2568-75. [PMID: 10405403 PMCID: PMC85285 DOI: 10.1128/jcm.37.8.2568-2575.1999] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Diagnosis of human monocytotropic ehrlichiosis (HME) generally depends on serology that detects the antibody response to immunodominant proteins of Ehrlichia chaffeensis. Protein immunoblotting was used to evaluate the reaction of the antibodies in patients' sera with the recombinant E. chaffeensis 120- and 28-kDa proteins as well as the 106- and the 37-kDa proteins. The cloning of the genes encoding the latter two proteins is described in this report. Immunoelectron microscopy demonstrated that the 106-kDa protein is located at the surfaces of ehrlichiae and on the intramorular fibrillar structures associated with E. chaffeensis. The 37-kDa protein is homologous to the iron-binding protein of gram-negative bacteria. Forty-two serum samples from patients who were suspected to have HME were tested by immunofluorescence (IFA) using E. chaffeensis antigen and by protein immunoblotting using recombinant E. chaffeensis proteins expressed in Escherichia coli. Thirty-two serum samples contained IFA antibodies at a titer of 1:64 or greater. The correlation of IFA and recombinant protein immunoblotting was 100% for the 120-kDa protein, 41% for the 28-kDa protein, 9.4% for the 106-kDa protein, and 0% for the 37-kDa protein. None of the recombinant antigens yielded false-positive results. All the sera reactive with the recombinant 28- or the 106-kDa proteins also reacted with the recombinant 120-kDa protein.
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Affiliation(s)
- X J Yu
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas 77555-0609, USA
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Gravekamp C, Kasper DL, Paoletti LC, Madoff LC. Alpha C protein as a carrier for type III capsular polysaccharide and as a protective protein in group B streptococcal vaccines. Infect Immun 1999; 67:2491-6. [PMID: 10225912 PMCID: PMC115995 DOI: 10.1128/iai.67.5.2491-2496.1999] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/1998] [Accepted: 02/18/1999] [Indexed: 11/20/2022] Open
Abstract
The alpha C protein, a protective surface protein of group B streptococci (GBS), is present in most non-type III GBS strains. Conjugate vaccines composed of the alpha C protein and type III capsular polysaccharide (CPS) might be protective against most GBS infections. In this study, the type III CPS was covalently coupled to full-length, nine-repeat alpha C protein (resulting in III-alpha9r conjugate vaccine) or to two-repeat alpha C protein (resulting in III-alpha2r conjugate vaccine) by reductive amination. Initial experiments with the III-alpha9r vaccine showed that it was poorly immunogenic in mice with respect to both vaccine antigens and was suboptimally efficacious in providing protection in mice against challenge with GBS. Therefore, modified vaccination protocols were used with the III-alpha2r vaccine. Female mice were immunized three times with 0.5, 5, or 20 microgram of the III-alpha2r vaccine with an aluminum hydroxide adjuvant and bred. Ninety-five percent of neonatal mice born to dams immunized with the III-alpha2r vaccine survived challenge with GBS expressing type III CPS, and 60% survived challenge with GBS expressing wild-type (nine-repeat) alpha C protein; 18 and 17%, respectively, of mice in the negative control groups survived (P, <0.0001). These protection levels did not differ significantly from those obtained with the type III CPS-tetanus toxoid conjugate vaccine and the unconjugated two-repeat alpha C protein, which protected 98 and 58% of neonates from infection with GBS expressing type III CPS or the alpha C protein, respectively. Thus, the two-repeat alpha C protein in the vaccine was immunogenic and simultaneously enhanced the immunogenicity of type III CPS. III-alpha vaccines may be alternatives to GBS polysaccharide-tetanus toxoid vaccines, eliciting additional antibodies protective against GBS infection.
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Affiliation(s)
- C Gravekamp
- Channing Laboratory, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA
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