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George A, Patil AG, Mahalakshmi R. ATP-independent assembly machinery of bacterial outer membranes: BAM complex structure and function set the stage for next-generation therapeutics. Protein Sci 2024; 33:e4896. [PMID: 38284489 PMCID: PMC10804688 DOI: 10.1002/pro.4896] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2023] [Revised: 12/28/2023] [Accepted: 12/31/2023] [Indexed: 01/30/2024]
Abstract
Diderm bacteria employ β-barrel outer membrane proteins (OMPs) as their first line of communication with their environment. These OMPs are assembled efficiently in the asymmetric outer membrane by the β-Barrel Assembly Machinery (BAM). The multi-subunit BAM complex comprises the transmembrane OMP BamA as its functional subunit, with associated lipoproteins (e.g., BamB/C/D/E/F, RmpM) varying across phyla and performing different regulatory roles. The ability of BAM complex to recognize and fold OM β-barrels of diverse sizes, and reproducibly execute their membrane insertion, is independent of electrochemical energy. Recent atomic structures, which captured BAM-substrate complexes, show the assembly function of BamA can be tailored, with different substrate types exhibiting different folding mechanisms. Here, we highlight common and unique features of its interactome. We discuss how this conserved protein complex has evolved the ability to effectively achieve the directed assembly of diverse OMPs of wide-ranging sizes (8-36 β-stranded monomers). Additionally, we discuss how darobactin-the first natural membrane protein inhibitor of Gram-negative bacteria identified in over five decades-selectively targets and specifically inhibits BamA. We conclude by deliberating how a detailed deduction of BAM complex-associated regulation of OMP biogenesis and OM remodeling will open avenues for the identification and development of effective next-generation therapeutics against Gram-negative pathogens.
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Affiliation(s)
- Anjana George
- Molecular Biophysics Laboratory, Department of Biological SciencesIndian Institute of Science Education and ResearchBhopalIndia
| | - Akanksha Gajanan Patil
- Molecular Biophysics Laboratory, Department of Biological SciencesIndian Institute of Science Education and ResearchBhopalIndia
| | - Radhakrishnan Mahalakshmi
- Molecular Biophysics Laboratory, Department of Biological SciencesIndian Institute of Science Education and ResearchBhopalIndia
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2
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Guest RL, Silhavy TJ. Cracking outer membrane biogenesis. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2023; 1870:119405. [PMID: 36455781 PMCID: PMC9878550 DOI: 10.1016/j.bbamcr.2022.119405] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2022] [Revised: 10/25/2022] [Accepted: 11/07/2022] [Indexed: 11/30/2022]
Abstract
The outer membrane is a distinguishing feature of the Gram-negative envelope. It lies on the external face of the peptidoglycan sacculus and forms a robust permeability barrier that protects extracytoplasmic structures from environmental insults. Overcoming the barrier imposed by the outer membrane presents a significant hurdle towards developing novel antibiotics that are effective against Gram-negative bacteria. As the outer membrane is an essential component of the cell, proteins involved in its biogenesis are themselves promising antibiotic targets. Here, we summarize key findings that have built our understanding of the outer membrane. Foundational studies describing the discovery and composition of the outer membrane as well as the pathways involved in its construction are discussed.
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Affiliation(s)
- Randi L Guest
- Department of Molecular Biology, Princeton University, Lewis Thomas Laboratory, Washington Road, Princeton, NJ, 08544, United States of America
| | - Thomas J Silhavy
- Department of Molecular Biology, Princeton University, Lewis Thomas Laboratory, Washington Road, Princeton, NJ, 08544, United States of America.
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3
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Fusco WG, Choudhary NR, Stewart SM, Alam SM, Sempowski GD, Elkins C, Leduc I. Defining Potential Vaccine Targets of Haemophilus ducreyi Trimeric Autotransporter Adhesin DsrA. Monoclon Antib Immunodiagn Immunother 2015; 34:73-82. [PMID: 25897604 PMCID: PMC4410285 DOI: 10.1089/mab.2014.0054] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2014] [Accepted: 09/08/2014] [Indexed: 01/06/2023] Open
Abstract
Haemophilus ducreyi is the causative agent of the sexually transmitted genital ulcer disease chancroid. Strains of H. ducreyi are grouped in two classes (I and II) based on genotypic and phenotypic differences, including those found in DsrA, an outer membrane protein belonging to the family of multifunctional trimeric autotransporter adhesins. DsrA is a key serum resistance factor of H. ducreyi that prevents binding of natural IgM at the bacterial surface and functions as an adhesin to fibronectin, fibrinogen, vitronectin, and human keratinocytes. Monoclonal antibodies (MAbs) were developed to recombinant DsrA (DsrA(I)) from prototypical class I strain 35000HP to define targets for vaccine and/or therapeutics. Two anti-DsrAI MAbs bound monomers and multimers of DsrA from genital and non-genital/cutaneous H. ducreyi strains in a Western blot and reacted to the surface of the genital strains; however, these MAbs did not recognize denatured or native DsrA from class II strains. In a modified extracellular matrix protein binding assay using viable H. ducreyi, one of the MAbs partially inhibited binding of fibronectin, fibrinogen, and vitronectin to class I H. ducreyi strain 35000HP, suggesting a role for anti-DsrA antibodies in preventing binding of H. ducreyi to extracellular matrix proteins. Standard ELISA and surface plasmon resonance using a peptide library representing full-length, mature DsrAI revealed the smallest nominal epitope bound by one of the MAbs to be MEQNTHNINKLS. Taken together, our findings suggest that this epitope is a potential target for an H. ducreyi vaccine.
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Affiliation(s)
- William G. Fusco
- Department of Medicine, University of North Carolina at Chapel Hill, North Carolina
| | - Neelima R. Choudhary
- Department of Medicine, University of North Carolina at Chapel Hill, North Carolina
| | - Shelley M. Stewart
- Duke Human Vaccine Institute, Duke University Medical Center, Durham, North Carolina
| | - S. Munir Alam
- Duke Human Vaccine Institute, Duke University Medical Center, Durham, North Carolina
| | - Gregory D. Sempowski
- Duke Human Vaccine Institute, Duke University Medical Center, Durham, North Carolina
| | - Christopher Elkins
- Department of Medicine, University of North Carolina at Chapel Hill, North Carolina
| | - Isabelle Leduc
- Department of Medicine, University of North Carolina at Chapel Hill, North Carolina
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4
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Lei J, Cai X, Ma X, Zhang L, Li Y, Dong X, St Geme J, Meng G. Recombinant expression, purification, crystallization and preliminary X-ray diffraction analysis of Haemophilus influenzae BamD and BamCD complex. Acta Crystallogr F Struct Biol Commun 2015; 71:234-8. [PMID: 25664802 PMCID: PMC4321482 DOI: 10.1107/s2053230x14027319] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2014] [Accepted: 12/15/2014] [Indexed: 11/11/2022] Open
Abstract
The Bam machinery, which is highly conserved from bacteria to humans, is well recognized as the apparatus responsible for the insertion and folding of most outer membrane proteins in Gram-negative bacteria. In Escherichia coli, the Bam machinery consists of five components (i.e. BamA, BamB, BamC, BamD and BamE). In comparison, there are only four partners in Haemophilus influenzae: a BamB homologue is not found in its genome. In this study, the recombinant expression, purification, crystallization and preliminary X-ray diffraction analysis of H. influenzae BamD and BamCD complex are reported. The genes encoding BamC and BamD were cloned into a pET vector and expressed in E. coli. Affinity, ion-exchange and gel-filtration chromatography were used to obtain high-purity protein for further crystallographic characterization. Using the hanging-drop vapour-diffusion technique, BamD and BamCD protein crystals of suitable size were obtained using protein concentrations of 70 and 50 mg ml(-1), respectively. Preliminary X-ray diffraction analysis showed that the BamD crystals diffracted to 4.0 Å resolution and belonged to space group P212121, with unit-cell parameters a = 54.5, b = 130.5, c = 154.7 Å. The BamCD crystals diffracted to 3.8 Å resolution and belonged to space group I212121, with unit-cell parameters a = 101.6, b = 114.1, c = 234.9 Å.
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Affiliation(s)
- Jintang Lei
- State Key Laboratory of Medical Genomics, Shanghai Institute of Hematology, Rui-Jin Hospital affiliated to Shanghai JiaoTong University School of Medicine, 197 Ruijin Er Road, Shanghai 200025, People’s Republic of China
| | - Xun Cai
- State Key Laboratory of Medical Genomics, Shanghai Institute of Hematology, Rui-Jin Hospital affiliated to Shanghai JiaoTong University School of Medicine, 197 Ruijin Er Road, Shanghai 200025, People’s Republic of China
| | - Xiaodan Ma
- State Key Laboratory of Medical Genomics, Shanghai Institute of Hematology, Rui-Jin Hospital affiliated to Shanghai JiaoTong University School of Medicine, 197 Ruijin Er Road, Shanghai 200025, People’s Republic of China
| | - Li Zhang
- State Key Laboratory of Medical Genomics, Shanghai Institute of Hematology, Rui-Jin Hospital affiliated to Shanghai JiaoTong University School of Medicine, 197 Ruijin Er Road, Shanghai 200025, People’s Republic of China
| | - Yuwen Li
- State Key Laboratory of Medical Genomics, Shanghai Institute of Hematology, Rui-Jin Hospital affiliated to Shanghai JiaoTong University School of Medicine, 197 Ruijin Er Road, Shanghai 200025, People’s Republic of China
| | - Xue Dong
- State Key Laboratory of Medical Genomics, Shanghai Institute of Hematology, Rui-Jin Hospital affiliated to Shanghai JiaoTong University School of Medicine, 197 Ruijin Er Road, Shanghai 200025, People’s Republic of China
| | - Joseph St Geme
- Department of Pediatrics, Children’s Hospital of Philadelphia and the Perelman School of Medicine at the University of Pennsylvania, Philadelphia, USA
| | - Guoyu Meng
- State Key Laboratory of Medical Genomics, Shanghai Institute of Hematology, Rui-Jin Hospital affiliated to Shanghai JiaoTong University School of Medicine, 197 Ruijin Er Road, Shanghai 200025, People’s Republic of China
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5
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Bos MP, Boxtel RTV, Tommassen J. Experimental Methods for Studying the BAM Complex in Neisseria meningitidis. Methods Mol Biol 2015; 1329:33-49. [PMID: 26427674 DOI: 10.1007/978-1-4939-2871-2_3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
Neisseria meningitidis is a human pathogen. It is intensively studied for host-pathogen interactions and vaccine development. However, its favorable growth properties, genetic accessibility, and small genome size also make it an excellent model organism for studying fundamental biological processes, such as outer membrane biogenesis. Indeed, the first component of the assembly machinery for outer-membrane proteins, the BAM complex, was identified in N. meningitidis. Here, we describe protocols to inactivate chromosomal genes and to express genes from a well-controlled promoter on a plasmid in N. meningitidis. Together, these protocols can be used, for example, to deplete cells from essential components of the BAM complex. We also describe a simple, gel-based assay to assess the proper functioning of the BAM complex in vivo.
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Affiliation(s)
- Martine P Bos
- Department of Molecular Microbiology and Institute of Biomembranes, Utrecht University, Padualaan 8, Utrecht, 3584 CH, The Netherlands
- Department of Medical Microbiology and Infection Control, VU University Medical Center, van der Boechorststraat 7, Amsterdam, 1081 BT, The Netherlands
| | - Ria Tommassen-van Boxtel
- Department of Molecular Microbiology and Institute of Biomembranes, Utrecht University, Padualaan 8, Utrecht, 3584 CH, The Netherlands
| | - Jan Tommassen
- Department of Molecular Microbiology and Institute of Biomembranes, Utrecht University, Padualaan 8, Utrecht, 3584 CH, The Netherlands.
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6
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7
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Fusco WG, Choudhary NR, Routh PA, Ventevogel MS, Smith VA, Koch GG, Almond GW, Orndorff PE, Sempowski GD, Leduc I. The Haemophilus ducreyi trimeric autotransporter adhesin DsrA protects against an experimental infection in the swine model of chancroid. Vaccine 2014; 32:3752-8. [PMID: 24844153 DOI: 10.1016/j.vaccine.2014.05.031] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2014] [Revised: 05/02/2014] [Accepted: 05/09/2014] [Indexed: 01/09/2023]
Abstract
Adherence of pathogens to cellular targets is required to initiate most infections. Defining strategies that interfere with adhesion is therefore important for the development of preventative measures against infectious diseases. As an adhesin to host extracellular matrix proteins and human keratinocytes, the trimeric autotransporter adhesin DsrA, a proven virulence factor of the Gram-negative bacterium Haemophilus ducreyi, is a potential target for vaccine development. A recombinant form of the N-terminal passenger domain of DsrA from H. ducreyi class I strain 35000HP, termed rNT-DsrAI, was tested as a vaccine immunogen in the experimental swine model of H. ducreyi infection. Viable homologous H. ducreyi was not recovered from any animal receiving four doses of rNT-DsrAI administered with Freund's adjuvant at two-week intervals. Control pigs receiving adjuvant only were all infected. All animals receiving the rNT-DsrAI vaccine developed antibody endpoint titers between 3.5 and 5 logs. All rNT-DsrAI antisera bound the surface of the two H. ducreyi strains used to challenge immunized pigs. Purified anti-rNT-DsrAI IgG partially blocked binding of fibrinogen at the surface of viable H. ducreyi. Overall, immunization with the passenger domain of the trimeric autotransporter adhesin DsrA accelerated clearance of H. ducreyi in experimental lesions, possibly by interfering with fibrinogen binding.
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Affiliation(s)
- William G Fusco
- Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Neelima R Choudhary
- Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Patty A Routh
- College of Veterinary Medicine, North Carolina State University, Raleigh, NC 27606, USA
| | - Melissa S Ventevogel
- Duke Human Vaccine Institute, Duke University Medical Center, Durham, NC 27710, USA
| | - Valerie A Smith
- Department of Biostatistics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Gary G Koch
- Department of Biostatistics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Glen W Almond
- College of Veterinary Medicine, North Carolina State University, Raleigh, NC 27606, USA
| | - Paul E Orndorff
- College of Veterinary Medicine, North Carolina State University, Raleigh, NC 27606, USA
| | - Gregory D Sempowski
- Duke Human Vaccine Institute, Duke University Medical Center, Durham, NC 27710, USA
| | - Isabelle Leduc
- Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
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8
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Kumar A, Yogisharadhya R, Ramakrishnan MA, Viswas K, Shivachandra SB. Structural analysis and cross-protective efficacy of recombinant 87 kDa outer membrane protein (Omp87) of Pasteurella multocida serogroup B:2. Microb Pathog 2013; 65:48-56. [DOI: 10.1016/j.micpath.2013.09.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2013] [Revised: 09/16/2013] [Accepted: 09/26/2013] [Indexed: 01/10/2023]
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Trimeric autotransporter DsrA is a major mediator of fibrinogen binding in Haemophilus ducreyi. Infect Immun 2013; 81:4443-52. [PMID: 24042118 DOI: 10.1128/iai.00743-13] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Haemophilus ducreyi is the etiologic agent of the sexually transmitted genital ulcer disease chancroid. In both natural and experimental chancroid, H. ducreyi colocalizes with fibrin at the base of the ulcer. Fibrin is obtained by cleavage of the serum glycoprotein fibrinogen (Fg) by thrombin to initiate formation of the blood clot. Fg binding proteins are critical virulence factors in medically important Gram-positive bacteria. H. ducreyi has previously been shown to bind Fg in an agglutination assay, and the H. ducreyi Fg binding protein FgbA was identified in ligand blotting with denatured proteins. To better characterize the interaction of H. ducreyi with Fg, we examined Fg binding to intact, viable H. ducreyi bacteria and identified a novel Fg binding protein. H. ducreyi bound unlabeled Fg in a dose-dependent manner, as measured by two different methods. In ligand blotting with total denatured cellular proteins, digoxigenin (DIG)-Fg bound only two H. ducreyi proteins, the trimeric autotransporter DsrA and the lectin DltA; however, only the isogenic dsrA mutant had significantly less cell-associated Fg than parental strains in Fg binding assays with intact bacteria. Furthermore, expression of DsrA, but not DltA or an empty vector, rendered the non-Fg-binding H. influenzae strain Rd capable of binding Fg. A 13-amino-acid sequence in the C-terminal section of the passenger domain of DsrA appears to be involved in Fg binding by H. ducreyi. Taken together, these data suggest that the trimeric autotransporter DsrA is a major determinant of Fg binding at the surface of H. ducreyi.
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Wedege E, Lie K, Bolstad K, Weynants VE, Halstensen A, Herstad TK, Kreutzberger J, Nome L, Naess LM, Aase A. Meningococcal omp85 in detergent-extracted outer membrane vesicle vaccines induces high levels of non-functional antibodies in mice. Scand J Immunol 2013; 77:452-9. [PMID: 23521186 DOI: 10.1111/sji.12051] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2012] [Accepted: 03/09/2013] [Indexed: 11/28/2022]
Abstract
The vaccine potential of meningococcal Omp85 was studied by comparing the immune responses of genetically modified deoxycholate-extracted outer membrane vesicles, expressing five-fold higher levels of Omp85, with wild-type vesicles. Groups (n = 6-12) of inbred and outbred mouse strains (Balb/c, C57BL/6, OFI and NMRI) were immunized with the two vaccines, and the induced antibody levels and bactericidal and opsonic activities measured. Except for Balb/c mice, which were low responders, the genetically modified vaccine raised high Omp85 antibody levels in all mouse strains. In comparison, the wild-type vaccine gave lower antibody levels, but NMRI mice responded to this vaccine with the same high levels as the modified vaccine in the other strains. Although the vaccines induced strain-dependent Omp85 antibody responses, the mouse strains showed high and similar serum bactericidal titres. Titres were negligible with heterologous or PorA-negative meningococcal target strains, demonstrating the presence of the dominant bactericidal PorA antibodies. The two vaccines induced the same opsonic titres. Thus, the genetically modified vaccine with high Omp85 antibody levels and the wild-type vaccine induced the same levels of functional activities related to protection against meningococcal disease, suggesting that meningococcal Omp85 is a less attractive vaccine antigen.
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Affiliation(s)
- E Wedege
- Division of Infectious Disease Control, Department of Bacteriology and Immunology, Norwegian Institute of Public Health, Oslo, Norway.
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Immunoproteomic analysis of the protective response obtained with subunit and commercial vaccines against Glässer's disease in pigs. Vet Immunol Immunopathol 2013; 151:235-47. [DOI: 10.1016/j.vetimm.2012.11.014] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2012] [Revised: 11/19/2012] [Accepted: 11/26/2012] [Indexed: 10/27/2022]
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12
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Klebba PE, Charbit A, Xiao Q, Jiang X, Newton SM. Mechanisms of iron and haem transport byListeria monocytogenes. Mol Membr Biol 2012; 29:69-86. [DOI: 10.3109/09687688.2012.694485] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
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13
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Rylev M, Abduljabar AB, Reinholdt J, Ennibi OK, Haubek D, Birkelund S, Kilian M. Proteomic and immunoproteomic analysis of Aggregatibacter actinomycetemcomitans JP2 clone strain HK1651. J Proteomics 2011; 74:2972-85. [PMID: 21867783 DOI: 10.1016/j.jprot.2011.07.022] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2011] [Revised: 06/06/2011] [Accepted: 07/24/2011] [Indexed: 11/25/2022]
Abstract
The proteome of Aggregatibacter actinomycetemcomitans HK1651 (JP2 clone) and immunoreactive antigens were studied by two-dimensional (2D) gel electrophoresis, matrix-assisted laser desorption time-of-flight mass spectrometry (MALDI-TOF-MS), and 2D immunoblotting. The highly leukotoxic JP2 clone of A. actinomycetemcomitans is strongly associated with aggressive periodontitis (AgP) in adolescents of North-West African descent and the pathogenicity of this bacterium is of major interest. Hence, we developed a comprehensive 2D proteome reference map of A. actinomycetemcomitans proteins with 167 identified spots representing 114 different proteins of which 15 were outer membrane proteins. To unravel immunoreactive antigens, we applied 2D-gel and subsequent immunoblotting analyses using sera from five individuals with A. actinomycetemcomitans infections and one healthy control. The analysis revealed 32 immunoreactive proteins. Antibodies to two outer membrane proteins, YaeT (85 kDa) and Omp39 (39 kDa), not previously described as immunoreactive, were found only in subjects with current or previous A. actinomycetemcomitans JP2 infection. Further proteome-based studies of A. actinomycetemcomitans combined with analyses of the humoral immune response and targeted against outer membrane proteins may provide important insight into the host relationship of this important pathogen.
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Affiliation(s)
- Mette Rylev
- Department of Medical Microbiology and Immunology, School of Dentistry, Faculty of Health Sciences, Aarhus University, Aarhus, Denmark.
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14
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Zhang W, Shao J, Liu G, Tang F, Lu Y, Zhai Z, Wang Y, Wu Z, Yao H, Lu C. Immunoproteomic analysis of bacterial proteins of Actinobacillus pleuropneumoniae serotype 1. Proteome Sci 2011; 9:32. [PMID: 21703014 PMCID: PMC3148531 DOI: 10.1186/1477-5956-9-32] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2010] [Accepted: 06/26/2011] [Indexed: 11/10/2022] Open
Abstract
Background Actinobacillus pleuropneumoniae (APP) is one of the most important swine pathogens worldwide. Identification and characterization of novel antigenic APP vaccine candidates are underway. In the present study, we use an immunoproteomic approach to identify APP protein antigens that may elicit an immune response in serotype 1 naturally infected swine and serotype 1 virulent strain S259-immunized rabbits. Results Proteins from total cell lysates of serotype 1 APP were separated by two-dimensional electrophoresis (2DE). Western blot analysis revealed 21 immunoreactive protein spots separated in the pH 4-7 range and 4 spots in the pH 7-11 range with the convalescent sera from swine; we found 5 immunoreactive protein spots that separated in the pH 4-7 range and 2 in the pH 7-11 range with hyperimmune sera from S259-immunized rabbits. The proteins included the known antigens ApxIIA, protective surface antigen D15, outer membrane proteins P5, subunit NqrA. The remaining antigens are being reported as immunoreactive proteins in APP for the first time, to our knowledge. Conclusions We identified a total of 42 immunoreactive proteins of the APP serotype 1 virulent strain S259 which represented 32 different proteins, including some novel immunoreactive factors which could be researched as vaccine candidates.
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Affiliation(s)
- Wei Zhang
- Key Laboratory of Animal Disease Diagnostic & Immunology, Ministry of Agriculture, Nanjing Agricultural University, Nanjing 210095, China
| | - Jing Shao
- Key Laboratory of Animal Disease Diagnostic & Immunology, Ministry of Agriculture, Nanjing Agricultural University, Nanjing 210095, China
| | - Guangjin Liu
- Key Laboratory of Animal Disease Diagnostic & Immunology, Ministry of Agriculture, Nanjing Agricultural University, Nanjing 210095, China
| | - Fang Tang
- Key Laboratory of Animal Disease Diagnostic & Immunology, Ministry of Agriculture, Nanjing Agricultural University, Nanjing 210095, China
| | - Yan Lu
- Key Laboratory of Animal Disease Diagnostic & Immunology, Ministry of Agriculture, Nanjing Agricultural University, Nanjing 210095, China
| | - Zhipeng Zhai
- Key Laboratory of Animal Disease Diagnostic & Immunology, Ministry of Agriculture, Nanjing Agricultural University, Nanjing 210095, China
| | - Yang Wang
- Key Laboratory of Animal Disease Diagnostic & Immunology, Ministry of Agriculture, Nanjing Agricultural University, Nanjing 210095, China
| | - Zongfu Wu
- Key Laboratory of Animal Disease Diagnostic & Immunology, Ministry of Agriculture, Nanjing Agricultural University, Nanjing 210095, China
| | - Huochun Yao
- Key Laboratory of Animal Disease Diagnostic & Immunology, Ministry of Agriculture, Nanjing Agricultural University, Nanjing 210095, China
| | - Chengping Lu
- Key Laboratory of Animal Disease Diagnostic & Immunology, Ministry of Agriculture, Nanjing Agricultural University, Nanjing 210095, China
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15
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Passive immunization with a polyclonal antiserum to the hemoglobin receptor of Haemophilus ducreyi confers protection against a homologous challenge in the experimental swine model of chancroid. Infect Immun 2011; 79:3168-77. [PMID: 21646451 DOI: 10.1128/iai.00017-11] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Haemophilus ducreyi, the etiologic agent of chancroid, has an obligate requirement for heme. Heme is acquired by H. ducreyi from its human host via TonB-dependent transporters expressed at its bacterial surface. Of 3 TonB-dependent transporters encoded in the genome of H. ducreyi, only the hemoglobin receptor, HgbA, is required to establish infection during the early stages of the experimental human model of chancroid. Active immunization with a native preparation of HgbA (nHgbA) confers complete protection in the experimental swine model of chancroid, using either Freund's or monophosphoryl lipid A as adjuvants. To determine if transfer of anti-nHgbA serum is sufficient to confer protection, a passive immunization experiment using pooled nHgbA antiserum was conducted in the experimental swine model of chancroid. Pigs receiving this pooled nHgbA antiserum were protected from a homologous, but not a heterologous, challenge. Passively transferred polyclonal antibodies elicited to nHgbA bound the surface of H. ducreyi and partially blocked hemoglobin binding by nHgbA, but were not bactericidal. Taken together, these data suggest that the humoral immune response to the HgbA vaccine is protective against an H. ducreyi infection, possibly by preventing acquisition of the essential nutrient heme.
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16
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Tommassen J. Assembly of outer-membrane proteins in bacteria and mitochondria. Microbiology (Reading) 2010; 156:2587-2596. [DOI: 10.1099/mic.0.042689-0] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The cell envelope of Gram-negative bacteria consists of two membranes separated by the periplasm. In contrast with most integral membrane proteins, which span the membrane in the form of hydrophobicα-helices, integral outer-membrane proteins (OMPs) formβ-barrels. Similarβ-barrel proteins are found in the outer membranes of mitochondria and chloroplasts, probably reflecting the endosymbiont origin of these eukaryotic cell organelles. How theseβ-barrel proteins are assembled into the outer membrane has remained enigmatic for a long time. In recent years, much progress has been reached in this field by the identification of the components of the OMP assembly machinery. The central component of this machinery, called Omp85 or BamA, is an essential and highly conserved bacterial protein that recognizes a signature sequence at the C terminus of its substrate OMPs. A homologue of this protein is also found in mitochondria, where it is required for the assembly ofβ-barrel proteins into the outer membrane as well. Although accessory components of the machineries are different between bacteria and mitochondria, a mitochondrialβ-barrel OMP can be assembled into the bacterial outer membrane and, vice versa, bacterial OMPs expressed in yeast are assembled into the mitochondrial outer membrane. These observations indicate that the basic mechanism of OMP assembly is evolutionarily highly conserved.
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Affiliation(s)
- Jan Tommassen
- Department of Molecular Microbiology and Institute of Biomembranes, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
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Identification of an Edwardsiella tarda surface antigen and analysis of its immunoprotective potential as a purified recombinant subunit vaccine and a surface-anchored subunit vaccine expressed by a fish commensal strain. Vaccine 2010; 28:6603-8. [DOI: 10.1016/j.vaccine.2010.07.050] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2010] [Revised: 06/24/2010] [Accepted: 07/15/2010] [Indexed: 11/20/2022]
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Lenhart TR, Akins DR. Borrelia burgdorferi locus BB0795 encodes a BamA orthologue required for growth and efficient localization of outer membrane proteins. Mol Microbiol 2009; 75:692-709. [PMID: 20025662 DOI: 10.1111/j.1365-2958.2009.07015.x] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The outer membrane (OM) of the pathogenic diderm spirochete, Borrelia burgdorferi, contains integral beta-barrel outer membrane proteins (OMPs) in addition to its numerous outer surface lipoproteins. Very few OMPs have been identified in B. burgdorferi, and the protein machinery required for OMP assembly and OM localization is currently unknown. Essential OM BamA proteins have recently been characterized in Gram-negative bacteria that are central components of an OM beta-barrel assembly machine and are required for proper localization and insertion of bacterial OMPs. In the present study, we characterized a putative B. burgdorferi BamA orthologue encoded by open reading frame bb0795. Structural model predictions and cellular localization data indicate that the B. burgdorferi BB0795 protein contains an N-terminal periplasmic domain and a C-terminal, surface-exposed beta-barrel domain. Additionally, assays with an IPTG-regulatable bb0795 mutant revealed that BB0795 is required for B. burgdorferi growth. Furthermore, depletion of BB0795 results in decreased amounts of detectable OMPs in the B. burgdorferi OM. Interestingly, a decrease in the levels of surface-exposed lipoproteins was also observed in the mutant OMs. Collectively, our structural, cellular localization and functional data are consistent with the characteristics of other BamA proteins, indicating that BB0795 is a B. burgdorferi BamA orthologue.
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Affiliation(s)
- Tiffany R Lenhart
- Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
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19
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Liao Y, Deng J, Zhang A, Zhou M, Hu Y, Chen H, Jin M. Immunoproteomic analysis of outer membrane proteins and extracellular proteins of Actinobacillus pleuropneumoniae JL03 serotype 3. BMC Microbiol 2009; 9:172. [PMID: 19695095 PMCID: PMC2741471 DOI: 10.1186/1471-2180-9-172] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2009] [Accepted: 08/20/2009] [Indexed: 11/18/2022] Open
Abstract
Background Actinobacillus pleuropneumoniae is the causative agent of porcine contagious pleuropneumonia, a highly contagious respiratory infection in pigs, and all the 15 serotypes are able to cause disease. Current vaccines including subunit vaccines could not provide satisfactory protection against A. pleuropneumoniae. In this study, the immunoproteomic approach was applied to the analysis of extracellular and outer membrane proteins of A. pleuropneumoniae JL03 serotype 3 for the identification of novel immunogenic proteins for A. pleuropneumoniae. Results A total of 30 immunogenic proteins were identified from outer membrane and extracellular proteins of JL03 serotype 3, of which 6 were known antigens and 24 were novel immunogenic proteins for A. pleuropneumoniae. Conclusion These data provide information about novel immunogenic proteins for A. pleuropneumoniae serotype 3, and are expected to aid in development of novel vaccines against A. pleuropneumoniae.
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Affiliation(s)
- Yonghong Liao
- College of Veterinary Medicine, Huazhong Agricultural University, Hubei, PR China.
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20
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Zhou M, Guo Y, Zhao J, Hu Q, Hu Y, Zhang A, Chen H, Jin M. Identification and characterization of novel immunogenic outer membrane proteins of Haemophilus parasuis serovar 5. Vaccine 2009; 27:5271-7. [DOI: 10.1016/j.vaccine.2009.06.051] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2009] [Revised: 06/11/2009] [Accepted: 06/11/2009] [Indexed: 10/20/2022]
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21
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Gouré J, Findlay WA, Deslandes V, Bouevitch A, Foote SJ, MacInnes JI, Coulton JW, Nash JHE, Jacques M. Microarray-based comparative genomic profiling of reference strains and selected Canadian field isolates of Actinobacillus pleuropneumoniae. BMC Genomics 2009; 10:88. [PMID: 19239696 PMCID: PMC2653537 DOI: 10.1186/1471-2164-10-88] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2008] [Accepted: 02/24/2009] [Indexed: 11/12/2022] Open
Abstract
Background Actinobacillus pleuropneumoniae, the causative agent of porcine pleuropneumonia, is a highly contagious respiratory pathogen that causes severe losses to the swine industry worldwide. Current commercially-available vaccines are of limited value because they do not induce cross-serovar immunity and do not prevent development of the carrier state. Microarray-based comparative genomic hybridizations (M-CGH) were used to estimate whole genomic diversity of representative Actinobacillus pleuropneumoniae strains. Our goal was to identify conserved genes, especially those predicted to encode outer membrane proteins and lipoproteins because of their potential for the development of more effective vaccines. Results Using hierarchical clustering, our M-CGH results showed that the majority of the genes in the genome of the serovar 5 A. pleuropneumoniae L20 strain were conserved in the reference strains of all 15 serovars and in representative field isolates. Fifty-eight conserved genes predicted to encode for outer membrane proteins or lipoproteins were identified. As well, there were several clusters of diverged or absent genes including those associated with capsule biosynthesis, toxin production as well as genes typically associated with mobile elements. Conclusion Although A. pleuropneumoniae strains are essentially clonal, M-CGH analysis of the reference strains of the fifteen serovars and representative field isolates revealed several classes of genes that were divergent or absent. Not surprisingly, these included genes associated with capsule biosynthesis as the capsule is associated with sero-specificity. Several of the conserved genes were identified as candidates for vaccine development, and we conclude that M-CGH is a valuable tool for reverse vaccinology.
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Affiliation(s)
- Julien Gouré
- Groupe de Recherche sur les Maladies Infectieuses du Porc, Université de Montréal, St-Hyacinthe, Québec, Canada.
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22
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Highly conserved surface proteins of oral spirochetes as adhesins and potent inducers of proinflammatory and osteoclastogenic factors. Infect Immun 2008; 76:2428-38. [PMID: 18390996 DOI: 10.1128/iai.01128-07] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Oral spirochetes include enormously heterogeneous Treponema species, and some have been implicated in the etiology of periodontitis. In this study, we characterized highly conserved surface proteins in four representative oral spirochetes (Treponema denticola, T. lecithinolyticum, T. maltophilum, and T. socranskii subsp. socranskii) that are homologs of T. pallidum Tp92, with opsonophagocytic potential and protective capacity against syphilis. Tp92 homologs of oral spirochetes had predicted signal peptides (20 to 31 amino acids) and molecular masses of 88 to 92 kDa for mature proteins. They showed amino acid sequence identities of 37.9 to 49.3% and similarities of 54.5 to 66.9% to Tp92. The sequence identities and similarities of Tp92 homologs of oral treponemes to one another were 41.6 to 71.6% and 59.9 to 85.6%, respectively. The tp92 gene homologs were successfully expressed in Escherichia coli, and the recombinant proteins were capable of binding to KB cells, an epithelial cell line, and inhibited the binding of the whole bacteria to the cells. Antiserum (the immunoglobulin G fraction) raised against a recombinant form of the T. denticola Tp92 homolog cross-reacted with homologs from three other species of treponemes. The Tp92 homologs stimulated various factors involved in inflammation and osteoclastogenesis, like interleukin-1beta (IL-1beta), tumor necrosis factor alpha, IL-6, prostaglandin E(2), and matrix metalloproteinase 9, in host cells like monocytes and fibroblasts. Our results demonstrate that Tp92 homologs of oral spirochetes are highly conserved and may play an important role in cell attachment, inflammation, and tissue destruction. The coexistence of various Treponema species in a single periodontal pocket and, therefore, the accumulation of multiple Tp92 homologs may amplify the pathological effect in periodontitis.
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Afonina G, Leduc I, Nepluev I, Jeter C, Routh P, Almond G, Orndorff PE, Hobbs M, Elkins C. Immunization with the Haemophilus ducreyi hemoglobin receptor HgbA protects against infection in the swine model of chancroid. Infect Immun 2006; 74:2224-32. [PMID: 16552053 PMCID: PMC1418891 DOI: 10.1128/iai.74.4.2224-2232.2006] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
The etiologic agent of chancroid is Haemophilus ducreyi. To fulfill its obligate requirement for heme, H. ducreyi uses two TonB-dependent receptors: the hemoglobin receptor (HgbA) and a receptor for free heme (TdhA). Expression of HgbA is necessary for H. ducreyi to survive and initiate disease in a human model of chancroid. In this study, we used a swine model of H. ducreyi infection to demonstrate that an experimental HgbA vaccine efficiently prevents chancroid, as determined by several parameters. Histological sections of immunized animals lacked typical microscopic features of chancroid. All inoculated sites from mock-immunized pigs yielded viable H. ducreyi cells, whereas no viable H. ducreyi cells were recovered from inoculated sites of HgbA-immunized pigs. Antibodies from sera of HgbA-immunized animals bound to and initiated antibody-dependent bactericidal activity against homologous H. ducreyi strain 35000HP and heterologous strain CIP542 ATCC; however, an isogenic hgbA mutant of 35000HP was not killed, proving specificity. Anti-HgbA immunoglobulin G blocked hemoglobin binding to the HgbA receptor, suggesting a novel mechanism of protection through the limitation of heme/iron acquisition by H. ducreyi. Such a vaccine strategy might be applied to other bacterial pathogens with strict heme/iron requirements. Taken together, these data suggest continuing the development of an HgbA subunit vaccine to prevent chancroid.
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Affiliation(s)
- Galyna Afonina
- Department of Medicine, School of Medicine, University of North Carolina, Chapel Hill, NC 27599, USA.
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24
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Abstract
Omp85 is a protein found in Gram-negative bacteria where it serves to integrate proteins into the bacterial outer membrane. Members of the Omp85 family of proteins are defined by the presence of two domains: an N-terminal, periplasmic domain rich in POTRA repeats and a C-terminal beta-barrel domain embedded in the outer membrane. The widespread distribution of Omp85 family members together with their fundamental role in outer membrane assembly suggests the ancestral Omp85 arose early in the evolution of prokaryotic cells. Mitochondria, derived from an ancestral bacterial endosymbiont, also use a member of the Omp85 family to assemble proteins in their outer membranes. More distant relationships are seen between the Omp85 family and both the core proteins in two-partner secretion systems and the Toc75 family of protein translocases found in plastid outer envelopes. Aspects of the ancestry and molecular architecture of the Omp85 family of proteins is providing insight into the mechanism by which proteins might be integrated and assembled into bacterial outer membranes.
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Affiliation(s)
- Ian E Gentle
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville 3010, Australia
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25
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The Future Role of Vaccines and Microbicides. Sex Transm Dis 2006. [DOI: 10.1007/978-1-59745-040-9_16] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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26
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Abstract
The outer membrane is the first line of contact between Gram-negative bacteria and their external environment. Embedded in the outer membrane are integral outer membrane proteins (OMPs) that perform a diverse range of tasks. OMPs are synthesized in the cytoplasm and are translocated across the inner membrane and probably diffuse through the periplasm before they are inserted into the outer membrane in a folded and biologically active form. Passage through the periplasm presents a number of challenges, due to the hydrophobic nature of the OMPs and the choice of membranes into which they can insert. Recently, a number of periplasmic proteins and one OMP have been shown to play a role in OMP biogenesis. In this review, we describe what is known about these folding factors and how they function in a biological context. In particular, we focus on how they interact with the OMPs at the molecular level and present a comprehensive overview of data relating to a possible effect on OMP folding yield and kinetics. Furthermore, we discuss the role of lipo-chaperones, i.e. lipopolysaccharide and phospholipids, in OMP folding. Important advances have clearly been made in the field, but much work remains to be done, particularly in terms of describing the biophysical basis for the chaperone-OMP interactions which so intricately regulate OMP biogenesis.
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Affiliation(s)
- Jesper E Mogensen
- Department of Life Sciences, Aalborg University, Sohngaardsholmsvej 49, DK-9000 Aalborg, Denmark.
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27
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Roy-Leon JE, Lauzon WD, Toye B, Singhal N, Cameron DW. In vitro and in vivo activity of combination antimicrobial agents on Haemophilus ducreyi. J Antimicrob Chemother 2005; 56:552-8. [PMID: 16046468 DOI: 10.1093/jac/dki270] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
OBJECTIVES Development of single dose antibiotic treatments for chancroid has been followed by drug-resistant Haemophilus ducreyi in endemic areas. We examined the activity and interactions of antimicrobial agents and combinations against H. ducreyi. METHODS We evaluated the in vitro susceptibility of three virulent strains of H. ducreyi to ceftriaxone, azithromycin, rifabutin and streptomycin, and each two-drug combination by the agar dilution method. We then tested each two-antibiotic combination for activity by the chequerboard method. Lastly, we chose the antibiotic combination with the lowest fractional inhibitory concentration index (FICI) and tested combined sub-therapeutic doses, the highest doses which had no effect alone on lesion healing compared with controls, for in vivo interaction in the temperature-dependent rabbit model of H. ducreyi infection. RESULTS Each H. ducreyi strain was susceptible in vitro to each antibiotic and two-antibiotic combination, and combined ceftriaxone and streptomycin had the lowest FICI at 0.63. In five treated animals versus three untreated controls, combined sub-therapeutic doses of ceftriaxone (0.05 mg/kg) and streptomycin (10 mg/kg) reduced mean (SD) duration of culture positivity from 7.3 (1.1) to 2.6 (1.7) days (P<0.001), time to 50% reduction in lesion size from 9.7 (1.5) to 5.8 (0.8) days (P<0.005), and time to resolution of ulcer from 11.7 (2.3) to 6.6 (1.7) days (P<0.05). CONCLUSIONS Ceftriaxone and streptomycin have in vivo synergic interaction against H. ducreyi lesions in the temperature-dependent rabbit model of infection. Antibiotic combinations may be evaluated clinically as single-dose therapy for chancroid.
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Affiliation(s)
- Josée E Roy-Leon
- Faculty of Medicine, Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Canada
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28
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Doerrler WT, Raetz CRH. Loss of outer membrane proteins without inhibition of lipid export in an Escherichia coli YaeT mutant. J Biol Chem 2005; 280:27679-87. [PMID: 15951436 DOI: 10.1074/jbc.m504796200] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Escherichia coli yaeT encodes an essential, conserved outer membrane (OM) protein that is an ortholog of Neisseria meningitidis Omp85. Conflicting data with N. meningitidis indicate that Omp85 functions either in assembly of OM proteins or in export of OM lipids. The role of YaeT in E. coli was investigated with a new temperature-sensitive mutant harboring nine amino acid substitutions. The mutant stops growing after 60 min at 44 degrees C. After 30 min at 44 degrees C, incorporation of [35S]methionine into newly synthesized OM proteins is selectively inhibited. Synthesis and export of OM phospholipids and lipopolysaccharide are not impaired. OM protein levels are low, even at 30 degrees C, and the buoyant density of the OM is correspondingly lower. By Western blotting, we show that levels of the major OM protein OmpA are lower in the mutant in whole cells, membranes, and the growth medium. SecA functions as a multicopy suppressor of the temperature-sensitive phenotype and partially restores OM proteins. Our data are consistent with a critical role for YaeT in OM protein assembly in E. coli.
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Affiliation(s)
- William T Doerrler
- Department of Biochemistry, Duke University Medical Center, Durham, North Carolina 27710, USA
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29
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White CD, Leduc I, Olsen B, Jeter C, Harris C, Elkins C. Haemophilus ducreyi Outer membrane determinants, including DsrA, define two clonal populations. Infect Immun 2005; 73:2387-99. [PMID: 15784585 PMCID: PMC1087395 DOI: 10.1128/iai.73.4.2387-2399.2005] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The Haemophilus ducreyi outer membrane component DsrA (for ducreyi serum resistance A) is necessary for complete resistance to normal human serum (NHS). When DsrA expression in 19 temporally and geographically diverse clinical isolates of H. ducreyi was examined by Western blotting, 5 of the strains expressed a different immunotype of the DsrA protein (DsrA(II)) than the well-characterized prototypical strain 35000HP (DsrA(I)). The predicted DsrA proteins expressed by the DsrA(II) strains were 100% identical to each other but only 48% identical to that of strain 35000HP. In addition to the DsrA(II) protein, class II strains also expressed variant forms of other outer membrane proteins (OMPs) including NcaA (necessary for collagen adhesion A), DltA (ducreyi lectin A), Hlp (H. ducreyi lipoprotein), major OMP, and/or OmpA2 (for OMP A2) and synthesized a distinct, faster-migrating lipooligosaccharide. Based on these data, strains expressing DsrA(I) were termed class I, and those expressing DsrA(II) were termed class II. Expression of dsrA(II) from strain CIP 542 ATCC in the class I dsrA(I) mutant FX517 (35000HP background), which does not express a DsrA protein, rendered this strain resistant to 50% NHS. This demonstrates that DsrA(II) protein is also critical to serum resistance. Taken together, these results indicate that there are two clonal populations of H. ducreyi. The implications of two classes of H. ducreyi strains differing in important antigenic outer membrane components are discussed.
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Affiliation(s)
- Catherine Dinitra White
- Department of Medicine, School of Medicine, University of North Carolina, Chapel Hill, NC 27599, USA
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30
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Ashby D, Leduc I, Lauzon W, Lee BC, Singhal N, Cameron DW. Attenuated Salmonella typhimurium SL3261 as a vaccine vector for recombinant antigen in rabbits. J Immunol Methods 2005; 299:153-64. [PMID: 15914198 DOI: 10.1016/j.jim.2005.02.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2004] [Revised: 02/02/2005] [Accepted: 02/15/2005] [Indexed: 10/25/2022]
Abstract
Oral live Salmonella vaccine vectors expressing recombinant guest antigens help stimulate systemic, mucosal, humoral, and cell-mediated immune responses against Salmonella and recombinant antigens. It may be possible to use them effectively against Haemophilus ducreyi, the bacterium that causes chancroid, a sexually transmitted genital ulcer disease. This study aimed to test the feasibility of using oral Salmonella vaccine vectors for the evaluation of chancroid vaccine candidates in the temperature-dependent rabbit model of H. ducreyi infection, an in vivo quantitative virulence assay of inducible immunity. We identified 10(8) to 10(9) CFU to be a safe and immunogenic oral dose range of S. typhimurium SL3261, by monitoring post-administration onset and course of illness and antibody titre by enzyme immunoassay (EIA). We successfully transduced plasmid pTETnir15 into the strain to produce recombinant S. typhimurium SL3261(pTETnir15), successfully expressed tetanus toxin fragment C (TetC) in it, and elicited serum anti-TetC titres of 1:6400 by EIA, 4 weeks after inoculation. The course of experimentally induced H. ducreyi skin lesions in rabbits treated with SL3261(pTETnir15) was similar to that in saline-treated controls. We describe a framework that successfully uses Salmonella as a vector for recombinant control antigen in the rabbit model of H. ducreyi infection, and is suitable for pre-clinical evaluation of Salmonella vector-based H. ducreyi vaccine antigen candidates.
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Affiliation(s)
- Deborah Ashby
- Department of Biochemistry, Microbiology, and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, Canada
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31
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Leduc I, Richards P, Davis C, Schilling B, Elkins C. A novel lectin, DltA, is required for expression of a full serum resistance phenotype in Haemophilus ducreyi. Infect Immun 2004; 72:3418-28. [PMID: 15155648 PMCID: PMC415671 DOI: 10.1128/iai.72.6.3418-3428.2004] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Haemophilus ducreyi, the causative agent of chancroid, is highly resistant to the complement-mediated bactericidal activity of normal human serum (NHS). Previously, we identified DsrA (for ducreyi serum resistance A), a major factor required for expression of the serum resistance phenotype in H. ducreyi. We describe here a second outer membrane protein, DltA (for ducreyi lectin A), which also contributes to serum resistance in H. ducreyi. Isogenic dltA mutants, constructed in 35000HP wild-type and FX517 dsrA backgrounds, were more susceptible to the bactericidal effects of NHS than each respective parent, demonstrating the additive effect of the mutations. Furthermore, expression of dltA in H. influenzae strain Rd rendered this highly susceptible strain partially resistant to 5% NHS compared to a vector-control strain. Although primary basic local alignment search tool analysis of the dltA open reading frame revealed no close bacterial homologue, similarity to the beta-chain of the eukaryotic lectin ricin was noted. DltA shares highly conserved structural motifs with the ricin beta chain, such as cysteines and lectin-binding domains. To determine whether dltA was a lectin, ligand blots and affinity chromatography experiments were performed. DltA was affinity purified on immobilized lactose and N-acetylgalactosamine, and N-glycosylated but not glycosidase-treated model glycoproteins bound DltA. These data indicate that DltA is a lectin with specificity for lactose-related carbohydrates (CHO) and is important for H. ducreyi serum resistance.
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Affiliation(s)
- Isabelle Leduc
- Department of Medicine, School of Medicine, University of North Carolina, Chapel Hill, North Carolina 27599, USA
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Voulhoux R, Bos MP, Geurtsen J, Mols M, Tommassen J. Role of a highly conserved bacterial protein in outer membrane protein assembly. Science 2003; 299:262-5. [PMID: 12522254 DOI: 10.1126/science.1078973] [Citation(s) in RCA: 571] [Impact Index Per Article: 27.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
After transport across the cytoplasmic membrane, bacterial outer membrane proteins are assembled into the outer membrane. Meningococcal Omp85 is a highly conserved protein in Gram-negative bacteria, and its homolog Toc75 is a component of the chloroplast protein-import machinery. Omp85 appeared to be essential for viability, and unassembled forms of various outer membrane proteins accumulated upon Omp85 depletion. Immunofluorescence microscopy revealed decreased surface exposure of outer membrane proteins, which was particularly apparent at the cell-division planes. Thus, Omp85 is likely to play a role in outer membrane protein assembly.
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Affiliation(s)
- Romé Voulhoux
- Department of Molecular Microbiology and Institute of Biomembranes, Utrecht University, 3584 CH Utrecht, Netherlands
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34
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Patterson K, Olsen B, Thomas C, Norn D, Tam M, Elkins C. Development of a rapid immunodiagnostic test for Haemophilus ducreyi. J Clin Microbiol 2002; 40:3694-702. [PMID: 12354868 PMCID: PMC130854 DOI: 10.1128/jcm.40.10.3694-3702.2002] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2002] [Revised: 04/11/2002] [Accepted: 06/28/2002] [Indexed: 01/06/2023] Open
Abstract
Haemophilus ducreyi is the etiologic agent of chancroid, a sexually transmitted disease that increases the rate of transmission of human immunodeficiency virus. Chancroid ulcerations are difficult to distinguish from those produced by syphilis and herpes. Diagnosis based solely on clinical grounds is inaccurate, and culture is insensitive. Highly sensitive PCR has largely superseded culture as the preferred method of laboratory diagnosis; however, neither culture nor PCR is feasible where chancroid is endemic. We developed a rapid (15-min) diagnostic test based on monoclonal antibodies (MAbs) to the hemoglobin receptor of H. ducreyi, HgbA. This outer membrane protein is conserved in all strains of H. ducreyi tested and is required for the establishment of experimental human infection. MAbs to HgbA were generated and tested for cross-reactivity against a panel of geographically diverse strains. Three MAbs were found to be unique and noncompetitive and bound to all strains of H. ducreyi tested. Using an immunochromatography format, we evaluated the sensitivity and specificity of the test using geographically diverse strains of H. ducreyi, other Haemophilus strains, and other bacteria known to superinfect genital ulcers. All H. ducreyi strains were positive, and all other bacteria were negative, resulting in a specificity of 100%. The minimum number of CFU of H. ducreyi detected was 2 x 10(6) CFU, and the minimum amount of purified HgbA protein detected was 8.5 ng. Although this level of sensitivity may not be sufficient to detect H. ducreyi in all clinical specimens, further work to increase the sensitivity could potentially make this a valuable bedside tool in areas where chancroid is endemic.
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Affiliation(s)
- Kristine Patterson
- Department of Medicine, Division of Infectious Diseases, University of North Carolina, 547 Burnett-Womack Building, Chapel Hill, NC 27599-7030, USA
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35
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Spinola SM, Bauer ME, Munson RS. Immunopathogenesis of Haemophilus ducreyi infection (chancroid). Infect Immun 2002; 70:1667-76. [PMID: 11895928 PMCID: PMC127820 DOI: 10.1128/iai.70.4.1667-1676.2002] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Affiliation(s)
- Stanley M Spinola
- Department of Medicine, School of Medicine, Indiana University, Indianapolis, Indiana 46202, USA.
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