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Haque S, Sengupta S, Khan A, Mukhopadhyay AK, Bhan MK, Kumar R, Jailkhani B. Immune response of S. Typhi-derived Vi polysaccharide and outer membrane protein a conjugate in mice. Pediatr Neonatol 2023; 64:518-527. [PMID: 36868948 DOI: 10.1016/j.pedneo.2022.12.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Revised: 12/06/2022] [Accepted: 12/20/2022] [Indexed: 02/19/2023] Open
Abstract
Typhoid fever is a serious concern precisely in developing nations. Still investigators are exploring a better conjugate partner for Vi-polysaccharide to develop a more effective vaccine for typhoid fever. Here, we cloned and expressed S. Typhi outer membrane protein A (OmpA). The conjugation of Vi-polysaccharide with OmpA was carried out by the carbodiimide (EDAC) method employing ADH as a linker. Total Ig and IgG generated against OmpA, and Vi polysaccharide was quantified by ELISA. Vi polysaccharide alone induced very low levels of Vi polysaccharide antibody. Vi-OmpA conjugate (Vi-conjugate) elicited a robust immune response compared to Vi polysaccharide alone and showed booster response. Further, IgG was only evoked by Vi-OmpA conjugate, not with Vi polysaccharide alone. OmpA antibody induction in both the Vi-OmpA conjugate and OmpA were similar level. Taken together, we show that OmpA as a carrier protein conjugated to Vi polysaccharide is immunogenic. We predict OmpA antibodies will contribute protection along with antibodies generated by Vi-polysaccharide. Past and current literature supports that OmpA is highly conserved protein not only among Salmonellae but entire Enterobacteriacea family with 96-100% identity.
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Affiliation(s)
- Shabirul Haque
- Department of Autoimmune Diseases, Feinstein Institute for Medical Research, Northwell Health, 350 Community Drive, Manhasset, NY, 11030, USA; Department of Laboratory Medicine, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, India.
| | - Sanjukta Sengupta
- Department of Laboratory Medicine, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, India
| | - Azhar Khan
- Faculty of Applied Sciences and Biotechnology, Shoolini University, Solan, Himachal Pradesh, India
| | - Asok Kumar Mukhopadhyay
- Department of Laboratory Medicine, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, India
| | - Maharaj Kishan Bhan
- Department of Pediatrics, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, India
| | - Ramesh Kumar
- Department of Pediatrics, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, India
| | - Bansilal Jailkhani
- Department of Laboratory Medicine, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, India
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Regulation of OmpA Translation and Shigella dysenteriae Virulence by an RNA Thermometer. Infect Immun 2020; 88:IAI.00871-19. [PMID: 31792074 DOI: 10.1128/iai.00871-19] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Accepted: 11/25/2019] [Indexed: 12/20/2022] Open
Abstract
RNA thermometers are cis-acting riboregulators that mediate the posttranscriptional regulation of gene expression in response to environmental temperature. Such regulation is conferred by temperature-responsive structural changes within the RNA thermometer that directly result in differential ribosomal binding to the regulated transcript. The significance of RNA thermometers in controlling bacterial physiology and pathogenesis is becoming increasingly clear. This study combines in silico, molecular genetics, and biochemical analyses to characterize both the structure and function of a newly identified RNA thermometer within the ompA transcript of Shigella dysenteriae First identified by in silico structural predictions, genetic analyses have demonstrated that the ompA RNA thermometer is a functional riboregulator sufficient to confer posttranscriptional temperature-dependent regulation, with optimal expression observed at the host-associated temperature of 37°C. Structural studies and ribosomal binding analyses have revealed both increased exposure of the ribosomal binding site and increased ribosomal binding to the ompA transcript at permissive temperatures. The introduction of site-specific mutations predicted to alter the temperature responsiveness of the ompA RNA thermometer has predictable consequences for both the structure and function of the regulatory element. Finally, in vitro tissue culture-based analyses implicate the ompA RNA thermometer as a bona fide S. dysenteriae virulence factor in this bacterial pathogen. Given that ompA is highly conserved among Gram-negative pathogens, these studies not only provide insight into the significance of riboregulation in controlling Shigella virulence, but they also have the potential to facilitate further understanding of the physiology and/or pathogenesis of a wide range of bacterial species.
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Gupta D, Sutherland MC, Rengasamy K, Meacham JM, Kranz RG, Bose A. Photoferrotrophs Produce a PioAB Electron Conduit for Extracellular Electron Uptake. mBio 2019; 10:e02668-19. [PMID: 31690680 PMCID: PMC6831781 DOI: 10.1128/mbio.02668-19] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Accepted: 10/10/2019] [Indexed: 11/20/2022] Open
Abstract
Photoferrotrophy is a form of anoxygenic photosynthesis whereby bacteria utilize soluble or insoluble forms of ferrous iron as an electron donor to fix carbon dioxide using light energy. They can also use poised electrodes as their electron donor via phototrophic extracellular electron uptake (phototrophic EEU). The electron uptake mechanisms underlying these processes are not well understood. Using Rhodopseudomonas palustris TIE-1 as a model, we show that a single periplasmic decaheme cytochrome c, PioA, and an outer membrane porin, PioB, form a complex allowing extracellular electron uptake across the outer membrane from both soluble iron and poised electrodes. We observe that PioA undergoes postsecretory proteolysis of its N terminus to produce a shorter heme-attached PioA (holo-PioAC, where PioAC represents the C terminus of PioA), which can exist both freely in the periplasm and in a complex with PioB. The extended N-terminal peptide controls heme attachment, and its processing is required to produce wild-type levels of holo-PioAC and holo-PioACB complex. It is also conserved in PioA homologs from other phototrophs. The presence of PioAB in these organisms correlate with their ability to perform photoferrotrophy and phototrophic EEU.IMPORTANCE Some anoxygenic phototrophs use soluble iron, insoluble iron minerals (such as rust), or their proxies (poised electrodes) as electron donors for photosynthesis. However, the underlying electron uptake mechanisms are not well established. Here, we show that these phototrophs use a protein complex made of an outer membrane porin and a periplasmic decaheme cytochrome (electron transfer protein) to harvest electrons from both soluble iron and poised electrodes. This complex has two unique characteristics: (i) it lacks an extracellular cytochrome c, and (ii) the periplasmic decaheme cytochrome c undergoes proteolytic cleavage to produce a functional electron transfer protein. These characteristics are conserved in phototrophs harboring homologous proteins.
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Affiliation(s)
- Dinesh Gupta
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Molly C Sutherland
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri, USA
| | | | - J Mark Meacham
- Department of Mechanical Engineering and Materials Science, Washington University in St. Louis, St. Louis, Missouri, USA
- Institute of Materials Science and Engineering, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Robert G Kranz
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Arpita Bose
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri, USA
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Inhibition of Vascular Endothelial Cell Leak Following Escherichia coli Attachment in an Experimental Model of Sepsis. Crit Care Med 2019; 46:e805-e810. [PMID: 29782355 DOI: 10.1097/ccm.0000000000003219] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
OBJECTIVES The vascular endothelium is a major target of sepsis-induced events, and endothelial activation accounts for much of the pathology of sepsis. Urinary tract infections and pneumonia caused by Escherichia coli are among of the most common infections causing sepsis in both community and hospital settings. Currently, there are no approved drugs on the market to treat the underlying pathophysiology of sepsis. The aim of this study is to elucidate the molecular mechanism by which E. coli induces endothelial injury as a result of attachment. DESIGN Laboratory research using a hemodynamic perfusion ex vivo model. SETTING Research Laboratories of Royal College of Surgeons in Ireland and Beaumont Hospital. PATIENTS Ex vivo human vascular endothelial cells. INTERVENTIONS Addition of αVβ3 antagonist, cilengitide. MEASUREMENTS AND MAIN RESULTS Clinical strains of E. coli isolated from patients with sepsis bound to sheared human endothelial cells under static and hemodynamic shear conditions. Binding was dependent on E. coli cell membrane protein outer membrane protein A attaching directly to endothelial cell integrin αVβ3. Attachment resulted in disturbances in endothelial barrier integrity, as determined by loss of tight junction protein staining, permeability changes, and ultimately cell death by apoptosis. Using a low concentration of the αVβ3 antagonist cilengitide or using a strain deficient in outer membrane protein A resulted in a significant reduction in endothelial dysfunction following infection. CONCLUSIONS Inhibition of E. coli binding to endothelial cell αVβ3 by cilengitide prevents endothelial dysfunction and may, therefore, present as a novel early therapeutic for the treatment of sepsis.
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Establishment of a Protein Concentration Gradient in the Outer Membrane Requires Two Diffusion-Limiting Mechanisms. J Bacteriol 2019; 201:JB.00177-19. [PMID: 31209077 DOI: 10.1128/jb.00177-19] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2019] [Accepted: 06/12/2019] [Indexed: 11/20/2022] Open
Abstract
OmpA-like proteins are involved in the stabilization of the outer membrane, resistance to osmotic stress, and pathogenesis. In Caulobacter crescentus, OmpA2 forms a physiologically relevant concentration gradient that forms by an uncharacterized mechanism, in which the gradient orientation depends on the position of the gene locus. This suggests that OmpA2 is synthesized and translocated to the periplasm close to the position of the gene and that the gradient forms by diffusion of the protein from this point. To further understand how the OmpA2 gradient is established, we determined the localization and mobility of the full protein and of its two structural domains. We show that OmpA2 does not diffuse and that both domains are required for gradient formation. The C-terminal domain binds tightly to the cell wall and the immobility of the full protein depends on the binding of this domain to the peptidoglycan; in contrast, the N-terminal membrane β-barrel diffuses slowly. Our results support a model in which once OmpA2 is translocated to the periplasm, the N-terminal membrane β-barrel is required for an initial fast restriction of diffusion until the position of the protein is stabilized by the binding of the C-terminal domain to the cell wall. The implications of these results on outer membrane protein diffusion and organization are discussed.IMPORTANCE Protein concentration gradients play a relevant role in the organization of the bacterial cell. The Caulobacter crescentus protein OmpA2 forms an outer membrane polar concentration gradient. To understand the molecular mechanism that determines the formation of this gradient, we characterized the mobility and localization of the full protein and of its two structural domains an integral outer membrane β-barrel and a periplasmic peptidoglycan binding domain. Each domain has a different role in the formation of the OmpA2 gradient, which occurs in two steps. We also show that the OmpA2 outer membrane β-barrel can diffuse, which is in contrast to what has been reported previously for several integral outer membrane proteins in Escherichia coli, suggesting a different organization of the outer membrane proteins.
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Wang-Lin SX, Balthasar JP. Pharmacokinetic and Pharmacodynamic Considerations for the Use of Monoclonal Antibodies in the Treatment of Bacterial Infections. Antibodies (Basel) 2018; 7:antib7010005. [PMID: 31544858 PMCID: PMC6698815 DOI: 10.3390/antib7010005] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2017] [Revised: 01/01/2018] [Accepted: 01/02/2018] [Indexed: 12/17/2022] Open
Abstract
Antibiotic-resistant bacterial pathogens are increasingly implicated in hospital- and community-acquired infections. Recent advances in monoclonal antibody (mAb) production and engineering have led to renewed interest in the development of antibody-based therapies for treatment of drug-resistant bacterial infections. Currently, there are three antibacterial mAb products approved by the Food and Drug Administration (FDA) and at least nine mAbs are in clinical trials. Antibacterial mAbs are typically developed to kill bacteria or to attenuate bacterial pathological activity through neutralization of bacterial toxins and virulence factors. Antibodies exhibit distinct pharmacological mechanisms from traditional antimicrobials and, hence, cross-resistance between small molecule antimicrobials and antibacterial mAbs is unlikely. Additionally, the long biological half-lives typically found for mAbs may allow convenient dosing and vaccine-like prophylaxis from infection. However, the high affinity of mAbs and the involvement of the host immune system in their pharmacological actions may lead to complex and nonlinear pharmacokinetics and pharmacodynamics. In this review, we summarize the pharmacokinetics and pharmacodynamics of the FDA-approved antibacterial mAbs and those are currently in clinical trials. Challenges in the development of antibacterial mAbs are also discussed.
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Affiliation(s)
- Shun Xin Wang-Lin
- Department of Pharmaceutical Sciences, University at Buffalo, State University of New York, Buffalo, NY 14214, USA.
| | - Joseph P Balthasar
- Department of Pharmaceutical Sciences, University at Buffalo, State University of New York, Buffalo, NY 14214, USA.
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7
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The relationship between capsular type and OmpA of Pasteurella multocida is associated with the outcome of disease. Microb Pathog 2016; 101:68-75. [PMID: 27838388 DOI: 10.1016/j.micpath.2016.11.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Revised: 11/02/2016] [Accepted: 11/08/2016] [Indexed: 02/05/2023]
Abstract
The genes encoding OmpA of Pasteurella multocida recovered from diseased and apparently healthy animals have been characterized. The nucleotide sequence revealed ORFs of 1047-1077 bp encoding proteins of 349-360 amino acids. Domain analysis of OmpA showed signal peptide, N-terminal ompA domain and C-terminal ligand binding domain. The transmembrane topology of OmpA showed short turns at the periplasmic end and longer irregular loops at the extracellular end. The phylogenetic analysis based on OmpA showed affiliation of isolates to 7 groups representing different alleles. The identical segments in OmpA also suggested assortative recombination within classes IV, V and VI of distinct lineages. Principal component analysis separated isolates into groups based on capsular type and PmompA alleles. The alleles belonging to class VI exclusively associated with capsular type A, whereas class I-IV were associated with capsular type B. PmompA alleles in class V were recorded in both serogroups. PmompA6.1, 6.4 were distributed among strains with capsular type A, and PmompA6.2 and 6.3 among capsular type B. Despite internal OmpA variabilty, restrictive and well defined distribution was seen amongst P. multocida. A definitive association of "OmpA-capsular type" was observed with clinical status of animals. A cohort of pasteurellae comprising of OmpA(I-IV)-capB was recovered from diseased animals and OmpA(VI)-capA from healthy subjects. This study concludes that P. multocida with serogroup A and B from healthy and diseased animals represent distinct clusters also differentiated based on their OmpA-types and OmpA-capsular type relationship possibly determine the virulence and disease outcome.
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Naylor KL, Widziolek M, Hunt S, Conolly M, Hicks M, Stafford P, Potempa J, Murdoch C, Douglas CWI, Stafford GP. Role of OmpA2 surface regions of Porphyromonas gingivalis in host-pathogen interactions with oral epithelial cells. Microbiologyopen 2016; 6. [PMID: 27595778 PMCID: PMC5300881 DOI: 10.1002/mbo3.401] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2016] [Revised: 08/03/2016] [Accepted: 08/08/2016] [Indexed: 01/27/2023] Open
Abstract
Outer membrane protein A (OmpA) is a key outer membrane protein found in Gram‐negative bacteria that contributes to several crucial processes in bacterial virulence. In Porphyromonas gingivalis, OmpA is predicted as a heterotrimer of OmpA1 and OmpA2 subunits encoded by adjacent genes. Here we describe the role of OmpA and its individual subunits in the interaction of P. gingivalis with oral cells. Using knockout mutagenesis, we show that OmpA2 plays a significant role in biofilm formation and interaction with human epithelial cells. We used protein structure prediction software to identify extracellular loops of OmpA2, and determined these are involved in interactions with epithelial cells as evidenced by inhibition of adherence and invasion of P. gingivalis by synthetic extracellular loop peptides and the ability of the peptides to mediate interaction of latex beads with human cells. In particular, we observe that OmpA2‐loop 4 plays an important role in the interaction with host cells. These data demonstrate for the first time the important role of P. gingivalis OmpA2 extracellular loops in interaction with epithelial cells, which may help design novel peptide‐based antimicrobial therapies for periodontal disease.
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Affiliation(s)
- Kathryn L Naylor
- School of Clinical Dentistry, University of Sheffield, Sheffield, United Kingdom
| | - Magdalena Widziolek
- Department of Microbiology, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Krakow, Poland
| | - Stuart Hunt
- School of Clinical Dentistry, University of Sheffield, Sheffield, United Kingdom
| | - Mary Conolly
- School of Clinical Dentistry, University of Sheffield, Sheffield, United Kingdom
| | - Matthew Hicks
- School of Clinical Dentistry, University of Sheffield, Sheffield, United Kingdom
| | - Prachi Stafford
- Biomolecular Research Centre, Sheffield Hallam University, City Campus, Sheffield, United Kingdom
| | - Jan Potempa
- Department of Microbiology, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Krakow, Poland.,Department of Oral Immunology and Infectious Diseases, University of Louisville School of Dentistry, Louisville, Kentucky
| | - Craig Murdoch
- School of Clinical Dentistry, University of Sheffield, Sheffield, United Kingdom
| | - C W Ian Douglas
- School of Clinical Dentistry, University of Sheffield, Sheffield, United Kingdom
| | - Graham P Stafford
- School of Clinical Dentistry, University of Sheffield, Sheffield, United Kingdom
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Samaniego-Barrón L, Luna-Castro S, Piña-Vázquez C, Suárez-Güemes F, de la Garza M. Two outer membrane proteins are bovine lactoferrin-binding proteins in Mannheimia haemolytica A1. Vet Res 2016; 47:93. [PMID: 27599994 PMCID: PMC5013584 DOI: 10.1186/s13567-016-0378-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2016] [Accepted: 07/14/2016] [Indexed: 11/10/2022] Open
Abstract
Mannheimia haemolytica is a Gram negative bacterium that is part of the bovine respiratory disease, which causes important economic losses in the livestock industry. In the present work, the interaction between M. haemolytica A1 and bovine lactoferrin (BLf) was studied. This iron-chelating glycoprotein is part of the mammalian innate-immune system and is present in milk and mucosal secretions; Lf is also contained in neutrophils secondary granules, which release this glycoprotein at infection sites. It was evidenced that M. haemolytica was not able to use iron-charged BLf (BholoLf) as a sole iron source; nevertheless, iron-lacked BLf (BapoLf) showed a bactericidal effect against M. haemolytica with MIC of 4.88 ± 1.88 and 7.31 ± 1.62 μM for M. haemolytica strain F (field isolate) and M. haemolytica strain R (reference strain), respectively. Through overlay assays and 2-D electrophoresis, two OMP of 32.9 and 34.2 kDa with estimated IP of 8.18 and 9.35, respectively, were observed to bind both BapoLf and BholoLf; these OMP were identified by Maldi-Tof as OmpA (heat-modifiable OMP) and a membrane protein (porin). These M. haemolytica BLf binding proteins could be interacting in vivo with both forms of BLf depending on the iron state of the bovine.
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Affiliation(s)
- Luisa Samaniego-Barrón
- Departamento de Biología Celular, Centro de Investigación y de Estudios Avanzados del IPN (CINVESTAV-IPN), Avenida Instituto Politécnico Nacional No. 2508, Colonia San Pedro Zacatenco, CP 07360 Ciudad de México, Mexico
| | - Sarahí Luna-Castro
- Facultad de Medicina Veterinaria y Zootecnia Dr. Norberto Treviño Zapata, Universidad Autónoma de Tamaulipas, Carretera a Cd. Mante Km 5, CP 87000 Ciudad Victoria, Tamaulipas Mexico
| | - Carolina Piña-Vázquez
- Departamento de Biología Celular, Centro de Investigación y de Estudios Avanzados del IPN (CINVESTAV-IPN), Avenida Instituto Politécnico Nacional No. 2508, Colonia San Pedro Zacatenco, CP 07360 Ciudad de México, Mexico
| | - Francisco Suárez-Güemes
- Departamento de Microbiología, Facultad de Medicina Veterinaria y Zootecnia, Universidad Nacional Autónoma de México (UNAM), Av. Universidad 3000, Cd. Universitaria, Coyoacán, CP 04510 Ciudad de México, Mexico
| | - Mireya de la Garza
- Departamento de Biología Celular, Centro de Investigación y de Estudios Avanzados del IPN (CINVESTAV-IPN), Avenida Instituto Politécnico Nacional No. 2508, Colonia San Pedro Zacatenco, CP 07360 Ciudad de México, Mexico
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Bosák J, Micenková L, Doležalová M, Šmajs D. Colicins U and Y inhibit growth of Escherichia coli strains via recognition of conserved OmpA extracellular loop 1. Int J Med Microbiol 2016; 306:486-494. [PMID: 27510856 DOI: 10.1016/j.ijmm.2016.07.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Revised: 07/28/2016] [Accepted: 07/31/2016] [Indexed: 01/04/2023] Open
Abstract
Interactions of colicins U and Y with the OmpA (Outer membrane protein A) receptor molecule were studied using site-directed mutagenesis and colicin binding assay. A systematic mutagenesis of the colicin-susceptible OmpA sequence from Escherichia coli (OmpAEC) to the colicin-resistant OmpA sequence from Serratia marcescens (OmpASM) was performed in regions corresponding to extracellular OmpA loops 1-4. Susceptibility to colicins U and Y was significantly affected by the OmpA mutation in loop 1. As with functional analysis, a decrease in binding capacity of His-tagged colicin U was found for recombinant OmpA with a mutated segment in loop 1 compared to control OmpAEC. To verify the importance of the identified amino acid residues in OmpA loop 1, we introduced loop 1 from OmpAEC into OmpASM, which resulted in the substantial increase of susceptibility to colicins U and Y. In addition, colicins U and Y were tested against a panel of 118 bacteriocin non-producing strains of four Escherichia species, including E. coli (39 strains), E. fergusonii (10 strains), E. hermannii (42 strains), and E. vulneris (27 strains). A majority (82%) of E. coli strains was susceptible to colicins U and Y. Interestingly, colicins U and Y also inhibited all of the 30 tested multidrug-resistant E. coli O25b-ST131 isolates. These findings, together with the fact that OmpA loop 1 is important for bacterial virulence and is evolutionary conserved, offer the potential of using colicins U and Y as specific anti-OmpA loop 1 directed antibacterial proteins.
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Affiliation(s)
- Juraj Bosák
- Department of Biology, Faculty of Medicine, Masaryk University, Kamenice 5, Building A6, 625 00 Brno, Czech Republic
| | - Lenka Micenková
- Department of Biology, Faculty of Medicine, Masaryk University, Kamenice 5, Building A6, 625 00 Brno, Czech Republic
| | - Magda Doležalová
- Department of Environment Protection Engineering, Faculty of Technology, Tomas Bata University in Zlín, T. G. Masaryk square 275, Zlín, Czech Republic
| | - David Šmajs
- Department of Biology, Faculty of Medicine, Masaryk University, Kamenice 5, Building A6, 625 00 Brno, Czech Republic.
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Anand A, LeDoyt M, Karanian C, Luthra A, Koszelak-Rosenblum M, Malkowski MG, Puthenveetil R, Vinogradova O, Radolf JD. Bipartite Topology of Treponema pallidum Repeat Proteins C/D and I: OUTER MEMBRANE INSERTION, TRIMERIZATION, AND PORIN FUNCTION REQUIRE A C-TERMINAL β-BARREL DOMAIN. J Biol Chem 2015; 290:12313-31. [PMID: 25805501 PMCID: PMC4424362 DOI: 10.1074/jbc.m114.629188] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2014] [Revised: 03/20/2015] [Indexed: 11/06/2022] Open
Abstract
We previously identified Treponema pallidum repeat proteins TprC/D, TprF, and TprI as candidate outer membrane proteins (OMPs) and subsequently demonstrated that TprC is not only a rare OMP but also forms trimers and has porin activity. We also reported that TprC contains N- and C-terminal domains (TprC(N) and TprC(C)) orthologous to regions in the major outer sheath protein (MOSP(N) and MOSP(C)) of Treponema denticola and that TprC(C) is solely responsible for β-barrel formation, trimerization, and porin function by the full-length protein. Herein, we show that TprI also possesses bipartite architecture, trimeric structure, and porin function and that the MOSP(C)-like domains of native TprC and TprI are surface-exposed in T. pallidum, whereas their MOSP(N)-like domains are tethered within the periplasm. TprF, which does not contain a MOSP(C)-like domain, lacks amphiphilicity and porin activity, adopts an extended inflexible structure, and, in T. pallidum, is tightly bound to the protoplasmic cylinder. By thermal denaturation, the MOSP(N) and MOSP(C)-like domains of TprC and TprI are highly thermostable, endowing the full-length proteins with impressive conformational stability. When expressed in Escherichia coli with PelB signal sequences, TprC and TprI localize to the outer membrane, adopting bipartite topologies, whereas TprF is periplasmic. We propose that the MOSP(N)-like domains enhance the structural integrity of the cell envelope by anchoring the β-barrels within the periplasm. In addition to being bona fide T. pallidum rare outer membrane proteins, TprC/D and TprI represent a new class of dual function, bipartite bacterial OMP.
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Affiliation(s)
| | | | | | | | | | - Michael G Malkowski
- the Hauptman-Woodward Medical Research Institute and Department of Structural Biology, State University of New York, Buffalo, New York 14203, and
| | | | - Olga Vinogradova
- Pharmaceutical Sciences, University of Connecticut, Storrs, Connecticut 06269
| | - Justin D Radolf
- From the Departments of Medicine, Pediatrics, Molecular Biology and Biophysics, Genetics and Genomic Science, and Immunology, University of Connecticut Health Center, Farmington, Connecticut 06030,
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12
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The major outer sheath protein (Msp) of Treponema denticola has a bipartite domain architecture and exists as periplasmic and outer membrane-spanning conformers. J Bacteriol 2013; 195:2060-71. [PMID: 23457251 DOI: 10.1128/jb.00078-13] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The major outer sheath protein (Msp) is a primary virulence determinant in Treponema denticola, as well as the parental ortholog for the Treponema pallidum repeat (Tpr) family in the syphilis spirochete. The Conserved Domain Database (CDD) server revealed that Msp contains two conserved domains, major outer sheath protein(N) (MOSP(N)) and MOSP(C), spanning residues 77 to 286 and 332 to 543, respectively, within the N- and C-terminal regions of the protein. Circular dichroism (CD) spectroscopy, Triton X-114 (TX-114) phase partitioning, and liposome incorporation demonstrated that full-length, recombinant Msp (Msp(Fl)) and a recombinant protein containing MOSP(C), but not MOSP(N), form amphiphilic, β-sheet-rich structures with channel-forming activity. Immunofluorescence analysis of intact T. denticola revealed that only MOSP(C) contains surface-exposed epitopes. Data obtained using proteinase K accessibility, TX-114 phase partitioning, and cell fractionation revealed that Msp exists as distinct OM-integrated and periplasmic trimers. Msp(Fl) folded in Tris buffer contained slightly less β-sheet structure than detergent-folded Msp(Fl); both forms, however, partitioned into the TX-114 detergent-enriched phase. CDD analysis of the nine Tpr paralogs predicted to be outer membrane proteins (OMPs) revealed that seven have an Msp-like bipartite structure; phylogenetic analysis revealed that the MOSP(N) and MOSP(C) domains of Msp are most closely related to those of TprK. Based upon our collective results, we propose a model whereby a newly exported, partially folded intermediate can be either processed for OM insertion by the β-barrel assembly machinery (BAM) or remain periplasmic, ultimately forming a stable, water-soluble trimer. Extrapolated to T. pallidum, our model enables us to explain how individual Tprs can localize to either the periplasmic (e.g., TprK) or OM (e.g., TprC) compartments.
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Ambrosi C, Pompili M, Scribano D, Zagaglia C, Ripa S, Nicoletti M. Outer membrane protein A (OmpA): a new player in shigella flexneri protrusion formation and inter-cellular spreading. PLoS One 2012; 7:e49625. [PMID: 23166731 PMCID: PMC3498225 DOI: 10.1371/journal.pone.0049625] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2012] [Accepted: 10/11/2012] [Indexed: 11/24/2022] Open
Abstract
Outer membrane protein A (OmpA) is a multifaceted predominant outer membrane protein of Escherichia coli and other Enterobacteriaceae whose role in the pathogenesis of various bacterial infections has recently been recognized. Here, the role of OmpA on the virulence of Shigella flexneri has been investigated. An ompA mutant of wild-type S. flexneri 5a strain M90T was constructed (strain HND92) and it was shown to be severely impaired in cell-to-cell spreading since it failed to plaque on HeLa cell monolayers. The lack of OmpA significantly reduced the levels of IcsA while the levels of cell associated and released IcsP-cleaved 95 kDa amino-terminal portion of the mature protein were similar. Nevertheless, the ompA mutant displayed IcsA exposed across the entire bacterial surface. Surprisingly, the ompA mutant produced proper F-actin comet tails, indicating that the aberrant IcsA exposition at bacterial lateral surface did not affect proper activation of actin-nucleating proteins, suggesting that the absence of OmpA likely unmasks mature or cell associated IcsA at bacterial lateral surface. Moreover, the ompA mutant was able to invade and to multiply within HeLa cell monolayers, although internalized bacteria were found to be entrapped within the host cell cytoplasm. We found that the ompA mutant produced significantly less protrusions than the wild-type strain, indicating that this defect could be responsible of its inability to plaque. Although we could not definitely rule out that the ompA mutation might exert pleiotropic effects on other S. flexneri genes, complementation of the ompA mutation with a recombinant plasmid carrying the S. flexneri ompA gene clearly indicated that a functional OmpA protein is required and sufficient for proper IcsA exposition, plaque and protrusion formation. Moreover, an independent ompA mutant was generated. Since we found that both mutants displayed identical virulence profile, these results further supported the findings presented in this study.
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Affiliation(s)
- Cecilia Ambrosi
- Dip. di Scienze Sperimentali e Cliniche, Università “G. D’Annunzio’ di Chieti, Chieti, Italy
| | - Monica Pompili
- Dip. di Sanità Pubblica e Malattie Infettive Università “Sapienza” di Roma, Rome, Italy
| | | | - Carlo Zagaglia
- Dip. di Sanità Pubblica e Malattie Infettive Università “Sapienza” di Roma, Rome, Italy
| | - Sandro Ripa
- Dip. di Biologia Molecolare, Cellulare e Animale Università di Camerino, Camerino (MC), Italy
| | - Mauro Nicoletti
- Dip. di Scienze Sperimentali e Cliniche, Università “G. D’Annunzio’ di Chieti, Chieti, Italy
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Vila J, Soto SM. Salicylate increases the expression of marA and reduces in vitro biofilm formation in uropathogenic Escherichia coli by decreasing type 1 fimbriae expression. Virulence 2012; 3:280-5. [PMID: 22546909 DOI: 10.4161/viru.19205] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Escherichia coli is one of the most frequent bacteria implicated in biofilm formation, which is a dynamic process whose first step consists in bacteria adhesion to surfaces through type 1 fimbriae. Salicylate induces a number of morphological and physiological alterations in bacteria including the activation of the transcriptional regulator MarA. In this report the effects of salicylate on biofilm formation and their relationship with MarA were studied. An inverse relationship was observed between in vitro biofilm formation and salicylate concentration added to the culture medium. Salicylate increases the expression of marA and decreases the expression of fimA and fimB genes in the wild-type strain. In addition, the fimA and fimB expression was decreased in a MarR mutant in which marA was also overexpressed. In conclusion, the expression of type 1 fimbriae in presence of salicylate may be regulated by the level of marA expression through fimB regulator, albeit through neither the ompX nor the tolC genes.
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Affiliation(s)
- Jordi Vila
- Barcelona Centre for International Health Research, CRESIB, Hospital Clinic-University of Barcelona, Barcelona, Spain
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15
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TprC/D (Tp0117/131), a trimeric, pore-forming rare outer membrane protein of Treponema pallidum, has a bipartite domain structure. J Bacteriol 2012; 194:2321-33. [PMID: 22389487 DOI: 10.1128/jb.00101-12] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Identification of Treponema pallidum rare outer membrane proteins (OMPs) has been a longstanding objective of syphilis researchers. We recently developed a consensus computational framework that employs a battery of cellular localization and topological prediction tools to generate ranked clusters of candidate rare OMPs (D. L. Cox et al., Infect. Immun. 78:5178-5194, 2010). TP0117/TP0131 (TprC/D), a member of the T. pallidum repeat (Tpr) family, was a highly ranked candidate. Circular dichroism, heat modifiability by SDS-PAGE, Triton X-114 phase partitioning, and liposome incorporation confirmed that full-length, recombinant TprC (TprC(Fl)) forms a β-barrel capable of integrating into lipid bilayers. Moreover, TprC(Fl) increased efflux of terbium-dipicolinic acid complex from large unilamellar vesicles and migrated as a trimer by blue-native PAGE. We found that in T. pallidum, TprC is heat modifiable, trimeric, expressed in low abundance, and, based on proteinase K accessibility and opsonophagocytosis assays, surface exposed. From these collective data, we conclude that TprC is a bona fide rare OMP as well as a functional ortholog of Escherichia coli OmpF. We also discovered that TprC has a bipartite architecture consisting of a soluble N-terminal portion (TprC(N)), presumably periplasmic and bound directly or indirectly to peptidoglycan, and a C-terminal β-barrel (TprC(C)). Syphilitic rabbits generate antibodies exclusively against TprC(C), while secondary syphilis patients fail to mount a detectable antibody response against either domain. The syphilis spirochete appears to have resolved a fundamental dilemma arising from its extracellular lifestyle, namely, how to enhance OM permeability without increasing its vulnerability to the antibody-mediated defenses of its natural human host.
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Hounsome JDA, Baillie S, Noofeli M, Riboldi-Tunnicliffe A, Burchmore RJS, Isaacs NW, Davies RL. Outer membrane protein A of bovine and ovine isolates of Mannheimia haemolytica is surface exposed and contains host species-specific epitopes. Infect Immun 2011; 79:4332-41. [PMID: 21896777 PMCID: PMC3257919 DOI: 10.1128/iai.05469-11] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2011] [Revised: 06/23/2011] [Accepted: 08/08/2011] [Indexed: 01/21/2023] Open
Abstract
Mannheimia haemolytica is the etiological agent of pneumonic pasteurellosis of cattle and sheep; two different OmpA subclasses, OmpA1 and OmpA2, are associated with bovine and ovine isolates, respectively. These proteins differ at the distal ends of four external loops, are involved in adherence, and are likely to play important roles in host adaptation. M. haemolytica is surrounded by a polysaccharide capsule, and the degree of OmpA surface exposure is unknown. To investigate surface exposure and immune specificity of OmpA among bovine and ovine M. haemolytica isolates, recombinant proteins representing the transmembrane domain of OmpA from a bovine serotype A1 isolate (rOmpA1) and an ovine serotype A2 isolate (rOmpA2) were overexpressed, purified, and used to generate anti-rOmpA1 and anti-rOmpA2 antibodies, respectively. Immunogold electron microscopy and immunofluorescence techniques demonstrated that OmpA1 and OmpA2 are surface exposed, and are not masked by the polysaccharide capsule, in a selection of M. haemolytica isolates of various serotypes and grown under different growth conditions. To explore epitope specificity, anti-rOmpA1 and anti-rOmpA2 antibodies were cross-absorbed with the heterologous isolate to remove cross-reacting antibodies. These cross-absorbed antibodies were highly specific and recognized only the OmpA protein of the homologous isolate in Western blot assays. A wider examination of the binding specificities of these antibodies for M. haemolytica isolates representing different OmpA subclasses revealed that cross-absorbed anti-rOmpA1 antibodies recognized OmpA1-type proteins but not OmpA2-type proteins; conversely, cross-absorbed anti-rOmpA2 antibodies recognized OmpA2-type proteins but not OmpA1-type proteins. Our results demonstrate that OmpA1 and OmpA2 are surface exposed and could potentially bind to different receptors in cattle and sheep.
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Affiliation(s)
- Jonathan D. A. Hounsome
- Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Susan Baillie
- Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Mojtaba Noofeli
- Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Alan Riboldi-Tunnicliffe
- School of Chemistry, College of Science and Engineering, University of Glasgow, Glasgow, United Kingdom
| | - Richard J. S. Burchmore
- Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Neil W. Isaacs
- School of Chemistry, College of Science and Engineering, University of Glasgow, Glasgow, United Kingdom
| | - Robert L. Davies
- Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
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Cowles CE, Li Y, Semmelhack MF, Cristea IM, Silhavy TJ. The free and bound forms of Lpp occupy distinct subcellular locations in Escherichia coli. Mol Microbiol 2011; 79:1168-81. [PMID: 21219470 DOI: 10.1111/j.1365-2958.2011.07539.x] [Citation(s) in RCA: 99] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The lipoprotein Lpp is the most numerically abundant protein in Escherichia coli, has been investigated for over 40 years, and has served as the paradigmatic bacterial lipoprotein since its initial discovery. It exists in two distinct forms: a 'bound-form', which is covalently bound to the cell's peptidoglycan layer, and a 'free-form', which is not. Although it is known that the carboxyl-terminus of bound-form Lpp is located in the periplasm, the precise location of free-form Lpp has never been determined. For decades, it has been widely assumed that free-form Lpp is associated with bound-form. In this work, we show that the free and bound forms of Lpp are not largely associated with each other, but are found in distinct subcellular locations. Our results indicate that free-form Lpp spans the outer membrane and is surface-exposed, whereas bound-form Lpp resides in the periplasm. Thus, Lpp represents a novel example of a single lipoprotein that is able to occupy distinct subcellular locations, and challenges models in which the free and bound forms of Lpp are assumed to be associated with each other.
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Affiliation(s)
- Charles E Cowles
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA
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18
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Mittal R, Krishnan S, Gonzalez-Gomez I, Prasadarao NV. Deciphering the roles of outer membrane protein A extracellular loops in the pathogenesis of Escherichia coli K1 meningitis. J Biol Chem 2011; 286:2183-93. [PMID: 21071448 PMCID: PMC3023514 DOI: 10.1074/jbc.m110.178236] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2010] [Revised: 10/05/2010] [Indexed: 11/06/2022] Open
Abstract
Outer membrane protein A (OmpA) has been implicated as an important virulence factor in several gram-negative bacterial infections such as Escherichia coli K1, a leading cause of neonatal meningitis associated with significant mortality and morbidity. In this study, we generated E. coli K1 mutants that express OmpA in which three or four amino acids from various extracellular loops were changed to alanines, and we examined their ability to survive in several immune cells. We observed that loop regions 1 and 2 play an important role in the survival of E. coli K1 inside neutrophils and dendritic cells, and loop regions 1 and 3 are needed for survival in macrophages. Concomitantly, E. coli K1 mutants expressing loop 1 and 2 mutations were unable to cause meningitis in a newborn mouse model. Of note, mutations in loop 4 of OmpA enhance the severity of the pathogenesis by allowing the pathogen to survive better in circulation and to produce high bacteremia levels. These results demonstrate, for the first time, the roles played by different regions of extracellular loops of OmpA of E. coli K1 in the pathogenesis of meningitis and may help in designing effective preventive strategies against this deadly disease.
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Affiliation(s)
- Rahul Mittal
- From the Division of Infectious Diseases, Department of Pediatrics, and
| | | | | | - Nemani V. Prasadarao
- From the Division of Infectious Diseases, Department of Pediatrics, and
- Surgery
- Saban Research Institute, Childrens Hospital Los Angeles and Keck School of Medicine, University of Southern California, Los Angeles, California 90027
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19
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Zhang DF, Li H, Lin XM, Wang SY, Peng XX. Characterization of Outer Membrane Proteins of Escherichia Coli in Response to Phenol Stress. Curr Microbiol 2010; 62:777-83. [DOI: 10.1007/s00284-010-9786-z] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2010] [Accepted: 09/22/2010] [Indexed: 01/22/2023]
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20
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STIMSON WH. Characterisation of anti- Escherichia coli Monoclonal Antibodies for Use in Diagnostic Assays. FOOD AGR IMMUNOL 2010. [DOI: 10.1080/09540109999924] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022] Open
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21
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Abu Khweek A, Fetherston JD, Perry RD. Analysis of HmsH and its role in plague biofilm formation. MICROBIOLOGY-SGM 2010; 156:1424-1438. [PMID: 20093287 DOI: 10.1099/mic.0.036640-0] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The Yersinia pestis Hms(+) phenotype is a manifestation of biofilm formation that causes adsorption of Congo red and haemin at 26 degrees C but not at 37 degrees C. This phenotype is required for blockage of the proventricular valve of the oriental rat flea and plays a role in transmission of bubonic plague from fleas to mammals. Genes responsible for this phenotype are located in three separate operons, hmsHFRS, hmsT and hmsP. HmsH and HmsF are outer membrane (OM) proteins, while the other four Hms proteins are located in the inner membrane. According to the Hidden Markov Method-based predictor, HmsH has a large N terminus in the periplasm, a beta-barrel structure with 16 beta-strands that traverse the OM, eight surface-exposed loops, and seven short turns connecting the beta-strands on the periplasmic side. Here, we demonstrate that HmsH is a heat-modifiable protein, a characteristic of other beta-barrel proteins, thereby supporting the bioinformatics analysis. Alanine scanning mutagenesis was used to identify conserved amino acids in the HmsH-like family that are critical for the function of HmsH in biofilm formation. Of 23 conserved amino acids mutated, four residues affected HmsH function and three likely caused protein instability. We used formaldehyde cross-linking to demonstrate that HmsH interacts with HmsF but not with HmsR, HmsS, HmsT or HmsP. Loss-of-function HmsH variants with single alanine substitutions retained their beta-structure and interaction with HmsF. Finally, using a polar hmsH : : mini-kan mutant, we demonstrated that biofilm development is not important for the pathogenesis of bubonic or pneumonic plague in mice.
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Affiliation(s)
- Arwa Abu Khweek
- Department of Microbiology, Immunology, and Molecular Genetics, University of Kentucky, 800 Rose St., Lexington, KY, USA
| | - Jacqueline D Fetherston
- Department of Microbiology, Immunology, and Molecular Genetics, University of Kentucky, 800 Rose St., Lexington, KY, USA
| | - Robert D Perry
- Department of Microbiology, Immunology, and Molecular Genetics, University of Kentucky, 800 Rose St., Lexington, KY, USA
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22
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Identification of Mannheimia haemolytica adhesins involved in binding to bovine bronchial epithelial cells. Infect Immun 2008; 77:446-55. [PMID: 18981250 DOI: 10.1128/iai.00312-08] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Mannheimia haemolytica, a commensal organism of the upper respiratory tract in cattle, is the principal bacterial pathogen associated with the bovine respiratory disease complex. Adherence to the respiratory mucosa is a crucial event in its pathogenesis. However, the bacterial components that contribute to this process are not fully characterized. In this study, we demonstrated that M. haemolytica adhered to bovine bronchial epithelial cells (BBEC) in vitro and that adherence was inhibited by anti-M. haemolytica antibody. Western blot analysis of M. haemolytica proteins that bind to BBEC showed a dominant protein band with an apparent molecular mass of approximately 30 kDa. Peptide sequences for the 30-kDa BBEC-binding proteins, as determined by liquid chromatography-tandem mass spectrometry, matched two M. haemolytica surface proteins: heat-modifiable outer membrane protein A (OmpA) and lipoprotein 1 (Lpp1). Western blotting showed that the 30-kDa protein band is recognized by both anti-M. haemolytica OmpA and anti-Lpp1 antibodies. Furthermore, incubation with anti-OmpA and anti-Lpp1 antibodies significantly inhibited M. haemolytica binding to BBEC monolayers. In summary, these results suggest that OmpA and Lpp1 contribute to adherence of M. haemolytica to bovine respiratory epithelial cells.
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24
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Mendu DR, Dasari VR, Cai M, Kim KS. Protein folding intermediates of invasin protein IbeA from Escherichia coli. FEBS J 2007; 275:458-69. [PMID: 18167139 DOI: 10.1111/j.1742-4658.2007.06213.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
IbeA of Escherichia coli K1 was cloned, expressed and purified as a His(6)-tag fusion protein. The purified fusion protein inhibited E. coli K1 invasion of human brain microvascular endothelial cells and was heat-modifiable. The structural and functional aspects, along with equilibrium unfolding of IbeA, were studied in solution. The far-UV CD spectrum of IbeA at pH 7.0 has a strong negative peak at 215 nm, indicating the existence of beta-sheet-like structure. The acidic unfolding curve of IbeA at pH 2.0 shows the existence of a partially unfolded molecule (molten globule-like structure) with beta-sheet-like structure and displays strong 8-anilino-2-naphthyl sulfonic acid (ANS) binding. The pH dependent intrinsic fluorescence of IbeA was biphasic. At pH 2.0, IbeA exists in a partially unfolded state with characteristics of a molten globule-like state, and the protein is in extended beta-sheet conformation and exhibits strong ANS binding. Guanidine hydrochloride denaturation of IbeA in the molten globule-like state is noncooperative, contrary to the cooperativity seen with the native protein, suggesting the presence of two domains (possibly) in the molecular structure of IbeA, with differential unfolding stabilities. Furthermore, tryptophan quenching studies suggested the exposure of aromatic residues to solvent in this state. Acid denatured unfolding of IbeA monitored by far-UV CD is non-cooperative with two transitions at pH 3.0-1.5 and 1.5-0.5. At lower pH, IbeA unfolds to the acid-unfolded state, and a further decrease in pH to 2.0 drives the protein to the A state. The presence of 0.5 m KCl in the solvent composition directs the transition to the A state by bypassing the acid-unfolded state. Additional guanidine hydrochloride induced conformational changes in IbeA from the native to the A-state, as monitored by near- and far-UV CD and ANS-fluorescence.
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Affiliation(s)
- Damodara R Mendu
- Department of Pediatrics, Division of Infectious Diseases, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
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25
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Serino L, Nesta B, Leuzzi R, Fontana MR, Monaci E, Mocca BT, Cartocci E, Masignani V, Jerse AE, Rappuoli R, Pizza M. Identification of a new OmpA-like protein in Neisseria gonorrhoeae involved in the binding to human epithelial cells and in vivo colonization. Mol Microbiol 2007; 64:1391-403. [PMID: 17542928 DOI: 10.1111/j.1365-2958.2007.05745.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Outer membrane protein As (OmpAs) are highly conserved proteins within the Enterobacteriaceae family. OmpA contributes to the maintenance of structural membrane integrity and invasion into mammalian cells. In Escherichia coli K1 OmpA also contributes to serum resistance and is involved in the virulence of the bacterium. Here we describe the identification of an OmpA-like protein in Neisseria gonorrhoeae (Ng-OmpA). We show that the gonococcal OmpA-like protein, similarly to E. coli OmpA, plays a significant role in the adhesion and invasion into human cervical carcinoma and endometrial cells and is required for entry into macrophages and intracellular survival. Furthermore, the isogenic knockout ompA mutant demonstrates reduced recovery in a mouse model of infection when compared with the wild-type strain, suggesting that Ng-OmpA plays an important role in the in vivo colonization. All together, these data suggest that the newly identified surface exposed protein Ng-OmpA represents a novel virulence factor of gonococcus.
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Affiliation(s)
- Laura Serino
- Research Centre, Novartis Vaccines, Via Fiorentina, 1, 53100 Siena, Italy.
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Collin S, Guilvout I, Chami M, Pugsley AP. YaeT-independent multimerization and outer membrane association of secretin PulD. Mol Microbiol 2007; 64:1350-7. [PMID: 17542925 DOI: 10.1111/j.1365-2958.2007.05743.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Previous studies demonstrated that targeting of the dodecameric secretin PulD to the Escherichia coli outer membrane is strictly dependent on the chaperone-like pilotin PulS. Here, we report that PulD multimerization and membrane association in strains producing PulS were unaffected when the levels of the essential outer membrane assembly factor YaeT(Omp85) were reduced by controlled expression of a paraBAD-yaeT transcriptional fusion. This behaviour contrasted markedly to that of the trimeric porin LamB, which remained monomeric under these conditions. Furthermore, resistance to extraction by the detergent Sarkosyl and by urea, and susceptibility to trypsin digestion all suggested that PulD localized to the outer membrane in YaeT-depleted cells. We conclude that, unlike classical beta-barrel outer membrane proteins such as LamB, multimerization of PulD is largely YaeT-independent.
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Affiliation(s)
- Séverine Collin
- Molecular Genetics Unit and CNRS URA2172, Institut Pasteur, 25, rue du Dr Roux, 75724 Paris Cedex 15, France
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27
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Singh R, Shasany AK, Aggarwal A, Sinha S, Sisodia BS, Khanuja SPS, Misra R. Low molecular weight proteins of outer membrane of Salmonella typhimurium are immunogenic in Salmonella induced reactive arthritis revealed by proteomics. Clin Exp Immunol 2007; 148:486-93. [PMID: 17376200 PMCID: PMC1941924 DOI: 10.1111/j.1365-2249.2007.03362.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
In patients with reactive arthritis (ReA)/undifferentiated spondyloarthropathy (uSpA), synovial fluid mononuclear cells (SFMC) show proliferation to bacterial antigens that trigger ReA, i.e. Chlamydia, Yersinia, Campylobactor, Shigella and Salmonella species. We have shown previously that SFMC proliferate significantly to outer membrane proteins of S typhimurium in Salmonella induced ReA. In the present study we characterized the immunoreactive fractions of outer membrane protein (Omp) of S typhimurium in Salmonella induced ReA. Omp of Salmonella was isolated and fractionated by continuous elution sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) using Prep-Cell into eight Omp fractions based on molecular weight. Twenty-three patients with ReA were screened for the bacterial trigger using the SFMC proliferative response to crude lysates of Y enterocolitica, S flexneri, C jejuni and S typhimurium using thymidine uptake assay. SFMC from patients with salmonella induced ReA were tested against eight fractions. Seven of 23 patients with ReA had S typhimurium-induced ReA. Of these seven patients, five patients SFMC had a significant stimulation index (SI) against < 22, 22-26, 25-35 and 28-40 kDa fractions of Omp. These fractions were analysed by SDS-PAGE and matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry, which revealed 10 proteins. These proteins were 37 kDa OmpA, 33 kDa TsX, 28 kDa putative Omp, 28 kDa Vac J, 39 kDa OmpD, 18 kDa OmpX, 23 kDa OmpW, 43 kDa OmpS1 and 19 kDa peptidoglycan-associated lipoprotein. In conclusion, for the first time we have identified some low molecular weight proteins in the Omps of Salmonella which are T cells immunoreactive in patients with salmonella induced ReA/uSpA.
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Affiliation(s)
- R Singh
- Department of Immunology, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, India
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28
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Stegmeier JF, Glück A, Sukumaran S, Mäntele W, Andersen C. Characterisation of YtfM, a second member of the Omp85 family in Escherichia coli. Biol Chem 2007; 388:37-46. [PMID: 17214547 DOI: 10.1515/bc.2007.004] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Omp85 proteins form a ubiquitous protein family, members of which are found in all Gram-negative bacteria. Omp85 of Neisseria meningitidis and YaeT of Escherichia coli are shown to be essential for outer membrane biogenesis. Interestingly, there exists a homologue to YaeT in E. coli and many proteobacteria, denoted YtfM, the function of which has not been described yet. Like YaeT, YtfM is predicted to consist of an amino-terminal periplasmic domain and a membrane-located carboxy-terminal domain. In this study, we present a first characterisation of YtfM by comparison to YaeT concerning structural, biochemical and electrophysiological properties. Furthermore, a knockout strain revealed that ytfM is a non-essential gene and lack of the protein had no effect on outer membrane composition and integrity. The only observable phenotype was strongly reduced growth, indicating an important role of YtfM in vivo.
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Affiliation(s)
- Johannes F Stegmeier
- Lehrstuhl für Biotechnologie, Biozentrum der Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
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Orme R, Douglas CWI, Rimmer S, Webb M. Proteomic analysis of Escherichia coli biofilms reveals the overexpression of the outer membrane protein OmpA. Proteomics 2006; 6:4269-77. [PMID: 16888722 DOI: 10.1002/pmic.200600193] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Bacterial colonisation and biofilm formation on the surface of urinary catheters is a common cause of nosocomial infection, and as such is a major impediment to their long-term use. Understanding the mechanisms of biofilm formation on urinary catheters is critical to their control and will aid the future development of materials used in their manufacture. In this report we have used proteomic analysis coupled with immunoassays to show that the major outer membrane protein (OmpA) of Escherichia coli is overexpressed during biofilm formation. A series of synthetic hydrogels being developed for potential use as catheter coatings were used as the substrata and OmpA expression was increased in biofilms on all these surfaces, as well as being a feature of both a laboratory and a clinical strain of E. coli. Up-regulation of OmpA may, therefore, be a common feature of E. coli biofilms. These findings present OmpA as a potential target for biofilm inhibition and may contribute to the rational design of biofilm inhibiting hydrogel coatings for urinary catheters.
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Affiliation(s)
- Rowan Orme
- University of Manchester, Faculty of Medicine and Human Health, Centre for Molecular Medicine, Department of Medical Genetics, Manchester, UK
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Power ML, Ferrari BC, Littlefield-Wyer J, Gordon DM, Slade MB, Veal DA. A naturally occurring novel allele of Escherichia coli outer membrane protein A reduces sensitivity to bacteriophage. Appl Environ Microbiol 2006; 72:7930-2. [PMID: 16980421 PMCID: PMC1694255 DOI: 10.1128/aem.01040-06] [Citation(s) in RCA: 23] [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
A novel Escherichia coli outer membrane protein A (OmpA) was discovered through a proteomic investigation of cell surface proteins. DNA polymorphisms were localized to regions encoding the protein's surface-exposed loops which are known phage receptor sites. Bacteriophage sensitivity testing indicated an association between bacteriophage resistance and isolates having the novel ompA allele.
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Affiliation(s)
- Michelle L Power
- Department of Biological Sciences, Macquarie University, North Ryde, Sydney, NSW 2109, Australia.
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31
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Stegmeier JF, Andersen C. Characterization of Pores Formed by YaeT (Omp85) from Escherichia coli. ACTA ACUST UNITED AC 2006; 140:275-83. [PMID: 16829683 DOI: 10.1093/jb/mvj147] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Proteins of the Omp85 family play a major role in the biogenesis of the bacterial outer membrane, since they were shown to mediate insertion of outer membrane proteins. The Escherichia coli Omp85 homologue YaeT is essential for viability, but its exact mode of action is not yet elucidated. We could show that YaeT is composed of two distinct domains, an amino-terminal periplasmic and a carboxy-terminal membrane domain. The full length YaeT and the isolated membrane domain induce pores when reconstituted in planar lipid membranes. The pores exhibit a certain variability of conductance indicating a flexible structure, which could be an essential property of a lateral opening channel releasing proteins into the bacterial outer membrane. We could further show that the periplasmic domain proves to be essential for in vivo function of YaeT.
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Affiliation(s)
- Johannes F Stegmeier
- Universität Würzburg, Lehrstuhl für Biotechnologie, Biozentrum der Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
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Choi CH, Lee EY, Lee YC, Park TI, Kim HJ, Hyun SH, Kim SA, Lee SK, Lee JC. Outer membrane protein 38 of Acinetobacter baumannii localizes to the mitochondria and induces apoptosis of epithelial cells. Cell Microbiol 2005; 7:1127-38. [PMID: 16008580 DOI: 10.1111/j.1462-5822.2005.00538.x] [Citation(s) in RCA: 217] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Acinetobacter baumannii is an important opportunistic pathogen responsible for nosocomial infection. Despite considerable clinical and epidemiological data regarding the role of A. baumannii in nosocomial infection, the specific virulence factor or pathogenic mechanism of this organism has yet to be elucidated. This study investigated the molecular mechanism of apoptosis on the infection of human laryngeal epithelial HEp-2 cells with A. baumannii and examined the contribution of outer membrane protein 38 (Omp38) on the ability of A. baumannii to induce apoptosis of epithelial cells. A. baumannii induced apoptosis of HEp-2 cells through cell surface death receptors and mitochondrial disintegration. The Omp38-deficient mutant was not as able to induce apoptosis as the wild-type A. baumannii strain. Purified Omp38 entered the cells and was localized to the mitochondria, which led to a release of proapoptotic molecules such as cytochrome c and apoptosis-inducing factor (AIF). The activation of caspase-3, which is activated by caspase-9, degraded DNA approximately 180 bp in size, which resulted in the appearance of a characteristic DNA ladder. AIF degraded chromosomal DNA approximately 50 kb in size, which resulted in large-scale DNA fragmentation. These results demonstrate that Omp38 may act as a potential virulence factor to induce apoptosis of epithelial cells in the early stage of A. baumannii infection.
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Affiliation(s)
- Chul Hee Choi
- Department of Microbiology, Kyungpook National University School of Medicine, Daegu 700-422, Korea
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Nandi B, Nandy RK, Sarkar A, Ghose AC. Structural features, properties and regulation of the outer-membrane protein W (OmpW) of Vibrio cholerae. Microbiology (Reading) 2005; 151:2975-2986. [PMID: 16151208 DOI: 10.1099/mic.0.27995-0] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
The outer-membrane protein OmpW ofVibrio choleraewas studied with respect to its structure, functional properties and regulation of expression. On SDS-PAGE, the membrane-associated form of OmpW protein (solubilized by either 0·1 % or 2 % SDS at 25 °C) migrated as a monomer of 19 kDa that changed to 21 kDa on boiling. The protein was hyperexpressed inEscherichia coliin the histidine-tagged form and the purified His6-OmpW (heated or unheated) migrated as a 23 kDa protein on SDS-PAGE. Circular dichroism and Fourier-transform infrared spectroscopic analyses of the recombinant protein showed the presence ofβ-structures (∼40 %) with minor amounts (8–15 %) ofα-helix. These results were consistent with those obtained by computational analysis of the sequence data of the protein using the secondary structure prediction program Jnet. The recombinant protein did not exhibit any porin-like property in a liposome-swelling assay. An antiserum to the purified protein induced a moderate level (66·6 % and 33·3 % at 1 : 50 and 1 : 100 dilutions, respectively) of passive protection against live vibrio challenge in a suckling mouse model. OmpW-deficient mutants ofV. choleraestrains were generated by insertion mutagenesis. In a competitive assay in mice, the intestinal colonization activities of these mutants were found to be either only marginally diminished (for O1 strains) or 10-fold less (for an O139 strain) as compared to those of the corresponding wild-type strains. The OmpW protein was expressedin vivoas well asin vitroin liquid culture medium devoid of glucose. Interestingly, the glucose-dependent regulation of OmpW expression was less prominent in a ToxR−mutant ofV. cholerae. Further, the expression of OmpW protein was found to be dependent onin vitrocultural conditions such as temperature, salinity, and availability of nutrients or oxygen. These results suggest that the modulation of OmpW expression by environmental factors may be linked to the adaptive response of the organism under stress conditions.
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Affiliation(s)
- Bisweswar Nandi
- Department of Microbiology, Bose Institute, Kolkata-700 054, India
| | - Ranjan K Nandy
- National Institute of Cholera and Enteric Diseases, P33 CIT Road, Scheme XM, Kolkata-700 010, India
| | - Amit Sarkar
- Department of Microbiology, Bose Institute, Kolkata-700 054, India
| | - Asoke C Ghose
- National Institute of Cholera and Enteric Diseases, P33 CIT Road, Scheme XM, Kolkata-700 010, India
- Department of Microbiology, Bose Institute, Kolkata-700 054, India
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Hiller M, Krabben L, Vinothkumar KR, Castellani F, van Rossum BJ, Kühlbrandt W, Oschkinat H. Solid-State Magic-Angle Spinning NMR of Outer-Membrane Protein G from Escherichia coli. Chembiochem 2005; 6:1679-84. [PMID: 16138308 DOI: 10.1002/cbic.200500132] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Uniformly 13C-,15N-labelled outer-membrane protein G (OmpG) from Escherichia coli was expressed for structural studies by solid-state magic-angle spinning (MAS) NMR. Inclusion bodies of the recombinant, labelled protein were purified under denaturing conditions and refolded in detergent. OmpG was reconstituted into lipid bilayers and several milligrams of two-dimensional crystals were obtained. Solid-state MAS NMR spectra showed signals with an apparent line width of 80-120 Hz (including homonuclear scalar couplings). Signal patterns for several amino acids, including threonines, prolines and serines were resolved and identified in 2D proton-driven spin-diffusion (PDSD) spectra.
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Affiliation(s)
- Matthias Hiller
- Forschungsinstitut für Molekulare Pharmakologie, Robert-Rössle-Strasse 10, 13125 Berlin, Germany
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Hari-Dass R, Shah C, Meyer DJ, Raynes JG. Serum amyloid A protein binds to outer membrane protein A of gram-negative bacteria. J Biol Chem 2005; 280:18562-7. [PMID: 15705572 DOI: 10.1074/jbc.m500490200] [Citation(s) in RCA: 98] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Serum amyloid A (SAA) is the major acute phase protein in man and most mammals. We observed SAA binding to a surprisingly large number of Gram-negative bacteria, including Escherichia coli, Salmonella typhimurium, Shigella flexneri, Klebsiella pneumoniae, Vibrio cholerae, and Pseudomonas aeruginosa. The binding was found to be high affinity and rapid. Importantly, this binding was not inhibited by high density lipoprotein with which SAA is normally complexed in serum. Binding was also observed when bacteria were offered serum containing SAA. Ligand blots following SDS-PAGE or two-dimensional gels revealed two major ligands of 29 and 35 kDa that bound SAA when probing with radiolabeled SAA or SAA and monoclonal anti-SAA. Following fractionation the ligand was found in the outer membrane fraction of E. coli and was identified by matrix-assisted laser desorption ionization time-of-flight mass spectrometry to be outer membrane protein A (OmpA). OmpA-deficient E. coli did not bind SAA, and following purification of OmpA the protein retained binding activity. The ligands on other bacteria were likely to be homologues of OmpA because wild type, but not OprF-deficient, P. aeruginosa bound SAA.
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Affiliation(s)
- Ranjeeta Hari-Dass
- Immunology Unit, Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, United Kingdom
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Davies RL, Lee I. Sequence diversity and molecular evolution of the heat-modifiable outer membrane protein gene (ompA) of Mannheimia(Pasteurella) haemolytica, Mannheimia glucosida, and Pasteurella trehalosi. J Bacteriol 2004; 186:5741-52. [PMID: 15317779 PMCID: PMC516818 DOI: 10.1128/jb.186.17.5741-5752.2004] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The OmpA (or heat-modifiable) protein is a major structural component of the outer membranes of gram-negative bacteria. The protein contains eight membrane-traversing beta-strands and four surface-exposed loops. The genetic diversity and molecular evolution of OmpA were investigated in 31 Mannheimia (Pasteurella) haemolytica, 6 Mannheimia glucosida, and 4 Pasteurella trehalosi strains by comparative nucleotide sequence analysis. The OmpA proteins of M. haemolytica and M. glucosida contain four hypervariable domains located at the distal ends of the surface-exposed loops. The hypervariable domains of OmpA proteins from bovine and ovine M. haemolytica isolates are very different but are highly conserved among strains from each of these two host species. Fourteen different alleles representing four distinct phylogenetic classes, classes I to IV, were identified in M. haemolytica and M. glucosida. Class I, II, and IV alleles were associated with bovine M. haemolytica, ovine M. haemolytica, and M. glucosida strains, respectively, whereas class III alleles were present in certain M. haemolytica and M. glucosida isolates. Class I and II alleles were associated with divergent lineages of bovine and ovine M. haemolytica strains, respectively, indicating a history of horizontal DNA transfer and assortative (entire gene) recombination. Class III alleles have mosaic structures and were derived by horizontal DNA transfer and intragenic recombination. Our findings suggest that OmpA is under strong selective pressure from the host species and that it plays an important role in host adaptation. It is proposed that the OmpA protein of M. haemolytica acts as a ligand and is involved in binding to specific host cell receptor molecules in cattle and sheep. P. trehalosi expresses two OmpA homologs that are encoded by different tandemly arranged ompA genes. The P. trehalosi ompA genes are highly diverged from those of M. haemolytica and M. glucosida, and evidence is presented to suggest that at least one of these genes was acquired by horizontal DNA transfer.
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Affiliation(s)
- Robert L Davies
- Division of Infection and Immunity, Institute of Biomedical and Life Sciences, Joseph Black Building, University of Glasgow, Glasgow G12 8QQ, United Kingdom.
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37
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Abstract
Mycobacteria protect themselves with an outer lipid bilayer, which is the thickest biological membrane hitherto known and has an exceptionally low permeability rendering mycobacteria intrinsically resistant to many antibiotics. Pore proteins spanning the outer membrane mediate the diffusion of hydrophilic nutrients. Mycobacterium tuberculosis possesses at least two porins in addition to the low activity channel protein OmpATb. OmpATb is essential for adaptation of M. tuberculosis to low pH and survival in macrophages and mice. The channel activity of OmpATb is likely to play a major role in the defence of M. tuberculosis against acidification within the phagosome of macrophages. MspA is the main porin of Mycobacterium smegmatis. It forms a tetrameric complex with a single central pore of 10 nm length and a cone-like structure. This structure differs clearly from that of the trimeric porins of Gram-negative bacteria, which form one 4 nm long pore per monomer. The 45-fold lower number of porins compared to Gram-negative bacteria and the exceptional length of the pores are two major determinants of the low permeability of the outer membrane of M. smegmatis for hydrophilic solutes. The importance of the synergism between slow transport through the porins and drug efflux or inactivation for the development of drugs against M. tuberculosis is discussed.
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Affiliation(s)
- Michael Niederweis
- Lehrstuhl für Mikrobiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Staudtstr. 5, 91058 Erlangen, Germany.
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38
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The C-terminal domain of Salmonella enterica serovar typhimurium OmpA is an immunodominant antigen in mice but appears to be only partially exposed on the bacterial cell surface. Infect Immun 2003. [PMID: 12819080 DOI: 10.1128/iai.71.7.3937–3946.2003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
We examined the way the major outer membrane protein OmpA of Salmonella enterica serovar Typhimurium is recognized by the mouse immune system, by raising a panel of 12 monoclonal antibodies (MAbs) against this protein. Interaction between OmpA and these MAbs is competitively inhibited with several-hundredfold dilutions of mouse polyclonal sera obtained by immunization with live or heat-killed whole cells, suggesting that OmpA is one of the immunodominant antigens of serovar Typhimurium. All of the MAbs were specific for an identical epitope(s) located on the C-terminal domain of OmpA, as indicated by the use of OmpA fragments generated by protease or cyanogen bromide treatment and by competitive inhibition enzyme-linked immunosorbent assay. This epitope was highly conserved within (but not outside) the family Enterobacteriaceae: The strong immunogenicity of this epitope was surprising because the C-terminal domain of OmpA, usually thought to be located in the periplasm, is not expected to be exposed on the bacterial cell surface. A MAb, however, reacted in a cytofluorometry assay more strongly with outer-membrane-permeabilized cells than with untreated cells, a result supporting the predominantly periplasmic localization of the epitope. Significant, though low-level, reactivity of intact cells nevertheless suggests that in some cells the C-terminal domain of OmpA is exposed on the surface, a result consistent with the proposal that OmpA can fold into one of the two alternate conformations.
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Singh SP, Williams YU, Miller S, Nikaido H. The C-terminal domain of Salmonella enterica serovar typhimurium OmpA is an immunodominant antigen in mice but appears to be only partially exposed on the bacterial cell surface. Infect Immun 2003; 71:3937-46. [PMID: 12819080 PMCID: PMC161966 DOI: 10.1128/iai.71.7.3937-3946.2003] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We examined the way the major outer membrane protein OmpA of Salmonella enterica serovar Typhimurium is recognized by the mouse immune system, by raising a panel of 12 monoclonal antibodies (MAbs) against this protein. Interaction between OmpA and these MAbs is competitively inhibited with several-hundredfold dilutions of mouse polyclonal sera obtained by immunization with live or heat-killed whole cells, suggesting that OmpA is one of the immunodominant antigens of serovar Typhimurium. All of the MAbs were specific for an identical epitope(s) located on the C-terminal domain of OmpA, as indicated by the use of OmpA fragments generated by protease or cyanogen bromide treatment and by competitive inhibition enzyme-linked immunosorbent assay. This epitope was highly conserved within (but not outside) the family Enterobacteriaceae: The strong immunogenicity of this epitope was surprising because the C-terminal domain of OmpA, usually thought to be located in the periplasm, is not expected to be exposed on the bacterial cell surface. A MAb, however, reacted in a cytofluorometry assay more strongly with outer-membrane-permeabilized cells than with untreated cells, a result supporting the predominantly periplasmic localization of the epitope. Significant, though low-level, reactivity of intact cells nevertheless suggests that in some cells the C-terminal domain of OmpA is exposed on the surface, a result consistent with the proposal that OmpA can fold into one of the two alternate conformations.
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Affiliation(s)
- Shiva P Singh
- Biomedical Research and Training Programs, Alabama State University, Montgomery, Alabama 36101, USA.
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40
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Feodorova VA, Samelija JG, Devdariani ZL. Heat-stable serogroup-specific proteins of Yersinia pseudotuberculosis. J Med Microbiol 2003; 52:389-395. [PMID: 12721314 DOI: 10.1099/jmm.0.05036-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
A library of mAbs to the species- and serogroup-specific epitopes of Yersinia pseudotuberculosis serogroups I-VI was developed. These mAbs recognized linear sequential protein epitopes, as shown by ELISA and immunoblotting. Using the mAbs, Y. pseudotuberculosis was found to produce serogroup-specific proteins, whose synthesis was dependent on cultivation temperature. These proteins appeared to be parts of heat-stable O-antigens prepared by heating Y. pseudotuberculosis serogroups I-VI at 100 degrees C for 2 h, and are responsible for the protein serotype specificity of these bacteria. The high specificity of serogroup- or species-specific mAbs obtained in ELISA suggests that they may be effective for serotyping of Y. pseudotuberculosis strains or differentiation from other pathogenic yersiniae.
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Affiliation(s)
- V A Feodorova
- Laboratory of Hybridomas, Russia State Antiplague Research Institute 'Microbe', Saratov, Russia
| | - J G Samelija
- Laboratory of Hybridomas, Russia State Antiplague Research Institute 'Microbe', Saratov, Russia
| | - Z L Devdariani
- Laboratory of Hybridomas, Russia State Antiplague Research Institute 'Microbe', Saratov, Russia
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Davies RL, MacCorquodale R, Caffrey B. Diversity of avian Pasteurella multocida strains based on capsular PCR typing and variation of the OmpA and OmpH outer membrane proteins. Vet Microbiol 2003; 91:169-82. [PMID: 12458166 PMCID: PMC7117370 DOI: 10.1016/s0378-1135(02)00300-0] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
One hundred avian Pasteurella multocida isolates recovered from cases of fowl cholera and related infections in England and Wales over a 13-year period were characterised by capsular PCR typing and analysis of outer membrane protein (OMP) profiles. Sixty-eight percent of the strains were of capsular type A, 14% were type F, 5% were type D, 4% were type B and 9% were untypable. Nineteen distinct OMP profiles (OMP-types) were identified based mainly on molecular mass heterogeneity of the heat-modifiable (OmpA) and porin (OmpH) proteins. Fifty-six percent of the isolates were represented by 15 OMP-types, whereas 44% of the isolates were associated with four OMP-types. The extensive molecular mass heterogeneity of the OmpA and OmpH proteins supports previous findings that avian P. multocida strains are very diverse. Furthermore, the isolates studied were associated with different clinical symptoms and were recovered from a wide range of lesions and tissues. The high degree of strain diversity together with the wide variety of clinical symptoms suggest that certain avian strains of P. multocida are opportunistic pathogens of relatively low virulence. Strains of capsular types B, D and F, as well as the untypable isolates, were associated exclusively with specific OMP-types and represent distinct and widely disseminated clonal groups. These observations support the view that avian strains of P. multocida have a clonal population structure. Based on previous studies, the molecular mass heterogeneity of the OmpA and OmpH proteins might provide a selective advantage to P. multocida by generating antigenic variation.
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Affiliation(s)
- Robert L Davies
- Division of Infection and Immunity, Institute of Biomedical and Life Sciences, Joseph Black Building, University of Glasgow, G12 8QQ, Glasgow, UK.
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Davies RL, MacCorquodale R, Baillie S, Caffrey B. Characterization and comparison of Pasteurella multocida strains associated with porcine pneumonia and atrophic rhinitis. J Med Microbiol 2003; 52:59-67. [PMID: 12488567 DOI: 10.1099/jmm.0.05019-0] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
One hundred and fifty-eight porcine strains of Pasteurella multocida, recovered primarily from cases of pneumonic pasteurellosis or progressive atrophic rhinitis (PAR) in England and Wales, were characterized by determination of their capsular types, presence or absence of the toxA gene and molecular mass heterogeneity of the heat-modifiable (OmpA) and porin (OmpH) proteins. Eighteen groups (clones) of strains were identified on the basis of specific combinations of capsular type, toxA status and outer-membrane protein (OMP)-type. The data provided evidence that different subpopulations of P. multocida are responsible for pneumonia and PAR in pigs. The majority (88 %) of cases of pneumonia were associated exclusively with non-toxigenic capsular type A strains of OMP-types 1.1, 2.1, 3.1 and 5.1 and capsular type D isolates of OMP-type 6.1. These strains were recovered from widespread geographical locations within England and Wales over a 12-year period and represented mostly single sporadic cases. The association of a small number of P. multocida variants with the majority of cases of porcine pneumonia suggests that these strains are not opportunistic pathogens of low virulence but represent primary pathogens with a relatively high degree of virulence. In contrast, the majority (76 %) of cases of PAR were associated with toxA-containing capsular type D strains of OMP-type 4.1 and capsular type A and D strains of OMP-type 6.1. Toxigenic capsular type A strains associated with PAR and non-toxigenic capsular type A strains associated with pneumonia represent distinct subpopulations of P. multocida that can be differentiated by their OMP-types. The association of capsular types A and D with strains of the same OMP-types, and the absence and presence of the toxA gene in strains of the same OMP-types, suggest that horizontal transfer of capsular biosynthesis and toxA genes has occurred between strains representing certain subpopulations of P. multocida.
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Affiliation(s)
- Robert L Davies
- Division of Infection and Immunity, Institute of Biomedical and Life Sciences, Joseph Black Building, University of Glasgow, Glasgow G12 8QQ, UK
| | - Roslyn MacCorquodale
- Division of Infection and Immunity, Institute of Biomedical and Life Sciences, Joseph Black Building, University of Glasgow, Glasgow G12 8QQ, UK
| | - Susan Baillie
- Division of Infection and Immunity, Institute of Biomedical and Life Sciences, Joseph Black Building, University of Glasgow, Glasgow G12 8QQ, UK
| | - Bridget Caffrey
- Division of Infection and Immunity, Institute of Biomedical and Life Sciences, Joseph Black Building, University of Glasgow, Glasgow G12 8QQ, UK
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Identification of an OmpA Protein from Bacteroides fragilis: omp A Gene Sequence, OmpA Amino Acid Sequence and Predictions of Protein Structure. Anaerobe 2002. [DOI: 10.1006/anae.2002.0427] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Toren A, Segal G, Ron EZ, Rosenberg E. Structure--function studies of the recombinant protein bioemulsifier AlnA. Environ Microbiol 2002; 4:257-61. [PMID: 12030851 DOI: 10.1046/j.1462-2920.2002.00298.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Acinetobacter radioresistens KA53 produces an extracellular bioemulsifier, referred to as alasan. The surface active component of alasan is a 35.77 kDa protein AlnA. Although AlnA and the Escherichia coli outer membrane protein A (OmpA) have a high amino acid sequence homology, E. coli OmpA has no emulsifying activity. Comparison of the amino acid sequences of AlnA and E. coli OmpA revealed four hydrophobic regions in AlnA that were absent in E. coli OmpA. Deletions and substitutions (with the homologous OmpA sequence) were constructed in each of the four hydrophobic regions of AlnA by site-directed polymerase chain reaction (PCR) mutagenesis, using the overlap PCR method. Analysis of the emulsifying activities of the mutated AlnA molecules demonstrated that all four hydrophobic regions were necessary for emulsifying activity. However, most of the inactive mutated proteins still adhered avidly to hexadecane. These findings indicate that in addition to binding to hydrocarbons, the protein emulsifier must form a specific structure on the surface of the hydrocarbon that prevents coalescence of oil droplets. This is the first structure-function study of a protein bioemulsifer.
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Affiliation(s)
- Amir Toren
- Department of Molecular Microbiology and Biotechnology, Tel Aviv University, Ramat Aviv, Israel 69978.
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Abstract
Outer membrane protein A (OmpA) is a major protein in the Escherichia coli outer membrane. In this study, the function of OmpA in E. coli stress survival was examined. An E. coli K1 ompA-deletion mutant was significantly more sensitive than that of its parent strain to sodium dodecyl sulfate (SDS), cholate, acidic environment, high osmolarity, and pooled human serum. A number of amino acid changes at the extracellular loops of OmpA did not affect the viability of E. coli, while short peptide insertions in the periplasmic turns of the OmpA beta-barrel decreased E. coli resistance to environmental stresses. Moreover, ompA mutants were found to survive much better within brain microvascular endothelial cells than the wild-type strain, supporting that OmpA is a major target in mammalian host cell defense. These results indicated that OmpA plays a vital structural role in E. coli, and suggested that a perfect beta-barrel structure of OmpA is important for outer membrane stability. Based on these results and the published OmpA structural analyses, I propose that OmpA is composed of three functional domains including a hydrophilic extracellular mass, a beta-barrel transmembrane structure, and a peptidoglycan binding domain.
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Affiliation(s)
- Ying Wang
- University of Southern California School of Dentistry, 925 W. 34th Street, Los Angeles, California 9008, USA.
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Jolodar A, Miller DJ. Construction and expression of aspartic protease from Onchocerca volvulus* as ompA fusion protein in a mutant strain of Salmonella typhimurium. Genet Mol Biol 2002. [DOI: 10.1590/s1415-47572002000100018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Affiliation(s)
- Abbas Jolodar
- Shahid Chamran University, Iran; Bernhard Nocht Institute for Tropical Medicine, Germany
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Toren A, Orr E, Paitan Y, Ron EZ, Rosenberg E. The active component of the bioemulsifier alasan from Acinetobacter radioresistens KA53 is an OmpA-like protein. J Bacteriol 2002; 184:165-70. [PMID: 11741856 PMCID: PMC134766 DOI: 10.1128/jb.184.1.165-170.2002] [Citation(s) in RCA: 47] [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
The bioemulsifier of Acinetobacter radioresistens KA53, referred to as alasan, is a high-molecular-weight complex of polysaccharide and protein. Recently, one of the alasan proteins, with an apparent molecular mass of 45 kDa, was purified and shown to constitute most of the emulsifying activity. The N-terminal sequence of the 45-kDa protein showed high homology to an OmpA-like protein from Acinetobacter spp. In the research described here the gene coding for the 45-kDa protein was cloned, sequenced, and expressed in Escherichia coli. Recombinant protein AlnA (35.77 kDa without the leader sequence) had an amino acid sequence homologous to that of E. coli OmpA and contained 70% of the specific (hydrocarbon-in-water) emulsifying activity of the native 45-kDa protein and 2.4 times that of the alasan complex. In addition to their emulsifying activity, both the native 45-kDa protein and the recombinant AlnA were highly effective in solubilizing phenanthrene, ca. 80 microg per mg of protein, corresponding to 15 to 19 molecules of phenanthrene per molecule of protein. E. coli OmpA had no significant emulsifying or phenanthrene-solubilizing activity. The production of a recombinant surface-active protein (emulsification and solubilization of hydrocarbons in water) from a defined gene makes possible for the first time structure-function studies of a bioemulsan.
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Affiliation(s)
- Amir Toren
- Department of Molecular Microbiology and Biotechnology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Ramat Aviv, Israel 69978
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Toren A, Navon-Venezia S, Ron EZ, Rosenberg E. Emulsifying activities of purified Alasan proteins from Acinetobacter radioresistens KA53. Appl Environ Microbiol 2001; 67:1102-6. [PMID: 11229898 PMCID: PMC92701 DOI: 10.1128/aem.67.3.1102-1106.2001] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The bioemulsifier of Acinetobacter radioresistens KA53, referred to as alasan, is a high-molecular-weight complex of polysaccharide and protein. The emulsifying activity of the purified polysaccharide (apo-alasan) is very low. Three of the alasan proteins were purified by preparative sodium dodecyl sulfate-polyacrylamide gel electrophoresis and had apparent molecular masses of 16, 31, and 45 kDa. Emulsification assays using the isolated alasan proteins demonstrated that the active components of the alasan complex are the proteins. The 45-kDa protein had the highest specific emulsifying activity, 11% higher than the intact alasan complex. The 16- and 31-kDa proteins gave relatively low emulsifying activities, but they were significantly higher than that of apo-alasan. The addition of the purified 16- and 31-kDa proteins to the 45-kDa protein resulted in a 1.8-fold increase in the specific emulsifying activity and increased stability of the oil-in-water emulsion. Fast-performance liquid chromatography analysis indicated that the 45-kDa protein forms a dimer in nondenaturing conditions and interacts with the 16- and 31-kDa proteins to form a high-molecular-mass complex. The 45-kDa protein and the three-protein complex had substrate specificities for emulsification and a range of pH activities similar to that of alasan. The fact that the purified proteins are active emulsifiers should simplify structure-function studies and advance our understanding of their biological roles.
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Affiliation(s)
- A Toren
- Department of Molecular Microbiology and Biotechnology, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Ramat Aviv 69978, Israel
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Ofori-Darko E, Zavros Y, Rieder G, Tarlé SA, Van Antwerp M, Merchant JL. An OmpA-like protein from Acinetobacter spp. stimulates gastrin and interleukin-8 promoters. Infect Immun 2000; 68:3657-66. [PMID: 10816525 PMCID: PMC97656 DOI: 10.1128/iai.68.6.3657-3666.2000] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Bacterial overgrowth in the stomach may occur under conditions of diminished or absent acid secretion. Under these conditions, secretion of the hormone gastrin is elevated. Alternatively, bacterial factors may directly stimulate gastrin. Consistent with this hypothesis, we found that mice colonized for 2 months with a mixed bacterial culture of opportunistic pathogens showed an increase in serum gastrin. To examine regulation of gene expression by bacterial proteins, stable transformants of AGS cells expressing gastrin or interleukin-8 (IL-8) promoters were cocultured with live organisms. Both whole-cell sonicates and a heat-stable fraction were also coincubated with the cells. A level of 10(8) organisms per ml stimulated both the gastrin and IL-8 promoters. Heat-stable proteins prepared from these bacterial sonicates stimulated the promoter significantly more than the live organism or unheated sonicates. A 38-kDa heat-stable protein stimulating the gastrin and IL-8 promoters was cloned and found to be an OmpA-related protein. Immunoblotting using antibody to the OmpA-like protein identified an Acinetobacter sp. as the bacterial species that expressed this protein and colonized the mouse stomach. Moreover, reintubation of mice with a pure culture of the Acinetobacter sp. caused gastritis. We conclude that bacterial colonization of the stomach may increase serum gastrin levels in part through the ability of the bacteria to produce OmpA-like proteins that directly stimulate gastrin and IL-8 gene expression. These results implicate OmpA-secreting bacteria in the activation of gastrin gene expression and raise the possibility that a variety of organisms may contribute to the increase in serum gastrin and subsequent epithelial cell proliferation in the hypochlorhydric stomach.
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Affiliation(s)
- E Ofori-Darko
- Departments of Internal Medicine, University of Michigan, Ann Arbor, Michigan, USA
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Hellman J, Loiselle PM, Tehan MM, Allaire JE, Boyle LA, Kurnick JT, Andrews DM, Sik Kim K, Warren HS. Outer membrane protein A, peptidoglycan-associated lipoprotein, and murein lipoprotein are released by Escherichia coli bacteria into serum. Infect Immun 2000; 68:2566-72. [PMID: 10768945 PMCID: PMC97460 DOI: 10.1128/iai.68.5.2566-2572.2000] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Complexes containing lipopolysaccharide (LPS) and three outer membrane proteins (OMPs) are released by gram-negative bacteria incubated in human serum and into the circulation in an experimental model of sepsis. The same OMPs are bound by immunoglobulin G (IgG) in the cross-protective antiserum raised to Escherichia coli J5 (anti-J5 IgG). This study was performed to identify the three OMPs. The 35-kDa OMP was identified as outer membrane protein A (OmpA) by immunoblotting studies using OmpA-deficient bacteria and recombinant OmpA protein. The 18-kDa OMP was identified as peptidoglycan-associated lipoprotein (PAL) based on peptide sequences from the purified protein and immunoblotting studies using PAL-deficient bacteria. The 5- to 9-kDa OMP was identified as murein lipoprotein (MLP) based on immunoblotting studies using MLP-deficient bacteria. The studies identify the OMPs released into human serum and into the circulation in an experimental model of sepsis as OmpA, PAL, and MLP.
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Affiliation(s)
- J Hellman
- Department of Infectious Diseases, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, USA.
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