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Deka NJ, Kalita DJ, Tamuly S, Sharma RK, Bora DP, Dutta R, Hazorika M, Chabukdhara P, George S. Calcium phosphate nanoparticles conjugated with outer membrane vesicle of Riemerella anatipestifer for vaccine development in ducklings. Microb Pathog 2023; 185:106446. [PMID: 37951409 DOI: 10.1016/j.micpath.2023.106446] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2023] [Revised: 10/14/2023] [Accepted: 11/06/2023] [Indexed: 11/14/2023]
Abstract
Biodegradable calcium phosphate nanoparticles offer a viable substitute for traditional adjuvants such as aluminum in vaccine production. Calcium phosphate nanoparticle adjuvanted with outer membrane vesicle (OMV) of gram negative bacteria may induce efficient immune response in the host. The present study was carried out to evaluate the potential of a mucosal vaccine formulation of calcium phosphate (CAP) nanoparticle using OMV of Riemerella anatipestifer (RA) as antigen against New Duck disease in ducks. The work was initiated with isolation, identification of RA, followed by OMV production and extraction. The CAP-OMV nanoparticle was prepared and characterized. The efficacy of the vaccine formulation and toxicity were studied in ducks. The average OMV yield in terms of protein concentration was found to be 122.33 ± 3.48 mg per liter of BHI broth. In SDS-PAGE, isolated OMVs exhibited presence of 16 distinct protein bands with molecular weight ranging from 142.1 to 12.1 kDa. Seven protein bands of 74.1, 69.3, 55.5, 50.6, 45.6, 25.1 and 13.1 kDa were detected relatively more distinct. The major bands detected in our findings were 42 kDa, 37 kDa and 16 kDa that corresponds to OmpA, OmpH, P6 respectively. The mean zeta size (±SD) and potential of the nanoparticle were 246.20 ± 0.53 nm and -25.60 ± 5.97 respectively. In transmission electron microscopy (TEM), the nanoparticles exhibited an average diameter of 129.80 ± 11.10 nm and displayed spherical morphology. The median protective dose (PD50) of CAP-OMV nanoparticle was 1881.10 μg of protein. Group I ducks received 3762 μg of protein (entrapped protein in CAP-OMV nanoparticle) via intra nasal route and it showed the highest serum IgG and secretory IgA level than other immunized groups. All experimental ducks were challenged with 10 × LD50 on 35 days of post primary immunization. Group I showed 100 % survivability in the challenge study. No gross and biochemical indication of acute or chronic toxicity were recorded. In conclusion, our results suggest that CAP-OMV nanoparticle can be a safe and efficient mucosal vaccine delivery system for RA, eliciting strong immune response in the host.
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Affiliation(s)
- Naba Jyoti Deka
- Department of Veterinary Biochemistry, College of Veterinary Science, Assam Agricultural University, Khanapara, Guwahati, Assam, 781022, India.
| | - Dhruba Jyoti Kalita
- Department of Veterinary Biochemistry, College of Veterinary Science, Assam Agricultural University, Khanapara, Guwahati, Assam, 781022, India
| | - Shantanu Tamuly
- Department of Veterinary Biochemistry, College of Veterinary Science, Assam Agricultural University, Khanapara, Guwahati, Assam, 781022, India
| | - Rajeev Kumar Sharma
- Department of Veterinary Microbiology, College of Veterinary Science, Assam Agricultural University, Khanapara, Guwahati, Assam, 781022, India
| | - Durlav Prasad Bora
- Department of Veterinary Microbiology, College of Veterinary Science, Assam Agricultural University, Khanapara, Guwahati, Assam, 781022, India
| | - Rupam Dutta
- Department of Animal Biotechnology, College of Veterinary Science, Assam Agricultural University, Khanapara, Assam, 781022, India
| | - Mousumi Hazorika
- Department of Veterinary Biochemistry, College of Veterinary Science, Assam Agricultural University, Khanapara, Guwahati, Assam, 781022, India
| | - Prasanta Chabukdhara
- Department of Veterinary Physiology & Biochemistry, Lakhimpur College of Veterinary Science, Assam Agricultural University, North Lakhimpur, Assam, 787 051, India
| | - Shiney George
- Department of Veterinary Microbiology, College of Veterinary Science, Assam Agricultural University, North Lakhimpur, Assam, 787051, India
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Li Q, Hu Y, Fei X, Du Y, Guo W, Chu D, Wang X, Wang S, Shi H. OmpC, a novel factor H-binding surface protein, is dispensable for the adherence and virulence of Salmonella enterica serovar Typhimurium. Vet Microbiol 2021; 259:109157. [PMID: 34197978 DOI: 10.1016/j.vetmic.2021.109157] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Accepted: 06/15/2021] [Indexed: 11/24/2022]
Abstract
Salmonella enterica serovar Typhimurium utilizes a series of strategies to evade host innate immune defenses, including the serum complement system. Many microbial pathogens have evolved the ability to bind the complement regulatory protein factor H (FH) through their surface factor H-binding proteins (FHBPs) to circumvent the complement-mediated bactericidal effect. However, the roles of FHBPs in Salmonella pathogenesis are not well understood. In this study, we demonstrated that the survival of S. Typhimurium in human serum was decreased in a time and concentration dependent manner. Pre-incubation with FH attenuated the sensitivity of S. Typhimurium strain χ3761 to complement-mediated serum killing, suggesting FH binding enhance survival in serum. We aimed to identify novel S. Typhimurium FHBPs and characterize their biological functions. Here, six potential FHBPs were identified by two-dimensional (2D)-Far-western blot, and three of them were further confirmed to bind FH by Far-western blot and dot blot. We found that deletion of ompC (ΔompC) significantly inhibited the survival of S. Typhimurium strain χ3761 in human serum. Our results indicated that the ompC mutation does not affect χ3761 adhesion to HeLa cells. Furthermore, a mice infection model showed that deletion of ompC had no significant effect on the histopathological lesions or viability compared with the wild-type strain χ3761. In summary, these results suggested that OmpC is an important FHBP, but not a critical virulence factor of S. Typhimurium.
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Affiliation(s)
- Quan Li
- College of Veterinary Medicine, Yangzhou University, Yangzhou, 225009, Jiangsu, China; Jiangsu Co-Innovation Center for the Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, 225009, China.
| | - Yuhan Hu
- College of Veterinary Medicine, Yangzhou University, Yangzhou, 225009, Jiangsu, China; Jiangsu Co-Innovation Center for the Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, 225009, China.
| | - Xia Fei
- College of Veterinary Medicine, Yangzhou University, Yangzhou, 225009, Jiangsu, China; Jiangsu Co-Innovation Center for the Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, 225009, China.
| | - Yuanzhao Du
- Yebio Bioengineering Co., Ltd of Qingdao, Qingdao, 266114, China.
| | - Weiwei Guo
- Yebio Bioengineering Co., Ltd of Qingdao, Qingdao, 266114, China.
| | - Dianfeng Chu
- Yebio Bioengineering Co., Ltd of Qingdao, Qingdao, 266114, China.
| | - Xiaobo Wang
- College of Veterinary Medicine, Yangzhou University, Yangzhou, 225009, Jiangsu, China; Jiangsu Co-Innovation Center for the Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, 225009, China.
| | - Shifeng Wang
- Department of Infectious Diseases and Immunology, College of Veterinary Medicine, University of Florida, Gainesville, FL, 32611-0880, USA.
| | - Huoying Shi
- College of Veterinary Medicine, Yangzhou University, Yangzhou, 225009, Jiangsu, China; Jiangsu Co-Innovation Center for the Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, 225009, China; Key Laboratory of Animal Infectious Diseases, Ministry of Agriculture, Yangzhou University, China; Jiangsu Key Laboratory of Preventive Veterinary Medicine, Yangzhou University, China.
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Renu S, Markazi AD, Dhakal S, Lakshmanappa YS, Gourapura SR, Shanmugasundaram R, Senapati S, Narasimhan B, Selvaraj RK, Renukaradhya GJ. Surface engineered polyanhydride-based oral Salmonella subunit nanovaccine for poultry. Int J Nanomedicine 2018; 13:8195-8215. [PMID: 30555234 PMCID: PMC6280892 DOI: 10.2147/ijn.s185588] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
PURPOSE Salmonellosis is a severe economic threat in poultry and a public health concern. Currently available vaccines are ineffective, and thus, developing effective oral Salmonella vaccine is warranted. Especially, a potent oral vaccine such as the mucoadhesive polyanhydride nanoparticle (PNP) protects the vaccine cargo and delivers to intestinal immune sites to elicit robust mucosal immunity and mitigate Salmonella colonization and shedding. MATERIALS AND METHODS We designed a Salmonella subunit vaccine using PNP containing immunogenic Salmonella outer membrane proteins (OMPs) and flagellar (F) protein-entrapped and surface F-protein-coated PNPs (OMPs-F-PNPs) using a solvent displacement method. Using high-throughput techniques, we characterized the OMPs-F-PNPs physicochemical properties and analyzed its efficacy in layer birds vaccinated orally. RESULTS The candidate vaccine was resistant in acidic microenvironment and had ideal physicochemical properties for oral delivery in terms of particle size, charge, morphology, biocompatibility, and pH stability. In vitro, in vivo, and ex vivo studies showed that F-protein surface-anchored nanoparticles were better targeted to chicken immune cells in peripheral blood and splenocytes and intestinal Peyer's patch sites. In layer chickens inoculated orally with OMPs-F-PNPs, substantially higher OMPs-specific IgG response and secretion of Th1 cytokine IFN-γ in the serum, enhanced CD8+/CD4+ cell ratio in spleen, and increased OMPs-specific lymphocyte proliferation were observed. OMPs-F-PNPs vaccination also upregulated the expression of toll-like receptor (TLR)-2 and -4, TGF-β, and IL-4 cytokines' genes in chicken cecal tonsils (lymphoid tissues). Importantly, OMPs-F-PNPs vaccine cleared Salmonella cecal colonization in 33% of vaccinated birds. CONCLUSION This pilot in vivo study demonstrated the targeted delivery of OMPs-F-PNPs to ileum mucosal immune sites of chickens and induced specific immune response to mitigate Salmonella colonization in intestines.
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Affiliation(s)
- Sankar Renu
- Food Animal Health Research Program, Ohio Agricultural Research and Development Center, The Ohio State University, Wooster, OH 44691, USA,
- Department of Veterinary Preventive Medicine, College of Veterinary Medicine, The Ohio State University, Columbus, OH 43210, USA,
| | - Ashley D Markazi
- Department of Animal Sciences, Ohio Agricultural Research and Development Center, The Ohio State University, Wooster, OH 44691, USA
| | - Santosh Dhakal
- Food Animal Health Research Program, Ohio Agricultural Research and Development Center, The Ohio State University, Wooster, OH 44691, USA,
- Department of Veterinary Preventive Medicine, College of Veterinary Medicine, The Ohio State University, Columbus, OH 43210, USA,
| | - Yashavanth S Lakshmanappa
- Food Animal Health Research Program, Ohio Agricultural Research and Development Center, The Ohio State University, Wooster, OH 44691, USA,
- Department of Veterinary Preventive Medicine, College of Veterinary Medicine, The Ohio State University, Columbus, OH 43210, USA,
| | - Suren R Gourapura
- Food Animal Health Research Program, Ohio Agricultural Research and Development Center, The Ohio State University, Wooster, OH 44691, USA,
- Department of Veterinary Preventive Medicine, College of Veterinary Medicine, The Ohio State University, Columbus, OH 43210, USA,
| | - Revathi Shanmugasundaram
- Department of Animal Sciences, Ohio Agricultural Research and Development Center, The Ohio State University, Wooster, OH 44691, USA
| | - Sujata Senapati
- Department of Chemical and Biological Engineering, Iowa State University, Ames, IA 50011, USA
| | - Balaji Narasimhan
- Department of Chemical and Biological Engineering, Iowa State University, Ames, IA 50011, USA
| | - Ramesh K Selvaraj
- Department of Poultry Science, University of Georgia, Athens, GA 30602, USA,
| | - Gourapura J Renukaradhya
- Food Animal Health Research Program, Ohio Agricultural Research and Development Center, The Ohio State University, Wooster, OH 44691, USA,
- Department of Veterinary Preventive Medicine, College of Veterinary Medicine, The Ohio State University, Columbus, OH 43210, USA,
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Talukdar S, Bayan U, Saikia KK. In silico identification of vaccine candidates against Klebsiella oxytoca. Comput Biol Chem 2017; 69:48-54. [PMID: 28570984 DOI: 10.1016/j.compbiolchem.2017.05.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2015] [Revised: 05/06/2017] [Accepted: 05/20/2017] [Indexed: 01/10/2023]
Abstract
Klebsiella oxytoca causes several diseases in immunocompromised as well as healthy individuals. Increasing resistance to a number of antibiotics makes treatment options limited. Prevention using vaccine could be an important solution to get rid of infections caused by Klebsiella oxytoca. In recent time, genome based approaches have contributed significantly in vaccine development. Our aim was to identify the most conserved and immunogenic antigens that can be considered as potential vaccine candidates. KEGG database was used to find out pathways unique to the bacteria. Subcellular localization of the protein sequences taken from the selected 36 pathways were predicted using PSORTb v3.0.2 and CELLO v2.5. Prediction of B cell epitope and the probability of the antigenicity were evaluated by using IEDB and Vaxijen respectively. BLASTp was done to find out the similarity of the selected proteins with the human proteome. Proteins failing to comply with the set parameters were filtered at each step. Finally, we identified 6 surface exposed proteins as potential vaccine candidates against Klebsiella oxytoca.
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Affiliation(s)
- Sandipan Talukdar
- Dept of Bioengineering & Technology, GUIST, Gauhati University, India
| | - Udeshna Bayan
- Dept of Bioengineering & Technology, GUIST, Gauhati University, India
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Thulasingam M, Damodharan S, Madhana Vigneshwari G, P J Pandaranayaka E, Elizabeth Hanna L, Usha R, Krishnaswamy S. Characterization of Salmonella typhi OmpC and OmpF porins engineered with HIV-gp41 epitope on the surface loops. Proteins 2017; 85:657-664. [PMID: 28076882 DOI: 10.1002/prot.25246] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Revised: 11/29/2016] [Accepted: 12/18/2016] [Indexed: 11/11/2022]
Abstract
Porins form trimers in the outer membrane and help transport nutrients and waste products across the bacterial cell membrane. Porin loops are suitable candidates as display systems due to their high immunogenicity and presentation at the bacterial cell surface. In this study, Salmonella typhi porins (OmpC and OmpF) engineered with the Kennedy peptide from gp41 of HIV were characterised. The chimeric OmpC carrying the Kennedy peptide in loop7 did not trimerise, whereas the chimeric OmpF with the epitope in loop5 formed trimers and also was recognised by the antibodies in the HIV patient serum. The results suggest that chimeric S. typhi OmpF may be taken further as a potential candidate to develop as an epitope display system. Proteins 2017; 85:657-664. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
| | - Subha Damodharan
- School of Biotechnology, Madurai Kamaraj University, Madurai, 625021, India
| | | | | | - Luke Elizabeth Hanna
- National Institute for Research in Tuberculosis, Indian Council of Medical Research, Chennai, 600031, India
| | - Ramakrishnan Usha
- School of Biotechnology, Madurai Kamaraj University, Madurai, 625021, India
| | - Sankaran Krishnaswamy
- School of Biotechnology, Madurai Kamaraj University, Madurai, 625021, India.,Institute of Mathematical Sciences, Chennai, 600113, India
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Evaluation of recombinant outer membrane protein based vaccine against Salmonella Typhimurium in birds. Biologicals 2013; 41:162-8. [DOI: 10.1016/j.biologicals.2013.01.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2011] [Revised: 10/15/2012] [Accepted: 01/12/2013] [Indexed: 11/17/2022] Open
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Jha R, Kumar A, Saxena A, Tamuly S, Saxena MK. Cloning, sequencing and in silico analysis of omp C of salmonella typhimurium. ISRN VETERINARY SCIENCE 2012; 2012:512848. [PMID: 23762587 PMCID: PMC3658560 DOI: 10.5402/2012/512848] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/22/2011] [Accepted: 12/26/2011] [Indexed: 11/23/2022]
Abstract
Salmonella Typhimurium is an important pathogen having a broad host range. In human population it causes mostly gastroenteritis but there are reports in which it was found to be responsible to cause several lethal diseases like endocarditis and meningitis. Poultry products are the major sources of this organism in India as these are consumed at various stages of cooking. The available vaccines have their own limitations such as short-term immunity. Outer membrane proteins have shown some promising potential, so in the present study Omp C of Salmonella Typhimurium was cloned and sequenced to explore the possibility of development of r-DNA vaccine against Salmonella Typhimurium for poultry. The sequence of Omp C was studied for antigenic indexing, epitope mapping, and MHC mapping using various bioinformatic tools. The ORF analysis revealed a complete coding region of approximately 1000 bp. Five major and 13 minor B-cell epitopes were identified having an antigenic index of 1.7. The sequences also showed major histocompatibility complex (MHC) class I and class II binding region indicating a potential of eliciting cell-mediated immune response. The findings indicate that Omp C may be proven as promising candidate for development of r-DNA vaccine against Salmonella Typhimurium.
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Affiliation(s)
- Richa Jha
- Department of Molecular Biology and Genetic Engineering, G.B. Pant University of Agriculture & Technology, Pantnagar 263145, India
| | - Anil Kumar
- Department of Molecular Biology and Genetic Engineering, G.B. Pant University of Agriculture & Technology, Pantnagar 263145, India
| | - Anjani Saxena
- Animal Biotechnology Center, Department of Veterinary Physiology & Biochemistry, G.B. Pant University of Agriculture & Technology, Pantnagar 263145, India
| | - Shantanu Tamuly
- Animal Biotechnology Center, Department of Veterinary Physiology & Biochemistry, G.B. Pant University of Agriculture & Technology, Pantnagar 263145, India
| | - M. K. Saxena
- Animal Biotechnology Center, Department of Veterinary Physiology & Biochemistry, G.B. Pant University of Agriculture & Technology, Pantnagar 263145, India
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Shrivastava R, Basu B, Godbole A, Mathew MK, Apte SK, Phale PS. Repression of the glucose-inducible outer-membrane protein OprB during utilization of aromatic compounds and organic acids in Pseudomonas putida CSV86. MICROBIOLOGY-SGM 2011; 157:1531-1540. [PMID: 21330430 DOI: 10.1099/mic.0.047191-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Pseudomonas putida CSV86 shows preferential utilization of aromatic compounds over glucose. Protein analysis and [¹⁴C]glucose-binding studies of the outer membrane fraction of cells grown on different carbon sources revealed a 40 kDa protein that was transcriptionally induced by glucose and repressed by aromatics and succinate. Based on 2D gel electrophoresis and liquid chromatography-tandem mass spectrometry analysis, the 40 kDa protein closely resembled the porin B of P. putida KT2440 and carbohydrate-selective porin OprB of various Pseudomonas strains. The purified native protein (i) was estimated to be a homotrimer of 125 kDa with a subunit molecular mass of 40 kDa, (ii) displayed heat modifiability of electrophoretic mobility, (iii) showed channel conductance of 166 pS in 1 M KCl, (iv) permeated various sugars (mono-, di- and tri-saccharides), organic acids, amino acids and aromatic compounds, and (v) harboured a glucose-specific and saturable binding site with a dissociation constant of 1.3 µM. These results identify the glucose-inducible outer-membrane protein of P. putida CSV86 as a carbohydrate-selective protein OprB. Besides modulation of intracellular glucose-metabolizing enzymes and specific glucose-binding periplasmic space protein, the repression of OprB by aromatics and organic acids, even in the presence of glucose, also contributes significantly to the strain's ability to utilize aromatics and organic acids over glucose.
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Affiliation(s)
- Rahul Shrivastava
- Department of Biosciences and Bioengineering, Indian Institute of Technology-Bombay, Powai, Mumbai 400 076, India
| | - Bhakti Basu
- Molecular Biology Division, Bhabha Atomic Research Center, Trombay, Mumbai 400 085, India
| | - Ashwini Godbole
- National Center for Biological Sciences, Bangalore 560 065, India
| | - M K Mathew
- National Center for Biological Sciences, Bangalore 560 065, India
| | - Shree K Apte
- Molecular Biology Division, Bhabha Atomic Research Center, Trombay, Mumbai 400 085, India
| | - Prashant S Phale
- Department of Biosciences and Bioengineering, Indian Institute of Technology-Bombay, Powai, Mumbai 400 076, India
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Freeman TC, Landry SJ, Wimley WC. The prediction and characterization of YshA, an unknown outer-membrane protein from Salmonella typhimurium. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2010; 1808:287-97. [PMID: 20863811 DOI: 10.1016/j.bbamem.2010.09.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 06/12/2010] [Revised: 09/13/2010] [Accepted: 09/15/2010] [Indexed: 11/27/2022]
Abstract
We have developed an effective pathway for the prediction and characterization of novel transmembrane β-barrel proteins. The Freeman-Wimley algorithm, which is a highly accurate prediction method based on the physicochemical properties of experimentally characterized transmembrane β barrel (TMBB) structures, was used to predict TMBBs in the genome of Salmonella typhimurium LT2. The previously uncharacterized product of gene yshA was tested as a model for validating the algorithm. YshA is a highly conserved 230-residue protein that is predicted to have 10 transmembrane β-strands and an N-terminal signal sequence. All of the physicochemical and spectroscopic properties exhibited by YshA are consistent with the prediction that it is a TMBB. Specifically, recombinant YshA localizes to the outer membrane when expressed in Escherichia coli; YshA has a β-sheet-rich secondary structure with stable tertiary contacts in the presence of detergent micelles or when reconstituted into a lipid bilayer. When in a lipid bilayer, YshA forms a membrane-spanning pore with an effective radius of ~0.7nm. Taken together, these data substantiate the predictions made by the Freeman-Wimley algorithm by showing that YshA is a TMBB protein.
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Affiliation(s)
- Thomas C Freeman
- Department of Biochemistry, Tulane University Health Sciences Center, 1430 Tulane Ave SL-43, New Orleans, LA 70112, USA
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Soong R, Majonis D, Macdonald PM. Size of bicelle defects probed via diffusion nuclear magnetic resonance of PEG. Biophys J 2009; 97:796-805. [PMID: 19651038 DOI: 10.1016/j.bpj.2009.05.034] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2008] [Revised: 05/27/2009] [Accepted: 05/28/2009] [Indexed: 11/16/2022] Open
Abstract
Diffusion of various poly(ethylene glycol) (PEG) tracers of well-defined molecular weight and narrow polydispersity confined within the aqueous interstices between positively magnetically aligned bicelles was measured using pulsed-field-gradient (1)H nuclear magnetic resonance. The bicelles consisted of mixtures of dimyristoylphosphatidylcholine (DMPC), dimyristoylphosphatidylglycerol (DMPG), and dihexanoylphosphatidylcholine (DHPC) in the molar ratios q = [100 DMPC +5 DMPG]/[DHPC] = 3.5, 4.5, and 5.5, to which Yb(3+) had been added in the ratio 1:75 Yb(3+)/phospholipid. The field gradients were applied such that diffusion was measured in the direction parallel to the normal to the bicelles' planar regions, thereby rendering the experiment sensitive to the ability of PEG to traverse lamellar defects within the bicelles. The pulsed-field-gradient nuclear magnetic resonance diffusive intensity decays were diffusion-time-independent in all cases, with diffusive displacements corresponding to many hundreds of bicellar lamellae. This permitted a description of such diffusive decays in terms of a mean behavior involving a combination of straight obstruction effects common to all PEG, with hindrance to diffusion proportional to the relative size of a given PEG with respect to the size of the lamellar defects. Across the range of PEG molecular weights (200-4600) and bicelle compositions examined, the apparent radial dimension of the lamellar defects decreased from 165 A with q = 3.5 to 125 A with q = 5.5. This is opposite to the trend predicted from static geometric models of either bicelle disks or perforated lamellae. Qualitatively, the observed trend suggests that mobility of the obstructions to diffusion will need to be considered to reconcile these differences.
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Affiliation(s)
- Ronald Soong
- Department of Chemistry, University of Toronto, Toronto, Ontario, Canada
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