scholarly journals Characterization of Pgp3, a Chlamydia trachomatis Plasmid-Encoded Immunodominant Antigen

2010 ◽  
Vol 192 (22) ◽  
pp. 6017-6024 ◽  
Author(s):  
Ding Chen ◽  
Lei Lei ◽  
Chunxue Lu ◽  
Ahmad Galaleldeen ◽  
P. John Hart ◽  
...  
Keyword(s):  
Chlamydia Trachomatis ◽  
Outer Membrane ◽  
Expression System ◽  
Sodium Dodecyl ◽  
Structural Basis ◽  
Human Antibody ◽  
Human Immune System ◽  
Human Antibodies ◽  
Membrane Complex ◽  
Nonionic Detergents

ABSTRACT Human antibody recognition of Chlamydia trachomatis plasmid-encoded Pgp3 protein is dependent on the native conformation of Pgp3. The structural basis for the conformation dependence and the function of Pgp3 remain unknown. Here, we report that Pgp3 trimerization is required for the recognition of Pgp3 by human antibodies. In a native polyacrylamide gel, Pgp3 purified from a bacterial expression system migrated as stable trimers that were dissociated into monomers only by treatment with urea or sodium dodecyl sulfate (SDS) but not nonionic detergents. Human antibodies recognized trimeric but not monomeric Pgp3, suggesting that Pgp3 is presented to the human immune system as trimers during C. trachomatis infection. The endogenous Pgp3 secreted into the chlamydial outer membrane complex or host cell cytosol is always trimerized. Intact Pgp3 trimers were eluted from the outer membrane complex by a combination of nonionic detergents with reducing agents but not by the presence of either alone. These observations have provided important information for further understanding the role of Pgp3 in chlamydial pathogenesis and potentially optimizing Pgp3 as a subunit vaccine candidate antigen.

scholarly journals Chlamydia trachomatis Outer Membrane Complex Protein B (OmcB) Is Processed by the Protease CPAF

2012 ◽  
Vol 195 (5) ◽  
pp. 951-957 ◽  
Author(s):  
S. Hou ◽  
L. Lei ◽  
Z. Yang ◽  
M. Qi ◽  
Q. Liu ◽  
...  
Keyword(s):  
Chlamydia Trachomatis ◽  
Outer Membrane ◽  
Membrane Complex ◽  
Complex Protein ◽  
Protein B

scholarly journals Comparison of genovars and Chlamydia trachomatis infection loads in ocular samples from children in two distinct cohorts in Sudan and Morocco

2021 ◽  
Vol 15 (8) ◽  
pp. e0009655
Author(s):  
Ehsan Ghasemian ◽  
Aleksandra Inic-Kanada ◽  
Astrid Collingro ◽  
Lamiss Mejdoubi ◽  
Hadeel Alchalabi ◽  
...  
Keyword(s):  
Chlamydia Trachomatis ◽  
Outer Membrane ◽  
Real Time ◽  
Bacterial Load ◽  
Protein A ◽  
Healthy Controls ◽  
Geographical Differences ◽  
Chlamydia Trachomatis Infection ◽  
Membrane Complex ◽  
Moroccan Patients

Trachoma is a blinding disease caused by repeated conjunctival infection with different Chlamydia trachomatis (Ct) genovars. Ct B genovars have been associated with more severe trachoma symptoms. Here, we investigated associations between Ct genovars and bacterial loads in ocular samples from two distinct geographical locations in Africa, which are currently unclear. We tested ocular swabs from 77 Moroccan children (28 with trachomatous inflammation-follicular (TF) and 49 healthy controls), and 96 Sudanese children (54 with TF and 42 healthy controls) with a Ct-specific real-time polymerase chain reaction (PCR) assay. To estimate bacterial loads, Ct-positive samples were further processed by multiplex real-time qPCR to amplify the chromosomal outer membrane complex B and plasmid open reading frame 2 of Ct. Genotyping was performed by PCR-based amplification of the outer membrane protein A gene (~1120 base pairs) of Ct and Sanger sequencing. Ct-positivities among the Moroccan and Sudanese patient groups were 60·7% and 31·5%, respectively. Significantly more Sudanese patients than Moroccan patients were genovar A-positive. In contrast, B genovars were significantly more prevalent in Moroccan patients than in Sudanese patients. Significantly higher Ct loads were found in samples positive for B genovars (598·596) than A genovar (51·005). Geographical differences contributed to the distributions of different ocular Ct genovars. B genovars may induce a higher bacterial load than A genovars in trachoma patients. Our findings emphasize the importance of conducting broader studies to elucidate if the noted difference in multiplication abilities are genovar and/or endemicity level dependent.

scholarly journals Structural basis for cancer immunotherapy by the first-in-class checkpoint inhibitor ipilimumab

2017 ◽  
Vol 114 (21) ◽  
pp. E4223-E4232 ◽  
Author(s):  
Udupi A. Ramagopal ◽  
Weifeng Liu ◽  
Sarah C. Garrett-Thomson ◽  
Jeffrey B. Bonanno ◽  
Qingrong Yan ◽  
...  
Keyword(s):  
Metastatic Melanoma ◽  
Checkpoint Inhibitors ◽  
Structural Basis ◽  
Human Antibody ◽  
Human Immune System ◽  
Binding Interface ◽  
Fda Approval ◽  
Wide Range ◽  
Antigen Antibody ◽  
Β Sheet

Rational modulation of the immune response with biologics represents one of the most promising and active areas for the realization of new therapeutic strategies. In particular, the use of function blocking monoclonal antibodies targeting checkpoint inhibitors such as CTLA-4 and PD-1 have proven to be highly effective for the systemic activation of the human immune system to treat a wide range of cancers. Ipilimumab is a fully human antibody targeting CTLA-4 that received FDA approval for the treatment of metastatic melanoma in 2011. Ipilimumab is the first-in-class immunotherapeutic for blockade of CTLA-4 and significantly benefits overall survival of patients with metastatic melanoma. Understanding the chemical and physical determinants recognized by these mAbs provides direct insight into the mechanisms of pathway blockade, the organization of the antigen–antibody complexes at the cell surface, and opportunities to further engineer affinity and selectivity. Here, we report the 3.0 Å resolution X-ray crystal structure of the complex formed by ipilimumab with its human CTLA-4 target. This structure reveals that ipilimumab contacts the front β-sheet of CTLA-4 and intersects with the CTLA-4:Β7 recognition surface, indicating that direct steric overlap between ipilimumab and the B7 ligands is a major mechanistic contributor to ipilimumab function. The crystallographically observed binding interface was confirmed by a comprehensive cell-based binding assay against a library of CTLA-4 mutants and by direct biochemical approaches. This structure also highlights determinants responsible for the selectivity exhibited by ipilimumab toward CTLA-4 relative to the homologous and functionally related CD28.

Membrane proteins PmpG and PmpH are major constituents of Chlamydia trachomatis L2 outer membrane complex

2000 ◽  
Vol 186 (2) ◽  
pp. 163-169 ◽  
Author(s):  
Per Holse Mygind ◽  
Gunna Christiansen ◽  
Peter Roepstorff ◽  
Svend Birkelund
Keyword(s):  
Chlamydia Trachomatis ◽  
Membrane Proteins ◽  
Outer Membrane ◽  
Membrane Complex

scholarly journals Identification of Two Novel Genes Encoding 97- to 99-Kilodalton Outer Membrane Proteins of Chlamydia pneumoniae

1999 ◽  
Vol 67 (1) ◽  
pp. 375-383 ◽  
Author(s):  
Katrine Knudsen ◽  
Anna Sofie Madsen ◽  
Per Mygind ◽  
Gunna Christiansen ◽  
Svend Birkelund
Keyword(s):  
Membrane Proteins ◽  
Outer Membrane ◽  
Chlamydia Pneumoniae ◽  
Outer Membrane Proteins ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Amino Acid Sequences ◽  
Chlamydia Psittaci ◽  
Membrane Complex ◽  
Genes Encoding

ABSTRACT Two genes encoding 97- to 99-kDa Chlamydia pneumoniaeVR1310 outer membrane proteins (Omp4 and Omp5) with mutual similarity were cloned and sequenced. The proteins were shown to be constituents of the C. pneumoniae outer membrane complex, and the deduced amino acid sequences were similar to those of putative outer membrane proteins encoded by the Chlamydia psittaci andChlamydia trachomatis gene families. By use of a monospecific polyclonal antibody against purified recombinant Omp4, it was shown that without heating, the protein migrated at 65 to 75 kDa in sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Immunoelectron microscopy showed that epitopes of Omp4 were exposed on the surface of C. pneumoniae elementary bodies, reticulate bodies, and outer membrane complex. Proteins encoded by the C. pneumoniae gene family seem to be dominant antigens in experimentally infected mice.

scholarly journals Identification of Chlamydia trachomatis Outer Membrane Complex Proteins by Differential Proteomics

2010 ◽  
Vol 192 (11) ◽  
pp. 2852-2860 ◽  
Author(s):  
Xiaoyun Liu ◽  
Mary Afrane ◽  
David E. Clemmer ◽  
Guangming Zhong ◽  
David E. Nelson
Keyword(s):  
Mass Spectrometry ◽  
Chlamydia Trachomatis ◽  
Outer Membrane ◽  
Secretion Systems ◽  
Differential Proteomics ◽  
Infectious Particle ◽  
Novel Proteins ◽  
Membrane Complex ◽  
Associated Proteins ◽  
Protein Secretion Systems

ABSTRACT The extracellular chlamydial infectious particle, or elementary body (EB), is enveloped by an intra- and intermolecular cysteine cross-linked protein shell called the chlamydial outer membrane complex (COMC). A few abundant proteins, including the major outer membrane protein and cysteine-rich proteins (OmcA and OmcB), constitute the overwhelming majority of COMC proteins. The identification of less-abundant COMC proteins has been complicated by limitations of proteomic methodologies and the contamination of COMC fractions with abundant EB proteins. Here, we used parallel liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS) analyses of Chlamydia trachomatis serovar L2 434/Bu EB, COMC, and Sarkosyl-soluble EB fractions to identify proteins enriched or depleted from COMC. All well-described COMC proteins were specifically enriched in the COMC fraction. In contrast, multiple COMC-associated proteins found in previous studies were strongly enriched in the Sarkosyl-soluble fraction, suggesting that these proteins are not COMC components or are not stably associated with COMC. Importantly, we also identified novel proteins enriched in COMC. The list of COMC proteins identified in this study has provided reliable information for further understanding chlamydial protein secretion systems and modeling COMC and EB structures.

scholarly journals The serological classification of Neisseria gonorrhoeae. I. Isolation of the outer membrane complex responsible for serotypic specificity.

1976 ◽  
Vol 143 (4) ◽  
pp. 741-758 ◽  
Author(s):  
K H Johnston ◽  
K K Holmes ◽  
E C Gotschlich
Keyword(s):  
Neisseria Gonorrhoeae ◽  
Outer Membrane ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Molecular Size ◽  
Antigenic Specificity ◽  
Membrane Complex ◽  
Sds Page ◽  
Gonococcal Strain

Neisseria gonorrhoeae has been subdivided into several classes of serological distinct groups. The serotyping system is based upon the antigenic specificity of a protein serotype antigen. This protein is the major polypeptide of the outer membrane of the gonococcus and accounts for over 60% of that membrane's total protein. The serotype antigen complex was isolated by mild extraction of intact organisms in 200 mM lithium acetate buffer, pH 6.0 with 10 mM EDTA for 2 h at 45 degrees C. The extract was fractionated on Sepharose 6B and partially purified by precipitation at pH 4.2 by addition of 10% (vol/vol) acetic acid. Each serotype antigen has a unique subunit molecular size as determined by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). Preliminary typing of a gonococcal strain may be performed by comparative SDA-PAGE. To date, 16 different serotypes, representing a diverse distribution, have been isolated.

scholarly journals Structure-Function Analysis of BfpB, a Secretin-Like Protein Encoded by the Bundle-Forming-Pilus Operon of EnteropathogenicEscherichia coli

2001 ◽  
Vol 183 (16) ◽  
pp. 4848-4859 ◽  
Author(s):  
Sarah A. Schmidt ◽  
David Bieber ◽  
Sandra W. Ramer ◽  
Jaiweon Hwang ◽  
Cheng-Yen Wu ◽  
...  
Keyword(s):  
Outer Membrane ◽  
Function Analysis ◽  
Sodium Dodecyl ◽  
Functional Studies ◽  
Membrane Complex ◽  
Type Iv ◽  
Outer Membrane Lipoprotein ◽  
Multimeric Complex ◽  
Pilus Biogenesis ◽  
Gated Channel

ABSTRACT Production of type IV bundle-forming pili by enteropathogenicEscherichia coli (EPEC) requires BfpB, an outer-membrane lipoprotein and member of the secretin protein superfamily. BfpB was found to compose a ring-shaped, high-molecular-weight outer-membrane complex that is stable in 4% sodium dodecyl sulfate at temperatures of ≤65°C. Chemical cross-linking and immunoprecipitation experiments disclosed that the BfpB multimeric complex interacts with BfpG, and mutational studies showed that BfpG is required for the formation and/or stability of the multimer but not for the outer-membrane localization of BfpB. Formation of the BfpB multimer also does not require BfpA, the repeating subunit of the pilus filament. Functional studies of the BfpB-BfpG complex revealed that its presence confers vancomycin sensitivity, indicating that it may form an incompletely gated channel through the outer membrane. BfpB expression is also associated with accumulation of EPEC proteins in growth medium, suggesting that it may support both pilus biogenesis and protein secretion.

scholarly journals Proteomic and Immunoblot Analyses of Bartonella quintana Total Membrane Proteins Identify Antigens Recognized by Sera from Infected Patients

2007 ◽  
Vol 75 (5) ◽  
pp. 2548-2561 ◽  
Author(s):  
Jenni K. Boonjakuakul ◽  
Helen L. Gerns ◽  
Yu-Ting Chen ◽  
Linda D. Hicks ◽  
Michael F. Minnick ◽  
...  
Keyword(s):  
Membrane Proteins ◽  
Outer Membrane ◽  
Outer Membrane Proteins ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Two Dimensional ◽  
Human Immune System ◽  
Bartonella Quintana ◽  
Peptide Mass ◽  
Total Membrane

ABSTRACT Bartonella quintana is a fastidious, gram-negative, rod-shaped bacterium that causes prolonged bacteremia in immunocompetent humans and severe infections in immunocompromised individuals. We sought to define the outer membrane subproteome of B. quintana in order to obtain insight into the biology and pathogenesis of this emerging pathogen and to identify the predominant B. quintana antigens targeted by the human immune system during infection. We isolated the total membrane proteins of B. quintana and identified 60 proteins by two-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis and peptide mass fingerprinting. Using the newly constructed proteome map, we then utilized two-dimensional immunoblotting with sera from 21 B. quintana-infected patients to identify 24 consistently recognized, immunoreactive B. quintana antigens that have potential relevance for pathogenesis and diagnosis. Among the outer membrane proteins, the variably expressed outer membrane protein adhesins (VompA and VompB), peptidyl-prolyl cis-trans-isomerase (PpI), and hemin-binding protein E (HbpE) were recognized most frequently by sera from patients, which is consistent with surface expression of these virulence factors during human infection.

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