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Forward Genetic Approaches in Chlamydia trachomatis
Published on: October 23, 2013
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The Chlamydia trachomatis PmpD adhesin forms higher order structures through disulphide-mediated covalent
Wayne Paes1,2, Adam Dowle3, Jamie Coldwell1
1York Structural Biology Laboratory, University of York, York, United Kingdom.
Plos One
|June 19, 2018
Summary
Chlamydia trachomatis polymorphic membrane protein D (PmpD) uses disulfide bonds for structure and self-assembly. This protein fragment also acts as an adhesin, potentially contributing to chlamydial infections.
Area of Science:
- Microbiology
- Structural Biology
- Immunology
Background:
- Chlamydia trachomatis (Ct) is a major bacterial pathogen causing sexually transmitted infections and infectious blindness.
- The polymorphic membrane protein D (PmpD) of Ct is a target for protective immunity, but its structure and function are poorly understood.
- Understanding PmpD assembly and structure-function is crucial for developing effective vaccines and treatments.
Purpose of the Study:
- To biophysically analyze the immunogenic passenger domain of recombinant PmpD (rPmpD).
- To elucidate the role of disulfide bonds in PmpD structure, oligomerization, and function.
- To investigate the adhesive properties of rPmpD and its potential role in Chlamydia pathogenesis.
Main Methods:
- Differential cysteine labeling coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS) was used to analyze disulfide bonds.
- Circular dichroism spectroscopy was employed to study protein secondary structure.
- Cell-binding assays were performed to assess the adhesin-like properties of rPmpD.
Main Results:
- Widespread intra- and intermolecular disulfide interactions stabilize the monomeric structure and promote oligomerization of rPmpD.
- Oligomeric and monomeric rPmpD adopt beta-sheet folds, characteristic of Gram-negative bacterial type V secretion systems (T5SSs).
- rPmpD exhibits adhesin-like properties, inhibiting the binding of rPmpD-coated beads to mammalian cells.
Conclusions:
- Disulfide bonds are critical for the structural integrity and self-association of chlamydial PmpD.
- PmpD functions as an adhesin, contributing to bacterial virulence and pathogenesis.
- These findings reveal a potential mechanism of self-association for bacterial T5SS virulence factors unique to Chlamydiaceae.
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