Related Experiment Videos
Genomic approach for analysis of surface proteins in Chlamydia pneumoniae
Silvia Montigiani1, Fabiana Falugi, Maria Scarselli
1Chiron SpA, 53100 Siena. Sezione di Microbiologia DMCSS, University of Bologna, 40138 Bologna, Italy.
Abstract:
Chlamydia pneumoniae, a human pathogen causing respiratory infections and probably contributing to the development of atherosclerosis and heart disease, is an obligate intracellular parasite which for replication needs to productively interact with and enter human cells. Because of the intrinsic difficulty in working with C. pneumoniae and in the absence of reliable tools for its genetic manipulation, the molecular definition of the chlamydial cell surface is still limited, thus leaving the mechanisms of chlamydial entry largely unknown. In an effort to define the surface protein organization of C. pneumoniae, we have adopted a combined genomic-proteomic approach based on (i) in silico prediction from the available genome sequences of peripherally located proteins, (ii) heterologous expression and purification of selected proteins, (iii) production of mouse immune sera against the recombinant proteins to be used in Western blotting and fluorescence-activated cell sorter (FACS) analyses for the identification of surface antigens, and (iv) mass spectrometry analysis of two-dimensional electrophoresis (2DE) maps of chlamydial protein extracts to confirm the presence of the FACS-positive antigens in the chlamydial cell. Of the 53 FACS-positive sera, 41 recognized a protein species with the expected size on Western blots, and 28 of the 53 antigens shown to be surface-exposed by FACS were identified on 2DE maps of elementary-body extracts. This work represents the first systematic attempt to define surface protein organization in C. pneumoniae.
Insights
Researchers identified surface proteins of Chlamydia pneumoniae, a bacterium causing respiratory illness and heart disease. This study advances understanding of bacterial cell surface organization and host cell entry mechanisms.
Area of Science:
- Microbiology
- Cell Biology
- Infectious Diseases
Background:
- Chlamydia pneumoniae is a human pathogen responsible for respiratory infections and potentially atherosclerosis.
- Understanding its cell surface is crucial for defining host cell entry mechanisms, but is limited by genetic manipulation challenges.
Purpose of the Study:
- To systematically define the surface protein organization of Chlamydia pneumoniae.
- To identify surface-exposed antigens for a better understanding of bacterial-host interactions.
Main Methods:
- A combined genomic-proteomic approach was used, including in silico prediction, heterologous protein expression, antibody production, FACS analysis, and mass spectrometry.
- Proteins predicted to be surface-located were expressed and purified.
- Antibodies generated against these proteins were used for FACS analysis to identify surface antigens.
- Mass spectrometry of 2DE maps confirmed the presence of identified antigens on elementary bodies.
Main Results:
- 53 antigens were identified as surface-exposed using FACS analysis.
- 41 of these recognized proteins of the expected size on Western blots.
- 28 of the 53 surface-exposed antigens were identified on 2DE maps of elementary body extracts.
Conclusions:
- This study provides the first systematic definition of the Chlamydia pneumoniae cell surface proteome.
- The identified surface proteins are potential targets for understanding and combating C. pneumoniae infections.