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Chlamydia trachomatis Mip-like protein
A G Lundemose1, D A Rouch, S Birkelund
1Institute of Medical Microbiology, University of Aarhus, Denmark.
Abstract:
A 27 kDa Chlamydia trachomatis Mip-like protein with homology of a 175-amino-acid C-terminal fragment to the surface-exposed Legionella pneumophila mip-gene product has previously been described. In this paper the entire chlamydia Mip-like sequence of C. trachomatis serovar L2 (lymphogranuloma venereum (LGV) biovar) is presented. The sequence shows high similarity to the legionella Mip protein and its C-terminal region, like that of the legionella Mip, has high amino acid similarity to eukaryotic and prokaryotic FK506-binding proteins. The chlamydial mip-like gene was detected by polymerase chain reaction (PCR) in other C. trachomatis serovars and by sequencing of the mip-like genes of serovars B and E (trachoma biovar) was shown to be highly conserved within the two major biovars of C. trachomatis. Monoclonal and polyclonal antibodies raised against the recombinant Mip-like protein failed to demonstrate surface-exposed epitopes on infectious elementary bodies or reproductive reticulate body forms either by immunofluorescence or immuno-gold electron microscopy. However, a complement-dependent inhibition of up to 91% of infectivity for cell cultures was observed with antibodies to the N-terminal fragment of the Mip-like protein suggesting that antibody-accessible epitopes are present on infectious EBs.
Insights
Chlamydia trachomatis possesses a Mip-like protein conserved across serovars. Antibodies targeting its N-terminal fragment inhibit chlamydial infectivity, indicating accessible epitopes on infectious elementary bodies.
Area of Science:
- Microbiology
- Immunology
- Molecular Biology
Background:
- Chlamydia trachomatis is a significant human pathogen.
- A Mip-like protein in C. trachomatis shares homology with Legionella pneumophila Mip.
- This protein resembles eukaryotic and prokaryotic FK506-binding proteins.
Purpose of the Study:
- To present the full sequence of the C. trachomatis Mip-like protein.
- To investigate the conservation of the chlamydial Mip-like gene.
- To determine the surface exposure of Mip-like protein epitopes and their role in infectivity.
Main Methods:
- DNA sequencing of the Mip-like gene from C. trachomatis serovar L2.
- Polymerase chain reaction (PCR) to detect the gene in other serovars.
- Antibody production and immunofluorescence/immuno-gold electron microscopy to assess epitope accessibility.
- Complement-dependent infectivity inhibition assays.
Main Results:
- The complete Mip-like sequence of C. trachomatis serovar L2 was determined.
- The chlamydial mip-like gene is highly conserved across major C. trachomatis biovars.
- Antibodies against the recombinant Mip-like protein did not detect surface-exposed epitopes on elementary bodies or reticulate bodies.
- Antibodies against the N-terminal fragment inhibited up to 91% of cell culture infectivity.
Conclusions:
- The C. trachomatis Mip-like protein is conserved and shares similarities with known FK506-binding proteins.
- Antibody-accessible epitopes are present on the N-terminus of the Mip-like protein on infectious elementary bodies.
- These findings suggest a potential role for the N-terminal region in chlamydial infectivity and host interaction.