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Structural requirements of heparin binding to Chlamydia trachomatis
J C Chen1, J P Zhang, R S Stephens
1Department of Laboratory Medicine, University of California, San Francisco 94143, USA.
The Journal of Biological Chemistry
|May 10, 1996
Summary
Heparin mimics Chlamydia trachomatis's attachment ligand, bridging bacteria to host cells. Specific molecular structures of heparin are crucial for this interaction, impacting infectivity.
Area of Science:
- Microbiology
- Biochemistry
- Molecular Biology
Background:
- Heparin acts as a functional analog for the Chlamydia trachomatis heparan sulfate-like attachment ligand.
- This ligand is essential for mediating infectivity by bridging chlamydiae to eukaryotic cells.
Purpose of the Study:
- To characterize the binding of heparin to the surface of Chlamydia organisms.
- To elucidate the structural requirements of the heparan sulfate-like ligand interactions for chlamydial infectivity.
Main Methods:
- Direct binding assays were used to characterize heparin binding to C. trachomatis.
- Competition assays with heparin-derived oligosaccharides and modified heparins were performed.
- Inhibition assays assessed the impact on chlamydial attachment and infection of host cells.
Main Results:
- Heparin binding was saturable for two C. trachomatis biovars, with trachoma biovar showing higher binding capacity.
- A decasaccharide was identified as the minimal chain length for effective binding, receptor competition, and infectivity rescue.
- N-desulfated, N-acetylated heparin competed for host cell receptors but not for chlamydial binding, indicating differential binding specificities.
Conclusions:
- The size and sulfation density of the heparan sulfate-like ligand are critical for binding and bridging chlamydiae to eukaryotic cells.
- Eukaryotic cell receptors and chlamydial surface acceptors exhibit distinct fine-structure requirements for ligand binding.