A refined model for the TSG-6 link module in complex with hyaluronan: use of defined oligosaccharides to probe structure and function

Higman, V. A. et al. (2014) A refined model for the TSG-6 link module in complex with hyaluronan: use of defined oligosaccharides to probe structure and function. Journal of Biological Chemistry, 289(9), pp. 5619-5634. (doi: 10.1074/jbc.M113.542357) (PMID:24403066) (PMCID:PMC3937638)

Abstract

Tumor necrosis factor-stimulated gene-6 (TSG-6) is an inflammation-associated hyaluronan (HA)-binding protein that contributes to remodeling of HA-rich extracellular matrices during inflammatory processes and ovulation. The HA-binding domain of TSG-6 consists solely of a Link module, making it a prototypical member of the superfamily of proteins that interacts with this high molecular weight polysaccharide composed of repeating disaccharides of D-glucuronic acid and N-acetyl-D-glucosamine (GlcNAc). Previously we modeled a complex of the TSG-6 Link module in association with an HA octasaccharide based on the structure of the domain in its HA-bound conformation. Here we have generated a refined model for a HA/Link module complex using novel restraints identified from NMR spectroscopy of the protein in the presence of 10 distinct HA oligosaccharides (from 4- to 8-mers); the model was then tested using unique sugar reagents, i.e. chondroitin/HA hybrid oligomers and an octasaccharide in which a single sugar ring was 13C-labeled. The HA chain was found to make more extensive contacts with the TSG-6 surface than thought previously, such that a D-glucuronic acid ring makes stacking and ionic interactions with a histidine and lysine, respectively. Importantly, this causes the HA to bend around two faces of the Link module (resembling the way that HA binds to CD44), potentially providing a mechanism for how TSG-6 can reorganize HA during inflammation. However, the HA-binding site defined here may not play a role in TSG-6-mediated transfer of heavy chains from inter-α-inhibitor onto HA, a process known to be essential for ovulation.

• Item Type: Articles
• Additional Information: This work was supported by Arthritis Research UK Grants 16539, 18472, and 19489 and Medical Research Council Grant G0701180.
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Dyer, Dr Douglas
• Authors: Higman, V. A., Briggs, D. C., Mahoney, D. J., Blundell, C. D., Sattelle, B. M., Dyer, D. P., Green, D. E., DeAngelis, P. L., Almond, A., Milner, C. M., and Day, A. J.
• College/School: College of Medical Veterinary and Life Sciences > School of Infection & Immunity
• Journal Name: Journal of Biological Chemistry
• Publisher: American Society for Biochemistry and Molecular Biology
• ISSN: 0021-9258
• ISSN (Online): 1083-351X