Glycosaminoglycans (GAGs) consist of repeating disaccharide units, comprising an amino sugar and an uronic acid. They are major components of extracellular matrices and cell surfaces in mammals. A variety of ligands interact with those negatively charged polysaccharides, but only few specific GAG-binding sequences are known, which are required for the different interactions [1]. We are developing GAG-binding decoys, which are mutant chemokines engineered towards higher GAG-binding affinity and with inactivated GPC receptor activity [2]. Our lead compound is a CXCL8-based decoy which is currently in clinical development for COPD.
It is therefore in the focus of our interest to localise GAG-binding sites on proteins such as chemokines. We have recently published a so-called GAG footprint by which we were able to localize the GAG-binding domain of CXCL11 [3]. Since the GAG footprint gives only a region of the GAG-binding protein which is protected by the GAG from proteolytic degradation, we have improved our method by introducing chemical cross-linking of the GAG and the protein into our method. By this means, we are able to identify the very specific amino acids which are responsible for the interaction of the protein with the GAG under investigation. Details of the method and first results on chemokine binding sites will be presented and will be related to the potential impact of GAG binding on the biological function of chemokines.
References:
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Essentials of Glycobiology. 2nd edition.Varki A, Cummings RD, Esko JD, et al., Cold Spring Harbor (NY):Cold Spring Harbor Laboratory Press; 2009.
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Adage T, Piccinini AM, Falsone A, Trinker M, Robinson J, Gesslbauer B, Kungl AJ. (2012) Br J Pharmacol. 167:1195-205.
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Severin IC, Gaudry JP, Johnson Z, Kungl A, Jansma A, Gesslbauer B, Mulloy B, Power C, Proudfoot AE, Handel T. (2010) J Biol Chem. 285:17713-24.
