Characterization of Annexin A1 Glycan Binding Reveals Binding to Highly Sulfated Glycans with Preference for Highly Sulfated Heparan Sulfate and Heparin

摘要

Annexin A1 is a multifunctional, calcium-dependent phospholipid bindingnprotein involved in a host of processes including inflammation, regulation of neuroendo-ncrine signaling, apoptosis, andmembrane trafficking. Binding of annexin A1 to glycans hasnbeen implicated in cell attachment and modulation of annexin A1 function. A detailedncharacterization of the glycan binding preferences of annexin A1 using carbohydratenmicroarrays and surface plasmon resonance served as a starting point to understand thenrole of glycan binding in annexin A1 function. Glycan array analysis identified annexin A1nbinding to a series of sulfated oligosaccharides and revealed for the first time that annexinnA1 binds to sulfated non-glycosaminoglycan carbohydrates. Using heparin/heparannsulfate microarrays, highly sulfated heparan sulfate/heparin were identified as preferrednligands of annexin A1. Binding of annexin A1 to heparin/heparan sulfate is calcium- butnnot magnesium-dependent. An in-depth structure-activity relationship of annexin A1-nheparan sulfate interactions was established using chemically defined sugars. For the firstntime, a calcium-dependent heparin binding protein was characterized with such an approach. N-Sulfation and 2-O-sulfation werenidentified as particularly important for binding.