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 binding protein involved in a host of processes including inflammation, regulation of neuroendocrine signaling, apoptosis and membrane trafficking. Annexin A1 binding to glycans has been implicated in cell attachment and modulation of annexin A1 function. We characterized in detail the glycan binding preferences of annexin A1 using glycan arrays and surface plasmon resonance as a starting point to understand the role of glycan binding in annexin A1 function. Glycan array analysis identified a series of sulfated oligosaccharides, demonstrating for the first time annexin A1 binding to sulfated non-glycosaminoglycan carbohydrates. Using heparin/heparan sulfate microarrays, highly sulfated heparan sulfate/heparin were identified as preferential ligands of annexin A1. Binding of annexin A1 to heparin/heparan sulfate is calcium, but not magnesium dependent. The structure-activity relationship of annexin A1-heparan sulfate interactions were established in detail using chemically defined sugars and novel methods, being the first characterization of a calcium dependent heparin binding protein with such approach. N-sulfation and 2-O-sulfation were identified as particularly important for binding.