Affinity and kinetics of sialyl Lewis-X and core-2 based oligosaccharides binding to L- and P-selectin.
Soluble oligosaccharide mimetics of natural selectin ligands act as competitive inhibitors of leukocyte adhesion in models of inflammation. We quantified the binding of simple oligosaccharides based on sialyl Lewis-X (sLe(X)) and complex molecules with the core-2 structure to L- and P-selectin, under both static and fluid flow conditions. Isolated human neutrophils were employed to mimic the physiological valency of selectins and selectin ligands. Surface plasmon resonance studies quantified binding kinetics. We observed the following: (i) The functional group at the anomeric position of carbohydrates plays an important role during selectin recognition, since sLe(X) and sialyl Lewis-a (sLe(a)) were approximately 5-7-fold poorer inhibitors of L-selectin mediated cell adhesion compared to their methyl glycosides. (ii) Despite their homology to physiological glycans, the putative carbohydrate epitopes of GlyCAM-1 and PSGL-1 bound selectins with low affinity comparable to that of sLe(X)-selectin interactions. Thus, besides the carbohydrate portion, the protein core of GlyCAM-1 or the presentation of carbohydrates in clusters on this glycoprotein may contribute to selectin recognition. (iii) A compound Galbeta1,4(Fucalpha1,3)GlcNAcbeta1,6(GalNAcbeta1,3)GalNAcalpha-OMe was identified which blocked L- and P-selectin binding at 30-100-fold lower doses than sLe(X). (iv) Surface plasmon resonance experiments determined that an sLe(X) analogue (TBC1269) competitively inhibited, via steric/allosteric mechanisms, the binding of two anti-P-selectin function blocking antibodies that recognized different epitopes of P-selectin. (v) TBC1269 bound P-selectin via both calcium-dependent and -independent mechanisms, with K(D) of approximately 111.4 microM. The measured on- and off-rates were high (k(off) > 3 s(-)(1), k(on) > 27,000 M(-)(1) s(-)(1)). Similar binding kinetics are expected for sLe(X)-selectin interactions. Taken together, our study provides new insight into the kinetics and mechanisms of carbohydrate interaction with selectins.
Department of Chemical and Biological Engineering, State University of New York, Buffalo, New York 14260, USA.
Mark E
ME
Beauharnois
Kevin C
KC
Lindquist
Dhananjay
D
Marathe
Peter
P
Vanderslice
Jie
J
Xia
Khushi L
KL
Matta
Sriram
S
Neelamegham
D000818:Animals; D001667:Binding, Competitive / Q000187:drug effects / Q000502:physiology; D001713:Biphenyl Compounds / Q000737:chemistry / Q000378:metabolism; D016466:CHO Cells; D002240:Carbohydrate Sequence; D002449:Cell Aggregation / Q000187:drug effects / Q000502:physiology; D006224:Cricetinae; D006801:Humans; D007700:Kinetics; D019041:L-Selectin / Q000235:genetics / Q000378:metabolism*; D007983:Lewis Blood Group Antigens / Q000737:chemistry* / Q000378:metabolism*; D008024:Ligands; D008358:Mannose / Q000031:analogs & derivatives; D008362:Mannosides / Q000737:chemistry / Q000378:metabolism; D008969:Molecular Sequence Data; D017351:N-Acetylglucosaminyltransferases / Q000737:chemistry / Q000378:metabolism; D009504:Neutrophils / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D009844:Oligosaccharides / Q000737:chemistry* / Q000378:metabolism*; D019007:P-Selectin / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding / Q000187:drug effects / Q000502:physiology; D011993:Recombinant Fusion Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D012212:Rheology; D000080506:Sialyl Lewis X Antigen; D020349:Surface Plasmon Resonance; D014312:Trisaccharides / Q000737:chemistry / Q000378:metabolism
D001713:Biphenyl Compounds; D007983:Lewis Blood Group Antigens; D008024:Ligands; D008362:Mannosides; D009844:Oligosaccharides; D019007:P-Selectin; D011993:Recombinant Fusion Proteins; D000080506:Sialyl Lewis X Antigen; D014312:Trisaccharides; D019041:L-Selectin; C073212:galactosyl beta(1-3)-N-acetylglucosaminyl-beta(1-6)-N-acetylgalactosamine; C108700:bimosiamose disodium; D017351:N-Acetylglucosaminyltransferases; C053024:beta-1,3-galactosyl-O-glycosyl-glycoprotein beta-1,6-acetylglucosaminyl transferase; D008358:Mannose