Introduction of Selectin-like Binding Specificity into a Homologous Mannose-binding Protein

Olivier Blanck,Susanne T Iobst,Christopher Gabel,Kurt Drickamer

doi:10.1074/jbc.271.13.7289

Olivier Blanck, Susanne T Iobst + Show 2 more

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https://doi.org/10.1074/jbc.271.13.7289

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Abstract

The structures of the ligand-binding C-type carbohydrate-recognition domains of selectin cell adhesion molecules and of mannose-binding proteins (MBPs) are similar to each other even though these proteins bind very different carbohydrate ligands. Our current understanding of ligand binding by E-selectin is based on structural studies of unliganded E-selectin and of MBP-carbohydrate complexes, combined with results from mutagenesis of E-selectin. Five regions of E-selectin that differ in sequence from the corresponding regions of MBP have been introduced into the carbohydrate-recognition domain of MBP. Four of the changes have little effect on ligand binding. Insertion of one stretch of positively charged amino acids alters the sugar binding selectivity of the domain so that it now binds HL-60 cells and serum albumin derivatized with sialyl-Lewis X tetrasaccharide, thus mimicking the properties of E-selectin.

Highlights

Introduction ofSelectin-like Binding Specificity into a Homologous Mannose-binding Protein*(Received for publication, January 17, 1996, and in revised form, January 30, 1996)Olivier Blanck‡§, Susanne T
1 of the 5 amino acid side chains that ligate this Ca2ϩ differs between the two CRDs, the other 4 liganding amino acids are located at exactly corresponding positions in the two amino acid sequences (Fig. 2) and form sites with very similar geometry
Most of the amino acid side chains in mannose-binding proteins (MBPs)-A that form Ca2ϩ site 1 have been nonconservatively substituted in E-selectin so that this portion of the polypeptide is arranged in a substantially different way than in MBP-A

Summary

Introduction

Introduction ofSelectin-like Binding Specificity into a Homologous Mannose-binding Protein*(Received for publication, January 17, 1996, and in revised form, January 30, 1996)Olivier Blanck‡§, Susanne T. The fucose moiety of the ligand probably binds directly to the single Ca2ϩ and surrounding amino acid residues in the E-selectin CRD in a manner analogous to the interactions of mannose with Ca2ϩ site 2 of MBP-A [2] and of fucose and other sugars with Ca2ϩ site 2 of MBP-C [3], while negatively charged portions of the ligands are believed to interact with one or more regions of positive potential on adjacent portions of the CRD surface (16 –22).

Results

Conclusion