High-affinity binding of laminin by Helicobacter pylori: Evidence for a lectin-like interaction

Abstract Laminin, the major glycoprotein of basement membranes, was shown to be bound by the human gastric pathogen Helicobacter pylori . Binding of ¹²⁵I-laminin by strain 17874 was time-dependent, specific and saturable. Scatchard analysis of specific binding indicated about 2000 binding sites per cell with a dissociation constant of 8.5 pM. Treatment of the cells by heat (80°) and with proteolytic enzymes drastically reduced laminin binding, suggesting that the laminin receptors are surface proteins. Some highly glycosylated glycoproteins inhibited laminin binding by 50%. Furthermore, N -acetylneuraminyllactose decreased laminin binding by 70% and neuraminidase treatment of laminin by 50%, while a recombinant B1 chain of laminin, containing high-mannose type oligosaccharides, inhibited binding by only 25%. This suggests that terminal sialic acids on laminin compete for a specific sugar binding protein(s) on H. pylori cells.