Purification and characterization of a Salmonella typhimurium agglutinin from gut mucus secretions

Abstract

One of the earliest events in Salmonella typhimurium pathogenesis seems to be the interaction of the bacterium with the mucus of the gut. After exposing S. typhimurium to guinea-pig colon, we were able to demonstrate by electron microscopy that S. typhimurium bacteria were trapped on, or in, the mucus layer. Specific components isolated from crude mucus secretions were found to aggregate the bacteria. The degree of bacterial aggregation was dependent on the protein concentration of the crude mucus and on time. Aggregation of S. typhimurium could be abolished by sugars: L-fucose exhibited the strongest inhibition, followed by D-glucose, D-galactose and D-mannose. Lectins were also capable of inhibiting aggregation, the lectin of Ulex europaeus (UEA I), specific for L-fucose, was found to be a stronger inhibitor of bacterial aggregation than Con A. The agglutinin for S. typhimurium isolated from guinea-pig colonic crude mucus preparation was characterized as a 15 kDa glycoprotein. An affinity-purified anti-15 kD antibody inhibited, dose-dependently, the aggregation of S. typhimurium by crude mucus material.