Definition of the phage G13 receptor as structural domains of trisaccharides in Salmonella and Escherichia coli core oligosaccharides

Abstract

The interaction between phage G13 and different bacterial and synthetic oligosaccharides has been studied using equilibrium dialysis inhibition. The results, and conformational analysis of the oligosaccharides, make us conclude that the phage G13 carbohydrate receptor is a conformational domain involving three sugar residues. The following trisaccharide elements contain the domain: alpha-D-Galp-(1----3)-[alpha-D-Galp-(1----6)]-alpha-D-Glcp, alpha-D-Manp-(1----3)-[alpha-D-Manp-(1----6)-alpha-D-Manp , and alpha-D-Glcp-(1----3)-[L-gly-alpha-D-man-Hepp-(1----7)]-L-gly-alph a-D- man-Hepp. Thus two structures, either a hexose substituted with alpha-D-glycopyranosyl groups in the 3- and 6-positions, or a heptose substituted with such groups in the 3- and 7-positions are functional G13 binding sites. Such domains are present in several cores of lipopolysaccharides from Salmonella and Escherichia coli species. Some cores, e.g. those from S. typhimurium chemotypes Ra, Rb1 and Rb2, contain two such domains. The identification of two G13 receptor domains within different core saccharides could explain the broad host range of this phage.

Interaction between phage G13 and its oligosaccharide receptor studied by equilibrium dialysis

“…The binding to the Rb2 and Rc saccharides suggests an important role of the inner hexose, and possibly heptose, region(s). In the two accompanying publications calculations of the conformation of different core saccharides and additional inhibition experiments using synthetic oligosaccharides have been performed Wollin et al, 1989). The studies result in a topographical model suggesting a trisaccharide of the core as the phage receptor domain.…”