Isolation and characterization of a bacteriophage polysaccharide

Abstract

A high molecular weight heteropolysaccharide, composed of glucose, glucuronic acid, N-acetylglucosamine, and mannose in an approximate molar ratio of 1:2:2:5, respectively, was isolated from phage K-2 and from the soluble fraction of phage-infected Aerobacter aerogenes lysates. Treatment of pure phage with 8 M urea at 4 degrees quantitatively solubilizes the bound polysaccharide and capsular polysaccharide (Yurewicz, E.C., Ghalambor, M.A., Duckworth, D.H., and Heath, E.C. (1971) J. Biol. Chem. 246, 5607-5616) with the release of only traces of other phage constituents; on this basis, it was concluded that the polysaccharide, like the the glycanohydrolase, is externally localized in the phage structure. Phage polysaccharide and glycanohydrolase fractionate similarly on ion exchange resins and gel electrophoresis in sodium dodecyl sulfate, but each may be purified to homogeneity by the procedures employed. The biosynthesis of the polysaccharide was shown to be uniquely dependent upon phage K-2 infection by: (a) absence of the polysaccharide in cells, the culture filtrate, or sonicated extracts of uninfected cells; (b) kinetics of polysaccharide synthesis following phage infection; and (c) isotopic double-labeling experiments that demonstrated the synthesis of polysaccharide only after initiation of phage replication in infected cells.