Salmonella bacteriophage glycanases: endorhamnosidase activity of bacteriophages P27, 9NA, and KB1.

Four bacteriophages, P22, P27, 9NA, and KB1, active on smooth Salmonella strains belonging to serogroups A, B, and D1 were investigated for endoglycosidase activity and specificity in enzyme hydrolysis assays. Purified phage was incubated with phenol-water-extracted lipopolysaccharide preparations which had been partially delipidated. Dialyzable oligosaccharides, released by phage glycosidase activity, were analyzed by sugar and methylation analyses. Phages P27, 9NA, and KB1, as well as P22 assayed earlier (U. Eriksson et al., J. Gen. Virol. 43: 503-511, 1979; S. Iwashita and S. Kanegasaki, Biochem. Biophys. Res. Commun. 55:403-409, 1973), were all found to have phage-associated endorhamnosidase activity hydrolyzing the O-polysaccharide chain common to bacteria of serogroups A, B, and D1 [Formula: see text] between the l-rhamnose and d-galactose residues. The nature of the R monosaccharide, abequose, tyvelose, or paratose, had no effect on the activity or specificity of the endorhamnosidase, whereas a change of the d-galactose --> d-mannose linkage from alpha1,2 to alpha1,6 made the O-polysaccharide chain resistant to the endorhamnosidases. Modification of the O chain by glucosylation of the d-galactose residue at O-4 or O-6 revealed two glycosidase specificities: the phage P22 and P27 enzymes hydrolyzed O chains glucosylated at O-4 but not O-6, whereas the phage 9NA and KB1 enzymes hydrolyzed chains glucosylated at O-6 but not O-4. Phage KB1, like P22 and P27, had a short, noncontractile tail containing a base plate with tail spikes (morphologically Bradley group C), whereas 9NA had a long, flexible tail ending with a base plate-like appendage (Bradley group B), which suggests that the endorhamnosidase activity can be associated with different tail structures.