Deacetylation reaction catalyzed by Salmonella phage c341 and its baseplate parts

Phage c341 was shown to cleave off 14C-acetyl groups from a 14C-acetylated polysaccharide, prepared by the enzymatic acetylation of alkali-treated Salmonella anatum O-polysaccharide catalyzed by a membrane fraction from S. anatum (O-10 transacetylase). No deacetylation reaction was detected if the substate was prepared from alkali-treated O-polysaccharide of Salmonella newington. The structural difference of these O-polysaccharides is the anomeric configuration of the linkage between the common mannosyl-rhamnosyl-galactose repeating units. A soluble protein obtained from phage c341 lysate, which has previously been identified as the free form of the baseplate parts of this phage, showed the deacetylase activity, a result indicating that the baseplate is responsible for the enzymatic activity of the phage particles. These results suggest that as in the case of other Salmonella phages such as epsilon15, epsilon34, and P22 that contain glycosidases as baseplates, the baseplate deacetylase of c341 plays a role for phage adsorption through the formation of enzyme-substrate type complexes with the receptor O-polysaccharide.