Non-covalently bound to the neck of the phage capsid and mediating attachment of the viral particle to host cell-surface polysaccharide. It displays endorhamnosidase enzymatic activity, hydrolyzing the alpha-1,3-O-glycosidic linkage between rhamnose and galactose of the O-antigen polysaccharide. Optimum pH is 7.5. Homotrimer. The active site involves residues located on two different subunits. Belongs to the P22likevirus tail fiber protein family.