FIGURE 1.

Function and phylogeny of PL2s. A, β-elimination reaction coordinate resulting in a 4,5-unsaturated product. The dashed semicircles indicate subsites in the positive (toward the reducing end) and negative (toward the non-reducing end) of the scissile bond. B, schematic of exolytic and endolytic modes of activity on HG. Exolytic enzymes digest HG strictly from the terminus of the polysaccharide and release a single defined product. Endolytic enzymes cleave internal glycosidic linkages to generate a mixed product profile. C, representative unrooted tree highlighting the phylogeny of subfamily 1 and 2 members discussed in this study. Boundaries identified by CAZy are indicated with dashed circles. The associated modes of activity are represented with endolytic and exolytic models. The presumed transitional sequence space between these activities is shown with a black triangle. Ye, Y. enterocoliticus; Dd, D. dadantii; Pa, P. atrosepticum; Pae, Paenibacillus sp.