Figure 4.

BlArap42B defines a novel GH42 α-l-arabinopyranosidase subfamily. The phylogenetic tree of GH42 enzymes, divides the family into the two distinct α-l-arabinopyranosidases (subfamily A) and β-galactosidases (subfamily G) subfamilies, respectively. Bifidobacterial GH42 enzymes (black) from the CAZy database reveals four distinct groups, with functional assignment for groups G2, G3, and G4. Group G1 was previously uncharacterized and multiple sequence alignment shows this group is diverse and comprises a unique Trp-X₁₂-Trp sequence motif as compared with the Phe-X₁₂-His sequence motif of groups G2, G3, and G4. Approximately 200 non-identical sequences (gray) found throughout the bacterial kingdom from each of the two Trp-X₁₂-Trp and Phe-X₁₂-His sequence motifs were merged with the bifidobacterial GH42 sequences and previously characterized GH42 enzymes (gray) to yield the phylogenetic tree.