The ecological distribution of PULs in nature. PULs are found in a variety of microbial communities, highlighting the global role of this polysaccharide utilization strategy. Each semitransparent box contains a representative bacterial PUL from a distinct microbial ecosystem, as well as the schematic structure of the target glycan. Clockwise from the top left are the arabinan PUL from an unidentified bacterium from the gut of Pseudocanthotermes
militaris (93), the xylan PUL from Prevotella
bryantii (97), the laminarin PUL from Gramella
forsetii (101), the xyloglucan PUL from Bacteroides ovatus (78), the chitin PUL from Flavobacterium
johnsoniae (112), and the xyloglucan PUL from Cellvibrio
japonicus (126). Genes are colored according to protein function as follows: blue, endo-GH; cyan, exo-GH; orange, SusD-homologous SGBP; yellow, other SGBP; purple, TBDT; pink, (hybrid) two-component sensor (HTCS/TCS); gray, unknown or other function (est, esterase; transp, transporter; deam, deaminase). Monosaccharides are represented by Consortium for Functional Glycomics symbols (154).