Fig. 4: PUL structures and protein abundance of the most abundant TonB-dependent transporters in metaproteomic samples, for each polysaccharide substrate class where substrate could be assigned.

PUL gene arrangements were taken from individual MAGs where they were clearest, which in most cases were not the species representative MAG. The top-most TBDT, Ga0206129_100259162, is part of a ‘tandem-PUL’ structure, with two susCD-like genes between the two pairs of alginate specific polysaccharide lyases.