Fig. 4: Interactions of BcsC with cellulose.

a Low-resolution cryo-EM maps of BcsC. Top panel: BcsC in the absence of cellotetraose with the full-length AlphaFold2-BcsC model (AF-P37650-F1) docked into the density. TPR#1 and #2 are colored green and lightblue, respectively, TPR#15–19 are colored as in (b) and (c) (TPR tetratricopeptide repeat). Bottom panel: BcsC in the presence of cellotetratose. The model of the refined C-terminal BcsC fragment is docked into the density with the putative ligand colored blue. b Close-up views of the putative cellulose binding sites of the refined maps in the absence (apo) and the presence of cellotetraose (shown as sticks colored cyan and red). Both maps are contoured at 10.5σ. c Surface representation of BcsC bound to the putative cellotetraose ligand.