Figure 2. Structure features.

(A) The β-sandwich domain (in blue) is indispensable for XylC, because Trp¹¹³ in the loop is important for substrate binding by providing stacking interaction with the xylose unit at the subsite −1. (B) XylC has the longest asparagine ladder (nine asparagine residues) of all asparagine ladders observed from parallel β-helix structures solved to date.