Figure 2.

Glucuronate bound to OtCE15A. Binding of glucuronate to the WT OtCE15A (A; PDB code 6SYR) and S267A OtCE15A variant (C; showing both anomers of the carbohydrate; PDB code 6SYV) is similar to that of the methyl ester of 4-O-methyl glucuoronoate determined in the structure of StGE2 from T. thermophila (B; previously S. thermophile; PDB code 4G4G with the ligand taken from 4G4J by structural alignment). Notably, the side chain of the conserved active-site arginine is found rotated toward, and interacts with, the glucuronate molecule in the OtCE15A product ligated structures differently than in the StGE2 substrate ligated structure.