Crystal structures of the GH6Orpinomycessp. Y102 CelC7 enzyme with exo and endo activity and its complex with cellobiose

Abstract

The catalytic domain (residues 128–449) of theOrpinomycessp. Y102 CelC7 enzyme (OrpCelC7) exhibits cellobiohydrolase and cellotriohydrolase activities. Crystal structures ofOrpCelC7 and its cellobiose-bound complex have been solved at resolutions of 1.80 and 2.78 Å, respectively. Cellobiose occupies subsites +1 and +2 within the active site ofOrpCelC7 and forms hydrogen bonds to two key residues: Asp248 and Asp409. Furthermore, its substrate-binding sites have both tunnel-like and open-cleft conformations, suggesting that the glycoside hydrolase family 6 (GH6)OrpCelC7 enzyme may perform enzymatic hydrolysis in the same way as endoglucanases and cellobiohydrolases. LC-MS/MS analysis revealed cellobiose (major) and cellotriose (minor) to be the respective products of endo and exo activity of the GH6OrpCelC7.