Chitinases degrade chitin, one of the most widespread polysaccharides in nature, into low molecular weight chitooligomers (COS), which have a broad range of pharmaceutical and medicinal applications. We disclosed a detailed picture of the molecular events behind substrate/products binding in a fungal chitinase, giving full insight into its donor and acceptor subsites. Our crystallographic analysis revealed a previously unobserved dynamic on-off ligand binding process associated with motion of its insertion CID domain. This might represent a molecular mechanism complementary to the crucial role ascribed to aromatics at the catalytic site in processivity, which is an essential property modulating the bioconversion of chitin. Furthermore, our analysis elucidates the implication of some highly flexible residues in activity and suggested new targets to address engineering of these biotechnologically important enzymes.
Ref.: “Structural inspection and protein motions modelling of a fungal glycoside hydrolase family 18 chitinase by crystallography depicts dynamic enzymatic mechanism”. E. Jiménez-Ortega, P.E. Kidibule, M. Fernández-Lobato, J. Sanz-Aparicio. Computational and Structural Biotechnology Journal 19, 5466-5478 (2021) http://doi.org/10.1016/j.csbj.2021.09.027
