Molecular characterization of a family 5 glycoside hydrolase suggests an induced-fit enzymatic mechanism. Marcelo V. Liberato et al (2016), Scientific Reports http://dx.doi.org/10.1038/srep23473 Glycoside hydrolases (GHs) play fundamental roles in the decomposition of lignocellulosic biomaterials. Here, we report the full-length structure of a cellulase from Bacillus licheniformis (BlCel5B), a member of the GH5 subfamily 4 that is entirely dependent on its two ancillary modules (Ig-like module and CBM46) for catalytic activity. Using X-ray crystallography, small-angle X-ray scattering and molecular dynamics simulations, we propose that the C-terminal CBM46 caps the distal N-terminal catalytic domain (CD) to establish a fully functional active site via a combination of large-scale multidomain conformational selection and induced-fit mechanisms. The Ig-like module is pivoting the packing and unpacking motions of CBM46 relative to CD in the assembly of the binding subsite. This is the first example of a multidomain GH relying on large amplitude motions of the CBM46 for assembly of the catalytically competent form of the enzyme. Good channel: https://www.youtube.com/Dlium Subscribe, like and comment. Good website: https://www.dlium.com Bookmark, subscribe and comment.

• published: 02 Apr 2016
• views: 259