Discovery of processive catalysis by an exo-hydrolase with a pocket-shaped active site

Substrates associate and products dissociate from enzyme catalytic sites rapidly, which hampers investigations of their trajectories. The high-resolution structure of the native Hordeum exo-hydrolase HvExoI isolated from seedlings reveals that non-covalently trapped glucose forms a stable enzyme-product complex. Here, we report that the alkyl β-d-glucoside and methyl 6-thio-β-gentiobioside substrate analogues perfused in crystalline HvExoI bind across the catalytic site after they displace glucose, while methyl 2-thio-β-sophoroside attaches nearby. Structural analyses and multi-scale molecular modelling of nanoscale reactant movements in HvExoI reveal that upon productive binding of incoming substrates, the glucose product modifies its binding patterns and evokes the formation of a transient lateral cavity, which serves as a conduit for glucose departure to allow for the next catalytic round. This path enables substrate-product assisted processive catalysis through multiple hydrolytic events without HvExoI losing contact with oligo- or polymeric substrates. We anticipate that such enzyme plasticity could be prevalent among exo-hydrolases. © 2019, Crown.

item.page.dc.description

Indexación: Scopu

Keywords

Biocatalysis, Catalytic Domain, Crystallography, X-Ray, Enzyme Assays, Glucosidases, Glycosides, Hordeum, Models, Molecular, Molecular Dynamics Simulation, Nuclear Magnetic Resonance, Biomolecular, Plant Proteins, Recombinant Proteins, Seedlings, Substrate Specificity

Citation

Nature Communications Volume 10, Issue 11 December 2019 Article number 2222

DOI

10.1038/s41467-019-09691-z

URI

http://repositorio.unab.cl/xmlui/handle/ria/20270

Collections

FCE - Artículos de Revista

Full item page