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Publication Abstract from PubMed

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 beta-D-glucoside and methyl 6-thio-beta-gentiobioside substrate analogues perfused in crystalline HvExoI bind across the catalytic site after they displace glucose, while methyl 2-thio-beta-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.

Discovery of processive catalysis by an exo-hydrolase with a pocket-shaped active site.,Streltsov VA, Luang S, Peisley A, Varghese JN, Ketudat Cairns JR, Fort S, Hijnen M, Tvaroska I, Arda A, Jimenez-Barbero J, Alfonso-Prieto M, Rovira C, Mendoza F, Tiessler-Sala L, Sanchez-Aparicio JE, Rodriguez-Guerra J, Lluch JM, Marechal JD, Masgrau L, Hrmova M Nat Commun. 2019 May 20;10(1):2222. doi: 10.1038/s41467-019-09691-z. PMID:31110237^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.