Artículo
Discovery of processive catalysis by an exo-hydrolase with a pocket-shaped active site
Fecha
2019-12Registro en:
Nature Communications Volume 10, Issue 11 December 2019 Article number 2222
2041-1723
10.1038/s41467-019-09691-z
Autor
Streltsov, Victor A.
Luang, Sukanya
Peisley, Alys
Varghese, Joseph N.
Ketudat Cairns, James R.
Fort, Sebastien
Hijnen, Marcel
Tvaroška, Igor
Arda, Ana
Jiménez-Barbero, Jesús
Alfonso-Prieto, Mercedes
Rovira, Carme
Mendoza, Fernanda
Tiessler-Sala, Laura
Sánchez-Aparicio, José-Emilio
Rodríguez-Guerra, Jaime
M. Lluch, José
Maréchal, Jean-Didier
Masgrau, Laura
Hrmova, Maria
Institución
Resumen
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.