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

Molecular animation of the sequence of events involving the glucose product entrapment, incoming substrate binding and glucose displacement in a plant exo-hydrolase HvExoI, and how this sequence of events underlies substrate-product assisted processive catalysis. The movie shows the entrapped glucose molecule in the -1 subsite of the active site, through twelve residues located on seven loops. After the incoming β-D-glucopyranosyl-(1,3)-D-glucose substrate binds in the +1 and putative +2 subsites, the glucose product adjusts its binding patterns and traverses from the -1 subsite through rotations of Arg158 and Asp285 sidechains and associated backbone atoms, into the autonomous and transient lateral cavity, from where it advances through the aperture into the bulk solvent. The video was prepared in Chimera (Pettersen, E. F. et al. J. Comput. Chem. 25, 1605-1612; 2004), using the HD Movie Maker tool.