title: Crystal structures of Arabidopsis thaliana cell-wall invertase mutants in complex with sucrose.
abstract: In plants, cell-wall invertases fulfil important roles in carbohydrate partitioning, growth, development and crop yield. In this study, we report on different X-ray crystal structures of Arabidopsis thaliana cell-wall invertase 1 (AtcwINV1) mutants with sucrose. These structures reveal a detailed view of sucrose binding in the active site of the wild-type AtcwINV1. Compared to related enzyme-sucrose complexes, important differences in the orientation of the glucose subunit could be observed. The structure of the E203Q AtcwINV1 mutant showed a complete new binding modus, whereas the D23A, E203A and D239A structures most likely represent the productive binding modus. Together with a hydrophobic zone formed by the conserved W20, W47 and W82, the residues N22, D23, R148, E203, D149 and D239 are necessary to create the ideal sucrose-binding pocket. D239 can interact directly with the glucose moiety of sucrose, whereas K242 has an indirect role in substrate stabilization. Most probably, K242 keeps D239 in a favourable position upon substrate binding. Unravelling the exact position of sucrose in plant cell-wall invertases is a necessary step towards the rational design of superior invertases to further increase crop yield and biomass production.
authors.affiliation: Laboratorium voor Moleculaire Plantenfysiologie, Faculteit Wetenschappen, Departement Biologie, K.U. Leuven, Kasteelpark Arenberg 31, bus 2434, B-3001 Heverlee, Belgium.
authors.forename: Willem
authors.initials: W
authors.lastname: Lammens
authors.forename: Katrien
authors.initials: K
authors.lastname: Le Roy
authors.forename: André
authors.initials: A
authors.lastname: Van Laere
authors.forename: Anja
authors.initials: A
authors.lastname: Rabijns
authors.forename: Wim
authors.initials: W
authors.lastname: Van den Ende
mesh_terms: D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics; D029681:Arabidopsis Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D018360:Crystallography, X-Ray; D006026:Glycoside Hydrolases / Q000037:antagonists & inhibitors / Q000145:classification / Q000378:metabolism; D008958:Models, Molecular; D009154:Mutation / Q000235:genetics; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D013379:Substrate Specificity; D013395:Sucrose / Q000737:chemistry* / Q000378:metabolism* / Q000494:pharmacology; D043324:beta-Fructofuranosidase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D013395:Sucrose; D006026:Glycoside Hydrolases; C517207:Inv1 protein, Arabidopsis; D043324:beta-Fructofuranosidase