1v03
|
CRYSTAL STRUCTURE OF THE SORGHUM BICOLOR DHURRINASE 1
OverviewOverview
Plant beta-glucosidases play a crucial role in defense against pests. They, cleave, with variable specificity, beta-glucosides to release toxic, aglycone moieties. The Sorghum bicolor beta-glucosidase isoenzyme Dhr1 has, a strict specificity for its natural substrate dhurrin, (p-hydroxy-(S)-mandelonitrile-beta-D-glucoside), whereas its close, homolog, the maize beta-glucosidase isoenzyme Glu1, which shares 72%, sequence identity, hydrolyzes a broad spectrum of substrates in addition, to its natural substrate, 2-O-beta-D-glucopyranosyl-4-hydroxy-7-methoxy-1,4-benzoxaxin-3-one., Structural data from enzyme.substrate complexes of Dhr1 show that the mode, of aglycone binding differs from that previously observed in the, homologous maize enzyme. Specifically, the data suggest that Asn(259), Phe(261), and Ser(462), located in the aglycone-binding site of S. bicolor, Dhr1, are crucial for aglycone recognition and binding. The tight binding, of the aglycone moiety of dhurrin promotes the stabilization of the, reaction intermediate in which the glycone moiety is in a deformed (1)S(3), conformation within the glycone-binding site, ready for nucleophilic, attack to occur. Compared with the broad specificity maize, beta-glucosidase, this different binding mode explains the narrow, specificity of sorghum dhurrinase-1.
About this StructureAbout this Structure
1V03 is a Single protein structure of sequence from Sorghum bicolor with BGC, IPH and CCN as ligands. Active as Beta-glucosidase, with EC number 3.2.1.21 Known structural/functional Site: . Full crystallographic information is available from OCA.
ReferenceReference
Structural determinants of substrate specificity in family 1 beta-glucosidases: novel insights from the crystal structure of sorghum dhurrinase-1, a plant beta-glucosidase with strict specificity, in complex with its natural substrate., Verdoucq L, Moriniere J, Bevan DR, Esen A, Vasella A, Henrissat B, Czjze M, J Biol Chem. 2004 Jul 23;279(30):31796-803. Epub 2004 May 17. PMID:15148317
Page seeded by OCA on Tue Dec 18 18:20:07 2007