Structural Insights into Rice BGlu1 β-Glucosidase Oligosaccharide Hydrolysis and Transglycosylation

Structural and Enzymatic Characterization of Os3BGlu6, a Rice β-Glucosidase Hydrolyzing Hydrophobic Glycosides and (1→3)- and (1→2)-Linked Disaccharides

“…Among known GH1 structures, Os3BGlu6 was most similar to the plant secreted b-glucosidases white clover cyanogenic b-glucosidase (1CBG; Barrett et al, 1995) and rice Os3BGlu7 b-glucosidase (2RGL; Chuenchor et al, 2008), with the root mean squared deviation (RMSD) of their Ca to those of Os3BGlu6 being 0.81 Å for both structures over 467 and 444 Ca atoms, respectively. For other plant enzymes, the RMSD ranged from 0.83 Å over 445 Ca atoms for white mustard myrosinase (1E4M; Burmeister et al, 2000) to 0.96 Å over 451 atoms for maize ZmGlu1 b-glucosidase (1E1E; Czjzek et al, 2001), which was the same as its RMSD over 423 atoms with human cytosolic b-glucosidase (2E9M; Hayashi et al, 2007).…”

“…Simplified phylogenetic tree of the amino acid sequences of eukaryotic GH1 proteins with known structures and those of rice and Arabidopsis GH1 gene products. The protein sequences of the eukaryotic proteins with known structures are marked with four-character PDB codes for one of their structures, including Trifolium repens cyanogenic b-glucosidase (1CBG; Barrett et al, 1995), Sinapsis alba myrosinase (1MYR; Burmeister et al, 1997), Zea mays ZmGlu1 b-glucosidase (1E1F; Czjzek et al, 2000), Sorghum bicolor Dhr1 dhurrinase (1V02; Verdoucq et al, 2004), Triticum aestivum b-glucosidase (2DGA; Sue et al, 2006), Rauvolfia serpentina strictosidine b-glucosidase (2JF6; Barleben et al, 2007), and Oryza sativa Os3BGlu7 (BGlu1) b-glucosidase (2RGL; Chuenchor et al, 2008) from plants, along with Brevicoryne brassicae myrosinase (1WCG; Husebye et al, 2005), Homo sapiens cytoplasmic (Klotho) b-glucosidase (2E9M; Hayashi et al, 2007), and Phanerochaete chrysosporium (2E3Z; Nijikken et al, 2007), while those encoded in the Arabidopsis and rice genomes are labeled with the systematic names given by Xu et al (2004) and Opassiri et al (2006), respectively. One or two example proteins from each plant are given for each of the eight clusters of genes shared by Arabidopsis (At) and rice (Os) and the Arabidopsis-specific clusters At I (b-glucosidases) and At II (myrosinases), with the number of Arabidopsis or rice enzymes in each cluster given in parentheses.…”

“…The similar structures with great diversity in substrate specificity make plant GH1 enzymes an ideal model system to investigate the structural basis of substrate specificity. To date, seven plant b-glucosidase structures have been reported, including three closely related chloroplastic enzymes from maize (Czjzek et al, 2000(Czjzek et al, , 2001, sorghum (Verdoucq et al, 2004), and wheat (Triticum aestivum; Sue et al, 2006), the cytoplasmic strictosidine b-glucosidase from Rauvolfia serpentine (Barleben et al, 2007), and the secreted enzymes white clover (Trifolium repens) cyanogenic b-glucosidase (Barrett et al, 1995), white mustard (Sinapsis alba) myrosinase (thioglucosidase; Burmeister et al, 1997), and rice Os3BGlu7 (BGlu1; Chuenchor et al, 2008). These enzymes hydrolyze substrates with a range of structures, but they cannot account for the full range of b-glucosidase substrates available in plants, and determining the structural differences that bring about substrate specificity differences in even closely related GH1 enzymes has proven tricky (Verdoucq et al, 2003(Verdoucq et al, , 2004Sue et al, 2006;Chuenchor et al, 2008).…”

Structural Hierarchy of Regulatory Elements in the Folding and Transport of an Intestinal Multidomain Protein

“…LPH domains III and IV share a comparable, quite high degree of sequence identity (around 40%) with highly conserved family 1 glycoside hydrolases of known three-dimensional structure from humans (25), plants (26), fungi (27), and bacteria (28,29). Structure-based sequence alignments with the aforesaid homologous proteins generated by GenTHREADER (30) were used to dissect the LPH domains.…”

Glycoside Hydrolases for Extraction and Modification of Polyphenolic Antioxidants

“…using cellulose, and β-glucan as well as flavonoids as substrates) (Bhatia et al 2002). These differences make enzymes from GH1 interesting models for studies of the relationship between structure and activity (Chuenchor et al 2008).…”