Functional and structural differences between isoflavonoid β-glycosidases from Dalbergia sp.

The β-Glucosidases Responsible for Bioactivation of Hydroxynitrile Glucosides in Lotus japonicus

“…The observed ability of LjBGD2 and LjBGD4 (our data) and almond b-glucosidase (Chuankhayan et al, 2007b) to hydrolyze daidzin is in agreement with the hypothesis that the isoflavonoid glucoside-cleaving b-glucosidases have evolved from the hydroxynitrile glucoside-cleaving b-glucosidases, as suggested by the phylogenetic relationship in Figure 7 and by Chuankhayan et al (2007b). Legumes are characterized by containing cyanogenic glucosides as well as isoflavonoid glucosides.…”

“…LjBGD2, LjBGD4, and LjBGD7 form a cluster with TrCBG, a b-glucosidase from white clover that hydrolyzes linamarin. In agreement with the phylogenetic analysis provided by Chuankhayan et al (2007b), the isoflavonoid glucoside-cleaving b-glucosidases from Glycine max and Dalbergia cochinchinensis were found to cluster between hydroxynitrile glucoside-specific b-glucosidases from legumes and P. serotina. Based on the phylogenetic analysis, isoflavonoid glucosidecleaving b-glucosidases in legumes appear to have evolved from the b-glucosidases involved in the hydrolysis of hydroxynitrile glucosides.…”

“…Glycosylation serves to protect the plant against the toxic effects of its own chemical defense system, to increase solubility, and to facilitate storage. Examples of two-component plant defense systems wherein b-glycosidases act as the bioactivator include the a-hydroxynitrile glycosides (cyanogenic glycosides) that are found in numerous different plant species (Poulton, 1990;Hughes, 1993;Bak et al, 2006;Morant et al, 2007;, benzoxazinoid glycosides in Zea mays, Triticum aestivum, and Secale cereale (Niemeyer, 1988;Sue et al, 2000aSue et al, , 2000b, avenacosides in Avena sativa (saponins; Nisius, 1988;Kim et al, 2000), isoflavonoid glycosides in legumes Chuankhayan et al, 2005Chuankhayan et al, , 2007aChuankhayan et al, , 2007bSuzuki et al, 2006), and glucosinolates found mainly in Brassicales (Halkier and Gershenzon, 2006). All of these different types of glycosides contain an O-linked b-glucosidic bond except for the glucosinolates, which are thioglucosides.…”

Crystal Structures of β-Primeverosidase in Complex with Disaccharide Amidine Inhibitors

“…The fact that the hydrophobic side of ␤-1,6-Xyl faces the aglycone suggests that subsites Ϫ2 and ϩ1 could bind substrate in a concerted manner. The homology modeling of a diglycosdase cloned from Dalbergia nigrescens expected that the 6-O-linked sugar would be faced against the aglycone (37).…”

Comparative Analysis of Benzoxazinoid Biosynthesis in Monocots and Dicots: Independent Recruitment of Stabilization and Activation Functions

“…The enzyme mixture of the purified b-GLUs Lj-BGD2 and Lj-BGD4 that are involved in activation of cyanogenic and noncyanogenic hydroxynitril glucosides in Lotus japonicas (Takos et al, 2010) hydrolyze the isoflavonoid-glucoside daidzin (Morant et al, 2008a), although isoflavonoids are not natural substrates for these enzymes. Based on phylogenetic analysis and the promiscuity of the b-GLUs, it has been hypothesized that isoflavonoid glucosidecleaving enzymes have evolved from cyanogenic glucoside activating b-GLUs (Chuankhayan et al, 2007;Morant et al, 2008a). Parallels exist for benzoxazinoids: Cyanogenic glucosides and benzoxazinoids are found in grasses and in Ranunculaceae (Sharples et al, 1972;Vetter, 2000).…”