title: A novel soybean (Glycine max) gene encoding a family 3 β-glucosidase has high isoflavone 7-O-glucoside-hydrolyzing activity in transgenic rice.
abstract: A previous study demonstrated that purified Glycine max β-glucosidase (GmBGL) could hydrolyze glucosyl isoflavone to the aglyconic form. This study reports the cloning and functional characterization of a soybean cDNA encoding the β-glucosidase. GmBGL was isolated by use of a purified soybean N-terminal amino acid sequence and conserved sequences of β-glucosidase genes from other plants. Sequence analysis of GmBGL revealed an open reading frame of 1884 bp encoding a polypeptide of 627 amino acids with a calculated molecular mass of 69 kDa. Phylogenetic analysis classified the GmBGL into the glycosyl hydrolase 3 family. In soybean, the GmBGL transcript was predominantly accumulated in roots and leaves. To examine the enzymatic activity and substrate specificity, GmBGL was ectopically expressed in transgenic rice. Purified GmBGL protein from transgenic rice could catalyze the hydrolysis of genistin and daidzin to produce genistein and daidzein, respectively, which confirmed GmBGL as a functional β-glucosidase with isoflavone glucoside-hydrolyzing activity. This paper reveals that GmBGL is a key enzyme in transforming glucosyl isoflavones to aglycones in soybean, which may help in genetic manipulation of aglycone-rich soybean seeds.
authors.affiliation: Department of Agricultural Chemistry, National Taiwan University , Taipei 10617, Taiwan.
authors.forename: Chia-Chen
authors.initials: CC
authors.lastname: Hsu
authors.forename: Tsung-Meng
authors.initials: TM
authors.lastname: Wu
authors.forename: Yi-Ting
authors.initials: YT
authors.lastname: Hsu
authors.forename: Chih-Wen
authors.initials: CW
authors.lastname: Wu
authors.forename: Chwan-Yang
authors.initials: CY
authors.lastname: Hong
authors.forename: Nan-Wei
authors.initials: NW
authors.lastname: Su
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D018744:DNA, Plant / Q000737:chemistry / Q000235:genetics; D015870:Gene Expression; D007529:Isoflavones / Q000378:metabolism*; D008969:Molecular Sequence Data; D012275:Oryza / Q000201:enzymology*; D010802:Phylogeny; D030821:Plants, Genetically Modified / Q000201:enzymology*; D016415:Sequence Alignment; D013025:Glycine max / Q000235:genetics*; D013379:Substrate Specificity; D001617:beta-Glucosidase / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*
chemical_list: D018744:DNA, Plant; D007529:Isoflavones; D001617:beta-Glucosidase
keywords: genistein; isoflavones; soybean; transgenic rice; β-glucosidase