TY - JOUR
T1 - Biochemical and Molecular Characterization of a Barley Seed ß-Glucosidase
AU - Leah, R.
AU - Kigel, J.
AU - Svendsen, I.
AU - Mundy, John Williams
PY - 1995
Y1 - 1995
N2 - A 60-kDa ß-glucosidase (BGQ60) was purified and characterized from seeds of barley (Hordeum vulgare L.). BGQ60 catalytic activity was restricted to the cleavage of short-chain oligosaccharides composed of(1, 2) -,(1, 2, 3) -, and/or(1, 2, 3, 4) -ß-linked glucose or mannose units. These oligosaccharides are the primary products of endosperm cell wall polysaccharide hydrolysis by other enzymes. In keeping with this, complete hydrolysis of the major polysaccharide of barley starchy endosperm cell wall, (1-3,1-4)-ß-glucan, to free glucose was shown to require the concerted action of endo-(1-3,1-4)-ß-glucanase and BGQ60. The complete amino acid sequence of BGQ60 was determined by protein sequencing combined with the deduced sequence of the corresponding cDNA and genomic clones. The BGQ60 primary structure exhibits extensive homology to members of glycosyl hydrolase family 1 (EC 3.2.1.21). Southern and Northern blot analysis with the cDNA as probe indicated that BGQ60 is encoded by a single gene, and that BGQ60 mRNA only accumulates in the starchy endosperm tissue of late developing seeds. The bgq60 structural gene of approximately 5 kilobases contains an open reading frame encoding 485 amino acids interrupted by 9 introns. The complete nucleotide sequence of the bgq60 structural gene represents the first characterized plant gene encoding a ß-glucosidase. The barley BGQ60 is a novel plant ß-glucosidase with a hitherto undescribed specific enzymatic activity. The possible biological functions of BGQ60 during barley seed development and germination are discussed.
AB - A 60-kDa ß-glucosidase (BGQ60) was purified and characterized from seeds of barley (Hordeum vulgare L.). BGQ60 catalytic activity was restricted to the cleavage of short-chain oligosaccharides composed of(1, 2) -,(1, 2, 3) -, and/or(1, 2, 3, 4) -ß-linked glucose or mannose units. These oligosaccharides are the primary products of endosperm cell wall polysaccharide hydrolysis by other enzymes. In keeping with this, complete hydrolysis of the major polysaccharide of barley starchy endosperm cell wall, (1-3,1-4)-ß-glucan, to free glucose was shown to require the concerted action of endo-(1-3,1-4)-ß-glucanase and BGQ60. The complete amino acid sequence of BGQ60 was determined by protein sequencing combined with the deduced sequence of the corresponding cDNA and genomic clones. The BGQ60 primary structure exhibits extensive homology to members of glycosyl hydrolase family 1 (EC 3.2.1.21). Southern and Northern blot analysis with the cDNA as probe indicated that BGQ60 is encoded by a single gene, and that BGQ60 mRNA only accumulates in the starchy endosperm tissue of late developing seeds. The bgq60 structural gene of approximately 5 kilobases contains an open reading frame encoding 485 amino acids interrupted by 9 introns. The complete nucleotide sequence of the bgq60 structural gene represents the first characterized plant gene encoding a ß-glucosidase. The barley BGQ60 is a novel plant ß-glucosidase with a hitherto undescribed specific enzymatic activity. The possible biological functions of BGQ60 during barley seed development and germination are discussed.
U2 - 10.1074/jbc.270.26.15789
DO - 10.1074/jbc.270.26.15789
M3 - Journal article
SN - 0021-9258
VL - 270
SP - 15789
EP - 15797
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 26
ER -