92. コムギおよびライムギにおけるベンゾキサジノン配糖体代謝酵素の構造と座乗染色体の解析(口頭発表,植物化学調節学会第46回大会)

概要

論文の詳細を見る
Benzoxazinones (Bxs) are a phytoanticipin found in wheat, rye, and maize. Bxs are stored in vacuole of intact plants as β-glucosides, and are hydrolyzed by BxGlc glucosidase to release the toxic aglycones. In the former study, we analyzed the crystal structure of the wheat glucosidase. However, the structure of the enzyme complexed with a ligand has not been obtained. In this study, thus, we aimed to analyze the structure containing a ligand in their substrate binding pockets. Additionally, we intended to determine the chromosomal location of the rye glucosidase (ScGlu) and UDP-Glc:Bx glucosyltransferase (ScGT) genes to complete assignment of the loci of Bx-related genes in wheat and rye. Although the structures of the glucosidases complexed with DIMBOA,the 2-hydroxy group of DIMBOA was considered to be far from the catalytic residue. The inactive mutants complexed with a substrate, DIMBOA-Glc, were also analyzed,resulting in determination of the proper location of the substrate in the enzymes. It was shown that Glu-462 forms a hydrogen bond with the glucose moiety of DIMBOA-Glc and moves deeper into the pockets upon the substrate binding. The mutation of Glu-462 into alanine dramatically decreased the enzyme activity, suggesting the crucial role of the residue. The chromosomal locations of ScGT and ScGlu were determined, and the Bx-related genes were revealed to be dispersed into four chromosomes both in wheat and rye.
2011-10-03