A novel l-isoleucine hydroxylating enzyme, l-isoleucine dioxygenase from Bacillus thuringiensis, produces (2S,3R,4S)-4-hydroxyisoleucine

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• 作者：Tomohiro Kodera ; Sergey V. Smirnov ; Natalya N. Samsonova ; Yury I. Kozlov ; Ryokichi Koyama ; Makoto Hibi ; Jun Ogawa ; Kenzo Yokozeki ; Sakayu Shimizu
• 关键词：l-Isoleucine dioxygenase ; 4-Hydroxyisoleucine ; Bacillus thuringiensis ; Diabetes ; Obesity
• 刊名：Biochemical and Biophysical Research Communications
• 出版年：2009
• 出版时间：18 December 2009
• 年：2009
• 卷：390
• 期：3
• 页码：506-510
• 全文大小：333 K

文摘

The unique function of 4-hydroxyisoleucine (4-HIL) is to stimulate glucose-induced insulin secretion in a glucose-dependent manner. 4-HIL is distributed only in certain kinds of plants and mushrooms, but the biosynthetic mechanism of 4-HIL has not been elucidated. Moreover, 4-HIL-producing microorganisms have not been reported. l-isoleucine (l-Ile) hydroxylating activity producing 4-HIL was detected in a cell lysate of Bacillus thuringiensis strain 2e2 AKU 0251 obtained from the mid-late exponential phase of growth. Properties of the purified hydroxylase demonstrated that it is a α-ketoglutaric acid (α-KG) dependent l-Ile dioxygenase (IDO) and requires α-KG, ferric ion, and ascorbic acid for its maximum activity. IDO showed high stereoselectivity in l-Ile hydroxylation producing only (2S,3R,4S)-4-HIL. The N-terminal 22 amino acids sequence revealed high homology to a hypothetical protein (GenBank ID: RBTH_06809) in B. thuringiensis serovar israelensis ATCC 35646. The histidine motif, which is conserved in α-KG dependent dioxygenases, is found in RBTH_06809.