An Chang Long, Lim Woo Jin, Hong Su Young, Kim Eun Ju, Shin Eun Chule, Kim Min Keun, Lee Jong Reoul, Park Sang Ryeol, Woo Jong Gyu, Lim Yong Pyo, Yun Han Dae
Division of Applied Life Science, Gyeongsang National University, Chinju, Korea.
Biosci Biotechnol Biochem. 2004 Nov;68(11):2270-8. doi: 10.1271/bbb.68.2270.
A putative bgl operon of Pectobacterium carotovorum subsp. carotovorum LY34 (Pcc LY34) was isolated. Sequence analysis of the 5,557 bp cloned DNA fragment (accession no. AY542524) showed three open reading frames (bglT, bglP, and bglB) predicted to encode 287, 633, and 468 amino acid proteins respectively. BglT and BglP ORFs show high similarity to that of the Pectobacterium chrysanthemi ArbG antiterminator and ArbF permease respectively. Also, the latter contains most residues important for phosphotransferase activity. The amino acid sequence of BglB showed high similarity to various beta-glucosidases and is a member of glycosyl hydrolase family 1. The purified BglB enzyme hydrolyzed salicin, arbutin, pNPG, and MUG. The molecular weight of the enzyme was estimated to be 53,000 Da by SDS-PAGE. The purified beta-glucosidase exhibited maximal activity at pH 7.0 and 40 degrees C, and its activity was enhanced in the presence of Mg(2+). Two glutamate residues (Glu(173) and Glu(362)) were found to be essential for enzyme activity.
胡萝卜软腐果胶杆菌胡萝卜软腐亚种LY34（Pcc LY34）的一个假定bgl操纵子被分离出来。对5557 bp克隆DNA片段（登录号AY542524）的序列分析显示有三个开放阅读框（bglT、bglP和bglB），预计分别编码287、633和468个氨基酸的蛋白质。BglT和BglP开放阅读框分别与菊苣果胶杆菌的ArbG抗终止子和ArbF通透酶具有高度相似性。此外，后者含有对磷酸转移酶活性最重要的大多数残基。BglB的氨基酸序列与各种β-葡萄糖苷酶具有高度相似性，是糖基水解酶家族1的成员。纯化的BglB酶可水解水杨苷、熊果苷、对硝基苯-β-D-葡萄糖苷（pNPG）和4-甲基伞形酮基-β-D-葡萄糖苷（MUG）。通过SDS-PAGE估计该酶的分子量为53,000 Da。纯化的β-葡萄糖苷酶在pH 7.0和40℃时表现出最大活性，并且在Mg(2+)存在下其活性增强。发现两个谷氨酸残基（Glu(173)和Glu(362)）对酶活性至关重要。
