Hong Su Young, An Chang Long, Cho Kye Man, Lee Sun Mi, Kim Yong Hee, Kim Min Keun, Cho Soo Jeong, Lim Yong Pyo, Kim Hoon, Yun Han Dae
Division of Applied Life Science, Gyeongsang National University, Chinju, Korea.
Biosci Biotechnol Biochem. 2006 Apr;70(4):798-807. doi: 10.1271/bbb.70.798.
A third bgl operon containing bglE, bglF, bglI, and bglA was isolated from Pectobacterium carotovorum subsp. carotovorum LY34 (Pcc LY34). The sequences of BglE, BglF, and Bgll were similar to those of the phosphotransferase system (PTS) components IIB, IIC, and IIA respectively. BglF contains important residues for the phosphotransferase system. The amino acid sequence of BglA showed high similarity to various 6-phospho-beta-glucosidases and to a member of glycosyl hydrolase family 1. Sequence and structural analysis also revealed that these four genes were organized in a putative operon that differed from two operons previously isolated from Pcc LY34, bglTPB (accession no. AY542524) and ascGFB (accession no. AY622309). The transcription regulator for this operon was not found, and the EII complexes for PTS were encoded separately by three genes (bglE, bglF, and bglI). The BglA enzyme had a molecular weight estimated to be 57,350 Da by SDS-PAGE. The purified beta-glucosidase hydrolyzed salicin, arbutin, rhoNPG, rhoNPbetaG6P, and MUG, exhibited maximal activity at pH 7.0 and 40 degrees C, and displayed enhanced activity in the presence of Mg2+ and Ca2+. Two glutamate residues (Glu178 and Glu378) were found to be essential for enzyme activity.
从胡萝卜软腐果胶杆菌胡萝卜软腐亚种LY34（Pcc LY34）中分离出了第三个包含bglE、bglF、bglI和bglA的bgl操纵子。BglE、BglF和Bgll的序列分别与磷酸转移酶系统（PTS）的组分IIB、IIC和IIA的序列相似。BglF含有磷酸转移酶系统的重要残基。BglA的氨基酸序列与各种6-磷酸-β-葡萄糖苷酶以及糖基水解酶家族1的一个成员具有高度相似性。序列和结构分析还表明，这四个基因组成了一个假定的操纵子，该操纵子与先前从Pcc LY34中分离出的两个操纵子bglTPB（登录号AY542524）和ascGFB（登录号AY622309）不同。未发现该操纵子的转录调节因子，PTS的EII复合物由三个基因（bglE、bglF和bglI）分别编码。通过SDS-PAGE估计BglA酶的分子量为57,350 Da。纯化的β-葡萄糖苷酶可水解水杨苷、熊果苷、rhoNPG（对位硝基苯-β-D-葡萄糖苷）、rhoNPβG6P（对位硝基苯-6-磷酸-β-D-葡萄糖苷）和MUG（4-甲基伞形酮基-β-D-葡萄糖醛酸苷），在pH 7.0和40℃时表现出最大活性，并且在Mg2+和Ca2+存在下活性增强。发现两个谷氨酸残基（Glu178和Glu378）对酶活性至关重要。
