Department of Bioscience and Biotechnology, Bio/Molecular Informatics Center, Konkuk University, Seoul 143-701, Korea.
J Microbiol Biotechnol. 2010 Oct;20(10):1393-6. doi: 10.4014/jmb.1003.03005.
The attachment of sugar to flavonoids enhances their solubility. Glycosylation is performed primarily by uridine diphosphate-dependent glycosyltransferases (UGTs). The UGT from Bacillus cereus, BcGT-1 transferred three glucose molecules into kaempferol. The structural analysis of BcGT-1 showed that its substrate binding site is wider than that of flavonoid monoglucosyltransferase of plant. In order to create monoglucosyltransferase from BcGT-1, error-prone polymerase chain reaction (PCR) was performed. We analyzed 150 clones. Among them, two mutants generated only kaempferol O-monoglucoside, albeit with reduced reactivity. Unexpectedly, the two mutants harbored mutations in the amino acids located outside of the active sites. Based on the modeled structure of BcGT-1, it was proposed that the local change in the secondary structure of BcGT-1 caused the alteration of triglucosyltransferase into monoglucosyltransferase.
糖与类黄酮的结合增强了它们的溶解度。糖基化主要由尿苷二磷酸依赖性糖基转移酶（UGTs）完成。蜡状芽孢杆菌的 UGT，BcGT-1 将三个葡萄糖分子转移到山柰酚中。BcGT-1 的结构分析表明，其底物结合位点比植物类黄酮单葡萄糖基转移酶的更宽。为了从 BcGT-1 中产生单葡萄糖基转移酶，进行易错聚合酶链反应（PCR）。我们分析了 150 个克隆。其中，两个突变体仅产生山柰酚 O-单葡萄糖苷，尽管反应性降低。出乎意料的是，这两个突变体在活性位点以外的氨基酸中存在突变。基于 BcGT-1 的模型结构，提出 BcGT-1 的二级结构的局部变化导致三葡萄糖基转移酶转变为单葡萄糖基转移酶。
