Japan Science and Technology Agency (JST), ERATO, Ito Glycotrilogy Project, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
Biochem Biophys Res Commun. 2012 Oct 5;426(4):504-10. doi: 10.1016/j.bbrc.2012.08.112. Epub 2012 Aug 30.
UDP-glucose:glycoprotein glucosyltransferase plays a key role in glycoprotein quality control in the endoplasmic reticulum, by virtue of its ability to discriminate folding states. Although lines of evidence have clarified the ability of UGGT to recognize a partially unfolded protein, its mechanistic rationale has been obscure. In this study, the substrate recognition mechanism of UGGT was studied using synthetic substrate of UGGT. Although UGGT has high extent of surface hydrophobicity, it clearly lacks property of typical molecular chaperones. Furthermore, it was revealed that the addition of the substrate caused secondary structure change of UGGT in a dose-dependent manner, resulting that the K(d) value of the UGGT-substrate interaction was estimated from theoretical formula based on 1:1 complexation between UGGT and the acceptor substrate. Moreover, the kinetic analysis of glucosyltransferase activity of UGGT elucidated Michaelis constant K(m) correctly.
UDP-葡萄糖：糖蛋白葡萄糖基转移酶通过识别折叠状态，在内质网中糖蛋白的质量控制中起着关键作用。尽管有证据表明 UGGT 能够识别部分展开的蛋白质，但它的机械原理尚不清楚。在这项研究中，使用 UGGT 的合成底物研究了 UGGT 的底物识别机制。尽管 UGGT 具有高度的表面疏水性，但它显然缺乏典型分子伴侣的特性。此外，研究还表明，添加底物会导致 UGGT 的二级结构发生剂量依赖性变化，从而可以根据 UGGT 与受体底物之间 1:1 复合物的理论公式来估算 UGGT-底物相互作用的 K(d)值。此外，对 UGGT 的葡萄糖基转移酶活性的动力学分析正确地阐明了米氏常数 K(m)。
