Li Zhijie, Fischer Michael, Satkunarajah Malathy, Zhou Dongxia, Withers Stephen G, Rini James M
Department of Biochemistry, University of Toronto, Toronto, ON, Canada, M5S 1A8.
Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada, M5S 1A8.
Nat Commun. 2017 Aug 4;8(1):185. doi: 10.1038/s41467-017-00255-7.
Protein O-glucosyltransferase 1/Rumi-mediated glucosylation of Notch epidermal growth factor-like (EGF-like) domains plays an important role in Notch signaling. Protein O-glucosyltransferase 1 shows specificity for folded EGF-like domains, it can only glycosylate serine residues in the CXSXPC motif, and it possesses an uncommon dual donor substrate specificity. Using several EGF-like domains and donor substrate analogs, we have determined the structures of human Protein O-glucosyltransferase 1 substrate/product complexes that provide mechanistic insight into the basis for these properties. Notably, we show that Protein O-glucosyltransferase 1's requirement for folded EGF-like domains also leads to its serine specificity and that two distinct local conformational states are likely responsible for its ability to transfer both glucose and xylose. We also show that Protein O-glucosyltransferase 1 possesses the potential to xylosylate a much broader range of EGF-like domain substrates than was previously thought. Finally, we show that Protein O-glucosyltransferase 1 has co-evolved with EGF-like domains of the type found in Notch.POGLUT1 is a protein-O-glucosyltransferase that transfers glucose and xylose to the EGF-like domains of Notch and other signaling receptors. Here the authors report the structure of human POGLUT1 in complexes with 3 different EGF-like domains and donor substrates and shed light on the enzyme's substrate specificity and catalytic mechanism.
蛋白O-葡萄糖基转移酶1/Rumi介导的Notch表皮生长因子样（EGF样）结构域的糖基化在Notch信号传导中起重要作用。蛋白O-葡萄糖基转移酶1对折叠的EGF样结构域具有特异性，它只能对CXSXPC基序中的丝氨酸残基进行糖基化，并且具有罕见的双供体底物特异性。使用几种EGF样结构域和供体底物类似物，我们确定了人蛋白O-葡萄糖基转移酶1底物/产物复合物的结构，这些结构为这些特性的基础提供了机制上的见解。值得注意的是，我们表明蛋白O-葡萄糖基转移酶1对折叠的EGF样结构域的需求也导致了其丝氨酸特异性，并且两种不同的局部构象状态可能是其转移葡萄糖和木糖能力的原因。我们还表明，蛋白O-葡萄糖基转移酶1具有对比以前认为的更广泛的EGF样结构域底物进行木糖基化的潜力。最后，我们表明蛋白O-葡萄糖基转移酶1与Notch中发现的那种类型的EGF样结构域共同进化。POGLUT1是一种蛋白O-葡萄糖基转移酶，可将葡萄糖和木糖转移到Notch和其他信号受体的EGF样结构域。本文作者报道了人POGLUT1与3种不同的EGF样结构域和供体底物形成的复合物的结构，并阐明了该酶的底物特异性和催化机制。
