Publications

• Structural basis of Notch O-glucosylation and O-xylosylation by mammalian protein-O-glucosyltransferase 1 (POGLUT1).

  Li Z., Fischer M., Satkunarajah M., Zhou D., Withers S.G., Rini J.M.

  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 C<sup>1</su ... >> More

  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 C¹XSXPC² 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. << Less

  Nat. Commun. 8:185-185(2017) [PubMed] [EuropePMC]

  This publication is cited by 1 other entry.

• Two novel protein O-glucosyltransferases that modify sites distinct from POGLUT1 and affect Notch trafficking and signaling.

  Takeuchi H., Schneider M., Williamson D.B., Ito A., Takeuchi M., Handford P.A., Haltiwanger R.S.

  The Notch-signaling pathway is normally activated by Notch-ligand interactions. A recent structural analysis suggested that a novel <i>O</i>-linked hexose modification on serine 435 of the mammalian NOTCH1 core ligand-binding domain lies at the interface with its ligands. This serine occurs betwee ... >> More

  The Notch-signaling pathway is normally activated by Notch-ligand interactions. A recent structural analysis suggested that a novel <i>O</i>-linked hexose modification on serine 435 of the mammalian NOTCH1 core ligand-binding domain lies at the interface with its ligands. This serine occurs between conserved cysteines 3 and 4 of Epidermal Growth Factor-like (EGF) repeat 11 of NOTCH1, a site distinct from those modified by protein <i>O</i>-glucosyltransferase 1 (POGLUT1), suggesting that a different enzyme is responsible. Here, we identify two novel protein <i>O</i>-glucosyltransferases, POGLUT2 and POGLUT3 (formerly KDELC1 and KDELC2, respectively), which transfer <i>O</i>-glucose (<i>O</i>-Glc) from UDP-Glc to serine 435. Mass spectrometric analysis of NOTCH1 produced in HEK293T cells lacking <i>POGLUT2</i>, <i>POGLUT3</i>, or both genes showed that either POGLUT2 or POGLUT3 can add this novel <i>O</i>-Glc modification. EGF11 of NOTCH2 does not have a serine residue in the same location for this <i>O</i>-glucosylation, but EGF10 of NOTCH3 (homologous to EGF11 in NOTCH1 and -2) is also modified at the same position. Comparison of the sites suggests a consensus sequence for modification. In vitro assays with POGLUT2 and POGLUT3 showed that both enzymes modified only properly folded EGF repeats and displayed distinct acceptor specificities toward NOTCH1 EGF11 and NOTCH3 EGF10. Mutation of the <i>O</i>-Glc modification site on EGF11 (serine 435) in combination with sensitizing <i>O</i>-fucose mutations in EGF8 or EGF12 affected cell-surface presentation of NOTCH1 or reduced activation of NOTCH1 by Delta-like1, respectively. This study identifies a previously undescribed mechanism for fine-tuning the Notch-signaling pathway in mammals. << Less

  Proc. Natl. Acad. Sci. U.S.A. 115:E8395-E8402(2018) [PubMed] [EuropePMC]

  This publication is cited by 1 other entry.