Lunatic Fringe, Manic Fringe, and Radical Fringe Recognize Similar Specificity Determinants inO-Fucosylated Epidermal Growth Factor-like Repeats

Raajit Rampal, Annie S. Y. Li, Daniel J. Moloney, Stephanie A. Georgiou, Kelvin B. Luther, Aleksandra Nita-Lazar, Robert S. Haltiwanger
2005 Journal of Biological Chemistry  
Notch signaling is a component of a wide variety of developmental processes in many organisms. Notch activity can be modulated by O-fucosylation (mediated by protein O-fucosyltransferase-1) and Fringe, a ␤1,3-N-acetylglucosaminyltransferase that modifies O-fucose in the context of epidermal growth factor-like (EGF) repeats. Fringe was initially described in Drosophila, and three mammalian homologues have been identified, Manic fringe, Lunatic fringe, and Radical fringe. Here for the first time
more » ... for the first time we have demonstrated that, similar to Manic and Lunatic, Radical fringe is also a fucose-specific ␤1,3-N-acetylglucosaminyltransferase. The fact that three Fringe homologues exist in mammals raises the question of whether and how these enzymes differ. Although Notch contains numerous EGF repeats that are predicted to be modified by O-fucose, previous studies in our laboratory have demonstrated that not all O-fucosylated EGF repeats of Notch are further modified by Fringe, suggesting that the Fringe enzymes can differentiate between them. In this work, we have sought to identify specificity determinants for the recognition of an individual O-fucosylated EGF repeat by the Fringe enzymes. We have also sought to determine differences in the biochemical behavior of the Fringes with regard to their in vitro enzymatic activities. Using both in vivo and in vitro experiments, we have found two amino acids that appear to be important for the recognition of an O-fucosylated EGF repeat by all three mammalian Fringes. These amino acids provide an initial step toward defining sequences that will allow us to predict which O-fucosylated EGF repeats are modified by the Fringes. . 3 The abbreviations used are: EGF, epidermal growth factor-like; Bnz-fuc, benzyl-␣-Ofucose; Mfng, Manic fringe; Lfng, Lunatic fringe; Rfng, Radical fringe; Dfng, Drosophila fringe; O-FucT-1, protein O-fucosyltransferase-1; CHO, Chinese hamster ovary; HPAEC, high pH anion exchange chromatography; Ni-NTA, nickel-nitrilotriacetic acid; MS/MS, mass spectrometry/mass spectrometry; HPLC, high pressure liquid chromatography.
doi:10.1074/jbc.m509552200 pmid:16221665 fatcat:iwlrkvdtmvepbbz2ooguubaoom