Multiple O-glucosylation sites on Notch function as a buffer against temperature-dependent loss of signaling

Development. 2011 Aug;138(16):3569-78. doi: 10.1242/dev.068361. Epub 2011 Jul 19.


Mutations in Drosophila rumi result in a temperature-sensitive loss of Notch signaling. Rumi is a protein O-glucosyltransferase that adds glucose to EGF repeats with a C-X-S-X-P-C consensus sequence. Eighteen of the 36 EGF repeats in the Drosophila Notch receptor contain the consensus O-glucosylation motif. However, the contribution of individual O-glucose residues on Notch to the regulation of Notch signaling is not known. To address this issue, we carried out a mutational analysis of these glucosylation sites and determined their effects on Notch activity in vivo. Our results indicate that even though no single O-glucose mutation causes a significant decrease in Notch activity, all of the glucose residues on Notch contribute in additive and/or redundant fashions to maintain robust signaling, especially at higher temperatures. O-glucose motifs in and around the ligand-binding EGF repeats play a more important role than those in other EGF repeats of Notch. However, a single O-glucose mutation in EGF12 can be compensated by other O-glucose residues in neighboring EGF repeats. Moreover, timecourse cell aggregation experiments using a rumi null cell line indicate that a complete lack of Rumi does not affect Notch-Delta binding at high temperature. In addition, rumi fully suppresses the gain-of-function phenotype of a ligand-independent mutant form of Notch. Our data suggest that, at physiological levels of Notch, the combined effects of multiple O-glucose residues on this receptor allow productive S2 cleavage at high temperatures and thereby serve as a buffer against temperature-dependent loss of Notch signaling.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Drosophila Proteins / genetics
  • Drosophila Proteins / metabolism*
  • Drosophila melanogaster / genetics
  • Drosophila melanogaster / growth & development*
  • Drosophila melanogaster / metabolism*
  • Gene Expression Regulation, Developmental
  • Genome, Insect
  • Glucose / metabolism
  • Glucosyltransferases / genetics
  • Glucosyltransferases / metabolism*
  • Mutation
  • Receptors, Notch / genetics
  • Receptors, Notch / metabolism*
  • Signal Transduction*
  • Temperature
  • Transgenes


  • Drosophila Proteins
  • N protein, Drosophila
  • Receptors, Notch
  • Glucosyltransferases
  • Rumi protein, Drosophila
  • Glucose