title: Distinct intracellular motifs of Delta mediate its ubiquitylation and activation by Mindbomb1 and Neuralized.
abstract: DSL proteins are transmembrane ligands of the Notch receptor. They associate with a RING (really interesting new gene) family E3 ubiquitin ligase, either Neuralized (Neur) or Mindbomb 1 (Mib1), as a prerequisite to signaling. Although Neur and Mib1 stimulate internalization of DSL ligands, it is not known how ubiquitylation contributes to signaling. We present a molecular dissection of the intracellular domain (ICD) of Drosophila melanogaster Delta (Dl), a prototype DSL protein. Using a cell-based assay, we detected ubiquitylation of Dl by both Neur and Mib1. The two enzymes use distinct docking sites and displayed different acceptor lysine preferences on the Dl ICD. We generated Dl variants that selectively perturb its interactions with Neur or Mib1 and analyzed their signaling activity in two in vivo contexts. We found an excellent correlation between the ability to undergo ubiquitylation and signaling. Therefore, ubiquitylation of the DSL ICD seems to be a necessary step in the activation of Notch.
authors.affiliation: Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, 70013 Heraklion, Crete, Greece.
authors.forename: Aikaterini
authors.initials: A
authors.lastname: Daskalaki
authors.forename: Nevine A
authors.initials: NA
authors.lastname: Shalaby
authors.forename: Kristina
authors.initials: K
authors.lastname: Kux
authors.forename: Giorgos
authors.initials: G
authors.lastname: Tsoumpekos
authors.forename: George D
authors.initials: GD
authors.lastname: Tsibidis
authors.forename: Marc A T
authors.initials: MA
authors.lastname: Muskavitch
authors.forename: Christos
authors.initials: C
authors.lastname: Delidakis
mesh_terms: D020816:Amino Acid Motifs; D000818:Animals; D020134:Catalytic Domain; D029721:Drosophila Proteins / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000378:metabolism*; D004705:Endocytosis; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism*; D051880:Receptors, Notch / Q000378:metabolism; D015398:Signal Transduction; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism*; D054875:Ubiquitination
chemical_list: D029721:Drosophila Proteins; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D051880:Receptors, Notch; C064045:delta protein; C502570:Mib1 protein, Drosophila; D044767:Ubiquitin-Protein Ligases; C071006:neur protein, Drosophila