title: Analysis of nuclear factor-κB (NF-κB) essential modulator (NEMO) binding to linear and lysine-linked ubiquitin chains and its role in the activation of NF-κB.
abstract: Nuclear factor-κB (NF-κB) essential modulator (NEMO), a component of the inhibitor of κB kinase (IKK) complex, controls NF-κB signaling by binding to ubiquitin chains. Structural studies of NEMO provided a rationale for the specific binding between the UBAN (ubiquitin binding in ABIN and NEMO) domain of NEMO and linear (Met-1-linked) di-ubiquitin chains. Full-length NEMO can also interact with Lys-11-, Lys-48-, and Lys-63-linked ubiquitin chains of varying length in cells. Here, we show that purified full-length NEMO binds preferentially to linear ubiquitin chains in competition with lysine-linked ubiquitin chains of defined length, including long Lys-63-linked deca-ubiquitins. Linear di-ubiquitins were sufficient to activate both the IKK complex in vitro and to trigger maximal NF-κB activation in cells. In TNFα-stimulated cells, NEMO chimeras engineered to bind exclusively to Lys-63-linked ubiquitin chains mediated partial NF-κB activation compared with cells expressing NEMO that binds to linear ubiquitin chains. We propose that NEMO functions as a high affinity receptor for linear ubiquitin chains and a low affinity receptor for long lysine-linked ubiquitin chains. This phenomenon could explain quantitatively distinct NF-κB activation patterns in response to numerous cell stimuli.
authors.affiliation: Buchmann Institute for Molecular Life Sciences and Institute of Biochemistry II, Goethe University School of Medicine, Theodor-Stern-Kai 7, D-60590 Frankfurt, Main, Germany.
authors.forename: Tobias
authors.initials: T
authors.lastname: Kensche
authors.forename: Fuminori
authors.initials: F
authors.lastname: Tokunaga
authors.forename: Fumiyo
authors.initials: F
authors.lastname: Ikeda
authors.forename: Eiji
authors.initials: E
authors.lastname: Goto
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Iwai
authors.forename: Ivan
authors.initials: I
authors.lastname: Dikic
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002478:Cells, Cultured; D004622:Embryo, Mammalian / Q000166:cytology; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D057809:HEK293 Cells; D006367:HeLa Cells; D006801:Humans; D051550:I-kappa B Kinase / Q000235:genetics / Q000378:metabolism*; D008239:Lysine / Q000737:chemistry / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D009154:Mutation; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D011485:Protein Binding; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology; D025801:Ubiquitin / Q000737:chemistry / Q000378:metabolism*; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism
chemical_list: C491731:IKBKG protein, human; D016328:NF-kappa B; D014409:Tumor Necrosis Factor-alpha; D025801:Ubiquitin; D044767:Ubiquitin-Protein Ligases; D051550:I-kappa B Kinase; D008239:Lysine