Threonine 66 in the death domain of IRAK-1 is critical for interaction with signaling molecules but is not a target site for autophosphorylation.
Ligand binding in the TLR/IL-1R family results in the transient formation of an intracellular signaling complex, which contains, amongst others, the serine/threonine-specific kinase IL-1R-associated kinase 1 (IRAK-1). Concomitantly, the kinase function of IRAK-1 becomes activated, resulting in massive autophosphorylation and finally in the dissociation of the initially constituted signaling complex. The death domain (DD) of IRAK-1 mediates the interaction with other molecules of the signaling complex, e.g., the adaptor MyD88, the silencer Tollip, and the activator kinase IRAK-4. The conserved threonine at position 66 (T66), located within the DD, is a putative autophosphorylation target site. Here, we provide evidence that T66 critically impacts the secondary structure of the IRAK-1 DD. Thereby, it ensures the transient manner of interactions between IRAK-1 and the other signaling molecules. This essential role, however, is not regulated by phosphorylation of T66 itself.
Deptartment of Pharmacology, Hannover Medical School, Hannover, Germany. neumann.detlef@mh-hannover.de
Detlef
D
Neumann
Christian
C
Kollewe
Andreas
A
Pich
Ping
P
Cao
Klaus
K
Resch
Michael U
MU
Martin
D002478:Cells, Cultured; D031541:Fluorescence Resonance Energy Transfer; D005822:Genetic Vectors; D006801:Humans; D015151:Immunoblotting; D047468:Immunoprecipitation; D053592:Interleukin-1 Receptor-Associated Kinases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D007376:Interleukin-2 / Q000378:metabolism; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism*; D007668:Kidney / Q000378:metabolism; D008970:Molecular Weight; D053594:Myeloid Differentiation Factor 88 / Q000235:genetics / Q000378:metabolism*; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation; D015398:Signal Transduction; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013912:Threonine / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
D007376:Interleukin-2; D047908:Intracellular Signaling Peptides and Proteins; C507779:MYD88 protein, human; D053594:Myeloid Differentiation Factor 88; D016328:NF-kappa B; C410602:TOLLIP protein, human; D013912:Threonine; C507768:IRAK1 protein, human; C507773:IRAK4 protein, human; D053592:Interleukin-1 Receptor-Associated Kinases