Assembly of oligomeric death domain complexes during Toll receptor signaling.
The Drosophila Toll receptor is activated by the endogenous protein ligand Spätzle in response to microbial stimuli in immunity and spatial cues during embryonic development. Downstream signaling is mediated by the adaptor proteins Tube, the kinase Pelle, and the Drosophila homologue of myeloid differentiation primary response protein (dMyD88). Here we have characterized heterodimeric (dMyD88-Tube) and heterotrimeric (dMyD88-Tube-Pelle) death domain complexes. We show that both the heterodimeric and heterotrimeric complexes form kidney-shaped structures and that Tube is bivalent and has separate high affinity binding sites for dMyD88 and Pelle. Additionally we found no interaction between the isolated death domains of Pelle and dMyD88. These results indicate that the mode of assembly of the heterotrimeric dMyD88-Tube-Pelle complex downstream of the activated Toll receptor is unique. The measured dissociation constants for the interaction between the death domains of dMyD88 and Tube and of Pelle and a preformed dMyD88-Tube complex are used to propose a model of the early postreceptor events in Drosophila Toll receptor signaling.
Moncrieffe
Martin C
MC
Department of Biochemistry, Cambridge University, Cambridge CB2 1GA, United Kingdom. mcm35@cam.ac.uk
Grossmann
J Günter
JG
Gay
Nicholas J
NJ
D048868:Adaptor Proteins, Signal Transducing / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D000818:Animals; D000943:Antigens, Differentiation / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D029721:Drosophila Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D004331:Drosophila melanogaster; D008954:Models, Biological; D046912:Multiprotein Complexes / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding / Q000502:physiology; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D020836:Protein Structure, Quaternary / Q000502:physiology; D011971:Receptors, Immunologic / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology*; D051193:Toll-Like Receptors / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
D048868:Adaptor Proteins, Signal Transducing; D000943:Antigens, Differentiation; D029721:Drosophila Proteins; D046912:Multiprotein Complexes; C499312:Myd88 protein, Drosophila; D011971:Receptors, Immunologic; D011994:Recombinant Proteins; C068721:Tl protein, Drosophila; D051193:Toll-Like Receptors; C084727:tub protein, Drosophila; C079896:pll protein, Drosophila; D017346:Protein Serine-Threonine Kinases