Regulated assembly of the Toll signaling complex drives Drosophila dorsoventral patterning.
In Drosophila, the Toll pathway establishes the embryonic dorsoventral axis and triggers innate immune responses to infection. The transmembrane receptor Toll acts through three death domain-containing proteins, the kinase Pelle and the adapters Tube and MyD88, in signaling to downstream NF-kappaB-like transcription factors. Here, we delineate the critical events in the earliest stages of Toll signaling. Mutational studies based on structural modeling reveal that the direct interaction of the bivalent Tube death domain with MyD88 is critical for signaling in vivo. The complex of MyD88 and Tube forms prior to signaling and is localized to the embryonic plasma membrane by MyD88. Upon Toll homodimerization, this complex is rapidly recruited to Toll. Binding of Pelle to the MyD88-Tube complex promotes Pelle activation, leading to degradation of the IkappaB-like inhibitor, Cactus. Together, these experiments convert a linear picture of gene function into a dynamic mechanistic and structural understanding of signaling complex assembly and function.
Sun
Huaiyu
H
Section of Cell and Developmental Biology, Division of Biological Sciences, Center for Molecular Genetics, University of California at San Diego, La Jolla, CA, USA.
Towb
Par
P
Chiem
Daniel N
DN
Foster
Byron A
BA
Wasserman
Steven A
SA
D000483:Alleles; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D019521:Body Patterning; D002478:Cells, Cultured; D019281:Dimerization; D004330:Drosophila / Q000166:cytology / Q000196:embryology*; D029721:Drosophila Proteins / Q000737:chemistry / Q000378:metabolism*; D004815:Epidermal Growth Factor / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D017930:Genes, Reporter; D008156:Luciferases / Q000378:metabolism; D008239:Lysine / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011233:Precipitin Tests; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D011956:Receptors, Cell Surface / Q000737:chemistry / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D015398:Signal Transduction; D051193:Toll-Like Receptors
D029721:Drosophila Proteins; D011956:Receptors, Cell Surface; D011994:Recombinant Proteins; C068721:Tl protein, Drosophila; D051193:Toll-Like Receptors; D004815:Epidermal Growth Factor; D008156:Luciferases; D008239:Lysine