Caspase-mediated processing of the Drosophila NF-kappaB factor Relish.
The NF-kappaB-like transcription factor Relish plays a central role in the innate immune response of Drosophila. Unlike other NF-kappaB proteins, Relish is activated by endoproteolytic cleavage to generate a DNA-binding Rel homology domain and a stable IkappaB-like fragment. This signal-induced endoproteolysis requires the activity of several gene products, including the IkappaB kinase complex and the caspase Dredd. Here we used mutational analysis and protein microsequencing to demonstrate that a caspase target site, located in the linker region between the Rel and the IkappaB-like domain, is the site of signal-dependent cleavage. We also show physical interaction between Relish and Dredd, suggesting that Dredd indeed is the Relish endoprotease. In addition to the caspase target site, the C-terminal 107 aa of Relish are required for endoproteolysis and signal-dependent phosphorylation by the Drosophila IkappaB kinase beta. Finally, an N-terminal serine-rich region in Relish and the PEST domain were found to negatively regulate Relish activation.
Umeå Centre for Molecular Pathogenesis, Umeå University, S-901 87 Umeå, Sweden. Svenja.Stoven@ucmp.umu.se
Svenja
S
Stoven
Neal
N
Silverman
Anna
A
Junell
Marika
M
Hedengren-Olcott
Deniz
D
Erturk
Ylva
Y
Engstrom
Tom
T
Maniatis
Dan
D
Hultmark
D000818:Animals; D001483:Base Sequence; D020169:Caspases / Q000378:metabolism*; D002478:Cells, Cultured; D015500:Chloramphenicol O-Acetyltransferase / Q000235:genetics; D017931:DNA Primers; D029721:Drosophila Proteins / Q000235:genetics* / Q000378:metabolism; D004331:Drosophila melanogaster / Q000276:immunology*; D017353:Gene Deletion; D005786:Gene Expression Regulation; D017930:Genes, Reporter; D007700:Kinetics; D008969:Molecular Sequence Data; D010766:Phosphorylation; D016133:Polymerase Chain Reaction; D017384:Sequence Deletion; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D001616:beta-Galactosidase / Q000235:genetics
D017931:DNA Primers; D029721:Drosophila Proteins; C101626:Rel protein, Drosophila; D014157:Transcription Factors; D015500:Chloramphenicol O-Acetyltransferase; D001616:beta-Galactosidase; D020169:Caspases