Caspase-mediated processing of the Drosophila NF-kappaB factor Relish
Department of Medicine, Division of Infectious Diseases and Immunology
Animals; Base Sequence; Caspases; Cells, Cultured; Chloramphenicol O-Acetyltransferase; DNA Primers; Drosophila Proteins; Drosophila melanogaster; Gene Deletion; Gene Expression Regulation; Genes, Reporter; Kinetics; Molecular Sequence Data; Phosphorylation; Polymerase Chain Reaction; Sequence Deletion; Transcription Factors; beta-Galactosidase
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.
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Citation: Proc Natl Acad Sci U S A. 2003 May 13;100(10):5991-6. Epub 2003 May 5. Link to article on publisher's site