Signal-induced transcriptional activation by Dif requires the dTRAP80 mediator module.
The Mediator complex is the major multiprotein transcriptional coactivator complex in Drosophila melanogaster. Mediator components interact with diverse sets of transcriptional activator proteins to elicit the sophisticated regulation of gene expression. The distinct phenotypes associated with certain mutations in some of the Mediator genes and the specific in vitro interactions of Mediator gene products with transcriptional activator proteins suggest the presence of activator-specific binding subunits within the Mediator complex. However, the physiological relevance of these selective in vitro interactions has not been addressed. Therefore, we analyzed dTRAP80, one of the putative activator-binding subunits of the Mediator, for specificity of binding to a number of natural transcriptional activators from Drosophila. Among the group of activator proteins that requires the Mediator complex for transcriptional activation, only a subset of these proteins interacted with dTRAP80 in vitro and only these dTRAP80-interacting activators were defective for activation under dTRAP80-deficient in vivo conditions. In particular, activation of Drosophila antimicrobial peptide drosomycin gene expression by the NF-kappa B-like transcription factor Dif during induction of the Toll signaling pathway was dependent on the dTRAP80 module. These results, and the indirect support from the dTRAP80 artificial recruitment assay, indicate that dTRAP80 serves as a genuine activator-binding target responsible for a distinct group of activators.
Park
Jin Mo
JM
Department of Biochemistry, National Creative Research Initiative Center for Genome Regulation, Yonsei University. Digital Genomics, Inc., Seoul 120-749, Korea.
Kim
Jung Mo
JM
Kim
Lark Kyun
LK
Kim
Se Nyun
SN
Kim-Ha
Jeongsil
J
Kim
Jung Hoe
JH
Kim
Young-Joon
YJ
D000818:Animals; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism; D056892:Mediator Complex; D011401:Promoter Regions, Genetic; D017434:Protein Structure, Tertiary; D012330:RNA, Double-Stranded / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D051193:Toll-Like Receptors; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors; D014158:Transcription, Genetic; D015533:Transcriptional Activation
D002352:Carrier Proteins; D004268:DNA-Binding Proteins; C084428:Dif protein, Drosophila; D029721:Drosophila Proteins; D018840:HSP70 Heat-Shock Proteins; D018398:Homeodomain Proteins; C471551:MED17 protein, Drosophila; D056892:Mediator Complex; D012330:RNA, Double-Stranded; D011956:Receptors, Cell Surface; D011994:Recombinant Proteins; C068721:Tl protein, Drosophila; D051193:Toll-Like Receptors; D015534:Trans-Activators; D014157:Transcription Factors; C056478:bcd protein, Drosophila