Prodos is a conserved transcriptional regulator that interacts with dTAF(II)16 in Drosophila melanogaster

The transcription factor TFIID is a multiprotein complex that includes the TATA box binding protein (TBP) and a number of associated factors, TAF(II). Prodos (PDS) is a conserved protein that exhibits a histone fold domain (H FD). In yeast two-hybrid tests using PDS as bait, we cloned the Drosophila TAF(II), dTAF(II)16, as a specific PDS target. dTAF(II)16 is closely relate d to human TAF(II)30 and to another recently discovered Drosophila TAF, dTA F(II)24. PDS and dTAF(II)24 do not interact, however, thus establishing a f unctional difference between these dTAFs. The PDS-dTAF(II)16 interaction is mediated by the HFD motif in PDS and the N terminus in dTAF(II)16, as indi cated by yeast two-hybrid assays with protein fragments. Luciferase-reporte d transcription tests in transfected cells show that PDS or an HFD-containi ng fragment activates transcription only with the help of dTAF(II)16 and TB P. Consistent with this, the eye phenotype of flies expressing a sev-Ras1 c onstruct is modulated by PDS and dTAF(II)16 in a gene dosage-dependent mann er. Finally, we show that PDS function is required for cell viability in so matic mosaics. These findings indicate that PDS is a novel transcriptional coactivator that associates with a member of the general transcription fact or TFIID.