CLONING OF SCHISTOSOMA-MANSONI TRANSCRIPTION FACTOR NF-YA SUBUNIT - PHYLOGENIC CONSERVATION OF THE HAP-2 HOMOLOGY DOMAIN

The CCAAT-binding factor NF-Y (CBF/CPI) is a heteromeric transcription factor involved in the regulation of a variety of eukaryotic genes. W e identified NF-Y as the CCAAT activity binding to the promoter region of the gene coding for the 28-kDa glutathione S-transferase of the hu man parasite Schistosoma mansoni (Sm28GST). We isolated the NF-YA cDNA from S. mansoni (SmNF-YA): the complete 268 amino acid sequence harbo rs a region in its C-terminal part that shows homology with the subuni t interaction and DNA-binding domains of the mammalian NF-YA; the N-te rminal region has an amino acid composition reminiscent of the mammali an and echinoderm counterparts, rich in glutamine and hydrophobic resi dues, but shows no sequence similarity at the primary level. In vitro synthesized SMNF-YA is able to associate with mammalian NF-YB/C subuni ts in the absence of DNA and to bind to the Sm28GST CCAAT box. Surpris ingly, a monoclonal antibody directed against the non-conserved Q-rich activation domain of mammalian NF-YA supershifts and immunoprecipitat es SMNF-YA, strongly suggesting structure conservation in the activati on domain between divergent species.