Conservation and divergence of NF-Y transcriptional activation function

• Published in: Nucleic acids research 1998-08, Vol.26 (16), p.3800-3805
• Main Authors: Serra, Esteban, Zemzoumi, Khalid, Lardans, Vinca, Dissous, Colette, di Silvio, Alberto, Mantovani, Roberto
• Format: Article
• Language: English
• Subjects: 3T3 Cells; Amino Acid Sequence; Animals; Base Sequence; CCAAT-Enhancer-Binding Proteins; Cloning, Molecular; Conserved Sequence; COS Cells; DNA, Helminth - genetics; DNA-Binding Proteins - chemistry; DNA-Binding Proteins - genetics; DNA-Binding Proteins - metabolism; HeLa Cells; Helminth Proteins - chemistry; Helminth Proteins - genetics; Helminth Proteins - metabolism; Humans; Mice; Molecular Sequence Data; Oligonucleotide Probes - genetics; Protein Conformation; Recombinant Fusion Proteins - chemistry; Recombinant Fusion Proteins - genetics; Recombinant Fusion Proteins - metabolism; Schistosoma mansoni; Schistosoma mansoni - genetics; Sequence Homology, Amino Acid; Trans-Activators - chemistry; Trans-Activators - genetics; Trans-Activators - metabolism; Transcriptional Activation; Transfection
• ISSN: 0305-1048; 1362-4962
• DOI: 10.1093/nar/26.16.3800

The CCAAT-binding protein NF-Y is involved in the regulation of a variety of eukaryotic genes and is formed in higher eukaryotes by three subunits NF-YA/B/C. We have characterized NF-Y of the trematode parasite Schistosoma mansoni and studied the structure and the function of the SMNF-YA subunit. In this work, we present the cloning and sequence analysis of the B subunit of the parasite factor. SMNF-YB contains the conserved HAP-3 homology domain but the remaining part of the protein was found to be highly divergent from all other species. We demonstrated by transfections of GAL4 fusion constructs, that mouse NF-YB does not contain activation domains while the C-terminal part of SMNF-YB has transcriptional activation potential. On the other hand, the N-terminal parts of SMNF-YA and mouse NF-YA were shown to mediate transactivation; the integrity of a large 160 amino acid glutamine-rich domain of NF-YA was required for this function and an adjacent serine- and threonine-rich domain was necessary for full activity in HepG2, but redundant in other cell types. Transactivation domains identified in SMNF-YB are also rich in serine and threonine residues. Our results indicate that serine/threonine-rich sequences from helminth parasites potentiate transcription and that such structures have diverged during evolution within the same transcription factor.