Conservation and divergence of NF-Y transcriptional activation function.
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-richsequences from helminth parasites potentiate trans-cription and that such structures have diverged during evolution within the same transcription factor.
Unité INSERM 167, Institut Pasteur Lille, 1, rue du Professeur Calmette, 59019 Lille, France.
E
E
Serra
K
K
Zemzoumi
A
A
di Silvio
R
R
Mantovani
V
V
Lardans
C
C
Dissous
D016475:3T3 Cells; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D022762:CCAAT-Enhancer-Binding Proteins; D019556:COS Cells; D003001:Cloning, Molecular; D017124:Conserved Sequence; D018509:DNA, Helminth / Q000235:genetics; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D006367:HeLa Cells; D015801:Helminth Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D015345:Oligonucleotide Probes / Q000235:genetics; D011487:Protein Conformation; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012550:Schistosoma mansoni / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D015534:Trans-Activators / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D015533:Transcriptional Activation; D014162:Transfection
D022762:CCAAT-Enhancer-Binding Proteins; D018509:DNA, Helminth; D004268:DNA-Binding Proteins; D015801:Helminth Proteins; D015345:Oligonucleotide Probes; D011993:Recombinant Fusion Proteins; D015534:Trans-Activators