title: Ternary complex formation between MADS-box transcription factors and the histone fold protein NF-YB.
abstract: MADS-box proteins are transcription factors present in different eukaryotic kingdoms. In contrast to plants, for mammalian and yeast MADS-box proteins ternary complex formation with unrelated transcription factors was reported. We show here the first identification of such ternary interaction in plants. A rice seed-specific NF-YB was identified as partner of OsMADS18 by two-hybrid screening. NF-YB contains a histone fold motif, HFM,(1) and is part of the trimeric CCAAT-binding NF-Y complex. OsMADS18, alone or in combination with a natural partner, interacts with OsNF-YB1 through the MADS and I regions. The mouse NF-YB also associates with OsMADS18 in vivo and in vitro as a NF-YB-NF-YC dimer. Other rice MADS-box proteins do not interact in these assays, indicating specificity for the interaction. OsNF-YB1 is capable of heterodimerizing with NF-YC, but not trimerizing with NF-YA, thus precluding CCAAT binding. Mutation of the variant Asp at position 99 of the HFM alpha2-helix into a conserved serine recovers the capacity to interact with NF-YA, but not with DNA. This is the first indication that members of the NF-YB family work through mechanisms independent of the CCAAT box.
authors.affiliation: Dipartimento di Genetica e Biologia dei Microrganismi, Universitá di Milano, Via Celoria 26, 20133 Milano, Italy.
authors.forename: Simona
authors.initials: S
authors.lastname: Masiero
authors.forename: Carol
authors.initials: C
authors.lastname: Imbriano
authors.forename: Federica
authors.initials: F
authors.lastname: Ravasio
authors.forename: Rebecca
authors.initials: R
authors.lastname: Favaro
authors.forename: Nilla
authors.initials: N
authors.lastname: Pelucchi
authors.forename: Mirella Sari
authors.initials: MS
authors.lastname: Gorla
authors.forename: Roberto
authors.initials: R
authors.lastname: Mantovani
authors.forename: Lucia
authors.initials: L
authors.lastname: Colombo
authors.forename: Martin M
authors.initials: MM
authors.lastname: Kater
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D017360:Arabidopsis; D023081:CCAAT-Binding Factor / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism*; D026161:MADS Domain Proteins / Q000378:metabolism*; D051379:Mice; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000378:metabolism*; D011485:Protein Binding; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D011817:Rabbits; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016415:Sequence Alignment; D014157:Transcription Factors; D020798:Two-Hybrid System Techniques
chemical_list: D023081:CCAAT-Binding Factor; D004268:DNA-Binding Proteins; D026161:MADS Domain Proteins; C492060:Nfya protein, mouse; C492062:Nfyb protein, mouse; D010940:Plant Proteins; D014157:Transcription Factors