title: An ACT-like domain participates in the dimerization of several plant basic-helix-loop-helix transcription factors.
abstract: The maize basic-helix-loop-helix (bHLH) factor R belongs to a group of proteins with important functions in the regulation of metabolism and development through the cooperation with R2R3-MYB transcription factors. Here we show that in addition to the bHLH and the R2R3-MYB-interacting domains, R contains a dimerization region located C-terminal to the bHLH motif. This protein-protein interaction domain is important for the regulation of anthocyanin pigment biosynthesis by contributing to the recruitment of the C1 R2R3-MYB factor to the C1 binding sites present in the promoters of flavonoid biosynthetic genes. The R dimerization region bares structural similarity to the ACT domain present in several metabolic enzymes. Protein fold recognition analyses resulted in the identification of similar ACT-like domains in several other plant bHLH proteins. We show that at least one of these related motifs is capable of mediating homodimer formation. These findings underscore the function of R as a docking site for multiple protein-protein interactions and provide evidence for the presence of a novel dimerization domain in multiple plant bHLH proteins.
authors.affiliation: Molecular, Cellular, and Developmental Biology Program, Ohio State University, Columbus, Ohio 43210, USA.
authors.forename: Antje
authors.initials: A
authors.lastname: Feller
authors.forename: J Marcela
authors.initials: JM
authors.lastname: Hernandez
authors.forename: Erich
authors.initials: E
authors.lastname: Grotewold
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000378:metabolism*; D051792:Basic Helix-Loop-Helix Proteins / Q000737:chemistry*; D019281:Dimerization; D005786:Gene Expression Regulation; D008969:Molecular Sequence Data; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid; D014157:Transcription Factors / Q000737:chemistry*; D020798:Two-Hybrid System Techniques; D003313:Zea mays / Q000378:metabolism*
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D014157:Transcription Factors