title: Identification of functional domains in the maize transcriptional activator C1: comparison of wild-type and dominant inhibitor proteins.
abstract: Genes encoding fusions between the maize regulatory protein C1 and the yeast transcriptional activator GAL4 and mutant C1 proteins were assayed for their ability to trans-activate anthocyanin biosynthetic genes in intact maize tissues. The putative DNA-binding region of C1 fused to the transcriptional activation domain of GAL4 activated transcription of anthocyanin structural gene promoters in c1 aleurones, c1 Rscm2 embryos, and c1 r embryogenic callus. Cells receiving these constructs accumulated purple anthocyanin pigments. The C1 acidic region fused to the GAL4 DNA-binding domain activated transcription of a GAL4-regulated promoter. An internal deletion of C1 also induced pigmentation; however, frameshifts in either the amino-terminal basic or carboxy-terminal acidic region blocked trans-activation, and the latter generated a dominant inhibitory protein. Fusion constructs between the wild-type C1 cDNA and the dominant inhibitor allele C1-I cDNA were used to identify the amino acid changes in C1 responsible for the C1-I inhibitory phenotype. Results from these studies establish that amino acids within the myb-homologous domain are critical for transcriptional activation.
authors.affiliation: U.S. Department of Agriculture/University of California, Berkeley, Albany 94710.
authors.forename: S A
authors.initials: SA
authors.lastname: Goff
authors.forename: K C
authors.initials: KC
authors.lastname: Cone
authors.forename: M E
authors.initials: ME
authors.lastname: Fromm
mesh_terms: D000872:Anthocyanins / Q000235:genetics*; D002872:Chromosome Deletion; D003001:Cloning, Molecular; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D016368:Frameshift Mutation; D017343:Genes, Plant; D005816:Genetic Complementation Test; D010940:Plant Proteins; D010957:Plasmids; D011401:Promoter Regions, Genetic; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D015533:Transcriptional Activation; D003313:Zea mays / Q000235:genetics*
chemical_list: D000872:Anthocyanins; C067401:C1 protein, Zea mays; D004268:DNA-Binding Proteins; D010940:Plant Proteins; D014157:Transcription Factors