title: Interaction of maize Opaque-2 and the transcriptional co-activators GCN5 and ADA2, in the modulation of transcriptional activity.
abstract: Maize Opaque-2 (ZmO2), a bZip class transcription factor has been shown to activate the transcription of a series of genes expressed in the maturation phase of endosperm development. Activation requires the presence of one or more enhancer binding sites, which confer the propensity for activation by ZmO2 on heterologous promoters and in heterologous plant cell types, such as tobacco mesophyll protoplasts. The region of ZmO2 required for conferring transcriptional activation has been localised to a stretch of acidic residues in the N-terminal portion of the ZmO2 sequence, which is conserved between O2-related bZip factor sequences. Previously we identified the maize homologues of yeast transcriptional co-activators GCN5 and ADA2 that are implicated in nucleosome modification and transcription. In the present study we have shown that transcriptional modulation by ZmO2 involves the intranuclear interaction of ZmO2 with ZmADA2 and ZmGCN5. Förster resonance energy transfer (FRET) based techniques have enabled us to estimate the intracellular site of these intermolecular interactions. As a functional readout of these intranuclear interactions, we used the ZmO2 responsive maize b-32 promoter to drive the beta-glucuronidase (GUS) in the presence and absence of ZmGCN5 and ZmADA2. Our results suggest that the likely recruitment of ZmADA2 and ZmGCN5 modulates the transactivation of b-32 promoter by ZmO2 and that there may be a competition between ZmGCN5 and ZmO2 for binding to the amino-terminal of ZmADA2. The results may be taken as a paradigm for other processes of transcriptional modulation in planta involving acidic activation domains.
authors.affiliation: Max Planck Institute for Plant Breeding Research, Carl-von-Linné Weg 10, Cologne, Germany.
authors.forename: Riyaz A
authors.initials: RA
authors.lastname: Bhat
authors.forename: Jan W
authors.initials: JW
authors.lastname: Borst
authors.forename: Marcus
authors.initials: M
authors.lastname: Riehl
authors.forename: Richard D
authors.initials: RD
authors.lastname: Thompson
mesh_terms: D000123:Acetyltransferases / Q000235:genetics / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D001665:Binding Sites / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D031541:Fluorescence Resonance Energy Transfer / Q000379:methods; D005966:Glucuronidase / Q000235:genetics / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D051548:Histone Acetyltransferases; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D018613:Microscopy, Confocal; D008969:Molecular Sequence Data; D059828:Plant Cells; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D010944:Plants / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding; D011523:Protoplasts / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic / Q000235:genetics; D015533:Transcriptional Activation / Q000235:genetics; D014162:Transfection
chemical_list: D001426:Bacterial Proteins; C485182:Cyan Fluorescent Protein; D004268:DNA-Binding Proteins; D008164:Luminescent Proteins; D010940:Plant Proteins; D011993:Recombinant Fusion Proteins; D015534:Trans-Activators; D014157:Transcription Factors; C067402:opaque-2 protein, Zea mays; C054562:yellow fluorescent protein, Bacteria; D049452:Green Fluorescent Proteins; D000123:Acetyltransferases; D051548:Histone Acetyltransferases; D005966:Glucuronidase