Mapping sequences required for nuclear localization and the transcriptional activation function of the Arabidopsis protein AINTEGUMENTA

The Arabidopsis thaliana floral development protein AINTEGUMENTA (ANT) is a member of a large family of DNA binding proteins (AP2/ERF family) that control plant growth and development in response to developmental or environmental signals. Transcriptional activation and/or repression activities have been demonstrated for several members of this protein family. We have used fusions between ANT and the GAL4 DNA binding domain to identify an 80 amino acid sequence important for the transcriptional activation function of ANT. This region shows similarity to transcriptional activation domains in other proteins, as it is rich in Ser/Thr, Gln/Asn, and acidic amino acids. We also demonstrate that ANT can activate gene expression in Arabidopsis plants through binding to a DNA sequence corresponding to an in vitro determined ANT binding site. Finally, we show that ANT is nuclear localized and that the sequence KKKR (amino acids 252-255) is required for nuclear localization of the protein.