BINDING-SITES FOR MAIZE NUCLEAR PROTEINS IN THE SUBTERMINAL REGIONS OF THE TRANSPOSABLE ELEMENT ACTIVATOR

Genetic data suggest that transposition of the maize element Activator (Ac) is modulated by host factors. Using gel retardation and DNase I protection assays we identified maize proteins which bind to seven sub terminal sires in both ends of Ac. Four DNase I-protected sites contai n a GGTAAA sequence, the other three include either GATAAA or GTTAAA. The specificity of the maize protein binding to Ac was verified by usi ng a synthetic fragment containing four GGTAAA motifs as probe and com petitor in gel retardation assays. All seven binding sites are located within regions required in cis for transposition. A maize protein bin ding site with the same sequence has previously been identified in the terminal inverted repeats of the maize Mutator element. Thus, the pro tein, that recognizes this sequence is a good candidate for a regulato ry host factor for Ac transposition.