Interaction of the plant homeodomain protein WUSCHEL with DNA

ARIEL, FD; ARCE, A; CHAN, RL

Pinamar

Congreso; 10th Panamerican Association for Biochemistry and Molecular Biology; 2005

Panamerican Association for Biochemistry and Molecular Biology

WUSCHEL is an Arabidopsis gene that encodes an homeodomain (HD) protein, whose family has been named after itself. Its HD, a conserved compact domain that directly contacts DNA, presents extra amino acid residues in two sites of the molecule, which could result in an atypical structure and have unpredictable effects on the interaction with DNA. Wushcel has been characterized as a key regulator of meristem development, and apparently plays a critic role in the maintenance of embryonic cell identity. In this study, the HD of Wuschel was expressed as a fusion with GST from Schistosoma japonicum and purified by affinity chromatography. The binding sequence, CTCAG, was determined by selecting binding sites from random ?sequence oligonucleotides through several rounds of binding and amplification (SELEX). In vitro DNA binding, followed by electrophoretic movility shift assays indicated that this HD has a higher affinity to the SELEX resulting sequence than to the TAAT core, proposed to be the target sequence of Wuschel in the second intron of the floral homeotic gene AGAMOUS, by analogy with typical HD binding sequences. Nevertheless, the sequence bound with highest affinity in vitro is also present in the same region, , what suggests that an alternative mechanism is having place in the transcriptional regulation of the gene AGAMOUS.