Importance of site II motifs in ejc core proteins gene expression in arabidopsis thaliana

MUFARREGE EF; GONZÁLEZ DH; CURI GC

San Miguel de Tucumán

Congreso; XLV Reunión Anual de la Sociedad Argentina de Investigación Bioquímica y Biología Molecular (SAIB); 2009

The exon junction complex is involved in mRNA metabolism and is deposited on mRNA as a consequence of splicing. The Mago-Y14 heterodimer is a core component of this complex. We have observed that the promoters of the genes that encode both proteins are active mainly in meristematic regions in Arabidopsis. By means of a bioinformatic search, we detected the presence of site II motifs (TGGGCC/T) in the proximal regions of both promoters. These elements are involved in expression in meristematic cells in other genes. In order to confirm whether these elements are functional, we performed deletions of the respective promoters down to -500 bp (a fragment that included the site II motifs) and site-directed mutagenesis of the motifs. Transformed plants that express the GUSGUS (beta-glucuronidase) gene under the control of these promoter sequences were analyzed by histochemical and fluorometric assays. We found that the short versions produced the same expression patterns as those observed with larger fragments. In plants that contained promoters with mutations in the site II motifs, the expression disappeared. The importance of these motifs was confirmed through band shift assays using fragments from these promoters as probes and plant nuclear extracts. The results obtained suggest that site II motifs are essential for expression of Arabidopsis Mago and Y14 genes in meristematic tissues