Analysis of the CYTC-2 promoter from Arabidopsis thaliana

PRENDES L; WELCHEN E.; GONZÁLEZ D.

Pinamar, Argentina

Congreso; SAIB (Sociedad Argentina de Investigación en Bioquímica y Biología Molecular); 2005

SAIB, PABMB, SAN

  Mitochondrial biogenesis involves the expression of genes located in the nucleus and within the organelle. To analyze the molecular mechanisms involved in the expression of plant respiratory chain components involved in cytochrome c-dependent respiration, we have characterized the promoter region of the Arabidopsis cytc-2 (At4g10040) gene, one of the two genes encoding cytochrome c. Plants transformed with cytc-2 promoter/gus fusions showed expression in vascular tissues of cotyledons, leaves, roots and hypocotyls, and also in anthers. Quantitative measurements in extracts prepared from different organs suggested that expression of cytc-2 is higher in leaves than in flowers and roots. The analysis of progressive upstream deletions showed that a deletion down to nucleotide -256, that excludes two copies of the site II element (TGGGCC/T), produces a general decrease in GUS expression levels, while a further deletion down to nucleotide -140 completely abolished expression. The site II element was found to be essential for cytc-1 (At1g22840) gene expression, together with a telo box motif (AAACCCTA). A site-directed mutation in a G-box (CACGTG) element present at -172 of the cytc-2 promoter produced a strong decrease in expression. These observations suggest that site II and G-box elements, among others, are implicated in cytc-2 gene expression. Accordingly, cytc promoters would be composed of common and gene-specific regulatory elements that produce differential expression patterns.