Analysis of the cytochrome c promoters from Arabidopsis.

ELINA WELCHEN; IVANA VIOLA; RAQUEL CHAN; DANIEL GONZALEZ

Iguazú, Misiones. Argentina

Congreso; XL Reunión anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular, SAIB.; 2004

SAIB

<!-- /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0cm; margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman";} @page Section1 {size:612.0pt 792.0pt; margin:70.85pt 3.0cm 70.85pt 3.0cm; mso-header-margin:36.0pt; mso-footer-margin:36.0pt; mso-paper-source:0;} div.Section1 {page:Section1;} --> The plant motochondrial respiratory chain ends up in two different pathways, the cyanide-resistant or alternative pathway and the cytochrome c-dependent one. Two nuclear genes encoding cytochrome c (Cytc) are present in Arabidopsis thaliana. To gain insight ibnto the mechanisms of Cytc gene regulation, we have used regions upstream of the both Cytc genes (Cytc-I and Cytc-II) to drive the expression of the β-glucuronidase (GUS) reporter protein in Arabidopsis plants. Histochemical staining indicated that the Cytc genes are differentially expressed in plant tissues. Cytc-I directs the expession  in meristem and pollen, while Cytc-II is expressed in vascular tissues of cotyledons, roots and hypocotils, as well as in pollen and the central leaf vein. The analysis of progressive upstream deletions of the promoters revealed an essential region for Cytc-I expression located between nucleotides -124 and -31. The importance of binding sites for TCP-doain proteins within this region was assessed by mutagenic analysis. For Cytc-II, expression was abolished when nucleotides -172 to -103 were removed. A comparison of upstream sequences between Cytc genes showed both common and different regulatory motifs. An exhaustive analysis of these elements will be helpful to understand the molecualr mechanisms of expression of these genes