AtSCO1: a copper chaperone essential during embryogenesis in Arabidopsis thaliana

CAROLINA V. ATTALLAH, ELINA WELCHEN Y DANIEL H. GONZÁLEZ.

Mar del Plata, Pcia. Buenos Aires

Congreso; XLIII Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2007

The assembly of cytochrome c oxidase (COX) involves a number of auxiliary proteins. Some of these proteins are implicated in metallation of the two copper centers present in COX. Yeast Sco1p is a constituent of the mitochondrial inner membrane involved in the formation of the CuA  center and Dsco1 cells are respiratory-deficient. We have identified Arabidopsis plants with T-DNA insertions in two genes that encode proteins with homology to yeast Sco1p. Homozygote mutant plants with insertions in one of these genes, located in chromosome 4, have no obvious phenotype. In turn, segregation analysis of heterozygote mutant plants in the other gene (named AtSCO1, located in chromosome 3) suggests that its function is required at early stages of plant development. Siliques of these plants contain 25% abnormal seeds with embryos arrested at the torpedo stage. To establish a causal link between genotype and phenotype, we used complementation with the AtSCO1 cDNA. This approach allowed us to obtain plants homozygous for the T-DNA insertion in AtSCO1. Sequences upstream from the translation start site of AtSCO1 were introduced into plants in front of the gus gene. Expression of the reporter gene was localized in meristematic tissues, anthers and embryos at different developmental stages. Our results suggest that AtSCO1 function