Functional studies of plant mitochondrial copper chaperones. Roles beyond cytochrome c oxidase biogenesis.

GARCÍA L; GONZALEZ DH; WELCHEN E; ATTALLAH C

Congreso; COPPER 2016, 10th International Copper Meeting; 2016

Plant genomes encode putative homologues of mitochondrial proteins involved in copper delivery for cytochrome c oxidase (COX) biogenesis. Two Arabidopsis HCC genes encode proteins with similarity to SCO proteins, involved in copper insertion into COX. Knockout of HCC1 causes embryo lethality and a loss of COX activity, while mutation of HCC2, which lacks the canonical copper binding motif, does not affect COX activity. RNAseq analysis of hcc2 mutants and of plants that express and antisense RNA directed against HCC1 indicated that these plants show increased and decreased expression, respectively, of a set of stress-responsive genes. Decreased expression of stress-responsive genes is also observed in plants that express artificial miRNAs directed against Arabidopsis COX17 genes, which encode copper chaperones of the mitochondrial intermembrane space. The observed changes in gene expression correlate with changes in the sensitivity of the different plant lines to salt stress. In addition, changes in copper content and/or the expression of genes that respond to copper deficiency are observed in some of the lines under study. We postulate that plant mitochondrial copper chaperones have roles beyond COX biogenesis and participate in the regulation of copper homeostasis and stress responses.