Two mitochondrial Sco proteins differentially affect salt stress responses in A. thaliana

GONZALEZ DH; WELCHEN E; MANSILLA N

Congreso; LII Reunión Anual de la Sociedad Argentina de Investigaciones en Bioquímica y Biología Molecular (SAIB); 2016

Cytochrome c oxidase (CcO) is the last complex of the mitochondrial electron transport chain. Arabidopsis HCC1 is a homolog of Sco proteins involved in the delivery and insertion of copper into CcO. Another Sco protein, HCC2, is only present in plants and does not have a copper binding domain. To further study the role of HCC1 and HCC2, we analyzed global expression profiles of knockout mutants in HCC2 (hcc2) and antisense plants for HCC1 (asHCC1). Both plant genotypes present opposite transcriptional profiles in numerous Gene Ontology terms. For instance, hcc2 plants exhibit higher levels of transcripts related to stress responses, while asHCC1 plants show decreased levels. In agreement with this, they show differential responses to salt stress: hcc2 plants are more tolerant than wild-type and asHCC1 plants are more sensitive. Likewise, transcripts of stress-responsive genes show earlier or increased induction in asHCC1 plants after long term treatments but the short term response, which is known to be essential for plant survival, is diminished or abolished. An opposite behavior is observed in hcc2 plants. This points to a role of mitochondria in the modulation of the response of plants to stress. Particularly, Sco proteins seem to have developed roles beyond CcO assembly during plant evolution.