FUNCTIONAL CHARACTERIZATION OF GENES FROM THE Arabidopsis thaliana OXR (OXIDATION RESISTANCE) FAMILY

COLOMBATTI, FRANCISCO; GONZALEZ, DANIEL H.; WELCHEN, ELINA

San Miguel de Tucumán.

Congreso; XLV Reunión Anual Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2009

Plants respond to oxidative stress setting up several defense lines. The first one involves scavengers that remove toxic molecules from the cell. When this barrier is overcome, proteins that prevent or repair the effect of oxidative damage in cell structures come into play. Human OXR1 (oxidation resistance 1) is a mitochondrial protein member of a conserved family of eukaryotic proteins involved in the prevention of oxidative DNA damage. We characterized two Arabidopsis thaliana genes, AtOXR1 (At2g05590) and AtOXR2 (At4g39870), that encode proteins with similarity to human and yeast OXR1. We found that AtOXR1 suppresses the oxidative mutator phenotype when expressed in an E. coli strain that lacks enzymes for the DNA repair system. Plants that overexpress these proteins show increased root length in MS medium and after paraquat treatment. Additionally, these plants have reduced levels of reactive oxygen species (ROS) and of transcripts from the ROS inducible AOX1a gene, encoding the mitochondrial alternative oxidase, under normal growth conditions and under abiotic stress generated by salicylic acid, 3- aminotriazole and UV-B treatments. We conclude that the Arabidopsis OXR proteins play a role in defense mechanisms against oxidative stress, preventing or repairing the damage generated by ROS toxicity.