Arabidopsis thaliana frataxin homolog (AtFH) deficiency increases oxidative stress and modulates Fe-S protein activity in mitochondria

BUSI, M. V.; VALDEZ, H.; CLEMENTE, M.; MALIANDI, M. V.; EDUARDO ZABALETA; ARAYA, A.; DIEGO FABIAN GOMEZ CASATI

Obernai

Congreso; International Congress on Plant Mitochondrial Biology,; 2005

Frataxin is a highly conserved protein from bacteria to mammals that has been proposed to participate in iron-sulfur cluster assembly, mitochondrial iron homeostasis and defense against oxidative stress. We recently reported the cloning of AtFH, a plant gene with significant homology to other members of the frataxin family. Transcription analysis showed that AtFH is ubiquitously expressed with higher levels in flowers. Complementation of a S. cerevisiae mutant (∆yfh) proved that AtFH is a functional protein, because it restored normal rates of respiration, growth, and sensitivity to H2O2. Infiltration of Arabidopsis leaves with H2O2 showed that AtFH is induced compared with control leaves. In AtFH null mutants mRNA levels of Peroxiredoxin, Calreticulin, AOx and GAPDH were induced and we also observed an increased production of superoxide in leaves by histochemical detection. In the absence of AtFH, activity of Fe-S containing enzymes (aconitase, succinate dehydrogenase) is decreased, whereas the activity of malate dehydrogenase (a non-Fe-S-containing enzyme) is unaffected. Considered together, our results support a direct role of AtFH in oxidative stress and in the modulation of Fe-S protein activity in mitochondria.