Cloning and characterization of maize frataxin homologs

BUCHENSKY C.; CARRILLO, M; BUSI, M.V.; GOMEZ-CASATI, D.F

Rosario

Congreso; 8th International Conference for Plant Mitochondrial Biology,; 2013

Comité Organizador Argentino

Frataxin (FH) is a highly conserved protein through evolution that has been characterized in bacteria, yeast, humans and in Arabidopsis thaliana (AtFH). Although its precise function remains unclear, it has been proposed to participate as iron donor in Fe-S cluster assembly and it is involved in iron homeostasis, heme metabolism, ROS and REDOX control and protection against  oxidative damage. In eukaryotes, FH is a nuclear encoded protein with mitochondrial localization. The lack of FH produces mitochondrial dysfunction, high sensitivity to oxidative stress, growth defects and even letality. In maize, we identified two coding sequences homologous to AtFH, GRMZM2G062342 and GRMZM2G083755 (ZmFH42 and ZmFH55, respectively). In silico studies predict mainly a mitochondrial localization for the both proteins, but also a possible presence in chloroplast. We have cloned, purified and characterized both isoforms. Results show that at least one (ZmFH55) is a functional protein because it attenuates Fenton reaction. In addition, we evaluated its protective role against oxidative damage in the yeast model. Moreover, qPCR experiments showed that  both genes are expressed mainly in young maize tissues. Finally, fluorescence confocal microscopy studies on A. thaliana plants transformed with ZmFH isoforms fused to GFP suggest mainly a mitochondrial localization for both proteins, but also a chloroplastic location for ZmFH42, suggesting a dual localization in both organelles.