Biogenesis of Fe-S and heme-containing proteins in plants

DIEGO FABIAN GOMEZ CASATI

Puerto Madryn

Congreso; XLVI Reunion SAIB; 2010

SAIB

Iron-sulfur and hemeproteins are involved in a wide variety of cellular processes such as respiration, photosynthesis and regulation of gene expression. The assembly of Fe-S and heme groups into polypeptides has become an area of intense research. Particularly, the synthesis of Fe-S proteins involved complex cellular machineries. Many of the genes are conserved in bacteria, yeasts, mammals and plants. We recently characterized mtHsp70-1 and 2, Isu1, HscB, AtNfs1 and AtFH, six mitochondrial Arabidopsis genes homologous to others that participate in yeast and mammals Fe-S assembly. We found that AtFH interacts and modulates AtNfs1 catalytic activity, suggesting the involvement of frataxin in early steps of Fe-S cluster formation. AtFH deficiency down-regulates AtNfs1 expression and other genes involved in Fe-S and heme synthesis. We also found an alteration in the activity of different mitochondrial and chloroplastic Fe-S proteins and hemeproteins such as catalase. The results indicate that AtFH, besides their role in protecting bioavailable iron within mitochondria and the synthesis of Fe-S groups, also plays a role in the biogenesis of heme group. Our data substantiate the hypothesis that AtFH would have a major role in heme production as an “iron chaperone” for ferrochelatase also is involved in the biogenesis of plant hemeproteins.