Increased Expression of Genes Involved in Fe-S Cluster Biosynthesis in Atfh Deficient Plants

Iron-Sulfur cluster are cofactors of proteins involved in central biochemical pathways and their assembly, and the maturation Fe-S proteins requires complex cellular machineries. The are three different systems for the biogenesis of bacterial Fe-S proteins: The NIF system for specific maturation of nitrogenase in azototrophic bacteria; and the ISC assembly and SUF system for the generation of housekeeping Fe-S proteins under normal and oxidative stress conditions, respectively. In eukaryotes, mitochondria are the primary site of cluster formation of most Fe-S proteins. Assembly of the Fe-S cluster is mediated by ISC machinery (Iron Sulphate Cluster assembly). In our laboratory we have characterized different genes and proteins that are postulated to be involved in the Fe-S cluster biosynthesis in Arabidopsis thaliana. AtNfs1 (Cysteine desulphurase, sulphur donor), AtFH (frataxin, iron donor); Isu1 (Scaffold protein); HscB (co-chaperone) and HscA (heat Shock protein). In this work we evaluate the effect of the deficiency of AtFH in the expression of the genes mentioned above. We measured the transcript level of these genes by QPCR in mutants plants of A.thaliana, Knock down(atfh-1) and antisense (as-atfh). All analized transcripts were increased (2 to 8-fold). However, some iron-sulfur proteins such as aconitase or succinate deshidrogenase were decreased in its catalytic activity. Our results are in agreement with a role of frataxin in the biogenesis of Fe-S proteins in plants.