Jac1, a mitochondrial J-type chaperone, is involved in the biogenesis of Fe/S clusters in Saccharomyces cerevisiae

A minor Hsp70 chaperone of the mitochondrial matrix of Saccharomyces cerevi siae, Ssq1, is involved in the formation or repair of Fe/S clusters and/or mitochondrial iron metabolism. Here, we report evidence that Jac1, a J-type chaperone of the mitochondrial matrix, is the partner of Ssq1 in this proc ess. Reduced activity of Jac1 results in a decrease in activity of Fe/S con taining mitochondrial proteins and an accumulation of iron in mitochondria, Fe/S enzyme activities remain low in both jac1 and ssq1 mutant mitochondri a even if normal mitochondrial iron levels are maintained. Therefore, the l ow activities observed are not solely due to oxidative damage caused by exc ess iron. Rather, these molecular chaperones likely play a direct role in t he normal assembly process of Fe/S clusters.