The Thioredoxin System Reduces Protein Persulfide Intermediates Formed during the Synthesis of Thio-Cofactors in Bacillus subtilis.

The biosynthesis of Fe-S clusters and other thio-cofactors requires the participation of redox agents. A shared feature in these pathways is the formation of transient protein persulfides, which are susceptible to reduction by artificial reducing agents commonly used in reactions in vitro. These agents modulate the reactivity and catalytic efficiency of biosynthetic reactions and, in some cases, skew the enzymes' kinetic behavior, bypassing sulfur acceptors known to be critical for the functionality of these pathways in vivo.

Protected sulfur transfer reactions by the Escherichia coli Suf system.

The first step in sulfur mobilization for the biosynthesis of Fe-S clusters under oxidative stress and iron starvation in Escherichia coli involves a cysteine desulfurase SufS. Its catalytic reactivity is dependent on the presence of a sulfur acceptor protein, SufE, which acts as the preferred substrate for this enzyme. Kinetic analysis of the cysteine:SufE sulfurtransferase reaction of the E.