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首页> 外文期刊>Biochemistry >The Thioredoxin System Reduces Protein Persulfide Intermediates Formed during the Synthesis of Thio-Cofactors in Bacillus subtilis
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The Thioredoxin System Reduces Protein Persulfide Intermediates Formed during the Synthesis of Thio-Cofactors in Bacillus subtilis

机译：硫醚素系统减少了在枯草芽孢杆菌合成期间形成的蛋白质三硫化物中间体

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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. Here, we provide kinetic evidence for the selective reactivity of the Bacillus subtilis Trx (thioredoxin) system toward protein-bound persulfide intermediates. Our results demonstrate that the redox flux of the Trx system modulates the rate of sulfide production in cysteine desulfurase assays. Likewise, the activity of the Trx system is dependent on the rate of persulfide formation, suggesting the occurrence of coupled reaction schemes between both enzymatic systems in vitro. Inactivation of TrxA (thioredoxin) or TrxR (thioredoxin reductase) impairs the activity of Fe-S enzymes in B. subtilis, indicating the involvement of the Trx system in Fe-S cluster metabolism. Surprisingly, biochemical characterization of TrxA reveals that this enzyme is able to coordinate Fe-S species, resulting in the loss of its reductase activity. The inactivation of TrxA through the coordination of a labile cluster, combined with its proposed role as a physiological reducing agent in sulfur transfer pathways, suggests a model for redox regulation. These findings provide a potential link between redox regulation and Fe-S metabolism.
机译：Fe-S簇的生物合成和其他硫型辅因子需要氧化还原剂的参与。这些途径中的共同特征是形成瞬时蛋白质过硫化物，其易于通过在体外反应中通常用于反应的人工还原剂来影响。这些药剂调节生物合成反应的反应性和催化效率，并且在一些情况下倾斜酶的动力学行为，绕过硫磺受体，以为体内这些途径的功能至关重要。在这里，我们为枯草芽孢杆菌TRX（硫嗪）系统的选择性反应性提供给蛋白质结合的过硫化的中间体的动力学证据。我们的结果表明，TRX系统的氧化还原通量调节半胱氨酸脱硫酶测定中的硫化物产生速率。同样，TRX系统的活性取决于过硫化物形成的速率，表明在体外酶系统之间的偶联反应方案发生。 TRXA（硫氧胺）或TRXR（硫氧嗪还原酶）灭活损害B.枯草芽孢杆菌中Fe-S酶的活性，表明TRX系统在Fe-S簇代谢中的参与。令人惊讶的是，TRXA的生化表征显示，该酶能够协调Fe-S物种，导致其还原酶活性丧失。 TRXA通过不稳定簇的协调灭活，与其在硫转移途径中作为生理还原剂的拟议作用相结合，表明了氧化还原调控的模型。这些发现提供了氧化还原调控和Fe-S代谢之间的潜在联系。

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