嗜酸氧化亚铁硫杆菌ISC铁硫簇系统的合成

Biogenesis of iron sulfur cluster of Acidithiobacillus ferrooxidans

【目的】铁硫簇是最古老的一种氧化还原中心,它普遍存在于所有生命体内,在光合作用、呼吸作用和固氮作用这三个地球生命最基本的代谢途径中扮演着重要的角色。【方法】以嗜酸氧化亚铁硫杆菌(A.ferrooxidans ATCC 23270)基因组为模板,克隆表达其ISC铁硫簇组装的3个核心蛋白,IscS(半胱氨酸脱硫酶蛋白)、IscU(支架蛋白)和IscA(铁供体蛋白)。【结果】研究发现IscS能催化半胱氨酸脱硫,为铁硫簇的组装提供硫,支架蛋白IscU不具备结合铁的能力,IscA具有较强的铁结合能力。【结论】铁硫簇体外组装证明Fe-IscA在体外能将结合的铁传递给IscS,并在IscU上进行铁硫簇的组装。

[Objective] Iron sulfur cluster are one of the most ancient and ubiquitous redox centre in almost all living organism and play an important role in photosynthesis, respiration and nitrogen fixation. [Methods] In this study, three key proteins （IscS, IscU, IscA） involved in iron sulfur cluster assembly from A. ferrooxidans ATCC 23270 was cloned and expressed in Escherichia coli. [Results] IscS is a cysteine desulfurase, IscU is a scaffold protein, IscA hasstrong iron binding activity which acts an iron chaperon. [Conclusion] The Fe-IscA can pro- vide iron for the assembly of transient iron sulfur cluster in IscU in the presence of IscS and L-cysteine in vitro.