Trotter Valentine, Vinella Daniel, Loiseau Laurent, Ollagnier de Choudens Sandrine, Fontecave Marc, Barras Frédéric
Laboratoire de Chimie Bactérienne, UPR-CNRS 9043, IFR 88 Institut de Microbiologie de la Méditerranée, CNRS, 31 Chemin Joseph Aiguier, 13402 Marseille Cedex 20, France.
Mol Microbiol. 2009 Dec;74(6):1527-42. doi: 10.1111/j.1365-2958.2009.06954.x.
Cysteine desulphurases are primary sources of sulphur that can eventually be used for Fe/S biogenesis or thiolation of various cofactors and tRNA. Escherichia coli contains three such enzymes, IscS, SufS and CsdA. The importance of IscS and SufS in Fe/S biogenesis is well established. The physiological role of CsdA in contrast remains uncertain. We provide here additional evidences for a functional redundancy between the three cysteine desulphurases in vivo. In particular, we show that a deficiency in isoprenoid biosynthesis is the unique cause of the lethality of the iscS sufS mutant. Moreover, we show that CsdA is engaged in two separate sulphur transfer pathways. In one pathway, CsdA interacts functionally with SufE-SufBCD proteins to assist Fe/S biogenesis. In another pathway, CsdA interacts with CsdE and a newly discovered protein, which we called CsdL, resembling E1-like proteins found in ubiquitin-like modification systems. We propose this new pathway to allow synthesis of an as yet to be discovered thiolated compound.
半胱氨酸脱硫酶是硫的主要来源，最终可用于铁硫簇生物合成或各种辅因子及转运RNA的硫醇化。大肠杆菌含有三种此类酶，即IscS、SufS和CsdA。IscS和SufS在铁硫簇生物合成中的重要性已得到充分证实。相比之下，CsdA的生理作用仍不确定。我们在此提供了体内三种半胱氨酸脱硫酶功能冗余的更多证据。特别是，我们表明类异戊二烯生物合成缺陷是iscS sufS突变体致死性的唯一原因。此外，我们表明CsdA参与两条独立的硫转移途径。在一条途径中，CsdA与SufE-SufBCD蛋白在功能上相互作用以协助铁硫簇生物合成。在另一条途径中，CsdA与CsdE和一种新发现的蛋白相互作用，我们将其称为CsdL，它类似于泛素样修饰系统中发现的E1样蛋白。我们提出这条新途径可用于合成一种尚未发现的硫醇化化合物。
