School of Systems Biomedical Science, Soongsil University, Seoul 156-743, Korea.
School of Systems Biomedical Science, Soongsil University, Seoul 156-743, Korea.
J Biol Chem. 2013 Sep 20;288(38):27172-27180. doi: 10.1074/jbc.M113.480277. Epub 2013 Aug 2.
In Escherichia coli, three cysteine desulfurases (IscS, SufS, and CsdA) initiate the delivery of sulfur for various biological processes such as the biogenesis of Fe-S clusters. The sulfur generated as persulfide on a cysteine residue of cysteine desulfurases is further transferred to Fe-S scaffolds (e.g. IscU) or to intermediate cysteine-containing sulfur acceptors (e.g. TusA, SufE, and CsdE) prior to its utilization. Here, we report the structures of CsdA and the CsdA-CsdE complex, which provide insight into the sulfur transfer mediated by the trans-persulfuration reaction. Analysis of the structures indicates that the conformational flexibility of the active cysteine loop in CsdE is essential for accepting the persulfide from the cysteine of CsdA. Additionally, CsdA and CsdE invoke a different binding mode than those of previously reported cysteine desulfurase (IscS) and sulfur acceptors (TusA and IscU). Moreover, the conservation of interaction-mediating residues between CsdA/SufS and CsdE/SufE further suggests that the SufS-SufE interface likely resembles that of CsdA and CsdE.
在大肠杆菌中，三种半胱氨酸脱硫酶（IscS、SufS 和 CsdA）启动硫的输送，用于各种生物过程，如 Fe-S 簇的生物发生。半胱氨酸脱硫酶的半胱氨酸残基上生成的过硫化物进一步被转移到 Fe-S 支架（例如 IscU）或中间含半胱氨酸的硫受体（例如 TusA、SufE 和 CsdE），然后再利用。在这里，我们报告了 CsdA 和 CsdA-CsdE 复合物的结构，这为通过反式过硫化反应介导的硫转移提供了深入了解。结构分析表明，CsdE 中活性半胱氨酸环的构象灵活性对于接受来自 CsdA 的半胱氨酸的过硫化物至关重要。此外，CsdA 和 CsdE 采用的结合模式与先前报道的半胱氨酸脱硫酶（IscS）和硫受体（TusA 和 IscU）不同。此外，CsdA/SufS 和 CsdE/SufE 之间介导相互作用的残基的保守性进一步表明，SufS-SufE 界面可能类似于 CsdA 和 CsdE。
