Department of Chemistry and Biochemistry, University of Alabama, 250 Hackberry Lane, Tuscaloosa, AL 35401, USA.
Acta Crystallogr D Struct Biol. 2020 Mar 1;76(Pt 3):291-301. doi: 10.1107/S2059798320000790. Epub 2020 Feb 25.
Cysteine serves as the sulfur source for the biosynthesis of Fe-S clusters and thio-cofactors, molecules that are required for core metabolic processes in all organisms. Therefore, cysteine desulfurases, which mobilize sulfur for its incorporation into thio-cofactors by cleaving the C-S bond of cysteine, are ubiquitous in nature. SufS, a type 2 cysteine desulfurase that is present in plants and microorganisms, mobilizes sulfur from cysteine to the transpersulfurase SufE to initiate Fe-S biosynthesis. Here, a 1.5 Å resolution X-ray crystal structure of the Escherichia coli SufS homodimer is reported which adopts a state in which the two monomers are rotated relative to their resting state, displacing a β-hairpin from its typical position blocking transpersulfurase access to the SufS active site. A global structure and sequence analysis of SufS family members indicates that the active-site β-hairpin is likely to require adjacent structural elements to function as a β-latch regulating access to the SufS active site.
半胱氨酸是生物体内铁硫簇和硫辅因子生物合成的硫源，这些分子是所有生物核心代谢过程所必需的。因此，半胱氨酸脱硫酶在自然界中普遍存在，它们通过切断半胱氨酸的 C-S 键将硫转移到硫辅因子中。SufS 是一种存在于植物和微生物中的 2 型半胱氨酸脱硫酶，它将硫从半胱氨酸转移到转硫酶 SufE 上，从而启动 Fe-S 生物合成。本文报道了大肠杆菌 SufS 同源二聚体的 1.5 Å 分辨率 X 射线晶体结构，该结构采用了一种状态，其中两个单体相对于它们的静止状态旋转，将 β-发夹从其典型位置移动，从而阻止转硫酶进入 SufS 活性位点。对 SufS 家族成员的全局结构和序列分析表明，活性位点的 β-发夹可能需要相邻的结构元件作为 β-闩锁来调节进入 SufS 活性位点的通道。
