Cysteine dioxygenase (CDO) plays an essential role in sulfur metabolism by regulating homeostatic levels of cysteine. Human CDO contains a post-translationally generated Cys93âTyr157 cross-linked cofactor. Here, we investigated this CysâTyr cross-linking by incorporating unnatural tyrosines in place of Tyr157 via a genetic method. The catalytically active variants were obtained with a thioether bond between Cys93 and the halogen-substituted Tyr157, and we determined the crystal structures of both wild-type and engineered CDO variants in the purely uncross-linked form and with a mature cofactor. Along with mass spectrometry and 19F NMR, these data indicated that the enzyme could catalyze oxidative CâF or CâCl bond cleavage, resulting in a substantial conformational change of both Cys93 and Tyr157 during cofactor assembly. These findings provide insights into the mechanism of CysâTyr cofactor biogenesis and may aid the development of bioinspired aromatic carbonâhalogen bond activation. Engineered variants of cysteine dioxygenase containing a halogen-substituted tyrosine analog provide insights into the process of CysâTyr cross-link formation and indicate that the enzyme can catalyze oxidative cleavage of a carbonâfluorine bond.
半胱
氨酸二氧化酶(CDO)在
硫代谢中发挥着重要作用,通过调节半胱
氨酸的稳态
水平。人类的CDO含有一种后转译生成的Cys93–Tyr157交联辅因子。在此,我们通过遗传方法将非天然
酪氨酸替换为Tyr157,研究了这种Cys–Tyr交联。我们获得了具有Cys93与卤素取代的Tyr157之间的
硫醚键的催化活性变体,并确定了野生型和工程化CDO变体在纯无交联形式和具有成熟辅因子的形式下的晶体结构。结合质谱和19F NMR,这些数据表明,酶能够催化碳–
氟或碳–
氯键的氧化断裂,导致在辅因子组装过程中Cys93和Tyr157发生显著的构象变化。这些发现为Cys–Tyr辅因子
生物生成的机制提供了见解,并可能有助于开发仿生的芳香碳–卤素键活化。含有卤素取代
酪氨酸类似物的工程化半胱
氨酸二氧化酶变体提供了对Cys–Tyr交联形成过程的见解,并表明该酶能够催化碳–
氟键的氧化断裂。