Hu Rong-Gui, Sheng Jun, Qi Xin, Xu Zhenming, Takahashi Terry T, Varshavsky Alexander
Division of Biology, California Institute of Technology, Pasadena, California 91125, USA.
Nature. 2005 Oct 13;437(7061):981-6. doi: 10.1038/nature04027.
The conjugation of arginine to proteins is a part of the N-end rule pathway of protein degradation. Three amino (N)-terminal residues--aspartate, glutamate and cysteine--are arginylated by ATE1-encoded arginyl-transferases. Here we report that oxidation of N-terminal cysteine is essential for its arginylation. The in vivo oxidation of N-terminal cysteine, before its arginylation, is shown to require nitric oxide. We reconstituted this process in vitro as well. The levels of regulatory proteins bearing N-terminal cysteine, such as RGS4, RGS5 and RGS16, are greatly increased in mouse ATE1-/- embryos, which lack arginylation. Stabilization of these proteins, the first physiological substrates of mammalian N-end rule pathway, may underlie cardiovascular defects in ATE1-/- embryos. Our findings identify the N-end rule pathway as a new nitric oxide sensor that functions through its ability to destroy specific regulatory proteins bearing N-terminal cysteine, at rates controlled by nitric oxide and apparently by oxygen as well.
精氨酸与蛋白质的缀合是蛋白质降解的N端规则途径的一部分。三种氨基（N）末端残基——天冬氨酸、谷氨酸和半胱氨酸——被ATE1编码的精氨酰转移酶进行精氨酰化。在此，我们报告N末端半胱氨酸的氧化对其精氨酰化至关重要。结果表明，N末端半胱氨酸在精氨酰化之前的体内氧化需要一氧化氮。我们也在体外重建了这一过程。在缺乏精氨酰化的小鼠ATE1-/-胚胎中，带有N末端半胱氨酸的调节蛋白（如RGS4、RGS5和RGS16）的水平大幅增加。这些蛋白质作为哺乳动物N端规则途径的首批生理底物，其稳定性增加可能是ATE1-/-胚胎心血管缺陷的基础。我们的研究结果确定N端规则途径是一种新的一氧化氮传感器，它通过以一氧化氮以及显然还有氧气控制的速率破坏带有N末端半胱氨酸的特定调节蛋白的能力来发挥作用。
