Arnaoutov Alexei, Dasso Mary
Laboratory of Gene Regulation and Development, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA.
Science. 2014 Sep 19;345(6203):1512-5. doi: 10.1126/science.1251550.
Ribonucleotide reductase (RNR) supplies the balanced pools of deoxynucleotide triphosphates (dNTPs) necessary for DNA replication and maintenance of genomic integrity. RNR is subject to allosteric regulatory mechanisms in all eukaryotes, as well as to control by small protein inhibitors Sml1p and Spd1p in budding and fission yeast, respectively. Here, we show that the metazoan protein IRBIT forms a deoxyadenosine triphosphate (dATP)-dependent complex with RNR, which stabilizes dATP in the activity site of RNR and thus inhibits the enzyme. Formation of the RNR-IRBIT complex is regulated through phosphorylation of IRBIT, and ablation of IRBIT expression in HeLa cells causes imbalanced dNTP pools and altered cell cycle progression. We demonstrate a mechanism for RNR regulation in higher eukaryotes that acts by enhancing allosteric RNR inhibition by dATP.
核糖核苷酸还原酶（RNR）提供DNA复制和维持基因组完整性所需的平衡的脱氧核苷酸三磷酸（dNTP）库。在所有真核生物中，RNR都受到变构调节机制的调控，在芽殖酵母和裂殖酵母中，分别受到小蛋白抑制剂Sml1p和Spd1p的控制。在这里，我们表明后生动物蛋白IRBIT与RNR形成一种依赖于三磷酸脱氧腺苷（dATP）的复合物，该复合物在RNR的活性位点稳定dATP，从而抑制该酶。RNR-IRBIT复合物的形成通过IRBIT的磷酸化来调节，在HeLa细胞中敲除IRBIT表达会导致dNTP库失衡和细胞周期进程改变。我们证明了高等真核生物中RNR的一种调节机制，该机制通过增强dATP对变构RNR的抑制作用来发挥作用。
