Lin A L, Elford H L
J Biol Chem. 1980 Sep 25;255(18):8523-8.
Adenosine deaminase (adenosine aminohydrolase, EC 3.5.4.4)-deficient patients recently were found to have abnormally high levels of dATP, a negative allosteric effector of ribonucleotide reductase (ribonucleoside-diphosphate reductase, 2'-deoxyribonucleoside-diphosphate:oxidized thioredoxin 2'-oxidoreductase, EC 1.17.4.1). Therefore it was proposed that the immunodeficiency associated with adenosine deaminase deficiency is mediated through inhibition of ribonucleotide reductase and hence DNA replication. HeLa cells, treated with an adenosine deaminase inhibitor, erythro-9(2-hydroxy-3-nonyl)adenine, and deoxyadenosine to mimic the adenosine deaminase-deficient state, were monitored to determine directly the effects on ribonucleotide reductase activity and levels. A low concentration of erythro-9-(2-hydroxy-3-nonyl)adenine, which did not inhibit cell growth, nevertheless retarded the cells in G2 + M phase of the cell cycle and increased reductase activity. Reductase activity was also elevated in cells treated with a low level of deoxyadenosine which did not affect the cell cycle or cell growth. However, ribonucleotide reductase activity was reduced to one-half of the control value in cells treated with either enough deoxyadenosine to inhibit cell growth or with a combination of erythro-9(2-hydroxy-3-nonyl)adenine and deoxyadenosine, each at concentrations which individually do not inhibit cell growth. Removal of deoxynucleotides, particularly dATP, from these extracts increased ribonucleotide reductase activity to several-fold higher than control values. The reduced activity of ribonucleotide reductase in the simulated adenosine deaminase-deficient HeLa cells provides direct evidence for the thesis that adenosine deaminase deficiency disease is mediated through elevated levels of dATP which inhibit ribonucleotide reductase. In addition, the cell cycle patterns and ribonucleotide reductase levels suggest that the regulatory substance(s) that controls the level of ribonucleotide reductase is not operative until the late S or G2 phase of the cell cycle.
最近发现腺苷脱氨酶（腺苷氨基水解酶，EC 3.5.4.4）缺陷患者的dATP水平异常升高，dATP是核糖核苷酸还原酶（核糖核苷二磷酸还原酶，2'-脱氧核糖核苷二磷酸：氧化型硫氧还蛋白2'-氧化还原酶，EC 1.17.4.1）的负别构效应物。因此有人提出，与腺苷脱氨酶缺陷相关的免疫缺陷是通过抑制核糖核苷酸还原酶进而抑制DNA复制来介导的。用腺苷脱氨酶抑制剂erythro-9(2-羟基-3-壬基)腺嘌呤和脱氧腺苷处理HeLa细胞以模拟腺苷脱氨酶缺陷状态，监测其对核糖核苷酸还原酶活性和水平的直接影响。低浓度的erythro-9-(2-羟基-3-壬基)腺嘌呤不抑制细胞生长，但会使细胞在细胞周期的G2 + M期受阻并增加还原酶活性。用低水平脱氧腺苷处理的细胞中还原酶活性也升高，且这并不影响细胞周期或细胞生长。然而，在用足以抑制细胞生长的脱氧腺苷处理的细胞中，或在用erythro-9(2-羟基-3-壬基)腺嘌呤和脱氧腺苷组合处理的细胞中（每种物质单独使用时的浓度均不抑制细胞生长），核糖核苷酸还原酶活性降至对照值的一半。从这些提取物中去除脱氧核苷酸，特别是dATP，可使核糖核苷酸还原酶活性增加至比对照值高几倍。在模拟腺苷脱氨酶缺陷的HeLa细胞中核糖核苷酸还原酶活性降低，为腺苷脱氨酶缺乏症是通过升高的dATP水平抑制核糖核苷酸还原酶来介导这一论点提供了直接证据。此外，细胞周期模式和核糖核苷酸还原酶水平表明，控制核糖核苷酸还原酶水平的调节物质在细胞周期的S期晚期或G2期才起作用。
