Mechanism of deoxyadenosine-induced catabolism of adenine ribonucleotides in adenosine deaminase-inhibited human T lymphoblastoid cells.
Mechanism of deoxyadenosine-induced catabolism of adenine ribonucleotides in adenosine deaminase-inhibited human T lymphoblastoid cells.
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腺苷脱氨酶抑制的人 T 淋巴母细胞中脱氧腺苷诱导腺嘌呤核糖核苷酸分解代谢的机制。
DOI：
10.1073/pnas.79.8.2673
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发表时间：
1982
影响因子：
11.1
通讯作者：
Hershfield,MS
中科院分区：
文献类型：
--
作者：
Bagnara,AS;Hershfield,MS
Loss of ATP accompanying accumulation of dATP has recently been reported to occur in the erythrocytes and lymphoblasts of patients with T lymphocytic leukemia during treatment with deoxycoformycin, an inhibitor of adenosine deaminase (adenosine aminohydrolase, EC 3.5.4.4) that causes the accumulation of deoxyadenosine. We have studied the mechanisms responsible for adenine ribonucleotide depletion in cultured human CEM T lymphoblastoid cells treated with deoxycoformycin and deoxyadenosine. Accumulation of dATP was accompanied by depletion of total soluble adenine ribonucleotides without change in the adenylate energy charge, by the route ATP → AMP → IMP → inosine → hypoxanthine; conversion of IMP to AMP andde novopurine synthesis were inhibited in these cells. ATP degradation did not occur in a mutant of CEM that was incapable of phosphorylating deoxyadenosine, or in a B cell line with very limited ability to accumulate dATP. We found that dATP and ATP were both able to stimulate markedly the deamination of AMP by lymphoblast AMP deaminase; dAMP was a poor substrate for this enzyme (Km= 2.4 mM, vs. 0.4 mM for AMP). Similarly, dATP as well as ATP caused marked activation of IMP dephosphorylation by a lymphoblast cytoplasmic nucleotidase. Inhibition of intracellular AMP deaminase with coformycin prevented degradation of adenine ribonucleotides without affecting dATP accumulation. We propose that ATP-dependent phosphorylation of deoxyadenosine generates ADP and AMP. Simultaneously, dATP accumulation stimulates deamination of AMP, but not dAMP, and the dephosphorylation of IMP to inosine. Coupling of AMP degradation to ATP utilization in deoxyadenosine phosphorylation maintains the adenylate energy charge despite net depletion of cellular ATP.
