Mutations at serine 37 in mouse guanylate kinase confer resistance to 6-thioguanine.
Mutations at serine 37 in mouse guanylate kinase confer resistance to 6-thioguanine.
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小鼠鸟苷酸激酶中丝氨酸 37 的突变赋予对 6-硫鸟嘌呤的抗性。
DOI：
10.1093/protein/gzn078
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发表时间：
2009
期刊：
影响因子：
--
通讯作者：
Black,MargaretE
中科院分区：
文献类型：
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作者：
Ardiani,Andressa;Goyke,Amanda;Black,MargaretE
鸟苷酸激酶(GMK)是一种重要的核苷一磷酸激酶，它催化鸟嘌呤一磷酸(GMP)和dGMP的磷酸化，分别产生GDP和dGDP，这两种产物是核苷酸合成的重要前体。GMK还负责激活6-硫代鸟嘌呤(6-TG)，这是一种广泛用于治疗白血病的化疗药物。已经报道了几种6-甘油三酯耐药的机制，但这些机制不能解释耐药细胞的子集。我们认为GMK基因突变可能导致耐药。因为细胞的存活需要一个有功能的GMK，所以导致6-TG耐药的突变必须保持对GMP的活性。我们报道了小鼠GMK中丝氨酸37(S37)位的三个氨基酸替换，它们通过给予条件GMK缺陷的大肠杆菌在酶分析中的遗传互补来显示对GMP的活性。当6-TG被纳入互补研究时，表达野生型GMK的细胞是敏感的，而所有被检测的S37突变株都能够有效地区分6-TG并表现出耐药表型。三种S37突变酶对临床相关浓度的6-TGMP的活性是检测不到的。因此，GMK的突变代表了一种以前未描述的6-甘油三酯耐药机制。
Guanylate kinase (GMK) is an essential nucleoside monophosphate kinase that catalyzes the phosphorylation of guanine-monophosphate (GMP) and dGMP to yield GDP and dGDP, respectively, important precursors for nucleotide synthesis. GMK is also responsible for the activation of 6-thioguanine (6-TG), a drug widely used as chemotherapeutic agent to treat leukemia. Several mechanisms of resistance to 6-TG have been reported but a subset of drug resistant cells cannot be explained by these mechanisms. We propose that mutations in GMK could result in drug resistance. Because cells require the presence of a functional GMK for viability, mutations that arise that lead to 6-TG resistance must retain activity toward GMP. We report three amino acid substitutions at serine 37 (S37) in mouse GMK that display activity toward GMP by conferring genetic complementation to a conditional GMK-deficientEscherichia coliand in enzyme assays. When 6-TG is included in complementation studies, cells expressing wild-type GMK are sensitive whereas all S37 mutants examined are able to effectively discriminate against 6-TG and display a drug resistance phenotype. Activity of the three S37 mutant enzymes toward clinically relevant concentrations of 6-TGMP is undetectable. Mutations in GMK, therefore, represent a previously undescribed mechanism for 6-TG resistance.