A role for DNA polymerase in the specificity of nucleotide incorporation opposite N-acetyl-2-aminofluorene adducts.
A role for DNA polymerase in the specificity of nucleotide incorporation opposite N-acetyl-2-aminofluorene adducts.
复制标题
DNA 聚合酶在与 N-乙酰基-2-氨基芴加合物相反的核苷酸掺入特异性中的作用。
DOI：
10.1016/0022-2836(84)90239-0
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发表时间：
1984
影响因子：
5.6
通讯作者：
Strauss,BS
中科院分区：
文献类型：
--
作者：
Rabkin,SD;Strauss,BS
大肠杆菌DNA聚合酶I （Klenow片段）、小牛胸腺细胞和人淋巴瘤细胞的DNA聚合酶α、小牛胸腺细胞和诺维科夫肝癌细胞的DNA聚合酶β都能在DNA中结合鸟嘌呤-8-酰基乙酰基-2-氨基芴。当Mg2+为二价阳离子时，聚合酶将dCTP与一些AAF-dG病变相结合。Mg2+取代Mn2+可拓宽插入的特异性：E。coliDNA聚合酶I （Klenow片段）也插入A，并插入特定位点G或T；DNA聚合酶α可以插入A和C优先结合到G和t的四种dNTPs中的任何一种，聚合酶β具有特异性，即使在Mn2+存在的情况下也主要插入C。在病灶对面添加dATP的km。Mn2+存在时，dNMPs增加了与AAF-dG相反的核苷酸的插入，并增加了在Mn2+存在时发生结合的位点的速率和数量。dNTPαS和recA蛋白只增加了C的插入。我们认为dCTP的加入反映了与AAF-脱氧鸟嘌呤在反构象中的正常碱基配对，而其他核苷酸（包括一些C）的插入反映了与AAF-脱氧鸟嘌呤在其首选合构象中相反的插入。DNA聚合酶在确定损伤终止DNA合成的插入特异性中起作用的事实表明，碱基置换诱变蛋白的谱可能反映了包括参与旁路合成的聚合酶在内的蛋白质组分的特性。
Escherichia coliDNA polymerase I (Klenow fragment), DNA polymerase α from both calf thymus and human lymphoma cells and DNA polymerase β from calf thymus and Novikoff hepatoma cells can incorporate nucleotides oppositeN-guanin-8-yl-acetyl-2-aminofluorene in DNA. The polymerases incorporate dCTP opposite some AAF-dG§lesions when Mg2+is the divalent cation. Substitution of Mn2+for Mg2+broadens the specificity of insertion:E. coliDNA polymerase I (Klenow fragment) also inserts A, and at specific sites G or T; DNA polymerase α inserts any of the four dNTPs with A and C incorporated preferentially to G and T. Polymerase β is specific, inserting mainly C even in the presence of Mn2+. TheKmfor addition of dATP opposite a lesion byE. colipolymerase I (Klenow fragment) in the presence of Mn2+is about 0.5 mm. dNMPs increase the insertion of nucleotides opposite AAF-dG in the presence of Mg2+and increase both the rate and number of sites at which incorporation occurs in the presence of Mn2+. dNTPαS and recA protein increase only the insertion of C.We suppose that the incorporation of dCTP reflects normal base-pairing with the AAF-deoxyguanine in theanticonformation, whereas insertion of the other nucleotides (including some of the C) reflects insertion opposite the AAF adduct in its preferredsynconformation. The fact that the DNA polymerase plays a role in determining the specificity of insertion opposite a lesion terminating DNA synthesis suggests that the spectrum of base substitution mutagenesis seenin vivomay reflect the properties of the protein components, including the polymerase, involved in bypass synthesis.