Cleavage of single- and double-stranded DNAs containing an abasic residue by Escherichia coli exonuclease III (AP endonuclease VI)
Cleavage of single- and double-stranded DNAs containing an abasic residue by Escherichia coli exonuclease III (AP endonuclease VI)
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DOI：
10.1093/nar/24.22.4572
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发表时间：
1996-11-15
影响因子：
14.9
通讯作者：
Sekiguchi, J
中科院分区：
文献类型：
--
作者：
Shida, T;Noda, M;Sekiguchi, J
大肠杆菌外切核酸酶III（AP内切核酸酶VI）是一种DNA修复酶，可将磷酸二酯键5'水解至DNA中的脱碱基位点。为了研究该酶如何识别脱碱基位点，我们使用在序列中任何所需位置含有合成脱碱基位点的寡核苷酸，我们制备了含有脱碱基残基的寡核苷酸，例如2'-脱氧核糖基甲酰胺、2 '-脱氧核糖、1'，2 ′-二脱氧呋喃核糖或丙二醇。本研究中使用的含有脱碱基残基的双链体寡核苷酸在脱碱基位点的5'侧被核酸外切酶III切割，而不管与脱碱基位点相对和相邻的碱基的种类。此外，我们观察到酶切割在脱碱基位点的5'侧的含有脱碱基位点的单链寡核苷酸，这些结果表明，该酶可能主要识别在脱碱基位点形成的DNA口袋，外切核酸酶iii的色氨酸212残基的吲哚环可能插入到脱碱基位点。在催化位点附近的色氨酸在来自各种生物体的II型AP内切核酸酶中是保守的。
The Escherichia coli exonuclease III (AP endonuclease VI) is a DNA-repair enzyme that hydrolyzes the phosphodiester bond 5' to an abasic site in DNA, To study how the enzyme recognizes the abasic site, we used oligonucleotides containing a synthetic abasic site at any desired position in the sequence, we prepared oligonucleotides containing an abasic residue such as 2'-deoxyribosylformamide, 2'-deoxyribose, 1',2'-dideoxy ribofuranose or propanediol. Duplex oligonucleotides containing an abasic residue used in this study were cleaved on the 5' side of the abasic site by exonuclease III in spite of the Varieties of the bases opposite and adjacent to the abasic site, In addition, we observed that the enzyme cleaved single-stranded oligonucleotides containing an abasic site on the 5' side of the abasic site, These findings suggest that the enzyme may principally recognize the DNA-pocket formed at an abasic site, The indole ring of the tryptophan 212 residue of the exonuclease iii is probably intercalated to the abasic site. The tryptophan in the vicinity of the catalytic site is conserved in the type II AP endonuclease from various organisms.