Werner Syndrome Protein II . CHARACTERIZATION OF THE INTEGRAL 3 9 3 5 9 DNA EXONUCLEASE *
Werner Syndrome Protein II . CHARACTERIZATION OF THE INTEGRAL 3 9 3 5 9 DNA EXONUCLEASE *
复制标题
DOI：
--
复制
发表时间：
1998
期刊：
影响因子：
--
通讯作者：
A. Kamath-Loeb;Jiang-Cheng Shen;L. Loeb;M. Fry
中科院分区：
文献类型：
--
作者：
A. Kamath-Loeb;Jiang-Cheng Shen;L. Loeb;M. Fry
除了DNA解旋酶活性外，Werner综合征蛋白（WRN）还具有外切酶活性(Shen, j.c。， Gray, m.d, Kamath-Loeb, a.s., Fry， M, Oshima， J., and Loeb, l.a.（1998）。化学，273,34139 - 34144)。在这里，我们描述了几乎均匀的WRN外切酶的性质。WRN核酸外切酶水解部分DNA双链中的内嵌链，但不显著地消化单链DNA、钝端双链或部分双链的突出链。虽然DNA在没有三磷酸核苷的情况下被水解，但核酸酶的活性明显受到ATP、dATP或CTP的刺激。WRN核酸外切酶酶切3* 3 - 5*方向的DNA生成5*-dNMP产物，以3*-OH或3*-PO4基团终止的DNA链水解程度相似。与具有互补核苷酸的DNA链相比，具有单个3*末端错配的嵌入式DNA链被WRN更有效地水解，但该酶不能水解具有两个错配碱基末端的DNA链。WRN外切酶与已知哺乳动物DNA核酸酶的不同之处在于它与DNA解旋酶的共价结合、对内嵌DNA链的偏好、ATP的刺激、同样消化具有3*-OH或3*-PO4末端的DNA的能力，以及它优先消化具有单个3*末端错配的DNA。
In addition to its DNA helicase activity, Werner syndrome protein (WRN) also possesses an exonuclease activity (Shen, J.-C. , Gray, M. D., Kamath-Loeb, A. S., Fry, M., Oshima, J., and Loeb, L. A. (1998) J. Biol. Chem. 273, 34139–34144). Here we describe the properties of nearly homogeneous WRN exonuclease. WRN exonuclease hydrolyzes a recessed strand in a partial DNA duplex but does not significantly digest single-stranded DNA, blunt-ended duplex, or a protruding strand of a partial duplex. Although DNA is hydrolyzed in the absence of nucleoside triphosphates, nuclease activity is markedly stimulated by ATP, dATP, or CTP. WRN exonuclease digests DNA with a 3* 3 5* directionality to generate 5*-dNMP products, and DNA strands terminating with either a 3*-OH or 3*-PO4 group are hydrolyzed to similar extents. A recessed DNA strand with a single 3*-terminal mismatch is hydrolyzed more efficiently by WRN than one with a complementary nucleotide, but the enzyme fails to hydrolyze a DNA strand terminating with two mismatched bases. WRN exonuclease is distinguished from known mammalian DNA nucleases by its covalent association with a DNA helicase, preference for a recessed DNA strand, stimulation by ATP, ability to equally digest DNA with 3*-OH or 3*-PO4 termini, and its preferential digestion of DNA with a single 3*-terminal mismatch.