Human Tdp1 cleaves a broad spectrum of substrates, including phosphoamide linkages
Human Tdp1 cleaves a broad spectrum of substrates, including phosphoamide linkages
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DOI：
10.1074/jbc.m508898200
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发表时间：
2005-10-28
影响因子：
4.8
通讯作者：
Champoux, JJ
中科院分区：
文献类型：
--
作者：
Interthal, H;Chen, HJ;Champoux, JJ
人酪氨酰-DNA磷酸二酯酶（Tdp 1）水解DNA 3'末端和酪氨酰部分之间的磷酸二酯键。在真核细胞中，这种类型的连接被发现在停滞的拓扑异构酶I-DNA共价复合物中，并且Tdp 1已经被牵连在体内修复这种复合物中。我们在这里证实，Tdp 1催化循环涉及一个共价反应中间体，其中组氨酸残基通过磷酰胺键连接到DNA 3 '-磷酸。最令人惊讶的是，这种连接可以被Tdp 1水解，并且与需要修饰以成为Tdp 1的有效底物的拓扑异构酶I-DNA复合物不同，Tdp 1的天然形式可以从DNA中去除。脊髓小脑共济失调伴轴突神经病神经退行性疾病是由Tdp 1的H493 R突变形式引起的，其显示酶活性降低并积累Tdp 1-DNA共价中间体。野生型Tdp 1从DNA中去除停滞突变蛋白的能力可能解释了脊髓小脑共济失调伴轴突神经病的隐性本质。除了对磷酸酪氨酸和磷酸组氨酸底物的活性外，Tdp 1还具有有限的DNA和RNA 3 '-外切核酸酶活性，其中从底物的3'-羟基末端去除单个核苷。此外，Tdp 1还从DNA中去除3'脱碱基位点和人工3'-生物素加合物。结合早期的数据显示Tdp 1可以使用3 '-磷酸乙醇酸作为底物，这些数据表明Tdp 1可能在DNA修复过程中从DNA中去除各种3'加合物。
Human tyrosyl-DNA phosphodiesterase (Tdp1) hydrolyzes the phosphodiester bond between a DNA 3' end and a tyrosyl moiety. In eukaryotic cells, this type of linkage is found in stalled topoisomerase I-DNA covalent complexes, and Tdp1 has been implicated in the repair of such complexes in vivo. We confirm here that the Tdp1 catalytic cycle involves a covalent reaction intermediate in which a histidine residue is connected to a DNA 3'-phosphate through a phosphoamide linkage. Most surprisingly, this linkage can be hydrolyzed by Tdp1, and unlike a topoisomerase I-DNA complex, which requires modification to be an efficient substrate for Tdp1, the native form of Tdp1 can be removed from the DNA. The spinocerebellar ataxia with axonal neuropathy neurodegenerative disease is caused by the H493R mutant form of Tdp1, which shows reduced enzymatic activity and accumulates the Tdp1-DNA covalent intermediate. The ability of wild type Tdp1 to remove the stalled mutant protein from the DNA likely explains the recessive nature of spinocerebellar ataxia with axonal neuropathy. In addition to its activity on phosphotyrosine and phosphohistidine substrates, Tdp1 also possesses a limited DNA and RNA 3'-exonuclease activity in which a single nucleoside is removed from the 3'-hydroxyl end of the substrate. Furthermore, Tdp1 also removes a 3' abasic site and an artificial 3'-biotin adduct from the DNA. In combination with earlier data showing that Tdp1 can use 3'-phosphoglycolate as a substrate, these data suggest that Tdp1 may function to remove a variety of 3' adducts from DNA during DNA repair.