A single amino acid governs enhanced activity of DinB DNA polymerases on damaged templates
A single amino acid governs enhanced activity of DinB DNA polymerases on damaged templates
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DOI：
10.1038/nature04318
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发表时间：
2006-01-12
期刊：
影响因子：
64.8
通讯作者：
Walker, GC
中科院分区：
文献类型：
--
作者：
Jarosz, DF;Godoy, VG;Walker, GC
Y家族DNA聚合酶的转录合成（TLS）是DNA损伤耐受的主要机制（1）。此类TLS可能是准确的或容易出错的，因为它分别用于绕过DNA聚合酶h（XP-V或Rad 30）的环丁烷嘧啶二聚体或绕过DNA聚合酶V（UmuD 'C-2）的（6-4）TT光产物（2，3）。虽然DinB是唯一的Y家族DNA聚合酶保守的所有领域的生活，这种惊人的保守的生物学原理仍然是谜（4）。在这里，我们报告说，大肠杆菌dinB基因所需的一些DNA损伤剂，形成加合物在N-2-位置的脱氧鸟苷（dG）的抗性。我们表明，DinB（DNA聚合酶IV）催化一个这样的N-2-dG加合物（N-2-糠基-dG）的准确TLS，DinB和它的哺乳动物直向同源物，DNA聚合酶κ，插入脱氧胞苷（dC）相对于N-2-糠基-dG与10-15倍的催化能力比相对未受损的dG。我们还表明，突变一个单一的氨基酸，“空间门”残基DinB（Phe 13-->瓦尔）和它的古细菌同系物Dbh（Phe 12--> Ala），分离的能力，这些酶进行TLS N-2-dG加合物从他们的能力，复制一个未受损的模板。我们建议，DinB及其直系同源物是专门催化相对准确的TLS在一些N-2-dG加合物是无处不在的性质，病变旁路发生更有效地比合成未受损的DNA，这种特异性可以实现至少部分通过病变诱导的构象变化。
Translesion synthesis (TLS) by Y-family DNA polymerases is a chief mechanism of DNA damage tolerance(1). Such TLS can be accurate or error-prone, as it is for bypass of a cyclobutane pyrimidine dimer by DNA polymerase h (XP-V or Rad30) or bypass of a (6-4) TT photoproduct by DNA polymerase V (UmuD'C-2), respectively(2,3). Although DinB is the only Y-family DNA polymerase conserved among all domains of life, the biological rationale for this striking conservation has remained enigmatic(4). Here we report that the Escherichia coli dinB gene is required for resistance to some DNA-damaging agents that form adducts at the N-2-position of deoxyguanosine (dG). We show that DinB (DNA polymerase IV) catalyses accurate TLS over one such N-2-dG adduct (N-2-furfuryl-dG), and that DinB and its mammalian orthologue, DNA polymerase kappa, insert deoxycytidine (dC) opposite N-2-furfuryl-dG with 10-15-fold greater catalytic proficiency than opposite undamaged dG. We also show that mutating a single amino acid, the 'steric gate' residue of DinB (Phe13 --> Val) and that of its archaeal homologue Dbh (Phe12 --> Ala), separates the abilities of these enzymes to perform TLS over N-2-dG adducts from their abilities to replicate an undamaged template. We propose that DinB and its orthologues are specialized to catalyse relatively accurate TLS over some N-2-dG adducts that are ubiquitous in nature, that lesion bypass occurs more efficiently than synthesis on undamaged DNA, and that this specificity may be achieved at least in part through a lesion-induced conformational change.