Up-regulation of the fidelity of human DNA polymerase λ by its non-enzymatic proline-rich domain
Up-regulation of the fidelity of human DNA polymerase λ by its non-enzymatic proline-rich domain
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DOI：
10.1074/jbc.m601178200
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发表时间：
2006-07-14
影响因子：
4.8
通讯作者：
Suo, Zucai
中科院分区：
文献类型：
--
作者：
Fiala, Kevin A.;Duym, Wade W.;Suo, Zucai
DNA修复途径是维持基因组稳定性的关键。DNA聚合酶β在体内碱基切除修复中起着关键作用。DNA聚合酶lambda是最近发现的DNA聚合酶β的X家族同源基因，被认为是参与碱基切除修复的第二个聚合酶。全长DNA聚合酶lambda由三个结构域组成：C端DNA聚合酶β结构域，N端BRCA1 C端结构域，以及先前未描述的富含Pro的结构域。引人注目的是，稳态前的动力学分析显示，尽管人类DNA聚合酶lambda与人类DNA聚合酶β具有几乎相同的保真度，但仅C末端DNA聚合酶β样域就显示出戏剧性的保真度损失，最高可达100倍。我们进一步证明，通过显著降低错误核苷酸的掺入速率常数，非酶的亲线富含结构域增加了DNA聚合酶lambda的保真度。我们的研究揭示了一种新的机制，在这种机制中，DNA聚合酶的保真度不是由辅助蛋白或校对外切核酸酶结构域控制，而是由内部调节域控制。
DNA repair pathways are essential for maintaining genome stability. DNA polymerase beta plays a critical role in base-excision repair in vivo. DNA polymerase lambda, a recently identified X-family homolog of DNA polymerase beta, is hypothesized to be a second polymerase involved in base- excision repair. The full- length DNA polymerase lambda is comprised of three domains: a C-terminal DNA polymerase beta-like domain, an N-terminal BRCA1 C-terminal domain, and a previously uncharacterized proline- rich domain. Strikingly, pre-steady-state kinetic analyses reveal that, although human DNA polymerase lambda has almost identical fidelity to human DNA polymerase beta, the C-terminal DNA polymerase beta-like domain alone displays a dramatic, up to 100-fold loss in fidelity. We further demonstrate that the non-enzymatic pro-line-rich domain confers the increase in fidelity of DNA polymerase lambda by significantly lowering incorporation rate constants of incorrect nucleotides. Our studies illustrate a novel mechanism, in which the DNA polymerase fidelity is controlled not by an accessory protein or a proofreading exonuclease domain but by an internal regulatory domain.