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酵母Polε在增殖细胞核抗原介导的自发损伤绕过过程中链相关偏向性的鉴定。

Identification of a strand-related bias in the PCNA-mediated bypass of spontaneous lesions by yeast Poleta.

作者信息

Abdulovic Amy L, Minesinger Brenda K, Jinks-Robertson Sue

机构信息

Graduate Program in Biochemistry, Cell and Developmental Biology Program, Emory University, Atlanta, GA 30322, United States.

出版信息

DNA Repair (Amst). 2007 Sep 1;6(9):1307-18. doi: 10.1016/j.dnarep.2007.02.026. Epub 2007 Apr 17.

Abstract

Translesion synthesis (TLS) DNA polymerases are specialized to bypass lesions that block replicative polymerases and prevent complete genome duplication. Current TLS models hypothesize that PCNA, the polymerase processivity clamp, is important for regulating the access and loading of the low fidelity TLS polymerases onto DNA in response to replication-blocking lesions. PCNA binds to the C-terminus of yeast Poleta, for example, and this interaction is required for cell survival after UV irradiation. Previously, we identified two spontaneous, Polzeta-dependent "complex" mutation hotspots using the lys2DeltaA746 frameshift reversion assay in repair-compromised cells. In the current study we observed an accumulation of Polzeta-dependent complex frameshifts at a third hotspot in Poleta-deficient cells. Interestingly, the sequence of this third hotspot is the reverse complement of the two hotspots previously identified, suggesting that the utilization of Polzeta and Poleta may be related to the position of the relevant lesion on either the leading- or lagging-strand template. Using the lys2DeltaA746 assay system, we investigated changes in the accumulation of complex events at hotspots when the direction of replication was reversed in repair-compromised cells with either wildtype Poleta, a deletion of Poleta, or a mutant of Poleta that cannot interact with PCNA. Our results suggest that there is a polymerase hierarchy between Poleta and Polzeta in the bypass of certain lesions and that the interaction of Poleta with PCNA is needed for some, but not all, spontaneous lesion bypass.

摘要

跨损伤合成(TLS)DNA聚合酶专门用于绕过阻碍复制性聚合酶并阻止基因组完全复制的损伤。当前的TLS模型假设,聚合酶持续性钳位蛋白PCNA对于响应复制阻断损伤调节低保真TLS聚合酶与DNA的结合及加载很重要。例如,PCNA与酵母Polζ的C末端结合,紫外线照射后细胞存活需要这种相互作用。此前,我们在修复缺陷细胞中使用lys2ΔA746移码回复试验鉴定了两个自发的、依赖Polζ的“复杂”突变热点。在本研究中,我们在Polζ缺陷细胞的第三个热点观察到依赖Polζ的复杂移码积累。有趣的是,第三个热点的序列是先前鉴定的两个热点的反向互补序列,这表明Polζ和Polζ的利用可能与前导链或滞后链模板上相关损伤的位置有关。使用lys2ΔA746试验系统,我们研究了在具有野生型Polζ、缺失Polζ或不能与PCNA相互作用的Polζ突变体的修复缺陷细胞中,复制方向反转时热点处复杂事件积累的变化。我们的结果表明,在绕过某些损伤时,Polζ和Polζ之间存在聚合酶层次结构,并且Polζ与PCNA的相互作用对于一些(但不是全部)自发损伤绕过是必需的。

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