Hypermutability of damaged single-strand DNA formed at double-strand breaks and uncapped telomeres in yeast Saccharomyces cerevisiae.
Hypermutability of damaged single-strand DNA formed at double-strand breaks and uncapped telomeres in yeast Saccharomyces cerevisiae.
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酿酒酵母中双链断裂和未加帽端粒处形成的受损单链 DNA 的超突变性。
DOI：
10.1371/journal.pgen.1000264
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发表时间：
2008-11
期刊：
影响因子：
4.5
通讯作者：
Gordenin DA
中科院分区：
文献类型：
--
作者：
Yang Y;Sterling J;Storici F;Resnick MA;Gordenin DA
主要的DNA修复途径对双链DNA的损伤起作用，因为它们在损伤去除后使用完整的链作为模板。因此，染色体DNA瞬间单链延伸中的损伤预计将特别威胁到基因组的稳定性。为了验证这一假设，我们在萌芽酵母中设计了系统，可以在双链断裂或未封顶的端粒旁边产生数千个碱基的持久单链DNA。该系统允许在施加DNA损伤后控制恢复到双链状态。我们发现紫外线和甲烷磺酸甲酯诱导的损伤在长单链区域是可以耐受的，并且是高度诱变的。这种高度的变异性需要增殖细胞核抗原的单一素化，这在很大程度上归因于容易出错的DNA聚合酶ζ的跨损伤合成。为了支持单链DNA的多个损伤是高度突变性的来源，对紫外线诱导的突变体的分析显示，强烈的链特异性偏向和出人意料的高频率等位基因具有广泛分布在几千个碱基上的多个突变。与长单链DNA瞬间延伸中的损伤相关的超突变和多个突变可能是致癌的来源，并在适应性进化中提供选择性优势。各种错误避免机制确保了整个基因组的低突变率。DNA复制或修复中的遗传缺陷会导致全基因组范围内突变频率的增加，从而可能导致癌症易感性和遗传性疾病。瞬时的局部高度突变性在生物学后果上与全基因组突变体有很大的不同。由于全基因组的高度变异性会由于功能失调的等位基因的积累而导致适合度降低，突变者面临着负面的选择压力。相比之下，在有限的基因组区域内，针对暂时性高度变异性的选择会更少，这表明在适应性进化和癌症发生中具有特殊的作用。人们对瞬变的机制知之甚少。单链DNA的长片段已经被证明是局部瞬时高度变异性的来源，但还没有被证实。利用我们开发的复杂的酵母遗传系统，我们发现染色体单链DNA在双链断裂时的瞬时伸展，端粒可以耐受多种损伤，并且非常容易发生损伤诱导的突变，包括一类非常不寻常的广泛分布的多个突变。这种高度易变性依赖于容易出错的跨损伤DNA合成。我们的工作证明了一种简单的体内机制，即扩展到几千个碱基的局部瞬时高变异性，可以导致广泛分布的多个突变，而不会在基因组的其余部分产生严重的突变负载。
The major DNA repair pathways operate on damage in double-strand DNA because they use the intact strand as a template after damage removal. Therefore, lesions in transient single-strand stretches of chromosomal DNA are expected to be especially threatening to genome stability. To test this hypothesis, we designed systems in budding yeast that could generate many kilobases of persistent single-strand DNA next to double-strand breaks or uncapped telomeres. The systems allowed controlled restoration to the double-strand state after applying DNA damage. We found that lesions induced by UV-light and methyl methanesulfonate can be tolerated in long single-strand regions and are hypermutagenic. The hypermutability required PCNA monoubiquitination and was largely attributable to translesion synthesis by the error-prone DNA polymerase ζ. In support of multiple lesions in single-strand DNA being a source of hypermutability, analysis of the UV-induced mutants revealed strong strand-specific bias and unexpectedly high frequency of alleles with widely separated multiple mutations scattered over several kilobases. Hypermutability and multiple mutations associated with lesions in transient stretches of long single-strand DNA may be a source of carcinogenesis and provide selective advantage in adaptive evolution. A variety of error avoidance mechanisms assure low mutation rates across the genome. Genetic defects in DNA replication or repair can lead to genome-wide increase in mutation frequency that may result in cancer predisposition and genetic disease. Transient localized hypermutability drastically differs in its biological consequences from genome-wide mutators. Since genome-wide hypermutability can cause reduced fitness due to accumulation of dysfunctional alleles, mutators are under negative selection pressure. By contrast, there would be less selection against temporary hypermutability within limited genomic regions, suggesting a special role in adaptive evolution and carcinogenesis. Mechanisms of transient hypermutability are poorly understood. Long stretches of single-strand DNA have been implicated but not demonstrated as a source of localized transient hypermutability. Using sophisticated yeast genetic systems that we developed, we found that transient stretches of chromosomal single-strand DNA at double-strand breaks and that telomeres can tolerate multiple lesions and are highly prone to damage-induced mutations, including a very unusual class of widely spaced multiple mutations. The hypermutability relied on error prone translesion DNA synthesis. Our work demonstrates a simple in vivo mechanism for localized transient hypermutability extending over several kilobases that can result in widely spaced multiple mutations without severe mutation load in the rest of the genome.
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DOI：
10.1083/jcb.200510130
发表时间：
2006-04-24
期刊：
The Journal of cell biology
影响因子：
--
作者：
Bekker-Jensen S;Lukas C;Kitagawa R;Melander F;Kastan MB;Bartek J;Lukas J
通讯作者：
Lukas J
影响因子：
14.9
作者：
Kozmin, SG;Pavlov, YI;Sage, E
通讯作者：
Sage, E
DOI：
10.1073/pnas.0503009102
发表时间：
2005-09-06
影响因子：
11.1
作者：
Drake, JW;Bebenek, A;Peddada, S
通讯作者：
Peddada, S
影响因子：
11.4
作者：
Northam, Matthew R.;Garg, Parie;Shcherbakova, Polina V.
通讯作者：
Shcherbakova, Polina V.
影响因子：
64.8
作者：
BJURSELL, G;GUSSANDER, E;LINDAHL, T
通讯作者：
LINDAHL, T