Pathways of Resistance to Thymineless Death in Escherichia coli and the Function of UvrD
Pathways of Resistance to Thymineless Death in Escherichia coli and the Function of UvrD
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DOI：
10.1534/genetics.111.130161
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发表时间：
2011-09-01
期刊：
影响因子：
3.3
通讯作者：
Rosenberg, Susan M.
中科院分区：
文献类型：
--
作者：
Fonville, Natalie C.;Vaksman, Zalman;Rosenberg, Susan M.
无胸腺素性死亡(TLD)是指缺乏胸腺嘧啶的细菌、酵母和人类细胞迅速丧失活力。TLD是常见抗癌药物和一些抗生素的作用方式。大肠杆菌中的TLD伴随着复制受阻和染色体DNA丢失，最近的工作发现重组蛋白RecA的活性和SOS DNA损伤反应是TLD的原因。在这里，我们研究了缺乏UvrD解旋酶、RecBCD外切酶和RuvABC Holliday连接解析酶的突变体对胸腺嘧啶剥夺超敏反应的基础。UvrD解旋酶反对RecA作用并参与一些DNA修复机制，RecBCD外核酸酶降解双链线性DNA并与RecA一起参与双链断裂修复和SOS诱导。我们报告说，Delta UvrD细胞中的高TLD部分依赖于RecA，不能归因于错配修复或核苷酸切除修复中中间体的积累。这些数据表明，UvrD在对抗RecA中的已知作用和UvrD的另一个未知功能都促进了TLD抵抗。Delta ruvABC细胞的高TLD需要RecA，而不需要RecQ或RecJ。RecB细胞的高TLD既不需要RecA也不需要RecQ，这意味着重组和SOS诱导都不会导致RecB细胞的高TLD，并且RecQ并不像以前提出的那样是TLD过程中双链末端(DSE)的唯一来源；提出了一些模型。这些结果定义了细胞抵抗TLD的途径，并提出了在化疗期间对抗TLD耐药性的策略。
Thymineless death (TLD) is the rapid loss of viability in bacterial, yeast, and human cells starved of thymine. TLD is the mode of action of common anticancer drugs and some antibiotics. TLD in Escherichia coli is accompanied by blocked replication and chromosomal DNA loss and recent work identified activities of recombination protein RecA and the SOS DNA-damage response as causes of TLD. Here, we examine the basis of hypersensitivity to thymine deprivation (hyper-TLD) in mutants that lack the UvrD helicase, which opposes RecA action and participates in some DNA repair mechanisms, RecBCD exonuclease, which degrades double-stranded linear DNA and works with RecA in double-strand-break repair and SOS induction, and RuvABC Holliday-junction resolvase. We report that hyper-TLD in Delta uvrD cells is partly RecA dependent and cannot be attributed to accumulation of intermediates in mismatch repair or nucleotide-excision repair. These data imply that both its known role in opposing RecA and an additional as-yet-unknown function of UvrD promote TLD resistance. The hyper-TLD of Delta ruvABC cells requires RecA but not RecQ or RecJ. The hyper-TLD of recB cells requires neither RecA nor RecQ, implying that neither recombination nor SOS induction causes hyper-TLD in recB cells, and RecQ is not the sole source of double-strand ends (DSEs) during TLD, as previously proposed; models are suggested. These results define pathways by which cells resist TLD and suggest strategies for combating TLD resistance during chemotherapies.