Synthetic lethality with the dut defect in Escherichia coli reveals layers of DNA damage of increasing complexity due to uracil incorporation.
Synthetic lethality with the dut defect in Escherichia coli reveals layers of DNA damage of increasing complexity due to uracil incorporation.
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大肠杆菌中 dut 缺陷的合成致死率揭示了由于尿嘧啶掺入而导致的 DNA 损伤层的复杂性不断增加。
DOI：
10.1128/jb.00711-08
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发表时间：
2008
影响因子：
3.2
通讯作者：
Kuzminov,Andrei
中科院分区：
文献类型：
--
作者：
Ting,Helen;Kouzminova,ElenaA;Kuzminov,Andrei
合成致死性是两个完全可行的单突变体的双突变体组合的失活，通常被解释为在一个必要的代谢步骤的冗余。大肠杆菌中的dut-1缺陷使dUTR失活，导致DNA中尿嘧啶掺入增加和已知的合成致死[SL（dut）突变]。根据冗余逻辑，这些SL（dut）突变中的大多数应该影响核苷酸代谢。在对SL（dut）突变体进行系统搜索后，我们确实发现了DNA前体代谢中的一个单一缺陷，使胸苷激酶（tdk）失活，这证实了合成致死性的冗余解释。然而，我们发现大部分突变在DNA修复中与尿嘧啶基因相互作用，揭示了尿嘧啶-DNA掺入通过染色体代谢发送的日益复杂的损伤层。因此，我们分离了涉及以下功能的突变体：（i）尿嘧啶-DNA切除（ung，polA和xthA）;（ii）双链DNA断裂修复（recA，recBC和ruvABC）;和（iii）染色体二聚体解析（xerC，xerD和ftsK）。这些突变体在各种DNA修复过程中不能与dUTR冗余，而是揭示了连接不相关代谢途径的“缺陷-损伤-修复”循环。此外，两个SL（dut）插入（phoUanddegP）确定的功能，可以采取行动，以支持Dut-1突变酶的活性减弱，这表明这种合成致死性的“补偿”解释。我们的结论是，基因的相互作用可以解释为冗余，缺陷-损伤-修复周期，或作为补偿。
Synthetic lethality is inviability of a double-mutant combination of two fully viable single mutants, commonly interpreted as redundancy at an essential metabolic step. Thedut-1defect inEscherichia coliinactivates dUTPase, causing increased uracil incorporation in DNA and known synthetic lethalities [SL(dut) mutations]. According to the redundancy logic, most of these SL(dut) mutations should affect nucleotide metabolism. After a systematic search for SL(dut) mutants, we did identify a single defect in the DNA precursor metabolism, inactivating thymidine kinase (tdk), that confirmed the redundancy explanation of synthetic lethality. However, we found that the bulk of mutations interacting genetically withdutare in DNA repair, revealing layers of damage of increasing complexity that uracil-DNA incorporation sends through the chromosomal metabolism. Thus, we isolated mutants in functions involved in (i) uracil-DNA excision (ung,polA, andxthA); (ii) double-strand DNA break repair (recA,recBC, andruvABC); and (iii) chromosomal-dimer resolution (xerC,xerD, andftsK). These mutants in various DNA repair transactions cannot be redundant with dUTPase and instead reveal “defect-damage-repair” cycles linking unrelated metabolic pathways. In addition, two SL(dut) inserts (phoUanddegP) identify functions that could act to support the weakened activity of the Dut-1 mutant enzyme, suggesting the “compensation” explanation for this synthetic lethality. We conclude that genetic interactions withdutcan be explained by redundancy, by defect-damage-repair cycles, or as compensation.