Cell death in Escherichia coli dnaE(Ts) mutants incubated at a nonpermissive temperature is prevented by mutation in the cydA gene.
Cell death in Escherichia coli dnaE(Ts) mutants incubated at a nonpermissive temperature is prevented by mutation in the cydA gene.
复制标题
在不允许的温度下孵育的大肠杆菌 dnaE(Ts) 突变体中的细胞死亡可以通过 cydA 基因的突变来防止。
DOI：
10.1128/jb.186.7.2147-2155.2004
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发表时间：
2004
影响因子：
3.2
通讯作者：
Song,Richard
中科院分区：
文献类型：
--
作者：
Strauss,Bernard;Kelly,Kemba;Dincman,Toros;Ekiert,Damian;Biesieda,Theresa;Song,Richard
突变株dna E(Ts)dna E(Ts)dna E74和dna E486在Luria-Bertani培养液中40℃孵育4h后死亡。细胞死亡发生在延长之前，由氯霉素、四环素或利福平抑制，并依赖于细胞密度。当细胞在条件培养液中以高密度或低密度孵育时，细胞在40℃下存活，但当培养液中添加葡萄糖和氨基酸时，细胞死亡。删除recAorsulA不起作用。我们分离出在40℃下长时间存活但没有形成集落的抑制子。抑制子对羟基脲诱导的杀伤具有保护作用。序列分析和互补分析表明，抑制是由于yecdA基因的突变所致。在40℃下，dna突变体的DNA含量在4h内增加了约8倍，抑制株的DNA含量也增加了约8倍。在凝胶上测得，AdnaE74菌株中pBR322的数量增加了约4倍，即使亲本细胞的活力下降了2logS，但电泳图谱似乎是正常的。转化活性也有所增加。4‘，6’-联胺-2-苯基吲哚染色表明，在40℃时形成的DNA细丝中有类核物质分布，表明新形成的DNA发生了分离。我们的结论是，合成的DNA具有生理活性，特别是因为受抑制菌株的活细胞数量在孵育的最初几个小时内增加了。这些观察结果支持这一观点。当DNA合成速率下降到相对于RNA和蛋白质合成水平的临界水平以下时，DNA合成速率就会分裂，并抑制分裂。
Cells of theEscherichia coli dnaE(Ts)dnaE74anddnaE486mutants die after 4 h of incubation at 40°C in Luria-Bertani medium. Cell death is preceded by elongation, is inhibited by chloramphenicol, tetracycline, or rifampin, and is dependent on cell density. Cells survive at 40°C when they are incubated at a high population density or at a low density in conditioned medium, but they die when the medium is supplemented with glucose and amino acids. Deletion ofrecAorsulAhas no effect. We isolated suppressors which survived for long periods at 40°C but did not form colonies. The suppressors protected against hydroxyurea-induced killing. Sequence and complementation analysis indicated that suppression was due to mutation in thecydAgene. The DNA content ofdnaEmutants increased about eightfold in 4 h at 40°C, as did the DNA content of the suppressed strains. The amount of plasmid pBR322 in adnaE74strain increased about fourfold, as measured on gels, and the electrophoretic pattern appeared to be normal even though the viability of the parent cells decreased 2 logs. Transformation activity also increased. 4′,6′-Diamidino-2-phenylindole staining demonstrated that there were nucleoids distributed throughout thednaEfilaments formed at 40°C, indicating that there was segregation of the newly formed DNA. We concluded that the DNA synthesized was physiologically competent, particularly since the number of viable cells of the suppressed strain increased during the first few hours of incubation. These observations support the view thatE. colisenses the rate of DNA synthesis and inhibits septation when the rate of DNA synthesis falls below a critical level relative to the level of RNA and protein synthesis.