SYNTHESIS AND METABOLISM OF URACIL-CONTAINING DEOXYRIBONUCLEIC-ACID IN ESCHERICHIA-COLI
SYNTHESIS AND METABOLISM OF URACIL-CONTAINING DEOXYRIBONUCLEIC-ACID IN ESCHERICHIA-COLI
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DOI：
10.1128/jb.145.2.687-695.1981
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发表时间：
1981-01-01
影响因子：
3.2
通讯作者：
NEUHARD, J
中科院分区：
文献类型：
--
作者：
WARNER, HR;DUNCAN, BK;NEUHARD, J
在缺乏尿嘧啶-DNA糖基化酶（ung）和脱氧尿嘧啶5′-三磷酸核苷酸水解酶（dut）活性的大肠杆菌突变体DNA中发现了大量尿嘧啶；在野生型细胞的DNA中发现少量尿嘧啶，并且细胞仅缺乏这两种活性中的一种。dut突变体DNA中尿嘧啶的含量与培养物的生长温度直接相关，这显然是由于dut突变体合成的脱氧尿嘧啶5′-三磷酸核苷酸水解酶对温度敏感。所使用的dut突变体未能呈指数增长，在25度以上的温度下变成丝状。C并表现出超增表型；ung突变抑制了所有这些影响。尽管在所有温度下，突变体都呈指数增长，但其生长速度始终低于野生型的生长速度。由于池大小测量表明，dut突变体中三磷酸脱氧尿嘧啶和三磷酸脱氧胸腺嘧啶池明显增加，因此dut细胞生长速度的降低显然是由于DNA中尿嘧啶的实际存在，而不是由于DNA合成所需的三磷酸脱氧尿嘧啶和三磷酸脱氧胸腺嘧啶的缺乏。当受体细胞处于ung+状态时，尿嘧啶在大肠杆菌供体DNA中的存在显著降低了重组频率，表明DNA修复在进入DNA复制之前就开始了。
Significant amounts of uracil were found in the DNA of E. coli mutants deficient in uracil-DNA glycosylase (ung) and deoxyuridine 5''-triphosphate nucleotidohydrolase (dut) activities; little uracil was found in the DNA of wild-type cells and cells deficient in only 1 of these 2 activities. The amounts of uracil found in the DNA of dut ung mutants were directly related to the growth temperature of the cultures, apparently because the deoxyuridine 5''-triphosphate nucleotidohydrolase synthesized by dut mutants was temperature sensitive. The dut mutant used failed to grow exponentially, became filamentous at temperatures above 25.degree. C and exhibited a hyperec phenotype; the ung mutation suppressed all of these effects. Although the dut ung mutants grew exponentially at all temperatures, their growth rates were always slower than the growth rate of the wild type. Since pool size measurements indicated that deoxyuridine triphosphate and deoxythymidine triphosphate pools were markedly elevated in dut mutants, the reduced growth rate of dut ung cells apparently was due to the actual presence of uracil in the DNA, rather than to a deficiency of deoxyuridine triphosphate and deoxyribosylthymine triphosphate for DNA synthesis. The presence of uracil in E. coli donor DNA markedly reduced the recombination frequency when the recipient cells were ung+, indicating that DNA repair commenced before the entering DNA could be replicated.