Recombination of uracil-containing lambda bacteriophages.
Recombination of uracil-containing lambda bacteriophages.
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含尿嘧啶的 lambda 噬菌体的重组。
DOI：
10.1128/jb.145.1.306-320.1981
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发表时间：
1981
影响因子：
3.2
通讯作者：
Boehmer,S
中科院分区：
文献类型：
--
作者：
Hays,JB;Duncan,BK;Boehmer,S
通过在大肠杆菌突变体上生长，实现了λ噬菌体的脱氧核糖核酸（DNA）中尿嘧啶的可控掺入。用尿嘧啶DNA糖基化酶体外处理噬菌体DNA，通过碱性蔗糖沉降法估计，尿嘧啶取代胸腺嘧啶的频率范围为0.17 - 1.9%。野生型（Ung+）和糖基化酶缺陷（Ung-）细菌的接种效率之间的相应比值范围为0.70至0.05。如果假设平板接种效率对尿嘧啶含量的单次命中依赖性，则任何给定尿嘧啶残基致死的概率约为1%（约为嘧啶二聚体概率的五分之一）。尿嘧啶对重组的影响在λ串联重复序列（乙二胺四乙酸[EDTA]敏感）的实验中进行了研究，其通过一般重组转化为单拷贝重复序列（EDTA抗性）。对于（同种免疫溶原的）抑制感染，通过两阶段测定（DNA提取、原生质球转染和EDTA处理）测量重组。观察到的含尿嘧啶尿激酶的频率（2 - 4%）比对照值高5 - 10倍。然而，与紫外线照射的尿嘧啶的比较表明，尿嘧啶残基促进重组不到1/100的有效紫外线诱导的病变。在抑制感染过程中，recA中含尿嘧啶的细菌的降解可以忽略不计，而recB细菌的降解部分减少。在ung细胞中，切除修复非常低，表明切除修复是刺激的原因。有趣的是，尿嘧啶刺激的重组在xth细菌中升高了约两倍。
Controlled incorporation of uracil into the deoxyribonucleic acid (DNA) of lambda bacteriophages was achieved by growth on dut ung thy mutants of Escherichia coli. The frequency of substitution of uracil for thymine, estimated by alkaline sucrose sedimentation of phage DNA treated in vitro with uracil DNA glycosylase, ranged from 0.17 to 1.9%. The corresponding ratio between the plating efficiencies on wild-type (Ung+) and glycosylase-deficient (Ung-) bacteria ranged from 0.70 to 0.05. If a single-hit dependence of plating efficiency on uracil content is assumed, the probability that any given uracil residue is lethal is approximately 1% (about one-fifth the probability for a pyrimidine dimer). The effect of uracil on recombination was studied in experiments with lambda tandem duplication phages (ethylenediaminetetraacetic acid [EDTA] sensitive), which are converted to single-copy phages (EDTA resistant) by general recombination. For repressed infections (of homoimmune lysogens), recombination was measured by a two-stage assay (DNA extraction, transfection of spheroplasts, and EDTA treatment). The frequencies observed for uracil-containing phages (2 to 4%) were 5 to 10 times higher than control values. However, comparisons with ultraviolet irradiated phages indicated that uracil residues promoted recombination less than 1/100 as efficiently as ultraviolet-induced lesions. Recombination of uracil-containing phages during repressed infections was negligible in recA and partially reduced in recB bacteria. Recombination was very low in ung cells, suggesting that excision repair was responsible for the stimulation. Interestingly, uracil-stimulated recombination was elevated about twofold in xth bacteria.