A set of lacZ mutations in Escherichia coli that allow rapid detection of specific frameshift mutations.
A set of lacZ mutations in Escherichia coli that allow rapid detection of specific frameshift mutations.
复制标题
大肠杆菌中的一组 lacZ 突变，可以快速检测特定的移码突变。
作者：
C. Cupples;Mila Cabrera;Chris Cruz;Jeffrey H Miller
我们已经使用定点突变来改变LacZ中的碱基，该碱基位于编码β-半乳糖苷酶活性部位的基本残基的区域附近。改变的序列产生六个或七个相同碱基对的序列，这产生了移码，导致了Lac-表型。在每个菌株中，只有通过这些序列上的特定移码才能恢复到Lac+。A‘s(或相反链上的T’s)和G‘s(或C’s)的单调序列已经被构造出来，还有一个交替的-C-G-序列。这些特定的移码指示剂菌株补充了前面描述的一组六个菌株，这些菌株检测到了每个碱基替换。我们已经检测了各种诱变剂和突变剂的能力，以使其回复到Lac+。令人惊讶的是，在许多这样的运行中，甲磺酸乙酯、N-甲基-N‘-硝基-N-亚硝基和2-氨基嘌呤都能很好地刺激移码，这些突变剂并不广为人知地诱导移码。对甲烷磺酸乙酯、N-甲基-N‘-硝基-N-亚硝基和2-氨基嘌呤移码特异性与Muth菌株的比较表明，这些诱变剂部分或完全饱和或失活甲基化导向的错配修复系统，并允许复制错误导致移码逃避修复。这导致了一种间接突变的形式，可以在某些位置检测到这种突变。
We have used site-directed mutagenesis to alter bases in lacZ near the region encoding essential residues in the active site of beta-galactosidase. The altered sequences generate runs of six or seven identical base pairs which create a frameshift, resulting in a Lac- phenotype. Reversion to Lac+ in each strain can occur only by a specific frameshift at these sequences. Monotonous runs of A's (or of T's on the opposite strand) and G's (or C's) have been constructed, as has an alternating -C-G- sequence. These specific frameshift indicator strains complement a set of six previously described strains which detect each of the base substitutions. We have examined a variety of mutagens and mutators for their ability to cause reversion to Lac+. Surprisingly, frameshifts are well stimulated at many of these runs by ethyl methanesulfonate, N-methyl-N'-nitro-N-nitrosoguanidine and 2-amino-purine, mutagens not widely known to induce frameshifts. A comparison of ethyl methanesulfonate, N-methyl-N'-nitro-N-nitrosoguanidine and 2-aminopurine frameshift specificity with that found with a mutH strain suggests that these mutagens partially or fully saturate or inactivate the methylation-directed mismatch repair system and allow replication errors leading to frameshifts to escape repair. This results in a form of indirect mutagenesis, which can be detected at certain sites.
根据诱变剂引起六种可能的转变和颠换的特异性进行分类：使用沙门氏菌致突变性测定的简单分析。
DOI：
10.1002/em.2860080103
发表时间：
1986
期刊：
Environmental mutagenesis
影响因子：
--
作者：
Levin,DE;Ames,BN
通讯作者：
Ames,BN