Disease relevance of lacI

• A genetic system developed by Miller and colleagues allows the mutation frequencies of a large number of different base pairs in the lacI gene of Escherichia coli to be compared [1].
• The mutant lacI gene and the wild-type (wt) gene, both in standard animal cell expression vectors, driven by the promoter of the Rous sarcoma virus long terminal repeat, were stably transfected into three rodent cell lines [2].
• Specificity of spontaneous mutation in the lacI gene cloned into bacteriophage M13 [3].

High impact information on lacI

• A recently completed study of mutagenesis with neocarzinostatin (NCS) in the lacI gene has prompted us to re-examine some previous studies, of mutagenesis in this gene [1].
• As a result, 5-methylcytosine residues are hotspots for spontaneous transitions, as demonstrated in the lacI gene of Escherichia coli [4].
• To facilitate the sequencing, the lacI gene was cloned in a small plasmid [5].
• The promoter for a weakly expressed constitutive gene, the lactose repressor gene (lacI), has been sequenced, along with an 'up' promoter mutation Iq [5].
• By taking advantage of mutants deficient in cytosine methylation, we show here that at the three sites in the lacI gene of Escherichia coli having this sequence, the specific increase in the formation of the (6-4) photoproducts is accompanied by a concomitant increase in mutation [6].

Chemical compound and disease context of lacI

• N-methyl-N'-nitro-N-nitrosoguanidine (MNNG)-induced forward mutations within the first 540 base-pairs of the lacI gene of Escherichia coli were cloned and sequenced [7].
• N-acetoxy-N-acetyl-2-aminofluorene-induced mutagenesis in the lacI gene of Escherichia coli [8].
• Mutational specificities of environmental carcinogens in the lacI gene of Escherichia coli. VI: Analysis of methylene chloride-induced mutational distribution in Uvr+ and UvrB- strains [9].
• The role of pyrimidine dimers as premutagenic lesions: a study of targeted vs. untargeted mutagenesis in the lacI gene of Escherichia coli [10].
• Distribution and specificity of mutations induced by neocarzinostatin in the lacI gene of Escherichia coli [11].

Biological context of lacI

• The DNA sequence changes were determined for 61 lacI mutations induced by exposure of one of the cell lines to N-nitroso-N-methylurea [12].
• A total of 33 of 34 lacI nonsense mutations and 26 of 27 missense mutations involve G X C to A X T transitions [12].
• Defect in excision repair alters the mutational specificity of PUVA treatment in the lacI gene of Escherichia coli [13].
• We report the sequence changes in the Escherichia coli lacI gene in 133 mutants detected after passage of an ultraviolet-irradiated shuttle vector human 293 cells [14].
• A novel forward mutational system, based on the acquisition of an Iq-d dominant phenotype from an initial Iq- recessive state, was used to identify second-site frameshift mutation [+/- 1(+/- 3n) events] within the N-terminal region of the lacI gene of Escherichia coli [15].

Anatomical context of lacI

• Mutant frequency and molecular analysis of in vivo lacI mutations in the bone marrow of Big Blue rats treated with 7, 12-dimethylbenz[a]anthracene [16].
• Recently, we evaluated lacI mutations in lymphocytes and mammary tissue of Big Blue (BB) rats exposed to 7, 12-dimethylbenz[a]anthracene (DMBA) [16].
• The distribution of R7000-induced mutations in the lacI gene recovered from small intestine of transgenic mice was very similar to that which had been found in E. coli [17].

Associations of lacI with chemical compounds

• Since the lacI gene is not A + T-rich, the contribution of IS1 insertion to spontaneous mutation in general might be underestimated [18].
• This treatment reduced the frequency of induced lacI mutations by 70 to 80%, indicating that cyclobutane dimers cause most mutations in this system [19].
• Mutagenic properties of a nitrofuran, 7-methoxy-2-nitronaphtho[2, 1-b]furan (R7000), in lacI transgenic mice [17].

Other interactions of lacI

• Thermal resistance to photoreactivation of ultraviolet light induced mutations in the lacI gene of E. coli ung [20].

References