The genetic toxicology of metal compounds: II. Enhancement of ultraviolet light-induced mutagenesis in escherichia coli WP2

1986 ◽  
Vol 8 (2) ◽  
pp. 263-271 ◽  
Author(s):  
T. G. Rossman ◽  
M. Molina
Keyword(s):  
Escherichia Coli ◽  
Ultraviolet Light ◽  
Genetic Toxicology ◽  
Metal Compounds ◽  
Induced Mutagenesis

scholarly journals L-Alanine Prototrophic Suppressors Emerge from L-Alanine Auxotroph through Stress-Induced Mutagenesis in Escherichia coli

2021 ◽  
Vol 9 (3) ◽  
pp. 472
Author(s):  
Harutaka Mishima ◽  
Hirokazu Watanabe ◽  
Kei Uchigasaki ◽  
So Shimoda ◽  
Shota Seki ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Pyruvate Dehydrogenase ◽  
Pyruvate Dehydrogenase Complex ◽  
Spontaneous Mutation ◽  
Point Mutations ◽  
Whole Genome Analysis ◽  
E Coli ◽  
Clone Pair ◽  
Induced Mutagenesis ◽  
Isogenic Mutants

In Escherichia coli, L-alanine is synthesized by three isozymes: YfbQ, YfdZ, and AvtA. When an E. coli L-alanine auxotrophic isogenic mutant lacking the three isozymes was grown on L-alanine-deficient minimal agar medium, L-alanine prototrophic mutants emerged considerably more frequently than by spontaneous mutation; the emergence frequency increased over time, and, in an L-alanine-supplemented minimal medium, correlated inversely with L-alanine concentration, indicating that the mutants were derived through stress-induced mutagenesis. Whole-genome analysis of 40 independent L-alanine prototrophic mutants identified 16 and 18 clones harboring point mutation(s) in pyruvate dehydrogenase complex and phosphotransacetylase-acetate kinase pathway, which respectively produce acetyl coenzyme A and acetate from pyruvate. When two point mutations identified in L-alanine prototrophic mutants, in pta (D656A) and aceE (G147D), were individually introduced into the original L-alanine auxotroph, the isogenic mutants exhibited almost identical growth recovery as the respective cognate mutants. Each original- and isogenic-clone pair carrying the pta or aceE mutation showed extremely low phosphotransacetylase or pyruvate dehydrogenase activity, respectively. Lastly, extracellularly-added pyruvate, which dose-dependently supported L-alanine auxotroph growth, relieved the L-alanine starvation stress, preventing the emergence of L-alanine prototrophic mutants. Thus, L-alanine starvation-provoked stress-induced mutagenesis in the L-alanine auxotroph could lead to intracellular pyruvate increase, which eventually induces L-alanine prototrophy.

Methyl cinnamate derivatives enhance UV-induced mutagenesis due to the inhibition of DNA excision repair in Escherichia coli B/r

1985 ◽  
Vol 146 (1) ◽  
pp. 15-22 ◽  
Author(s):  
Kayoko Shimoi ◽  
Yoshiyuki Nakamura ◽  
Tadataka Noro ◽  
Isao Tomita ◽  
Seigo Fukushima ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Excision Repair ◽  
Methyl Cinnamate ◽  
Dna Excision Repair ◽  
Induced Mutagenesis ◽  
Escherichia Coli B
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