Mutagenic DNA repair in Escherichia coli. V. Mutation frequency decline and error-free post-replication repair in an excision-proficient strain

1977 ◽  
Vol 42 ◽  
pp. 33-44 ◽  
Author(s):  
M.H.L. Green ◽  
B.A. Bridges ◽  
J.E. Eyfjörd ◽  
W.J. Muriel
Keyword(s):  
Escherichia Coli ◽  
Dna Repair ◽  
Mutation Frequency ◽  
Post Replication Repair ◽  
Mutagenic Dna Repair

scholarly journals Increased Mutation Frequency in Redox-Impaired Escherichia coli Due to RelA- and RpoS-Mediated Repression of DNA Repair

2010 ◽  
Vol 76 (16) ◽  
pp. 5463-5470 ◽  
Author(s):  
Amarjeet Singh ◽  
Anis Karimpour-Fard ◽  
Ryan T. Gill
Keyword(s):  
Escherichia Coli ◽  
Dna Repair ◽  
Mutation Frequency ◽  
Spontaneous Mutation ◽  
Regulatory Gene ◽  
Stringent Response ◽  
Anaerobic Growth ◽  
E Coli ◽  
Direct Measurements ◽  
Order Of Magnitude

ABSTRACT Balancing of reducing equivalents is a fundamental issue in bacterial metabolism and metabolic engineering. Mutations in the key metabolic genes ldhA and pflB of Escherichia coli are known to stall anaerobic growth and fermentation due to a buildup of intracellular NADH. We observed that the rate of spontaneous mutation in E. coli BW25113 (ΔldhA ΔpflB) was an order of magnitude higher than that in wild-type (WT) E. coli BW25113. We hypothesized that the increased mutation frequency was due to an increased NADH/NAD+ ratio in this strain. Using several redox-impaired strains of E. coli and different redox conditions, we confirmed a significant correlation (P < 0.01) between intracellular-NADH/NAD+ ratio and mutation frequency. To identify the genetic basis for this relationship, whole-genome transcriptional profiles were compared between BW25113 WT and BW25113 (ΔldhA ΔpflB). This analysis revealed that the genes involved in DNA repair were expressed at significantly lower levels in BW25113 (ΔldhA ΔpflB). Direct measurements of the extent of DNA repair in BW25113 (ΔldhA ΔpflB) subjected to UV exposure confirmed that DNA repair was inhibited. To identify a direct link between DNA repair and intracellular-redox ratio, the stringent-response-regulatory gene relA and the global-stress-response-regulatory gene rpoS were deleted. In both cases, the mutation frequencies were restored to BW25113 WT levels.

Mutagenic DNA repair in Escherichia coli

1975 ◽  
Vol 140 (3) ◽  
pp. 221-230 ◽  
Author(s):  
O. P. Doubleday ◽  
B. A. Bridges ◽  
M. H. L. Green
Keyword(s):  
Escherichia Coli ◽  
Dna Repair ◽  
Mutagenic Dna Repair
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