Involvement of Escherichia coli Mismatch Repair in DNA Replication and Recombination

1984 ◽  
Vol 49 (0) ◽  
pp. 611-615 ◽  
Author(s):  
R. Wagner ◽  
C. Dohet ◽  
M. Jones ◽  
M.-P. Doutriaux ◽  
F. Hutchinson ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Dna Replication ◽  
Mismatch Repair

scholarly journals Spontaneous mutation in Escherichia coli containing the dnaE911 DNA polymerase antimutator allele.

Genetics ◽  
1994 ◽  
Vol 138 (2) ◽  
pp. 263-270 ◽  
Author(s):  
A R Oller ◽  
R M Schaaper
Keyword(s):  
Escherichia Coli ◽  
Dna Replication ◽  
Mismatch Repair ◽  
Dna Polymerase ◽  
Spontaneous Mutation ◽  
Gene Encoding ◽  
Replication Errors ◽  
Lac Operator ◽  
Laci Gene ◽  
Dna Replication Errors

Abstract We have previously isolated mutants of Escherichia coli that replicate their DNA with increased fidelity. These mutants have a mutation in the dnaE gene, encoding the alpha subunit of DNA polymerase III. They were isolated in a mismatch-repair-defective mutL background, in which mutations can be considered to represent uncorrected DNA replication errors. In the present study we analyze the effect of one of these alleles, dnaE911, on spontaneous mutagenesis in a mismatch-repair-proficient background. In this background, spontaneous mutations may be the sum of uncorrected replication errors and mutations resulting from other pathways. Hence, the effect of the dnaE allele may provide insights into the contribution of uncorrected DNA replication errors to spontaneous mutation. The data show that dnaE911 decreases the level of Rifr, lacI and galK mutations in this background by 1.5-2-fold. DNA sequencing of 748 forward mutants in the lacI gene reveals that this effect has a clear specificity. Transversions are decreased by approximately 3-fold, whereas transitions, frameshifts, deletions and duplications remain essentially unchanged. Among the transversions, A.T-->T.A are affected most strongly (approximately 6-fold). In addition to this effect on transversions within the lacI gene, one previously recognized A.T-->G.C base-pair substitution hotspot in the lac operator is also reduced (approximately 5-fold). The data are discussed in the light of the role of DNA replication errors in spontaneous mutation, as well as other possible explanations for the observed antimutator effects.

scholarly journals lon Incompatibility Associated with Mutations Causing SOS Induction: Null uvrD Alleles Induce an SOS Response in Escherichia coli

2000 ◽  
Vol 182 (11) ◽  
pp. 3151-3157 ◽  
Author(s):  
L. SaiSree ◽  
Manjula Reddy ◽  
J. Gowrishankar
Keyword(s):  
Escherichia Coli ◽  
Dna Replication ◽  
Mismatch Repair ◽  
Replication Fork ◽  
Excision Repair ◽  
Dna Helicase ◽  
Lon Protease ◽  
Sos Induction ◽  
Nucleotide Excision ◽  
Lagging Strand

ABSTRACT The uvrD gene in Escherichia coli encodes a 720-amino-acid 3′-5′ DNA helicase which, although nonessential for viability, is required for methyl-directed mismatch repair and nucleotide excision repair and furthermore is believed to participate in recombination and DNA replication. We have shown in this study that null mutations in uvrD are incompatible withlon, the incompatibility being a consequence of the chronic induction of SOS in uvrD strains and the resultant accumulation of the cell septation inhibitor SulA (which is a normal target for degradation by Lon protease). uvrD-lonincompatibility was suppressed by sulA,lexA3(Ind−), or recA (Def) mutations. Other mutations, such as priA, dam,polA, and dnaQ (mutD) mutations, which lead to persistent SOS induction, were also lonincompatible. SOS induction was not observed in uvrC andmutH (or mutS) mutants defective, respectively, in excision repair and mismatch repair. Nor wasuvrD-mediated SOS induction abolished by mutations in genes that affect mismatch repair (mutH), excision repair (uvrC), or recombination (recB andrecF). These data suggest that SOS induction inuvrD mutants is not a consequence of defects in these three pathways. We propose that the UvrD helicase participates in DNA replication to unwind secondary structures on the lagging strand immediately behind the progressing replication fork, and that it is the absence of this function which contributes to SOS induction inuvrD strains.

scholarly journals Termination complex in Escherichia coli inhibits SV40 DNA replication in vitro by impeding the action of T antigen helicase.

1992 ◽  
Vol 267 (8) ◽  
pp. 5361-5365
Author(s):  
M Hidaka ◽  
T Kobayashi ◽  
Y Ishimi ◽  
M Seki ◽  
T Enomoto ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Dna Replication ◽  
T Antigen ◽  
Sv40 Dna

scholarly journals Saturation of DNA Mismatch Repair and Error Catastrophe by a Base Analogue in Escherichia coli

Genetics ◽  
2002 ◽  
Vol 161 (4) ◽  
pp. 1363-1371
Author(s):  
Kazuo Negishi ◽  
David Loakes ◽  
Roel M Schaaper
Keyword(s):  
Escherichia Coli ◽  
Mismatch Repair ◽  
Dna Mismatch Repair ◽  
Repair System ◽  
Mutagenic Action ◽  
Wild Type ◽  
Dna Mismatch ◽  
Cell Counts ◽  
Error Catastrophe ◽  
Mismatch Repair System

Abstract Deoxyribosyl-dihydropyrimido[4,5-c][1,2]oxazin-7-one (dP) is a potent mutagenic deoxycytidine-derived base analogue capable of pairing with both A and G, thereby causing G · C → A · T and A · T → G · C transition mutations. We have found that the Escherichia coli DNA mismatch-repair system can protect cells against this mutagenic action. At a low dose, dP is much more mutagenic in mismatch-repair-defective mutH, mutL, and mutS strains than in a wild-type strain. At higher doses, the difference between the wild-type and the mutator strains becomes small, indicative of saturation of mismatch repair. Introduction of a plasmid containing the E. coli mutL+ gene significantly reduces dP-induced mutagenesis. Together, the results indicate that the mismatch-repair system can remove dP-induced replication errors, but that its capacity to remove dP-containing mismatches can readily be saturated. When cells are cultured at high dP concentration, mutant frequencies reach exceptionally high levels and viable cell counts are reduced. The observations are consistent with a hypothesis in which dP-induced cell killing and growth impairment result from excess mutations (error catastrophe), as previously observed spontaneously in proofreading-deficient mutD (dnaQ) strains.

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