Ribonucleoside and deoxyribonucleoside triphosphate pools during 2-aminopurine mutagenesis in T4 mutator-, wild type-, and antimutator-infected Escherichia coli.

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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Escherichia coli MutM Suppresses Illegitimate Recombination Induced by Oxidative Stress

Genetics ◽

10.1093/genetics/151.2.439 ◽

1999 ◽

Vol 151 (2) ◽

pp. 439-446 ◽

Cited By ~ 2

Author(s):

Masaaki Onda ◽

Katsuhiro Hanada ◽

Hirokazu Kawachi ◽

Hideo Ikeda

Keyword(s):

Oxidative Stress ◽

Escherichia Coli ◽

Hydrogen Peroxide ◽

Dna Damage ◽

Double Strand Breaks ◽

Illegitimate Recombination ◽

Recombination Analysis ◽

Wild Type ◽

Strand Breaks ◽

In The Wild

Abstract DNA damage by oxidative stress is one of the causes of mutagenesis. However, whether or not DNA damage induces illegitimate recombination has not been determined. To study the effect of oxidative stress on illegitimate recombination, we examined the frequency of λbio transducing phage in the presence of hydrogen peroxide and found that this reagent enhances illegitimate recombination. To clarify the types of illegitimate recombination, we examined the effect of mutations in mutM and related genes on the process. The frequency of λbio transducing phage was 5- to 12-fold higher in the mutM mutant than in the wild type, while the frequency in the mutY and mutT mutants was comparable to that of the wild type. Because 7,8-dihydro-8-oxoguanine (8-oxoG) and formamido pyrimidine (Fapy) lesions can be removed from DNA by MutM protein, these lesions are thought to induce illegitimate recombination. Analysis of recombination junctions showed that the recombination at Hotspot I accounts for 22 or 4% of total λbio transducing phages in the wild type or in the mutM mutant, respectively. The preferential increase of recombination at nonhotspot sites with hydrogen peroxide in the mutM mutant was discussed on the basis of a new model, in which 8-oxoG and/or Fapy residues may introduce double-strand breaks into DNA.

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Phage genetic sites involved in lambda growth inhibition by the Escherichia coli rap mutant.

Genetics ◽

10.1093/genetics/121.3.401 ◽

1989 ◽

Vol 121 (3) ◽

pp. 401-409

Author(s):

P Guzmán ◽

G Guarneros

Keyword(s):

Escherichia Coli ◽

Growth Inhibition ◽

Phage Genome ◽

Bacteriophage Lambda ◽

Phage Lambda ◽

Wild Type ◽

Attp Site

Abstract The rap mutation of Escherichia coli prevents the growth of bacteriophage lambda. We have isolated phage mutants that compensate for the host deficiency. The mutations, named bar, were genetically located to three different loci of the lambda genome: barI in the attP site, barII in the cIII ea10 region, and barIII within or very near the imm434 region. The level of lambda leftward transcription correlates with rap exclusion. Phage lambda mutants partially defective in the pL promoter or in pL-transcript antitermination showed a Bar- phenotype. Conversely, mutants constitutive for transcription from the pI or pL promoters were excluded more stringently by rap bacteria. We conclude that rap exclusion depends on the magnitude of transcription through the wild type bar loci in the phage genome.

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Modelling inactivation of wild‐type and clinical Escherichia coli O26 strains using UV‐C and thermal treatment and subsequent persistence in simulated gastric fluid

Journal of Applied Microbiology ◽

10.1111/jam.14397 ◽

2019 ◽

Vol 127 (5) ◽

pp. 1564-1575 ◽

Cited By ~ 5

Author(s):

V.S. Castro ◽

D.K.A. Rosario ◽

Y.S. Mutz ◽

A.C.C. Paletta ◽

E.E.S. Figueiredo ◽

...

Keyword(s):

Escherichia Coli ◽

Thermal Treatment ◽

Gastric Fluid ◽

Simulated Gastric Fluid ◽

Wild Type ◽

Uv C

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Differential Suppression of priA2::kan Phenotypes in Escherichia coli K-12 by Mutations in priA, lexA, and dnaC

Genetics ◽

10.1093/genetics/143.1.5 ◽

1996 ◽

Vol 143 (1) ◽

pp. 5-13 ◽

Cited By ~ 21

Author(s):

Steven J Sandler ◽

Hardeep S Samra ◽

Alvin J Clark

Keyword(s):

Escherichia Coli ◽

Dna Replication ◽

Mutant Allele ◽

Wild Type ◽

Suppressor Mutations ◽

Dnab Helicase ◽

K 12 ◽

Extragenic Suppressors ◽

Assembly Activity

Abstract First identified as an essential component of the ϕX174 in vitro DNA replication system, PriA has ATPase, helicase, translocase, and primosome-assembly activities. priA1::kan strains of Escherichia coli are sensitive to UV irradiation, deficient in homologous recombination following transduction, and filamentous. priA2::kan strains have eightfold higher levels of uninduced SOS expression than wild type. We show that (1) priA1::kan strains have eightfold higher levels of uninduced SOS expression, (2) priA2::kan strains are UVS and Rec−, (3) lexA3 suppresses the high basal levels of SOS expression of a priA2::kan strain, and (4) plasmid-encoded priA300 (K230R), a mutant allele retaining only the primosome-assembly activity of priA+, restores both UVR and Rec+ phenotypes to a priA2::kan strain. Finally, we have isolated 17 independent UVR Rec+ revertants of priA2::kan strains that carry extragenic suppressors. All 17 map in the C-terminal half of the dnaC gene. DnaC loads the DnaB helicase onto DNA as a prelude for primosome assembly and DNA replication. We conclude that priA's primosome-assembly activity is essential for DNA repair and recombination and that the dnaC suppressor mutations allow these processes to occur in the absence of priA.

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Gene replacement with linear DNA in electroporated wild-type Escherichia coli

Nucleic Acids Research ◽

10.1093/nar/27.5.1296 ◽

1999 ◽

Vol 27 (5) ◽

pp. 1296-1299 ◽

Cited By ~ 26

Author(s):

M El Karoui

Keyword(s):

Escherichia Coli ◽

Gene Replacement ◽

Wild Type ◽

Linear Dna

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Expression of wild-type and mutated rabbit osteopontin in Escherichia coli, and their effects on adhesion and migration of P388D1 cells

Biochemical Journal ◽

10.1042/bj3070257 ◽

1995 ◽

Vol 307 (1) ◽

pp. 257-265 ◽

Cited By ~ 32

Author(s):

K Nasu ◽

T Ishida ◽

M Setoguchi ◽

Y Higuchi ◽

S Akizuki ◽

...

Keyword(s):

Escherichia Coli ◽

Fluid Phase ◽

Intradermal Injection ◽

Polymorphonuclear Leucocyte ◽

Alpha Subunit ◽

Wild Type ◽

Alpha Subunits ◽

Leucocyte Migration ◽

And Migration ◽

Chemotactic Effect

Recombinant wild-type rabbit osteopontin (rOP) and the protein with an aspartate-to-glutamate transposition induced by a point mutation in the rabbit OP cDNA within the Gly-Arg-Gly-Asp-Ser (GRGDS) sequence were expressed in Escherichia coli and purified to homogeneity. P388D1 cells bound rOP in a saturable manner. rOP induced adhesion and haptotaxis of P388D1 cells, whereas mutated rabbit OP (rOPmut) did not. Anti-rOP IgG F(ab′)2 and synthetic GRGDS peptide inhibited rOP-mediated adhesion and haptotaxis of P388D1 cells. Fibronectin (FN)-mediated adhesion of P388D1 cells was markedly inhibited in the presence of fluid-phase rOP. Adhesion of P388D1 cells to rOP was significantly inhibited by anti-[alpha-subunits of VLA4 (alpha 4) and VLA5 (alpha 5)] monoclonal antibodies (mAbs), but not by anti-[alpha-subunit of vitronectin (VN) receptor (alpha V) or Mac-1 (alpha M)] mAb. Adhesion of P388D1 cells to FN and VN was significantly inhibited by anti-alpha V mAb but not anti-alpha 4, -alpha 5 or -alpha M mAb. Haptotaxis of P388D1 cells to rOP was significantly inhibited by anti-alpha V mAb, but not by anti-alpha 4, -alpha 5 and alpha M mAbs, whereas that to FN showed no inhibition with all three mAbs. Haptotaxis of P388D1 cells to VN was significantly inhibited by anti-alpha 5 and -alpha V mAbs but not by anti-alpha 4 and -alpha M mAbs. Similar features of inhibition of adhesion and haptotaxis of P388D1 cells to human OP were observed by mAbs. rOP had no chemotactic effect on P388D1 cells. Significant polymorphonuclear leucocyte migration was observed 3-12 h after intradermal injection of rOP into rabbits.

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