Mutagenesis and More: umuDC and the Escherichia coli SOS Response

Genetics ◽  
1998 ◽  
Vol 148 (4) ◽  
pp. 1599-1610 ◽  
Author(s):  
Bradley T Smith ◽  
Graham C Walker
Keyword(s):  
Escherichia Coli ◽  
Dna Damage ◽  
Cellular Response ◽  
Sos Response ◽  
Posttranslational Regulation ◽  
E Coli ◽  
Sos Mutagenesis ◽  
Induced Mutagenesis ◽  
Mechanistic Basis ◽  
Increase Cell Survival

Abstract The cellular response to DNA damage that has been most extensively studied is the SOS response of Escherichia coli. Analyses of the SOS response have led to new insights into the transcriptional and posttranslational regulation of processes that increase cell survival after DNA damage as well as insights into DNA-damage-induced mutagenesis, i.e., SOS mutagenesis. SOS mutagenesis requires the recA and umuDC gene products and has as its mechanistic basis the alteration of DNA polymerase III such that it becomes capable of replicating DNA containing miscoding and noncoding lesions. Ongoing investigations of the mechanisms underlying SOS mutagenesis, as well as recent observations suggesting that the umuDC operon may have a role in the regulation of the E. coli cell cycle after DNA damage has occurred, are discussed.

scholarly journals Deuterium oxide enhances the SOS response of Escherichia coli induced by bactericidal agents

2020 ◽  
pp. 79-80
Author(s):  
С.В. Смирнова ◽  
Т.Н. Шапиро ◽  
Е.В. Игонина ◽  
С.К. Абилев
Keyword(s):  
Escherichia Coli ◽  
Dna Damage ◽  
Nalidixic Acid ◽  
Deuterium Oxide ◽  
Gene Promoter ◽  
Sos Response ◽  
Genotoxic Effect ◽  
E Coli ◽  
Lux Biosensor ◽  
First Time

Изучали генотоксическое действие бактерицидных средств диоксидина, фурацилина и налидиксовой кислоты на клетки дейтерированной культуры lux-биосенсора E.coli MG1655 (pColD::lux), люминесцирующего в результате активации промотора гена колицина colD в ответ на повреждение ДНК. Впервые показано, что оксид дейтерия (D2O) в концентрации 9% усиливает SOS-ответ, индуцированный исследуемыми лекарственными препаратами, в 1,6-2,8 раза в клетках E. coli. We studied the genotoxic effect of bactericidal agents: dioxine, furaciline and nalidixic acid on cells of the deuterated culture lux-biosensor E. coli MG1655 (pColD::lux), which luminesces as a result of activation of the colicin gene promoter colD in response to DNA damage. For the first time, it was shown that deuterium oxide (D2O) at a concentration of 9% increases the SOS response by 1.6-2.8 times in E. coli cells induced by the studied drugs.

scholarly journals Inactivation of Umuc Protein Significantly Reduces Resistance to Ciprofloxacin and SOS Mutagenesis in Escherichia coli Mutants Harboring Intact Umud Gene

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Razieh Pourahmad Jaktaji ◽  
Sayedeh Marzieh Nourbakhsh Rezaei
Keyword(s):  
Escherichia Coli ◽  
Dna Polymerase ◽  
Genetic Background ◽  
Pcr Amplification ◽  
Sos Response ◽  
Rpob Gene ◽  
Dilution Method ◽  
E Coli ◽  
Sos Mutagenesis ◽  
Dna Polymerase V

Background: Ciprofloxacin induces SOS response and mutagenesis by activation of UmuD’2C (DNA polymerase V) and DinB (DNA polymerase IV) in Escherichia coli, leading to antibiotic resistance during therapy. Inactivation of DNA polymerase V can result in the inhibition of mutagenesis in E. coli. Objectives: The aim of this research was to investigate the effect of UmuC inactivation on resistance to ciprofloxacin and SOS mutagenesis in E. coli mutants. Methods: Ciprofloxacin-resistant mutants were produced in a umuC- genetic background in the presence of increasing concentrations of ciprofloxacin. The minimum inhibitory concentration of umuC-mutants was measured by broth dilution method. Alterations in the rifampin resistance-determing region of rpoB gene were assessed by PCR amplification and DNA sequencing. The expression of SOS genes was measured by quantitative real-time PCR assay. Results: Results showed that despite the induction of SOS response (overexpression of recA, dinB, and umuD genes) following exposure to ciprofloxacin in E. coliumuC mutants, resistance to ciprofloxacin and SOS mutagenesis significantly decreased. However, rifampicin-resistant clones emerged in this genetic background. One of these clones showed mutations in the rifampicin resistance-determining region of rpoB (cluster II). The low mutation frequency of E. coli might be associated with the presence and overexpression of umuD gene, which could somehow limit the activity of DinB, the location and type of mutations in the β subunit of RNA polymerase. Conclusions: In conclusion, for increasing the efficiency of ciprofloxacin against Gram-negative bacteria, use of an inhibitor of umuC, along with ciprofloxacin, would be helpful.

scholarly journals An SOS Response Induced by High Pressure in Escherichia coli

2004 ◽  
Vol 186 (18) ◽  
pp. 6133-6141 ◽  
Author(s):  
Abram Aertsen ◽  
Rob Van Houdt ◽  
Kristof Vanoirbeek ◽  
Chris W. Michiels
Keyword(s):  
Escherichia Coli ◽  
Dna Damage ◽  
Current Knowledge ◽  
Sos Response ◽  
Fluorescence Induction ◽  
Food Preservation ◽  
E Coli ◽  
Mediated Effects ◽  
Bona Fide ◽  
First Time

ABSTRACT Although pressure is an important environmental parameter in microbial niches such as the deep sea and is furthermore used in food preservation to inactivate microorganisms, the fundamental understanding of its effects on bacteria remains fragmentary. Our group recently initiated differential fluorescence induction screening to search for pressure-induced Escherichia coli promoters and has already reported induction of the heat shock regulon. Here the screening was continued, and we report for the first time that pressure induces a bona fide SOS response in E. coli, characterized by the RecA and LexA-dependent expression of uvrA, recA, and sulA. Moreover, it was shown that pressure is capable of triggering lambda prophage induction in E. coli lysogens. The remnant lambdoid e14 element, however, could not be induced by pressure, as opposed to UV irradiation, indicating subtle differences between the pressure-induced and the classical SOS response. Furthermore, the pressure-induced SOS response seems not to be initiated by DNA damage, since ΔrecA and lexA1 (Ind−) mutants, which are intrinsically hypersensitive to DNA damage, were not sensitized or were only very slightly sensitized for pressure-mediated killing and since pressure treatment was not found to be mutagenic. In light of these findings, the current knowledge of pressure-mediated effects on bacteria is discussed.

scholarly journals The Escherichia coli SOS Response: Much More than DNA Damage Repair

2021 ◽  
Author(s):  
Zdravko Podlesek ◽  
Darja Žgur Bertok
Keyword(s):  
Escherichia Coli ◽  
Dna Damage ◽  
Dna Damage Repair ◽  
Sos Response ◽  
Genetic Adaptation ◽  
Repair Pathway ◽  
E Coli ◽  
Bacterial Pathogenicity ◽  
Damage Repair ◽  
Regulator Genes

The Escherichia coli SOS response is an inducible DNA damage repair pathway controlled by two key regulators, LexA, a repressor and RecA, an inducer. Upon DNA damage RecA is activated and stimulates self cleavage of LexA, leading to, in E. coli, derepresion of approximately 50 SOS genes. The response is triggered by exogenous and endogenous signals that bacteria encounter at a number of sites within the host. Nevertheless, besides regulating DNA damage repair the SOS response plays a much broader role. Thus, SOS error prone polymerases promote elevated mutation rates significant for genetic adaptation and diversity, including antibiotic resistance. Here we review the E. coli SOS response in relation to recalcitrance to antimicrobials, including persister and biofilm formation, horizontal gene tranfer, gene mobility, bacterial pathogenicity, as well SOS induced bacteriocins that drive diversification. Phenotypic heterogeneity in expression of the SOS regulator genes, recA and lexA as well as colicin activity genes is also discussed.

scholarly journals Aberrant repair initiated by the adenine-DNA glycosylase does not play a role in UV-induced mutagenesis in Escherichia coli

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e6029 ◽  
Author(s):  
Caroline Zutterling ◽  
Aibek Mursalimov ◽  
Ibtissam Talhaoui ◽  
Zhanat Koshenov ◽  
Zhiger Akishev ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Dna Damage ◽  
Dna Repair ◽  
Uv Irradiation ◽  
Genome Stability ◽  
Dna Duplexes ◽  
E Coli ◽  
Dna Strands ◽  
Induced Mutagenesis

Background DNA repair is essential to counteract damage to DNA induced by endo- and exogenous factors, to maintain genome stability. However, challenges to the faithful discrimination between damaged and non-damaged DNA strands do exist, such as mismatched pairs between two regular bases resulting from spontaneous deamination of 5-methylcytosine or DNA polymerase errors during replication. To counteract these mutagenic threats to genome stability, cells evolved the mismatch-specific DNA glycosylases that can recognize and remove regular DNA bases in the mismatched DNA duplexes. The Escherichia coli adenine-DNA glycosylase (MutY/MicA) protects cells against oxidative stress-induced mutagenesis by removing adenine which is mispaired with 7,8-dihydro-8-oxoguanine (8oxoG) in the base excision repair pathway. However, MutY does not discriminate between template and newly synthesized DNA strands. Therefore the ability to remove A from 8oxoG•A mispair, which is generated via misincorporation of an 8-oxo-2′-deoxyguanosine-5′-triphosphate precursor during DNA replication and in which A is the template base, can induce A•T→C•G transversions. Furthermore, it has been demonstrated that human MUTYH, homologous to the bacterial MutY, might be involved in the aberrant processing of ultraviolet (UV) induced DNA damage. Methods Here, we investigated the role of MutY in UV-induced mutagenesis in E. coli. MutY was probed on DNA duplexes containing cyclobutane pyrimidine dimers (CPD) and pyrimidine (6–4) pyrimidone photoproduct (6–4PP). UV irradiation of E. coli induces Save Our Souls (SOS) response characterized by increased production of DNA repair enzymes and mutagenesis. To study the role of MutY in vivo, the mutation frequencies to rifampicin-resistant (RifR) after UV irradiation of wild type and mutant E. coli strains were measured. Results We demonstrated that MutY does not excise Adenine when it is paired with CPD and 6–4PP adducts in duplex DNA. At the same time, MutY excises Adenine in A•G and A•8oxoG mispairs. Interestingly, E. coli mutY strains, which have elevated spontaneous mutation rate, exhibited low mutational induction after UV exposure as compared to MutY-proficient strains. However, sequence analysis of RifR mutants revealed that the frequencies of C→T transitions dramatically increased after UV irradiation in both MutY-proficient and -deficient E. coli strains. Discussion These findings indicate that the bacterial MutY is not involved in the aberrant DNA repair of UV-induced DNA damage.

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.

scholarly journals Quorum Sensing Is a Global Regulatory Mechanism in Enterohemorrhagic Escherichia coli O157:H7

2001 ◽  
Vol 183 (17) ◽  
pp. 5187-5197 ◽  
Author(s):  
Vanessa Sperandio ◽  
Alfredo G. Torres ◽  
Jorge A. Girón ◽  
James B. Kaper
Keyword(s):  
Escherichia Coli ◽  
Quorum Sensing ◽  
Type Strain ◽  
Wild Type Strain ◽  
Regulatory Mechanism ◽  
Sos Response ◽  
Enterohemorrhagic Escherichia Coli ◽  
Trna Genes ◽  
Wild Type ◽  
E Coli

ABSTRACT Enterohemorrhagic Escherichia coli (EHEC) O157:H7 is responsible for outbreaks of bloody diarrhea and hemolytic-uremic syndrome in many countries. EHEC virulence mechanisms include the production of Shiga toxins (Stx) and formation of attaching and effacing (AE) lesions on intestinal epithelial cells. We recently reported that genes involved in the formation of the AE lesion were regulated by quorum sensing through autoinducer-2, which is synthesized by the product of the luxS gene. In this study we hybridized an E. coli gene array with cDNA synthesized from RNA that was extracted from EHEC strain 86-24 and its isogenicluxS mutant. We observed that 404 genes were regulated by luxS at least fivefold, which comprises approximately 10% of the array genes; 235 of these genes were up-regulated and 169 were down-regulated in the wild-type strain compared to in theluxS mutant. Down-regulated genes included several involved in cell division, as well as ribosomal and tRNA genes. Consistent with this pattern of gene expression, theluxS mutant grows faster than the wild-type strain (generation times of 37.5 and 60 min, respectively, in Dulbecco modified Eagle medium). Up-regulated genes included several involved in the expression and assembly of flagella, motility, and chemotaxis. Using operon::lacZ fusions to class I, II, and III flagellar genes, we were able to confirm this transcriptional regulation. We also observed fewer flagella by Western blotting and electron microscopy and decreased motility halos in semisolid agar in the luxS mutant. The average swimming speeds for the wild-type strain and the luxS mutant are 12.5 and 6.6 μm/s, respectively. We also observed an increase in the production of Stx due to quorum sensing. Genes encoding Stx, which are transcribed along with λ-like phage genes, are induced by an SOS response, and genes involved in the SOS response were also regulated by quorum sensing. These results indicate that quorum sensing is a global regulatory mechanism for basic physiological functions of E. coli as well as for virulence factors.

scholarly journals Characterization of Escherichia coli DNA Lesions Generated within J774 Macrophages

2000 ◽  
Vol 182 (18) ◽  
pp. 5225-5230 ◽  
Author(s):  
Eliana Schlosser-Silverman ◽  
Maya Elgrably-Weiss ◽  
Ilan Rosenshine ◽  
Ron Kohen ◽  
Shoshy Altuvia
Keyword(s):  
Escherichia Coli ◽  
Dna Damage ◽  
Respiratory Burst ◽  
Defense Mechanism ◽  
Dna Lesions ◽  
Intracellular Bacteria ◽  
Bacterial Killing ◽  
Strand Breaks ◽  
E Coli ◽  
Dna Strand

ABSTRACT Macrophages are armed with multiple oxygen-dependent and -independent bactericidal properties. However, the respiratory burst, generating reactive oxygen species, is believed to be a major cause of bacterial killing. We exploited the susceptibility of Escherichia coli in macrophages to characterize the effects of the respiratory burst on intracellular bacteria. We show that E. coli strains recovered from J774 macrophages exhibit high rates of mutations. We report that the DNA damage generated inside macrophages includes DNA strand breaks and the modification 8-oxo-2′-deoxyguanosine, which are typical oxidative lesions. Interestingly, we found that under these conditions, early in the infection the majority of E. coli cells are viable but gene expression is inhibited. Our findings demonstrate that macrophages can cause severe DNA damage to intracellular bacteria. Our results also suggest that protection against the macrophage-induced DNA damage is an important component of the bacterial defense mechanism within macrophages.

scholarly journals A newly identified prophage-encoded gene, ymfM, causes SOS-inducible filamentation in Escherichia coli

2021 ◽  
Author(s):  
Shirin Ansari ◽  
James C. Walsh ◽  
Amy L. Bottomley ◽  
Iain G. Duggin ◽  
Catherine Burke ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Cell Division ◽  
Pathogenic Bacteria ◽  
Bacterial Resistance ◽  
Sos Response ◽  
E Coli ◽  
Ring Assembly ◽  
Multiple Alternative ◽  
Z Ring ◽  
Cell Division Inhibitor

Rod-shaped bacteria such as Escherichia coli can regulate cell division in response to stress, leading to filamentation, a process where cell growth and DNA replication continues in the absence of division, resulting in elongated cells. The classic example of stress is DNA damage which results in the activation of the SOS response. While the inhibition of cell division during SOS has traditionally been attributed to SulA in E. coli, a previous report suggests that the e14 prophage may also encode an SOS-inducible cell division inhibitor, previously named SfiC. However, the exact gene responsible for this division inhibition has remained unknown for over 35 years. A recent high-throughput over-expression screen in E. coli identified the e14 prophage gene, ymfM, as a potential cell division inhibitor. In this study, we show that the inducible expression of ymfM from a plasmid causes filamentation. We show that this expression of ymfM results in the inhibition of Z ring formation and is independent of the well characterised inhibitors of FtsZ ring assembly in E. coli, SulA, SlmA and MinC. We confirm that ymfM is the gene responsible for the SfiC phenotype as it contributes to the filamentation observed during the SOS response. This function is independent of SulA, highlighting that multiple alternative division inhibition pathways exist during the SOS response. Our data also highlight that our current understanding of cell division regulation during the SOS response is incomplete and raises many questions regarding how many inhibitors there actually are and their purpose for the survival of the organism. Importance: Filamentation is an important biological mechanism which aids in the survival, pathogenesis and antibiotic resistance of bacteria within different environments, including pathogenic bacteria such as uropathogenic Escherichia coli. Here we have identified a bacteriophage-encoded cell division inhibitor which contributes to the filamentation that occurs during the SOS response. Our work highlights that there are multiple pathways that inhibit cell division during stress. Identifying and characterising these pathways is a critical step in understanding survival tactics of bacteria which become important when combating the development of bacterial resistance to antibiotics and their pathogenicity.

scholarly journals Cellular response to DNA damage is enhanced by the pR plasmid in mouse cells and in Escherichia coli.

1986 ◽  
Vol 6 (2) ◽  
pp. 586-592 ◽  
Author(s):  
L Marcucci ◽  
F Gigliani ◽  
P A Battaglia ◽  
R Bosi ◽  
E Sporeno ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Dna Damage ◽  
Statistical Analysis ◽  
Cellular Response ◽  
Regulatory Mechanism ◽  
Uv Light ◽  
Transformed Cells ◽  
Insertion Mutagenesis ◽  
Mouse Cells ◽  
Inducible Repair

The pR plasmid, which enhances the survival of Escherichia coli C600 exposed to UV light by induction of the SOS regulatory mechanism, showed the same effect when it transformed mouse LTA cells (tk-, aprt-). With Tn5 insertion mutagenesis which inactivates UV functions in the pR plasmid, we recognized two different regions of the plasmid, uvp1 and uvp2. These pR UVR- mutants exhibited the same effect in LTA transformed cells, demonstrating that resistance to UV light, carried by the pR plasmid, was really due to the expression of these two regions, which were also in the mouse cells. Statistical analysis showed that the expression of the uvp1 and uvp2 regions significantly increased (P less than 0.01) the survival upon exposure to UV light in mouse cells and bacteria. These results might suggest the presence of an inducible repair response to DNA damage in mouse LTA cells.

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