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Shiou-Chi Chang, Uthpala I Seneviratne, Jie Wu, Natalia Tretyakova, John M Essigmann
The adverse effects of the human carcinogen 1,3-butadiene (BD) are believed to be mediated by its DNA-reactive metabolites such as 3,4-epoxybut-1-ene (EB) and 1,2,3,4-diepoxybutane (DEB). The specific DNA adducts responsible for toxic and mutagenic effects of BD, however, have yet to be identified. Recent in vitro polymerase bypass studies of BD-induced adenine (BD-dA) adducts show that DEB-induced N(6),N(6)-DHB-dA (DHB = 2,3-dihydroxybutan-1,4-diyl) and 1,N(6)-γ-HMHP-dA (HMHP = 2-hydroxy-3-hydroxymethylpropan-1,3-diyl) adducts block replicative DNA polymerases but are bypassed by human polymerases η and κ, leading to point mutations and deletions...
April 17, 2017: Chemical Research in Toxicology
Aníbal Marcelo Reyes, Brandán Pedre Pérez, María Inés De Armas, Maria-Armineh Tossounian, Rafael Radi, Joris Messens, Madia Trujillo
SIGNIFICANCE: Mycothiol (MSH, AcCys-GlcN-Ins) is the main low molecular weight thiol of most Actinomycetes, including the human pathogen Mycobacterium tuberculosis that affects millions of people worldwide. Strains with decreased MSH content show increased susceptibilities to hydroperoxides and electrophilic compounds. In M. tuberculosis, MSH modulates the response to several anti-tuberculosis drugs. Enzymatic routes involving MSH could provide clues for specific drug design. Recent Advances...
April 3, 2017: Antioxidants & Redox Signaling
Bénédicte Michel, Anurag Kumar Sinha
The Escherichia coli holD mutant is poorly viable because the stability of holoenzyme polymerase III (Pol III HE) on DNA is compromised. Consequently, the SOS response is induced and the SOS polymerases DinB and Pol II further hinder replication. Mutations that restore the holD mutant viability belong to two classes, those that stabilize Pol III on DNA and those that prevent the deleterious effects of DinB over-production. We identified a dnaX mutation and the inactivation of rfaP and sspA genes as belonging to the first class of holD mutant suppressors...
March 25, 2017: Molecular Microbiology
Tommy F Tashjian, Ida Lin, Verena Belt, Tiziana M Cafarelli, Veronica G Godoy
In Escherichia coli the highly conserved DNA damage regulated dinB gene encodes DNA Polymerase IV (DinB), an error prone specialized DNA polymerase with a central role in stress-induced mutagenesis. Since DinB is the DNA polymerase with the highest intracellular concentrations upon induction of the SOS response, further regulation must exist to maintain genomic stability. Remarkably, we find that DinB DNA synthesis is inherently poor when using an RNA primer compared to a DNA primer, while high fidelity DNA polymerases are known to have no primer preference...
2017: Frontiers in Microbiology
Tatjana Jatsenko, Julia Sidorenko, Signe Saumaa, Maia Kivisaar
Translesion DNA synthesis (TLS), facilitated by low-fidelity polymerases, is an important DNA damage tolerance mechanism. Here, we investigated the role and biological function of TLS polymerase ImuC (former DnaE2), generally present in bacteria lacking DNA polymerase V, and TLS polymerase DinB in response to DNA alkylation damage in Pseudomonas aeruginosa and P. putida. We found that TLS DNA polymerases ImuC and DinB ensured a protective role against N- and O-methylation induced by N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) in both P...
2017: PloS One
Ruiqi Zhang, Bingxiao Sun, Juan Chen, Aizhong Cao, Liping Xing, Yigao Feng, Caixia Lan, Peidu Chen
Powdery mildew resistance gene Pm55 was physically mapped to chromosome arm 5VS FL 0.60-0.80 of Dasypyrum villosum . Pm55 is present in T5VS·5AL and T5VS·5DL translocations, which should be valuable resources for wheat improvement. Powdery mildew caused by Blumeria graminis f. sp. tritici is a major wheat disease worldwide. Exploiting novel genes effective against powdery mildew from wild relatives of wheat is a promising strategy for controlling this disease. To identify novel resistance genes for powdery mildew from Dasypyrum villosum, a wild wheat relative, we evaluated a set of Chinese Spring-D...
October 2016: TAG. Theoretical and Applied Genetics. Theoretische und Angewandte Genetik
Adeline Durand, Anurag Kumar Sinha, Cloelia Dard-Dascot, Bénédicte Michel
Mutants lacking the ψ (HolD) subunit of the Escherichia coli DNA Polymerase III holoenzyme (Pol III HE) have poor viability, but a residual growth allows the isolation of spontaneous suppressor mutations that restore ΔholD mutant viability. Here we describe the isolation and characterization of two suppressor mutations in the trkA and trkE genes, involved in the main E. coli potassium import system. Viability of ΔholD trk mutants is abolished on media with low or high K+ concentrations, where alternative K+ import systems are activated, and is restored on low K+ concentrations by the inactivation of the alternative Kdp system...
June 2016: PLoS Genetics
Jonathan D Taylor, Gabrielle Taylor, Stephen A Hare, Steve J Matthews
Bacteria have developed a variety of mechanisms for surviving harsh environmental conditions, nutrient stress and overpopulation. Paenibacillus dendritiformis produces a lethal protein (Slf) that is able to induce cell death in neighbouring colonies and a phenotypic switch in more distant ones. Slf is derived from the secreted precursor protein, DfsB, after proteolytic processing. Here, we present new crystal structures of DfsB homologues from a variety of bacterial species and a surprising version present in the yeast Saccharomyces cerevisiae...
February 13, 2016: Journal of Molecular Biology
Shreya Ghosh, Sourabh Samaddar, Prithwiraj Kirtania, Sujoy K Das Gupta
UNLABELLED: Mycobacterium species such as M. smegmatis and M. tuberculosis encode at least two translesion synthesis (TLS) polymerases, DinB1 and DinB2, respectively. Although predicted to be linked to DNA repair, their role in vivo remains enigmatic. M. smegmatis mc(2)155, a strain commonly used to investigate mycobacterial genetics, has two copies of dinB2, the gene that codes for DinB2, by virtue of a 56-kb chromosomal duplication. Expression of a mycobacteriophage D29 gene (gene 50) encoding a class II ribonucleotide reductase in M...
January 2016: Journal of Bacteriology
Michelle K Scotland, Justin M H Heltzel, James E Kath, Jung-Suk Choi, Anthony J Berdis, Joseph J Loparo, Mark D Sutton
Translesion DNA synthesis (TLS) by specialized DNA polymerases (Pols) is a conserved mechanism for tolerating replication blocking DNA lesions. The actions of TLS Pols are managed in part by ring-shaped sliding clamp proteins. In addition to catalyzing TLS, altered expression of TLS Pols impedes cellular growth. The goal of this study was to define the relationship between the physiological function of Escherichia coli Pol IV in TLS and its ability to impede growth when overproduced. To this end, 13 novel Pol IV mutants were identified that failed to impede growth...
September 2015: PLoS Genetics
Lisa A Hawver, Mohammad Tehrani, Nicole M Antczak, Danielle Kania, Stephanie Muser, Jana Sefcikova, Penny J Beuning
Y-family DNA polymerases are important for conferring cellular resistance to DNA damaging agents in part due to their specialized ability to copy damaged DNA. The Escherichia coli Y-family DNA polymerases are encoded by the umuDC and dinB genes. UmuC and the cleaved form of UmuD, UmuD', form UmuD'2C (pol V), which is able to bypass UV photoproducts such as cyclobutane pyrimidine dimers and 6-4 thymine-thymine dimers, whereas DinB is specialized to copy N(2)-dG adducts, such as N(2)-furfuryl-dG. To better understand this inherent specificity, we used hydroxylamine to generate a random library of UmuC variants from which we then selected those with the ability to confer survival to nitrofurazone (NFZ), which is believed to cause N(2)-furfuryl-dG lesions...
October 2015: Mutation Research
Sean L Moro, Melanie J Cocco
The dinB homolog (Dbh) is a member of the Y-family of translesion DNA polymerases, which are specialized to accurately replicate DNA across from a wide variety of lesions in living cells. Lesioned bases block the progression of high-fidelity polymerases and cause detrimental replication fork stalling; Y-family polymerases can bypass these lesions. The active site of the translesion synthesis polymerase is more open than that of a replicative polymerase; consequently Dbh polymerizes with low fidelity. Bypass polymerases also have low processivity...
October 2015: Biomolecular NMR Assignments
Masashi Uchiyama, Junko Terunuma, Fumio Hanaoka
Translesion DNA synthesis provides an alternative DNA replication mechanism when template DNA is damaged. In fission yeast, Eso1 (polη), Kpa1/DinB (polκ), Rev1, and Polζ (a complex of Rev3 and Rev7) have been identified as translesion synthesis polymerases. The enzymatic characteristics and protein-protein interactions of these polymerases have been intensively characterized; however, how these proteins are regulated during the cell cycle remains unclear. Therefore, we examined the cell cycle oscillation of translesion polymerases...
2015: PloS One
Linjiang Zhu, Yin Li, Zhen Cai
BACKGROUND: Microbial tolerance to different environmental stresses is of importance for efficient production of biofuels and biochemical. Such traits are often improved by evolutionary engineering approaches including mutagen-induced mutagenesis and successive passage. In contrast to these approaches which generate mutations in rapidly growing cells, recent research showed that mutations could be generated in non-dividing cells under stressful but non-lethal conditions, leading to the birth of the theory of stress-induced mutagenesis (SIM)...
2015: Biotechnology for Biofuels
Sophie Maisnier-Patin, John R Roth
Selection detects mutants but does not cause mutations. Contrary to this dictum, Cairns and Foster plated a leaky lac mutant of Escherichia coli on lactose medium and saw revertant (Lac(+)) colonies accumulate with time above a nongrowing lawn. This result suggested that bacteria might mutagenize their own genome when growth is blocked. However, this conclusion is suspect in the light of recent evidence that revertant colonies are initiated by preexisting cells with multiple copies the conjugative F'lac plasmid, which carries the lac mutation...
July 2015: Cold Spring Harbor Perspectives in Biology
Sarita Mallik, Ellen M Popodi, Andrew J Hanson, Patricia L Foster
UNLABELLED: Escherichia coli's DNA polymerase IV (Pol IV/DinB), a member of the Y family of error-prone polymerases, is induced during the SOS response to DNA damage and is responsible for translesion bypass and adaptive (stress-induced) mutation. In this study, the localization of Pol IV after DNA damage was followed using fluorescent fusions. After exposure of E. coli to DNA-damaging agents, fluorescently tagged Pol IV localized to the nucleoid as foci. Stepwise photobleaching indicated ∼60% of the foci consisted of three Pol IV molecules, while ∼40% consisted of six Pol IV molecules...
September 2015: Journal of Bacteriology
Shiou-chi Chang, Bogdan I Fedeles, Jie Wu, James C Delaney, Deyu Li, Linlin Zhao, Plamen P Christov, Emily Yau, Vipender Singh, Marco Jost, Catherine L Drennan, Lawrence J Marnett, Carmelo J Rizzo, Stuart S Levine, F Peter Guengerich, John M Essigmann
Etheno DNA adducts are a prevalent type of DNA damage caused by vinyl chloride (VC) exposure and oxidative stress. Etheno adducts are mutagenic and may contribute to the initiation of several pathologies; thus, elucidating the pathways by which they induce cellular transformation is critical. Although N(2),3-ethenoguanine (N(2),3-εG) is the most abundant etheno adduct, its biological consequences have not been well characterized in cells due to its labile glycosidic bond. Here, a stabilized 2'-fluoro-2'-deoxyribose analog of N(2),3-εG was used to quantify directly its genotoxicity and mutagenicity...
June 23, 2015: Nucleic Acids Research
Deepti Appukuttan, Ho Seong Seo, Sunwook Jeong, Sunghun Im, Minho Joe, Dusup Song, Jungjoon Choi, Sangyong Lim
In order to understand the mechanism governing radiation resistance in Deinococcus radiodurans, current efforts are aimed at identifying potential candidates from a large repertoire of unique Deinococcal genes and protein families. DR0053 belongs to the DinB/YfiT protein family, which is an over-represented protein family in D. radiodurans. We observed that dr0053 transcript levels were highly induced in response to gamma radiation (γ-radiation) and mitomycin C (MMC) exposure depending on PprI, RecA and the DrtR/S two-component signal transduction system...
2015: PloS One
Philip Nevin, John R Engen, Penny J Beuning
Discrimination against ribonucleotides by DNA polymerases is critical to preserve DNA integrity. For many DNA polymerases, including those of the Y family, rNTP discrimination has been attributed to steric clashes between a residue near the active site, the steric gate, and the 2'-hydroxyl of the incoming rNTP. Here we used hydrogen/deuterium exchange (HDX) mass spectrometry (MS) to probe the effects of the steric gate in the Y-family DNA polymerases Escherichia coli DinB and human DNA pol κ. Formation of a ternary complex with a G:dCTP base pair in the active site resulted in slower hydrogen exchange relative to a ternary complex with G:rCTP in the active site...
May 2015: DNA Repair
Kang Wei Tan, Tuan Minh Pham, Asako Furukohri, Hisaji Maki, Masahiro Tatsumi Akiyama
The SOS response is a DNA damage response pathway that serves as a general safeguard of genome integrity in bacteria. Extensive studies of the SOS response in Escherichia coli have contributed to establishing the key concepts of cellular responses to DNA damage. However, how the SOS response impacts on the dynamics of DNA replication fork movement remains unknown. We found that inducing the SOS response decreases the mean speed of individual replication forks by 30-50% in E. coli cells, leading to a 20-30% reduction in overall DNA synthesis...
February 18, 2015: Nucleic Acids Research
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