Novel Genes Involved in Resistance to Both Ultraviolet Radiation and Perchlorate From the Metagenomes of Hypersaline Environments

Microorganisms that thrive in hypersaline environments on the surface of our planet are exposed to the harmful effects of ultraviolet radiation. Therefore, for their protection, they have sunscreen pigments and highly efficient DNA repair and protection systems. The present study aimed to identify new genes involved in UV radiation resistance from these microorganisms, many of which cannot be cultured in the laboratory. Thus, a functional metagenomic approach was used and for this, small-insert libraries were constructed with DNA isolated from microorganisms of high-altitude Andean hypersaline lakes in Argentina (Diamante and Ojo Seco lakes, 4,589 and 3,200 m, respectively) and from the Es Trenc solar saltern in Spain. The libraries were hosted in a UV radiation-sensitive strain of Escherichia coli (recA mutant) and they were exposed to UVB. The resistant colonies were analyzed and as a result, four clones were identified with environmental DNA fragments containing five genes that conferred resistance to UV radiation in E. coli. One gene encoded a RecA-like protein, complementing the mutation in recA that makes the E. coli host strain more sensitive to UV radiation. Two other genes from the same DNA fragment encoded a TATA-box binding protein and an unknown protein, both responsible for UV resistance. Interestingly, two other genes from different and remote environments, the Ojo Seco Andean lake and the Es Trenc saltern, encoded two hypothetical proteins that can be considere...
Source: Frontiers in Microbiology - Category: Microbiology Source Type: research

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Publication date: Available online 22 May 2020Source: Mutation Research/Genetic Toxicology and Environmental MutagenesisAuthor(s): Jorge Serment-Guerrero, Viridiana Dominguez-Monroy, Jenny Davila-Becerril, Enrique Morales-Avila, Jorge Fuentes-Lorenzo
Source: Mutation Research Genetic Toxicology and Environmental Mutagenesis - Category: Genetics & Stem Cells Source Type: research
AlkB is a bacterial Fe(II)– and 2-oxoglutarate–dependent dioxygenase that repairs a wide range of alkylated nucleobases in DNA and RNA as part of the adaptive response to exogenous nucleic acid–alkylating agents. Although there has been longstanding interest in the structure and specificity of Escherichia coli AlkB and its homologs, difficulties in assaying their repair activities have limited our understanding of their substrate specificities and kinetic mechanisms. Here, we used quantitative kinetic approaches to determine the transient kinetics of recognition and repair of alkylated DNA by AlkB. These ...
Source: Journal of Biological Chemistry - Category: Chemistry Authors: Tags: DNA and Chromosomes Source Type: research
Abstract BACKGROUND: Infants with gastroschisis require operations and lengthy hospitalizations due to intestinal dysmotility. Dysbiosis may contribute to these problems. Little is known on the microbiome of gastroschisis infants. METHODS: The purpose of this study was to investigate the fecal microbiome in gastroschisis infants. Microbiome profiling was performed by sequencing the V4 region of the 16S rRNA gene. The microbiome of gastroschisis infants was compared to the microbiome of healthy controls, and the effects of mode of birth delivery, gestational age, antibiotic duration, and nutrition type on micr...
Source: JPEN Journal Of Parenteral And Enteral Nutrition - Category: Nutrition Authors: Tags: JPEN J Parenter Enteral Nutr Source Type: research
Abstract Ribonucleic acid (RNA) is central to many life processes and to fulfil its function it has a substantial chemical variety of its building blocks. Enzymatic thiolation of uridine introduces 4-thiouridine (s4U) into many bacterial transfer RNAs (tRNAs) which is used as a sensor for UV radiation. A similar modified nucleoside, 2-thiocytidine, was recently found to be sulfur-methylated especially in bacteria exposed to antibiotics and simple methylating reagents. Here, we report the synthesis of 4-methylthiouridine (ms4U) and confirm its presence and additional formation under stress in E. coli. We use the sy...
Source: Chembiochem - Category: Biochemistry Authors: Tags: Chembiochem Source Type: research
Authors: Kuznetsov NA, Fedorova OS Abstract X-ray data show that DNA glycosylases, which initiate the pathway of base excision repair in DNA, belong to six structural superfamilies. Here, we provide an overview of the latest results of kinetic studies on the mechanisms of specific recognition of a damaged nucleotide at the early steps of DNA repair by human (OGG1 and MBD4) or Escherichia coli (Nth and MutY) N-DNA-glycosylases belonging to superfamily Helix-hairpin-Helix (HhH). A comparison of real-time conformational transformations of DNA glycosylases and DNA with the structural data obtained for free enzymes and ...
Source: Advances in Experimental Medicine and Biology - Category: Research Tags: Adv Exp Med Biol Source Type: research
Abstract Effects of environmental factors for growth of Escherichia coli on spontaneous mutagenesis and homologous recombination events are described. By analyzing rifampicin-resistant (Rifr) mutation frequencies in an E. coli strain lacking MutM and MutY repair enzymes, which suppress base substitution mutations caused by 8-oxoguanine (7,8 dihydro-8-oxoguanine; 8-oxoG) in DNA, we examined levels of oxidative DNA damage produced in normally growing cells. The level of 8-oxoG DNA damage was about 9- and 63-fold higher in cells grown in M9-glucose and M9-glycerol media, respectively, than in those grown in LB medium...
Source: Genes and Genetic Systems - Category: Genetics & Stem Cells Authors: Tags: Genes Genet Syst Source Type: research
Hydrogen peroxide is the preeminent chemical weapon that organisms use for combat. Individual cells rely on conserved defenses to prevent and repair peroxide-induced damage, but whether similar defenses might be coordinated across cells in animals remains poorly understood. Here, we identify a neuronal circuit in the nematodeCaenorhabditis elegans that processes information perceived by two sensory neurons to control the induction of hydrogen peroxide defenses in the organism. We found that catalases produced byEscherichia coli, the nematode's food source, can deplete hydrogen peroxide from the local environment and thereb...
Source: eLife - Category: Biomedical Science Tags: Developmental Biology Neuroscience Source Type: research
In this study, a C69-family cysteine dipeptidase of the entomopathogenic fungus Metarhizium acridum, MaPepDA, was expressed in Escherichia coli. The purified enzyme had a molecular mass of 56-kDa, and displayed a high activity to dipeptide substrate with an optimal Ala-Gln hydrolytic activity at about pH 6.0 and 55°C. It was demonstrated that MaPepDA is an intracellular dipeptidase localized in the cytosol, and that it is expressed during the whole fungal growth. Disruption of the MaPepDA gene increased conidial germination, growth rate, and significantly improved the tolerance to UV-B and heat stress in M. acridum. Ho...
Source: Frontiers in Microbiology - Category: Microbiology Source Type: research
Abstract Developing wound dressing that inhibits bacterial infection for treating complex wound healing processes has been a research hotspot. Here, we report the fabrication of Cu-MOFs (HKUST-1) incorporated electrospun chitosan/polyvinyl alcohol (HKUST-1/chitosan/PVA) fibers through the blending electrospinning for wound therapy. HKUST-1/chitosan/PVA fibers displayed satisfying physical properties, such as mechanical property, water uptake, water vapor transmission rate, etc. Cytotoxicity test indicated that HKUST-1/chitosan/PVA fibers were biocompatible and could support cell adhesion. Due to the HKUST-1 incorp...
Source: International Journal of Biological Macromolecules - Category: Biochemistry Authors: Tags: Int J Biol Macromol Source Type: research
co In Escherichia coli, DNA replication forks stall on average once per cell cycle. When this occurs, replisome components disengage from the DNA, exposing an intact, or nearly intact fork. Consequently, the fork structure must be regressed away from the initial impediment so that repair can occur. Regression is catalyzed by the powerful, monomeric DNA helicase, RecG. During this reaction, the enzyme couples unwinding of fork arms to rewinding of duplex DNA resulting in the formation of a Holliday junction. RecG works against large opposing forces enabling it to clear the fork of bound proteins. Following subsequent pr...
Source: Genes - Category: Genetics & Stem Cells Authors: Tags: Review Source Type: research
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