The Escherichia coli alkA Gene Is Activated to Alleviate Mutagenesis by an Oxidized Deoxynucleoside

The cellular methyl donor S-adenosylmethionine (SAM) and other endo/exogenous agents methylate DNA bases non-enzymatically into products interfering with replication and transcription. An important product is 3-methyladenine (m3A), which in Escherichia coli is removed by m3A-DNA glycosylase I (Tag) and II (AlkA). The tag gene is constitutively expressed, while alkA is induced by sub-lethal concentrations of methylating agents. We previously found that AlkA exhibits activity for the reactive oxygen-induced thymine (T) lesion 5-formyluracil (fU) in vitro. Here, we provide evidence for AlkA involvement in the repair of oxidized bases by showing that the adenine (A) ⋅ T → guanine (G) ⋅ cytosine (C) mutation rate increased 10-fold in E. coli wild-type and alkA– cells exposed to 0.1 mM 5-formyl-2′-deoxyuridine (fdU) compared to a wild-type specific reduction of the mutation rate at 0.2 mM fdU, which correlated with alkA gene induction. G⋅C → A⋅T alleviation occurred without alkA induction (at 0.1 mM fdU), correlating with a much higher AlkA efficiency for fU opposite to G than for that to A. The common keto form of fU is the AlkA substrate. Mispairing with G by ionized fU is favored by its exclusion from the AlkA active site.
Source: Frontiers in Microbiology - Category: Microbiology Source Type: research

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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 ...
Source: Frontiers in Microbiology - Category: Microbiology Source Type: research
AbstractThe family of AlkB homolog (ALKBH) proteins, the homologs ofEscherichia coli AlkB 2 ‐oxoglutarate (2OG), and Fe(II)‐dependent dioxygenase are involved in a number of important regulatory processes in eukaryotic cells including repair of alkylation lesions in DNA, RNA, and nucleoprotein complexes. There are nine human and thirteenArabidopsis thaliana ALKBH proteins described, which exhibit diversified functions. Among them, human ALKBH5 and FaT mass and Obesity ‐associated (FTO) protein and Arabidopsis ALKBH9B and ALKBH10B have been recognized as N6 methyladenine (N6meA) demethylases, the most abundant posttra...
Source: IUBMB Life - Category: Research Authors: Tags: SPECIAL ISSUE Source Type: research
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Source: Biomed Res - Category: Research Authors: Tags: J Biomed Mater Res A Source Type: research
Abstract BACKGROUND: Ubiquitin (Ub) and Ub-like proteins (Ub-L) are critical regulators of complex cellular processes such as the cell cycle, DNA repair, transcription, chromatin remodeling, signal translation, and protein degradation. Giardia intestinalis possesses an experimentally proven Ub-conjugation system; however, a limited number of enzymes involved in this process were identified using basic local alignment search tool (BLAST). This is due to the limitations of BLAST's ability to identify homologous functional regions when similarity between the sequences dips to
Source: Memorias do Instituto Oswaldo Cruz - Category: Infectious Diseases Authors: Tags: Mem Inst Oswaldo Cruz Source Type: research
In conclusion, taller body height at the entry to adulthood, supposed to be a marker of early-life environment, is associated with lower risk of dementia diagnosis later in life. The association persisted when adjusted for educational level and intelligence test scores in young adulthood, suggesting that height is not just acting as an indicator of cognitive reserve. A Comparison of Biological Age Measurement Approaches Researchers here assess the performance of a range of approaches to measuring biological...
Source: Fight Aging! - Category: Research Authors: Tags: Newsletters Source Type: blogs
Publication date: May 2020Source: Materials Science and Engineering: C, Volume 110Author(s): Ajinkya A. Shitole, Piyush Raut, Prabhanjan Giram, Priyanka Rade, Anand Khandwekar, Baijayantimala Garnaik, Neeti SharmaAbstractFacilitating the process of wound healing and effective treatment of wounds remains a serious challenge in healthcare. Wound dressing materials play a major role in the protection of wounds and in accelerating the natural healing process. In the present study, novel core/shell (c/s) nanofibrous mats of poly(vinyl pyrrolidone)‑iodine (PVPI) and polycaprolactone (PCL) were fabricated using a co-axial elect...
Source: Materials Science and Engineering: C - Category: Materials Science Source Type: research
Publication date: May 2020Source: Materials Science and Engineering: C, Volume 110Author(s): Xinxin Chen, Xiang Wang, Siyu Wang, Xiuhang Zhang, Jiaao Yu, Ce WangAbstractThere has been a recent increase in research interest regarding the development of wound dressings containing bioactive compounds capable of improving outcomes for complex healing needs. In the present study, we describe the generation of bromelain immobilized eletrospun poly(ε-caprolactone) (PCL) fibers (BrPDA-PCL fibers) using the dopamine-assisted co-deposition strategy. We wanted to combine the structural advantage of electrospun fiber and the a...
Source: Materials Science and Engineering: C - Category: Materials Science Source Type: research
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Source: Biochimie - Category: Biochemistry Authors: Tags: Biochimie Source Type: research
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Source: Materials Science and Engineering: C - Category: Materials Science Source Type: research
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Source: Cell Reports - Category: Cytology Source Type: research
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