Sequence, structure, and function of the Dps DNA-binding protein from Deinococcus wulumuqiensis R12

Effects of hydrothermal treatment and low pH on the fermentation characteristics of polysaccharides based water-soluble Maitake with Lactobacillus acidophilus and L. plantarum

Maitake (Grifola frondosa) is rich in bioactive polysaccharides and is known for its health benefits. This study investigated the effects of hydrothermal treatment (HT) and low pH conditions on Maitake, revealing their effectiveness in the bioactive polysaccharide extraction and metabolite bioavailability. HT and low pH-induced significant structural changes, with WSP-HT1 showing 99.67 % degradation and yielding 41.46 % β-glucan and 0.43 % α-glucan. Sodium Dodecyl Sulfate-Polyacrylamide Gel Electrophoresis demonstrated 45-10 kDa protein transformations, supported by molecular docking and dynamic simulations. FT-IR spectroscopy revealed carbohydrate spectral shifts and increased α-helix random coil association. Treated samples (WSP-LA-pH1, WSP-LA-pH4, WSP-LP-pH1, WSP-LP-pH4) exhibited enhanced optical density, antioxidant activity, fluorescence, and decried surface hydrophobicity. The metabolomic analysis highlighted significant pathway alterations, validated by Principal Component, Partial Least Squares Discriminant, Variable Importance in Projection, and Kyoto Encyclopedia of Genes and Genomes analysis. These findings confirm that hydrothermal treatment and low pH effectively extract active substances, enriching Maitake's medicinal properties.

Multi-enzyme assemblies both in the cell membrane and cytoplasm boost intracellular lycopene production

The multi-enzyme assembly system demonstrates remarkable potential in enhancing both intracellular and extracellular enzyme catalysis. In this study, we employed a novel icosahedral protein cage, Mi3, as a protein scaffold and combined it with an ester bond-based peptide tagging system, ReverseTag/ReverseCatcher, to improve the enzymatic catalytic efficiency both in vitro and in vivo. In vitro, we fused ReverseTag to the N-terminal of exo-inulinase (EXINU) from Pseudomonas mucidolens, yielding ReverseTag-EXINU, which effectively bound to the surface of the ReverseCatcher-Mi3 protein cage. Following assembly, the Km value decreased from 16.3 to 7.9 g/L, while kcat/Km value increased from 1.9 to 3.0 L s-1 g-1, indicating a significant enhancement in substrate affinity and enzymatic catalytic efficiency. In vivo, we constructed a protein-cage multi-enzyme assembly system located in the cytoplasm and cell membrane based on ReverseTag/ReverseCatcher/Mi3 system. In lycopene biosynthesis, the production of lycopene after assembly was increased by 2.97 times compared to free enzyme catalysis. This strategy holds profound implications for fields such as synthetic biology and enzyme engineering.

Deinococcus wulumuqiensis R12 synthesized silver nanoparticles with peroxidase-like activity for synergistic antibacterial application

The use of a combination of several antibacterial agents for therapy holds great promise in reducing the dosage and side effects of these agents, improving their efficiency, and inducing potential synergistic therapeutic effects. Herein, this study provides an innovative antibacterial treatment strategy by synergistically combining R12-AgNPs with H2O2 therapy. R12-AgNPs were simply produced with the supernatant of an ionizing radiation-tolerant bacterium Deinococcus wulumuqiensis R12 by one-step under room temperature. In comparison with chemically synthesized AgNPs, the biosynthesized AgNPs presented fascinating antibacterial activity and peroxidase-like properties, which endowed it with the capability to catalyze the decomposition of H2O2 to generate hydroxyl radical. After the combination of R12-AgNPs and H2O2, an excellent synergistic bacteriostatic activity was observed for both Escherichia coli and Staphylococcus aureus, especially at low concentrations. In addition, in vitro cytotoxicity tests showed R12-AgNPs had good biocompatibility. Thus, this work presents a novel antibacterial agent that exhibits favorable synergistic antibacterial activity and low toxicity, without the use of antibiotics or a complicated synthesis process.

Exploring DNA Damage and Repair Mechanisms: A Review with Computational Insights

DNA damage is a critical factor contributing to genetic alterations, directly affecting human health, including developing diseases such as cancer and age-related disorders. DNA repair mechanisms play a pivotal role in safeguarding genetic integrity and preventing the onset of these ailments. Over the past decade, substantial progress and pivotal discoveries have been achieved in DNA damage and repair. This comprehensive review paper consolidates research efforts, focusing on DNA repair mechanisms, computational research methods, and associated databases. Our work is a valuable resource for scientists and researchers engaged in computational DNA research, offering the latest insights into DNA-related proteins, diseases, and cutting-edge methodologies. The review addresses key questions, including the major types of DNA damage, common DNA repair mechanisms, the availability of reliable databases for DNA damage and associated diseases, and the predominant computational research methods for enzymes involved in DNA damage and repair.

A novel UV-resistant bacterium Sphingomonas endolithica sp. nov., and genomic analysis, isolated from the north slope of Mount Everest

Gram-stain-negative, aerobic, rod-shaped, non-motile bacterium strain ZFBP2030T was isolated from a rock on the North slope of Mount Everest. This strain contained a unique ubiquinone-10 (Q-10) as a predominant respiratory quinone. Among the tested fatty acids, the strain contained summed feature 8, C14:0 2OH, and C16:0, as major cellular fatty acids. The polar lipid profile contained phosphatidyl glycerol, phosphatidyl ethanolamine, three unidentified phospholipids, two unidentified aminolipids, and six unidentified lipids. The cell-wall peptidoglycan was a meso-diaminopimelic acid, and cell-wall sugars were ribose and galactose. Phylogenetic analyses based on 16S rRNA gene sequence revealed that strain ZFBP2030T was a member of the genus Sphingomonas, exhibiting high sequence similarity to the 16S rRNA gene sequences of Sphingomonas aliaeris DH-S5T (97.9%), Sphingomonas alpina DSM 22537T (97.3%) and Sphingomonas hylomeconis CCTCC AB 2013304T (97.0%). The 16S rRNA gene sequence similarity between ZFBP2030T and other typical strains was less than 97.0%. The average amino acid identity values, average nucleotide identity, and digital DNA-DNA hybridization values between strain ZFBP2030T and its highest sequence similarity strains were 56.9-79.9%, 65.1-82.2%, and 19.3-25.8%, respectively. The whole-genome size of the novel strain ZFBP2030T was 4.1 Mbp, annotated with 3838 protein-coding genes and 54 RNA genes. Moreover, DNA G + C content was 64.7 mol%. Stress-related functions predicted in the subsystem classification of the strain ZFBP2030T genome included osmotic, oxidative, cold/heat shock, detoxification, and periplasmic stress responses. The overall results of this study clearly showed that strain ZFBP2030T is a novel species of the genus Sphingomonas, for which the name Sphingomonas endolithica sp. nov. is proposed. The type of strain is ZFBP2030T (= EE 013T = GDMCC 1.3123T = JCM 35386T).

Dps Functions as a Key Player in Bacterial Iron Homeostasis

Iron plays a vital role in the maintenance of life, being central to various cellular processes, from respiration to gene regulation. It is essential for iron to be stored in a nontoxic and readily available form. DNA binding proteins under starvation (Dps) belong to the ferritin family of iron storage proteins and are adept at storing iron in their hollow protein shells. Existing solely in prokaryotes, these proteins have the additional functions of DNA binding and protection from oxidative stress. Iron storage proteins play a functional role in storage, release, and transfer of iron and therefore are central to the optimal functioning of iron homeostasis. Here we review the multifarious properties of Dps through relevant biochemical and structural studies with a focus on iron storage and ferroxidation. We also examine the role of Dps as a possible candidate as an iron donor to iron-sulfur (Fe-S) clusters, which are ubiquitous to many biological processes.

SLICER: A Seamless Gene Deletion Method for Deinococcus radiodurans

Deinococcus radiodurans' high resistance to various stressors combined with its ability to utilize sustainable carbon sources makes it an attractive bacterial chassis for synthetic biology and industrial bioproduction. However, to fully harness the capabilities of this microbe, further strain engineering and tool development are required. Methods for creating seamless genome modifications are an essential part of the microbial genetic toolkit to enable strain engineering. Here, we report the development of the SLICER method, which can be used to create seamless gene deletions in D. radiodurans. This process involves (a) integration of a seamless deletion cassette replacing a target gene, (b) introduction of the pSLICER plasmid to mediate cassette excision by I-SceI endonuclease cleavage and homologous recombination, and (c) curing of the helper plasmid. We demonstrate the utility of SLICER for creating multiple gene deletions in D. radiodurans by sequentially targeting 5 putative restriction-modification system genes, recycling the same selective and screening markers for each subsequent deletion. While we observed no significant increase in transformation efficiency for most of the knockout strains, we demonstrated SLICER as a promising method to create a fully restriction-minus strain to expand the synthetic biology applications of D. radiodurans, including its potential as an in vivo DNA assembly platform.