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1.
Phys Rev Lett ; 132(3): 036702, 2024 Jan 19.
Artigo em Inglês | MEDLINE | ID: mdl-38307068

RESUMO

Altermagnetism is a newly identified fundamental class of magnetism with vanishing net magnetization and time-reversal symmetry broken electronic structure. Probing the unusual electronic structure with nonrelativistic spin splitting would be a direct experimental verification of an altermagnetic phase. By combining high-quality film growth and in situ angle-resolved photoemission spectroscopy, we report the electronic structure of an altermagnetic candidate, α-MnTe. Temperature-dependent study reveals the lifting of Kramers degeneracy accompanied by a magnetic phase transition at T_{N}=267 K with spin splitting of up to 370 meV, providing direct spectroscopic evidence for altermagnetism in MnTe.

2.
Nanotechnology ; 35(12)2024 Jan 04.
Artigo em Inglês | MEDLINE | ID: mdl-38064735

RESUMO

Ferromagnetic insulators (FMIs) are intriguing not only due to their rare nature, but also due to their potential applications in spintronics and various electronic devices. One of its key promising applications is based on an FMI-induced magnetic proximity effect, which can impose an effective time-reversal symmetry breaking on the target ultrathin layer to realize novel emergent phenomena. Here, we conduct systematic studies on thin film LaCoO3, an insulator known to be ferromagnet under tensile strain, with varying thicknesses, to establish it as an FMI platform to be integrated in heterostructures. The optimal thickness of the LaCoO3layer, providing a smooth surface and robust ferromagnetism with large remanence, is determined. A heterostructure consisting of an ultrathin target layer (2 uc SrRuO3), the LaCoO3FMI layer, and the La0.5Sr0.5CoO3conducting layer has been fabricated and the angle-resolved photoemission spectroscopy measurement on the multi-layer system demonstrates a sharp Fermi edge and a well-defined Fermi surface without the charging effect. This demonstrates the feasibility of the proposed heterostructure using LaCoO3thin film as the FMI layer, and further lays a groundwork to investigate the magnetic proximity induced phases in quantum materials.

3.
Artigo em Inglês | MEDLINE | ID: mdl-37436803

RESUMO

A Gram-stain-negative, non-motile by gliding and moderately halophilic rod-shaped bacterium HN-2-9-2T was isolated from seawater in Tongyeong, Republic of Korea. The strain grew at concentrations of 0.5‒7 % (w/v) NaCl, at pH 5.5‒8.5 and in a temperature range of 18‒45 °C. HN-2-9-2T shared the highest 16S rRNA gene sequence percentage with Salinimicrobium xinjiangense BH206T (98.2 %). The average nucleotide identity (ANI), average amino acid identity (AAI) and digital DNA-DNA hybridisation (dDDH) values between HN-2-9-2T and the S. xinjiangense BH206T were 76.0 %, 81.9 % and 19.7 %, respectively. The genome comprised 3 509 958 bp with a DNA G+C content of 43.0%. HN-2-9-2T contained MK-6 as the sole menaquinone. The predominant fatty acids were iso-C15 : 0, anteiso-C15 : 0, iso-C17 : 0 3-OH, iso-C16 : 0, iso-C15 : 1G and summed feature 9, comprising iso-C17 : 1ω6c/C16 : 1 10-methyl. The polar lipids contained phosphatidylethanolamine, one unidentified phospholipid, two unidentified aminolipids, an unidentified glycolipid and six unidentified lipids. The polyphasic taxonomic properties indicate that the strain represents a novel species within the genus Salinimicrobium, for which the name Salinimicrobium tongyeongense sp. nov. is proposed. The type strain is HN-2-9-2T (=KCTC 82934T=NBRC 115920T).


Assuntos
Ácidos Graxos , Água do Mar , Ácidos Graxos/química , RNA Ribossômico 16S/genética , Composição de Bases , Filogenia , Técnicas de Tipagem Bacteriana , DNA Bacteriano/genética , Análise de Sequência de DNA , Água do Mar/microbiologia , Vitamina K 2/química
4.
Antonie Van Leeuwenhoek ; 116(8): 791-799, 2023 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-37227603

RESUMO

The taxonomic position of strain EF45031T, isolated from the Neungam Carbonate hot spring, was examined using the polyphasic taxonomic approach. Strain EF45031T shared the highest percentage of 16S rRNA gene sequence with Brachybacterium nesterenkovii CIP 104813 T (97.7%). The average nucleotide identity (ANI), average amino acid identity (AAI), and digital DNA-DNA hybridization (dDDH) values between strain EF45031T and the type strains B. nesterenkovii CIP 104813 T and B. phenoliresistens Phenol-AT were 77.0%, 69.15%, 21.9% and 75.73%, 68.81%, 20.5%, respectively. Phylogenomic analysis using an up-to-date bacterial core gene (UBCG) set revealed that strain EF45031T belonged to the genus Brachybacterium. Growth occurred between 25 and 50 ℃ at pH 6.0-9.0 and could tolerate salinity up to 5% (w/v). Strain had anteiso-C15:0 and anteiso-C17:0 as major fatty acids. Menaquinone-7 (MK-7) was the predominant respiratory menaquinone. The polar lipids were diphosphatidylglycerol, phosphatidylglycerol, three aminolipids, and two unidentified glycolipids. The cell-wall peptidoglycan contained meso-diaminopimelic acid as a diagnostic diamino acid. The genome comprised 2,663,796 bp, with a G + C content of 70.9%. Stress-responsive periplasmic chaperone/protease coding genes were identified in the genome of EF45031T and were not detected in other Brachybacterium species. The polyphasic taxonomic properties indicate that the strain represents a novel species within the genus Brachybacterium, for which the name Brachybacterium sillae sp. nov. is proposed. The type strain is EF45031T (= KCTC 49702 T = NBRC 115869 T).


Assuntos
Actinomycetales , Fontes Termais , Fosfolipídeos/química , RNA Ribossômico 16S/genética , Ácidos Graxos/química , Filogenia , Vitamina K 2/química , DNA , DNA Bacteriano/genética , Análise de Sequência de DNA , Técnicas de Tipagem Bacteriana
5.
Nat Mater ; 20(2): 188-193, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33462465

RESUMO

Spin excitations of magnetic thin films are the founding element for magnetic devices in general. While spin dynamics have been extensively studied in bulk materials, the behaviour in mesoscopic films is less known due to experimental limitations. Here, we employ resonant inelastic X-ray scattering to investigate the spectrum of spin excitations in mesoscopic Fe films, from bulk-like films down to three unit cells. In bulk samples, we find isotropic, dispersive ferromagnons consistent with previous neutron scattering results for bulk single crystals. As the thickness is reduced, these ferromagnetic spin excitations renormalize to lower energies along the out-of-plane direction while retaining their dispersion in the in-plane direction. This thickness dependence is captured by simple Heisenberg model calculations accounting for the confinement in the out-of-plane direction through the loss of Fe bonds. Our findings highlight the effects of mesoscopic scaling on spin dynamics and identify thickness as a knob for fine tuning and controlling magnetic properties.

6.
Arch Microbiol ; 205(1): 23, 2022 Dec 13.
Artigo em Inglês | MEDLINE | ID: mdl-36509934

RESUMO

The Gram-positive, nonmotile, rod-shaped bacterium EF45044T was isolated from a hot spring in Chungju, South Korea. The strain was able to grow at concentrations of 0‒5% (w/v) NaCl, at pH 6.0‒10.0 and in the temperature range of 18‒50 °C. Strain EF45044T showed the highest 16S rRNA gene sequence similarity (98.2%) with Microbacterium ketosireducens DSM 12510T, and the digital DNA‒DNA hybridization (dDDH), average amino acid identity (AAI), and average nucleotide identity (ANI) values were all lower than the accepted species threshold. Strain EF45044T contained MK‒12 and MK‒13 as the predominant respiratory quinones and anteiso‒C17:0, anteiso‒C15:0, and iso‒C16:0 as the major fatty acids. Diphosphatidylglycerol, phosphatidylglycerol, and glycolipid were detected as the major polar lipids. The cell-wall peptidoglycan contained ornithine. The DNA G + C content was 71.4 mol%. Based on the polyphasic data, strain EF45044T (= KCTC 49703T) presents a novel species of the genus Microbacterium, for which the name Microbacterium neungamense sp. nov. is proposed.


Assuntos
Ácidos Graxos , Microbacterium , RNA Ribossômico 16S/genética , Microbacterium/genética , Filogenia , Técnicas de Tipagem Bacteriana , DNA Bacteriano/genética , Análise de Sequência de DNA , Ácidos Graxos/análise , Hibridização de Ácido Nucleico , Fosfolipídeos/química
7.
Biotechnol Bioeng ; 118(11): 4360-4374, 2021 11.
Artigo em Inglês | MEDLINE | ID: mdl-34309016

RESUMO

Excavating the molecular details of many diverse enzymes from metagenomes remains challenging in agriculture, food, health, and environmental fields. We present a versatile method that accelerates metabolic enzyme discovery for highly selective gene capture in metagenomes using next-generation sequencing. Culture-independent enzyme mining of environmental DNA is based on a set of short identifying degenerate sequences specific for a wide range of enzyme superfamilies, followed by multiplexed DNA barcode sequencing. A strategy of 'focused identification of next-generation sequencing-based definitive enzyme research' enabled us to generate targeted enzyme datasets from metagenomes, resulting in minimal hands-on obtention of high-throughput biological diversity and potential function profiles, without being time-consuming. This method also provided a targeted inventory of predicted proteins and molecular features of metabolic activities from several metagenomic samples. We suggest that the efficiency and sensitivity of this method will accelerate the decryption of microbial diversity and the signature of proteins and their metabolism from environmental samples.


Assuntos
Código de Barras de DNA Taxonômico , Enzimas/genética , Sequenciamento de Nucleotídeos em Larga Escala , Metagenômica
8.
Sensors (Basel) ; 20(2)2020 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-31936851

RESUMO

Keeping IoT devices secure has been a major challenge recently. One of the possible solutions to secure IoT devices is to use a physically unclonable function (PUF). A PUF is a security primitive that can generate device-specific cryptographic information by extracting the features of hardware uncertainty. Because PUF instances are very difficult to replicate even by the manufacturer, the generated bit sequence can be used as cryptographic keys or as a unique identifier for the device. Regarding the implementation of PUF, the majority of PUFs introduced over the past decade are in the form of active components and have been implemented as separate chips or embedded as a part of a chip, making it difficult to use them in low-cost IoT devices due to cost and design flexibility. One approach to easily adopt PUFs in resource-constrained IoT devices is to use passive components such as resistors and capacitors (RC) that can be configured at low cost. The main feature of this RC-based PUF is that it extracts the small difference caused by charging and discharging of RC circuits and uses it as a response. In this paper, we extend the previous research and show the possibility to secure IoT devices by using the RC-based PUF.

9.
Sensors (Basel) ; 20(18)2020 Sep 11.
Artigo em Inglês | MEDLINE | ID: mdl-32932851

RESUMO

The ability to estimate the current locations of mobile robots that move in a limited workspace and perform tasks is fundamental in robotic services. However, even if the robot is given a map of the workspace, it is not easy to quickly and accurately determine its own location by relying only on dead reckoning. In this paper, a new signal fluctuation matrix and a tracking algorithm that combines the extended Viterbi algorithm and odometer information are proposed to improve the accuracy of robot location tracking. In addition, to collect high-quality learning data, we introduce a fusion method called simultaneous localization and mapping and Wi-Fi fingerprinting techniques. The results of the experiments conducted in an office environment confirm that the proposed methods provide accurate and efficient tracking results. We hope that the proposed methods will also be applied to different fields, such as the Internet of Things, to support real-life activities.

10.
Molecules ; 25(12)2020 Jun 22.
Artigo em Inglês | MEDLINE | ID: mdl-32580297

RESUMO

Kirsten rat sarcoma viral oncogene homolog (KRAS)-driven colorectal cancer (CRC) is notorious to target with drugs and has shown ineffective treatment response. The seeds of Pharbitis nil, also known as morning glory, have been used as traditional medicine in East Asia. We focused on whether Pharbitis nil seeds have a suppressive effect on mutated KRAS-driven CRC as well as reserving muscle cell functions during CRC progression. Seeds of Pharbitis nil (Pharbitis semen) were separated by chromatography and the active compound of Pharbitis semen (PN) was purified by HPLC. The compound PN efficiently suppressed the proliferation of mutated KRAS-driven CRC cells and their clonogenic potentials in a concentration-dependent manner. It also induced apoptosis of SW480 human colon cancer cells and cell cycle arrest at the G2/M phase. The CRC related pathways, including RAS/ERK and AKT/mTOR, were assessed and PN reduced the phosphorylation of AKT and mTOR. Furthermore, PN preserved muscle cell proliferation and myotube formation in cancer conditioned media. In summary, PN significantly suppressed mutated KRAS-driven cell growth and reserved muscle cell function. Based on the current study, PN could be considered as a promising starting point for the development of a nature-derived drug against KRAS-mutated CRC progression.


Assuntos
Proliferação de Células/efeitos dos fármacos , Neoplasias Colorretais/tratamento farmacológico , Ipomoea nil/química , Proteínas Proto-Oncogênicas p21(ras)/genética , Apoptose/efeitos dos fármacos , Linhagem Celular Tumoral , Cromatografia Líquida de Alta Pressão , Neoplasias Colorretais/genética , Neoplasias Colorretais/patologia , Humanos , Células Musculares/efeitos dos fármacos , Células Musculares/patologia , Mutação/efeitos dos fármacos , Sementes/química
11.
Phys Rev Lett ; 123(11): 117201, 2019 Sep 13.
Artigo em Inglês | MEDLINE | ID: mdl-31573260

RESUMO

Through a combination of experimental measurements and theoretical modeling, we describe a strongly orbital-polarized insulating ground state in an (LaTiO_{3})_{2}/(LaCoO_{3})_{2} oxide heterostructure. X-ray absorption spectra and ab initio calculations show that an electron is transferred from the titanate to the cobaltate layers. The charge transfer, accompanied by a large octahedral distortion, induces a substantial orbital polarization in the cobaltate layer of a size unattainable via epitaxial strain alone. The asymmetry between in-plane and out-of-plane orbital occupancies in the high-spin cobaltate layer is predicted by theory and observed through x-ray linear dichroism experiments. Manipulating orbital configurations using interfacial coupling within heterostructures promises exciting ground-state engineering for realizing new emergent electronic phases in metal oxide superlattices.

12.
Int J Syst Evol Microbiol ; 68(1): 416-422, 2018 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-29227219

RESUMO

A novel extremely halophilic archaeon, designated SAH-A6T, was isolated from a sample of commercial rock salt in Ethiopia. Cells of SAH-A6T were aerobic and pleomorphic. The strain was able to grow at concentrations of 15-30 % (w/v) NaCl (optimum 20-25 % NaCl), at pH 6.0-9.0 (optimum pH 7.0) and in a temperature range of 30-55 °C (optimum 37-45 °C). Mg2+ was not required for growth of SAH-A6T cells. On the basis of 16S rRNA gene sequence analysis, strain SAH-A6T was closely related to Halorubrum halodurans Cb34T (99.1 %), Halorubrum rubrum YC87T (98.9 %), Halorubrum aquaticum EN-2T (98.7 %), Halorubrum cibi JCM 15757T (98.4 %), Halorubrum luteum CGSA15T (97.3 %), Halorubrum lipolyticum 9-3T (97.1 %), Halorubrum tibetense 8W8T (97.1 %), Halorubrum kocurii JCM 1478T (97.1 %), Halorubrum halophilum B8T (97.0 %) and Halorubrum persicum C49T (97.0 %). Phylogenetic analysis based on the rpoB' gene sequences showed that strain SAH-A6T was closely related to Hrr. halodurans Cb34T (99.7 %), Hrr. aquaticum JCM 14031T (99.3 %) and other members of the genus Halorubrum (<99.0 %). The DNA G+C content of the strain was 68.0 mol%. DNA-DNA hybridization between strain SAH-A6T and the most closely related members of the genus Halorubrum were below 55 %, suggesting that the new isolate constitutes a different genospecies. On the bases of chemotaxonomic, phenotypic and genotypic data, strain SAH-A6T (=KCCM 43215T=JCM 31519T) represents a novel species of the genus Halorubrum, for which the name Halorubrumaethiopicum sp. nov. is proposed.


Assuntos
Halorubrum/classificação , Filogenia , Cloreto de Sódio , Composição de Bases , DNA Arqueal/genética , Etiópia , Halorubrum/genética , Halorubrum/isolamento & purificação , Hibridização de Ácido Nucleico , RNA Ribossômico 16S/genética , Análise de Sequência de DNA
13.
Implant Dent ; 27(3): 324-331, 2018 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-29613862

RESUMO

PURPOSE: The aim of this animal study is to evaluate, by histomorphometric analysis, new bone formation in rabbit maxillary sinuses with Bio-Oss and demineralized particulate human tooth graft. MATERIALS AND METHODS: Bilateral sinus augmentation procedures were performed in 8 adult male rabbits. After preparation of replaceable bony windows on the lateral wall of the nasal cavity with a piezoelectric surgical device, deproteinized bovine graft (Bio-Oss) was grafted in the new compartment of the maxillary sinus after elevation of the sinus membrane in the control group. In the experimental group, the demineralized human particulate tooth bone was grafted in the sinus. The replaceable bony window was repositioned over the bone graft in both groups. Animals were killed at 2 and 8 weeks after the surgical procedure. The augmented sinuses were evaluated by histomorphometric analysis using hematoxylin-eosin and Masson trichrome stains. RESULTS: Histologically, new bone was revealed along the elevated sinus membrane and both bone grafts. In the control group, the new bone area at 8 weeks was not significantly different than that at 2 weeks. In the experimental group, the new bone area at 8 weeks was significantly greater than that at 2 weeks. CONCLUSION: Significant higher new bone formation was revealed in the experimental group than in the control group.


Assuntos
Matriz Óssea/transplante , Substitutos Ósseos/farmacologia , Minerais/farmacologia , Levantamento do Assoalho do Seio Maxilar/métodos , Animais , Bovinos , Humanos , Masculino , Osteogênese , Piezocirurgia , Coelhos
14.
Appl Environ Microbiol ; 83(10)2017 05 15.
Artigo em Inglês | MEDLINE | ID: mdl-28258150

RESUMO

There is currently little information on nonphosphorylated sugar epimerases, which are of potential interest for producing rare sugars. We found a gene (the TM0416 gene) encoding a putative d-tagatose-3-epimerase-related protein from the hyperthermophilic bacterium Thermotoga maritima We overexpressed the TM0416 gene in Escherichia coli and purified the resulting recombinant protein for detailed characterization. Amino acid sequence alignment and a structural similarity search revealed that TM0416 is a putative nonphosphorylated sugar epimerase. The recombinant enzyme exhibited maximal C-3 epimerization of l-ribulose to l-xylulose at ∼80°C and pH 7 in the presence of 1 mM Mn2+ In addition, this enzyme showed unusually high activity for the epimerization of d-tagatose to d-sorbose, with a conversion yield of 20% after 6 h at 80°C. Remarkably, the enzyme catalyzed the isomerization of d-erythrose or d-threose to d-erythrulose significantly, with conversion yields of 71% and 54.5%, respectively, after 6 h at 80°C at pH 7. To further investigate the substrate specificity of TM0416, we determined its crystal structures in complex with divalent metal ions and l-erythrulose at resolutions of 1.5 and 1.6 Å. Detailed inspection of the structural features and biochemical data clearly demonstrated that this metalloenzyme, with a freely accessible substrate-binding site and neighboring hydrophobic residues, exhibits different and promiscuous substrate preferences, compared with its mesophilic counterparts. Therefore, this study suggests that TM0416 can be functionally classified as a novel type of l-ribulose 3-epimerase (R3E) with d-erythrose isomerase activity.IMPORTANCE Rare sugars, which occur naturally in small amounts, have attracted considerable attention in the food and drug industries. However, there is little information on nonphosphorylated sugar epimerases, which might potentially be applied for the production of rare sugars. This study describes the characterization and functional annotation of a putative nonphosphorylated sugar 3-epimerase from a hyperthermophilic bacterium. Furthermore, we determined its crystal structures in complex with divalent metal ions and l-erythrulose, highlighting its metal-dependent, bifunctional, sugar-isomerizing activity. This hyperthermophilic R3E exhibited d-erythrose/d-threose isomerase activity, with structural features near the substrate-binding site distinct from those of its mesophilic counterparts. Moreover, this metalloenzyme showed unusually high activity for the epimerization of d-tagatose to d-sorbose at 70°C. Therefore, TM0416 can be functionally classified as a novel type of promiscuous R3E with a potential for the production of rare sugars for the food and pharmaceutical industries.


Assuntos
Proteínas de Bactérias/química , Proteínas de Bactérias/metabolismo , Carboidratos Epimerases/química , Hexoses/metabolismo , Thermotoga maritima/enzimologia , Sequência de Aminoácidos , Proteínas de Bactérias/genética , Carboidratos Epimerases/genética , Carboidratos Epimerases/metabolismo , Catálise , Domínio Catalítico , Cristalografia por Raios X , Estabilidade Enzimática , Dados de Sequência Molecular , Alinhamento de Sequência , Especificidade por Substrato , Thermotoga maritima/química , Thermotoga maritima/genética , Thermotoga maritima/metabolismo
15.
Int J Mol Sci ; 18(8)2017 Aug 11.
Artigo em Inglês | MEDLINE | ID: mdl-28800074

RESUMO

Colon cancer is one of the most common types of cancer, and it has recently become a leading cause of death worldwide. Among colon cancers, the v-ki-ras2 Kirsten rat sarcoma viral oncogene homolog (KRAS)-mutated form is notorious for its non-druggable features. Cetuximab, a monoclonal antibody that binds to the epidermal growth factor receptor, has been introduced as an antitumor therapy; however, secondary resistance and side effects significantly limit its effective use in these cancers. In this study, we prepared Phellinuslinteus on germinated brown rice (PBR) extracts to increase the sensitivity of KRAS-mutated colon cancers to cetuximab. The combined treatment of PBR extract and cetuximab suppressed SW480 cell viability/proliferation, with the cells exhibiting altered cellular morphology and clonogenic potential. AnnexinV-fluorescein isothiocyanate/propidium iodide-stained flow cytometry and Western blotting were performed, and PBR extract combined with cetuximab treatment increased apoptosis of the SW480 cells and suppressed their KRAS protein expression. The potential of PBR as a synergistic anticancer agent was further investigated in a tumor-xenografted mouse model. Tumor growth was significantly suppressed with PBR extract and cetuximab co-treatment. In conclusion, PBR increased the sensitivity of KRAS-mutated colon cancer cells to cetuximab, which indicates the potential use of PBR as a medical food against colon cancer.


Assuntos
Antineoplásicos/uso terapêutico , Basidiomycota/química , Produtos Biológicos/uso terapêutico , Extratos Celulares/uso terapêutico , Cetuximab/uso terapêutico , Neoplasias do Colo/tratamento farmacológico , Animais , Antineoplásicos/administração & dosagem , Antineoplásicos/farmacologia , Apoptose/efeitos dos fármacos , Basidiomycota/patogenicidade , Produtos Biológicos/administração & dosagem , Produtos Biológicos/farmacologia , Extratos Celulares/administração & dosagem , Extratos Celulares/farmacologia , Proliferação de Células/efeitos dos fármacos , Cetuximab/administração & dosagem , Cetuximab/farmacologia , Neoplasias do Colo/genética , Resistencia a Medicamentos Antineoplásicos , Sinergismo Farmacológico , Células HT29 , Humanos , Masculino , Camundongos , Camundongos Nus , Oryza/microbiologia , Proteínas Proto-Oncogênicas p21(ras)/genética
16.
Arch Biochem Biophys ; 596: 51-62, 2016 04 15.
Artigo em Inglês | MEDLINE | ID: mdl-26946941

RESUMO

Thermophilic l-arabinose isomerase (AI), which catalyzes the interconversion of l-arabinose and l-ribulose, can be used to produce d-tagatose, a sugar substitute, from d-galactose. Unlike mesophilic AIs, thermophilic AIs are highly dependent on divalent metal ions for their catalytic activity and thermostability at elevated temperatures. However, the molecular basis underlying the substrate preferences and metal requirements of multimeric AIs remains unclear. Here we report the first crystal structure of the apo and holo forms of thermophilic Geobacillus kaustophilus AI (GKAI) in hexamer form. The structures, including those of GKAI in complex with l-arabitol, and biochemical analyses revealed not only how the substrate-binding site of GKAI is formed through displacement of residues at the intersubunit interface when it is bound to Mn(2+), but also revealed the water-mediated H-bonding networks that contribute to the structural integrity of GKAI during catalysis. These observations suggest metal-mediated isomerization reactions brought about by intersubunit interactions at elevated temperatures are responsible for the distinct active site features that promote the substrate specificity and thermostability of thermophilic AIs.


Assuntos
Aldose-Cetose Isomerases/química , Proteínas de Bactérias/química , Geobacillus/enzimologia , Temperatura Alta , Manganês/química , Cristalografia por Raios X , Estabilidade Enzimática , Ligação de Hidrogênio , Estrutura Quaternária de Proteína
17.
Arch Biochem Biophys ; 585: 39-51, 2015 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-26344854

RESUMO

UDP-galactose 4-epimerase (GalE) catalyzes the interconversion of UDP-glucose (UDP-Glc) and UDP-galactose (UDP-Gal), which is a pivotal step in the Leloir pathway for d-galactose metabolism. Although GalE is widely distributed in prokaryotes and eukaryotes, little information is available regarding hyperthermophilic GalE. We overexpressed the TM0509 gene, encoding a putative GalE from Thermotoga maritima (TMGalE), in Escherichia coli and characterized the encoded protein. To further investigate the molecular basis of this enzyme's catalytic function, we determined the crystal structures of TMGalE and TMGalE bound to UDP-Glc at resolutions of 1.9 Å and 2.0 Å, respectively. The enzyme was determined to be a homodimer with a molecular mass of 70 kDa. The enzyme could reversibly catalyze the epimerization of UDP-GalNAc/UDP-GlcNAc as well as UDP-Gal/UDP-Glc at elevated temperatures, with an apparent optimal temperature and pH of 80 °C and 7.0, respectively. Our data showed that TM0509 is a UDP-galactosugar 4-epimerase involved in d-galactose metabolism; consequently, this study provides the first detailed characterization of a hyperthermophilic GalE. Moreover, the promiscuous substrate specificity of TMGalE, which is more similar to human GalE than E. coli GalE, supports the notion that TMGalE might exhibit the earliest form of sugar-epimerizing enzymes in the evolution of galactose metabolism.


Assuntos
Proteínas de Bactérias/química , Thermotoga maritima/química , UDPglucose 4-Epimerase/química , Uridina Difosfato Galactose/química , Uridina Difosfato Glucose/química , Sequência de Aminoácidos , Proteínas de Bactérias/antagonistas & inibidores , Proteínas de Bactérias/genética , Evolução Biológica , Domínio Catalítico , Cristalografia por Raios X , Escherichia coli/genética , Escherichia coli/metabolismo , Expressão Gênica , Temperatura Alta , Cinética , Modelos Moleculares , Dados de Sequência Molecular , Filogenia , Multimerização Proteica , Estrutura Secundária de Proteína , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Alinhamento de Sequência , Especificidade por Substrato , Thermotoga maritima/classificação , Thermotoga maritima/enzimologia , UDPglucose 4-Epimerase/antagonistas & inibidores , UDPglucose 4-Epimerase/genética
18.
Microbiol Resour Announc ; 13(9): e0057324, 2024 Sep 10.
Artigo em Inglês | MEDLINE | ID: mdl-39162442

RESUMO

We report the complete genomes of Geobacillus stearothermophilus strains EF60045 and SJEF4-2 from Korean hot springs, with 3,769 and 3,625 thermophilic genes, respectively. G. stearothermophilus EF60045 shows four methylation patterns. G. stearothermophilus SJEF4-2 harbors three plasmids. These findings enhance understanding of Geobacillus strains, aiding in their development as microbial platform hosts.

19.
Heliyon ; 9(11): e21213, 2023 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-37954256

RESUMO

To guarantee the right to move for residents in areas where public transportation is insufficient, research is needed to identify vulnerable areas and prepare measures. This paper defines the vulnerable regions of public transportation within various city types in Korea. In order to identify appropriate areas to apply the Demand Responsive Transit (DRT), the regions with vulnerability were compared with a specific city (Yangsan-si) which already the DRT system was successfully adopted. To collect monthly bus data, web-data crawling method was performed and processed with coordinating program by matching GPS coordinate. The public transportation demand was predicted for each grid cell size (100 m, 250 m, and 500 m) by different methodologies. Various data mining models based on regression were analyzed to predict bus demand of vulnerable areas. Among models, a modified model was suggested to combine Automated machine learning models for high prediction performance. The modified model outperformed other methods as 0.685 and prediction performance was appropriate at 100 m rectangle grid. Regional characters of DRT bus allocation areas were extracted by K-means clustering method and differentiate urban and suburban types. The findings of this study provide valuable insights into conditions that DRT bus stop can be installed. The urban bus stop areas located in metropolitan cities and the suburban bus stop allocation areas located in countryside. The study results can be used as policy data for the successful introduction to prevent social exclusion and improve resident welfare in the future.

20.
Nutrients ; 15(2)2023 Jan 07.
Artigo em Inglês | MEDLINE | ID: mdl-36678181

RESUMO

Microbial fermentation provides a valorization strategy, through biotransformation, to convert plant-derived raw materials into health-promoting agents. In this study, we have investigated the antioxidative activity of Abelmoschus manihot fermented with various Bacillaceae strains from specific environments and demonstrated the anti-inflammatory effects of Bacillus licheniformis CP6 fermented A. manihot extract (FAME) in lipopolysaccharide (LPS)-stimulated Raw264.7 macrophages. Of 1500 bacteria isolated from various specific environments, 47 extracellular protease- and amylase-producing strains with qualified presumption safety status, belonging to the family Bacillaceae, were selected for A. manihot fermentation. Among them, strain CP6, a halophilic bacterium isolated from Tongyeong seawater in Korea and identified as B. licheniformis, showed the highest antioxidant activity. In particular, FAME exerted anti-inflammatory effects on LPS-stimulated Raw264.7 macrophages. Consequently, FAME had a potent inhibitory effect on nitric oxide (NO) production in LPS-stimulated macrophages, without cytotoxicity. Moreover, FAME downregulated LPS-induced pro-inflammatory mediator and enzyme levels in LPS-induced Raw264.7 cells, including IL-1ß, IL-6, TNF-α, iNOS, and COX-2, compared to levels when cells were incubated in A. manihot extract (IAME). Further detailed characterization indicated that FAME suppresses inflammation by blocking NF-κB via IKK phosphorylation inhibition and IκB-α degradation and by downregulating NO production, and inflammatory mediators also decreased NF-κB translocation. Furthermore, FAME inhibited LPS-stimulated activation of MAPKs, including ERK1/2, JNK, and p38, compared to that with either IAME. Therefore, we suggest that FAME could be used for inflammation-related disorders.


Assuntos
Abelmoschus , Bacillus licheniformis , NF-kappa B/metabolismo , Transdução de Sinais , Bacillus licheniformis/metabolismo , Lipopolissacarídeos/farmacologia , Fermentação , Anti-Inflamatórios/farmacologia , Inflamação , Extratos Vegetais/farmacologia , Óxido Nítrico/metabolismo , Óxido Nítrico Sintase Tipo II/metabolismo
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