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Efflux pumps and membrane permeability contribute to intrinsic antibiotic resistance in Mycobacterium abscessus.

Mycobacterium abscessus is a pulmonary pathogen that exhibits intrinsic resistance to antibiotics, but the factors driving this resistance a … cumulates the least, suggesting that inadequate uptake impacts its efficacy. We utilized transposon mutagenesis screening to identify genes that cause linezolid resistance and found multiple transporters that promote membrane permeability or efflux, including an uncharacterized protein that effluxes linezolid and several chemically related antibiotics. This d …

Neuronal somatic mutations are increased in multiple sclerosis lesions.

Neuroinflammation underpins neurodegeneration and clinical progression in multiple sclerosis (MS), but knowledge of processes linking these disease mechanisms remains incomplete. Here we investigated somatic single-nucleotide variants (sSNVs) in the genomes of 106 single neurons from post-mortem brain tissue of ten MS cases and 16 controls to determine whether somatic mutagenesis is involved. We observed an increase of 43.9 sSNVs per year in neurons from chronic MS lesions, a 2.5 times faster rate than in neurons from normal-appearing MS and control tissues. This difference was equivalent to 1…

Структурное и механистическое профилирование модулятуры Hurr1 vidofludimus позволяет проектировать лиганд на основе структуры.

В центре биомедицинских исследований находится фактор нейрозащиты, связанный с ядерным рецептором 1 (Nurr1, NR4A2) для его многообещающей нейрозащитной роли в болезни Паркинсона, болезни Альцгеймера и множественном склерозе. Его деятельность может контролироваться лигандами, предлагающими доступ к фармакологической модуляции Hurr1. Вместе с тем связующие эпитопы и механизмы молекулярной активации синтетических активаторов Hurr1 по-прежнему остаются труднодостижимыми, но имеют важное значение для продвижения к новым лекарствам лигандов Hurr1. Здесь мы охарактеризовали диссоциацию Hurr1 димера и

Совпадение в аннотации оригинала
The neuroprotective transcription factor nuclear receptor related 1 (Nurr1, NR4A2) is in the focus of biomedical research for its promising … ofludimus and locate its binding in an allosteric surface pocket lined by helices 1, 5, 7, and 8 by mutagenesis and molecular dynamics simulation. Structure-guided ligand design using these insights resulted in an optimized Nurr1 agonist with substantially enhanced potency and binding affinity. Our results provide a structural and molecular basis for Nurr1 ac …

Overactive mitochondrial DNA replication disrupts perinatal cardiac maturation.

High mitochondrial DNA (mtDNA) amount has been reported to be beneficial for resistance and recovery of metabolic stress, while increased mt … thy and cardiac collapse during the first days of life. The pathogenesis, further enhanced by mtDNA mutagenesis, involves prenatal upregulation of mitochondrial integrated stress response and the ferroptosis-inducer MESH1, leading to cardiac fibrosis and cardiomyocyte death after birth. Our evidence indicates that the tight control of mtDNA replication is cri …

Translation initiation factor eIF1.2 promotes Toxoplasma stage conversion by regulating levels of key differentiation factors.

The parasite Toxoplasma gondii persists in its hosts by converting from replicating tachyzoites to latent bradyzoites housed in tissue cysts. The molecular mechanisms that mediate T. gondii differentiation remain poorly understood. Through a mutagenesis screen, we identified translation initiation factor eIF1.2 as a critical factor for T. gondii differentiation. A F97L mutation in eIF1.2 or the genetic ablation of eIF1.2 (∆eif1.2) markedly impeded bradyzoite cyst formation in vitro and in vivo. We demonstrated, at single-molecule level, that the eIF1.2 F97L mutation impacts the scanning proces…

Crystal structure of an antibody specifically recognizing 3,4-methyl enedioxy methamphetamine through the epoxide moiety.

3,4-methylenedioxymethamphetamine (MDMA) or publicly known as "ecstasy" is a drug abuse substance. Since antibodies that detect MDMA typically also recognize its chemical analogue, methamphetamine (METH), we identified antibodies specifically recognizing MDMA, but not METH, named 1bB11 and 1bF12, using phage display. The crystal structure of 1bB11 in complex with MDMA was determined at 3.2 Å resolution. Key interactions were found between the epoxide moiety of MDMA and S34 and Y36 of the light chain. Additional interaction with E33 of the heavy chain contributes to anchoring MDMA. Mutagenesis-…

Structure-function analysis of 2-sulfamoylacetic acid synthase in altemicidin biosynthesis.

Altemicidin and its analogs are valuable sulfonamide antibiotics with valuable antitumor and antibacterial activities. Structures of altemic … substrates and cofactors. The crystal structure of SbzJ in complex with NAD+, along with subsequent mutagenesis studies, provided insights into how SbzJ recognizes the sulfonamide group of the substrate. Notably, His431 and Glu240 were identified as key residues serving as catalytic bases to activate the catalytic Cys273 and a water molecule. These findings p …

N6-methyladenosine modification is not a general trait of viral RNA genomes.

Despite the nuclear localization of the m6A machinery, the genomes of multiple exclusively-cytoplasmic RNA viruses, such as chikungunya (CHIKV) and dengue (DENV), are reported to be extensively m6A-modified. However, these findings are mostly based on m6A-Seq, an antibody-dependent technique with a high rate of false positives. Here, we address the presence of m6A in CHIKV and DENV RNAs. For this, we combine m6A-Seq and the antibody-independent SELECT and nanopore direct RNA sequencing techniques with functional, molecular, and mutagenesis studies. Following this comprehensive analysis, we fin…

Protein semisynthesis underscores the role of a conserved lysine in activation and desensitization of acid-sensing ion channels.

Acid-sensing ion channels (ASICs) are trimeric ion channels that open a cation-conducting pore in response to proton binding. Excessive ASIC activation during prolonged acidosis in conditions such as inflammation and ischemia is linked to pain and stroke. A conserved lysine in the extracellular domain (Lys211 in mASIC1a) is suggested to play a key role in ASIC function. However, the precise contributions are difficult to dissect with conventional mutagenesis, as replacement of Lys211 with naturally occurring amino acids invariably changes multiple physico-chemical parameters. Here, we study th…

Characterization and Mechanism Study of a Novel PL7 Family Exolytic Alginate Lyase from Marine Bacteria Vibrio sp. W13.

Alginate lyase can degrade alginate into oligosaccharides through β-elimination for various biological, biorefinery, and agricultural purpos … ndicate that VwAlg7A cleaves the sugar bond in an exolytic mode. Based on the molecular docking and mutagenesis results, we further confirmed that R98, H169, and Y303 are important catalytic residues.

Structural Basis of Amide-Forming Adenylation Enzyme VinM in Vicenistatin Biosynthesis.

Adenylation enzymes activate amino acid substrates to aminoacyl adenylates and generally transfer this moiety onto the thiol group of the ph … etheine-type cross-linking probe. The VinM-VinL complex structure in combination with site-directed mutagenesis analysis revealed that the interactions with both the phosphopantetheine arm and VinL are critical for the amide-forming activity of VinM.

One-Step Platform for Maduramicin and Salinomycin Detection Based on Bispecific Monoclonal Antibody and Interpretation of Molecular Recognition Mechanism.

Maduramicin (MAD) and salinomycin (SAL) are the widely used poly(ether ionophore) antibiotics to control coccidiosis in animals. Due to their strong cytotoxicity, strict control over their dosage and residue in animal food is necessary. To improve the detection efficiency of the existing single-residue detection methods, a tetraploid tumor hybrid system was constructed using drug mutagenesis, and the bispecific monoclonal antibody (BsMAb) against MAD and SAL was obtained by hybridization-hybridoma technology. By optimizing the optimal working concentration of the tracer and antibody, a multire…

Combined photoredox/engineered P450 enzymatic direct dioxygen-functionalization of arylalkanes to chiral acyloins.

To date, the examples of difunctionalization of alkanes to directly incorporate two functional groups are very limited. In this study, we combined photoorgano redox catalysis and P450 biocatalysts to obtain dioxygen-functionalization of α/β-C-H bonds of arylalkanes in a straightforward manner. The synthesis of enantiomerically chiral acyloins through a one-pot two-step photoredox/P450-catalyzed cascade reaction is described. Two P450 mutants with stereocomplementary bio-oxidation were obtained using mutagenesis technology and were able to asymmetrically hydroxylate ketones to acyloins with exc…

Mechanisms of Attenuation by Genetic Recoding of Viruses.

The development of safe and effective vaccines against viruses is central to disease control. With advancements in DNA synthesis technology, the production of synthetic viral genomes has fueled many research efforts that aim to generate attenuated viruses by introducing synonymous mutations. Elucidation of the mechanisms underlying virus attenuation through synonymous mutagenesis is revealing interesting new biology that can be exploited for vaccine development. Here, we review recent advancements in this field of synthetic virology and focus on the molecular mechanisms of attenuation by genet…

The evolution of hematopoietic cells under cancer therapy.

Chemotherapies may increase mutagenesis of healthy cells and change the selective pressures in tissues, thus influencing their evolution. However, their contributions to the mutation burden and clonal expansions of healthy somatic tissues are not clear. Here, exploiting the mutational footprint of some chemotherapies, we explore their influence on the evolution of hematopoietic cells. Cells of Acute Myeloid Leukemia (AML) secondary to treatment with platinum-based drugs show the mutational footprint of these drugs, indicating that non-malignant blood cells receive chemotherapy mutations. No tr…

A GMMA-CPS-Based Vaccine for Non-Typhoidal Salmonella.

Non-typhoidal Salmonella are a major cause of gastroenteritis worldwide, as well as causing bloodstream infections in sub-Saharan Africa with a high fatality rate. No vaccine is currently available for human use. Current vaccine development strategies are focused on capsular polysaccharides (CPS) present on the surface of non-typhoidal Salmonella. This study aimed to boost the amount of CPS purified from S. Typhimurium for immunization trials. Random mutagenesis with Tn10 transposon increased the production of CPS colanic acid, by 10-fold compared to wildtype. Immunization with colanic acid or…

A human apolipoprotein L with detergent-like activity kills intracellular pathogens.

Activation of cell-autonomous defense by the immune cytokine interferon-γ (IFN-γ) is critical to the control of life-threatening infections in humans. IFN-γ induces the expression of hundreds of host proteins in all nucleated cells and tissues, yet many of these proteins remain uncharacterized. We screened 19,050 human genes by CRISPR-Cas9 mutagenesis and identified IFN-γ-induced apolipoprotein L3 (APOL3) as a potent bactericidal agent protecting multiple non-immune barrier cell types against infection. Canonical apolipoproteins typically solubilize mammalian lipids for extracellular transport…

Allosteric HIV Integrase Inhibitors Promote Formation of Inactive Branched Polymers via Homomeric Carboxy-Terminal Domain Interactions.

The major effect of allosteric HIV integrase (IN) inhibitors (ALLINIs) is observed during virion maturation, where ALLINI treatment interrup … r formation is inhibited by the host factor LEDGF/p75, as well as ex vivo resistance substitutions. Mutagenesis and biophysical analyses reveal that homomeric carboxy-terminal domain interactions are required to achieve the branched-polymer nature of the ALLINI-induced aggregates. These studies provide key insight into the mechanisms of ALLINI action and resi …

The Siderophore Synthetase IucA of the Aerobactin Biosynthetic Pathway Uses an Ordered Mechanism.

Biosynthesis of the hydroxamate siderophore aerobactin requires the activity of four proteins encoded within the iuc operon. Recently, we bi … tion of the quaternary complex. We further probed two regions of the active site with site-directed mutagenesis and identified several residues, including a conserved motif that is present on a dynamic loop, that are important for substrate binding and catalysis.

Two Aldehyde Clearance Systems Are Essential to Prevent Lethal Formaldehyde Accumulation in Mice and Humans.

Reactive aldehydes arise as by-products of metabolism and are normally cleared by multiple families of enzymes. We find that mice lacking tw … me. Endogenous formaldehyde clearance alone is therefore critical for hematopoiesis and in limiting mutagenesis in somatic tissues.