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ACS Synthetic Biology Jun 2024l-Valine, an essential amino acid, serves as a valuable compound in various industries. However, engineering strains with both high yield and purity are yet to be...
l-Valine, an essential amino acid, serves as a valuable compound in various industries. However, engineering strains with both high yield and purity are yet to be delivered for microbial l-valine production. We engineered a strain capable of highly efficient production of l-valine. We initially introduced an acetohydroxy acid synthase mutant from an industrial l-valine producer and optimized a cofactor-balanced pathway, followed by the activation of the nonphosphoenolpyruvate-dependent carbohydrate phosphotransferase system and the introduction of an exogenous Entner-Doudoroff pathway. Subsequently, we weakened anaplerotic pathways, and attenuated the tricarboxylic acid cycle via start codon substitution in , encoding isocitrate dehydrogenase. Finally, to balance bacterial growth and l-valine production, an l-valine biosensor-dependent genetic circuit was established to dynamically repress citrate synthase expression. The engineered strain Val19 produced 103 g/L of l-valine with a high yield of 0.35 g/g glucose and a productivity of 2.67 g/L/h. This represents the highest reported l-valine production in via direct fermentation and exhibits potential for its industrial-scale production, leveraging the advantages of over other microbes.
PubMed: 38946081
DOI: 10.1021/acssynbio.4c00278 -
FEBS Letters Jun 2024The human FoxP transcription factors dimerize via three-dimensional domain swapping, a unique feature among the human Fox family, as result of evolutionary sequence...
The human FoxP transcription factors dimerize via three-dimensional domain swapping, a unique feature among the human Fox family, as result of evolutionary sequence adaptations in the forkhead domain. This is the case for the conserved glycine and proline residues in the wing 1 region, which are absent in FoxP proteins but present in most of the Fox family. In this work, we engineered both glycine (G) and proline-glycine (PG) insertion mutants to evaluate the deletion events in FoxP proteins in their dimerization, stability, flexibility, and DNA-binding ability. We show that the PG insertion only increases protein stability, whereas the single glycine insertion decreases the association rate and protein stability and promotes affinity to the DNA ligand.
PubMed: 38946055
DOI: 10.1002/1873-3468.14972 -
FEBS Letters Jun 2024Cyanobacteria move by gliding motility on surfaces toward the light or away from it. It is as yet unclear how the light direction is sensed on the molecular level....
Cyanobacteria move by gliding motility on surfaces toward the light or away from it. It is as yet unclear how the light direction is sensed on the molecular level. Diverse photoreceptor knockout mutants have a stronger response toward the light than the wild type. Either the light direction is sensed by multiple photoreceptors or by photosystems. In a study on photophobotaxis of the filamentous cyanobacterium Phormidium lacuna, broad spectral sensitivity, inhibition by 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU), and a highly sensitive response speaks for photosystems as light direction sensors. Here, it is discussed whether the photosystem theory could hold for phototaxis of other cyanobacteria.
PubMed: 38946046
DOI: 10.1002/1873-3468.14968 -
The Journal of Heredity Jul 2024Mpv17 (mitochondrial inner membrane protein MPV17) deficiency causes severe mitochondrial DNA depletion syndrome in mammals and loss of pigmentation of iridophores and a...
Mpv17 (mitochondrial inner membrane protein MPV17) deficiency causes severe mitochondrial DNA depletion syndrome in mammals and loss of pigmentation of iridophores and a significant decrease of melanophores in zebrafish. The reasons for this are still unclear. In this study, we established an mpv17 homozygous mutant line in Nile tilapia. The developing mutants are transparent due to loss of iridophores and aggregation of pigment granules in the melanophores and disappearance of the vertical pigment bars on the side of the fish. Transcriptome analysis using skin of fish at 30 dpf (days post fertilization) revealed that the genes related to purine (especially pnp4a) and melanin synthesis were significantly downregulated. However, administration of guanine diets failed to rescue the phenotype of the mutants. In addition, no obvious apoptosis signals were observed in the iris of the mutants by TUNEL staining. Significant downregulation of genes related to iridophore differentiation was detected by qPCR. Insufficient ATP, as revealed by ATP assay, α-MSH treatment and adcy5 mutational analysis, might account for the defects of melanophores in mpv17 mutants. Several tissues displayed less mtDNA and decreased ATP levels. Taken together, these results indicated that mutation of mpv17 led to mitochondrial dTMP deficiency, followed by impaired mtDNA content and mitochondrial function, which in turn, led to loss of iridophores and a transparent body color in tilapia.
PubMed: 38946032
DOI: 10.1093/jhered/esae034 -
Physiologia Plantarum 2024Maize (Zea mays L.) is an important food crop with a wide range of uses in both industry and agriculture. Drought stress during its growth cycle can greatly reduce maize...
Maize (Zea mays L.) is an important food crop with a wide range of uses in both industry and agriculture. Drought stress during its growth cycle can greatly reduce maize crop yield and quality. However, the molecular mechanisms underlying maize responses to drought stress remain unclear. In this work, a WRKY transcription factor-encoding gene, ZmWRKY30, from drought-treated maize leaves was screened out and characterized. ZmWRKY30 gene expression was induced by dehydration treatments. The ZmWRKY30 protein localized to the nucleus and displayed transactivation activity in yeast. Compared with wild-type (WT) plants, Arabidopsis lines overexpressing ZmWRKY30 exhibited a significantly enhanced drought stress tolerance, as evidenced by the improved survival rate, increased antioxidant enzyme activity by superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT), elevated proline content, and reduced lipid peroxidation recorded after drought stress treatment. In contrast, the mutator (Mu)-interrupted ZmWRKY30 homozygous mutant (zmwrky30) was more sensitive to drought stress than its null segregant (NS), characterized by the decreased survival rate, reduced antioxidant enzyme activity (SOD, POD, and CAT) and proline content, as well as increased malondialdehyde accumulation. RNA-Seq analysis further revealed that, under drought conditions, the knockout of the ZmWRKY30 gene in maize affected the expression of genes involved in reactive oxygen species (ROS), proline, and myo-inositol metabolism. Meanwhile, the zmwrky30 mutant exhibited significant downregulation of myo-inositol content in leaves under drought stress. Combined, our results suggest that ZmWRKY30 positively regulates maize responses to water scarcity. This work provides potential target genes for the breeding of drought-tolerant maize.
Topics: Zea mays; Reactive Oxygen Species; Droughts; Plant Proteins; Gene Expression Regulation, Plant; Homeostasis; Inositol; Transcription Factors; Arabidopsis; Plants, Genetically Modified; Stress, Physiological; Antioxidants; Plant Leaves; Drought Resistance
PubMed: 38945803
DOI: 10.1111/ppl.14423 -
Clinical Lung Cancer Jun 2024Third-generation epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) have significant antitumor activity to advanced non-small-cell lung cancer...
The Design for a Phase II, Randomized, Multicenter Study of CtDNA-Guided Treatment With Furmonertinib Combined Therapy or Furmonertinib Alone for Untreated Advanced EGFR Mutant Non-small-cell Lung Cancer Patients: The FOCUS-C Study.
BACKGROUND
Third-generation epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) have significant antitumor activity to advanced non-small-cell lung cancer (NSCLC) patients with classic EGFR mutations. However, EGFR-TKI monotherapy shows poor efficacy in patients whose circulating tumor cell DNA (ctDNA) of EGFR mutations cannot be rapidly cleared.
MATERIALS AND METHODS
As a third-generation TKI, furmonertinib has shown superior antitumor activity and minor toxicity. The FOCUS-C study is a prospective, multicenter, randomized controlled trial (NCT05334277) to explore the efficacy and safety of furmonertinib plus pemetrexed-platinum doublet chemotherapy with or without bevacizumab versus furmonertinib monotherapy in untreated advanced EGFR mutant NSCLC patients without EGFR clearance after the induction therapy of furmonertinib. Patients with EGFR clearance will still receive furmonertinib as Arm A. Patients without ctDNA clearance will be randomized in a 2:2:1 ratio as Arm B1 (furmonertinib), Arm B2 (furmonertinib combined with carboplatin and pemetrexed for 4 cycles, and then furmonertinib and pemetrexed as maintenance therapy) and Arm B3 (Arm B2 regimen plus bevacizumab). The primary endpoint is progression-free survival (PFS) in Arm B2/B1. Secondary endpoints include PFS in Arm B3/B1, PFS in Arm A/B1, PFS in Arm B3/B2, objective response and disease control rate, overall survival and safety in all Arms. Exploratory endpoints are focused on the efficacy based on plasma NGS at different timepoints.
CONCLUSION
This study will evaluate the efficacy and tolerability of furmonertinib plus carboplatin and pemetrexed with or without bevacizumab verses furmonertinib alone in untreated patients with advanced EGFR mutant NSCLC without EGFR clearance.
PubMed: 38945800
DOI: 10.1016/j.cllc.2024.06.002 -
Food Research International (Ottawa,... Aug 2024Levilactobacillus brevis is crucial in food fermentation, particularly in sourdough production. However, the cultivation of L. brevis faces a challenge with accumulation...
Levilactobacillus brevis is crucial in food fermentation, particularly in sourdough production. However, the cultivation of L. brevis faces a challenge with accumulation of lactic acid, a major inhibitor. We aimed to increase the acid tolerance of L. brevis, an industrial strain for sourdough fermentation. We used the adaptive laboratory evolution (ALE) to obtain lactic acid tolerant strains. The evolved strain's fermentation and metabolite profiles, alongside sensory evaluation, were compared with the parental strain by using various analytical techniques. The ALE approach increased lactic acid tolerance in the evolved strain showing an increased growth rate by 1.1 and 1.9 times higher than the parental strain at pH 4.1 and 6.5, respectively. Comprehensive analyses demonstrated its potential application in sourdough fermentation, promising reduced downstream costs. The evolved strain, free from genetically modified organisms concerns, has great potential for industrial use by exhibiting enhanced growth in acidic conditions without affecting consumers' bread preferences.
Topics: Fermentation; Bread; Levilactobacillus brevis; Hydrogen-Ion Concentration; Food Microbiology; Lactic Acid; Taste; Humans
PubMed: 38945604
DOI: 10.1016/j.foodres.2024.114584 -
Free Radical Biology & Medicine Jun 2024Innovative solutions for rapid protection against broad-spectrum infections are very important in dealing with complex infection environments. We utilized a functionally...
A Streptococcus pneumoniae endolysin mutant protein ΔA146Ply elicits rapid broad-spectrum mucosal protection in mice via upregulation of GPX4 through TLR4/IRG1/NRF2 to alleviate macrophage ferroptosis.
Innovative solutions for rapid protection against broad-spectrum infections are very important in dealing with complex infection environments. We utilized a functionally inactive mutated endolysin protein of Streptococcus pneumoniae (ΔA146Ply) to immunize mice against pneumonic infections by multidrug-resistant bacteria, Candida albicans and influenza virus type A. ΔA146Ply protection relied on both immunized tissue-resident and monocyte-derived alveolar macrophages and inhibited infection induced ferroptosis that upregulated expression of GPX4 (glutathione peroxidase) in alveolar macrophages. Ferroptosis resistance endowed macrophages with enhanced phagocytosis by inhibiting lipid peroxidation during infection. Moreover, we demonstrated ΔA146Ply upregulated GPX4 through the TLR4/IRG1/NRF2 pathway. ΔA146Ply also induced ferroptosis inhibition and phagocytosis improvement in human monocytes. This mode of action is a novel and potentially prophylactic and rapid broad-spectrum anti-infection mechanism. Our study provides new insights into protective interventions that act by regulating ferroptosis to improve multiple pathogen resistance via GPX4 targeting.
PubMed: 38945457
DOI: 10.1016/j.freeradbiomed.2024.06.025 -
Research in Microbiology Jun 2024Despite being classified as microaerophilic microorganisms, most Campylobacter species can grow anaerobically, using formate or molecular hydrogen (H) as electron...
Despite being classified as microaerophilic microorganisms, most Campylobacter species can grow anaerobically, using formate or molecular hydrogen (H) as electron donors, and various nitrogenous and sulfurous compounds as electron acceptors. Herein, we showed that both L-asparagine (L-Asn) and L-aspartic acid (L-Asp) bolster H-driven anaerobic growth in several Campylobacter species, whereas the D-enantiomer form of both asparagine (D-Asn) and aspartic acid (D-Asp) only increased anaerobic growth in C. concisus strain 13826 and C. ureolyticus strain NCTC10941. A gene annotated as racD encoding for a putative D/L-Asp racemase was identified in the genome of both strains. Disruption of racD in Cc13826 resulted in the inability of the mutant strain to use either D-enantiomer during anaerobic growth. Hence, our results suggest that the racD gene is required for campylobacters to use either D-Asp or D-Asn. The use of D-Asp by various human opportunistic bacterial pathogens, including C. concisus, C. ureolyticus, and also possibly select strains of C. gracilis, C. rectus and C. showae, is significant, because D-Asp is an important signal molecule for both human nervous and neuroendocrine systems. To our knowledge, this is the first report of pathogens scavenging a D-amino acid essential for human health.
PubMed: 38945250
DOI: 10.1016/j.resmic.2024.104219 -
Journal de Mycologie Medicale Jun 2024Pathogenic fungi are a major threat to public health, and fungal infections are becoming increasingly common and treatment resistant. Chitin, a component of the fungal...
BACKGROUND & AIM
Pathogenic fungi are a major threat to public health, and fungal infections are becoming increasingly common and treatment resistant. Chitin, a component of the fungal cell wall, modifies host immunity and contributes to antifungal resistance. Moreover, chitin content is regulated by chitin synthases and chitinases. However, the specific roles and mechanisms remain unclear. In this study, we developed a cytometric imaging assay to quantify chitin content and identify the distribution of chitin in the yeast cell wall.
METHODS
The Candida albicans SC5314 and Nakaseomyces glabratus (ex. C. glabrata) ATCC2001 reference strains, as well as 106 clinical isolates, were used. Chitin content, distribution, and morphological parameters were analysed in 12 yeast species. Moreover, machine learning statistical software was used to evaluate the ability of the cytometric imaging assay to predict yeast species using the values obtained for these parameters.
RESULTS
Our imaging-cytometry assay was repeatable, reproducible, and sensitive to variations in chitin content in C. albicans mutants or after antifungal stimulation. The evaluated parameters classified the yeast species into the correct clade with an accuracy of 85 %.
CONCLUSION
Our findings demonstrate that this easy-to-use assay is an effective tool for the exploration of chitin content in yeast species.
PubMed: 38945044
DOI: 10.1016/j.mycmed.2024.101493