Isolation and Toxigenic Characteristics of a Tetrodotoxin Producing Bacteria

Tetrodotoxin (TTX) is a kind of neurotoxin with great scientific research and medicinal value. Studies have confirmed that microorganism is one of the important sources of TTX. However, the specific biosynthetic and regulatory pathway of TTX production by microorganisms are still unclear. In this paper, out of twelve symbiotic bacteria screened from the wild puffer fish (Fugu rubripes) collected from coastal sea area of Ningbo (Zhejiang, China), a strain named He-1 isolated from the liver of puffer fish was found can produce TTX. It was identified as Bacillus cereus based on physiological, biochemical characteristics and 16S rDNA gene analysis. However, the strain He-2, which is the subculture strain of He-1, cannot produce TTX under the normal culture condition. Further study showed that by adding the metabolite of the He-1, the ability of TTX producing of He-2 could be restored. A peptide compound was obtained by separating and purifying of the metabolites from strain He-1, which could induce the TTX production of strain He-2. This work will provide a new way for further revealing the anabolic pathway of TTX.

A Fatty Acid Anabolic Pathway in Specialized-Cells Remotely Controls Oocyte Activation in Drosophila

ABSTRACTPheromone-mediated partner recognition is crucial for maintenance of animal species. Here, we discover a metabolic link between pheromone and gamete physiology. In female genital tract, oocyte maturation is arrested at a specific meiotic-phase. Release of this arrest, called oocyte-activation, is triggered by a species-dependent signal. We show in Drosophila melanogaster that oenocytes, which produce the fatty acids (FAs) used as precursors of cuticular hydrocarbons (CHCs), including pheromones, are also essential for oocyte activation. We identified a set of FA-anabolic enzymes required within oenocytes for the synthesis of a particular FA that is not a CHC precursor but controls oocyte activation. Our study thus reveals that two tightly linked FA-anabolic pathways act in parallel, one to produce sexual pheromones, the other to initiate embryonic development. Given that pheromone-deficient Drosophila melanogaster females are highly attractive for males irrespective of their species, this oenocyte function might have evolved to prevent hybrid development.

Protein kinase A controls the hexosamine pathway by tuning the feedback inhibition of GFAT-1

The hexosamine pathway (HP) is a key anabolic pathway whose product uridine 5’-diphospho-N-acetyl-D-glucosamine (UDP-GlcNAc) is an essential precursor for glycosylation processes in mammals. It modulates the ER stress response and HP activation extends lifespan in Caenorhabditis elegans. The highly conserved glutamine fructose-6-phosphate amidotransferase 1 (GFAT-1) is the rate-limiting HP enzyme. GFAT-1 activity is modulated by UDP-GlcNAc feedback inhibition and via phosphorylation by protein kinase A (PKA). Molecular consequences of GFAT-1 phosphorylation, however, remain poorly understood. Here, we identify the GFAT-1 R203H substitution that elevates UDP-GlcNAc levels in C. elegans. In human GFAT-1, the R203H substitution interferes with UDP-GlcNAc inhibition and with PKA-mediated Ser205 phosphorylation. Our data indicate that phosphorylation affects the interactions of the two GFAT-1 domains to control catalytic activity. Notably, Ser205 phosphorylation has two discernible effects: it lowers baseline GFAT-1 activity and abolishes UDP-GlcNAc feedback inhibition. PKA controls the HP by uncoupling the metabolic feedback loop of GFAT-1.

Ketogenic Diet-mediated Steroid Metabolism Reprogramming Improves the Immune Microenvironment and Myelin Growth of Spinal Cord Injury Rats Through Gene Analysis and Co-expression Network Analysis

BackgroundThe ketogenic diet has been widely used in the treatment of various nervous system and metabolic-related diseases. Our previous research found that a ketogenic diet exerts a protective effect and promotes functional recovery after spinal cord injury. However, the mechanism of treatment is still unclear. In this study, different dietary feeding methods were used to detect myelin expression and gene level changes between different groups.ResultFirst, KEGG pathway enrichment of upregulated differentially expressed genes (DEGs) in the SCI_KD and SCI_SD groups and GSEA analysis of the two groups found that a ketogenic diet significantly improved the steroid anabolic pathway in rats with spinal cord injury. Through cluster analysis, PPI analysis and visualization of iPath metabolic pathways, Sqle, Sc5d, Cyp51, Dhcr24, Msmo1, Hsd17b7, and Fdft1 changed significantly in the pathway. Second, through WGCNA analysis, all samples are placed in a gene network to analyse the correlation between gene modules and phenotypes. After module analysis, GO function and KEGG analysis showed that rats fed a ketogenic diet showed significantly reduced immune-related pathways, including those associated with immune and infectious diseases.ConclusionA ketogenic diet may improve the immune microenvironment and myelin growth in rats with spinal cord injury through reprogramming of steroid metabolism.

Protein kinase A controls the hexosamine pathway by tuning the feedback inhibition of GFAT-1

The hexosamine pathway (HP) is a key anabolic pathway whose product uridine 5’-diphospho-N-acetyl-D-glucosamine (UDP-GlcNAc) is an essential precursor for all glycosylation processes in mammals. It modulates the ER stress response and HP activation extends lifespan in Caenorhabditis elegans. The highly conserved glutamine fructose-6-phosphate amidotransferase 1 (GFAT-1) is the rate-limiting HP enzyme. GFAT-1 activity is modulated by UDP-GlcNAc feedback inhibition and through phosphorylation by protein kinase A (PKA). Molecular consequences of GFAT-1 phosphorylation, however, remain poorly understood. Here, we identify the GFAT-1 R203H substitution that elevates UDP-GlcNAc levels in C. elegans. In human GFAT-1, the R203H substitution interfered with both UDP-GlcNAc inhibition and with PKA-mediated Ser205 phosphorylation. Our data indicate that phosphorylation affects the relative positioning of the two GFAT-1 domains to control its activity. Of note, Ser205 phosphorylation had two discernible effects: It lowered baseline GFAT-1 activity and abolished UDP-GlcNAc feedback inhibition. Thus, PKA controls the HP by uncoupling the metabolic feedback loop of GFAT-1.

Raffinose synthase enhances drought tolerance through raffinose synthesis or galactinol hydrolysis in maize and Arabidopsis plants

Raffinose and its precursor galactinol accumulate in plant leaves during abiotic stress. RAFFINOSE SYNTHASE (RAFS) catalyzes raffinose formation by transferring a galactosyl group of galactinol to sucrose. However, whether RAFS contributes to plant drought tolerance and, if so, by what mechanism remains unclear. In this study, we report that expression of RAFS from maize (or corn, Zea mays) (ZmRAFS) is induced by drought, heat, cold, and salinity stresses. We found that zmrafs mutant maize plants completely lack raffinose and hyper-accumulate galactinol and are more sensitive to drought stress than the corresponding null-segregant (NS) plants. This indicated that ZmRAFS and its product raffinose contribute to plant drought tolerance. ZmRAFS overexpression in Arabidopsis enhanced drought stress tolerance by increasing myo-inositol levels via ZmRAFS-mediated galactinol hydrolysis in the leaves due to sucrose insufficiency in leaf cells and also enhanced raffinose synthesis in the seeds. Supplementation of sucrose to detached leaves converted ZmRAFS from hydrolyzing galactinol to synthesizing raffinose. Taken together, we demonstrate that ZmRAFS enhances plant drought tolerance through either raffinose synthesis or galactinol hydrolysis, depending on sucrose availability in plant cells. These results provide new avenues to improve plant drought stress tolerance through manipulation of the raffinose anabolic pathway.

COVID-19 Disease: ORF8 and Surface Glycoprotein Inhibit Heme Metabolism by Binding to Porphyrin

<p>The novel coronavirus pneumonia (COVID-19) is an infectious acute respiratory infection caused by the novel coronavirus. The virus is a positive-strand RNA virus with high homology to bat coronavirus. Due to the limits of the existing experimental tools, many protein roles of novel coronavirus including ORF8 are still unclear. Therefore, in the current scene of an emergency epidemic, it is of high scientific significance to predict the biological role of viral proteins through bioinformatics methods. In this study, conserved domain analysis, homology modeling, and molecular docking were used to compare the biological roles of certain proteins of the novel coronavirus. The results showed the ORF8 and surface glycoprotein could bind to the porphyrin, respectively, while orf1ab, ORF10 and ORF3a proteins could coordinately attack heme to dissociate the iron to form the porphyrin. The mechanism seriously interfered with the normal heme anabolic pathway of the human body, being expected to result in human disease. According to the validation analysis of these finds, Chloroquine could prevent orf1ab, ORF3a and ORF10 to attack the heme to form the porphyrin, and inhibit the binding of ORF8 and surface glycoproteins to porphyrins to a certain extent. Therefore, this research is of high value to contemporary biological experiments, disease prevention and clinical treatment.</p>

COVID-19 Disease: ORF8 and Surface Glycoprotein Inhibit Heme Metabolism by Binding to Porphyrin

<p>The novel coronavirus pneumonia (COVID-19) is an infectious acute respiratory infection caused by the novel coronavirus. The virus is a positive-strand RNA virus with high homology to bat coronavirus. Due to the limits of the existing experimental tools, many protein roles of novel coronavirus including ORF8 are still unclear. Therefore, in the current scene of an emergency epidemic, it is of high scientific significance to predict the biological role of viral proteins through bioinformatics methods. In this study, conserved domain analysis, homology modeling, and molecular docking were used to compare the biological roles of certain proteins of the novel coronavirus. The results showed the ORF8 and surface glycoprotein could bind to the porphyrin, respectively, while orf1ab, ORF10 and ORF3a proteins could coordinately attack heme to dissociate the iron to form the porphyrin. The mechanism seriously interfered with the normal heme anabolic pathway of the human body, being expected to result in human disease. According to the validation analysis of these finds, Chloroquine could prevent orf1ab, ORF3a and ORF10 to attack the heme to form the porphyrin, and inhibit the binding of ORF8 and surface glycoproteins to porphyrins to a certain extent. Therefore, this research is of high value to contemporary biological experiments, disease prevention and clinical treatment.</p>

COVID-19 Disease: ORF8 and Surface Glycoprotein Inhibit Heme Metabolism by Binding to Porphyrin

<p>The novel coronavirus pneumonia (COVID-19) is an infectious acute respiratory infection caused by the novel coronavirus. The virus is a positive-strand RNA virus with high homology to bat coronavirus. Due to the limits of the existing experimental tools, many protein roles of novel coronavirus including ORF8 are still unclear. Therefore, in the current scene of an emergency epidemic, it is of high scientific significance to predict the biological role of viral proteins through bioinformatics methods. In this study, conserved domain analysis, homology modeling, and molecular docking were used to compare the biological roles of certain proteins of the novel coronavirus. The results showed the ORF8 and surface glycoprotein could bind to the porphyrin, respectively, while orf1ab, ORF10 and ORF3a proteins could coordinately attack heme to dissociate the iron to form the porphyrin. The mechanism seriously interfered with the normal heme anabolic pathway of the human body, being expected to result in human disease. According to the validation analysis of these finds, Chloroquine could prevent orf1ab, ORF3a and ORF10 to attack the heme to form the porphyrin, and inhibit the binding of ORF8 and surface glycoproteins to porphyrins to a certain extent. Therefore, this research is of high value to contemporary biological experiments, disease prevention and clinical treatment.</p>