Search Results (7)

Plants adapt to phosphate starvation by remodeling root architecture and reallocating carbohydrates. Glucose-6-phosphate 1-epimerase (G6PE), a key enzyme in carbon and energy metabolism, is hypothesized to contribute to phosphate starvation responses. Here, we investigated the role of G6PE in rice and Arabidopsis through phenotypic, physiological, and molecular analyses of osg6pe and atg6pe mutants. Under normal-phosphate (NP) conditions, both mutants exhibited significantly reduced biomass and fresh weight compared with the wild-type (WT) plants, indicating growth inhibition caused by the mutations. Under low-phosphate (LP) conditions, the mutants displayed enhanced root growth, suggesting that G6PE functions as a negative regulator of radial root growth under phosphate deficiency. The osg6pe mutant showed elevated phosphate content and increased leaf starch accumulation under LP, whereas it accumulated more phosphate but less starch under NP. Expression analysis revealed that G6PE transcripts were suppressed under NP but remained relatively stable under LP. Notably, among phosphate starvation-induced (PSI) genes, only PHT1;4 showed notable transcriptional changes in both species. These findings indicate that G6PE contributes to phosphate homeostasis by modulating carbohydrate metabolism, restraining radial root growth, and selectively regulating PHT1 expression under phosphate-deficient conditions. Full article

Erythritol has been widely used in the food industry, which predominantly synthesizes it via microbial fermentation, in which Yarrowia lipolytica serves as the preferred candidate chassis strain. However, the wild-type strain of Y. lipolytica exhibits several limitations, including suboptimal industrial performance and elevated levels of by-products, which pose significant challenges in biomanufacturing processes. It is significant to understand the synthesis mechanism of erythritol for improving the capacity of erythritol production by Y. lipolytica. In this study, a mutant exhibiting high erythritol production and stable genetic performance was obtained via a combination of UV and atmospheric and room-temperature plasma mutagenesis. Some key genes related to erythritol production were identified through comparative transcriptome analysis of the mutant strain, revealing significant changes in their expression levels. Individual overexpression of the genes encoding ribose-5-phosphate isomerase, glucose-6-phosphate-1-epimerase, adenylate kinase, and alcohol dehydrogenase in Y. lipolytica Po1g enhanced erythritol production, demonstrating the critical role of each gene in erythritol production. This finding elucidates the molecular mechanism underlying the improved erythritol yield in the mutant strain. The Y. lipolytica mutant C1 produced 194.47 g/L erythritol in a 10 L fermenter with a productivity of 1.68 g/L/h during batch fermentation, surpassing the wild-type strain and reducing the cultivation time by 21 h. It is significant to understand the mechanism of erythritol synthesis for improving erythritol production and its application in industrial-scale production. Full article

This study aimed to provide an inclusive in silico investigation for the identification of novel drug targets that can be exploited to develop drug candidates for treating oral infections caused by S. sputigena. By coupling subtractive genomics with an in silico drug discovery approach, we identified dTDP-4-dehydrorhamnose 3,5-epimerase (UniProt ID: C9LUR0), UTP-glucose-1-phosphate uridyltransferase (UniProt ID: C9LRH1), and imidazole glycerol phosphate synthase (UniProt ID: C9LTU7) as three unique proteins crucial for the S. sputigena life cycle with no substantial similarity to human proteins. These potential drug targets served as the starting point for screening bioactive phytochemicals (1090 compounds) from the Indian Medicinal Plants, Phytochemistry and Therapeutics (IMPPAT) database. Among the screened natural products, cubebin (IMPHY001912) showed a higher affinity for two of the three selected targets, as evidenced by molecular docking and molecular dynamics studies. Given its favorable drug-like profile and possible multitargeting behavior, cubebin could be further exploited as an antibacterial agent for treating S. sputigena-mediated oral infections. It is worth nothing that cubebin could be the active ingredient of appropriate formulations such as mouthwash and/or toothpaste to treat S. sputigena-induced periodontitis, with the advantage of limiting the adverse effects that could affect the use of current drugs. Full article

Clonostachys chloroleuca (formerly classified as C. rosea) is an important mycoparasite active against various plant fungal pathogens. Mitogen-activated protein kinase (MAPK) signaling pathways are vital in mycoparasitic interactions; they participate in responses to diverse stresses and mediate fungal development. In previous studies, the MAPK-encoding gene Crmapk has been proven to be involved in mycoparasitism and the biocontrol processes of C. chloroleuca, but its regulatory mechanisms remain unclear. Aldose 1-epimerases are key enzymes in filamentous fungi that generate energy for fungal growth and development. By protein–protein interaction assays, the glucose-6-phosphate 1-epimerase CrGlu6 was found to interact with Crmapk, and expression of the CrGlu6 gene was significantly upregulated when C. chloroleuca colonized Sclerotinia sclerotiorum sclerotia. Gene deletion and complementation analyses showed that CrGlu6 deficiency caused abnormal morphology of hyphae and cells, and greatly reduced conidiation. Moreover, deletion mutants presented much lower antifungal activities and mycoparasitic ability, and control efficiency against sclerotinia stem rot was markedly decreased. When the CrGlu6 gene was reinserted, all biological characteristics and biocontrol activities were recovered. These findings provide new insight into the mechanisms of glucose-6-phosphate 1-epimerase in mycoparasitism and help to further reveal the regulation of MAPK and its interacting proteins in the biocontrol of C. chloroleuca. Full article

Accumulating evidence indicates that the APOA1 binding protein (AIBP)—a secreted protein—plays a profound role in lipid metabolism. Interestingly, AIBP also functions as an NAD(P)H-hydrate epimerase to catalyze the interconversion of NAD(P)H hydrate [NAD(P)HX] epimers and is renamed as NAXE. Thus, we call it NAXE hereafter. We investigated its role in NAD(P)H-involved metabolism in murine cardiomyocytes, focusing on the metabolism of hexose, lipids, and amino acids as well as mitochondrial redox function. Unbiased metabolite profiling of cardiac tissue shows that NAXE knockout markedly upregulates the ketone body 3-hydroxybutyric acid (3-HB) and increases or trends increasing lipid-associated metabolites cholesterol, α-linolenic acid and deoxycholic acid. Paralleling greater ketone levels, ChemRICH analysis of the NAXE-regulated metabolites shows reduced abundance of hexose despite similar glucose levels in control and NAXE-deficient blood. NAXE knockout reduces cardiac lactic acid but has no effect on the content of other NAD(P)H-regulated metabolites, including those associated with glucose metabolism, the pentose phosphate pathway, or Krebs cycle flux. Although NAXE is present in mitochondria, it has no apparent effect on mitochondrial oxidative phosphorylation. Instead, we detected more metabolites that can potentially improve cardiac function (3-HB, adenosine, and α-linolenic acid) in the Naxe^−/− heart; these mice also perform better in aerobic exercise. Our data reveal a new role of NAXE in cardiac ketone and lipid metabolism. Full article

Rhamnose-associated molecules are attracting attention because they are present in bacteria but not mammals, making them potentially useful as antibacterial agents. Additionally, they are also valuable for tumor immunotherapy. Thus, studies on the functions and biosynthetic pathways of rhamnose-containing compounds are in progress. In this paper, studies on the biosynthetic pathways of three rhamnose donors, i.e., deoxythymidinediphosphate-L-rhamnose (dTDP-Rha), uridine diphosphate-rhamnose (UDP-Rha), and guanosine diphosphate rhamnose (GDP-Rha), are firstly reviewed, together with the functions and crystal structures of those associated enzymes. Among them, dTDP-Rha is the most common rhamnose donor, and four enzymes, including glucose-1-phosphate thymidylyltransferase RmlA, dTDP-Glc-4,6-dehydratase RmlB, dTDP-4-keto-6-deoxy-Glc-3,5-epimerase RmlC, and dTDP-4-keto-Rha reductase RmlD, are involved in its biosynthesis. Secondly, several known rhamnosyltransferases from Geobacillus stearothermophilus, Saccharopolyspora spinosa, Mycobacterium tuberculosis, Pseudomonas aeruginosa, and Streptococcus pneumoniae are discussed. In these studies, however, the functions of rhamnosyltransferases were verified by employing gene knockout and radiolabeled substrates, which were almost impossible to obtain and characterize the products of enzymatic reactions. Finally, the application of rhamnose-containing compounds in disease treatments is briefly described. Full article

Polygonatum sibiricum polysaccharides (PSPs) are used to improve immunity, alleviate dryness, promote the secretion of fluids, and quench thirst. However, the PSP biosynthetic pathway is largely unknown. Understanding the genetic background will help delineate that pathway at the molecular level so that researchers can develop better conservation strategies. After comparing the PSP contents among several different P. sibiricum germplasms, we selected two groups with the largest contrasts in contents and subjected them to HiSeq2500 transcriptome sequencing to identify the candidate genes involved in PSP biosynthesis. In all, 20 kinds of enzyme-encoding genes were related to PSP biosynthesis. The polysaccharide content was positively correlated with the expression patterns of β-fructofuranosidase (sacA), fructokinase (scrK), UDP-glucose 4-epimerase (GALE), Mannose-1-phosphate guanylyltransferase (GMPP), and UDP-glucose 6-dehydrogenase (UGDH), but negatively correlated with the expression of Hexokinase (HK). Through qRT-PCR validation and comprehensive analysis, we determined that sacA, HK, and GMPP are key genes for enzymes within the PSP metabolic pathway in P. sibiricum. Our results provide a public transcriptome dataset for this species and an outline of pathways for the production of polysaccharides in medicinal plants. They also present more information about the PSP biosynthesis pathway at the molecular level in P. sibiricum and lay the foundation for subsequent research of gene functions. Full article