Glucosamine 6-phosphate Research Articles

Plasma Glutaminyl-Peptide Cyclotransferase Mediates Glucosamine-Metabolism-Driven Protection Against Hypertension: A Mendelian Randomization Study

Hypertension is one of the major risk factors for morbidity and mortality worldwide. In this study, Mendelian randomization was utilized to investigate how dietary supplement intake can impact hypertension based on circulating plasma metabolite genome-wide association study (GWAS) datasets, protein quantitative trait loci (pQTLs) of plasma proteins, and multiple public summary-level GWAS data. Pathway enrichment analysis combined with the results of inverse variance weighted Mendelian randomization revealed that a lower risk of hypertension was associated with the dietary intake of glucosamine, an anti-inflammatory supplement: odds ratio (OR) (95% CI): 0.888 (0.824–0.958). Additionally, glucosamine 6-phosphate N-acetyltransferase was identified as a protective factor against hypertension, OR (95% CI): 0.995 (0.992–0.998), shedding light on the potential protective mechanism of glucosamine. Mediation Mendelian randomization indicated that the protective effect of glucosamine metabolism was mediated by glutaminyl-peptide cyclotransferase, with a mediation proportion of 12.1% (5.9–18.2%), p < 0.05. This study offers new insights into preventive strategies for individuals with hypertension risk.

The Possible Roles of Glucosamine-6-Phosphate Deaminases in Ammonium Metabolism in Cancer

Nearly 5% of the glucose-6-phosphate (Glc6P) in cells is diverted into the hexosamine biosynthetic pathway (HBP) to synthesize glucosamine-6-phosphate (GlcN6P) and uridine diphosphate N-acetyl-glucosamine-6-phosphate (UDP-GlcN6P). Fructose-6-phosphate (Fru6P) is a common intermediary between glycolysis and the HBP. Changes in HBP regulation cause abnormal protein N-glycosylation and O-linked-N-acetylglucosamine modification (O-GlcNAcylation), affecting protein function and modifying cellular responses to signals. The HBP enzymes glucosamine-6-phosphate deaminases 1 and 2 (GNPDA1 and 2) turn GlcN6P back into Fru6P and ammonium, and have been implicated in cancer and metabolic diseases. Despite the plentiful literature on this topic, the mechanisms involved are just beginning to be studied. In this review, we summarize, for the first time, the current knowledge regarding the possible roles of the isoenzymes of both GNPDAs in the pathogenesis and development of metabolic diseases and cancer from a molecular point of view, highlighting their importance not only in supplying carbon from glycolysis, but also in ammonia metabolism.

An Integrative Computational Approach for Design and Evaluation of Novel [1,2,4]triazolo[3,4-b][1,3,4]thiadiazole Analogues as Dual-Action Anti-Retroviral and Anti-Bacterial Agents: Insights into Rational Drug Design Strategies

The development of effective antiretroviral inhibitors (HIV-1 Reverse Transcriptase) and glucosamine-6-phosphate (GlcN6P) agents represent a significant challenge for combating viral infections and related diseases. In this study, we employed a multidisciplinary approach to design and evaluate a series of novel triazole analogs as potential candidates for anti-retroviral and glucosamine-6-phosphate agents. Using molecular docking, we explored the binding interactions between the RSA3 analog and the target proteins implicated in viral replication and glucosamine metabolism. Density functional theory (DFT) employing the 6-311++G(d,p) basis set was utilized for computational analysis, with a subsequent examination of the electronic parameters. The HOMO and LUMO orbitals as well as the molecular electrostatic potential map were investigated using DFT to characterize the reactivity of our molecule. Molecular dynamics simulations were performed to investigate the stability and dynamic behavior of the ligand-protein complex (RSA3) over time (300 ns). Furthermore, we employed MM-GBSA calculations of the compound RSA3 (molecular mechanics generalized band surface area) to estimate the binding free energies (−71.30 ± 7.26 kcal/mol and −67.86 ± 7.09 kcal/mol, respectively) and identified the most promising compounds with high affinity for the target proteins. Additionally, predictive absorption, distribution, metabolism, excretion and toxicity (ADMET) studies of compound RSA3 were conducted to assess its drug-like properties and potential safety profiles of the selected compound. Our results revealed that RSA3 has favorable binding interactions, is a stable complex and has significant binding affinity for target proteins. Moreover, predictive ADMET studies indicated that RSA3 possesses desirable drug-like properties, suggesting its potential for further investigation as an anti-retroviral agent and glucosamine-6-phosphate agent. Overall, this integrative computational approach combining molecular docking, DFT analysis, dynamics simulations, MM-GBSA and predictive ADMET studies provides valuable insights into the design and evaluation of novel triazole analogs with potential therapeutic applications, highlighting the importance of rational drug design strategies in the field of antiretroviral and glucosamine research.

GNPNAT1 Serves as a Prognostic Biomarker Correlated with Immune Infiltration and Promotes Cancer Cell Metastasis through Stabilization of Snai2 in Lung Adenocarcinoma.

Lung cancer is a common malignant tumor with high morbidity and mortality rate. Glucosamine 6-phosphate N-acetyltransferase (GNPNAT1), which serves as a critical enzyme in hexosamine biosynthetic pathway (HBP), has been identified as a metastasis-associated gene and is upregulated in lung adenocarcinoma (LUAD). However, the exact role and related mechanism of GNPNAT1 in LUAD metastasis remain unknown. We analyzed the expression of GNPNAT1 in the public databases and confirmed the results by immunohistochemistry (IHC). The biological functions of GNPNAT1 in LUAD were investigated based on The Cancer Genome Atlas (TCGA). Correlations between GNPNAT1 and cancer immune characteristics were analyzed via the Estimation of Stromal and Immune cells in Malignant Tumor tissues using Expression data (ESTIMATE) and Cell-type Identification by Estimating Relative Subsets of RNA Transcript (CIBERSORT) R package. The underlying mechanisms of altered GNPNAT1 expression on LUAD cell tumorigenesis, proliferation, migration, invasion, and metastasis were explored in vitro and in vivo. We demonstrated that GNPNAT1 expression was significantly increased in LUAD and negatively associated with the overall survival (OS) of patients. hsa-miR-1-3p and hsa-miR-26a-5p were identified as upstream miRNA targets of GNPNAT1. GNPNAT1 was associated with the infiltration levels of CD8 T cells, memory-activated CD4 T cells, NK cells resting, macrophages M0, macrophages M1, neutrophils, gamma delta T cells, and eosinophils, while it was negatively correlated with memory-resting CD4 T cells, regulatory T cells (Tregs), resting NK cells, monocytes, resting dendritic cells, and resting mast cells. GNPNAT1 knockdown significantly inhibited proliferation, migration, invasion, epithelial-mesenchymal transition (EMT) process, and metastasis of LUAD cells, while overexpression of GNPNAT1 revealed the opposite effects. Rescue assay showed that Snai2 knockdown reversed GNPNAT1-induced LUAD cells migration, invasion, and EMT. Mechanistically, GNPNAT1 promoted cancer cell metastasis via repressing ubiquitination degradation of Snai2 in LUAD. Taken together, these data indicate that GNPNAT1 serves as a prognostic biomarker for LUAD patient. Additionally, GNPNAT1 is critical for promoting tumorigenesis and metastasis of LUAD cells and may be a potential therapeutic target for preventing LUAD metastasis.

Dissecting the manipulation of lufenuron on chitin synthesis in Helicoverpa armigera

Lufenuron, a benzoylurea chitin synthesis inhibitor, is effective against many insect pests. However, the insecticidal activity of lufenuron has not been completely elucidated, nor has its disturbing effect on chitin synthesis genes. In this study, bioassay results demonstrated an outstanding toxicity of lufenuron against Helicoverpa armigera larvae. The treated larvae died from abortive molting and metamorphosis defects, and severe separation of epidermis and subcutaneous tissues was observed. Treatment of 3rd- and 4th-instar larvae with LC25 lufenuron significantly extended the duration of larval and pupal stage, reduced the rates of pupation and emergence, and adversely affected pupal weight. Besides, lufenuron can severely reduce chitin content in larval integument, and the lufenuron-treated larvae showed reduced trehalose content in their hemolymph. Further analysis using RNA sequencing revealed that five chitin synthesis genes were down-regulated, whereas the expressions of two chitin degradation genes were significantly enhanced. Knockdown of chitin synthase 1 (HaCHS1), uridine diphosphate-N-acetylglucosamine-pyrophosphorylase (HaUAP), phosphoacetyl glucosamine mutase (HaPGM), and glucosamine 6-phosphate N-acetyl-transferase (HaGNPAT) in H. armigera led to significant increase in larval susceptibilities to LC25 lufenuron by 75.48%, 65.00%, 68.42% and 28.00%, respectively. Our findings therefore revealed the adverse effects of sublethal doses of lufenuron on the development of H. armigera larvae, elucidated the perturbations on chitin metabolism, and proved that the combination of RNAi and lufenuron would improve the control effect of this pest.

Synthesis, antibacterial, antibiofilm, and docking studies of chalcones against multidrug resistance pathogens

The escalating threat of drug-resistant microbes underscores the urgent need for novel antimicrobial agents. In response, considerable research effort has been directed towards developing innovative frameworks and strategies to address this challenge. Chalcones, known for their broad-spectrum biological activities, have emerged as promising candidates for combating drug resistance. In this study, a series of 2′-Hydroxychalcones (5a, 5b, 5c, and 5d) with varying electron withdrawing and donating groups were synthesized via Claisen Schmidt condensation. FT-IR, 1H NMR, and 13C NMR analyses were employed to confirm the structure of the synthesized compounds. Subsequent evaluation of the synthesized compounds revealed their potential as antibacterial and antibiofilm agents. Notably, compounds 5a and 5d exhibited potent antibacterial activity against multidrug-resistant (MDR) bacteria E. coli, P. aeruginosa, K. pneumoniae, and S. aureus, surpassing the reference drug Ciprofloxacin (30 μg/mL) and other synthesized compounds. Compound 5d showed a notable 19.5 mm zone of inhibition against K. pneumoniae. Furthermore, 5a (at a concentration of 30 μg) and 5d (at a concentration of 50 μg) exhibited statistically significant (P > 0.05) biofilm inhibition efficacy compared to Ciprofloxacin (30 μg/mL). The synthesized chalcones 5a-5d were also docked via PachDock molecular docking software for Glucosamine-6-phosphate (GlcN-6-P) synthase inhibition and showed that ligand 5a exhibited outstanding results with score 4238 and ACE value −160.89 kcal/mol, consistent with the observed antibacterial activity. These findings underscore the potential of chalcones, particularly 5a and 5d, as promising candidates for the development of new antimicrobial agents targeting drug-resistant microbes and biofilm formation.

Identifying Chlorella vulgaris and Chlorella sorokiniana as sustainable organisms to bioconvert glucosamine into valuable biomass

Chitin is a major component of various wastes such as crustacean shells, filamentous fungi, and insects. Recently, food-safe biological and chemical processes converting chitin to glucosamine have been developed. Here, we studied microalgae that can uptake glucosamine as vital carbon and nitrogen sources for valuable alternative protein biomass. Utilizing data mining and bioinformatics analysis, we identified 29 species that contain the required enzymes for glucosamine to glucose conversion. The growth performance of the selected strains was examined, and glucosamine was used in different forms and concentrations. Glucose at a concentration of 2.5 g/L was required to initiate glucosamine metabolic degradation by Chlorella vulgaris and Chlorella sorokiniana. Glucosamine HCl and glucosamine phosphate showed maximum cell counts of about 8.5 and 9.0 log/mL for C. sorokiniana and C. vulgaris in 14 days, respectively. Enzymatic hydrolysis of glucosamine increased growth performance with C. sorokiniana by about 3 folds. The adapted strains were fast-growing and could double their dry biomasses during the same incubation time. In addition, adapted C. sorokiniana was able to tolerate three times glucosamine concentration in the medium. The study illustrated possible strategies for employing C. sorokiniana and C. vulgaris to convert glucosamine into valuable biomass in a more sustainable way.

Systems-wide analysis of the ROK-family regulatory gene rokL6 and its role in the control of glucosamine toxicity in Streptomyces coelicolor.

Central metabolism plays a key role in the control of growth and antibiotic production in streptomycetes. Specifically, aminosugars act as signaling molecules that affect development and antibiotic production, via metabolic interference with the global repressor DasR. While aminosugar metabolism directly connects to other major metabolic routes such as glycolysis and cell wall synthesis, several important aspects of their metabolism are yet unresolved. Accumulation of N-acetylglucosamine 6-phosphate or glucosamine 6-phosphate is lethal to many bacteria, a yet unresolved phenomenon referred to as "aminosugar sensitivity." We made use of this concept by selecting for suppressors in genes related to glucosamine toxicity in nagB mutants, which showed that the gene pair of rok-family regulatory gene rokL6 and major facilitator superfamily transporter gene sco1448 forms a cryptic rescue mechanism. Inactivation of rokL6 resulted in the expression of sco1448, which then prevents the toxicity of amino sugar-derived metabolites in Streptomyces. The systems biology of RokL6 and its transcriptional control of sco1448 shed new light on aminosugar metabolism in streptomycetes and on the response of bacteria to aminosugar toxicity.

Phosphonate and Thiasugar Analogues of Glucosamine-6-phosphate: Activation of the glmS Riboswitch and Antibiotic Activity.

The glmS riboswitch is a motif found in 5'-untranslated regions of bacterial mRNA that controls the synthesis of glucosamine-6-phosphate (GlcN6P), an essential building block for the bacterial cell wall, by a feedback mechanism. Activation of the glmS riboswitch by GlcN6P mimics interferes with the ability of bacteria to synthesize its cell wall. Accordingly, GlcN6P mimics acting as glmS activators are promising candidates for future antibiotic drugs that may overcome emerging bacterial resistance against established antibiotics. We describe the synthesis of a series of phosphonate mimics of GlcN6P as well as the thiasugar analogue of GlcN6P. The phosphonate mimics differ in their pKa value to answer the question of whether derivatives with a pKa matching that of GlcN6P would be efficient glmS activators. We found that all derivatives activate the riboswitch, however, less efficiently than GlcN6P. This observation can be explained by the missing hydrogen bonds in the case of phosphonates and is valuable information for the design of future GlcN6P mimics. The thiasugar analogue of GlcN6P on the other hand turned out to be a glmS riboswitch activator with the same activity as the natural metabolite GlcN6P. The nonphosphorylated thiasugar displayed antimicrobial activity against certain bacilli. Therefore, the compound is a promising lead structure for the development of future antibiotics with a potentially novel mode of action.

In-silico prediction and in vitro validation of antioxidant, antibacterial and antifungal potential of Black Turmeric (Curcuma caesia Roxb.) essential oils and its constituents

The growing interest in the health and pharmaceutical industries has led to a significant increase in demand for essential oils. Curcuma caesia, as a member of the Zingiberaceae family, has been used for its high-quality essential oils (EOs) with remarkable therapeutic properties. The current study aimed at predicting the in-silico interactions of C. caesia volatile constituents against the protein responsible for oxidative and microbial stress in order to investigate their potential for industrial and pharmaceutical applications. The accuracy of the in-silico predictions was confirmed by carrying out the in vitro validation of the antioxidant, antibacterial, and antifungal activity of the EOs derived from the rhizome and leaves, as well as its volatile constituents. EOs from the rhizome and leaf samples of C. caesia were extracted through the hydro distillation method and yielded a percentage (%) of 1.80 ± 0.02 and 0.95 ± 0.02 (fresh weight basis, v/w), respectively. A total of 38 and 29 volatile constituents were identified in the rhizome and leaf EOs by gas-chromatography mass spectrometry analysis, representing 92.55% and 90.75% of the total peak area, respectively. The rhizome and leaf EOs showed oxygenated sesquiterpene (39.91% and 27.69%) as the predominate fractions followed by sesquiterpene hydrocarbons (13.36% and 18.44%). Curzerenone (18.09%), epicurzerenone (12.47%), eucalyptol (11.57%), camphor (5.94%), and germacrone (4.47%) were the major constituents in the rhizome EO, whereas, the leaf EO was dominated by eucalyptol (12.53%), camphor (7.23%), curzerenone (5.24%), germacrone (4.81%) and curzerene (4.9%). The in vitro biological activities such as antioxidant, antibacterial, and antifungal potential of C. caesia EOs were evaluated. The antioxidant evaluation using enzymatic and non-enzymatic assays, showed excellent potential of C. caesia EOs as compared to standard drugs. Specifically, in the enzymatic assay, leaf EO of C. caesia was resulted into the reduction of ROS and an increase in the activity of superoxide dismutase (SOD), catalase (CAT), and glutathione S-transferase (GST) in OZ-stimulated PMNs. The EOs also displayed a remarkable antibacterial activity against Staphylococcus aureus, elucidating it as the most susceptible strain. Further, the in-silico prediction of the constituents was conducted using Swiss-ADME, and molecular docking analysis. Swiss-ADME revealed the drug-likeness and safety properties of constituents present in C. caesia EOs. The molecular docking study was carried out to interpret the possible interactions of phytoconstituents qualified in the Swiss-ADME study with two bacterial proteins (Tyrosyl-tRNA synthetase from Staphylococcus aureus (PDB ID: 1JIJ) and Glucosamine 6-phosphate synthase from Escherichia coli (PDB ID: 1XFF)), one fungal protein (N-myristoyl transferase from Candida albicans (PDB ID: 1IYL)) and one oxidative protein (Human peroxiredoxin 5 (PDB ID: 1HD2)). Furthermore, to validate the result of molecular docking, the biological activity of higher affinity constituents was also evaluated. As a result, the in vitro findings supported the in-silico prediction. Therefore, C. caesia or its constituents like curzerenone, camphor, eucalyptol, epicurzerenone, germacrone, viridifloral, muurola-4,10(14)-dien-1-ol, and globulol might be a valuable source for developing antioxidant and antimicrobial drugs. To the best of present author’s knowledge, this is the first scientific report on the in-silico prediction of C. caesia constituents against bacterial, fungal and oxidative proteins through molecular docking, which may contribute to the development of various alternatives against multi-drug resistance.

Deconvolution of multichannel LC-MS/MS chromatograms of glucosamine-phosphates: Evidence of a GlmS regulatory difference between Staphylococcus aureus and Enterococcus faecium

Resolving isomeric analytes is challenging given their physical similarity – making chromatographic resolution difficult, and their identical masses – making simple mass resolution impossible. MS/MS data provides a means to resolve isomeric analytes if their MS/MS intensity profiles are sufficiently different. Glucosamine-6-phosphate (GlcN-6P) and glucosamine-1-phosphate (GlcN-1P) are early bacterial cell wall intermediates. These and other isomeric hexosamine-phosphates are highly polar and unretained on reverse-phase chromatography media. Three commercially available hexosamine-phosphate standards (GlcN-6P, GlcN-1P, and GalN-1P) were derivatized with octanoic anhydride, and chromatographic conditions were established to resolve these analytes on C18 columns. GlcN-1P and GalN-1P overlapped chromatographically under all tested chromatography conditions. Three MS/MS fragments (79, 97, and 199 m/z) were common to all three commercially available hexosamine-phosphates. Intensity ratios of the three MS/MS fragments from these three hexosamine-phosphate standards were used to deconvolute mixture chromatograms of these standards by non-negative linear regression. This approach allowed the complete resolution of these analytes. The chromatographically overlapping GlcN-1P and GalN-1P, which shared similar but modestly different MS/MS intensity profiles, were fully resolved with this non-negative deconvolution approach. This approach was then applied to MRSA, VSE, and VRE bacterial extracts before and after exposure to vancomycin. This demonstrated a substantial (3-fold) increase in GlcN-6P in vancomycin-treated MRSA samples but not in vancomycin-treated VSE or VRE samples. These observations appear to localize previously observed differences between MRSA and VRE/VSE peptidoglycan biosynthesis regulation to GlmS, which synthesizes GlcN-6P and is the product of a regulatory ribozyme sensitive to the levels of GlcN-6P

The Transcription Factor CcRlm1 Regulates Cell Wall Maintenance and Poplar Defense Response by Directly Targeting CcChs6 and CcGna1 in Cytospora chrysosperma.

Maintenance of cell wall integrity is important for fungal cell morphology against external stresses and even virulence. Although the transcription factor Rlm1 is known to play major regulatory roles in the maintenance of cell integrity, the underlying mechanism of how Rlm1 contributes to cell wall integrity and virulence in phytopathogenic fungi remains unclear. Here, we demonstrated that CcRlm1 plays important roles in cell wall maintenance and virulence in the poplar canker fungus Cytospora chrysosperma. Among putative downstream targets, CcChs6 (chitin synthase) and CcGna1 (glucosamine 6-phosphate N-acetyltransferase) were found to be direct targets of CcRlm1 and shown to function in chitin synthesis and virulence. Furthermore, we found stronger induction of poplar defense responses when challenged with these gene deletion mutants. Collectively, these results suggest that CcRlm1 plays a critical role in the regulation of cell wall maintenance, stress response, and virulence by directly regulating CcChs6 and CcGna1 in C. chrysosperma. IMPORTANCE Cytospora chrysosperma causes canker diseases on woody plants, and the molecular basis of its infection is not well understood. This study shows that CcRlm1 is the major regulator of chitin synthesis and virulence of the poplar canker fungus. Our research contributes to further understanding the molecular basis of the interaction between C. chrysosperma and poplar.

Substrate Binding in the Allosteric Site Mimics Homotropic Cooperativity in the SIS-fold Glucosamine-6-phosphate Deaminases.

Glucosamine-6-phosphate (GlcN6P) deaminases from E. coli (EcNagBI) and S. denitrificans (SdNagBII) are special examples of what constitute non-homologous isofunctional enzymes due to their convergence, not only in catalysis, but also in cooperativity and allosteric properties. Additionally, we found that the sigmoidal kinetics of SdNagBII cannot be explained by the existing models of homotropic activation. This study describes the regulatory mechanism of SdNagBII using enzyme kinetics, isothermal titration calorimetry (ITC), and X-ray crystallography. ITC experiments revealed two different binding sites with distinctive thermodynamic signatures: a single binding site per monomer for the allosteric activator N-acetylglucosamine 6-phosphate (GlcNAc6P) and two binding sites per monomer for the transition-state analog 2-amino-2-deoxy-D-glucitol 6-phosphate (GlcNol6P). Crystallographic data demonstrated the existence of an unusual allosteric site that can bind both GlcNAc6P and GlcNol6P, implying that the homotropic activation of this enzyme arises from the occupation of the allosteric site by the substrate. In this work we describe the presence of this novel allosteric site in the SIS-fold deaminases, which is responsible for the homotropic and heterotropic activation of SdNagBII by GlcN6P and GlcNAc6P, respectively. This study unveils an original mechanism to generate a high degree of homotropic activation in SdNagBII, mimicking the allosteric and cooperative properties of hexameric EcNagBI but with a reduced number of subunits. This article is protected by copyright. All rights reserved.

GNPNAT1 is a potential biomarker correlated with immune infiltration and immunotherapy outcome in breast cancer.

Glucosamine 6-phosphate N-acetyltransferase (GNPNAT1) is a crucial enzyme involving hexosamine biosynthesis pathway and is upregulated in breast cancer (BRCA). However, its biological function and mechanism on patients in BRCA have not been investigated. In this study, the differential expression of GNPNAT1 was analyzed between BRCA tissues and normal breast tissues using the Cancer Genome Atlas (TCGA) database and Gene Expression Omnibus (GEO) database, which was validated by quantitative real-time polymerase chain reaction, Western blot and immunohistochemistry. Then, the potential clinical value of GNPNAT1 in BRCA was investigated based on TCGA database. Functional enrichment analyses, including Gene Ontology, Kyoto Encyclopedia of Genes and Genomes, Gene Set Variation Analysis, were performed to explore the potential signaling pathways and biological functions involved in GNPNAT1 in BRCA. Tumor immune infiltration was analyzed using ESTIMATE, CIBERSORT and TISIDB database; and immune therapy response scores were assessed using TIDE. Finally, Western blot, Cell counting kit-8 and Transwell assay were used to determine the proliferation and invasion abilities of breast cancer cells with GNPNAT1 knockdown. GNPNAT1 was up-regulated in BRCA tissues compared with normal tissues which was subsequently verified in different cell lines and clinical tissue samples. Based on TCGA and GEO, the overexpression of GNPNAT1 in BRCA contributed to a significant decline in overall survive and disease specific survive. Functional enrichment analyses indicated that the enriched pathways in high GNPNAT1 expression group included citrate cycle, N-glycan biosynthesis, DNA repair, and basal transcription factors. Moreover, the overexpression of GNPNAT1 was negatively correlated with immunotherapy response and the levels of immune cell infiltration of CD8+ T cells, B cells, natural killer cells, dendritic cells and macrophages. Knockdown of GNPNAT1 impairs the proliferation and invasion abilities of breast cancer cells. GNPNAT1 is a potential diagnostic, prognostic biomarker and novel target for intervention in BRCA.

Evolution of pathogenicity-associated genes in Rhizoctonia solani AG1-IA by genome duplication and transposon-mediated gene function alterations

BackgroundRhizoctonia solani is a polyphagous fungal pathogen that causes diseases in crops. The fungal strains are classified into anastomosis groups (AGs); however, genomic complexity, diversification into the AGs and the evolution of pathogenicity-associated genes remain poorly understood.ResultsWe report a recent whole-genome duplication and sequential segmental duplications in AG1-IA strains of R. solani. Transposable element (TE) clusters have caused loss of synteny in the duplicated blocks and introduced differential structural alterations in the functional domains of several pathogenicity-associated paralogous gene pairs. We demonstrate that the TE-mediated structural variations in a glycosyl hydrolase domain and a GMC oxidoreductase domain in two paralogous pairs affect the pathogenicity of R. solani. Furthermore, to investigate the association of TEs with the natural selection and evolution of pathogenicity, we sequenced the genomes of forty-two rice field isolates of R. solani AG1-IA. The genomic regions with high population mutation rates and with the lowest nucleotide diversity are enriched with TEs. Genetic diversity analysis predicted the genes that are most likely under diversifying and purifying selections. We present evidence that a smaller variant of a glucosamine phosphate N-acetyltransferase (GNAT) protein, predicted to be under purifying selection, and an LPMP_AA9 domain-containing protein, predicted to be under diversifying selection, are important for the successful pathogenesis of R. solani in rice as well as tomato.ConclusionsOur study has unravelled whole-genome duplication, TE-mediated neofunctionalization of genes and evolution of pathogenicity traits in R. solani AG1-IA. The pathogenicity-associated genes identified during the study can serve as novel targets for disease control.

CRISPR-dCas12a-mediated genetic circuit cascades for multiplexed pathway optimization.

The production efficiency of microbial cell factories is sometimes limited by the lack of effective methods to regulate multiple targets in a coordinated manner. Here taking the biosynthesis of glucosamine-6-phosphate (GlcN6P) in Bacillus subtilis as an example, a 'design-build-test-learn' framework was proposed to achieve efficient multiplexed optimization of metabolic pathways. A platform strain was built to carry biosensor signal-amplifying circuits and two genetic regulation circuits. Then, a synthetic CRISPR RNA array blend for boosting and leading (ScrABBLE) device was integrated into the platform strain, which generated 5,184 combinatorial assemblies targeting three genes. The best GlcN6P producer was screened and engineered for the synthesis of valuable pharmaceuticals N-acetylglucosamine and N-acetylmannosamine. The N-acetylglucosamine titer reached 183.9 g liter-1 in a 15-liter bioreactor. In addition, the potential generic application of the ScrABBLE device was also verified using three fluorescent proteins as a case study.

Structure of a bacterial ribonucleoprotein complex central to the control of cell envelope biogenesis

Biogenesis of the essential precursor of the bacterial cell envelope, glucosamine‐6‐phosphate (GlcN6P), is controlled by intricate post‐transcriptional networks mediated by GlmZ, a small regulatory RNA (sRNA). GlmZ stimulates translation of the mRNA encoding GlcN6P synthtase in Escherichia coli, but when bound by RapZ protein, the sRNA becomes inactivated through cleavage by the endoribonuclease RNase E. Here, we report the cryoEM structure of the RapZ:GlmZ complex, revealing a complementary match of the RapZ tetrameric quaternary structure to structural repeats in the sRNA. The nucleic acid is contacted by RapZ mostly through a highly conserved domain that shares an evolutionary relationship with phosphofructokinase and suggests links between metabolism and riboregulation. We also present the structure of a precleavage intermediate formed between the binary RapZ:GlmZ complex and RNase E that reveals how GlmZ is presented and recognised by the enzyme. The structures provide a framework for understanding how other encounter complexes might guide recognition and action of endoribonucleases on target transcripts, and how structured substrates in polycistronic precursors may be recognised for processing by RNase E.

Carba-Sugar Analogs of Glucosamine-6-Phosphate: New Activators for the glmS Riboswitch.

Riboswitches are 5'-untranslated mRNA regions mostly found in bacteria. They are promising drug targets to overcome emerging bacterial resistance against commonly used antibiotics. The glmS riboswitch is unique among the family of riboswitches as it is a ribozyme that undergoes self-cleavage upon binding to glucosamine-6-phosphate (GlcN6P). Previously, we showed that carba glucosamine-6-phosphate (carba-GlcN6P) induces self-cleavage of the riboswitch with a potency similar to that of GlcN6P. Here, we report a synthetic approach to a new class of carba-GlcN6P derivatives with an alkoxy substituent in the carba position. Key features of the synthesis are a ring closing metathesis followed by a hydroboration. The strategy gives access to libraries of carba-GlcN6P derivatives. Ribozyme cleavage assays unraveled new activators for the glmS riboswitch from Listeria monocytogenes and Clostridium difficile.

Elucidating the catalytic mechanism of a bacterial deglycase essential for utilization of fructose‐lysine, an Amadori product

Amadori products are stable sugar‐amino acid conjugates that are formed non‐enzymatically via the Maillard reaction that takes place during preparation of foods by heating, roasting, and drying. Fructose‐lysine (F‐Lys, ε‐conjugated) is one of the most abundant Amadori compounds in processed foods and is a key intermediate in the formation of advanced glycation end products, which in turn are implicated in inflammation and disease. The variation among humans in their ability to metabolize F‐Lys has motivated an examination of the inter‐individual differences in gut microbial taxa and the enzymes that help convert F‐Lys into short‐chain fatty acids or cellular energy. Results from such studies are also expected to yield insights into whether F‐Lys utilization by bacterial pathogens (e.g., Escherichia coli, Salmonella enterica serovar Typhimurium) might offer them a competitive edge. Either during or after bacterial uptake, F‐Lys is phosphorylated to form 6‐phosphofructose‐lysine (6‐P‐F‐Lys). FrlB, a deglycase, converts 6‐P‐F‐Lys to L‐lysine and glucose 6‐phosphate, with the latter feeding into glycolysis. Since the catalytic mechanism of FrlB has not been studied, we sought to obtain a high‐resolution structure of Salmonella FrlB ± 6‐P‐F‐Lys and identify the active‐site residues essential for catalysis.After overexpression and purification of recombinant Salmonella FrlB, we obtained its 1.9 Å crystal structure. FrlB exists as a dimer with two identifiable inter‐subunit active sites. In the absence of a co‐crystal structure of FrlB with 6‐P‐F‐Lys, we took two different strategies to delineate its catalytic pocket. First, we observed that the phosphosugar‐binding module–called the sugar isomerase (SIS) domain in FrlB–shared sequence similarity with the eponymous domain in E. coli glucosamine 6‐phosphate synthase (GlmS), which generates glucosamine 6‐phosphate from fructose 6‐phosphate (F‐6‐P) and glutamine. Overlaying the tertiary structures of Salmonella FrlB with E. coli GlmS, which had previously been co‐crystallized with F‐6‐P, helped identify FrlB residues that could be involved in 6‐P‐F‐Lys binding and cleavage. Second, sequence alignment of Salmonella FrlB with FraB, a related and biochemically characterized deglycase required for metabolism of fructose‐asparagine (an Amadori compound) pinpointed residues that could act as a general acid and a general base during deglycation. From these comparative analyses, six candidate residues in FrlB were individually mutated to alanine or another conservative substitution, and the mutant derivatives were purified using affinity chromatography. Our differential scanning fluorimetry studies revealed that all the mutants exhibit thermal stability nearly identical to wild‐type FrlB; importantly, our native mass spectrometry (nMS) studies confirmed that the mutations did not impair the ability of these mutants to form a stable dimer. A spectrophotometric coupled assay was employed to measure the activity of FrlB and the panel of mutants. When a mutation dampened or eliminated deglycase activity, nMS was leveraged to distinguish between a defect in substrate binding versus cleavage. Collectively, our results provide a platform for defining the active site and catalytic mechanism of FrlB even while highlighting the value of exploiting structures of distant homologs to advance structure‐function relationship studies.

GFAT1 is highly expressed in cancer stem cells of pancreatic cancer.

BackgroundCancer stem cells (CSCs) play pivotal roles in the growth, invasion, metastasis, and chemoresistance of pancreatic cancer (PC). The current characterization of CSCs in PC is not complete. Glutamine-fructose-6-phosphate transaminase 1 (GFAT1) is a key enzyme that regulates the hexosamine pathway (HP), in which it not only controls glucose influx but also catalyzes the reaction to form glucosamine 6-phosphate. Recently, it was reported that GFAT1 is highly expressed in PC. However, the relevance of this high expression of GFAT1, especially its association with cancer stemness, has not been well defined and is thus addressed in the current study.MethodsGFAT1 levels were determined in PC from a public database and assessed by bioinformatics tools. GFAT1 expression in CD133+ and CD44+ CSCs in PC was analyzed by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and immunostaining on cytospun cells after flow cytometry-based cell sorting. GFAT1+ cells were separated from GFAT1− cells by transfection of PC cell lines with a designed plasmid that expressed red fluorescent protein (RFP) under a GFAT1 promoter. Tumor sphere formation, tumor growth, tumor cell invasion, cell migration, and the resistance to gemcitabine-induced apoptosis were determined in GFAT1+ vs. GFAT1− PC cells.ResultsGFAT1 levels were significantly upregulated in PC compared to the adjacent non-PC tissue. There were significantly more GFAT1+ cells in the CD133+ population than in the CD133− population, and similarly, there were significantly more GFAT1+ cells in the CD44+ population than in the CD44− population. Compared to GFAT1− PC cells, GFAT1+ PC cells generated significantly more tumor spheres in culture, appeared to be more invasive and migratory, and were significantly more resistant to gemcitabine-induced cell apoptosis.ConclusionsGFAT1 is highly expressed in CSCs among PC cells and may be crucial for PC growth, metastasis, and chemoresistance.