Cell Wall Biosynthesis Research Articles

Glycosyltransferases: Unraveling Molecular Insights and Biotechnological Implications

Glycosyltransferases (GTs) are present in almost all living organisms; plants, animals and microorganisms. GTs transfer sugar molecule from nucleotide sugars to a wide range of molecules including hormones, secondary metabolites, biotic and abiotic chemicals. When glycosyltransferases add a sugar moiety in any molecule, the hydrophilicity of that molecule changes and thus alter the chemical properties of the molecule. This phenomenon is vital for appropriate working of living organisms. For the first time, X-ray structure of bacteriophage T4-glucosyltransferase was reported in 1994. In bacteria, GTs play essential roles in various biological processes such as cell wall biosynthesis, surface glycosylation and virulence factor production. The point mutation as well as the domain-swapping has been reported in Bacteria. The sequence change as well as the whole cells has been engineered in bacteria too. GTs play very important role in survival, growth, development, metabolism, detoxification, insecticide resistance, chitin formation, chemosensation, defense and immunity, involved in various signaling pathways, etc. In plants, glycosyltransferase enzymes play essential role in biosynthesis of cell wall components, secondary metabolites, and signaling molecules. GTs are involved in the transfer of sugar moieties from activated donor molecules to specific acceptor molecules, leading to the formation of glycosidic bonds. GTs modify flavonoids, alkaloids and terpenoids, etc. with sugar residues and alter the solubility, stability, and bioactivity of these compounds and regulate the plant defense mechanism and interaction with insects, microorganisms and other organisms. GTs have direct impact on plant homeostasis. Site directed mutagenesis (SDM) in UGTs or GTs cause a change in substrate specificity and produce increased or total loss in the catalytic activity GTs. This kind of change demonstrated that a change in substrate specificity could cause better glycosylation and perked up anticancer activity of UGTs. GTs are also involved in glycosylaton of phytohormones and regulate their metabolism and signaling pathways. GTs are involved in the activity, stability, and transport of these hormones and influence the plant growth, development, and responses to various environmental stimuli. Four UGT families encoding 200 genes are reported in humans which regulate cell signaling, protein folding, immune response, growth and development, detoxification, metabolism and elimination of drugs, DNA methylation and histone modifications, transcriptional regulation, post-transcriptional regulation and post-translational regulation, synthesis of human blood group antigens A and B and recently GTs are also reported as linked with COVID-19-related loss of smell or taste. Various bioinformatics tools have been developed which would help analyse in silico, the structure of the GTs using any reference enzyme. The activity and the ordered structures along with various stability assays can be performed before to conduct in vitro analyses such as mutagenesis. Targeted mutagenesis have been reported through site directed mutagenesis (SDM) or domain-swapping. Standard protocols of molecular biology i.e. transformation, protein expression, extraction and purification followed by mass spectrometric analysis has been described. This molecular technique would direct future endeavours to engineer more glycosyltransferases to augment their activity with different substrates and provide a basis for more exploration of GTs as an active compound for potential anti-cancer therapeutics. Additionally, the role of GTs in medicine, food industry, pharmaceutical industry and agriculture is discussed. More research work is needed for the better understanding of the biological processes and the mechanisms of glycosyltransferases involved in cancer, tumor, drug metabolism etc. New era of engineering is awaited to engineer these GT enzymes in vitro to get them boost in industry as well as to help cure cancer and other diseases as well.

Parasitic dodder expresses an arsenal of secreted cellulases with multi-substrate specificity during host invasion

Cuscuta campestris is a common and problematic parasitic plant which relies on haustoria to connect to and siphon nutrients from host plants. Glycoside hydrolase family 9 (GH9) cellulases (EC 3.2.1.4) play critical roles in plant cell wall biosynthesis and disassembly, but their roles during Cuscuta host invasion remains underexplored. In this study, we identified 22 full-length GH9 cellulase genes in C. campestris genome, which encoded fifteen secreted and seven membrane-anchored cellulases that showed distinct phylogenetic relationships. Expression profiles suggested that some of the genes are involved in biosynthesis and remodeling of the parasite's cell wall during haustoriogenesis, while other genes encoding secreted B- and C-type cellulases are tentatively associated with degrading host cell walls during invasion. Transcriptomic data in a host-free system and in the presence of susceptible or partially resistant tomato hosts, showed for especially GH9B7, GH9B11 and GH9B12 a shift in expression profiles in the presence of hosts, being more highly expressed during host attachment, indicating that Cuscuta can tune cellulase expression in response to a host. Functional analyses of recombinant B- and C-type cellulases showed endoglucanase activities over wide pH and temperature conditions, and activities towards multiple cellulose and hemicellulose substrates. These findings improve our understanding of host cell wall disassembly by Cuscuta, and cellulase activity towards broad substrate range potentially explain its wide host range. This is the first study to provide a broad biochemical insight into Cuscuta GH9 cellulases, which based on our study may have potential applications in industrial bioprocessing.

Genome-wide characterization of post-transcriptional processes related to wood formation in Dalbergia odorifera

BackgroundAlternative polyadenylation (APA), alternative splicing (AS), and long non-coding RNAs (lncRNAs) play regulatory roles in post-transcriptional processes in plants. However, little is known about their involvement in xylem development in Dalbergia odorifera, a valuable rosewood species with medicinal and commercial significance. We addressed this by conducting Isoform Sequencing (Iso-Seq) using PacBio’s SMRT technology and combined it with RNA-seq analysis (RNA sequencing on Illumina platform) after collecting xylem samples from the transition zone and the sapwood of D. odorifera.ResultsWe identified 14,938 full-length transcripts, including 9,830 novel isoforms, which has updated the D. odorifera genome annotation. Our analysis has revealed that 4,164 genes undergo APA, whereas 3,084 genes encounter AS. We have also annotated 118 lncRNAs. Furthermore, RNA-seq analysis identified 170 differential alternative splicing (DAS) events, 344 genes with differential APA site usage (DE-APA), and 6 differentially expressed lncRNAs in the transition zone when compared to the sapwood. AS, APA, and lncRNAs are differentially regulated during xylem development. Differentially expressed APA genes were enriched for terpenoid and flavonoid metabolism, indicating their role in the heartwood formation. Additionally, DE-APA genes were associated with cell wall biosynthesis and terpenoid metabolism, implying an APA’s role in wood formation. A DAS gene (involved in chalcone accumulation) with a significantly greater inclusion of the last exon in the transition zone than in the sapwood was identified. We also found that differentially expressed lncRNAs targeted the genes related to terpene synthesis.ConclusionsThis study enhances our understanding of the molecular regulatory mechanisms underlying wood formation in D. odorifera, and provides valuable genetic resources and insights for its molecular-assisted breeding.

Precocious cell differentiation occurs in proliferating cells in leaf primordia in Arabidopsis angustifolia3 mutant.

During leaf development, the timing of transition from cell proliferation to expansion is an important factor in determining the final organ size. However, the regulatory system involved in this transition remains less understood. To get an insight into this system, we investigated the compensation phenomenon, in which the cell number decreases while the cell size increases in organs with determinate growth. Compensation is observed in several plant species suggesting coordination between cell proliferation and expansion. In this study, we examined an Arabidopsis mutant of ANGUSTIFOLIA 3 (AN3)/GRF-INTERACTING FACTOR 1, a positive regulator of cell proliferation, which exhibits the compensation. Though the AN3 role has been extensively investigated, the mechanism underlying excess cell expansion in the an3 mutant remains unknown. Focusing on the early stage of leaf development, we performed kinematic, cytological, biochemical, and transcriptome analyses, and found that the cell size had already increased during the proliferation phase, with active cell proliferation in the an3 mutant. Moreover, at this stage, chloroplasts, vacuoles, and xylem cells developed earlier than in the wild-type cells. Transcriptome data showed that photosynthetic activity and secondary cell wall biosynthesis were activated in an3 proliferating cells. These results indicated that precocious cell differentiation occurs in an3 cells. Therefore, we suggest a novel AN3 role in the suppression of cell expansion/differentiation during the cell proliferation phase.

Bactericidal and biofilm eradication efficacy of a fluorinated benzimidazole derivative, TFBZ, against methicillin-resistant Staphylococcus aureus.

Methicillin-resistant Staphylococcus aureus (MRSA) is a major inducement of nosocomial infections and its biofilm formation render the high tolerance to conventional antibiotics, which highlights the requirement to develop new antimicrobial agents urgently. In this study, we identified a fluorinated benzimidazole derivative, TFBZ, with potent antibacterial efficacy toward planktonic MRSA (MIC = 4μg/mL, MBC = 8μg/mL) and its persistent biofilms (≥99%, MBEC = 8μg/mL). TFBZ manifested significant irreversible time-dependent killing against MRSA as characterized by diminished cell viability, bacterial morphological change and protein leakage. Furthermore, the results from CBD devices, crystal violet assay in conjunction with live/dead staining and scanning electron microscopy confirmed that TFBZ was capable of eradicating preformed MRSA biofilms with high efficiency. Simultaneously, TFBZ reduced the bacterial invasiveness and exerted negligible hemolysis and cytotoxicity toward mammalian cells, which ensuring the robust therapeutic effect on mouse skin abscess model. The transcriptome profiling and quantitative RT-PCR revealed that a set of encoding genes associated with cell adhesion, biofilm formation, translation process, cell wall biosynthesis was consistently downregulated in MRSA biofilms upon exposure to TFBZ. In conclusion, TFBZ holds promise as a valuable candidate for therapeutic applications against MRSA chronic infections.

Synthesis, and molecular docking of thiourea derivatives as antibacterial agents targeting enzymes involved in biosynthesis of bacterial cell wall

Background: New antibacterials are needed due to the increasing resistance of bacteria to existing antibiotics. Thiourea derivative compounds (benzoylthiourea and 1,3-dibenzoylthiourea) contain aromatic groups, thio groups (C=S), and amide groups (H2N-C=O), which are commonly found in the class of antibacterial drugs. Molecular docking can be used to predict their antibacterial activity.     Objective: This study aimed to synthesise thiourea derivatives and predict their antibacterial activity by in silico method.     Methods: Synthesis was performed using nucleophilic substitution reactions. The synthesised compounds were identified using UV-Vis, FT-IR, and 1H-NMR. Molecular docking was conducted using the MOE program ver 2022.02.    Results: Benzoylthiourea (BTU) and 1,3-dibenzoylthiourea (DBTU) compounds were obtained with yields of 36.55% and 12.68%, respectively. The melting point 171-173°C for BTU and 202-204°C for DBTU. Molecular docking results showed higher binding affinity of DBTU against PBP2a (docking score < -5.75 kcal/mol) and FaBH (docking score <-4.7935 kcal/mol) compared to the corresponding native ligands, while the two compounds had lower affinity for the muramyl ligase.     Conclusion: BTU and DBTU can be synthesised by nucleophilic substitution reactions. DBTU is predicted to exhibit antibacterial activity against Methicilin Resistant Staphylococcus aureus (MRSA) and Mycobacterium tuberculosis.

Unveiling the intricacies of allosteric regulation in aspartate kinase from the Wolbachia endosymbiont of Brugia Malayi: Mechanistic and therapeutic insights

Aspartate kinase (AK), an enzyme from the Wolbachia endosymbiont of Brugia malayi (WBm), plays a pivotal role in the bacterial cell wall and amino acid biosynthesis, rendering it an attractive candidate for therapeutic intervention. Allosteric inhibition of aspartate kinase is a prevalent mode of regulation across microorganisms and plants, often modulated by end products such as lysine, threonine, methionine, or meso-diaminopimelate. The intricate and diverse nature of microbial allosteric regulation underscores the need for rigorous investigation. This study employs a combined experimental and computational approach to decipher the allosteric regulation of WBmAK. Molecular Dynamics (MD) simulations elucidate that ATP (cofactor) and ASP (substrate) binding induce a closed conformation, promoting enzymatic activity. In contrast, the binding of lysine (allosteric inhibitor) leads to enzyme inactivation and an open conformation. The enzymatic assay demonstrates the optimal activity of WBmAK at 28 °C and a pH of 8.0. Notably, the allosteric inhibition study highlights lysine as a more potent inhibitor compared to threonine. Importantly, this investigation sheds light on the allosteric mechanism governing WBmAK and imparts novel insights into structure-based drug discovery, paving the way for the development of effective inhibitors against filarial pathogens.

In silico characterization of a MYB TF (WsMYB46) from the medicinal plant Withania somnifera L. predicting its probable role in secondary cell wall biosynthesis

In silico characterization of a MYB TF (WsMYB46) from the medicinal plant Withania somnifera L. predicting its probable role in secondary cell wall biosynthesis

Physiological and transcriptomic comparisons shed light on the cold stress response mechanisms of Dendrobium spp.

Dendrobium spp. comprise a group of tropical orchids with ornamental and medicinal value. Dendrobium spp. are sensitive to low temperature, and the underlying cold response regulatory mechanisms in this group are unclear. To understand how these plants respond to cold stress, we compared the transcriptomic responses of the cold-tolerant cultivar 'Hongxing' (HX) and the cold-sensitive cultivar 'Sonia Hiasakul' (SH) to cold stress. Chemometric results showed that the physiological response of SH in the later stages of cold stress is similar to that of HX throughout the cold treatment. Orthogonal partial least squares discriminant analysis (OPLS-DA) revealed that soluble protein content and peroxidase activity are key physiological parameters for assessing the cold tolerance of these two Dendrobium spp. cultivars. Additionally, weighted gene co-expression network analysis (WGCNA) results showed that many cold response genes and metabolic pathways significantly associated with the physiological indices were enriched in the 12 detected modules. The Kyoto Encyclopedia of Genes and Genomes (KEGG) and gene ontology (GO) enrichment analyses of the 105 hub genes showed that Dendrobium spp. adapt to cold stress by regulating signal transduction, phytohormones, transcription factors, protein translation and modification, functional proteins, biosynthesis and metabolism, cell structure, light, and the circadian clock. Hub genes of the cold stress response network included the remorin gene pp34, the abscisic acid signaling pathway-related genes PROTEIN PHOSPATASE 2C (PP2C), SNF1-RELATED PROTEIN KINASE 2 (SnRK2), ABRE-BINDING FACTOR 1 (ABF1) and SKI-INTERACTING PROTEIN 17 (SKIP17), the Ca2+ signaling-related GTP diphosphokinase gene CRSH1, the carbohydrate-related gene STARCH SYNTHASE 2 (SS2), the cell wall biosynthesis gene CINNAMYL ALCOHOL DEHYDROGENASE (CAD7), and the endocytosis-related gene VACUOLAR PROTEIN SORTING-ASSOCIATED PROTEIN 52A (VPS52A). The cold-responsive genes and metabolic pathways of Dendrobium spp. revealed in this study provide important insight to enable the genetic enhancement of cold tolerance in Dendrobium spp., and to facilitate cold tolerance breeding in related plants.

A Fluorous Peptide Amphiphile with Potent Antimicrobial Activity for the Treatment of MRSA-induced Sepsis and Chronic Wound Infection.

The rising prevalence of global antibiotic resistance evokes the urgent need for novel antimicrobial candidates. Cationic lipopeptides have attracted much attention due to their strong antimicrobial activity, broad-spectrum and low resistance tendency. Herein, a library of fluoro-lipopeptide amphiphiles was synthesized by tagging a series of cationic oligopeptides with a fluoroalkyl tail via a disulfide spacer. Among the lipopeptide candidates, R6F bearing six arginine moieties and a fluorous tag shows the highest antibacterial activity, and it exhibits an interesting fluorine effect as compared to the non-fluorinated lipopeptides. The high antibacterial activity of R6F is attributed to its excellent bacterial membrane permeability, which further disrupts the respiratory chain redox stress and cell wall biosynthesis of the bacteria. By co-assembling with lipid nanoparticles, R6F showed high therapeutic efficacy and minimal adverse effects in the treatment of MRSA-induced sepsis and chronic wound infection. This work provides a novel strategy to design highly potent antibacterial peptide amphiphiles for the treatment of drug-resistant bacterial infections.

Role of UDP-N-acetylmuramic acid in the regulation of MurA activity revealed by molecular dynamics simulations.

The peptidoglycan biosynthesis pathway plays a vital role in bacterial cells, and facilitates peptidoglycan layer formation, a fundamental structural component of the bacterial cell wall. The enzymes in this pathway are candidates for antibiotic development, as most do not have mammalian homologues. The UDP-N-acetylglucosamine (UNAG) enolpyruvyl transferase enzyme (MurA) in the peptidoglycan pathway cytoplasmic step is responsible for the phosphoenolpyruvate (PEP)-UNAG catalytic reaction, forming UNAG enolpyruvate and inorganic phosphate. Reportedly, UDP-N-acetylmuramic acid (UNAM) binds tightly to MurA forming a dormant UNAM-PEP-MurA complex and acting as a MurA feedback inhibitor. MurA inhibitors are complex, owing to competitive binding interactions with PEP, UNAM, and UNAG at the MurA active site. We used computational methods to explore UNAM and UNAG binding. UNAM showed stronger hydrogen-bond interactions with the Arg120 and Arg91 residues, which help to stabilize the closed conformation of MurA, than UNAG. Binding free energy calculations using end-point computational methods showed that UNAM has a higher binding affinity than UNAG, when PEP is attached to Cys115. The unbinding process, simulated using τ-random acceleration molecular dynamics, showed that UNAM has a longer relative residence time than UNAG, which is related to several complex dissociation pathways, each with multiple intermediate metastable states. This prevents the loop from opening and exposing the Arg120 residue to accommodate UNAG and potential new ligands. Moreover, we demonstrate the importance of Cys115-linked PEP in closed-state loop stabilization. We provide a basis for evaluating novel UNAM analogues as potential MurA inhibitors. PUBLIC SIGNIFICANCE: MurA is a critical enzyme involved in bacterial cell wall biosynthesis and is involved in antibiotic resistance development. UNAM can remain in the target protein's active site for an extended time compared to its natural substrate, UNAG. The prolonged interaction of this highly stable complex known as the 'dormant complex' comprises UNAM-PEP-MurA and offers insights into antibiotic development, providing potential options against drug-resistant bacteria and advancing our understanding of microbial biology.

Synergistic antifungal mechanism of cinnamaldehyde and nonanal against Aspergillus flavus and its application in food preservation

Aspergillus flavus colonization on agricultural products during preharvest and postharvest results in tremendous economic losses. Inspired by the synergistic antifungal effects of essential oils, the aims of this study were to explore the mechanism of combined cinnamaldehyde and nonanal (SCAN) against A. flavus and to evaluate the antifungal activity of SCAN loading into diatomite (DM). Shriveled mycelia were observed by scanning electron microscopy, especially in the SCAN treatment group. Calcofluor white staining, transmission electron microscopy, dichloro-dihydro-fluorescein diacetate staining and the inhibition of key enzymes in tricarboxylic acid cycle indicated that the antifungal mechanism of SCAN against A. flavus was related to the cell wall damage, reactive oxygen species accumulation and energy metabolism interruption. RNA sequencing revealed that some genes involved in antioxidation were upregulated, whereas genes responsible for cell wall biosynthesis, oxidative stress, cell cycle and spore development were significantly downregulated, supporting the occurrence of cellular apoptosis. In addition, compared with the control group, conidia production in 1.5 mg/mL DM/cinnamaldehyde, DM/nonanal and DM/SCAN groups were decreased by 27.16%, 48.22% and 76.66%, respectively, and the aflatoxin B1 (AFB1) contents decreased by 2.00%, 73.02% and 84.15%, respectively. These finding suggest that DM/SCAN complex has potential uses in food preservation.

Targeting MurB from Helicobacter pylori: insights from virtual screening, molecular docking and molecular dynamics simulation

ABSTRACT Helicobacter pylori is a gram-negative, helical-shaped bacteria found in the mucus lining of the stomach of humans responsible for causing sores or an ulcer. H. pylori is becoming a multi-drug resistant bacterium, which in turn demands the need for development of alternative treatment strategies for the proper management of diseases. The peptidoglycan biosynthesis pathway is critical for the synthesis of cell walls and for the survival of H. pylori. There are several crucial enzymes in this biosynthesis pathway which can act as significant drug targets against H. pylori. One of these important enzymes is UDP-N-acetylenolpyruvoylglucosamine reductase (MurB), which catalyses an important committed step of cell wall biosynthesis. In the present study, we performed a high throughput virtual screening using the Enamine HTSC library against the MurB enzyme. The molecules were also screened for druglike properties by ADME screening, toxicity, and tumorigenic nature, followed by MD simulations. We found that Z102621114_1 and Z228235240_1 ligand molecules can act as potential inhibitors of MurB protein. Our results suggest, these molecules may be able to meet the demand for novel antimicrobials to treat H. pylori medication resistance. The subsequent experimental investigations can increase their potential as a novel agents against H. pylori infections. Research highlights Helicobacter pylori infects 50% of the Global population. Helicobacter pylori infection is associated with gastric cancer. MurB is a key drug target protein as it is responsible for cell wall synthesis. Z102621114_1 and Z228235240_1 were identified as potential inhibitors of MurB of Helicobacter pylori.

Integrated Transcriptomic and Proteomic Characterization of a Chromosome Segment Substitution Line Reveals the Regulatory Mechanism Controlling the Seed Weight in Soybean

Soybean is the major global source of edible oils and vegetable proteins. Seed size and weight are crucial traits determining the soybean yield. Understanding the molecular regulatory mechanism underlying the seed weight and size is helpful for improving soybean genetic breeding. The molecular regulatory pathways controlling the seed weight and size were investigated in this study. The 100-seed weight, seed length, seed width, and seed weight per plant of a chromosome segment substitution line (CSSL) R217 increased compared with those of its recurrent parent ‘Suinong14’ (SN14). Transcriptomic and proteomic analyses of R217 and SN14 were performed at the seed developmental stages S15 and S20. In total, 2643 differentially expressed genes (DEGs) and 208 differentially accumulated proteins (DAPs) were detected at S15, and 1943 DEGs and 1248 DAPs were detected at S20. Furthermore, integrated transcriptomic and proteomic analyses revealed that mitogen-activated protein kinase signaling and cell wall biosynthesis and modification were potential pathways associated with seed weight and size control. Finally, 59 candidate genes that might control seed weight and size were identified. Among them, 25 genes were located on the substituted segments of R217. Two critical pathways controlling seed weight were uncovered in our work. These findings provided new insights into the seed weight-related regulatory network in soybean.

Quantitative Shotgun Proteomic Analysis of Bacteria after Overexpression of Recombinant Spider Miniature Spidroin, MaSp1.

Spider silk has extraordinary mechanical properties, displaying high tensile strength, elasticity, and toughness. Given the high performance of natural fibers, one of the long-term goals of the silk community is to manufacture large-scale synthetic spider silk. This process requires vast quantities of recombinant proteins for wet-spinning applications. Attempts to synthesize large amounts of native size recombinant spidroins in diverse cell types have been unsuccessful. In these studies, we design and express recombinant miniature black widow MaSp1 spidroins in bacteria that incorporate the N-terminal and C-terminal domain (NTD and CTD), along with varying numbers of codon-optimized internal block repeats. Following spidroin overexpression, we perform quantitative analysis of the bacterial proteome to identify proteins associated with spidroin synthesis. Liquid chromatography with tandem mass spectrometry (LC MS/MS) reveals a list of molecular targets that are differentially expressed after enforced mini-spidroin production. This list included proteins involved in energy management, proteostasis, translation, cell wall biosynthesis, and oxidative stress. Taken together, the purpose of this study was to identify genes within the genome of Escherichia coli for molecular targeting to overcome bottlenecks that throttle spidroin overexpression in microorganisms.

Reducing nitrogen application at high planting density enhances secondary cell wall formation and decreases stem lodging in rapeseed

Reducing the rate of nitrogen fertilizer (N rate) and achieving high plant density is an effective and economically beneficial approach to enhance rapeseed productivity. However, it is unclear how N rate affects stem lodging in rapeseed directly-sown at high densities. In this study, the effect of different N rates on stem lodging at high plant density was examined in field trial and pot experiments using two modern hybrid rapeseed varieties, Fengyou520 (FY520) and Huayouza62 (HYZ62). Increasing N fertilizer from low level to adequate level significantly increased yield by 39% in FY520 and 43% in HYZ62. However, with elevated N yield increases were limited by an increase in stem lodging. At T1 (the first inflorescence branch below the apex has the first flowers open) phloroglucinol-HCl staining for lignin was weaker under high N (N4: 4 g N pot−1) compared with adequate N (N2: 2 g N pot−1), and was correlated with weaker stem strength. Differences in stem lignin were also associated with variations in gene expression as revealed by transcriptomic profiling of middle stems at T1. Differentially expressed genes indicated significant enrichment for cell wall. Several genes encoding known transcriptional regulators of secondary cell walls (SCWs) biosynthesis and deposition were down-regulated with high N compared with adequate N. Many genes putatively involved in lignin biosynthesis, cellulose biosynthesis and assembly and xylan biosynthesis are down-regulated with high N, corresponding to lower accumulation of lignin, cellulose and hemicellulose in these plants. These findings not only provide us with gene candidates potentially affecting stem lodging in direct sown rapeseed, but also reveal that reducing N at high plant density enhances biosynthesis of stem cell walls to alleviate stem lodging.

Antifungal activity of a maleimide derivative: disruption of cell membranes and interference with iron ion homoeostasis

ABSTRACT Fungal infections caused by Candida albicans have posed a persistent threat to human health. Existing clinical antifungal drugs are constrained by issues such as drug resistance and side effects. Compounds containing maleimide rings have been verified to possess antifungal properties, although the specific molecular mechanisms by which they exert this activity have yet to be fully understood. A total of 40 compounds containing maleimide rings were synthesised in the present study, and 12 derivatives that possessed antifungal properties were subsequently identified. The maleimide compound 5 (MPD) with the most potent activity demonstrated fungicidal action at a concentration that was twice as potent as the minimal inhibitory concentration and effectively prevented the formation of biofilms. Furthermore, the mechanistic studies revealed that MPD interfered with iron ion homoeostasis by reducing intracellular iron concentration inside cells, which led to the inhibition of ergosterol biosynthesis and increased cell membrane permeability, resulting in the leakage of intracellular trehalose. In addition, MPD was observed to perturb cell wall biosynthesis by reducing the activity of chitin synthase. Moreover, MPD was found to demonstrate therapeutical efficacy in vivo when assessed using a Caenorhabditis elegans-C. albicans infection model.

Reciprocal regulation of enterococcal cephalosporin resistance by products of the autoregulated yvcJ-glmR-yvcL operon enhances fitness during cephalosporin exposure.

Enterococci are commensal members of the gastrointestinal tract and also major nosocomial pathogens. They possess both intrinsic and acquired resistance to many antibiotics, including intrinsic resistance to cephalosporins that target bacterial cell wall synthesis. These antimicrobial resistance traits make enterococcal infections challenging to treat. Moreover, prior therapy with antibiotics, including broad-spectrum cephalosporins, promotes enterococcal proliferation in the gut, resulting in dissemination to other sites of the body and subsequent infection. As a result, a better understanding of mechanisms of cephalosporin resistance is needed to enable development of new therapies to treat or prevent enterococcal infections. We previously reported that flow of metabolites through the peptidoglycan biosynthesis pathway is one determinant of enterococcal cephalosporin resistance. One factor that has been implicated in regulating flow of metabolites into cell wall biosynthesis pathways of other Gram-positive bacteria is GlmR. In enterococci, GlmR is encoded as the middle gene of a predicted 3-gene operon along with YvcJ and YvcL, whose functions are poorly understood. Here we use genetics and biochemistry to investigate the function of the enterococcal yvcJ-glmR-yvcL gene cluster. Our results reveal that YvcL is a DNA-binding protein that regulates expression of the yvcJ-glmR-yvcL operon in response to cell wall stress. YvcJ and GlmR bind UDP-GlcNAc and reciprocally regulate cephalosporin resistance in E. faecalis, and binding of UDP-GlcNAc by YvcJ appears essential for its activity. Reciprocal regulation by YvcJ/GlmR is essential for fitness during exposure to cephalosporin stress. Additionally, our results indicate that enterococcal GlmR likely acts by a different mechanism than the previously studied GlmR of Bacillus subtilis, suggesting that the YvcJ/GlmR regulatory module has evolved unique targets in different species of bacteria.

Repurposing of Compounds from Streptomyces spp. as Potential Inhibitors of Aminoacyltransferase FemA: An Essential Drug Target against Drug-resistant Staphylococcus aureus.

Drug-resistant Staphylococcus aureus represents a substantial healthcare challenge worldwide, and its range of available therapeutic options continues to diminish progressively. Thus, this study aimed to identify potential inhibitors against FemA, a crucial protein involved in the cell wall biosynthesis of S. aureus. The screening process involved a comprehensive structure-based virtual screening on the StreptomDB database to identify ligands with potential inhibitory effects on FemA using AutoDock Vina. The most desirable ligands with the highest binding affinity and pharmacokinetic properties were selected. Two ligands with the highest number of hydrogen bonds and hydrophobic interactions were further analyzed by molecular dynamics (MD) using the GROMACS version 2018 simulation package. Six H-donor conserved residues were selected as protein active sites, including Arg- 220, Tyr-38, Gln-154, Asn-73, Arg-74, and Thr-24. Through virtual screening, a total of nine compounds with the highest binding affinity to the FemA protein were identified. Frigocyclinone and C21H21N3O4 exhibited the highest binding affinity and demonstrated favorable pharmacokinetic properties. Molecular dynamics analysis of the FemA-ligand complexes further indicated desirable stability and reliability of complexes, reinforcing the potential efficacy of these ligands as inhibitors of FemA protein. Our findings suggest that Frigocyclinone and C21H21N3O4 are promising inhibitors of FemA in S. aureus. To further validate these computational results, experimental studies are planned to confirm the inhibitory effects of these compounds on various S. aureus strains. Combining computational screening with experimental validation contributes valuable insights to the field of drug discovery in comparison to the classical drug discovery approaches.

Characterization of ZmCesAs for Secondary Cell Wall Biosynthesis in Maize

Characterization of ZmCesAs for Secondary Cell Wall Biosynthesis in Maize