A key bacterial cytoskeletal cell division protein FtsZ as a novel therapeutic antibacterial drug target

Proteomic approach to identify host cell attachment proteins provides protective Pseudomonas aeruginosa vaccine antigen FtsZ

Pseudomonas aeruginosa is an opportunistic Gram-negative pathogen that causes severe nosocomial infections in susceptible individuals due to the emergence of multidrug-resistant strains. There are no approved vaccines against P. aeruginosa infections nor candidates in active clinical development, highlighting the need for novel candidates and strategies. Using a cell-blot proteomic approach, we reproducibly identified 49 proteins involved in interactions with human lung epithelial cells across four P. aeruginosa strains. Among these were cell division protein FtsZ and outer membrane protein OpmH. Escherichia coli BL21 cells overexpressing recombinant FtsZ or rOpmH showed a 66- and 15-fold increased ability to attach to 16HBE14o- cells, further supporting their involvement in host cell attachment. Both antigens led to proliferation of NK and CD8+ cytotoxic T cells, significant increases in the production of IFN-γ, IL-17A, TNF and IL-4 in immunised mice and elicited strong antigen-specific serological IgG1 and IgG2c responses. Immunisation with FtsZ significantly reduced bacterial burden in the lungs by 1.9-log CFU and dissemination to spleen by 1.8-log CFU. The protective antigen candidate, FtsZ, would not have been identified by traditional approaches relying on either virulence mechanisms or sequence-based predictions, opening new avenues in the development of an anti-P. aeruginosa vaccine.

Curcumin-loaded scaffolds in bone regeneration

In recent years, there has been a notable surge in the development of engineered bone scaffolds intended for the repair of bone defects. While autografts and allografts have traditionally served as the primary methods in bone tissue engineering, their inherent limitations have spurred the exploration of novel avenues in biomedical implant development. The emergence of bone scaffolds not only facilitates bone reconstruction but also offers a platform for the targeted delivery of therapeutic agents. There exists a pervasive interest in leveraging various drugs, proteins, growth factors, and biomolecules with osteogenic properties to augment bone formation, as the enduring side effects associated with current clinical modalities necessitate the pursuit of safer alternatives. Curcumin, the principal bioactive compound found in turmeric, has demonstrated notable efficacy in regulating the proliferation and differentiation of bone cells while promoting bone formation. Nevertheless, its utility is hindered by restricted water solubility and poor bioavailability. Strategies aimed at enhancing the solubility, stability, and bioavailability of curcumin, including formulation techniques such as liposomes and nanoparticles or its complexation with metals, have been explored. This investigation is dedicated to exploring the impact of curcumin on the proliferation, differentiation, and migration of osteocytes, osteoblasts, and osteoclasts.

iTRAQ-based quantitative proteomic analysis of the antibacterial mechanism of silver nanoparticles against multidrug-resistant Streptococcus suis

Background

The increase in antibiotic resistance of bacteria has become a major concern in clinical treatment. Silver nanoparticles (AgNPs) have significant antibacterial effects against Streptococcus suis. Therefore, this study aimed to investigate the antibacterial activity and mechanism of action of AgNPs against multidrug-resistant S. suis.

Methods

The effect of AgNPs on the morphology of multidrug-resistant S. suis was observed using scanning electron microscopy (SEM). Differentially expressed proteins were analyzed by iTRAQ quantitative proteomics, and the production of reactive oxygen species (ROS) was assayed by H2DCF-DA staining.

Results

SEM showed that AgNPs disrupted the normal morphology of multidrug-resistant S. suis and the integrity of the biofilm structure. Quantitative proteomic analysis revealed that a large number of cell wall synthesis-related proteins, such as penicillin-binding protein and some cell cycle proteins, such as the cell division protein FtsZ and chromosomal replication initiator protein DnaA, were downregulated after treatment with 25 μg/mL AgNPs. Significant changes were also observed in the expression of the antioxidant enzymes glutathione reductase, alkyl hydroperoxides-like protein, α/β superfamily hydrolases/acyltransferases, and glutathione disulfide reductases. ROS production in S. suis positively correlated with AgNP concentration.

Conclusion

The potential antibacterial mechanism of AgNPs may involve disrupting the normal morphology of bacteria by inhibiting the synthesis of cell wall peptidoglycans and inhibiting the growth of bacteria by inhibiting the cell division protein FtsZ and Chromosomal replication initiator protein DnaA. High oxidative stress may be a significant cause of bacterial death. The potential mechanism by which AgNPs inhibit S. suis biofilm formation may involve affecting bacterial adhesion and interfering with the quorum sensing system.

Comparative molecular docking and toxicity between carbon-capped metal oxide nanoparticles and standard drugs in cancer and bacterial infections

Introduction

Nanoparticles (NPs) are of great interest in the design of various drugs due to their high surface-to-volume ratio, which result from their unique physicochemical properties. Because of the importance of examining the interactions between newly designed particles with different targets in the case of various diseases, techniques for examining the interactions between these particles with different targets, many of which are proteins, are now very common.

Methods

In this study, the interactions between metal oxide nanoparticles (MONPs) covered with a carbon layer (Ag2O3, CdO, CuO, Fe2O3, FeO, MgO, MnO, and ZnO NPs) and standard drugs related to the targets of Cancer and bacterial infections were investigated using the molecular docking technique with AutoDock 4.2.6 software tool. Finally, the PRO TOX-II online tool was used to compare the toxicity (LD50) and molecular weight of these MONPs to standard drugs.

Results

According to the data obtained from the semi flexible molecular docking process, MgO and Fe2O3 NPs performed better than standard drugs in several cases. MONPs typically have a lower 50% lethal dose (LD50) and a higher molecular weight than standard drugs. MONPs have shown a minor difference in binding energy for different targets in three diseases, which probably can be attributed to the specific physicochemical and pharmacophoric properties of MONPs.

Conclusion

The toxicity of MONPs is one of the major challenges in the development of drugs based on them. According to the results of these molecular docking studies, MgO and Fe2O3 NPs had the highest efficiency among the investigated MONPs.

Investigating the Antituberculosis Activity of Selected Commercial Essential Oils and Identification of Active Constituents Using a Biochemometrics Approach and In Silico Modeling

Tuberculosis (TB) is a disease caused by Mycobacterium tuberculosis which has become prevalent due to the emergence of resistant M. tuberculosis strains. The use of essential oils (EOs) as potential anti-infective agents to treat microbial infections, including TB, offers promise due to their long historical use and low adverse effects. The current study aimed to investigate the in vitro anti-TB activity of 85 commercial EOs, and identify compounds responsible for the activity, using a biochemometrics approach. A microdilution assay was used to determine the antimycobacterial activity of the EOs towards some non-pathogenic Mycobacterium strains. In parallel, an Alamar blue assay was used to investigate antimycobacterial activity towards the pathogenic M. tuberculosis strain. Chemical profiling of the EOs was performed using gas chromatography-mass spectrometry (GC-MS) analysis. Biochemometrics filtered out putative biomarkers using orthogonal projections to latent structures discriminant analysis (OPLS-DA). In silico modeling was performed to identify potential therapeutic targets of the active biomarkers. Broad-spectrum antimycobacterial activity was observed for Cinnamomum zeylanicum (bark) (MICs = 1.00, 0.50, 0.25 and 0.008 mg/mL) and Levisticum officinale (MICs = 0.50, 0.5, 0.5 and 0.004 mg/mL) towards M. smegmatis, M. fortuitum, M. gordonae and M. tuberculosis, respectively. Biochemometrics predicted cinnamaldehyde, thymol and eugenol as putative biomarkers. Molecular docking demonstrated that cinnamaldehyde could serve as a scaffold for developing a novel class of antimicrobial compounds by targeting FtsZ and PknB from M. tuberculosis.

Filamentous Thermosensitive Mutant Z: An Appealing Target for Emerging Pathogens and a Trek on Its Natural Inhibitors

Antibiotic resistance is a major emerging issue in the health care sector, as highlighted by the WHO. Filamentous Thermosensitive mutant Z (Fts-Z) is gaining significant attention in the scientific community as a potential anti-bacterial target for fighting antibiotic resistance among several pathogenic bacteria. The Fts-Z plays a key role in bacterial cell division by allowing Z ring formation. Several in vitro and in silico experiments have demonstrated that inhibition of Fts-Z can lead to filamentous growth of the cells, and finally, cell death occurs. Many natural compounds that have successfully inhibited Fts-Z are also studied. This review article intended to highlight the structural-functional aspect of Fts-Z that leads to Z-ring formation and its contribution to the biochemistry and physiology of cells. The current trend of natural inhibitors of Fts-Z protein is also covered.

Natural Antibacterial and Antivirulence Alkaloids From Macleaya cordata Against Methicillin-Resistant Staphylococcus aureus

The emergence and spread of antibiotic-resistant bacteria, such as methicillin-resistant Staphylococcus aureus (MRSA), underly the urgent need to develop novel antibacterial drugs. Macleaya cordata, a traditional medicinal plant, has been widely used in livestock animals, plants, and humans. Alkaloids are the primary bioactive compounds of Macleaya cordata and exhibit antibacterial, antiinflammatory, and antioxidant activities. Nevertheless, the antibacterial compounds and mode of action of Macleaya cordata remain unclear. In the present study, we investigated the antibacterial activity and mode of action of alkaloids from Macleaya cordata. Sanguinarine, 6-ethoxysanguinarine (6-ES), 6-methoxydihydrosanguinarine (6-MS), chelerythrine (CH), and dihydrochelerythrine (DICH) exhibited good antibacterial activity against Gram-positive bacteria, including MRSA. 6-ES rapidly killed MRSA, possibly by interfering with membrane and metabolic functions including ROS production by targeting the membrane and FtsZ in S. aureus. Additionally, 6-ES directly suppressed the hemolytic activity of α-hemolysin, alleviated inflammatory responses, and eliminated intracellular MRSA, as well as displayed low development of drug resistance, in vitro. Finally, a 6-ES-loaded thermosensitive hydrogel promoted wound healing in mice infected with MRSA. These results supported 6-ES as a novel potential candidate or leading compound with antibacterial, antivirulence, and host immunomodulatory activities in fighting against bacterial infections.

Host-directed antimycobacterial activity of colchicine, an anti-gout drug, via strengthened host innate resistance reinforced by the IL-1β/PGE2 axis

BACKGROUND AND PURPOSE

To diversify and expand possible tuberculosis (TB) drug candidates and maximize limited global resources, we investigated the effect of colchicine, an FDA-approved anti-gout drug, against Mycobacterium tuberculosis (Mtb) infection because of its immune-modulating effect.

EXPERIMENTAL APPROACH

We evaluated the intracellular anti-Mtb activity of different concentrations of colchicine in murine bone marrow-derived macrophages (BMDMs). To elucidate the underlying mechanism, RNA sequencing, biological and chemical inhibition assays, and Western blot, quantitative real-time PCR, enzyme-linked immunosorbent assay (ELISA) and immunohistochemical analyses were employed. Finally, type I interferon-dependent highly TB-susceptible A/J mice were challenged with virulent Mtb H37Rv, and the host-directed therapeutic effect of oral colchicine administration on bacterial burdens and lung inflammation was assessed 30 days post-infection (2.5 mg·kg^-1 every two days).

KEY RESULTS

Colchicine reinforced the anti-Mtb activity of BMDMs without affecting cell viability, indicating that colchicine facilitated macrophage immune activation upon Mtb infection. The results from RNA sequencing, NLRP3 knockout BMDM, IL-1 receptor blockade, and immunohistochemistry analyses revealed that this unexpected intracellular anti-Mtb activity of colchicine was mediated through NLRP3-dependent IL-1β signalling and Cox-2-regulated PGE₂ production in macrophages. Consequently, the TB-susceptible A/J mouse model showed remarkable protection, with decreased bacterial loads in both the lungs and spleens of oral colchicine-treated mice, with significantly elevated Cox-2 expression at infection sites.

CONCLUSIONS AND IMPLICATIONS

The repurposing of colchicine against Mtb infection in this study highlights its unique function in macrophages upon Mtb infection and its novel potential use in treating TB as host-directed or adjunctive therapy.

A Novel Z-Ring Associated Protein ZapA-Like Protein (PA5407) From Pseudomonas aeruginosa Promotes FtsZ to Form Double Filaments

Bacterial cell division is initiated by the assembly of the contraction ring (Z-ring), which consists of the self-assembled FtsZ protofilaments and dozens of other associate proteins. ZapA, a regulatory protein found in almost all bacteria, stabilizes FtsZ protofilaments to form bundles and enhances the Z-ring condensation. Here, we reported that another small protein from Pseudomonas aeruginosa, ZapA-Like protein (ZapAL; PA5407), is a new FtsZ associated protein. ZapAL exists in many Pseudomonas species and shares only 20% sequence identity to ZapA. ZapAL interacts with FtsZ and induces FtsZ to form long straight double filaments; in comparison, ZapA promotes long bundles with multiple FtsZ filaments. ZapAL has only a mild effect on GTPase activity of FtsZ, which is reduced by around 26% when 10 μM ZapAL is added in the solution. However, to study their assembly dynamics using light-scattering assay, we found that FtsZ-ZapAL double filament is stable and no depolymerization process is observed, which is different from ZapA. Further research found that ZapA and ZapL are likely to form heterodimers. The bundles formed by the mixture of FtsZ-ZapA-ZapAL will depolymerize after GTP is hydrolyzed. Consistent with ZapAL interaction with FtsZ in vitro, the expression of ZapAL-GFP was observed as a narrow band or spots in the middle of the cells, suggesting that it is a component of bacterial division machinery. Similar to ZapA, ZapAL is also not essential for bacterial cell division. Little changes were observed when zapAL gene was deleted, or overexpressed under normal conditions; however, overexpression of ZapAL caused zapA-deficient cells to grow approximately two times longer, showing a mild bacterial division defect. Although we still do not know the exact physiological roles of ZapAL, our results suggest that ZapAL is a novel Z-ring associate protein, which may work together with ZapA to stabilize the FtsZ protofilament and Z-ring structure.

Antibacterial activity of noscapine analogs

The antibacterial properties of close noscapine analogs have not been previously reported. We used our pDualrep2 double-reporter High Throughput Screening (HTS) platform to identify a series of noscapine derivatives with promising antibacterial activity. The platform is based on RPF (SOS-response/DNA damage) and Katushka2S (inhibition of translation) proteins and simultaneously provides information on antibacterial activity and the mechanism of action of small-molecule compounds against E. coli. The most potent compound exhibited an MIC of 13.5 µM(6.25 µg/ml) and a relatively low cytotoxicity against HEK293 cells (CC₅₀ = 71 µM, selectivity index: ~5.5). Some compounds from this series induced average Katushka2S reporter signals, indicating inhibition of translation machinery in the bacteria; however, these compounds did not attenuate translation in vitro in a luciferase-based translation assay. The most effective compounds did not significantly arrest the mitotic cycle in HEK293 cells, in contrast to the parent compound in a flow cytometry assay. Several molecules showed activity against clinically relevant gram-negative and gram-positive bacterial strains. Compounds from the discovered series can be reasonably regarded as good templates for further development and evaluation.

Research Progress on Antibacterial Activities and Mechanisms of Natural Alkaloids: A Review

Alkaloids are nitrogen-containing heterocyclic compounds typically isolated from plants. They represent one of the most important types of natural products because of their large number and structural diversity and complexity. Based on their chemical core structures, alkaloids are classified as isoquinolines, quinolines, indoles, piperidine alkaloids, etc. In-depth analyses of alkaloids have revealed their antibacterial activities. To date, due to the widespread use of antibiotics, the problem of drug-resistant bacterial infections has been gradually increasing, which severely affects the clinical efficacy of antibacterial therapies and patient safety. Therefore, significant research efforts are focused on alkaloids because they represent a potentially new type of natural antibiotic with a wide antibacterial spectrum, rare adverse reactions, and a low tendency to produce drug resistance. Their main antibacterial mechanisms include inhibition of bacterial cell wall synthesis, change in cell membrane permeability, inhibition of bacterial metabolism, and inhibition of nucleic acid and protein synthesis. This article reviews recent reports about the chemical structures and the antibacterial activities and mechanisms of alkaloids. The purpose is to solve the problem of bacterial resistance and to provide a certain theoretical basis and research ideas for the development of new antibacterial drugs.

FtsZ Interactions and Biomolecular Condensates as Potential Targets for New Antibiotics

FtsZ is an essential and central protein for cell division in most bacteria. Because of its ability to organize into dynamic polymers at the cell membrane and recruit other protein partners to form a “divisome”, FtsZ is a leading target in the quest for new antibacterial compounds. Strategies to potentially arrest the essential and tightly regulated cell division process include perturbing FtsZ’s ability to interact with itself and other divisome proteins. Here, we discuss the available methodologies to screen for and characterize those interactions. In addition to assays that measure protein-ligand interactions in solution, we also discuss the use of minimal membrane systems and cell-like compartments to better approximate the native bacterial cell environment and hence provide a more accurate assessment of a candidate compound’s potential in vivo effect. We particularly focus on ways to measure and inhibit under-explored interactions between FtsZ and partner proteins. Finally, we discuss recent evidence that FtsZ forms biomolecular condensates in vitro, and the potential implications of these assemblies in bacterial resistance to antibiotic treatment.

A New Water-Soluble Bactericidal Agent for the Treatment of Infections Caused by Gram-Positive and Gram-Negative Bacterial Strains

Grapefruit and lemon pectin obtained from the respective waste citrus peels via hydrodynamic cavitation in water only are powerful, broad-scope antimicrobials against Gram-negative and -positive bacteria. Dubbed IntegroPectin, these pectic polymers functionalized with citrus flavonoids and terpenes show superior antimicrobial activity when compared to commercial citrus pectin. Similar to commercial pectin, lemon IntegroPectin determined ca. 3-log reduction in Staphylococcus aureus cells, while an enhanced activity of commercial citrus pectin was detected in the case of Pseudomonas aeruginosa cells with a minimal bactericidal concentration (MBC) of 15 mg mL⁻¹. Although grapefruit and lemon IntegroPectin share equal MBC in the case of P. aeruginosa cells, grapefruit IntegroPectin shows boosted activity upon exposure of S. aureus cells with a 40 mg mL⁻¹ biopolymer concentration affording complete killing of the bacterial cells. Insights into the mechanism of action of these biocompatible antimicrobials and their effect on bacterial cells, at the morphological level, were obtained indirectly through Fourier Transform Infrared spectroscopy and directly through scanning electron microscopy. In the era of antimicrobial resistance, these results are of great societal and sanitary relevance since citrus IntegroPectin biomaterials are also devoid of cytotoxic activity, as already shown for lemon IntegroPectin, opening the route to the development of new medical treatments of polymicrobial infections unlikely to develop drug resistance.