Penicillin Binding Research Articles

Frameshift Mutations in Genes Encoding PBP3 and PBP4 Trigger an Unusual, Extreme β-Lactam Resistance Phenotype in Burkholderia multivorans.

In our curated panel of Burkholderia cepacia complex isolates, Burkholderia multivorans strain AU28442 was unusually highly β-lactam resistant. To explore the molecular mechanisms leading to this phenotype, we performed whole genome sequencing (WGS) and microbiological and biochemical assays. WGS analysis revealed that strain AU28442 produced two β-lactamases, AmpC22 and a novel PenA-like β-lactamase denominated PenA39. Additionally, the strain presented frame-shift mutations in the genes encoding penicillin binding proteins 3 (PBP3) and 4 (PBP4). The antibiotic susceptibilities of the parent AU28442 strain carrying blaPenA39 vs the isogenic E. colistrain producing blaPenA39 were discrepant with ceftazidime MICs of >512 and 1 μg/mL, respectively. Accordingly, PenA39 was found to poorly hydrolyze β-lactams with kcat values of ≤8.8 s-1. An overlay of the crystal structure of PenA39 with PenA1 revealed a shift in the SDN loop in the variant, which may affect the catalytic efficiency of PenA39 toward substrates and inhibitors. Moreover, microscopic examination of AU28442 revealed shortened rod-shaped cells compared to B. multivoransATCC 17616, which carries a full complement of intact PBPs. Further complementation assays confirmed that the loss of PBP3 and PBP4 was the main factor contributing to the high-level β-lactam resistance observed in B. multivoransAU28442. This information allowed us to revert susceptibility by pairing a potent β-lactamase inhibitor with a β-lactam with promiscuous PBP binding. This detailed characterization of B. multivoransprovides an illustration of the myriad ways in which bacteria under antibiotic selection can develop resistance and demonstrates a mechanism to overcome it.

LD-transpeptidation is crucial for fitness and polar growth in Agrobacterium tumefaciens.

Peptidoglycan (PG), a mesh-like structure which is the primary component of the bacterial cell wall, is crucial to maintain cell integrity and shape. While most bacteria rely on penicillin binding proteins (PBPs) for crosslinking, some species also employ LD-transpeptidases (LDTs). Unlike PBPs, the essentiality and biological functions of LDTs remain largely unclear. The Hyphomicrobiales order of the Alphaproteobacteria, known for their polar growth, have PG which is unusually rich in LD-crosslinks, suggesting that LDTs may play a more significant role in PG synthesis in these bacteria. Here, we investigated LDTs in the plant pathogen Agrobacterium tumefaciens and found that LD-transpeptidation, resulting from at least one of 14 putative LDTs present in this bacterium, is essential for its survival. Notably, a mutant lacking a distinctive group of 7 LDTs which are broadly conserved among the Hyphomicrobiales exhibited reduced LD-crosslinking and tethering of PG to outer membrane β-barrel proteins. Consequently, this mutant suffered severe fitness loss and cell shape rounding, underscoring the critical role played by these Hyphomicrobiales-specific LDTs in maintaining cell wall integrity and promoting elongation. Tn-sequencing screens further revealed non-redundant functions for A. tumefaciens LDTs. Specifically, Hyphomicrobiales-specific LDTs exhibited synthetic genetic interactions with division and cell cycle proteins, and a single LDT from another group. Additionally, our findings demonstrate that strains lacking all LDTs except one displayed distinctive phenotypic profiles and genetic interactions. Collectively, our work emphasizes the critical role of LD-crosslinking in A. tumefaciens cell wall integrity and growth and provides insights into the functional specialization of these crosslinking activities.

Probing the interaction mechanisms between three β-lactam antibiotics and penicillin-binding proteins of Escherichia coli by molecular dynamics simulations

The presence of antibiotic residues in the aquatic environments poses great potential risks to the aquatic organisms, and even human health. Elucidating the interaction mechanisms between antibiotics and biomacromolecules is crucial for accurately assessing and preventing their potential risks. Therefore, the toxicity of three beta-lactam antibiotics on Escherichia coli (E. coli) was investigated by using the time-dependent toxicity microplate analysis method in this study. Then, molecular docking and molecular dynamics simulation technologies were used to elucidate the potential molecular interactions between β-lactam antibiotics and penicillin-binding proteins of E. coli, and their correlation with the physical and chemical behaviors observed in the physiological and biochemical experiments. The results show that three antibiotics exert inhibitory effects on E. coli cells by modifying their membrane permeability, and even more severe cell damage including rupture, wrinkling, adhesion, indentation, elongation and size alterations. But, toxic effect of the three antibiotics on E. coli varies, and toxicity order is followed by meropenem > cefoperazone > amoxicillin. Van der Waals forces play a vital role in the molecular interactions between the three antibiotics penicillin binding protein of E. coli and the sequence of binding free energy is consistent with the observed toxicity order. Shape compensation is the principal determinant for the binding of antibiotics to penicillin binding proteins, which pertains to the drug-induced alteration in the three-dimensional conformation of penicillin binding proteins.

Spread of the meningococci group C isolates of the clonal complex 10217 beyond the African meningitis belt

ObjectivesTo monitor the spread of invasive meningococcal disease due to group C of the clonal complex 10217 isolates beyond the sub-Saharan African meningitis belt. MethodsCases were confirmed by real-time polymerase chain reaction in blood or cerebrospinal fluid samples and further characterized by multi-locus sequence typing that defined sequence type and clonal complexes. Sequencing of penA gene (encoding the penicillin-binding protein 2) was also used to predict susceptibility to β-lactams. ResultsBetween July and December 2023, we identified four cases of invasive meningococcal disease among adults, with two fatal cases in Algeria. Three cases were among subjects who recently arrived in Algeria from sub-Saharan African countries and one case was reported in an autochthonal subject. A case was also detected in France in 2018 in a subject who traveled to Cameroon. All five cases were provoked by group C isolates and belonged to the clonal complex cc10217 with identical PorA (P1.21-15,16) and FetA (F1-7) markers. The penA sequencing revealed a wildtype allele that is correlated to susceptibility to β-lactams. ConclusionsOur results suggest that serogroup C isolates belonging to cc10217 are spreading beyond the meningitis belt. The data underscore the need for enhanced surveillance to inform vaccination strategies.

GC-MS profiling of the leaf extract of Garcinia pedunculata, molecular docking, ADME/drug likeness predictions and toxicity analysis

Medicinal plants have long been valued for their efficacy, cultural acceptance and lower side effects. Amidst rising concerns about multidrug-resistant bacteria, there is an increasing push to identify novel plant-based drugs with unique mechanisms of action. Garcinia pedunculata, commonly used as food and traditional medicine among tribal communities in North Eastern India, was investigated for its potential medicinal properties. The study involved analyzing the phytoconstituents of the methanolic leaf extract using GC-MS (Gas Chromatography- Mass Spectrometry), which identified 30 compounds. These compounds were further evaluated through in silico studies, including drug-likeness assessments and molecular docking. Molecular docking results indicated that the compounds strongly interacted with Penicillin Binding Protein 4 (PBP4) of Staphylococcus aureus (S aureus), a well-known drug target. Notably, ethane-1,1-diol dipropanoate demonstrated favorable drug-like properties, meeting four out of five drug filters and exhibiting promising physiochemical characteristics, lipophilicity, solubility and pharmacokinetic profiles with minimal toxicity. This suggests its potential for development into novel antimicrobial formulations. Further research using animal models is underway to validate these findings in vivo.

Rapid Detection of Methicillin Resistant Staphylococcus Aureus (MRSA) Using Electric-Double-Layer (EDL) Field-Effect Transistor (FET) Biosensors

According to the latest statistics and analysis by American researchers based on the data from 195 countries worldwide, it has been found that one person in every five people died due to sepsis. The annual death caused by sepsis reaches up to eleven million people, and the number of deaths from sepsis is even higher than those from cancer. We believe that the detection of MRSA is necessary.Staphylococcus aureus is the most common pathogen of sepsis. Methicillin-resistant Staphylococcus aureus (MRSA) or Multiple-resistant Staphylococcus aureus is a distinct strain of Staphylococcus aureus. It has mecA gene which codes for penicillin binding protein 2a (PBP 2A) that will remain active under beta lactams antibiotics. This gives bacterial the ability to grow under concentrations of beta-lactam antibiotics which leads to MRSA's resistance to almost all the different penicillin-type antibiotics including methicillin and other beta-lactamase-resistant penicillins.To detect MRSA in the shortest possible time, we adopt field-effect transistor (FET) biosensor for the real-time detection of binding reactions between DNA probe and cDNA. We select DNA probe sequence of mecA to be the aptamer and immobilize probe DNA which are complementary to the target cDNA on the sensor. This process allows DNA strands to attach to the gold surface. After that, we detect the binding reaction of DNA probe and cDNA by analyzing electrical response of field-effect transistor (FET). We can observe that the Id current changes after cDNA hybridizes with DNA probe.In conclusion, in our research results, Field-effect transistor (FET) biosensor can detect concentration ranging from 1fM to 1pM. In addition, we can achieve other advantages such as more portable, higher sensitivity, real-time monitoring capability, and lower detection limits. With this rapid detection procedure, we can do early diagnosis and treatment, thus improving the quality of human life. Keywords: FET, EDL, Aptamer, DNA, MRSA Figure 1

Antibacterial activities, PASS prediction and ADME analysis of phytochemicals from Curcubita moschata, Curcubita maxima, and Irvingia gabonensis: insights from in silico studies.

Microbial infection management and treatment are crucial as a result of the prevalent antimicrobial resistance issue. Progressive studies are being carried out on how to develop drugs that can mitigate the resistance trends of these microorganisms. Secondary metabolites of plants can also be employed and accessed for this role, as the current study examines the antibacterial activities of phytochemicals from three (3) plants (Cucubita moschata, Cucubita maxima, and Irvingia gabonesis) through computational approaches. Molecular docking studies were carried out to show the binding affinities of the phytochemicals against two target receptors (DNA gyrase and Penicillin Binding Protein 3). In addition, drug likeness analysis, bioactivity and oral-bioavailability properties, absorption, distribution, metabolism, and excretion (ADME) profiling, as well as prediction of activity spectra for substances (PASS) using online tools like SwissADME, PASS online, AdmetSAR2, and Discovery Studio, were also performed. The results obtained identified isochlorogenic acid and apigenin-7-O-glucoside for DNA gyrase (1KZN) and apigenin-7-O-glucoside for Penicillin Binding Protein 3 (4BJP), which were further subjected to molecular dynamics simulation (MDS) and therefore recommended as the lead compounds.

Molecular motor tug-of-war regulates elongasome cell wall synthesis dynamics in Bacillus subtilis

Most rod-shaped bacteria elongate by inserting new cell wall material into the inner surface of the cell sidewall. This is performed by class A penicillin binding proteins (PBPs) and a highly conserved protein complex, the elongasome, which moves processively around the cell circumference and inserts long glycan strands that act as barrel-hoop-like reinforcing structures, thereby giving rise to a rod-shaped cell. However, it remains unclear how elongasome synthesis dynamics and termination events are regulated to determine the length of these critical cell-reinforcing structures. To address this, we developed a method to track individual elongasome complexes around the entire circumference of Bacillus subtilis cells for minutes-long periods using single-molecule fluorescence microscopy. We found that the B. subtilis elongasome is highly processive and that processive synthesis events are frequently terminated by rapid reversal or extended pauses. We found that cellular levels of RodA regulate elongasome processivity, reversal and pausing. Our single-molecule data, together with stochastic simulations, show that elongasome dynamics and processivity are regulated by molecular motor tug-of-war competition between several, likely two, oppositely oriented peptidoglycan synthesis complexes associated with the MreB filament. Altogether these results demonstrate that molecular motor tug-of-war is a key regulator of elongasome dynamics in B. subtilis, which likely also regulates the cell shape via modulation of elongasome processivity.

PBP-A, a cyanobacterial dd-peptidase with high specificity for amidated muropeptides, exhibits pH-dependent promiscuous activity harmful to Escherichia coli

Penicillin binding proteins (PBPs) are involved in biosynthesis, remodeling and recycling of peptidoglycan (PG) in bacteria. PBP-A from Thermosynechococcus elongatus belongs to a cyanobacterial family of enzymes sharing close structural and phylogenetic proximity to class A β-lactamases. With the long-term aim of converting PBP-A into a β-lactamase by directed evolution, we simulated what may happen when an organism like Escherichia coli acquires such a new PBP and observed growth defect associated with the enzyme activity. To further explore the molecular origins of this harmful effect, we decided to characterize deeper the activity of PBP-A both in vitro and in vivo. We found that PBP-A is an enzyme endowed with dd-carboxypeptidase and dd-endopeptidase activities, featuring high specificity towards muropeptides amidated on the d-iso-glutamyl residue. We also show that a low promiscuous activity on non-amidated peptidoglycan deteriorates E. coli’s envelope, which is much higher under acidic conditions where substrate discrimination is mitigated. Besides expanding our knowledge of the biochemical activity of PBP-A, this work also highlights that promiscuity may depend on environmental conditions and how it may hinder rather than promote enzyme evolution in nature or in the laboratory.

Evolution of mutations in the ftsI gene leading to amino acid substitutions in PBP3 in Haemophilus influenzae strains under the selective pressure of ampicillin and cefuroxime

BackgroundAminopenicillins are recommended agents for non-invasive Haemophilus influenzae infections. One of the mechanisms of resistance to β-lactams is the alteration of the transpeptidase region of penicillin binding protein 3 (PBP3) which is caused by mutations in the ftsI gene. It was shown that exposure to beta-lactams has a stimulating effect on increase of prevalence of H. influenzae strains with the non-enzymatic mechanism of resistance. ObjectivesThe aim of our study was to compare the mutational potential of ampicillin and cefuroxime in H. influenzae strains, determination of minimum inhibitory concentration and the evolution of mutations over time, focusing on amino acid substitutions in PBP3. Methods30 days of serial passaging of strains in liquid broth containing increasing concentrations of ampicillin or cefuroxime was followed by whole-genome sequencing. ResultsOn average, cefuroxime increased the minimum inhibitory concentration more than ampicillin. The minimum inhibitory concentration was increased by a maximum of 32 fold. Substitutions in the PBP3 started to appear after 15 days of passaging. In PBP3, cefuroxime caused different substitutions than ampicillin. ConclusionsOur experiment observed differences in mutation selection by ampicillin and cefuroxime. Selection pressure of antibiotics in vitro generated substitutions that do not occur in clinical strains in the Czech Republic.

Investigation of SCCmec types using the real time PCR method in cefoxitin-resistant Staphylococcus aureus isolates

BackgroundMethicillin-resistant Staphylococcus aureus (MRSA) is an important pathogen that can cause many community and hospital-acquired infections. This study was conducted to investigate the SCCmec gene types responsible for methicillin resistance in MRSA isolates isolated from hospitalised patients. Material and methodsMRSA isolates isolated from samples sent from various clinics to Gaziantep University Hospital Microbiology Laboratory between March 2021–January 2022 were included in the study. Bacteria were identified using by VITEK 2 automated system. Cefoxitin (FOX) resistance was determined by the disc diffusion method according to EUCAST standards. Cefoxitin resistance was confirmed by the Penicillin Binding Protein 2′ latex agglutination test. Types of mecA, mecC, coa, nuc, Panton Valentin Leukocidin (PVL), ccrC2, class A mec, SCCmec types in isolates detected as MRSA were investigated by real-time PCR. ResultsIn this study, 116 isolates meeting the study criteria were examined. By detecting the nuc and coa genes in all isolates by PCR, the phenotypic identification of S.aureus was confirmed. While the mecA gene was detected in all MRSA isolates, no mecC gene was detected in any isolates. Detected SCCmec types were as follows; SCCmec Type 1 (2.6%), Type II (28.4%), Type III (12.9%), Type IVa (11.2%), Type IVb (3.4%), Type IVc (3.4%), Type IVg (12.1%), Type V (0.9%), Type VII (4.3%), Type VIII (18.1%), Type IX (0.9%), Type XII (1.7%). On the other hand, SCCmec Type VI, X, XI and XIII were not found in any isolate. It was determined that four of the MRSA isolates (3.4%) carried the PVL gene that two (50%) of these were found in SCCmec Type VIII. ConclusionMonitoring of FOX resistance is an effective and safe method for determination of MRSA isolates. The change in the mec gene causes resistance, which should be monitored regularly with molecular methods. Our study is the first study in Turkey.

Exploration of the role of the penicillin binding protein 2c (Pbp2c) in inducible β-lactam resistance in Corynebacteriaceae.

Six genes encoding putative high molecular weight penicillin-binding proteins (Pbp) are present in the genome of the β-lactam-resistant strain Corynebacterium jeikeium K411. In this study, we show that pbp2c, one of these six genes, is present in resistant strains of Corynebacteriaceae but absent from sensitive strains. The molecular study of the pbp2c locus from C. jeikeium and its heterologous expression in Corynebacterium glutamicum allowed us to show that Pbp2c confers high levels of β-lactam resistance to the host and is under the control of a β-lactam-induced regulatory system encoded by two adjacent genes, jk0410 and jk0411. The detection of this inducible resistance may require up to 48 h of incubation, particularly in Corynebacterium amycolatum. Finally, the Pbp2c-expressing strains studied were resistant to all the β-lactam antibiotics tested, including carbapenems, ceftaroline, and ceftobiprole.

In vitro antibacterial activity of antibiotics and plant essential oils against Escherichia coli MTCC443 supported through the molecular docking and pharmacokinetics study.

Most of the Escherichia coli turned into serious pathogens or developed antibiotic resistance, mainly due to their ability to show different phenotypic traits. In order to overcome the resistance to these antibiotics, the use of essential oils (EOs) is of great significance against highly pathogenic microorganisms. This study has been made to compare the in vitro antibacterial activity and further validated the same through the molecular docking study of 13 antibiotics such as ciprofloxacin, chloramphenicol, erythromycin, ampicillin, cefotaxime, rifampicin, kanamycin, vancomycin, streptomycin, penicillin, nalidixic acid, trimethoprim, and polymyxin, and 10 EOs such as garlic, tulsi, neem, clove, thyme, peppermint, coriander, tea, lavender, and eucalyptus against the target protein (DNA gyrase) of E. coli MTCC443. E. coli Microbial Type Culture Collection 443 was found to be highly sensitive to ciprofloxacin (zone of inhibition [ZOI], 2.5cm ±0.1) and chloramphenicol (ZOI, 1.8cm ±0.1), whereas garlic oil (ZOI, 5.5cm ±0.1) and coriander oil (ZOI, 4.4cm ±0.1) were found comparatively most effective. Further, the in silico investigation observed the same; ciprofloxacin (binding affinity: -7.2kcal/mol) and chloramphenicol (binding affinity: -6.6kcal/mol). Penicillin (binding affinity: -4.2kcal/mol) and polymyxin (binding affinity: -0.3kcal/mol) were found to be least effective against the tested microbe, whereas vancomycin (binding affinity: +0.8kcal/mol) had no effect on it. Garlic (binding affinity: -7.8kcal/mol), coriander (binding affinity: -6.8kcal/mol), peppermint (binding affinity: -6.2kcal/mol), and neem (binding affinity: -6.2kcal/mol) oil exhibited the potent antibacterial activity against E. coli MTCC443, whereas thyme (binding affinity: -6.1kcal/mol), tea tree (binding affinity: -4.9kcal/mol), and tulsi (binding affinity: -3.8kcal/mol) oil were observed moderately effective. Eucalyptus (binding affinity: -2.9kcal/mol) and lavender (binding affinity: -2.8kcal/mol) oil were found to be the least effective among all the oils tested. The pharmacokinetics and networking were performed to the pharmacology of the potential compounds.

In silico exploration of phenolics as modulators of penicillin binding protein (PBP) 2× of Streptococcus pneumoniae

Infections caused by multidrug-resistant Streptococcus pneumoniae remain the leading cause of pneumonia-related deaths in children < 5 years globally, and mutations in penicillin-binding protein (PBP) 2 × have been identified as the major cause of resistance in the organism to beta-lactams. Thus, the development of new modulators with enhanced binding of PBP2x is highly encouraged. In this study, phenolics, due to their reported antibacterial activities, were screened against the active site of PBP2x using structure-based pharmacophore and molecular docking techniques, and the ability of the top-hit phenolics to inhibit the active and allosteric sites of PBP2x was refined through 120 ns molecular dynamic simulation. Except for gallocatechin gallate and lysidicichin, respectively, at the active and allosteric sites of PBP2x, the top-hit phenolics had higher negative binding free energy (ΔGbind) than amoxicillin [active site (− 19.23 kcal/mol), allosteric site (− 33.75 kcal/mol)]. Although silicristin had the best broad-spectrum effects at the active (− 38.41 kcal/mol) and allosteric (− 50.54 kcal/mol) sites of PBP2x, the high thermodynamic entropy (4.90 Å) of the resulting complex might suggest the need for its possible structural refinement for enhanced potency. Interestingly, silicristin had a predicted synthetic feasibility score of < 5 and quantum calculations using the DFT B3LYP/6-31G+ (dp) revealed that silicristin is less stable and more reactive than amoxicillin. These findings point to the possible benefits of the top-hit phenolics, and most especially silicristin, in the direct and synergistic treatment of infections caused by S. pneumoniae. Accordingly, silicristin is currently the subject of further confirmatory in vitro research.

Identification of small molecule inhibitors of penicillin-binding protein 2a of methicillin-resistant Staphylococcus aureus for the therapeutics of bacterial infection.

The penicillin binding protein 2a (PBP2a) is a key enzyme associated with bacterial cell wall synthesis and bacterial infection. Therefore, targeting PBPa2 offers a promising approach for the therapeutics of bacterial resistance and infection. This study presents a comprehensive analysis of alpha-mangostin as a potential inhibitor of PBPa2. Molecular docking simulations revealed a strong binding affinity between alpha-mangostin and PBP2a, with an affinity score of -6.01 kcal/mol. Notably, alpha-mangostin formed a preferential hydrogen bond with THR216 of PBP2a, alongside several other polar and hydrophobic interactions. ADME and Toxicity predictions indicated that alpha-mangostin possesses favourable pharmacokinetic properties, suggesting its potential as a therapeutic agent. PASS analysis further highlighted its broad range of favourable biological properties. SwissTargetPrediction analysis reinforced these findings, indicating alpha-mangostin's association with various biological processes. Cell toxicity assays demonstrated that alpha-mangostin had no significant impact on the viability of HEK-293 cells, suggesting its potential safety for further development. The IC50 value for alpha-mangostin was found to be 33.43µM. Fluorescence-based binding assays showed that alpha-mangostin effectively inhibited PBP2a activity in a concentration-dependent manner, supporting its role as an inhibitor. In conclusion, the results suggest alpha-mangostin as a promising candidate for inhibiting PBP2a. Further, extensive studies are warranted to explore its clinical applications.

Next generation antibiotic combinations to combat pan-drug resistant Klebsiella pneumoniae

Antimicrobial resistance has emerged as one of the leading public health threats of the twenty-first century. Gram-negative pathogens have been a major contributor to the declining efficacy of antibiotics through both acquired resistance and tolerance. In this study, a pan-drug resistant (PDR), NDM-1 and CTX-M-15 co-producing isolate of K. pneumoniae, CDC Nevada, (Kp Nevada) was exposed to the clinical combination of aztreonam + ceftazidime/avibactam (ATM/CAZ/AVI) to overcome metallo-β-lactamases. Unexpectedly, the β-lactam combination resulted in long filamentous cell formation induced by PBP3 inhibition over 168 h in the hollow fiber infection model experiments with eventual reversion of the total population upon drug removal. However, the addition of imipenem to the two drug β-lactam combination was highly synergistic with suppression of all drug resistant subpopulations over 5 days. Scanning electron microscopy and fluorescence microscopy for all imipenem combinations in time kill studies suggested a role for imipenem in suppression of long filamentous persisters, via the formation of metabolically active spheroplasts. To complement the imaging studies, salient transcriptomic changes were quantified using RT-PCR and novel cassette assay evaluated β-lactam permeability. This showed significant upregulation of both spheroplast protein Y (SPY), a periplasmic chaperone protein that has been shown to be related to spheroplast formation, and penicillin binding proteins (PBP1, PBP2, PBP3) for all combinations involving imipenem. However, with aztreonam alone, pbp1, pbp3 and spy remained unchanged while pbp2 levels were downregulated by > 25%. Imipenem displayed 207-fold higher permeability as compared with aztreonam (mean permeability coefficient of 17,200 nm/s). Although the clinical combination of aztreonam/avibactam and ceftazidime has been proposed as an important treatment of MBL Gram-negatives, we report the first occurrence of long filamentous persister formation. To our knowledge, this is the first study that defines novel β-lactam combinations involving imipenem via maximal suppression of filamentous persisters to combat PDR CDC Nevada K. pneumoniae.

Computational Study of Antimicrobial Peptides for Promising Therapeutic Applications Against Methicillin-resistant Staphylococcus Aureus.

Methicillin-resistant Staphylococcus aureus (MRSA) is a causative agent for multiple drug-resistant diseases and is a prime health concern. Currently, antibiotics like vancomycin, daptomycin, fluoroquinolones, linezolid, fifth-generation cephalosporin and others are available in the market for the treatment of MRSA infection. With the increasing prevalence of drug-resistant cases, researchers are actively investigating alternative strategies to combat MRSA, including the exploration of peptide therapeutics. This study employed computational methods to prospect for potential Antimicrobial Peptides (AMPs). A total of One hundred and fifty antimicrobial peptides were explored based on physicochemical properties. The results showed that Clavanin B was the most appropriate candidate. Molecular Docking and Molecular Dynamics Simulation results showed the protein-peptide interaction of the MRSA target proteins, Penicillin Binding Protein 2a and Panton-Valentine Leukocidin Toxin, with the Antimicrobial Peptide Clavanin B. Currently, the antimicrobial peptide database highlights Clavanin B's role as an anti-HIV peptide. Moreover, this investigation proposes Clavanin B as a viable repurposed drug for treating MRSA, underscoring its potential deployment in the management of MRSA infections.

IN SILICO SCREENING OF PHYTOCONSTITUENTS OF CISSUS QUADRANGULARIS AND CHROMOLAENA ODORATA AGAINST PROTEINS OF ANTIMICROBIAL RESISTANCE AND WOUND HEALING

In silico screening is a methodological approach, which is invaluable for rational drug design and the identification of potential therapeutic agents. In the context of antibiotic-resistant infectious wounds, molecular docking can provide a deeper understanding of how phytocompounds might interfere with bacterial virulence and antibiotic resistance. In this study, proteins involved in antimicrobial resistance and wound healing were docked against major phytoconstituents of ethyl acetate extract of Cissus quadrangularis (EACQ) and ethanol extract of Chromolaena odorata (EECO), two medicinal plants that have been traditionally used. Receptor structures for interleukin 6 (PDB id: 1n26) of human and mice, IL6 (Uniprot id p 20607) of rat, vascular endothelial growth factor (VEGFR, PDB id: 2ctw) for human, mice, rat and penicillin binding protein 2a (PBP2a, PDB id: 1vqq) of S. aureus were downloaded from the database of the RCSB protein data bank. The ligand structures were downloaded from PubChem compound database in structure data file (.SDF) format. The docking studies were conducted using Autodock4. and the results of the docking analysis were visualised using Discovery Studio Visualizer. The docking log (dlg) file, featuring an RMSD table, provides binding energy values in Kcal/mol for each molecule at its optimal docked postures, offering insights into structural accuracy and ligand-receptor interaction strength in molecular docking simulations. In silico analysis of ligands showed that squalene of EACQ and epilupeol of EECO had the least binding energy towards proteins of antimicrobial resistance and wound healing. Thus, these compounds could emerge as promising lead molecules against infectious wounds.

Design, synthesis, characterization, antimicrobial activity, cytotoxicity, molecular docking, and in-silico ADMET analysis of the novel cefuroxime derivatives

This research aims to design and synthesize novel derivatives of Cefuroxime to evaluate their antibacterial effectiveness in comparison to Cefuroxime and to decrease resistance.Schotten Baumann's reaction synthesizes anhydride from acyl chlorides and carboxylate anion. Cefuroxime sodium was reacted with benzoyl chloride, 4-bromobenzoyl chloride, and 4-nitrobenzoyl chloride to make benzoyl derivatives. The derivatives were characterized using spectral analysis. Antimicrobial activity, cytotoxicity, in-silico molecular docking with nine different class of (Penicillin Binding Proteins) PBPs, and ADMET analysis were assessed for the analogs.Three molecules, Cef-1, Cef-2, and Cef-3, are synthesized from benzoyl derivatives. In various organisms, the derivatives outperformed Cefuroxime in antimicrobial activity. In many organisms, Cef-1 has the highest zone of inhibition. Cef-1 and Cef-3 inhibit Klebsiella pneumoniae better than Cef-2 and Cefuroxime. The greatest Cef-2-induced inhibition zone in Salmonella Typhimurium was 29.33 ± 0.47 mm. Significant antimicrobial susceptibility test activity was observed with lower inhibitory concentration (12.5 μg/ml) of derivatives compared to Cefuroxime across many species. Compound cytotoxicity is low, according to research. The consensus docking scores show that all synthesized derivatives bind better than cefuroxime. According to the results of the study, Cef-3 has the strongest correlation with PBP1a, PBP2a, PBP3, PBP4, and PBP6, whereas Cef-2 has a stronger association with PBP1b, PBP2b, PBP2x, and PBP5. Like Cef-2, Cef-1 has a greater affinity for PBP2x. Docking research indicated that all drugs bound better than Cefuroxime, indicating superior antibacterial efficacy. The ADMET studies showed oral bioavailability increased by increasing lipophilicity score 0.17 and cefuroxime 0.11.

Platanosides from Platanus × acerifolia: New molecules, SAR, and target validation of a strong lead for drug-resistant bacterial infections and the associated sepsis

Three undescribed (1–3) and nine known (4–12) platanosides were isolated and characterized from a bioactive extract of the May leaves of Platanus × acerifolia that initially showed inhibition against Staphylococcus aureus. Targeted compound mining was guided by an LC-MS/MS-based molecular ion networking (MoIN) strategy combined with conventional isolation procedures from a unique geographic location. The novel structures were mainly determined by 2D NMR and computational (NMR/ECD calculations) methods. Compound 1 is a rare acylated kaempferol rhamnoside possessing a truxinate unit. 6 (Z,E-platanoside) and 7 (E,E-platanoside) were confirmed to have remarkable inhibitory effects against both methicillin-resistant S. aureus (MIC: ≤ 16 μg/mL) and glycopeptide-resistant Enterococcus faecium (MIC: ≤ 1 μg/mL). These platanosides were subjected to docking analyses against FabI (enoyl-ACP reductase) and PBP1/2 (penicillin binding protein), both of which are pivotal enzymes governing bacterial growth but not found in the human host. The results showed that 6 and 7 displayed superior binding affinities towards FabI and PBP2. Moreover, surface plasmon resonance studies on the interaction of 1/7 and FabI revealed that 7 has a higher affinity (KD = 1.72 μM), which further supports the above in vitro data and is thus expected to be a novel anti-antibacterial drug lead.