Structural, molecular motions, and free-energy landscape of Leishmania sterol-14α-demethylase wild type and drug resistant mutant: a comparative molecular dynamics study

Evaluation of the effects of amitraz on the enzyme activity and stability of lysozyme: Spectroscopic and MD simulation approach

The binding interaction of food preservatives and pesticides has emerged as a matter of paramount importance as it not only presents potential health hazards but also carries substantial consequences for food processing and preservation. Herein, the mechanism of interaction between lysozyme and Amitraz was explored through spectroscopic and computational techniques. Spectral investigations indicated the spontaneous nature and stability of the lysozyme-Amitraz complex. The corresponding CD and FT-IR studies proved the structural changes of lysozyme. The presence of amitraz led to a notable decrease in both the enzymatic activity and thermal stability of lysozyme. Molecular docking demonstrated the preferred mode of interaction, and molecular dynamics simulations confirmed the stability of the resultant complex. In conclusion, the alarming findings of the lysozyme-Amitraz interaction underscore its detrimental impact on food safety and human health. Accordingly, urgent measures are imperative to address and mitigate the potential hazards posed by such interactions in food production.

Computational insight into crucial interaction between Pcf11 and Ydh1 for pre-mRNA 3'-end processing

Pre-mRNA processing in eukaryotes involves capping, splicing, cleavage, and polyadenylation. Various proteins regulating this key transcriptional event in humans share considerable homology with Saccharomyces cerevisiae proteins. Among these proteins, Pcf11 is a crucial component of the yeast CF IA sub-unit, and Ydh1 is part of the CPF sub-unit. Both these proteins have a significant role during the pre-mRNA processing of the nascent transcription. Our in silico analysis highlights probable interaction between residues of Pcf11-Ydh1 and their role in mRNA processing events. These outcomes provide evidence for direct interaction between the domain from residues 116 to 204 of Pcf11 (Pcf11116-204) with the N-terminal region of Ydh1 (residues 1-246; Ydh11-246). Molecular docking and MD simulations shed light on the structure and dynamics of the protein-protein complex that includes binding affinity and binding interface of Pcf11 and Ydh1 interaction. These outcomes would pave the way to further design in vitro and in vivo studies to determine the function of the Pcf11116-204 domain, which has not been previously analyzed; this would also facilitate deciphering the crucial role of Ydh1 and Pcf11 in assembling the cleavage and polyadenylation complex for executing co-transcriptional processing to generate mature mRNA.

In vitro and in silico evaluation of the anti-leishmania activity of synthetic chalcones

Leishmaniasis is a group of neglected, vector-borne infectious diseases that affect millions of people around the world. The medications available for its treatment, especially in cases of visceral leishmaniasis, are old, outdated and have serious side effects. In this work, 10 chalcones were synthesised and evaluated in vitro against promastigotes and axenic amastigotes of Leishmania infantum. Compounds CP04 and CP06 were the most promising, respectively presenting IC50 values = 13.64 ± 0.25 and 11.19 ± 0.22 µM against promastigotes, and IC50 = 18.92 ± 0.05 and 22.42 ± 0.05 µM against axenic amastigotes. Only compound CP04 did not show cytotoxicity against peripheral blood mononuclear cells (PBMCs). Molecular docking studies conducted with sterol 14-alpha demethylase (CYP-51) (PDB: 3L4D) and trypanothione reductase (PDB: 5EBK) enzymes from L. infantum evidenced the great affinity of compound CP04 for these targets, presenting Moldock score values of -94.0758 and -50.5692 KJ/mol-1.

Probing the toxic effect of chlorpyrifos as an environmental pollutant on the structure and biological activity of lysozyme under physiological conditions

The pervasive use of pesticides like chlorpyrifos (CPY) has been associated with deleterious effects on biomolecules, posing significant risks to environmental integrity, public health, and overall ecosystem equilibrium. Accordingly, in this study, we investigated the potential binding interaction between the well-conserved enzyme, lysozyme (LSZ), and CPY through various spectroscopic techniques and molecular modeling. The UV-vis absorption and fluorescence experiments confirmed the complex formation and static quenching of the intrinsic fluorescence intensity. LSZ revealed a singular binding site for CPY, with binding constants around 105 M-1 across different temperature ranges. Analysis of thermodynamic parameters showed the spontaneous nature of the complexation process, while also revealing the pivotal role of hydrophobic interactions in stabilizing the LSZ-CPY system. According to circular dichroism and Fourier transform infrared studies, CPY binding changed the secondary structure of LSZ by boosting α-helix presence and reducing the levels of β-sheet and β-turn content. Further, CPY decreased the stability and activity of LSZ. Computational docking delineated the specific and highly preferred binding site of CPY within the structure of LSZ. Molecular dynamic simulation indicated the enduring stability of the LSZ/CPY complex and revealed structural modifications in the LSZ after binding with CPY. This research provides a detailed understanding of the intermolecular dynamics between CPY and LSZ, concurrently elucidating the molecular-level implications for the potential hazards of pesticides in the natural environment.

The Application of MD Simulation to Lead Identification, Vaccine Design, and Structural Studies in Combat against Leishmaniasis - A Review

Drug discovery, vaccine design, and protein interaction studies are rapidly moving toward the routine use of molecular dynamics simulations (MDS) and related methods. As a result of MDS, it is possible to gain insights into the dynamics and function of identified drug targets, antibody-antigen interactions, potential vaccine candidates, intrinsically disordered proteins, and essential proteins. The MDS appears to be used in all possible ways in combating diseases such as cancer, however, it has not been well documented as to how effectively it is applied to infectious diseases such as Leishmaniasis. As a result, this review aims to survey the application of MDS in combating leishmaniasis. We have systematically collected articles that illustrate the implementation of MDS in drug discovery, vaccine development, and structural studies related to Leishmaniasis. Of all the articles reviewed, we identified that only a limited number of studies focused on the development of vaccines against Leishmaniasis through MDS. Also, the PCA and FEL studies were not carried out in most of the studies. These two were globally accepted utilities to understand the conformational changes and hence it is recommended that this analysis should be taken up in similar approaches in the future.

Free energy landscape and thermodynamics properties of novel mutations in PncA of pyrazinamide resistance isolates of Mycobacterium tuberculosis

Pyrazinamide (PZA) is one of the first-line antituberculosis therapy, active against non-replicating Mycobacterium tuberculosis (Mtb). The conversion of PZA into pyrazinoic acid (POA), the active form, required the activity of pncA gene product pyrazinamidase (PZase) activity. Mutations occurred in pncA are the primary cause behind the PZA resistance. However, the resistance mechanism is important to explore using high throughput computational approaches. Here we aimed to explore the mechanism of PZA resistance behind novel P62T, L120R, and V130M mutations in PZase using 200 ns molecular dynamics (MD) simulations. MD simulations were performed to observe the structural changes for these three mutants (MTs) compared to the wild types (WT). Root means square fluctuation, the radius of gyration, free energy landscape, root means square deviation, dynamic cross-correlation motion, and pocket volume were found in variation between WT and MTs, revealing the effects of P62T, L120R, and V130M. The free energy conformational landscape of MTs differs significantly from the WT system, lowering the binding of PZA. The geometric shape complementarity of the drug (PZA) and target protein (PZase) further confirmed that P62T, L120R, and V130M affect the protein structure. These effects on PZase may cause vulnerability to convert PZA into POA.Communicated by Ramaswamy H. Sarma.

Complexes of fluconazole with alanine, lysine and threonine: mass spectrometry and theoretical modeling

Investigation of the triazole-derived drugs action mechanisms and understanding of their affinity and specificity molecular basis may contribute to the new drugs development. The study was aimed to investigate the triazoles class representative (fluconazole) complexes with amino acids using mass spectrometry, molecular dynamics and ab initio quantum chemistry calculations. During the experimental study, the fluconazole, alanine, lysine and threonine solutions were analyzed by electrospray ionization mass spectrometry and tandem mass spectrometry. The molecular dynamics modeling of the fluconazole–amino acid complexes was performed using the CHARMM force field. The quantum chemistry calculations of the complexes structure and energy parameters were carried out using the density-functional theory by B3LYP calculations (3-21G and 6-311++G** basis sets). Mass spectra indicated that fluconazole formed stable complexes with amino acids in the 1 : 1 stoichiometric ratio. In accordance with the tandem mass spectrometry with varying fluconazole–amino acid associates ion fragmentation energy, the following sequence was obtained: [Fluc + Ala + H]+ < [Fluc + Lys + H]+ < [Fluc + Thr + H]+. The fluconazole–amino acid interaction energy values resulting from the quantum chemistry calculations formed the sequence similar to that obtained by experiment. Thus, as seen in the case of fluconazole–amino acid complexes, it is possible to combine the experimental mass spectrometry studies with quantum chemical modeling for the complexes properties assessment.

In vitro and in silico analysis of L. donovani enoyl acyl carrier protein reductase - A possible drug target

The emergence of increased resistance to the available drugs has created a situation that demands to find out more specific molecular drug targets for Leishmaniasis. The enoyl acyl carrier protein reductase (ENR), a regulatory enzyme in type II fatty acid synthesis, was confirmed as a novel drug target and triclosan as its specific inhibitor in many microorganisms. In this study, the triclosan was tested for the leishmanicidal property against Leishmania donovani (L. donovani) and the results of in vitro and ex vivo drug assays on promastigotes and amastigotes showed that triclosan possessed antileishmanial activity with a half minimal inhibitory concentration (IC₅₀) of 30 µM. Consequently, adopting in silico approach, we have tested the triclosan's ability to bind with the L. donovani enoyl acyl carrier protein reductase (LdENR). The 3D structure of LdENR was modelled, triclosan and cofactors were docked in LdENR model and molecular dynamic simulations were performed to observe the protein-ligands interactions, stability, compactness and binding energy calculation of the ligands-LdENR complexes. The observation showed that triclosan stably interacted with LdENR in presence of both the cofactors (NADPH and NADH), however, simulation results favor NADH as a preferred co-factor for LdENR. These results support that the reduction of L. donovani growth in the in vitro and ex vivo drug assays may be due to the interaction of triclosan with LdENR, which should be confirmed through enzymatic assays. The results of this study suggest that LdENR could be a potential drug target and triclosan as a lead for Leishmaniasis.Communicated by Ramaswamy H. Sarma.

LeishInDB: A web-accessible resource for small molecule inhibitors against Leishmania sp

Despite the availability of drugs to treat Leishmaniasis, various other factors including drug resistance and adverse side effects encourage the researchers to search for new strategies and alternatives for treating Leishmaniasis. Repurposing and devising combination therapy with the existing small molecules would serve as an alternative strategy to address the issue, especially the drug resistance. Hence, here we report LeishInDB, a web-accessible resource of small molecule inhibitors having a varying degree of activity towards Leishmania sp. The database includes searchable information of >7000 small molecules collected from >600 literature. The comprehensive information of inhibitors mainly include the activity details (IC50, EC50, Ki, binding energy etc., if any); information on species and form of Leishmania the inhibitor is active against; and the details about their protein target (actively linked to TriTrypDB). In addition, chemical properties including the log P-value, number of rotatable bonds, number of hydrogen bond donors and acceptors, molecular weight, 2D/3D structural information etc., were also included. Toxicity prediction for each molecule was performed using admetSAR and their corresponding results were available to perform the filtered search. In addition, facility to perform sub-structure search, facility to perform the dynamic search on various fields, and facility to download all the structure of molecules that match the search criteria were also included. We believe that the scope of LeishInDB allows the researchers to utilize the available information for repurposing the inhibitors as well as for the investigation of new therapeutics. Database URL:http://leishindb.biomedinformri.com/.

Identification of protegrin-1 as a stable and nontoxic scaffold among protegrin family - a computational approach

Achieving both, nontoxicity and stability in antimicrobial peptides (AMP) is a challenge. This study predicts a structurally stable, nontoxic scaffold among the protegrin family, for future therapeutic peptide analogs. Protegrins (PG) are a class of pharmaceutically approved, in demand AMPs, which require further improvement in terms of nontoxicity and stability. Out of five protegrins viz., PG1, PG2, PG3, PG4 and PG5, PG1 has been predicted as best scaffold. Prediction was based upon sequential elimination of other protegrins, using computational methods to assess the extracellular bacterial membrane penetrability, nontoxicity and structural stability by geometric observables. Initially, PG2 and PG4 showing the lowest membrane penetrability and highest toxicity respectively, were screened out. Among the remaining three protegrins, PG1 displayed both lowest root mean square deviation and radius of gyration, with a considerable occupancy of seven H-bonds and established uniform secondary structure profile throughout its ensembles. Therefore, the authors claim the superiority of PG1 as a nontoxic stable scaffold among its family. Communicated by Ramaswamy H. Sarma.