Search

GenoVault is a cloud-based repository for handling Next Generation Sequencing (NGS) data. It is developed using OpenStack based private cloud with various services like keystone for authentication, cinder for block storage, neutron for networking and nova for managing compute instances for the Cloud. GenoVault uses object-based storage, which enables data to be stored as objects instead of files or blocks for faster retrieval from different distributed object nodes. Along with a web-based interface JavaFX-based desktop client has also been developed to meet the requirements of large file uploads ( > 5 GB) that is usually seen in NGS datasets. Users can store as many as one million files in their respective object based storage areas and the metadata provided by the user during file uploads is used for querying the database. GenoVault repository is designed taking into account future needs and hence can scale both vertically and horizontally without any need for modification in the design. Users have an option to make the data shareable to the public or restrict the access as private. Data security is ensured as every container is a separate entity in object-based storage architecture also supported by secured file transfer protocol during data upload and download. The data is uploaded by the user in their individual containers that include raw read files (fastq), processed alignment files (bam, sam, bed) and output of variation detection (vcf). GenoVault architecture allows verification of the data in terms of integrity and authentication before making it available to collaborators as per user permissions. GenoVault is useful for maintaining the organization wide NGS data generated by experiments in various labs which is not yet published and submitted to public repositories like NCBI. GenoVault also provides support to share NGS data among the collaborating institutions. GenoVault can thus manage vast volumes of NGS data on any OpenStack-based private cloud.

The transcription factor p53 is one of the most widely studied cancer proteins. Its temperature-sensitive nature suggests reduction in functionality at physiological temperatures. Temperature-induced conformational variations and their impact on its functional ability still remain unexplored. A total of 20.8 μs molecular dynamics simulations of wildtype p53 in the apo and the DNA-bound states have been performed at 300 K and 310 K. Further, Markov State Modeling (MSM) analyses were performed, considering C

cWnt-signalling plays a crucial role in stem cell maintenance and tissue homeostasis. Secreted frizzled-related proteins(SFRP), Wnt inhibitors consist of the N-terminal cysteine rich domain(CRD) and the C-terminal netrin(NTR) domain. SFRP1 binds to the Wnt ligands and frizzled receptors(FZ) either through its SFRP1CRD or through its SFRP1Netrin domains; however, very little is known on these binding affinities. Here, we attempted to understand the interactions and binding affinities of SFRP1-Wnt5B, SFRP1-FZ(2, 3 & 7) and Wnt5B-FZ(2, 3 & 7) that are mainly expressed in murine hair follicle stem cells. SFRP1CRD, SFRP1Netrin, Wnt5B and FZ(2, 3 & 7) structures were built using homology modelling, followed by their molecular dynamics simulations. SFRP1CRD showed lower fluctuation when in complex with FZ2, FZ3 and FZ7 and Wnt5B as compared to SFRP1Netrin using RMSF and RMSD. However, free energy showed SFRP1Netrin was energetically more stable than SFRP1CRD. SFRP1Netrin formed more number of interactions with FZ as compared to SFRP1CRD. Importantly, SFRP1Netrin favoured binding to the FZ receptors(FZ3 > FZ7 > FZ2) as compared to Wnt5B ligand. Conversely, the SFRP1CRD showed more affinity towards the Wnt5B ligand as compared to FZ receptors. Wnt5B showed the best binding affinity with FZ3 followed by SFRP1CRD and SFRP1Netrin. Therefore, SFRP1Netrin can bind to the FZ3 with higher binding affinity and may inhibit non-canonical Wnt-signalling pathway. Our study provides the comprehensive information on the binding affinities among the Wnt5B, SFRP1CRD/Netrin and FZ(2, 3 & 7). Thus, this information might also help in designing novel strategies to inhibit aberrant Wnt-signalling. Communicated by Ramaswamy H. Sarma

Alzheimer's disease is characterized by amyloid-β aggregation. Currently, all the approved medications are to treat the symptoms but there is no clinically approved treatment for the cure or to prevent the progression of Alzheimer's disease (AD). Earlier reports suggest the use of small molecules and peptides to target and destabilize the amyloid fibril. The use of Beta Sheet Breaker (BSB) peptides seems to be a promising and attractive therapeutic approach as it can strongly bind and destabilize the preformed amyloid fibril. There are experimental studies describing the destabilization role of various BSB peptides, but the exact mechanism remains elusive. In the current work, an attempt is made to study the destabilization mechanism of different BSB peptides on preformed amyloid protofibril using molecular docking and simulations. Molecular docking of eight different BSB peptides of varying length (5-mer to 10-mer) on the Abeta protofibril was done. Docking was followed by multiple sets of molecular simulations for the Abeta protofibril-BSB peptide complex for each of the top ranked poses of the eight BSB peptides. As a control, multiple sets of simulations for the Abeta protofibril (APO) were also carried out. An increase in the RMSD, decrease in the number of interchain hydrogen bonds, destabilization of important salt bridge interactions (D23-K28), and destabilization of interchain hydrophobic interactions suggested the destabilization of Abeta protofibril by BSB peptides. The MM-GBSA free energy of binding for each of the BSB peptides was calculated to measure the binding affinity of BSB peptides to Abeta protofibril. Further residue wise contribution of free energy of binding was also calculated. The study showed that 7-mer peptides tend to bind strongly to Abeta protofibril as compared to other BSB peptides. The KKLVFFA peptide showed better destabilization potential as compared to the other BSB peptides. The details about the destabilization mechanism of BSB peptides will help in the design of other peptides for the therapeutic intervention for AD.

Background: Balchaturbharda Churna (BC), is four ingredients (Aconitum heterophyllum Wall. Ex Royle, Pistacia integerrima stew. Ex brandis, Piper Longum Linn. and Cyperus rotundus linn.) Ayurvedic powder dosage form, which is commonly prescribed for treating fever, cough, diarrhea in pediatric setting.Objective: This present study evaluates the possible effect of phytochemicals from the ingredients of BC on SARS-CoV-2 main protease (MPro), RNA dependent RNA polymerase (RdRP) and spike-ACE2 (SA) complex through in silico evaluation. Materials and methods: X-ray crystal structure of MPro and SA complex with PDB IDs 6LU7 and 6LZG and the SWISS model of RdRP were used as the drug targets. An enhanced docking methodology has been implemented to perform the molecular docking of these phytochemicals against the above-mentioned drug targets of SARS-CoV-2. DOCK 6 was used to perform docking of these phytochemicals. The ADMET and drug likeliness properties for these selected phytochemicals was performed using SWISS ADME. Results: The ensemble docking studies suggest that aconitine, lappaaconitine from Aconitum heterophyllum, 2’-hydroxyisorientin from Pistacia intergerrima and guineesine, pipercide and piperoic acid from Piper longum hold the potential to bind favorably with the SARS-CoV-2 drug targets. The drug likeliness and ADMET properties were calculated for these phytochemicals indicate that all the three phytochemicals from Piper longum were observed to have considerate drug-likeliness and ADMET properties. Aconitine has molecular weight slightly higher than 500 kDA and has more than 10 hydrogen bond acceptors. Conclusion: The in-silico study demonstrates that phytochmeicals from the ingredients BC viz., aconitine, lappaaconitine from Aconitum heterophyllum, 2’-hydroxyisorientin from Pistacia intergerrima and guineesine, pipercide and piperoic acid from Piper longum hold the potential to bind favourably with the SARS-CoV-2 drug targets. The study also provides evidence for drug likeliness and ADMET properties for these phytochemicals suggesting that BC can be further studied as potential drug of choice for treating SARS-CoV-2 infection in paediatric cases.

The COVID-19 pandemic has been responsible for several deaths worldwide. The causative agent behind this disease is the Severe Acute Respiratory Syndrome – novel Coronavirus 2 (SARS-nCoV2). SARS-nCoV2 belongs to the category of RNA viruses. The main protease, responsible for the cleavage of the viral polyprotein is considered as one of the hot targets for treating COVID-19. Earlier reports suggest the use of HIV anti-viral drugs for targeting the main protease of SARS-CoV, which caused SARS in the year 2002-03. Hence, drug repurposing approach may prove to be useful in targeting the main protease of SARS-nCoV2. The high-resolution crystal structure of 3CLpro (main protease) of SARS-nCoV2 (PDB ID: 6LU7) was used as the target. The Food and Drug Administration (FDA) approved and SWEETLEAD database of drug molecules were screened. The apo form of the main protease was simulated for a cumulative of 150 ns and 10 μs open source simulation data was used, to obtain conformations for ensemble docking. The representative structures for docking were selected using RMSD-based clustering and Markov State Modeling analysis. This ensemble docking approach for main protease helped in exploring the conformational variation in the drug binding site of the main protease leading to efficient binding of more relevant drug molecules. The drugs obtained as best hits from the ensemble docking possessed anti-bacterial and anti-viral properties. Small molecules with these properties may prove to be useful to treat symptoms exhibited in COVID-19. This in-silico ensemble docking approach would support identification of potential candidates for repurposing against COVID-19.

The efforts towards developing a potential drug against the current global pandemic, COVID-19, have increased in the past few months. Drug development strategies to target the RNA dependent RNA polymerase (RdRP) of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) are being tried worldwide. The gene encoding this protein, is known to be conserved amongst positive strand RNA viruses. This enables an avenue to repurpose the drugs designed against earlier reported inhibitors of RdRP. One such strong inhibitor is remdesivir which has been used against EBOLA infections. The binding of remdesivir to RdRP of SARS-CoV-2 has been studied using the classical molecular dynamics and ensemble docking approach. A comparative study of the simulations of RdRP in the apo and remdesivir-bound form revealed blocking of the template entry site in the presence of remdesivir. The conformation changes leading to this event were captured through principal component analysis. The conformational and thermodynamic parameters supported the experimental information available on the involvement of crucial arginine, serine and aspartate residues belonging to the conserved motifs in RdRP functioning. The catalytic site comprising of SER 759, ASP 760, and ASP 761 (SDD) was observed to form strong contacts with remdesivir. The significantly strong interactions of these residues with remdesivir may infer the latter's binding similar to the normal nucleotides thereby remaining unidentified by the exonuclease activity of RdRP. The ensemble docking of remdesivir too, comprehended the involvement of similar residues in interaction with the inhibitor. This information on crucial interactions between conserved residues of RdRP with remdesivir through in silico approaches may be useful in designing inhibitors.

The current wave of the COVID-19 pandemic is due to the B.1.1.529 variant of the SARS-CoV-2 designated as Omicron. AYUSH-64 a poly herbal drug developed by Central Council for Research in Ayurvedic Sciences (CCRAS) has been recommended by Ministry of AYUSH in asymptomatic, mild to moderate COVID-19 patients. One of the earlier in-silico studies had shown the binding of the constituents of AYUSH-64 to the SARS-CoV-2 drug targets. The current study proposes to understand their binding of the top four phytochemicals to the same drug targets of the Omicron variant with respect to crucial drug targets, main protease (Mpro) and receptor binding domain (RBD) of spike protein. An enhanced molecular docking methodology, namely, ensemble docking has been used in the particular study. Using MD simulations and clustering approach it was observed that the Mpro and RBD-spike of Omicron variant of SARS-CoV-2 tends to attain 4 and 8 conformational respectively. Docking these individual conformations with akummicine-N-oxide, akummiginone, echitamidine-n-oxide, and echitaminic acid revealed that the binding was better in case of the mutant as compared to the wild type. Hence, it can be inferred that, these phytochemicals from AYUSH-64 formulation may have the potential to act against the Omicron variant of SARS-CoV-2.

Molecular Dynamics simulation has been performed to study the effect of temperature on anti-cancer drug, carmustine, mediated by a graphene sheet. Root mean square deviation has been analysed at various temperatures, which is suggestive of the stability of the drug-graphene conjugate even at higher temperatures, although elevated diffusion of the drug at higher temperature has been observed as expected. Density functional theory is instrumental in determining the energetics of the drug action– from the generation of the active reacting species to the alkylation of DNA. By the energy profile, based on DFT, it is confirmed that it is the N7 site in guanine of the DNA major groove where the drug binds preferentially. The results provide a definitive insight into the release process as well as the effects of the chemotherapeutic carmustine drug and targets at generating a wholistic approach of drug-action.

The S-glycoprotein (Spike) of the SARS-CoV-2 forms a complex with the human transmembrane protein angiotensin-converting enzyme 2 (ACE2) during infection. It forms the first line of contact with the human cell. The FDA-approved drugs and phytochemicals from Indian medicinal plants were explored. Molecular docking and simulations of these molecules targeting the ACE2–Spike complex were performed. Rutin DAB10 and Swertiapuniside were obtained as the top-scored drugs as per the docking protocol. The MD simulations of ligand-free, Rutin DAB10-bound, and Swertiapuniside-bound ACE2–Spike complex revealed abrogation of the hydrogen bonding network between the two proteins. The principal component and dynamic cross-correlation analysis pointed out conformational changes in both the proteins unique to the ligand-bound systems. The interface residues, His34, and Lys353 from ACE2 and Arg403, and Tyr495 from the Spike protein formed significant strong interactions with the ligand molecules, inferring the inhibition of ACE2–Spike complex. Few novel interactions specific to Rutin-DAB10 and Swertiapuniside were also identified. The conformational flexibility of the drug-binding pocket was captured using the RMSD-based clustering of the ligand-free simulations. Ensemble docking was performed wherein the FDA-approved database and phytochemical dataset were docked on each of the cluster representatives of the ACE2–Spike. The phytochemicals identified belonged to Withania somnifera, Swertia chirayita, Tinospora cordifolia and Rutin DAB10, fulvestrant, elbasvir from FDA. Supplementary Information The online version contains supplementary material available at 10.1007/s11696-021-01680-1.

Amongst the scientific frameworks powered by the Monte Carlo (MC) toolkit Geant4 (Agostinelli et al., 2003), the TOPAS (Tool for Particle Simulation) (Perl et al., 2012) is one. TOPAS focuses on providing ease of use, and has significant implementation in the radiation oncology space at present. TOPAS functionality extends across the full capacity of Geant4, is freely available to non-profit users, and is being extended into radiobiology via TOPAS-nBIO (Ramos-Mendez et al., 2018). A current "grand problem" in cancer therapy is to convert the dose of treatment from physical dose to biological dose, optimized ultimately to the individual context of administration of treatment. Biology MC calculations are some of the most complex and require significant computational resources. In order to enhance TOPAS's ability to become a critical tool to explore the definition and application of biological dose in radiation therapy, we chose to explore the use of Field Programmable Gate Array (FPGA) chips to speedup the Geant4 calculations at the heart of TOPAS, because this approach called "Reconfigurable Computing" (RC), has proven able to produce significant (around 90x) (Sajish et al., 2012) speed increases in scientific computing. Here, we describe initial steps to port Geant4 and TOPAS to be used on FPGA. We provide performance analysis of the current TOPAS/Geant4 code from an RC implementation perspective. Baseline benchmarks are presented. Achievable performance figures of the subsections of the code on optimal hardware are presented; Aspects of practical implementation of "Monte Carlo on a chip" are also discussed.

There is an extensive research carrying out on antisense technology and the molecules entering into clinical trials are increasing rapidly. Phosphorothioate (PS) is a chemical modification in which nonbridged oxygen is replaced with a sulfur, consequently providing resistance against nuclease activity. The 2'-4' conformationally restricted nucleoside has the structural features of both 2'-O-methoxy ethyl RNA (MOE), which shows good toxicity profile, and locked nucleic acid (LNA), which shows good binding affinity towards the target RNA. These modifications have been studied and suggested that they can be a potential therapeutic agents in antisense therapy. Mipomersen (ISIS 301012), which contains the novel nucleoside modification has been used to target to apolipoprotein (Apo B), which reduces LDL cholesterol by 6-41%. In this study, classical molecular dynamics (MD) simulations were performed on six different antisense gapmer/target-RNA oligomer duplexes (LNA-PS-LNA/RNA, RcMOE-PS-RcMOE/RNA, ScMOE-PS-ScMOE/RNA, MOE-PS-MOE/RNA, PS-DNA/RNA and DNA/RNA) to investigate the structural dynamics, stability and solvation properties. The LNA, MOE nucleotides present in respective duplexes are showing the structure of A-form and the PS-DNA nucleotides resemble the structure of B-form helix with respect to some of the helical parameters. Free energy calculations suggest that the oligomer, which contains LNA binds to the RNA strongly than other modifications as shown in experimental results. The MOE modified nucleotide, which although had a lower binding affinity but higher solvent accessible surface area (SASA) compared to the other modifications, may be influencing the toxicity and hence may be used it in Mipomersen, the second antisense molecule which is approved by FDA. Communicated by Ramaswamy H. Sarma.

RNA dependent RNA polymerase (RdRP) from positive-stranded RNA viruses has always been a hot target for designing of new drugs. Major class of drugs that are targeted against RdRP are nucleotide analogues. Extensive docking and molecular dynamics study describing the binding of natural nucleotides (NTPs) and its analogues leading to significant structural variation in the RdRP has been presented here. RdRP simulations in its apo, NTP-bound, and analogue-bound form have been performed. Nucleotide analogues included in this study were, favipiravir, galidesivir, lamivudine, ribavirin, remdesivir and sofosbuvir. The conformational flexibility of the RdRP molecule has been explored using principal component (PCA) and Markov state modeling (MSM) analysis. PCA inferred the presence of correlated motions among the conserved motifs of RdRP. Inter-domain distances between the finger and thumb subdomain flanking the nascent RNA template entry site sampled open and closed conformations. The ligand and template binding motifs F and G showed negatively correlated motions. K551, R553, and R555, a part of motif F appear to form strong interactions with the ligand molecules. R836, a primer binding residue was observed to strongly bind to the analogues. MSM analysis helped to extract statistically distinct conformations explored by the RdRP. Ensemble docking of the ligands on the Markov states also suggested the involvement of the above residues in ligand interactions. Markov states obtained clearly demarcated the open/closed conformations of the template entry site. These observations on residues from the conserved motifs involved in binding to the ligands may provide an insight into designing new inhibitors.Communicated by Ramaswamy H. Sarma.

cWnt-signalling plays a crucial role in stem cell maintenance and tissue homeostasis. Secreted frizzled-related proteins(SFRP), Wnt inhibitors consist of the N-terminal cysteine rich domain(CRD) and the C-terminal netrin(NTR) domain. SFRP1 binds to the Wnt ligands and frizzled receptors(FZ) either through its SFRP1CRD or through its SFRP1Netrin domains; however, very little is known on these binding affinities. Here, we attempted to understand the interactions and binding affinities of SFRP1-Wnt5B, SFRP1-FZ(2, 37) and Wnt5B-FZ(2, 37) that are mainly expressed in murine hair follicle stem cells. SFRP1CRD, SFRP1Netrin, Wnt5B and FZ(2, 37) structures were built using homology modelling, followed by their molecular dynamics simulations. SFRP1CRD showed lower fluctuation when in complex with FZ2, FZ3 and FZ7 and Wnt5B as compared to SFRP1Netrin using RMSF and RMSD. However, free energy showed SFRP1Netrin was energetically more stable than SFRP1CRD. SFRP1Netrin formed more number of interactions with FZ as compared to SFRP1CRD. Importantly, SFRP1Netrin favoured binding to the FZ receptors(FZ3 FZ7 FZ2) as compared to Wnt5B ligand. Conversely, the SFRP1CRD showed more affinity towards the Wnt5B ligand as compared to FZ receptors. Wnt5B showed the best binding affinity with FZ3 followed by SFRP1CRD and SFRP1Netrin. Therefore, SFRP1Netrin can bind to the FZ3 with higher binding affinity and may inhibit non-canonical Wnt-signalling pathway. Our study provides the comprehensive information on the binding affinities among the Wnt5B, SFRP1CRD/Netrin and FZ(2, 37). Thus, this information might also help in designing novel strategies to inhibit aberrant Wnt-signalling.Communicated by Ramaswamy H. Sarma.

Antisense technology has been developed as the next generation drug discovery methodology by which unwanted gene expression can be inhibited by targeting mRNA specifically with antisense oligonucleotides. The computational studies of antisense modifications based on phosphorothioate (PS), methoxyethyl (MOE), locked nucleic acids (LNA) may help to design better novel modifications. In the present study, five novel LNA based modifications have been proposed. The conformational search has been done to identify the most stable and alternative stable conformations. The geometry optimization followed by single point energy calculation has been done at B3LYP/6-31G(d,p) level for gas phase and B3LYP/6-311G(d,p) level for the solvent phase for all modifications at monomer as well as base pair level. The electronic properties and the quantum chemical descriptors of the antisense modifications were derived and compared. The local and global reactivity descriptors, such as hardness, chemical potential, electronegativity, electrophilicity index, Fukui function all were calculated at the DFT level for the optimized geometries. A comparison of global reactivity descriptors confirmed that LNA based modifications are the most reactive modifications. They may form a stable duplex when bound to complementary nucleotides, compared to other modifications. Therefore, we are proposing that one of our proposed antisense modifications (A3) may show strong binding to the complementary nucleotide as LNA and may also show reduced toxic effects like MOE. The base pair studies may help us to understand the extent to which our proposed modifications can form standard Watson-Crick base pairing required for oligomer duplexes. This computational approach may be very useful to propose novel modifications prior to undergoing synthesis experimentally in the area of antisense or RNAi technology.

RNA dependent RNA polymerase (RdRP) from positive stranded RNA viruses has always been a hot target for designing of new drugs as it is responsible for viral replication. The major class of drugs that are targeted against RdRP are nucleotide analogues. An extensive docking and molecular dynamics study describing the role of natural nucleotides (NTPs) and its analogues in imparting an inhibitory effect on the RdRP has been presented here. RdRP simulations in its apo, NTP-bound and analogue-bound form have been performed for a cumulative time of 1.9 μs. The conformational flexibility of the RdRP molecule was explored using Principal Component Analysis (PCA) and Markov State Modeling (MSM) Analysis. PCA inferred the presence of correlated motions along the conserved motifs of the RdRP. The ligand binding motif F and template binding motif G showed motions that are negatively correlated with one another. LYS 551, ARG 553 and ARG 555 which are a part of the motif F appear to form strong interactions with the ligand molecules. ARG 836, a primer binding residue was observed to strongly bind to the nucleotide analogues. The MSM analysis helped to observe different conformational states explored by the RdRP. The ensemble docking of the ligands on the Markov states suggested the involvement of the above residues in ligand interactions. The Markov states obtained clearly demarcated the open and closed conformations. The closed states were observed to have more favorable docking of the ligands. MSM analysis predicted a probable inhibitory mechanism involving the closing of the template entry site by reduction in the distance between the flanking finger and thumb subdomain.

Antisense technology has been developed as the next generation drug discovery methodology by which unwanted gene expression can be inhibited by targeting mRNA specifically with antisense oligonucleotides. It has been observed that a good number of these molecules entered into clinical trials at a faster rate and some of them got approved. The computational studies of antisense modifications based on phosphorothioate (PS), methoxyethyl (MOE), locked nucleic acids (LNA) may help to design better novel modifications. In the present study, newer LNA based modifications have been proposed. The conformational search and density functional theory (DFT) calculations have been used to investigate the quantum chemical parameters of PS, LNA, MOE, and novel LNA based proposed modifications. The conformational search has been done to identify the most and alternative stable conformations. The geometry optimization followed by single point energy calculation has been done at B3LYP/6-31G(d,p) level for gas phase and B3LYP/6-311G(d,p) level for the solvent phase of all modifications. The electronic properties and the quantum chemical descriptors for the frontier molecular orbitals of all the antisense modifications were derived and compared. The local and global reactivity descriptors, such as hardness, chemical potential, electronegativity, electrophilicity index, Fukui function calculated at DFT level for the optimized geometries. These are used for understanding the reactive nature and reactive sites of the modifications. A comparison of global reactivity descriptors confirmed that LNA based modifications are the most reactive modifications and prone to the chemical reactions. It may form stable duplex when it is bound to complementary nucleotides, compared to other modifications. Therefore, we are proposing that one of our proposed antisense modification (A3) may show strong binding to the complementary nucleotide as LNA and may also show reduced toxic effects like MOE.

The novel coronavirus is known to enter the cell by binding to the human transmembrane protein Angiotensin-Converting Enzyme 2 (ACE2). The S(Spike)-glycoprotein of the SARS-CoV-2 forms a complex with the ACE2. Thus, the S-glycoprotein is one of the hot targets, as it forms the first line of contact between the virus and the human cell. Drug repurposing would help in identifying drugs that are safe and have no or fewer side effects. Hence, in addition to the Food and Drug Administration (FDA) approved molecules the compounds from natural sources were also considered. The current study includes docking and simulations of the FDA approved molecules and phytochemicals from Indian medicinal plants, targeting the ACE2-Spike protein complex. Rutin DAB10 and swertiapuniside were obtained as the top-ranked drugs from these two databases, respectively. The molecular dynamics simulations of ligand-free, rutin DAB10-bound, and swertiapuniside-bound ACE2-Spike complex revealed crucial ACE2-Spike interface residues forming strong interactions with the two ligands molecules. This may infer, that they may affect the ACE2 and spike binding. The conformational flexibility in the drug-binding pocket was captured using the RMSD-based clustering of the ligand-free simulations. An ensemble docking was performed wherein the two databases were docked on each of the representatives of ACE2-Spike obtained through clustering. The potential phytochemicals identified belonged to Withania somnifera, Swertia chirayita, Tinospora cordifolia, Andrographis paniculata, Piper longum, and Azadirachta indica. The FDA molecules identified were rutin DAB10, fulvestrant, cefoperazone acid, escin, chlorhexidine diacetate, echinacoside, capreomycin sulfate, and elbasvir.

The efforts towards developing a potential drug against the current global pandemic, COVID-19, has increased in the past few months. Drug development strategies to target the RNA dependent RNA polymerase (RdRP) are being tried worldwide. The gene encoding this protein, is known to be conserved amongst positive strand RNA viruses. This enables an avenue to repurpose the drugs designed against earlier reported inhibitors of RdRP. One such strong inhibitor is remdesivir which has been used against EBOLA infections. The binding of remdesivir to RdRP of SARS-CoV-2 has been studied using the classical molecular dynamics and ensemble docking approach. A comparative study of the simulations of RdRP in the apo and remdesivir-bound form revealed blocking of the template entry site in the presence of remdesivir. The conformation changes leading to this event were captured through principal component analysis. The conformational and thermodynamic parameters supported the experimental information available on the involvement of crucial arginine, serine and aspartate residues belonging to the conserved motifs in RdRP functioning. The catalytic site comprising of SER 759, ASP 760, and ASP 761 (SDD) was observed to form strong contacts with remdesivir. The significantly strong interactions of these residues with remdesivir may infer the latter’s binding similar to the normal nucleotides thereby remaining unidentified by the exonuclease activity of RdRP. The ensemble docking of remdesivir too, comprehended the involvement of similar residues in interaction with the inhibitor. This information on crucial interactions between conserved residues of RdRP with remdesivir through in-silico approaches may be useful in designing inhibitors.

Lead optimization is one of the crucial steps in the drug discovery pipeline. After identifying the lead molecule and obtaining its 2D geometry, understanding the best conformation it would attain in 3D still remains one of the most challenging steps in drug discovery. There have been multiple methods and algorithms that are directed toward achieving best conformation for the lead molecules. TANGO focuses on conformation generation and its optimization using semiempirical energy calculations. The conformation generation is based on torsion angle rotation of the exocyclic bonds. The energy calculations are performed using MOPAC. The unique feature of this tool lies in the implementation of Message Passing Interface (MPI) for conformation generation and semiempirical-based optimization. A well-defined architecture handling the input and output generation has been used. The master and slave approach to handle operations involved in torsion angle rotation and energy calculations has helped in load balancing the process of conformation generation. The benchmarking results suggest that TANGO scales significantly well across eight nodes with each node utilizing 16 cores. This tool may prove to very useful in high throughput generation of semiempirically optimized small molecule conformations. The use of semiempirical methods for optimization generates a conformational ensemble thereby helping to obtain stable and alternate stable conformers for a given ligand molecule. © 2018 Wiley Periodicals, Inc.

In the present study, five novel LNA based antisense modifications have been proposed. A conformational search was carried out using TANGO, followed by geometry optimization using MOPAC. Based on their electronic energies the most stable conformation for each modification was identified. Further, DFT based full geometry optimization on the most stable conformations at the gas phase B3LYP/6-31G(d,p) using a Gaussian03 and single point energy calculations on the optimized structures at the solvent phase B3LYP/6-311G(d,p) level of theory were done to derive their quantum chemical descriptors using the Gaussian09. A comparison of global reactivity descriptors confirmed that the LNA based modifications were the most reactive. Base-pair stability was recorded by observing the binding energies and base-pairing conformations of modified GC base pairs at the B3LYP/6-311G(d,p) level of theory. Molecular dynamics simulations have been performed at the oligomer duplex level by incorporating individual modifications on 20-mer RNA-RNA duplexes using AMBER16. Free energy calculations of duplex structures suggested that incorporation of A2 modification into the RNA-RNA duplex increased the duplex binding affinity similar to LNA. Whereas, the A3 modification showed less binding compared to LNA but improved binding compared to MOE. This computational approach using quantum chemical methods may be very useful to propose better modifications than the existing ones before performing the experiments in the area of antisense technology.

Alzheimer's disease (AD) is a multifactorial brain disorder that involves several pathophysiological events, like amyloidogenesis, acetylcholine deficit, neuroinflammation, cellular oxidative stress and dysfunctional autophagy. Hence, to cure AD, it is necessary to target multiple mechanisms involved in the development and progression of AD. This study reports a novel methyl-substituted 3-acetylcoumarin thiosemicarbazone (ACT) derivative, viz. [(2E)-N-methyl-2-[1-(2-oxo-2H-1-benzopyran-3-yl) ethylidene] hydrazine-1-carbothioamide], (ACMT), and the protective effect of these compounds towards acetylcholinesterase activity, inflammation and autophagy induction. The crystal structure of ACMT is solved by using single-crystal X-ray diffraction. The molecular docking studies showed that the methyl substitution of 3-acetylcoumarin thiosemicarbazone modulates its hydrophobic and hydrogen-bonding interactions with the active site of acetylcholinesterase enzyme (AChE), resulting in a better inhibition of AChE activity. Methyl-substitution of 3-acetylcoumarin thiosemicarbazone also causes better peptide aggregation inhibition as compared to the parent compound. Further, the anti-inflammatory activity of these compounds in BV-2 microglial cells was determined. Data showed that the incorporation of methyl substitution of 3-acetylcoumarin thiosemicarbazone enhances the potency of ACT to induce autophagy in SH-SY5Y neuroblastoma cells. ACT and ACMT also rescue the rough eye phenotype at 20 μM concentration in GMR-Aβ Drosophila melanogaster model of AD.

Background The distinct functional effects of the replication-dependent histone H2A isoforms have been demonstrated; however, the mechanistic basis of the non-redundancy remains unclear. Here, we have investigated the specific functional contribution of the histone H2A isoform H2A1H, which differs from another isoform H2A2A3 in the identity of only three amino acids. Results H2A1H exhibits varied expression levels in different normal tissues and human cancer cell lines (H2A1C in humans). It also promotes cell proliferation in a context-dependent manner when exogenously overexpressed. To uncover the molecular basis of the non-redundancy, equilibrium unfolding of recombinant H2A1H-H2B dimer was performed. We found that the M51L alteration at the H2A–H2B dimer interface decreases the temperature of melting of H2A1H-H2B by ~ 3 °C as compared to the H2A2A3-H2B dimer. This difference in the dimer stability is also reflected in the chromatin dynamics as H2A1H-containing nucleosomes are more stable owing to M51L and K99R substitutions. Molecular dynamic simulations suggest that these substitutions increase the number of hydrogen bonds and hydrophobic interactions of H2A1H, enabling it to form more stable nucleosomes. Conclusion We show that the M51L and K99R substitutions, besides altering the stability of histone–histone and histone–DNA complexes, have the most prominent effect on cell proliferation, suggesting that the nucleosome stability is intimately linked with the physiological effects observed. Our work provides insights into the molecular basis of the non-redundancy of the histone H2A isoforms that are being increasingly reported to be functionally important in varied physiological contexts.

Sickle cell disease is an inherited disease caused by point mutation in hemoglobin (β-globin gene). Under oxygen saturation, sickle hemoglobin form polymers, leading to rigid erythrocytes. The transition of the blood vessels is altered and initiated by the adhesion of erythrocytes, neutrophils and endothelial cells. Sickle Hemoglobin (HbS) polymerization is a major cause in red blood cells (RBC), promoting sickling and destruction of RBCs. Isoquercitrin, a medicinal bioactive compound found in various medicinal plants, has multiple health benefits. The present study examines the potential of isoquercitrin as an anti-sickle agent, showing a significant decrease in the rate of polymerization as well as sickling of RBCs. Isoquercitrin-induced graded alteration in absorbance and fluorescence of HbS, confirmed their interaction. A negative value of Δ

The conversion of prion protein from normal to scrapie followed by the aggregation and deposition of this scrapie form leads to various neurodegenerative diseases. A few studies carried out by researchers suggest that E219K prion mutant (glutamate to lysine mutation at residue position 219) is more stable than wild type protein. However a similar point mutation E200K (glutamate to lysine mutation at residue position 200) is pathogenic. In this study we have carried out detailed atomistic simulation of the wild type, pathogenic mutant E200K and E219K mutant which provides more stability. The aim of the study was to detect the early structural changes present in all the three variants which might be responsible for the stability or for their conversion from PrPC to PrPSc. MSM based analyses have been carried out to find out the differences between WT, E200K and E219K systems. Markov state model (MSM) analysis was able to predict the intermediate states which helped to understand the effect of same mutation at two different locations. The MSM analysis was able to show that the extra stability of E219K mutant may be a result of the increase in number of native contacts, strong salt bridges and less random motions. While pathogenicity of E200K mutant can be attributed to loss of some crucial salt-bridge interactions, increased random motions between helix 2 and helix 3.

In this current age of data-driven science, perceptive research is being carried out in the areas of genomics, network and metabolic biology, human, animal, organ and tissue models of drug toxicity, witnessing or capturing key biological events or interactions for drug discovery. Drug designing and repurposing involves understanding of ligand orientations for proper binding to the target molecules. The crucial requirement of finding right pose of small molecule in ligand–protein complex is done using drug docking and simulation methods. The domains of biology like genomics, biomolecular structure dynamics, and drug discovery are capable of generating vast molecular data in range of terabytes to petabytes. The analysis and visualization of this data pose a great challenge to the researchers and needs to be addressed in an accelerated and efficient way. So there is continuous need to have advanced analytics platform and algorithms which can perform analysis of this data in a faster way. Big data technologies may help to provide solutions for these problems of molecular docking and simulations.

Polymerization of hemoglobin S is a major cause of morbidity and mortality in sickle cell disease, which leads to sickling and destruction of red blood cell. Alizarin, a bioactive compound from Rub...

Background The distinct functional effects of the replication-dependent histone H2A isoforms have been demonstrated; however, the mechanistic basis of the non-redundancy remains unclear. Here, we have investigated the specific functional contribution of the histone H2A isoform H2A1H, which differs from another isoform H2A2A3 in the identity of only three amino acids. Results H2A1H exhibits varied expression levels in different normal tissues and human cancer cell lines (H2A1C in humans). It also promotes cell proliferation in a context-dependent manner when exogenously overexpressed. To uncover the molecular basis of the non-redundancy, equilibrium unfolding of recombinant H2A1H-H2B dimer was performed. We found that the M51L alteration at the H2A–H2B dimer interface decreases the temperature of melting of H2A1H-H2B by ~ 3 °C as compared to the H2A2A3-H2B dimer. This difference in the dimer stability is also reflected in the chromatin dynamics as H2A1H-containing nucleosomes are more stable owing to M51L and K99R substitutions. Molecular dynamic simulations suggest that these substitutions increase the number of hydrogen bonds and hydrophobic interactions of H2A1H, enabling it to form more stable nucleosomes. Conclusion We show that the M51L and K99R substitutions, besides altering the stability of histone–histone and histone–DNA complexes, have the most prominent effect on cell proliferation, suggesting that the nucleosome stability is intimately linked with the physiological effects observed. Our work provides insights into the molecular basis of the non-redundancy of the histone H2A isoforms that are being increasingly reported to be functionally important in varied physiological contexts. Electronic supplementary material The online version of this article (doi:10.1186/s13072-017-0155-z) contains supplementary material, which is available to authorized users.

Protein folding is a multi-micro second time scale event and involves many conformational transitions. Crucial conformational transitions responsible for biological functions of biomolecules are difficult to capture using current state-of-the-art molecular dynamics (MD) simulations. Protein folding, being a stochastic process, witnesses these transitions as rare events. Many new methodologies have been proposed for observing these rare events. In this work, a temperature-aided cascade MD is proposed as a technique for studying the conformational transitions. Folding studies for Engrailed homeodomain and Immunoglobulin domain B of protein A have been carried out. Using this methodology, the unfolded structures with RMSD of 20 Å were folded to a structure with RMSD of 2 Å. Three sets of cascade MD runs were carried out using implicit solvation, explicit solvation, and charge updation scheme. In the charge updation scheme, charges based on the conformation obtained are calculated and are updated in the topology file. In all the simulations, the structure of 2 Å was reached within a few nanoseconds using these methods. Umbrella sampling has been performed using snapshots from the temperature-aided cascade MD simulation trajectory to build an entire conformational transition pathway. The advantage of the method is that the possible pathways for a particular reaction can be explored within a short duration of simulation time and the disadvantage is that the knowledge of the start and end state is required. The charge updation scheme adds the polarization effects in the force fields. This improves the electrostatic interaction among the atoms, which may help the protein to fold faster.

The Ras family of proteins is known to play an important role in cellular signal transduction. The oncoprotein Ras is also found to be mutated in ∼90% of the pancreatic cancers, of which G12V, G13V, A59G and Q61L are the known hot-spot mutants. These ubiquitous proteins fall in the family of G-proteins, and hence switches between active GTP bound and inactive GDP bound states, which is hindered in most of its oncogenic mutant counterparts. Moreover, Ras being a GTPase has an intrinsic property to hydrolyze GTP to GDP, which is obstructed due to mutations and lends the mutants stuck in constitutively active state leading to oncogenic behavior. In this regard, the present study aims to understand the dynamics involved in the hot-spot mutant A59G-Ras using long classical MD simulations (∼10µs) and comparing the same with its wild-type counterpart. Advanced analytics using Markov State Model (MSM) based approach has been deployed to comparatively understand the transition path for the wild-type and mutant systems. Roles of crucial residues like Tyr32, Gln61 and Tyr64 have also been established using multivariate PCA analyses. Furthermore, this multivariate PCA analysis also provides crucial features which may be used as reaction coordinates for biased simulations for further studies. The absence of formation of pre-hydrolysis network is also reported for the mutant conformation, using the distance-based analyses (between crucial residues) of the conserved regions. The implications of this study strengthen the hypothesis that the disruption of the pre-hydrolysis network in the mutant A59G ensemble might lead to permanently active oncogenic conformation in the mutant conformers.

Lead optimization is one of the crucial steps in the drug discovery pipeline. After identifying the lead molecule and obtaining its 2D geometry, understanding the best conformation it would attain in 3D still remains one of the most challenging steps in drug discovery. There have been multiple methods and algorithms that are directed toward achieving best conformation for the lead molecules. TANGO focuses on conformation generation and its optimization using semiempirical energy calculations. The conformation generation is based on torsion angle rotation of the exocyclic bonds. The energy calculations are performed using MOPAC. The unique feature of this tool lies in the implementation of Message Passing Interface (MPI) for conformation generation and semiempirical-based optimization. A well-defined architecture handling the input and output generation has been used. The master and slave approach to handle operations involved in torsion angle rotation and energy calculations has helped in load balancing the process of conformation generation. The benchmarking results suggest that TANGO scales significantly well across eight nodes with each node utilizing 16 cores. This tool may prove to very useful in high throughput generation of semiempirically optimized small molecule conformations. The use of semiempirical methods for optimization generates a conformational ensemble thereby helping to obtain stable and alternate stable conformers for a given ligand molecule. © 2018 Wiley Periodicals, Inc.

Nucleosome assembly protein 1 (NAP1) is a histone chaperone that exchanges histone H2A-H2B dimer from chromatin templates. Studies with yeast NAP1 (yNAP1) have revealed its existence as multiple oligomeric species in solution. Here, rat NAP1 (rNAP1), which is 98% identical to the human NAP1 (hNAP1) was used as a model to characterize the oligomeric structures of this protein in higher eukaryotes. Gel filtration chromatography and Dynamic light scattering of recombinant rNAP1 indicated that the protein exists as a complex mixture of multimeric species even at 500 mM ionic strength. The solution-state complexity remains unchanged even at higher ionic strengths. Equilibrium unfolding (ΔG 14.6 kcal mol− 1) shows that rNAP1, both dimeric and oligomeric, follow the two-state model of unfolding with no detectable intermediates. Homology modelling suggests that rat and yeast NAP1 share an overall similar structure with conserved domains. However, dissimilar substitutions like threonine and lysine with glycine in the β-hairpin involved in oligomerization, possibly leads to the observed differences in the oligomerization propensity of the two proteins. Molecular dynamic simulation (MDS) of the two structures also revealed that rNAP1 dimer is more stable owing to the extensive hydrogen bonding in comparison to yNAP1. Further, in vitro kinase assay showed that the phosphorylation of rNAP1 favors oligomerization with no effect on its histone binding capacity. Our results clearly suggest that there are differences in the in-solution behavior of rNAP1 compared to yNAP1 which may have in vivo functional implications for the regulation of these complexes during chromatin assembly and rearrangement.

Additional file 1: Figure S1. Multiple alignment of all the H2A protein sequences in rat. Figure S2. RP-HPLC chromatogram of histones isolated from the rat liver tissue. Figure S3. Unique peptides identified for the H2A isoforms. Figure S4. Real-time PCR of H2A isoforms in the normal vs tumor liver tissues. Figure S5. H2A.1 and H2A.2 isoforms in the CL44 and CL38 cells. Figure S6. Migration and cell proliferation upon overexpression of the histone H2A isoforms. Figure S7. Sequence comparison of H2A isoforms. Figure S8. Approach for equilibrium unfolding analysis of histone dimers. Figure S9. Guanidine chloride induced denaturation of H2A-H2B dimer. Figure S10. RMSD of MDS. Figure S11. Primers.

Bioprospecting of natural molecules is essential to overcome serious environmental issues and pesticide resistance in insects. Here we are reporting insights into insecticidal activity of a plant natural phenol. In silico and in vitro screening of multiple molecules supported by in vivo validations suggested that caffeic acid (CA) is a potent inhibitor of Helicoverpa armigera gut proteases. Protease activity and gene expression were altered in CA-fed larvae. The structure-activity relationship of CA highlighted that all the functional groups are crucial for inhibition of protease activity. Biophysical studies and molecular dynamic simulations revealed that sequential binding of multiple CA molecules induces conformational changes in the protease(s) and thus lead to a significant decline in their activity. CA treatment significantly inhibits the insect's detoxification enzymes, thus intensifying the insecticidal effect. Our findings suggest that CA can be implicated as a potent insecticidal molecule and explored for the development of effective dietary pesticides.

A new strategy toward biologically active enantiomerically pure benzomorphan analogues is described. The key steps in the synthesis are the l -proline catalyzed asymmetric α-aminooxylation of an aldehyde and the titanium tetrachloride promoted intramolecular oxa-Pictet–Spengler cyclization of (4 R )-2-(bromomethyl)-4-(2,5-dimethoxybenzyl)-1,3-dioxolane. In the intramolecular oxa-Pictet–Spengler cyclization, cis -pyran 8a (71%) formed over the trans -pyran 8b (14%). Computational modeling studies provided an insight into the stereoselectivity of the products. Docking studies of benzomorphan derivatives indicated that compound 6c had the best binding efficiency, and that it formed extensive hydrogen bonding with TYR148 on transmembrane (TM) helix 3 and HIS297 on TM6 of the μ-opioid receptor, which belong to the G-protein coupled receptor super family.

The long perceived notion that G-Protein Coupled Receptors (GPCRs) function in monomeric form has recently been changed by the description of a number of GPCRs that are found in oligomeric states. The mechanism of GPCR oligomerization, and its effect on receptor function, is not well understood. In the present study, coarse grained molecular dynamics (CGMD) approach was adopted for studying the self-assembly process of the human GPCR, @b2-adrenergic receptor (@b2-AR), for which several experimental evidences of the dimerization process and its effect on cellular functions are available. Since the crystal structure of @b2-AR lacks the third intracellular loop, initially it was modelled and simulated using restrained MD in order to get a stable starting conformation. This structure was then converted to CG representation and 16 copies of it, inserted into a hydrated lipid bilayer, were simulated for [email protected] using the MARTINI force field. At the end of [email protected], oligomers of @b2-AR were found to be formed through the self-assembly mechanism which were further validated through various analyses of the receptors. The lipid bilayer analysis also helped to quantify this assembly mechanism. In order to identify the domains which are responsible for this oligomerization, a reverse transformation of the CG system back to all-atom structure and simulated annealing run were carried out at the end of [email protected] CGMD run. Analysis of the all-atom dimers thus obtained, revealed that TM1/TM1, H8/H8, TM1/TM5 and TM6/TM6 regions formed most of the dimerization surfaces, which is in accordance with some of the experimental observations and recent simulation results.

Ligand recognition in purine riboswitches is a complex process requiring different levels of conformational changes. Recent efforts in the area of purine riboswitch research have focused on ligand analogue binding studies. In the case of the guanine xanthine phosphoribosyl transferase (xpt) riboswitch, synthetic analogues that resemble guanine have the potential to tightly bind and subsequently influence the genetic expression of xpt mRNA in prokaryotes. We have carried out 25 ns Molecular Dynamics (MD) simulation studies of the aptamer domain of the xpt G-riboswitch in four different states: guanine riboswitch in free form, riboswitch bound with its cognate ligand guanine, and with two guanine analogues SJ1 and SJ2. Our work reveals novel interactions of SJ1 and SJ2 ligands with the binding core residues of the riboswitch. The ligands proposed in this work bind to the riboswitch with greater overall stability and lower root mean square deviations and fluctuations compared to guanine ligand. Reporter gene assay data demonstrate that the ligand analogues, upon binding to the RNA, lower the genetic expression of the guanine riboswitch. Our work has important implications for future ligand design and binding studies in the exciting field of riboswitches.