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Pyridoxal kinase (PDXK) is a vitamin B6-dependent transferase enzyme encoded by the PDXK gene, crucial for leukemic cell proliferation. Disruption of its activity causes altered metabolism and reduced levels of nucleotides and polyamines. PDXK and pyridoxal 5'-phosphate (PLP) are overexpressed in various carcinomas, making them promising targets for drug design against cancer. Targeting PDXK may hold promise as a therapeutic approach for cancer treatment. This study focused on discovering potential inhibitors that could selectively interrupt the binding of pyridoxal phosphate (PLP) to pyridoxal kinase (PDXK). A commercially available library of 7,28,747 natural and druglike compounds was virtually screened using a molecular docking approach to target the substrate binding pocket of PDXK. Six promising inhibitors were identified, and all-atom molecular dynamics simulations were conducted on the PDXK-ligand complexes for 100 ns to assess their binding conformational stability. The simulation results indicated that the binding of ZINC095099376, ZINC01612996, ZINC049841390, ZINC095098959, ZINC01482077, and ZINC03830976 induced a slight structural change and stabilized the PDXK structure. This analysis provided valuable information about the critical residues involved in the PDXK-PLP complex formation and can be utilized in designing specific and effective PDXK inhibitors. According to this study, these compounds could be developed as anticancer agents targeting PDXK as a potential candidate for further study.Communicated by Ramaswamy H. Sarma.

The Mast/Stem cell growth factor receptor Kit (c-Kit), a Proto-oncogene c-Kit, is a tyrosine-protein kinase involved in cell differentiation, proliferation, migration, and survival. Its role in developing certain cancers, particularly gastrointestinal stromal tumors (GISTs) and acute myeloid leukemia (AML), makes it an attractive therapeutic target. Several small molecule inhibitors targeting c-Kit have been developed and approved for clinical use. Recent studies have focused on identifying and optimizing natural compounds as c-Kit inhibitors employing virtual screening. Still, drug resistance, off-target side effects, and variability in patient response remain significant challenges. From this perspective, phytochemicals could be an important resource for discovering novel c-Kit inhibitors with less toxicity, improved efficacy, and high specificity. This study aimed to uncover possible c-Kit inhibitors by utilizing a structure-based virtual screening of active phytoconstituents from Indian medicinal plants. Through the screening stages, two promising candidates, Anilinonaphthalene and Licoflavonol, were chosen based on their drug-like features and ability to bind to c-Kit. These chosen candidates were subjected to all-atom molecular dynamics (MD) simulations to evaluate their stability and interaction with c-Kit. The selected compounds Anilinonaphthalene from Daucus carota and Licoflavonol from Glycyrrhiza glabra showed their potential to act as selective binding partners of c-Kit. Our results suggest that the identified phytoconstituents could serve as a starting point to develop novel c-Kit inhibitors for developing new and effective therapies against multiple cancers, including GISTs and AML. The use of virtual screening and MD simulations provides a rational approach to discovering potential drug candidates from natural sources.Communicated by Ramaswamy H. Sarma.

Ribosomal protein S6 kinase 1 (S6K1), commonly known as P70-S6 kinase 1 (p70S6), is a key protein kinase involved in cellular signaling pathways that regulate cell growth, proliferation, and metabolism. Its significant role is reported in the PIK3/mTOR signaling pathway and is associated with various complex diseases, including diabetes, obesity, and different types of cancer. Due to its involvement in various physiological and pathological conditions, S6K1 is considered as an attractive target for drug design and discovery. One way to target S6K1 is by developing small molecule inhibitors that specifically bind to its ATP-binding site, preventing its activation and thus inhibiting downstream signaling pathways necessary for cell growth and survival. In this study, we have conducted a multitier virtual screening of a pool of natural compounds to identify potential S6K1 inhibitors. We performed molecular docking on IMPPAT 2.0 library and selected top hits based on their binding affinity, ligand efficiency, and specificity towards S6K1. The selected hits were further assessed based on different filters of drug-likeliness where two compounds (Hecogenin and Glabrene) were identified as potential leads for S6K1 inhibition. Both compounds showed appreciable affinity, ligand efficiency and specificity towards S6K1 binding pocket, drug-like properties, and stable protein-ligand complexes in molecular dynamics (MD) simulations. Finally, our study has suggested that Hecogenin and Glabrene can be potential S6K1 inhibitors which are presumably implicated in the therapeutic management of associated diseases such as diabetes, obesity, and varying types of cancer.Communicated by Ramaswamy H. Sarma.

Spleen tyrosine kinase (SYK) is a non-receptor tyrosine kinase that plays an essential role in signal transduction across different cell types. In the context of allergy and autoimmune disorders, it is a crucial regulator of immune receptor signaling in inflammatory cells such as B cells, mast cells, macrophages, and neutrophils. Developing SYK kinase inhibitors has gained significant interest for potential therapeutic applications in neurological and cancer-related conditions. The clinical use of the most advanced SYK inhibitor, Fostamatinib, has been limited due to its unwanted side effects. Thus, a more targeted approach to SYK inhibition would provide a more comprehensive treatment window. In this study, we used a virtual screening approach to identify potential SYK inhibitors from natural compounds from the IMPPAT database. We identified two compounds, Isolysergic acid and Michelanugine, which showed strong affinity and specificity for the SYK binding pocket. All-atom molecular dynamics (MD) simulations were also performed to explore the stability, conformational changes, and interaction mechanism of SYK in complexes with the identified compounds. The identified compounds might have the potential to be developed into promising SYK inhibitors for the treatment of various diseases, including autoimmune disorders, cancer, and inflammatory diseases. This work aims to identify potential phytochemicals to develop a new protein kinase inhibitor for treating advanced malignancies by providing an updated understanding of the role of SYK.Communicated by Ramaswamy H. Sarma.

Raf proto-oncogene serine/threonine kinase 1 (RAF1 or c-Raf) is a serine/threonine protein kinase crucial in regulating cell growth, differentiation, and survival. Any disruption or overexpression of RAF1 can result in neoplastic transformation and other disorders such as cardiomyopathy, Noonan syndrome, leopard syndrome, etc. RAF1 has been identified as a potential therapeutic target in drug development against various complex diseases, including cancer, due to its remarkable role in disease progression. Here, we carried out a multitier virtual screening study involving different in-silico approaches to discover potential inhibitors of RAF1. After applying the Lipinski rule of five, we retrieved all phytocompounds from the IMPPAT database based on their physicochemical properties. We performed a molecular docking-based virtual screening and got top hits with the best binding affinity and ligand efficiency. Then we screened out the selected hits using the PAINS filter, ADMET properties, and other druglike features. Eventually, PASS evaluation identifies two phytocompounds, Moracin C and Tectochrysin, with appreciable anti-cancerous properties. Finally, all-atom molecular dynamics simulation (MDS) followed by interaction analysis was performed on the elucidated compounds in complex with RAF1 for 200 ns to investigate their time-evolution dynamics and interaction mechanism. Molecular mechanics Poisson-Boltzmann surface area (MM-PBSA) and Dynamical Cross-Correlation Matrix (DCCM) analyses then followed these results from the simulated trajectories. According to the results, the elucidated compounds stabilize the RAF1 structure and lead to fewer conformational alterations. The results of the current study indicated that Moracin C and Tectochrysin could serve as potential inhibitors of RAF1 after required validation.Communicated by Ramaswamy H. Sarma.

Tyrosine-protein kinase Lyn (LynK) has emerged as one of the most attractive therapeutic targets for cancer and diabetes. In this study, we used a multistep virtual screening process of natural compounds to discover potential inhibitors of LynK from the IMPPAT database. The primary filters were based on Lipinski rules, ADMET properties, and PAINS patterns. Then, binding affinities and interaction analyses were carried out for the high-affinity selectivity of the compounds towards LynK. Eventually, two natural compounds, Glabrene and Lactupicrin, were identified with high affinity and specificity for the LynK-binding pocket. Both compounds exhibited drug-like properties, as predicted by ADMET analysis and physicochemical parameters. The molecular dynamics (MD) simulation study revealed that these compounds bind to the ATP-binding pocket of LynK and interact with functionally significant residues with stability without inducing any significant structural changes to the protein. Ultimately, the identified compounds may be regarded as promising LynK inhibitors and can be used as lead molecules in the drug development against LynK-related diseases.Communicated by Ramaswamy H. Sarma.

Cyclin-dependent kinase 9 (CDK9) is a transcription-associated protein involved in controlling the cell cycle and is often deregulated in stress conditions. CDK9 is being studied as a well-known druggable target for developing effective therapeutics against a wide range of cancer, cardiac dysfunction and inflammatory diseases. Owing to the significance of CDK9 in the etiology of hematological and solid malignancies, its structure, biological activity, regulation and its pharmacological inhibition are being explored for therapeutic management of cancer. We employed a structure-based virtual high-throughput screening of bioactive compounds from the IMPPAT database to discover potential bioactive inhibitors of CDK9. The preliminary results were obtained from the Lipinski criteria, ADMET parameters and sorting compounds without any PAINS patterns. Subsequently, binding affinity and selectivity analyses were used to find effective CDK9 hits. This screening resulted in the identification of two natural compounds, Glabrene and Guggulsterone with high affinity and specificity for the CDK9 binding site. Both compounds exhibit drug-like characteristics, as projected by ADMET analysis, physicochemical data and PASS evaluation. Both compounds preferentially bind to the ATP-binding pocket of CDK9 and interact with functionally important residues. Further, the dynamics and consistency of CDK9 interaction with Glabrene and Guggulsteron were evaluated through all-atom molecular dynamic (MD) simulations which suggested the stability of both complexes. The results might be deployed to introduce novel CDK9 inhibitors that may treat life-threatening diseases, including cancer.Communicated by Ramaswamy H. Sarma.

Lung cancer (LC) is the leading cause of cancer-related deaths worldwide. Smoking has been identified as the main contributing cause of the disease's development. The study aimed to identify the key genes in small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC), the two major types of LC. Meta-analysis was performed with two datasets GSE74706 and GSE149507 obtained from Gene Expression Omnibus (GEO). Both the datasets comprised samples from cancerous and adjacent non-cancerous tissues. Initially, 633 differentially expressed genes (DEGs) were identified. To understand the underlying molecular mechanism of the identified genes, pathway enrichment, gene ontology (GO) and protein-protein interaction (PPI) analyses were done. A total of 9 hub genes were identified which were subjected to mutation study analysis in LC patients using cBioPortal. These   9 genes (i.e. AURKA , AURKB , KIF23 , RACGAP1 , KIF2C , KIF20A , CENPE , TPX2 and PRC1 ) have shown overexpression in LC patients and can be explored as potential candidates for prognostic biomarkers. TPX2 reported a maximum mutation of 4 % . This was followed with high throughput screening and docking analysis to identify the potential drug candidates following competitive inhibition of the AURKA-TPX2 complex. Four compounds, CHEMBL431482, CHEMBL2263042, CHEMBL2385714, and CHEMBL1206617 were identified. The results signify that the selected 9 genes can be explored as biomarkers in disease prognosis and targeted therapy. Also, the identified 4 compounds can be further analyzed as promising therapeutic candidates.Communicated by Ramaswamy H. Sarma.

Cyclin-dependent kinase 5 (CDK5) is a proline-directed serine-threonine protein kinase vital for neuronal cell cycle arrest and differentiation. It activates by binding with p35 and p39 and is important for the functioning of the nervous system. A growing body of evidence suggests that CDK5 contributes to the onset and progression of neurodegeneration and tumorigenesis and represents itself as a potential therapeutic target. Our research illustrates virtual screening of phytochemicals from the IMPPAT (Indian Medicinal Plants, Phytochemistry and Therapeutics) library to search for potential inhibitors of CDK5. Initially, the compounds from the parent library were filtered out via their physicochemical properties following the Lipinski rule of five. Then sequentially, molecular docking-based virtual screening, PAINS filter, ADMET, PASS analysis, and molecular dynamics (MD) simulation were done using various computational tools to rule out adversities that can cause hindrances in the identification of potential inhibitors of CDK5. Finally, two compounds were selected via the extensive screening showing significant binding with CDK5 ATP-binding pocket and ultimately were selected as potent ATP-competitive inhibitors of CDK5. Finally, we propose that the elucidated compounds Desmodin and Isopongachromene can be used further in the drug discovery process and act as therapeutics in the medical industry to treat certain complex diseases, including cancer and neurodegeneration.Communicated by Ramaswamy H. Sarma.

Hydroxychloroquine (HCQ), a quinoline based medicine is commonly used to treat malaria and autoimmune diseases such as rheumatoid arthritis. Since, human serum albumin (HSA) serves as excipient for vaccines or therapeutic protein drugs, it is important to understand the effect of HCQ on the structural stability of HSA. In this study, the binding mechanism of HCQ and their effect on stability of HSA have been studied using various spectroscopic techniques and molecular dynamic simulation. The UV-VIS results confirmed the strong binding of HCQ with HSA. The calculated thermodynamics parameters confirmed that binding is spontaneous in nature and van der Waals forces and hydrogen bonding are involved in the binding system which is also confirmed by molecular docking results. The steady-state fluorescence confirms the static quenching mechanism in the interaction system, which was further validated by time-resolved fluorescence. The synchronous fluorescence confirmed the more abrupt binding of HCQ with tryptophan residue of HSA compared to Tyr residue of HSA. Isothermal titration calorimetry (ITC) was done to validate the thermodynamics parameters of HSA-HCQ complex in one experiment, supporting the values obtained from the spectroscopic techniques. The circular dichroism (CD) demonstrated that the HCQ affected the secondary structure of HSA protein by reducing their α-helical content. The docking and molecular dynamic simulation results further helped in understanding the effect of HCQ on conformational changes of HSA. Overall, present work defined the physicochemical properties and interaction mechanism of HCQ with HSA that have extensively been elucidated by both in vitro and in silico approaches.Communicated by Ramaswamy H. Sarma.

Rho-associated protein kinase 1 (ROCK1) is a member of the AGC family which plays crucial roles in inflammatory diseases and cancer progression. Elevated expression of ROCK1 has been reported in multiple cancer types, and thus it has emerged as a potential drug target for cancer therapeutics. In this study, we performed a structure-based virtual screening of the natural compounds taken from the IMPPAT database to find some potential molecules as inhibitors of ROCK1. For the first step, we selected the compounds based on the Lipinski rule of five, and then we filtered them based on their ADMET properties and PAINS value. After this, other parameters like binding affinities, docking score, biological properties and selectivity were calculated to find appropriate hits against ROCK1. Finally, we identified two natural compounds, Isoononin and Candidissiol, with appreciable binding affinity and selectivity towards ROCK1. Furthermore, all-atom molecular dynamics simulations were carried out on ROCK1 with the elucidated compounds, which suggested stability throughout the simulated trajectories of 100 ns. Taken together, Isoononin and Candidissiol could be considered as potential inhibitors of ROCK1 for developing anticancer therapeutics.Communicated by Ramaswamy H. Sarma.

Fructosylation of proteins results in the formation of advanced glycation end-products (AGEs). A diet rich in fructose along with hyperglycemia can cause fructose mediated glycation (fructosylation) of proteins, which results in AGEs formation. Insulin is a peptide hormone that is glycated when exposed to carbohydrates such as glucose. In this study, we have analysed the interaction of insulin with fructose and biophysically characterized fructose modified insulin. In silico studies performed through molecular docking and molecular dynamics simulation revealed that fructose binds to insulin with strong affinity resulting in the formation of insulin-fructose complex. Fructosylation of insulin caused hyperchromicity, loss of intrinsic fluorescence, gain in AGEs specific fluorescence and elevated the carbonyl and fructosamine content. Enhanced thioflavin T fluorescence suggested the presence of fibrillar structures at higher concentrations of fructose. Electron microscopy revealed the formation of characteristic amorphous and amyloid like aggregates at lower and higher concentrations of fructose, respectively. These findings show that fructosylation of insulin causes AGEs production, aggregation and alters its gross structural integrity. These changes may reduce the biological activity of insulin that can aggravate conditions like type II diabetes mellitus.Communicated by Ramaswamy H. Sarma.

A respiratory pandemic known as coronavirus disease-19 (COVID-19) has created havoc since it emerged from Wuhan, China. COVID-19 is caused by a newly emerged SARS coronavirus (SARS-CoV) with increased pathogenicity named severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). Due to the lack of understanding of the mechanism of pathogenesis, an effective therapeutic option is unavailable. Epidemics described in Unani ancient literature include nazla-e-wabai and humma-e-wabai , and most of the symptoms of COVID-19 resemble nazla-e-wabai . Hence, in light of Unani literature, the treatment of COVID-19 can be managed with the composites prescribed in Unani medicine for nazla-e-wabai . In this study, a structure-based drug design approach was carried out to check the effectiveness of the pharmacologically active constituents of the Unani composites prescribed to treat nazla-e-wabai against SARS-CoV-2. We performed molecular docking of the active constituents of these composites against the main protease (M pro ), a potential drug target in SARS-CoV-2. Using detailed molecular docking analysis, Habb-ul-aas and Tabasheer were identified as potential inhibitors of SARS-CoV-2 M pro . The active constituents of both these composites bind to the substrate-binding pocket of SARS-CoV-2 M pro , forming interactions with key residues of the binding pocket. Molecular dynamics (MD) simulation suggested the binding of active constituents of Habb-ul-aas with SARS-CoV-2 M pro with a strong affinity as compared to the constituents of Tabasheer. Thus, this study sheds light on the use of these Unani composites in COVID-19 therapeutics.Communicated by Ramaswamy H. Sarma.

Alpha-crystallin ( α-crystallin) is an important eye protein having chaperone activity; its aggregation and precipitation are vital in cataract development. Polyethylene glycol-400 (PEG-400) is an important constituent of eye drops and artificial tears. The present study was targeted to study the binding of α-crystallin and PEG-400 employing multi spectroscopy, isothermal titration calorimetry (ITC) along with molecular modeling and docking approach. There was an apparent hypochromism in α-crystallin in the presence of varying PEG-400 concentrations; the binding constant obtained was 0.9 X 10 5 M -1 implying that strong binding is taking place between α-crystallin and PEG-400. Fluorescence spectroscopy suggested good binding of PEG-400 to α-crystallin with a binding constant ( K ) of 10 6 M -1 . Moreover, fluorescence quenching studies carried out at three different temperatures suggested α-crystallin-PEG-400 complex formation to be guided by combination of static and dynamic modes. Thermodynamic parameters suggested α-crystallin-PEG-400 complex formation is driven by van der Waals forces and hydrogen bonding, making it seemingly specific. Far UV-CD spectra revealed no shift in the peak implying no alterations in the secondary structure of α-crystallin upon PEG-400 binding further validating complex formation. In vitro assays were further entrenched by in silico assays. Molecular modeling was used to make the functionally active form of α-crystallin. A binding pocket located in the β chain was delineated by Prank Web; molecular docking showed binding of PEG-400 in this pocket. This study will give an insight into the binding of PEG-400 with α-crystallin and can serve as a rationale for the discovery of therapeutic molecules that can be used for the treatment of eye-related crystallin-directed diseases. HighlightsPEG-400 is a constituent of lubricant eye drops.Molecular modelling gave functionally active crystallin.Molecular docking showed PEG-400 in the binding pocket.Fluorescence binding revealed good bindingα-crystallin and PEG400.The α-crystallin-PEG-400 complex was guided by static and dynamic quenching.Communicated by Ramaswamy H. Sarma.

Cancer cells ferment glucose, even under aerobic conditions, following a phenomenon known as the 'Warburg effect.' Hexokinase 2 (HK2) catalyzes the crucial step of phosphorylation of glucose for subsequent utilization in glycolysis and other pathways. HK2 has been proposed as a potential therapeutic target for anti-cancer therapy because of its enhanced expression in glucose-dependent tumors. Here, we have employed structure-based virtual screening using in-house library to identify potential phytoconstituents which could inhibit the HK2 activity. The initial hits were selected based on their binding affinity towards HK2 using the molecular docking approach. Subsequently, the filters for physicochemical properties, PAINS patterns and PASS evaluation were applied to find potential hits against HK2. Finally, we have identified epigallocatechin gallate (EGCG) and quercitrin, two natural compounds with appreciable binding affinity, efficiency and specificity towards the HK2 binding pocket. Both compounds were found to be binding preferentially to the HK2 active site and showed a decent set of drug-like properties. All-atom molecular dynamics (MD) simulations for 100 ns were carried out to see the conformational dynamics, complexes stability and interaction mechanism of HK2 with EGCG and quercitrin. MD simulation results showed that HK2 forms stable protein-ligand complexes with EGCG and quercitrin with consistency throughout the trajectory. Overall, these findings suggest that EGCG and quercitrin might be further exploited as promising scaffolds in the drug development process against HK2..Communicated by Ramaswamy H. Sarma.

Telomeric repeat binding factor 1 (TRF1) is one of the major components of the shelterin complex. It directly binds to the telomere and controls its function by regulating the telomerase acting on it. Several variations are reported in the TRF1 gene; some are associated with variety of diseases. Here, we have studied the structural and functional significance of these variations in the TRFH domain of TRF1. We have used cutting-edge computational methods such as SIFT, PolyPhen-2, PROVEAN, Mutation Assessor, mCSM, SDM, STRUM, MAESTRO, and DUET to predict the effects of 124 mutations in the TRFH domain of TRF1. Out of 124 mutations, we have identified 12 deleterious mutations with high confidence based on their prediction. To see the impact of the finally selected mutations on the structure and stability of TRF1, all-atom molecular dynamics (MD) simulations on TRF1-Wild type (WT), L79R and P150R mutants for 200 ns were carried out. A significant conformational change in the structure of the P150R mutant was observed. Our integrated computational study provides a comprehensive understanding of structural changes in TRF1 incurred due to the mutations and subsequent function, leading to the progression of many diseases.Communicated by Ramaswamy H. Sarma.

Pyruvate dehydrogenase kinase 3 (PDK3) is a multifunctional enzyme that plays a central role in the cancer metabolic switch by blocking pyruvate catabolism in the TCA cycle. PDK3 plays a significant role in the TCA cycle and cancer cell progression, thus, considered as a novel drug target for developing effective therapeutics against varying types of cancer. Here, we employed a structure-based virtual high-throughput screening of natural compounds from the ZINC database to identify potential inhibitors of PDK3. First, the resulted hits were selected on the basis of their physicochemical and ADMET properties. Further, PAINS filter, binding affinities based on the docking analysis and interaction analysis was carried out to find safe and better hits against PDK3. Finally, we identified four natural compounds bearing admirable affinity towards PDK3. Selected compounds showed appreciable drug-like properties and preferentially interact to the residues of the ATP-binding pocket of PDK3. Binding and structural annotations made in docking analysis were supplemented by all-atom molecular dynamics simulations to evaluate the conformational dynamics, stability and interaction mechanism of PDK3 in complex with one of the identified compounds ZINC08764476. PDK3 and ZINC08764476 forming a stable complex throughout the simulation trajectory. We suggest that compound ZINC08764476 may be exploited as a promising scaffold for the development of potential inhibitors of PDK3 to combat cancer and associated diseases.Communicated by Ramaswamy H. Sarma.

Malaria is a global challenge, and its infection is propagated through Plasmodium falciparum , an obligate human parasite. The genome of P. falciparum encodes many proteases that play significant roles in their survival and pathogenesis thus being considered as attractive drug targets. P. falciparum metacaspase-3 (PfMCA3) is one such protease and a validated drug target to control malarial infection. First, we modeled the three-dimensional structure of PfMCA3 and predicted its ligand-binding pocket. The structural features of PfMCA3 were used for virtual screening followed by docking and molecular dynamics (MD) simulation studies to identify potent inhibitors. We used an in-house library of 513 compounds for screening to identify lead molecule fits well in the active site pocket of PfMCA3. The binding affinity and mechanism were investigated by combined docking and MD simulation studies. Docking studies reveal that the selected compounds are forming enough number of non-covalent interactions to the PfMCA3. In the enzyme inhibition assay, one of the selected compounds, H6 was found with appreciable inhibitory potential. MD simulation studies further support the binding of compound H6 with PfMCA3 and formation of a stable complex throughout the simulation trajectory. Taken together, we proposed that compound H6 is a promising lead scaffold that can be further exploited as a potential inhibitor of PfMCA3 for therapeutic management of malarial infection.Communicated by Ramaswamy H. Sarma.

Protection of telomeres 1 (POT1) is a component of the shelterin complex which is crucial for the regulation of telomere length and maintenance. Many naturally occurring mutations in the POT1 gene have been found to be associated with cardiac angiosarcoma, glioma, familial melanoma, and chronic lymphocytic leukemia. In particular, Y89C is a naturally occurring mutation of POT1, responsible for familial melanoma, and the molecular basis of this mutation is unexplored. In this study, we have extensively analyzed the structure of WT and Y89C mutant of POT1 to see the change in the conformational dynamics, free energy landscape, molecular motions and configurational frustration using molecular dynamics (MD) and other bioinformatics approaches. Y89C mutation shows a significant change in the backbone orientation, compactness, residual fluctuation, solvent accessibility, and hydrogen bonding, suggesting an overall destabilization of the protein structure. Besides, essential dynamics, conformation, magnitude, direction of motion and frustration analysis further suggesting the structural loss in POT1 due to Y89C mutation. Free energy landscape analysis also indicates the presence of a single well-defined free-energy minima in case of WT compared to multiple wells defined free energy minima observed in Y89C, clearly suggesting that this mutation leads to reduce the stability of POT1. This study possibly provides a valuable path to understand the molecular basis of Y89C-mediated development of familial melanoma.Communicated by Ramaswamy H. Sarma.

Glutathione (GU), an endogenous antioxidant tripeptide, is frequently transferred in the human brain through N -methyl-d-aspartate receptor (NMDAR), profusely expressed at the blood-brain barrier (BBB) junction. GU, also modifies the characteristics of tight junction proteins (occludin and claudin) at the site of BBB by depolarizing the enzyme, protein tyrosine phosphatase that manifests its usefulness for passive delivery of nanocarriers to the brain. GU, thus, represents itself as an ideal ligand for the surface decoration of nanocarriers to successfully administer them across the brain via receptor-mediated drug delivery pathway. Hence, we have employed here, in-silico approaches to identify the potential GU-like molecules, as appropriate ligand(s) for surface engineering of nanoconstruct with the purpose of attaining targeted drug delivery to the brain. Structure-based virtual screening methods was used to filter PubChem database for the identification of bioactive compounds with >95% structure similarity with GU. We have further screened the compounds against NMDAR using molecular docking approach. Top hits were selected based on their high binding affinities and selectivity towards NMDAR, and their binding pattern was analysed in detail. Finally, all atom molecular dynamics simulation for 100 ns was carried out on free NMDAR and in-presence of the selected GU-like compound, gamma-l-glutamyl-l-cysteine to evaluate complex stability and structural dynamics. In conclusion, gamma-l-glutamyl-l-cysteine may act as potential binding partner of NMDAR which can further be evaluated in drug delivery system to brain across the BBB.Communicated by Ramaswamy H. Sarma.

Protection of telomere 1 (POT1) is a key component of shelterin complex, essential for maintaining telomere length and its regulation. It consists of N -terminal domain (residues 1-299), which interacts with telomeric ssDNA, and the C-terminal domain (residues 320-634) that binds to the tripeptidyl-peptidase I (TPP1). A large number of naturally occurring mutations in the POT1 gene are associated with glioma, cardiac angiosarcoma and cutaneous familial melanoma (FM). In particular, Q94E mutation disrupts the interaction of POT1 with telomeric DNA which subsequently enhances telomere uncapping and elongation and promotes the development of cutaneous familial melanoma. To understand the underlying mechanism of familial melanoma developed by Q94E-mutation, we have performed extensive structure analysis of WT and mutant protein followed by molecular dynamics simulations. Q94E mutation causes a dramatic change in the structure and stability of POT1 protein. A considerable decrease in the flexibility, fluctuation and solvent accessibility of Q94E was observed in comparison to the WT, indicating overall destabilization of protein. Essential dynamics and Anisotropic Network Mode analysis have quantified a significant change in direction and magnitude of conformational motion in Q94E mutant compared to WT. A significant loss of frustration due to Q94E mutation was also observed. Our findings indicate the loss of protein stability and dynamics of POT1 protein by Q94E mutation may be associated with the familial melanoma. AbbreviationsANManisotropic network modeEDessential dynamicsFMfamilial melanomaMDmolecular dynamicsPOT1protection of telomere 1Rgradius of gyrationRMSDroot-mean-square deviationRMSFroot-mean-square fluctuationsSASAsolvent accessible surface areaSIFTsorting Intolerant from TolerantTPP1tripeptidyl-peptidase IWTwild typeCommunicated by Ramaswamy H. Sarma.

Microtubule affinity-regulating kinase 4 (MARK4) has recently been identified as a potential drug target for several complex diseases including cancer, diabetes and neurodegenerative disorders. Inhibition of MARK4 activity is an appealing therapeutic option to treat such diseases. Here, we have performed structure-based virtual high-throughput screening of 100,000 naturally occurring compounds from ZINC database against MARK4 to find its potential inhibitors. The resulted hits were selected, based on the binding affinities, docking scores and selectivity. Further, binding energy calculation, Lipinski filtration and ADMET prediction were carried out to find safe and better hits against MARK4. Best 10 compounds bearing high specificity and binding efficiency were selected, and their binding pattern to MARK4 was analyzed in detail. Finally, 100 ns molecular dynamics simulation was performed to evaluate; the dynamics stability of MARK4-compound complex. In conclusion, these selected natural compounds from ZINC database might be potential leads against MARK4, and can further be exploited in drug design and development for associated diseases.