Identification of Novel Tau-Tubulin Kinase 2 Inhibitors Using Computational Approaches.

Tau tubulin kinase 2 (TTBK2) associated with multiple diseases is one of the kinases which phosphorylates tau and tubulin. Numerous efforts have been made to understand the role of TTBK2 in protein folding mechanisms and misfolding behavior. The misfolded protein intermediates form polymers with unwanted aggregation properties that initiate several diseases, including Alzheimer's. The availability of TTBK2 inhibitors can enhance the understanding of the molecular mechanism of action of the kinase and assist in developing novel therapeutics. In the quest for TTBK2 inhibitors, this study focuses on screening two chemical libraries (ChEMBL and ZINC-FDA). The molecular docking, RO5/absorption, distribution, metabolism, and excretion/toxicity, density functional theory, molecular dynamics (MD) simulations, and molecular mechanics with generalized Born and surface area solvation techniques enabled shortlisting of the four most active compounds, namely, ChEMBL1236395, ChEMBL2104398, ChEMBL3427435, and ZINC000000509440. Moreover, 500 ns MD simulation was performed for each complex, which provided valuable insights into the structural changes in the complexes. The relative fluctuation, solvent accessible surface area, atomic gyration, compactness covariance, and free energy landscapes revealed that the compounds could stabilize the TTBK2 protein. Overall, this study would be valuable for the researchers targeting the development of novel TTBK2 inhibitors.

Insights into the structure and dynamics of SARS-CoV-2 spike glycoprotein double mutant L452R-E484Q.

The Receptor Binding Domain (RBD) of SARS-CoV-2, located on the S1 subunit, plays a vital role in the virus binding and its entry into the host cell through angiotensin-converting enzyme 2 (ACE2) receptor. Therefore, understanding the dynamic effects of mutants on the SARS-CoV-2 RBD is essential for discovering drugs to inhibit the virus binding and disrupt its entry into the host cells. A recent study reported a double mutant of SARS-CoV-2, L452R-E484Q, located in the RBD region. Thus, this study employed various computational algorithms and methods to understand the structural impact of both individual variants L452R, E484Q, and the double mutant L452R-E484Q on the native RBD of spike glycoprotein. The effects of the mutations on native RBD structure were predicted by in silico algorithms, which predicted changes in the protein structure and function upon the mutations. Subsequently, molecular dynamics (MD) simulations were employed to understand the conformational stability and functional changes on the RBD upon the mutations. The comparative results of MD simulation parameters displayed that the double mutant induces significant conformational changes in the spike glycoprotein RBD, which may alter its biological functions. Supplementary Information: The online version contains supplementary material available at 10.1007/s13205-022-03151-0.

Structural stability predictions and molecular dynamics simulations of RBD and HR1 mutations associated with SARS-CoV-2 spike glycoprotein.

The COVID-19 pandemic is caused by human transmission and infection of Severe Acute Respiratory Syndrome Corona Virus-2 (SARS-CoV-2). There is no trusted drug against the virus; hence, efforts are on discovering novel inhibitors for the virus. The entry of a SARS-CoV-2 virus particle into a host cell is initiated by its spike glycoprotein and host Angiotensin-Converting Enzyme 2 (ACE2) receptor interaction. Spike glycoprotein domains, namely, the Receptor Binding Domain (RBD) and Heptad Repeat (HR) domains, are essential for this activity. We have studied the impact of mutations such as A348T, N354D, D364Y, G476S, V483A, S494D in the RBD (319-591), and S939F, S940T, T941A, S943P (912-984) in the HR1 domains of spike glycoprotein. Summarily, we utilized the computational screening algorithms to rank the deleterious, damaging and disease-associated spike glycoprotein mutations. Subsequently, to understand the changes in conformation, flexibility and function of the spike glycoprotein mutants, Molecular Dynamics (MD) simulations were performed. The computational predictions and analysis of the MD trajectories suggest that the RBD and HR1 mutations induce significant phenotypic effects on the pre-binding spike glycoprotein structure, which are presumably consequential to its binding to the receptor and provides lead to design inhibitors against the binding.Communicated by Ramaswamy H. Sarma.

The deleterious impact of a non-synonymous SNP on protein structure and function is apparent in hypertension.

Essential hypertension (EH) is a significant health issue around the globe. The indifferent therapy regimen suggests varied physiological functions due to the lifestyle and genetic presentations of an individual. The endothelial nitric oxide synthase (NOS3) gene is a crucial vascular system marker in EH that contributes significantly to the phenotype. Hence, the present study aimed to employ the candidate gene approach and investigate the association between NOS3 single nucleotide polymorphism (SNP) E298D (G894T/rs1799983) by applying several in silico tools and validation through human samples screening. We corroborated computational findings through a case-control study comprising 294 controls and 299 patients; the 894T allele emerged significantly as the risk allele (odds ratio=2.07; P=6.38E-05). The in silico analyses highlighted the significance of E298D on the native structure and function of NOS3. The dynamics simulation study revealed that the variant type 298D caused structural destabilization of the protein to alter its function. Plasma nitrite levels were reduced in patients (P=0.0002), and the same correlated with the 894T allele. Furthermore, correlations were apparent between clinical, genotype, and routine biochemical parameters. To conclude, the study demonstrated a perceptible association between the SNP E298D and NOS3 protein structure stability that appears to have a bearing on the enzyme's function with a deleterious role in EH.

The structural, functional, and dynamic effect of Tau tubulin kinase1 upon a mutation: A neuro-degenerative hotspot.

Alzheimer's disease (AD) is a progressive disorder that causes brain cells to degenerate and die. AD is one of the common causes of dementia that leads to a decline in thinking, behavioral and social skills that disrupts a person's ability to function independently. Tau-tubulin kinase1 (TTBK1) is a crucial disease regulating AD protein, which is majorly responsible for the phosphorylation and accumulation of tau protein at specific Serine/Threonine residues found in paired helical filaments, suggesting its role in tauopathy. TTBK1 involvement in many diseases and the restricted expression of TTBK1 to the central nervous system (CNS) makes TTBK1 an attractive therapeutic target for tauopathies. The genetic variations in TTBK1 are primarily involved in the TTBK1 pathogenesis. This study highlighted the destabilizing, damaging and deleterious effect of the mutation R142Q on TTBK1 structure through computational predictions and molecular dynamics simulations. The protein deviation, fluctuations, conformational dynamics, solvent accessibility, hydrogen bonding, and the residue-residue mapping confirmed the mutant effect to cause structural aberrations, suggesting overall destabilization due to the protein mutation. The presence of well-defined free energy minima was observed in TTBK1-wild type, as opposed to that in the R142Q mutant, reflecting structural deterioration. The overall findings from the study reveal that the presence of R142Q mutation on TTBK1 is responsible for the structural instability, leading to disruption of its biological functions. The mutation could be used as future diagnostic markers in treating AD.

Atomic Resolution Homology Models and Molecular Dynamics Simulations of Plasmodium falciparum Tubulins.

Microtubules are tubulin polymers present in the eukaryotic cytoskeleton essential for structural stability and cell division that are also roadways for intracellular transport of vesicles and organelles. In the human malaria parasite Plasmodium falciparum, apart from providing structural stability and cell division, microtubules also facilitate important biological activities crucial for parasite survival in hosts, such as egression and motility. Hence, parasite structures and processes involving microtubules are among the most important drug targets for discovering much-needed novel Plasmodium inhibitors. The current study aims to construct reliable and high-quality 3D models of α-, ß-, and γ-tubulins using various modeling techniques. We identified a common binding pocket specific to Plasmodium α-, ß-, and γ-tubulins. Molecular dynamics simulations confirmed the stability of the Plasmodium tubulin 3D structures. The models generated in the present study may be used for protein-protein and protein-drug interaction investigations targeted toward designing malaria parasite tubulin-specific inhibitors.

Unravelling high-affinity binding compounds towards transmembrane protease serine 2 enzyme in treating SARS-CoV-2 infection using molecular modelling and docking studies.

The coronavirus disease-19 (COVID-19) outbreak that is caused by a highly contagious severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) has become a zoonotic pandemic, with approximately 24.5 million positive cases and 8.3 lakhs deaths globally. The lack of effective drugs or vaccine provoked the research for drug candidates that can disrupt the spread and progression of the virus. The identification of drug molecules through experimental studies is time-consuming and expensive, so there is a need for developing alternative strategies like in silico approaches which can yield better outcomes in less time. Herein, we selected transmembrane protease serine 2 (TMPRSS2) enzyme, a potential pharmacological target against SARS-CoV-2, involved in the spread and pathogenesis of the virus. Since 3D structure is not available for this protein, the present study aims at homology modelling and validation of TMPRSS2 using Swiss-model server. Validation of the modelled TMPRSS2 using various online tools confirmed model accuracy, topology and stereochemical plausibility. The catalytic triad consisting of Serine-441, Histidine-296 and Aspartic acid-345 was identified as active binding site of TMPRSS2 using existing ligands. Molecular docking studies of various drugs and phytochemicals against the modelled TMPRSS2 were performed using camostat as a standard drug. The results revealed eight potential drug candidates, namely nafamostat, meloxicam, ganodermanontriol, columbin, myricetin, proanthocyanidin A2, jatrorrhizine and baicalein, which were further studied for ADME/T properties. In conclusion, the study unravelled eight high affinity binding compounds, which may serve as potent antagonists against TMPRSS2 to impact COVID-19 drug therapy.

Nano-ellagic acid: inhibitory actions on aldose reductase and α-glucosidase in secondary complications of diabetes, strengthened by in silico docking studies.

Increased blood sugar levels in prolonged diabetes lead to secondary complications such as retinopathy, neuropathy, and nephropathy, which gradually end in death. Synthesis of nano-phytomedicines from active phytoconstituents for novel emerging applications in the field of pharmaceuticals is of huge interest among researchers. In the present investigation, encapsulated ellagic acid (NEA) was synthesized at four different concentrations (0.2%, 0.3%, 0.4%, 0.5%) using ZnO nanoparticles as encapsulating agent. The surface morphology (fiber-like structures) of the nanoparticles were determined by scanning electron microscopy (SEM) and particle size (161-297 nm) and zeta potential (- 54.9-38.4 mV) were determined by dynamic light scattering technique. Further, the α-glucosidase and aldose reductase enzymes were significantly inhibited by the 0.4% of NEA compared to the other concentrations which strengthened our studies in overcoming the secondary complications of diabetes. The interaction analysis between ellagic acid and insulin receptor found Hit 1 among 10 executed ∆G score and energy of - 5.76, - 4.63 kcal/mol and formed polar bond with Arg 113 with - 1.175 Å distance. The residues Arg115, Lys116, Phe118, Ile115, Arg1131, Arg1155, Ile1157, Lys1165 and Phe1186 were found in ligand-protein interactions. ADME/T analysis of hit 1 was within the acceptable range without any toxic functional groups, providing a framework for developing novel therapeutics.