Engineered CAR-T cells: An immunotherapeutic approach for cancer treatment and beyond.

Chimeric Antigen Receptor (CAR) T cell therapy is a type of adoptive immunotherapy that offers a promising avenue for enhancing cancer treatment since traditional cancer treatments like chemotherapy, surgery, and radiation therapy have proven insufficient in completely eradicating tumors, despite the relatively positive outcomes. It has been observed that CAR-T cell therapy has shown promising results in treating the majority of hematological malignancies but also have a wide scope for other cancer types. CAR is an extra receptor on the T-cell that helps to increase and accelerate tumor destruction by efficiently activating the immune system. It is made up of three domains, the ectodomain, transmembrane, and the endodomain. The ectodomain is essential for antigen recognition and binding, whereas the co-stimulatory signal is transduced by the endodomain. To date, the Food and Drug Administration (FDA) has granted approval for six CAR-T cell therapies. However, despite its remarkable success, CAR-T therapy is associated with numerous adverse events and has certain limitations. This chapter focuses on the structure and function of the CAR domain, various generations of CAR, and the process of CAR-T cell development, adverse effects, and challenges in CAR-T therapy. CAR-T cell therapy also has scopes in other disease conditions which include systemic lupus erythematosus, multiple sclerosis, and myocardial fibrosis, etc.

HIV-1 capsid and viral DNA integration.

IMPORTANCE: HIV-1 capsid protein (CA)-independently or by recruiting host factors-mediates several key steps of virus replication in the cytoplasm and nucleus of the target cell. Research in the recent years have established that CA is multifunctional and genetically fragile of all the HIV-1 proteins. Accordingly, CA has emerged as a validated and high priority therapeutic target, and the first CA-targeting antiviral drug was recently approved for treating multi-drug resistant HIV-1 infection. However, development of next generation CA inhibitors depends on a better understanding of CA's known roles, as well as probing of CA's novel roles, in HIV-1 replication. In this timely review, we present an updated overview of the current state of our understanding of CA's multifunctional role in HIV-1 replication-with a special emphasis on CA's newfound post-nuclear roles, highlight the pressing knowledge gaps, and discuss directions for future research.

Designing a Multi-Epitope Subunit Vaccine against VP1 Major Coat Protein of JC Polyomavirus.

The JC polyomavirus virus (JCPyV) affects more than 80% of the human population in their early life stage. It mainly affects immunocompromised individuals where virus replication in oligodendrocytes and astrocytes may lead to fatal progressive multifocal encephalopathy (PML). Virus protein 1 (VP1) is one of the major structural proteins of the viral capsid, responsible for keeping the virus alive in the gastrointestinal and urinary tracts. VP1 is often targeted for antiviral drug and vaccine development. Similarly, this study implied immune-informatics and molecular modeling methods to design a multi-epitope subunit vaccine targeting JCPyV. The VP1 protein epitopic sequences, which are highly conserved, were used to build the vaccine. This designed vaccine includes two adjuvants, five HTL epitopes, five CTL epitopes, and two BCL epitopes to stimulate cellular, humoral, and innate immune responses against the JCPyV. Furthermore, molecular dynamics simulation (100 ns) studies were used to examine the interaction and stability of the vaccine protein with TLR4. Trajectory analysis showed that the vaccine and TLR4 receptor form a stable complex. Overall, this study may contribute to the path of vaccine development against JCPyV.

Identifying novel risk conferring genes involved in glycosylation processes with familial schizophrenia in an Indian cohort: Prediction of ADAMTS9 gene variant for structural stability.

Schizophrenia is a complex neuropsychiatric disorder and heritability is as high as 80 % making it the most heritable mental disorder. Although GWAS has identified numerous variants, the pathophysiology is still elusive. Here, an attempt was made to identify genetic risk factors in familial cases of schizophrenia that are associated with a common causative pathway. To achieve this objective, exome sequencing was done in 4 familial cases and identified six unique coding variants in five genes. Among these genes, PIGQ gene has two pathogenic variants, one nonsense and in-frame deletion. One missense variant in GALNT16 and one in GALNT5 have variable damaging score, however, the other variants, in ADAMTS9 and in LTBP4 have the highest damaging score. Further analysis showed that the variant of LTBP4 was not present in the functional domain. The other missense variant in the ADAMTS9 gene was found to be significant and was present in the thrombospondin repeat motif, one of the important motifs. Detailed molecular dynamics simulation study on this variant showed a damaging effect on structural stability. Since, all these genes culminated into the glycosylation process, it was evident that an aberrant glycosylation process may be one of the risk factors. Although, extracellular matrix formation through glycosylation have been shown to be associated, the involvement of ADAMTS9 and PIGQ gene mediated glycosylation has not been reported. In this paper, a novel link between ADAMTS9 and PIGQ gene with schizophrenia have been reported. Therefore, this novel observation has contributed immensely to the existing knowledge on risk factor of Schizophrenia.

Resolving colistin resistance and heteroresistance in Enterobacter species.

Species within the Enterobacter cloacae complex (ECC) include globally important nosocomial pathogens. A three-year study of ECC in Germany identified Enterobacter xiangfangensis as the most common species (65.5%) detected, a result replicated by examining a global pool of 3246 isolates. Antibiotic resistance profiling revealed widespread resistance and heteroresistance to the antibiotic colistin and detected the mobile colistin resistance (mcr)-9 gene in 19.2% of all isolates. We show that resistance and heteroresistance properties depend on the chromosomal arnBCADTEF gene cassette whose products catalyze transfer of L-Ara4N to lipid A. Using comparative genomics, mutational analysis, and quantitative lipid A profiling we demonstrate that intrinsic lipid A modification levels are genospecies-dependent and governed by allelic variations in phoPQ and mgrB, that encode a two-component sensor-activator system and specific inhibitor peptide. By generating phoPQ chimeras and combining them with mgrB alleles, we show that interactions at the pH-sensing interface of the sensory histidine kinase phoQ dictate arnBCADTEF expression levels. To minimize therapeutic failures, we developed an assay that accurately detects colistin resistance levels for any ECC isolate.

Investigating the novel acetonitrile derivatives as potential SARS-CoV-2 main protease inhibitor using molecular modeling approach.

The COVID-19 is declared a pandemic by World Health Organization (WHO). It causes respiratory illness which leads to oxygen deficiency; it has affected millions of lives all around the globe. It has also been observed that people with diabetes condition are more likely to have severe symptoms when infected with the SARS-CoV2. So, continued efforts are being taken to design and discover potential anti-covid drugs. Earlier, a study reveals that the acetonitrile (2-phenyl-4H-benzopyrimedo [2,1-b]-thiazol-4-yliden) derivatives have potential anti-diabetic activity. Hence, drugs repurpose approach was used to identify the potential acetonitrile derivative targeting the main protease of SARS-CoV2. Here, ADMET, molecular docking, and molecular dynamics simulation techniques were employed, to identify potential acetonitrile compounds against the main protease. The acetonitrile compounds (A to M) show the drug-likeness properties. Next, the molecular docking and dynamics simulation study reveals that acetonitrile compounds A, F, G, and L show a higher binding affinity and have an effect on the structure and dynamics of the main protease. Furthermore, binding energy calculations reveal that the acetonitrile derivative F has a higher binding affinity with the main protease and derivative L has a lower binding affinity with the main protease. The binding affinity of acetonitrile derivatives decreases in the order of F > A > G > L with the main protease. Thus, our computational modeling study provides valuable structural and energetic information of interaction of potential acetonitrile derivatives with the main protease which could be further used as potential lead molecules against the SARS-CoV2.Communicated by Ramaswamy H. Sarma.

Identification of multi-targeting natural antiviral peptides to impede SARS-CoV-2 infection.

SARS-CoV-2 and its variants cause serious health concerns throughout the world. The alarming increase in the daily number of cases has become a nightmare in many low-income countries; although some vaccines are available, their high cost and low vaccine production make them unreachable to ordinary people in developing countries. Other treatment strategies are required for novel therapeutic options. The peptide-based drug is one of the alternatives with low toxicity, more specificity, and ease of synthesis. Herein, we have applied structure-based virtual screening to identify potential peptides targeting the critical proteins of SARS-CoV-2. Non-toxic natural antiviral peptides were selected from the enormous number of peptides. Comparative modeling was applied to prepare a 3D structure of selected peptides. 3D models of the peptides were docked using the ClusPro docking server to determine their binding affinity and peptide-protein interaction. The high-scoring peptides were docked with other crucial proteins to analyze multiple targeting peptides. The two best peptides were subjected to MD simulations to validate the structure stability and evaluated RMSD, RMSF, Rg, SASA, and H-bonding from the trajectory analysis of 100 ns. The proposed lead peptides can be used as a broad-spectrum drug and potentially develop as a therapeutic to combat SARS-CoV-2, positively impacting the current pandemic. Supplementary Information: The online version contains supplementary material available at 10.1007/s11224-022-02113-9.

Computational study of interactions of anti-cancer drug eribulin with human tubulin isotypes.

Microtubules (MTs) are widely targeted for the treatment of various types of cancer due to their essential role in cell division. MTs are polymers made of αß-tubulin heterodimers. These α- and ß-tubulins have 8 and 10 different isotypes, respectively. It is known that a few tubulin isotypes have anti-cancer drug resistance properties, especially ßIII, which shows poor sensitivity to many potent anti-cancer drugs such as eribulin. However, the molecular-level understanding of drug-resistance due to tubulin isotype variation is poorly understood. This paper presents the study of differential binding affinities of different tubulin isotypes with the potent anti-cancer drug eribulin. Eribulin (MT destabilizer) binds at the inter-dimer interface of MTs near the vinca site and induces a lattice deformation, which results in catastrophic events in MT dynamics. In this study, sequence analysis has been done throughway and the binding sites and based on that 2α-tubulin isotypes (αI and αVIII) and 7ß tubulin isotypes (ßI, ßIIa, ßIII, ßIVa, ßVI, ßVII and ßVIII) were selected. In total, 14 combinations were prepared after building homology models of these selected isotypes. Molecular docking and molecular dynamics simulations were performed to deeply understand the binding mode of eribulin at different MT compositions. RMSD, RMSF, radius of gyration, SASA, ligand-protein interactions, and calculations of binding free energy were performed to investigate the eribulin binding variations to tubulin isotypes and it was found that αIßII showed the maximum binding affinity among all 14 systems to eribulin. The ßIII-tubulin isotype, which shows low sensitivity to eribulin in experimental results, had the least binding affinity in the system αVIIIßIII complex and the average binding affinity in the system αIßIII among all 14 systems. Additionally, we performed steered MD simulations and DynDom analysis of the systems with the lowest binding energy (αIßII) and the highest binding energy (αVIIIßIII) and extracted force, displacement, and H-bonding profiles during the pulling simulations to get a better insight.

Thymol Reduces agr-Mediated Virulence Factor Phenol-Soluble Modulin Production in Staphylococcus aureus.

Staphylococcus aureus is a major human bacterial pathogen that carries a large number of virulence factors. Many virulence factors of S. aureus are regulated by the accessory gene regulator (agr) quorum-sensing system. Phenol-soluble modulins (PSMs) are one of the agr-mediated virulence determinants known to play a significant role in S. aureus pathogenesis. In the present study, the efficacy of thymol to inhibit PSM production including δ-toxin in S. aureus was explored. We employed liquid chromatography-mass spectrometry (LC-MS) to quantify the PSMsα1-PSMα4, PSMß1 and PSMß2, and δ-toxin production from culture supernatants. We found that thymol at 0.5 MIC (128 µg/mL) significantly reduced the PSMα and δ-toxin production in S. aureus WKZ-1, WKZ-2, LAC USA300, and ATCC29213. Downregulation in transcription by quantitative real-time (qRT) PCR analysis of response regulator agrA and receptor histidine kinase agrC upon 0.5 MIC thymol treatment affirmed the results of LC-MS quantification of PSMs. In silico molecular docking analysis demonstrated the binding affinity of thymol with receptors AgrA and AgrC. Transmission electron microscopy images revealed no ultrastructural alterations (cell wall and membrane) in thymol-treated WKZ-1 and WKZ-2 S. aureus strains. Here, we demonstrated that thymol reduces various PSM production in S. aureus clinical isolates and reference strains with mass spectrometry.

Febrifugine dihydrochloride as a new oral chemotherapeutic agent against visceral leishmaniasis infection.

Visceral leishmaniasis (VL) is the deadliest form of leishmaniasis without a safer treatment option. This study implies drug repurposing to find a novel antileishmanial compound, namely febrifugine dihydrochloride (FFG) targeting Leishmania antioxidant system. Starting with virtual screening revealed the high binding affinity and lead likeness of FFG against the trypanothione reductase (TR) enzyme of Leishmania donovani, followed by experimental validation. The promastigotes inhibition assay gave the IC50 concentration of FFG and Miltefosine (positive control) as 7.16 ± 1.39 nM and 11.41 ± 0.29 µM, respectively. Their CC50 was found as 451 ± 12.73 nM and 135.9 ± 5.94 µM, respectively. FFG has been shown to increase the reactive oxygen species (ROS), leading to apoptosis-like cell death among L. donovani promastigotes. Spleen touch biopsy resulted in 62% and 55% decreased parasite load with FFG and miltefosine treatment, respectively. Cytokine profiling has shown an increased proinflammatory cytokine response post-FFG treatment. Moreover, FFG is safe on the liver toxicity parameter in mice post-treatment.

Knockdown of capsid protein encoding novel ATPase domain inhibits genome packaging in potato leafroll virus.

Potato leafroll virus (PLRV) uses powerful molecular machines to package its genome into a viral capsid employing ATP as fuel. Although, recent bioinformatics and structural studies have revealed detailed mechanism of DNA packaging, little is known about the mechanochemistry of genome packaging in small plant viruses such as PLRV. We have identified a novel P-loop-containing ATPase domain with two Walker A-like motifs, two arginine fingers, and two sensor motifs distributed throughout the polypeptide chain of PLRV capsid protein (CP). The composition and arrangement of the ATP binding and hydrolysis domain of PLRV CP is unique and rarely reported. The discovery of the system sheds new light on the mechanism of viral genome packaging, regulation of viral assembly process, and evolution of plant viruses. Here, we used the RNAi approach to suppress CP gene expression, which in turn prevented PLRV genome packaging and assembly in Solanum tuberosum cv. Khufri Ashoka. Potato plants agroinfiltrated with siRNA constructs against the CP with ATPase domain exhibited no rolling symptoms upon PLRV infection, indicating that the silencing of CP gene expression is an efficient method for generating PLRV-resistant potato plants. In addition, molecular docking study reveals that the PLRV CP protein has ATP-binding pocket at the interface of each monomer. This further confirms that knockdown of the CP harboring ATP-binding domain could hamper the process of viral genome packaging and assembly. Moreover, our findings provide a robust approach to generate PLRV-resistant potato plants, which can be further extended to other species. Finally, we propose a new mechanism of genome packaging and assembly in plant viruses.

Robust Antitumor Activity and Low Cytokine Production by Novel Humanized Anti-CD19 CAR T Cells.

Recent studies have described the remarkable clinical outcome of anti-CD19 chimeric antigen receptor (CAR) T cells in treating B-cell malignancies. However, over 50% of patients develop life-threatening toxicities associated with cytokine release syndrome which may limit its utilization in low-resource settings. To mitigate the toxicity, we designed a novel humanized anti-CD19 CAR T cells by humanizing the framework region of single-chain variable fragment (scFv) derived from a murine FMC63 mAb and combining it with CD8α transmembrane domain, 4-1BB costimulatory domain, and CD3ζ signaling domain (h1CAR19-8BBζ). Docking studies followed by molecular dynamics simulation revealed that the humanized anti-CD19 scFv (h1CAR19) establishes higher binding affinity and has a flexible molecular structure with CD19 antigen compared with murine scFv (mCAR19). Ex vivo studies with CAR T cells generated from healthy donors and patients with relapsed/refractory B-cell acute lymphoblastic leukemia (B-ALL) expressing either h1CAR19 or mCAR19 showed comparable antitumor activity and proliferation. More importantly, h1CAR19-8BBζ T cells produced lower levels of cytokines (IFNγ, TNFα) upon antigen encounter and reduced the induction of IL6 cytokine from monocytes than mCAR19-8BBζ T cells. There was a comparable proliferation of h1CAR19-8BBζ T cells and mCAR19-8BBζ T cells upon repeated antigen encounter. Finally, h1CAR19-8BBζ T cells efficiently eliminated NALM6 tumor cells in a preclinical model. In conclusion, the distinct structural modification in CAR design confers the novel humanized anti-CD19 CAR with a favorable balance of efficacy to toxicity providing a rationale to test this construct in a phase I trial.

Immunoinformatics approach for a novel multi-epitope subunit vaccine design against various subtypes of Influenza A virus.

Vaccination is the best strategy for the control and prevention of contagious diseases caused by Influenza A viruses. Extraordinary genetic variability and continual evolvability are responsible for the virus having survival and adaptation to host cell immune response, thus rendering the current influenza vaccines with suboptimal effectiveness.Therefore, in the present study, using a novel immunoinformatics approach, we have designed a universal influenza subunit vaccine based on the highly conserved epitopic sequences of rapidly evolving (HA), a moderately evolving (NP) and slow evolving (M1) proteins of the virus. The vaccine design includes 2 peptide adjuvants, 26 CTL epitopes, 9 HTL epitopes, and 7 linear BCL epitopes to induce innate, cellular, and humoral immune responses against Influenza A viruses. We also analyzed the physicochemical properties of the designed construct to validate its thermodynamic stability, hydrophilicity, PI, antigenicity, and allergenicity. Furthermore, we predicted a highly stable tertiary model of the designed subunit vaccine, wherein additional disulfide bonds were incorporated to enhance its stability. The molecular docking and molecular dynamics simulations of the refined vaccine model with TLR3, TLR7, TLR8, MHC-I and MHC-II showed stable vaccine and receptors complexes, thus confirming the immunogenicity of the designed vaccine. Collectively, these findings suggest that our multi-epitope vaccine construct may confer protection against various strains of influenza A virus subtypes, which could prevent the need for annual reformulation of vaccine and alleviate disease burden.

Exploring the interaction of Peloruside-A with drug resistant αßII and αßIII tubulin isotypes in human ovarian carcinoma using a molecular modeling approach.

Microtubules (MTs) play an essential role in mitosis; hence they are identified as potential targets to design novel anti-mitotic agents. MT's are composed of α/ß-tubulin isotypes that are associated with differential drug-resistant effects against MT-targeting agents. Peloruside-A (PLA) is a potent anti-mitotic agent showing excellent activity against taxol-resistant carcinoma. PLA alters MT dynamics by binding to the 'non-taxoid' site of ß-tubulin. The abundance of ßII and ßIII tubulin isotypes in human ovarian carcinoma affects the efficacy of PLA. Nevertheless, the mechanism of PLA resistance due to ßII and ßIII tubulin isotype is not well understood. Therefore, we investigated the interactions of PLA with αßIIa, αßIIb, and αßIII tubulin isotypes which are predominantly expressed in the human ovarian carcinoma, using a molecular modeling approach. A sequence analysis study shows that the ßIII isotype has seven residue variations at the 'non-taxoid' site compared to the ßIIa and ßIIb isotypes. Molecular docking and molecular dynamics simulation revealed that residue variation at the 'non-taxoid' site of ßIII isotype affect PLA binding. Furthermore, binding energy calculations showed that αßIIa has the highest binding towards PLA, whereas αßIIb and αßIII isotypes shows weaker associations with PLA. Our computational study provides valuable structural and energetic information to increase understanding into the origin of PLA resistance in human ovarian carcinoma and could be helpful to develop potential PLA analogs against specific ß-tubulin isotypes expressed in cancer cells.Communicated by Ramaswamy H. Sarma.

Homozygous p.Val89Leu plays an important pathogenic role in 5α-reductase type 2 deficiency patients with homozygous p.Arg246Gln in SRD5A2.

OBJECTIVE: To evaluate the pathogenic role of a few benign variants and hypomorphic pathogenic variants in SRD5A2. DESIGN AND METHODS: We retrospectively analyzed phenotypes and genotypes in 23 Indian patients with genetically proven steroid 5α-reductase 2 (SRD5A2) deficiency. The interactions of the SRD5A2 enzymes resulting due to the most common benign variant (p.Val89Leu), the most common (hypomorphic) pathogenic variant (p.Arg246Gln) and the double variants (p.Val89Leu and p.Arg246Gln) in SRD5A2 were compared with that of the wild type (WT) enzyme by molecular dynamics (MD) simulation. RESULTS: The majority (n = 19, 82.61%) of patients presented for atypical genitalia and had male gender identity (16/20). Including the two novel ones (p.Leu83Pro, p.Ala28Leufs*103), a total of nine different pathogenic variants were observed. p.Arg246Gln was the most common pathogenic variant (n = 12). Homozygous p.Arg246Gln (n = 9) variant was associated with milder undervirilization (Sinnecker score of ≤3a: 8/9 vs 6/14, P = 0.04) and had concurrent homozygous p.Val89Leu in all patients. Interestingly, asymptomatic fathers of two index patients were homozygous for p.Arg246Gln which questioned the pathogenicity of the variation as a sole factor. Unlike all symptomatic homozygous p.Arg246Gln patients who were also homozygous for p.Val89Leu, asymptomatic homozygous p.Arg246Gln fathers were heterozygous for p.Val89Leu. On MD simulation SRD5A2 p.Val89Leu-Testeosterone (T) and SRD5A2 p.Arg246Gln-T complexes, but not SRD5A2 p.Val89Leu and p.Arg246Gln-T complex, demonstrated close interaction between NADPH and T as that of SRD5A2 WT-T. CONCLUSIONS: p.Arg246Gln may not be pathogenic as a sole variation even in the homozygous state; additional contribution of homozygous p.Val89Leu variant may be essential for the pathogenicity of p.Arg246Gln in SRD5A2.

Delineating the interaction of combretastatin A-4 with αß tubulin isotypes present in drug resistant human lung carcinoma using a molecular modeling approach.

Tubulin isotypes are known to regulate microtubule dynamic instability and contribute to the development of drug resistance in certain types of cancers. Combretastatin-A4 (CA-4) has a potent anti-mitotic, vascular disrupting and anti-angiogenic activity. It binds at the interface of αß tubulin heterodimers and inhibits microtubules assembly. Interestingly, the CA-4 resistant human lung carcinoma shows alteration of ßI and ßIII isotype levels, a higher expression of ßI tubulin isotype and a decreased expression of ßIII tubulin isotypes has been reported in drug resistant cell lines. However, the origin of CA-4 resistance in lung carcinoma is not well understood. Here, we investigate the interaction and binding affinities of αßI, αßIIb, αßIII and αßIVa tubulin isotypes with CA-4, employing molecular modeling approaches. Sequence analysis shows that variations in residue composition at the CA-4 binding pocket of ßI, ßIII and ßIVa tubulin isotypes when compared to template ßIIb isotype. Molecular docking result shows that the CA-4 prefers 'cis' conformation in all αß-tubulin isotypes. Molecular dynamics simulation reveal role of H7 helix, T7 loop and H8 helix of ß-tubulin in lower binding affinity of αßI and αßIII isotypes for CA-4. The order of binding energy for CA-4 is αßIIb > αßIVa > αßI > αßIII. This suggest that drug resistance is induced in human lung carcinoma cells by altering the expression of ß-tubulin isotypes namely ßI and ßIII which show lowest binding affinities. Our present study can help in designing potential CA-4 analogs against drug-resistant cancer cells showing altered expression of tubulin isotypes. Abbreviations:CA-4combretastatin-A4MDmolecular dynamicsRMSDroot mean square deviationDSSPdictionary of secondary structure of proteinsVMDvisual molecular dynamics Communicated by Ramaswamy H. Sarma.

Differential binding affinity of tau repeat region R2 with neuronal-specific ß-tubulin isotypes.

Tau is a microtubule-associated protein whose C-terminal domain consisting of four repeat regions R1, R2, R3 and R4 binds to microtubules to stabilize them. In several neurodegenerative diseases, tau detaches from microtubules to form insoluble aggregates leading to tauopathy. Microtubules are made up of αß tubulin subunits. Seven α-tubulin and nine ß-tubulin isotypes have been reported to be present in humans till date. These tubulin isotypes show residue composition variations mainly at C-terminal region and bind to motor proteins and anti-mitotic drugs differently. These tubulin isotypes show tissue specific expression as their relative proportion varies significantly in different type of cells. It is also known that tau binds differently to different cell lines and can either promote or demote microtubule polymerization. However, the relative binding affinity of tau to the different ß-tubulin isotypes present in different cell lines is completely unknown. Here, we study relative binding affinity of Tau repeat region R2 to neuronal specific tubulin isotypes ßI, ßIIb, and ßIII using molecular modelling approach. The order of binding energy of tau with tubulin is ßIII > ßIIb > ßI. Our strategy can be potentially adapted to understand differential binding affinity of tau towards ß-tubulin isotypes present in other cell lines.

Interaction of microtubule depolymerizing agent indanocine with different human αß tubulin isotypes.

Tubulin isotypes are known to regulate the stability and dynamics of microtubules, and are also involved in the development of resistance against microtubule-targeted cancer drugs. Indanocine, a potent microtubule depolymerizing agent, is highly active against multidrug-resistant (MDR) cancer cells without affecting normal cells. It is known to disrupt microtubule dynamics in cells and induce apoptotic cell death. Indanocine is reported to bind to tubulin at the colchicine site i.e. at the interface of αß tubulin heterodimer. However, it's precise binding mode, involved molecular interactions and the binding affinities with different αß-tubulin isotypes present in MDR cells are not well understood. Here, the binding affinities of human αß-tubulin isotypes with indanocine were examined, employing the molecular modeling approach i.e. docking, molecular dynamics simulation and binding energy calculations. Multiple sequence analysis suggests that the amino acid sequences are different in the indanocine binding pockets of ßI, ßIIa, ßIII and ßVI isotypes. However, such differences are not observed in the amino acid sequences of ßIVa, ßIVb, and ßV tubulin isotypes at indanocine binding pockets. Docking and molecular dynamics simulation results show that indanocine prefers the interface binding pocket of αßIIa, αßIII, αßIVb, αßV, and αßVI tubulin isotypes; whereas it is expelled from the interface binding pocket of αßIVa and αßI-tubulin isotypes. Further, binding free energy calculations show that αßVI has the highest binding affinity and αßI has the lowest binding affinity for indanocine among all ß-tubulin isotypes. The binding free energy decreases in the order of αßVI > αßIVb > αßIIa > αßIII > αßV > αßIVa > αßI. Thus, our study provides a significant understanding of involved molecular interactions of indanocine with tubulin isotypes, which may help to design potent indanocine analogues for specific tubulin isotypes in MDR cells in future.

Febrifugine analogues as Leishmania donovani trypanothione reductase inhibitors: binding energy analysis assisted by molecular docking, ADMET and molecular dynamics simulation.

Visceral leishmaniasis affects people from 70 countries worldwide, mostly from Indian, African and south American continent. The increasing resistance to antimonial, miltefosine and frequent toxicity of amphotericin B drives an urgent need to develop an antileishmanial drug with excellent efficacy and safety profile. In this study we have docked series of febrifugine analogues (n = 8813) against trypanothione reductase in three sequential docking modes. Extra precision docking resulted into 108 ligands showing better docking score as compared to two reference ligand. Furthermore, 108 febrifugine analogues and reference inhibitor clomipramine were subjected to ADMET, QikProp and molecular mechanics, the generalized born model and solvent accessibility study to ensure the toxicity caused by compounds and binding-free energy, respectively. Two best ligands (FFG7 and FFG2) qualifying above screening parameters were further subjected to molecular dynamics simulation. Conducting these studies, here we confirmed that 6-chloro-3-[3-(3-hydroxy-2-piperidyl)-2-oxo-propyl]-7-(4-pyridyl) quinazolin-4-one can be potential drug candidate to fight against Leishmania donovani parasites.

Structure-based virtual screening, molecular docking, ADMET and molecular simulations to develop benzoxaborole analogs as potential inhibitor against Leishmania donovani trypanothione reductase.

Visceral leishmaniasis (VL) is the most fatal form of leishmaniasis and it affects 70 countries worldwide. Increasing drug resistant for antileishmanial drugs such as miltefosine, sodium stibogluconate and pentamidine has been reported in the VL endemic region. Amphotericin B has shown potential antileishmanial activity in different formulations but its cost of treatment and associated nephrotoxicity have limited its use by affected people living in the endemic zone. To control the VL infection in the affected countries, it is necessary to develop new antileishmanial compounds with high efficacy and negligible toxicity. Computer aided programs such as binding free energy estimation; ADMET prediction and molecular dynamics simulation can be used to investigate novel antileishmanial molecules in shorter duration. To develop antileishmanial lead molecule, we performed standard precision (SP) docking for 1160 benzoxaborole analogs along with reference inhibitors against trypanothione reductase of Leishmania parasite. Furthermore, extra precision (XP) docking, ADMET prediction, prime MM-GBSA was conducted over 115 ligands, showing better docking score than reference inhibitors to get potential antileishmanial compounds. Simultaneously, area under the curve (AUC) was estimated using ROC plot to validate the SP and XP docking protocol. Later on, two benzoxaborole analogs with best MM-GBSA ΔG-bind were subjected to molecular simulation and docking confirmation to ensure the ligand interaction with TR. The presented drug discovery based on computational study confirms that BOB27 can be used as a potential drug candidate and warrants further experimental investigation to fight against VL in endemic areas.