Sindhuprava Rana

Establishment of correlation between in-silico and in-vitro test analysis against Leishmania HGPRT to inhibitors.

Hypoxanthine Phosphoribosyltransferase (HGPRT; EC 2.4.2.8) is a central enzyme in the purine recycling pathway of all protozoan parasites. Protozoan parasites cannot synthesize purine bases (DNA/RNA) which is essential for survival as lack of de-novo pathway. Thus its good target for drug design and discovery as inhibition leads to cessation of replication. PRTase (transferase enzyme) has common PRTase type I folding pattern domain for its activities. Genomic studies revealed the sequence pattern and identified highly conserved residues that catalyzed the reaction in protozoan parasites. A recombinant protein has 24 kDa molecular mass (rLdHGPRT) was cloned, expressed and purified for testing of guanosine monophosphate (GMP) analogous compounds in-vitro by spectroscopically to the rLdHGPRT, lysates protein and MTT assay on Leishmania donovani. The predicted inhibitors of different libraries were screen into FlexX. The reported inhibitors were tested in-vitro. The 2-deoxyguanosine 5-diphosphate (DGD) (IC50 value 12.5 μM) is two times more effective when compared to guanosine-5-diphosphate sodium (GD). Interestingly, LdHGPRT complex has shown stable after 24 ns in molecular dynamics simulation with interacting amino acids are Glu125, Ile127, Lys87 and Val186. QSAR studies revealed the correlation between predicted and experimental values has shown R2 0.998. Concludes that inversely proportional to their docked score with activities.

Structure prediction of gBP21 protein of L. donovani and its molecular interaction

Visceral leishmaniasis (Kala-azar) is a fatal disease caused by the obligate intracellular parasite Leishmania donovani and the available drugs for the treatment are few, and are frequently associated with side effects and toxicity. RNA editing is one of the essential metabolic processes in the kinetoplastids, where the pre-mRNAs are edited post-transcriptionally by the guide RNAs with the addition or deletion of uridine residues. The aim is to block the gBP21 protein involved in RNA editing process thereby other direct and indirect protein activity is reduced and ultimately the editing process in L. donovani is disturbed and it will inhibit the growth. RNA editing factors are RNA-linked proteins essential for in vivo editing i.e. mitochondrial RNA binding protein1 (MRP 1) originally called as gBP21. The model of L. donovani gBP21 (gBP21Ldv) showed that this protein bears an anti-parallel ß sheet (segregated α and ß regions) with ß-ß-ß-ß-α-ß-ß-ß-ß-α-type topology (“whirly” transcription-factor fold). Each of the four ß strands within a given ß-ß-ß-ß-α repeats and form a curved anti-parallel ß-sheet that packs perpendicularly against the sheet from the other repeat. Among all of the computationally screened compounds by the GLIDE program (Schrödinger) and GOLD program hyperoside1a, posaconazole, quercetin, and pentanediol, 427 exhibited higher binding affinities with the modeled gBP21 protein of L. donovani. Ligandfit program (DSv2.5) revealed that DNA, RNA polymerase inhibitors acyclovir, mitomycin C, and daunorubicin have better binding affinity towards gBP21Ldv. These compounds may be given in combination with miltefosine (first line therapy) against patients with VL and other associated disorders like anemia.

Analysis of sequence, structure of GAPDH of Leishmania donovani and its interactions

Drug resistance acquired by Leishmania donovani (Ldv) is a major problem in the treatment and control of visceral leishmaniasis (VL). Glyceraldehyde-3-phosphate dehydrogenase (GAPDH), a major glycolytic enzyme has been targeted as is found in other protozoan which cause diseases like sleeping sickness. GAPDH gene of Ldv (AG83 strain) was amplified, sequenced, and modeled on the basis of crystal structure of Leishmania mexicana. The model of the Ldv GAPDH exhibited NAD-binding domain with Rossmann folding. Virtual screening of different experimentally proved compounds with the crystal and the modeled structures of GAPDH of Leishmania strains revealed diverse binding affinities of different compounds. Comparison of binding affinities (based on different programs) of compounds revealed that discovery studio v2.5 (Ligandfit) was able to predict the most hit compounds, the best hit compounds against GAPDH of Leishmania strains are hydrazine, vetrazine, and benzyl carbazate. It is predicted that patients suffering from both VL and cardiac disorders (atrial fibrillation) may benefit if they are treated with warfarin in conjunction with first-line antileishmanial therapies such as miltefosine and AmBisome.

In Vitro Evaluation of Antileishmanial Activity of Computationally Screened Compounds against Ascorbate Peroxidase To Combat Amphotericin B Drug Resistance

ABSTRACT In visceral leishmaniasis (VL), the host macrophages generate oxidative stress to destroy the pathogen, while Leishmania combats the harmful effect of radicals by redox homeostasis through its unique trypanothione cascade. Leishmania donovani ascorbate peroxidase (LdAPx) is a redox enzyme that regulates the trypanothione cascade and detoxifies the effect of H2O2. The absence of an LdAPx homologue in humans makes it an excellent drug target. In this study, the homology model of LdAPx was built, including heme, and diverse compounds were prefiltered (PAINS, ADMET, and Lipinskis rule of five) and thereafter screened against the LdAPx model. Compounds having good affinity in terms of the Glide XP (extra precision) score were clustered to select diverse compounds for experimental validation. A total of 26 cluster representatives were procured and tested on promastigote culture, yielding 12 compounds with good antileishmanial activity. Out of them, six compounds were safer on the BALB/c peritoneal macrophages and were also effective against disease-causing intracellular amastigotes. Three out of six compounds inhibited recombinant LdAPx in a noncompetitive manner and also demonstrated partial reversion of the resistance property in an amphotericin B (AmB)-resistant strain, which may be due to an increased level of reactive oxygen species (ROS) and decrease of glutathione (GSH) content. However, inhibition of LdAPx in resistant parasites enhanced annexin V staining and activation of metacaspase-like protease activity, which may help in DNA fragmentation and apoptosis-like cell death. Thus, the present study will help in the search for specific hits and templates of potential therapeutic interest and therefore may facilitate the development of new drugs for combination therapy against VL.

Computational Elucidation of Structural Basis for Ligand Binding with Mycobacterium tuberculosis Glucose-1-Phosphate Thymidylyltransferase (RmlA)

Glucose-1-Phosphate Thymidylyltransferase (RmlA) is one of the enzymes in rhamnose biosynthesis pathway, where rhamnose acts as linker of peptidoglycan and arabinogalacton in the cell wall, therefore RmlA is a potential enzyme for the survival of Mycobacterium tuberculosis (Mtb). To go into the depth of the structure for exploring binding regions, homology model of RmlA was built in Prime, Schrodinger v9.2. The model with lowest Discrete Optimized Potential Energy (DOPE) score of -35524.17 kcal/mol and RMSD of 0.1 Å with the template (1H5R_B) was subjected to Molecular Dynamics Simulation (MDS) for 5 ns to achieve its stable folding state. The tertiary structure of the proposed model is composed of α/β/α sandwich type protein with quasi-Rossmann type folding pattern. The substrate, deoxy Thymidine tri phosphate (dTTP) comprises of triphosphate (R1) and methyl (R2) side chains where, R1 is highly essential for the survival of Mtb. Therefore, nineteen side chain analogues of dTTP were designed by substituting R1 and R2 chain of dTTP using Combi Glide, Schrodinger v9.2 and docked with the target RmlA protein. Out of which two analogues such as, 6-[(2R,3S,5R)-5-[5-(2- aminoethyl)-2,4-dioxo-1,2,3,4-tetrahydropyrimidin-1-yl]-3-hydroxyoxolan-2 yl] hexanoic acid (COMP- 11) and 4-(2-{1-[(1S,3S,4S)-3-(5-carboxypentyl)-4-hydroxy-2-methylidenecyclopentyl]-2,4-dioxo- 1,2,3,4-tetrahydropyrimidin-5-yl}ethyl)morpholin-4-ium (COMP-12) showed the highest GLIDE score (-12.55 Kcal/mol and -11.58 Kcal/mol respectively) than that of substrate (-9.725 Kcal/mol). During simulations, hydrogen bonding profile between the two top hits and protein ranges up to 5 strong polar contacts which were much stronger than that of substrate. Similarly, the computational binding free energy of both the analogues was found to be less than -70 Kcal/mol which is much lower than that of substrate (-52.84 Kcal/mol). All these results suggest that these two compounds have more stable interaction than that of substrate inside the solvent condition and can be used as competitive inhibitors.

Computational Identification of microRNA-like Elements in Leishmania major

Leishmaniasis represents endemic infections that occur predominantly, in tropical and sub-tropical regions. The current situation for the chemotherapy of leishmaniasis is more promising than it has been for several decades with both new drugs and new formulations of old drugs either recently approved or in clinical trials. Investigations focused on parasite biology and identification of novel drug targets have become of great importance. The identification and characterization of microRNA (miRNAs) in the parasite and their possible biological action hopefully facilitate the discovery of potential antiparasitic drug targets against leishmaniasis. microRNA and other small RNA transcripts are derived from distinct loci in the genome and play critical roles in RNA-mediated gene silencing mechanisms in the organisms. miRNAs regulate mRNA stability through perfect and imperfect match to the targets. The biological activities of miRNAs have been related to many biological events, from resistant to microbe infections to cellular differentiation. miRNA like-elements have been identified in Leishmania major. Identification of miRNA-like elements in L. major provides a foundation for subsequent functional studies. Computational strategies provide an efficient manner to predict miRNA genes and their targets. Twenty-five potential miRNA-like elements in different chromosomes (chr.) like chr. 7(th), 8(th), 17(th), 18(th), 21(st), 23(rd), 25(th), 26(th), 29(th), 31(st), 32(nd), 33(rd), 34(th) and 35(th) of L. major have been identified. It is known from this study that the target genes of miRNA-like elements involve multidrug resistant protein such as ABC transporter, ribosomal protein, RNA binding proteins, hydrolase and exonuclease.

Structure, evolution and virtual screening of NDM-1 strain from Kolkata

β-lactam antibiotics are utilised to treat bacterial infection. β-lactamase enzymes (EC 3.5.2.6) are produced by several bacteria and are responsible for their resistance to β-lactam antibiotics like penicillin, cephamycins and carbapenems. New Delhi Metallo-β-lactamase (NDM-1) is a gene that makes bacteria resistant to β-lactam antibiotics. Preparing a compound against NDM-1 will require additional investment and development by drug manufacturers as the current antibiotics will not treat patients with NDM-1 resistance. NDM-1 of Kolkata showed convergent-type evolution with other NDM-1 producing strains. The modelled structure exhibited α-β-α barrel-type domain along with Zn metallo-β-lactamase N-terminal domain. Compounds belonging to cephalosporins (relatively resistant to β-lactamase) and other antibiotics ceftaroline, ceftobiprole, piperacillin, penamecillin, azidocillin, cefonicid, tigecycline and colistin have exhibited better binding affinity with the modelled NDM-1.

CPDB: cysteine protease annotation database in Leishmania species

UNLABELLEDnThere has been a revival of interest in Cysteine protease for Visceral Leishmaniasis (VL) attributed to massive outbreaks of leishmaniasis in the tropical region. The cysteine protease database (CPDB) was designed to find data related to cysteine protease (CP) of different species of Leishmania and Trypanosoma brucei in a single platform. This has reflected in substantial increase in the submission of Leishmania genome sequences to NCBI (National Center for Biotechnology Information) database. The CPDB database aims to provide a summary of data analysis, such as physiochemical and molecular properties, proteolytic cleavage sites, classification into functional families using SVMProt and other ExPASy tools. The main aim of this database is to provide different protein inhibitors of cysteine protease groups that were collected from literature and make available their 3-D structures through JMol with JAVA platform. These CP inhibitors are freely downloadable and also have added links for functional analyses of other proteins, which is helpful for users. All this information in CPDB, a single platform, will prove to be of great help for researchers who are involved in drug discovery and analysis of other physiochemical and molecular properties of the protein.nnnAVAILABILITYnthe database is available for free at.