TP53 codon 72 polymorphism and type 2 diabetes: a case–control study in South Indian population

Molecular Biology Reports - TP53 functions primarily as a tumor suppressor, controlling a myriad of signalling pathways that prevent a cell from undergoing malignant transformation. This tumor...     

Phosphatidylthreonine and Lipid-Mediated Control of Parasite Virulence

The major membrane phospholipid classes, described thus far, include phosphatidylcholine (PtdCho), phosphatidylethanolamine (PtdEtn), phosphatidylserine (PtdSer), and phosphatidylinositol (PtdIns). Here, we demonstrate the natural occurrence and genetic origin of an exclusive and rather abundant lipid, phosphatidylthreonine (PtdThr), in a common eukaryotic model parasite, Toxoplasma gondii. The parasite expresses a novel enzyme PtdThr synthase (TgPTS) to produce this lipid in its endoplasmic reticulum. Genetic disruption of TgPTS abrogates de novo synthesis of PtdThr and impairs the lytic cycle and virulence of T. gondii. The observed phenotype is caused by a reduced gliding motility, which blights the parasite egress and ensuing host cell invasion. Notably, the PTS mutant can prevent acute as well as yet-incurable chronic toxoplasmosis in a mouse model, which endorses its potential clinical utility as a metabolically attenuated vaccine. Together, the work also illustrates the functional speciation of two evolutionarily related membrane phospholipids, i.e., PtdThr and PtdSer.     

Design and synthesis of some new quinoline-3-carbohydrazone derivatives as potential antimycobacterial agents

A series of 26 new quinoline derivatives carrying active pharmacophores has been synthesized and evaluated for their in vitro antituberculosis activity against Mycobacterium tuberculosis H37Rv (MTB), Mycobacterium smegmatis (MC²), and Mycobacterium fortuitum following the broth micro dilution assay method. Compounds 13e, 13i, 13k, 14a, 14c, 14i, and 14k exhibited significant minimum inhibition concentrations, when compared with first line drugs isoniazid (INH) and rifampicin (RIF) and could be ideally suited for further modifications to obtain more efficacious compounds in the fight against multi-drug resistant tuberculosis.     

Synthesis and Characterization of Polysialic Acid–Uricase Conjugates for the Treatment of Hyperuricemia

Uricase, an enzyme used for the treatment of hyperuricemia, is conjugated with polysialic acid (PSA) of average molecular weight of 10 kDa by reductive amination in presence of NaCNBH3 in order to improve its pharmacological properties. Polysialylation with 50-,100-,150- and 200-fold molar excess of PSA increased the percentage substitution of the free amino groups on enzyme surface (46, 66, 78 and 80 % respectively). The SDS-PAGE is used to visualize the conjugates with increased molecular weight and it retained almost 65 % of their initial specific activity after conjugation. The stability studies at physiological condition reveals improved stability and activity than the native enzyme. The apparent KM of the enzyme has increased slightly from 4.18 × 10^?5 M to 5.46 × 10^?5 M suggesting that the affinity of the substrate to the enzyme has not been altered to a higher extent. The conjugates, when probed against anti-uricase antibodies generated in rabbit, showed a clean decline in the affinity by 35 % and also have retained double the catalytic activity than that of the native enzyme after exposure to antiserum. The results suggest that uricase-PSA conjugates can be used as an alternative to the conventional synthetic polymer-enzyme conjugates.     

Metabolic Cooperation of Glucose and Glutamine Is Essential for the Lytic Cycle of Obligate Intracellular Parasite Toxoplasma gondii

Toxoplasma gondii is a widespread protozoan parasite infecting nearly all warm-blooded organisms. Asexual reproduction of the parasite within its host cells is achieved by consecutive lytic cycles, which necessitates biogenesis of significant energy and biomass. Here we show that glucose and glutamine are the two major physiologically important nutrients used for the synthesis of macromolecules (ATP, nucleic acid, proteins, and lipids) in T. gondii, and either of them is sufficient to ensure the parasite survival. The parasite can counteract genetic ablation of its glucose transporter by increasing the flux of glutamine-derived carbon through the tricarboxylic acid cycle and by concurrently activating gluconeogenesis, which guarantee a continued biogenesis of ATP and biomass for host-cell invasion and parasite replication, respectively. In accord, a pharmacological inhibition of glutaminolysis or oxidative phosphorylation arrests the lytic cycle of the glycolysis-deficient mutant, which is primarily a consequence of impaired invasion due to depletion of ATP. Unexpectedly, however, intracellular parasites continue to proliferate, albeit slower, notwithstanding a simultaneous deprivation of glucose and glutamine. A growth defect in the glycolysis-impaired mutant is caused by a compromised synthesis of lipids, which cannot be counterbalanced by glutamine but can be restored by acetate. Consistently, supplementation of parasite cultures with exogenous acetate can amend the lytic cycle of the glucose transport mutant. Such plasticity in the parasite''s carbon flux enables a growth-and-survival trade-off in assorted nutrient milieus, which may underlie the promiscuous survival of T. gondii tachyzoites in diverse host cells. Our results also indicate a convergence of parasite metabolism with cancer cells.     

Structure prediction of Bestrophin for the induced - fit docking of anthocyanins

Bestrophin, an integral membrane protein existing in basolateral region of the retina is a propitious target for drug discovery. Mutations in the Bestrophin protein cause Best Vitelliform Macular Dystrophy (BVMD) leading to retinal damages and loss of visual acuity. Owing to the lack of three dimensional structure and related structural homologs in the protein data bank, we modeled the bestrophin protein using Robetta ab initio method. Further, no treatment is available for the disease. In this situation, anthocyanins from natural sources are reported to combat retinal damages. Hence, we identified anthocyanins from Syzygium cumini fruit skin using Electrospray Ionization tandem mass spectrometry. These compounds were docked into the predicted bestrophin model to study the interactions within the active site. The results may provide a valuable insight into the structure of bestrophin and efficacy of anthocyanins in molecular docking studies.

Abbreviations

PTP - Putative transmembrane proteins, VMD - Vitelliform macular dystrophy, BVMD - Best''s vitelliform macular dystrophy, RPE - Retinal pigment epithelium, ESI-MS/MS - Electrospray Ionization Tandem Mass Spectrometry, UNIPROT - Universal Protein Resource, PSIPRED - Protein secondary structure prediction, TMH - Transmembrane Helices, SCFS - Syzygium cumini fruit skin DP - Declustering Potential IFD - Induced Fit Docking.     

Cell surface display of functionally active lipases from Yarrowia lipolytica in Pichia pastoris

The lipase genes of Yarrowia lipolytica, LIPY7 and LIPY8, fused with FLO-flocculation domain sequence from Saccharomyces cerevisiae at their N-termini, were expressed in Pichia pastoris KM71. Following the induction with methanol, the recombinant proteins were displayed on the cell surface of P. pastoris, as confirmed by the confocal laser scanning microscopy. The LipY7p and LipY8p were anchored on P. pastoris via the flocculation functional domain of Flo1p. The surface-displayed lipases were characterized for their application as the whole-cell biocatalyst. These lipases can also be cleaved off from their anchor by enterokinase treatment to yield functionally active proteins in the supernatant offering an alternative purification method for LipY7p and LipY8p.     

Plasmid-encoded enzymatic degradation of dimethoate

Dimethoate-degrading enzymatic activity in Bacillus licheniformis, Pseudomonas aeruginosa, Aeromonas hydrophila, Proteus mirabilis and Bacillus pumilus was found to be 6.4, 1.760, 4.09, 1.196 and 0.505 units/mg protein, respectively. The Escherichia coli C600 transconjugants of the isolated bacterial strains also exhibited dimethoate-degrading enzymatic activities. The cured derivatives did not show any decrease in the amount of dimethoate substrate and did not harbour plasmid as found in the original and transconjugant strains. Thus, the ability of enzymatic degradation of dimethoate was plasmid-mediated in B. licheniformis, Ps. aeruginosa, A. hydrophila, P. mirabilis and B. pumilus.