BackgroundPlasmodium parasites are causative agents of malaria which affects >500 million people and claims ~2 million lives annually. The completion of Plasmodium genome sequencing and availability of PlasmoDB database has provided a platform for systematic study of parasite genome. Aminoacyl-tRNA synthetases (aaRSs) are pivotal enzymes for protein translation and other vital cellular processes. We report an extensive analysis of the Plasmodium falciparum genome to identify and classify aaRSs in this organism.ResultsUsing various computational and bioinformatics tools, we have identified 37 aaRSs in P. falciparum. Our key observations are: (i) fraction of proteome dedicated to aaRSs in P. falciparum is very high compared to many other organisms; (ii) 23 out of 37 Pf-aaRS sequences contain signal peptides possibly directing them to different cellular organelles; (iii) expression profiles of Pf-aaRSs vary considerably at various life cycle stages of the parasite; (iv) several PfaaRSs posses very unusual domain architectures; (v) phylogenetic analyses reveal evolutionary relatedness of several parasite aaRSs to bacterial and plants aaRSs; (vi) three dimensional structural modelling has provided insights which could be exploited in inhibitor discovery against parasite aaRSs.ConclusionWe have identified 37 Pf-aaRSs based on our bioinformatics analysis. Our data reveal several unique attributes in this protein family. We have annotated all 37 Pf-aaRSs based on predicted localization, phylogenetics, domain architectures and their overall protein expression profiles. The sets of distinct features elaborated in this work will provide a platform for experimental dissection of this family of enzymes, possibly for the discovery of novel drugs against malaria.

The increasing incidence of human candidiasis and the tendency of Candida species to become resistant to existing chemotherapies are well-recognized health problems. The present study demonstrates the successful synthesis of novel triazole-amino acid hybrids with potent in vitro and in vivo inhibitory activity against Candida species. Particularly, compounds 68 and 70 showed potent in vitro activity against fluconazole (FLC) resistant as well as sensitive clinical isolates of Candida albicans. Time kill curve analysis of lead inhibitors 68 and 70 showed their fungistatic nature. Secretion of hydrolytic enzymes, mainly proteinases and phospholipases, decreased considerably in the presence of 68 and 70 indicating their interference in fungal virulence. TEM analysis of Candida cells exposed to compounds 68 and 70 clearly showed morphological changes and intracellular damage as their possible mode of action. A preliminary mechanistic study carried out on the two most effective inhibitors (68 and 70) revealed the inhibition of ergosterol biosynthesis thereby causing the cells to lose their integrity and viability. The selected compounds did not show significant cytotoxicity up to a concentration of 200 μg mL in the HEK293 cell line. An in silico analysis of 68 and 70 binding to a modeled C. albicans CYP51 showed critical H-bonding as well as hydrophobic interactions with the important active site residues indicating the basis of their anti-Candida role. Studies on the larvae of Galleria mellonella showed that the selected inhibitors (68 and 70) were non-toxic, did not provoke an immune response and significantly reduced Candida proliferation in vivo.

Data-independent acquisition (DIA) mass spectrometry, also known as Sequential Window Acquisition of all Theoretical Mass Spectra (SWATH), is a popular label-free proteomics strategy to comprehensively quantify peptides/proteins utilizing mass spectral libraries to decipher inherently multiplexed spectra collected linearly across a mass range. Although there are many spectral libraries produced worldwide, the quality control of these libraries is lacking. We present the DIALib-QC (DIA library quality control) software tool for the systematic evaluation of a library’s characteristics, completeness and correctness across 62 parameters of compliance, and further provide the option to improve its quality. We demonstrate its utility in assessing and repairing spectral libraries for correctness, accuracy and sensitivity.