Yeast Double Transporter Gene Deletion Library for Identification of Xenobiotic Carriers in Low or High Throughput.

The routes of uptake and efflux should be considered when developing new drugs so that they can effectively address their intracellular targets. As a general rule, drugs appear to enter cells via protein carriers that normally carry nutrients or metabolites. A previously developed pipeline that searched for drug transporters using Saccharomyces cerevisiae mutants carrying single-gene deletions identified import routes for most compounds tested. However, due to the redundancy of transporter functions, we propose that this methodology can be improved by utilizing double mutant strains in both low- and high-throughput screens. We constructed a library of over 14,000 strains harboring double deletions of genes encoding 122 nonessential plasma membrane transporters and performed low- and high-throughput screens identifying possible drug import routes for 23 compounds. In addition, the high-throughput assay enabled the identification of putative efflux routes for 21 compounds. Focusing on azole antifungals, we were able to identify the involvement of the myo-inositol transporter, Itr1p, in the uptake of these molecules and to confirm the role of Pdr5p in their export. IMPORTANCE Our library of double transporter deletion strains is a powerful tool for rapid identification of potential drug import and export routes, which can aid in determining the chemical groups necessary for transport via specific carriers. This information may be translated into a better design of drugs for optimal absorption by target tissues and the development of drugs whose utility is less likely to be compromised by the selection of resistant mutants.Bill & Melinda Gates Foundation FAPES

Using DNA barcodes to identify forensically important species of Diptera in Espírito Santo State, Brazil

ABSTRACT Accurate insect specimen identification is usually a crucial first step in a forensic entomological analysis. It is traditionally done by morphological classification using identification keys. However, due to sensibility limitations in the identification of animal species based only on their morphology, new methods have been developed, including species identification by DNA barcodes. The objective of this study was to identify forensically important species of Diptera in Espirito Santo state using DNA barcodes. For this, adult flies were collected in Espirito Santo, Southeast Region of Brazil. After DNA extraction, COI gene was amplified and sequenced. All sequences were matched to BOLD platform and alternatively to GenBank MegaBLAST. As result, 281 adult flies were collected and identified morphologically. From these, 36% of samples were classified as Calliphoridae, 34% of Muscidae and 30% of Sarcophagidae. Approximately 10% of all collected samples were analyzes by DNA. It was possible to identify only 35.7% of tested samples, probably due to lack of samples deposited in databases. Therefore, more efforts should be made to deposit a greater variety of dipterous in databases to allow the use of this technique in forensic routine, especially in BOLD

Structural features and development of an assay platform of the parasite target deoxyhypusine synthase of Brugia malayi and Leishmania major.

Deoxyhypusine synthase (DHS) catalyzes the first step of the post-translational modification of eukaryotic translation factor 5A (eIF5A), which is the only known protein containing the amino acid hypusine. Both proteins are essential for eukaryotic cell viability, and DHS has been suggested as a good candidate target for small molecule-based therapies against eukaryotic pathogens. In this work, we focused on the DHS enzymes from Brugia malayi and Leishmania major, the causative agents of lymphatic filariasis and cutaneous leishmaniasis, respectively. To enable B. malayi (Bm)DHS for future target-based drug discovery programs, we determined its crystal structure bound to cofactor NAD+. We also reported an in vitro biochemical assay for this enzyme that is amenable to a high-throughput screening format. The L. major genome encodes two DHS paralogs, and attempts to produce them recombinantly in bacterial cells were not successful. Nevertheless, we showed that ectopic expression of both LmDHS paralogs can rescue yeast cells lacking the endogenous DHS-encoding gene (dys1). Thus, functionally complemented dys1Δ yeast mutants can be used to screen for new inhibitors of the L. major enzyme. We used the known human DHS inhibitor GC7 to validate both in vitro and yeast-based DHS assays. Our results show that BmDHS is a homotetrameric enzyme that shares many features with its human homologue, whereas LmDHS paralogs are likely to form a heterotetrameric complex and have a distinct regulatory mechanism. We expect our work to facilitate the identification and development of new DHS inhibitors that can be used to validate these enzymes as vulnerable targets for therapeutic interventions against B. malayi and L. major infections