Therefore orthology proved to be a significant tool that can

Therefore orthology proved to be a significant tool that can be used to link a known drug target with a potential novel target. Clearly, following chemogenomic approaches to predict a given compounds molecular targets has the potential to reveal alternative ligands for existing targets for M. tuberculosis infection and other diseases. Such approaches can also suggest new targets for new drugs and deconvolute their adverse drug reactions. Nevertheless, the limitations of using such models based on the ChEMBL database include the fact that, in general, the predictions do not distinguish between agonists/activators or antagonists/inhibitors; however, the activities of the compounds have been confirmed through experimental validation. In the absence of such corroboration, activities can be inferred based on the predicted targets and compound structure. Additionally, since both the MCNBC and SEA target prediction models are trained on the ChEMBL database of known target-ligand pairs, all predicted targets are biased towards previously studied and reported proteins. Thus, this method is not able to predict directly new, unprecedented, protein targets in biological pathways that havent been thoroughly studied and added to the ChEMBL database. This limitation is however overcome by the recurrence of already validated targets, but with distinct and novel chemotypes from phenotypic screening studies coupled with the consideration of predicted Mtb protein orthologues and in vitro validation. The over-expression studies confirm DHFR as the target of THT1 and THT2: increased target levels enable the cells to survive in MN-64 higher concentrations of drug. In the folate biosynthetic pathway, DHFR generates tetrahydrofolates from DHF, the derivatives of which are consumed by ThyA with the conversion of dUMP to dTMP and the regeneration of DHF. This cycle ensures the replenishment of the intracellular ROR gama modulator 1 stores of THF derivatives, which are used in other essential single-carbon transfers. Inhibition of DHFR results in a reduced production of THF, which is readily used by a major consumer of reduced folates, ThyA, causing a depletion of the stores of THF. Over-expression of ThyA on the DHFR-targeting compounds THT2 resulted in an increased sensitivity to the compound. The increased cellular levels of ThyA would cause a greater turnover of THF, the replenishment of which would be further limited by the inhibition of native levels of DHFR in the cell by the compound. The mutation in ThyA in the spontaneous resistant mutant locates to the active site. It is probable that the mutation causes a reduction in thymidylate synthase activity. Therefore, more folates are available for essential one-carbon