Unraveling the conformational dynamics of glycerol 3-phosphate dehydrogenase, a nicotinamide adenine dinucleotide-dependent enzyme of Leishmania mexicana.

Allosteric changes modulate the enzymatic activity, leading to activation or inhibition of the molecular target. Understanding the induced fit accommodation mechanism of a ligand in its lowest-free energy state and the subsequent conformational changes induced in the protein are important questions for drug design. In the present study, molecular dynamics (MD) simulations, binding free energy calculations, and principal component analysis (PCA) were applied to analyze the glycerol-3-phosphate dehydrogenase of Leishmania mexicana (LmGPDH) conformational changes induced by its cofactor and substrate binding. GPDH is a nicotinamide adenine dinucleotide (NAD)-dependent enzyme, which has been reported as an interesting target for drug discovery and development against leishmaniasis. Despite its relevance for glycolysis and pentose phosphate pathways, the structural flexibility and conformational motions of LmGPDH in complex with NADH and dihydroxyacetone phosphate (DHAP) remain unexplored. Here, we analyzed the conformational dynamics of the enzyme-NADH complex (cofactor), and the enzyme-NADH-DHAP complex (adduct), mapped the hydrogen-bond interactions for the complexes and pointed some structural determinants of the enzyme that emerge from these contacts to NADH and DHAP. Finally, we proposed a consistent mechanism for the conformational changes on the first step of the reversible redox conversion of dihydroxyacetone phosphate to glycerol 3-phosphate, indicating key residues and interactions that could be further explored in drug discovery.

Targeting Peptidyl-prolyl Cis-trans Isomerase NIMA-interacting 1: A Structure-based Virtual Screening Approach to Find Novel Inhibitors.

BACKGROUND: Peptidyl-prolyl cis-trans isomerase NIMA-interacting 1 (Pin1) is an enzyme that isomerizes phosphorylated serine or threonine motifs adjacent to proline residues. Pin1 has important roles in several cellular signaling pathways, consequently impacting the development of multiple types of cancers. METHODS: Based on the previously reported inhibitory activity of pentacyclic triterpenoids isolated from the gum resin of Boswellia genus against Pin1, we designed a computational experiment using molecular docking, pharmacophore filtering, and structural clustering allied to molecular dynamics (MD) simulations and binding free energy calculations to explore the inhibitory activity of new triterpenoids against Pin1 structure. RESULTS: Here, we report different computational evidence that triterpenoids from neem (Azadirachta indica A. Juss), such as 6-deacetylnimbinene, 6-Oacetylnimbandiol, and nimbolide, replicate the binding mode of the Pin1 substrate peptide, interacting with high affinity with the binding site and thus destabilizing the Pin1 structure. CONCLUSIONS: Our results are supported by experimental data, and provide interesting structural insights into their molecular mechanism of action, indicating that their structural scaffolds could be used as a start point to develop new inhibitors against Pin1.

Structural and functional features of enzymes of Mycobacterium tuberculosis peptidoglycan biosynthesis as targets for drug development.

Tuberculosis (TB) is the second leading cause of human mortality from infectious diseases worldwide. The WHO reported 1.3 million deaths and 8.6 million new cases of TB in 2012. Mycobacterium tuberculosis (M. tuberculosis), the infectious bacteria that causes TB, is encapsulated by a thick and robust cell wall. The innermost segment of the cell wall is comprised of peptidoglycan, a layer that is required for survival and growth of the pathogen. Enzymes that catalyse biosynthesis of the peptidoglycan are essential and are therefore attractive targets for discovery of novel antibiotics as humans lack similar enzymes making it possible to selectively target bacteria only. In this paper, we have reviewed the structures and functions of enzymes GlmS, GlmM, GlmU, MurA, MurB, MurC, MurD, MurE and MurF from M. tuberculosis that are involved in peptidoglycan biosynthesis. In addition, we report homology modelled 3D structures of those key enzymes from M. tuberculosis of which the structures are still unknown. We demonstrated that natural substrates can be successfully docked into the active sites of the GlmS and GlmU respectively. It is therefore expected that the models and the data provided herein will facilitate translational research to develop new drugs to treat TB.