Solution structure of the type I polyketide synthase Pks13 from Mycobacterium tuberculosis

In-situ treatment of gaseous benzene in fixed-bed biofilter with polyurethane foam: Functional population response and benzene transformation pathway

Volatile organic compounds emitted from landfills posed adverse effect on health. In this study, gaseous benzene was biologically treated using an in-situ biofilter without air pump. Its performance was investigated and the removal efficiency of benzene reached over 90 %. The decrease in the average benzene concentration was consistent with first-order reaction kinetics. Mycolicibacterium dominated the bacterial consortium (41-57 %) throughout the degradation. Annotation of genes by metagenomic analysis helped to deduce the degradation pathways (benzene degradation, catechol ortho-cleavage and meta-cleavage) and to reveal the contribution of different species to the degradation process. In total, 21 kinds of key genes and 13 enzymes were involved in the three modules of benzene transformation. Mycolicibacter icosiumassiliensis and Sphingobium sp. SCG-1 carried multiple functional genes critically involved in benzene biodegradation. These findings provide technical and theoretical support for the in-situ bioremediation of benzene-contaminated soil and waste gas reduction in landfills.

In silico drug design strategies for discovering novel tuberculosis therapeutics

INTRODUCTION

Tuberculosis remains a significant concern in global public health due to its intricate biology and propensity for developing antibiotic resistance. Discovering new drugs is a protracted and expensive endeavor, often spanning over a decade and incurring costs in the billions. However, computer-aided drug design (CADD) has surfaced as a nimbler and more cost-effective alternative. CADD tools enable us to decipher the interactions between therapeutic targets and novel drugs, making them invaluable in the quest for new tuberculosis treatments.

AREAS COVERED

In this review, the authors explore recent advancements in tuberculosis drug discovery enabled by in silico tools. The main objectives of this review article are to highlight emerging drug candidates identified through in silico methods and to provide an update on the therapeutic targets associated with Mycobacterium tuberculosis.

EXPERT OPINION

These in silico methods have not only streamlined the drug discovery process but also opened up new horizons for finding novel drug candidates and repositioning existing ones. The continued advancements in these fields hold great promise for more efficient, ethical, and successful drug development in the future.

19 Schiff bases as antimycobacterial agents: synthesis, molecular docking and a plausible mechanism of action

Aim: To discover novel anti-Mycobacterium tuberculosis (Mtb) drugs, 19 compounds were synthesized; their anti-Mtb effects were evaluated and mechanisms of action were preliminarily explored. Materials & methods: The compounds were synthesized and their anti-Mtb activity was elucidated using resazurin microtiter assays. The plausible target of the potential compound was investigated by microimaging techniques, gas chromatography-mass spectrometry analysis and molecular docking. Results: 19 compounds inhibited Mtb growth with minimum inhibitory concentrations ranging from 1 to 32 μg/ml. Compounds 1-17 showed inhibition of Mtb KatG enzyme. Compound 19, the most potent, might be an inhibitor of Pks13 polyketide synthase. Conclusion: This study suggests that 2-((6-fluoropyridin-3-yl)methylene) hydrazine-1-carbothioamide (19) is a potential anti-Mtb lead compound with a novel mechanism of action.

A dissected non-ribosomal peptide synthetase maintains activity

Non-ribosomal peptide synthetases (NRPSs) generate chemically complex compounds and their modular architecture suggests that changing their domain organization can predictably alter their products. Ebony, a small three-domain NRPS, catalyzes the formation of β-alanine containing amides from biogenic amines. To examine the necessity of interdomain interactions, we modeled and docked domains of Ebony to reveal potential interfaces between them. Testing the same domain combinations in vitro showed that 8 % of activity was preserved after Ebony was dissected into a di-domain and a detached C-terminal domain, suggesting that sufficient interaction was maintained after dissection. Our work creates a model to identify domain interfaces necessary for catalysis, an important step toward utilizing Ebony as a combinatorial engineering platform for novel amides.

Structure and dynamics of the essential endogenous mycobacterial polyketide synthase Pks13

The mycolic acid layer of the Mycobacterium tuberculosis cell wall is essential for viability and virulence, and the enzymes responsible for its synthesis are targets for antimycobacterial drug development. Polyketide synthase 13 (Pks13) is a module encoding several enzymatic and transport functions that carries out the condensation of two different long-chain fatty acids to produce mycolic acids. We determined structures by cryogenic-electron microscopy of dimeric multi-enzyme Pks13 purified from mycobacteria under normal growth conditions, captured with native substrates. Structures define the ketosynthase (KS), linker and acyl transferase (AT) domains at 1.8 Å resolution and two alternative locations of the N-terminal acyl carrier protein. These structures suggest intermediate states on the pathway for substrate delivery to the KS domain. Other domains, visible at lower resolution, are flexible relative to the KS-AT core. The chemical structures of three bound endogenous long-chain fatty acid substrates were determined by electrospray ionization mass spectrometry.