Biology subjects

Cavalier, J.-F.

Publications and source records attributed to Cavalier, J.-F..

3 recordsLinked to original sources

bioRxiv2025

Pyrazinamide kills Mycobacterium tuberculosis via pH-driven weak-acid permeation and cytosolic acidification

Pyrazinamide (PZA) is a cornerstone drug in tuberculosis (TB) treatment with a strong bactericidal activity in vivo on both actively and non-replicating bacterial subpopulations. Yet the precise mode of action of its active form, pyrazinoic acid (POA), remains unclear. In this study, we comprehensively explore and challenge the two major and conflicted models of PZA mode of action. The pH-dependent model, where the drug is mostly effective at acidic pH by acidifying Mycobacterium tuberculosis (Mtb) cytosol, and the PanD-dependent model where PZA active form targets the aspartate decarboxylase PanD, therefore depleting pantothenate (Panto) and subsequently coenzyme A (CoA) levels regardless of the surrounding pH. By combining standard antimicrobial susceptibility testing at various pH with fluorescence-based live recording of Mtb intrabacterial pH (IBpH), we demonstrate that PZA kills Mtb by decreasing IBpH, independently of Panto levels. Comparative studies between a prototrophic Mtb strain and a Panto auxotrophic mutant lacking the panCD locus confirmed that PZA bactericidal activity is primarily driven by pH and its ability to acidify Mtb cytosol, independently of the aspartate decarboxylase PanD. Bio-electrophysiology experiments revealed that acidic pH promotes the conversion of the pyrazinoate anion POA- into HPOA which in turn acts as conventional weak acid that facilitates membrane permeation and cytosolic acidification. Finally, using custom culture media, we demonstrate that PZA displays heterogeneous efficacy according to the media composition, therefore proposing a revisited biological model that might explain the discrepancies around PZA unique mode of action. Overall, this work constitutes the first comprehensive side-by-side investigation of the two models and univocally supports a pH-dependent mechanism of action underlying PZA sterilizing activity, providing new insights for the development of more effective PZA-like drugs.

microbiology↗

bioRxiv2024

Anti-tubercular potential and pH-driven mode of action of salicylic acid derivatives

In the search for new anti-tuberculosis drugs with novel mechanisms of action, we evaluated the antimycobacterial activity of a panel of eight phenolic acids against four pathogenic mycobacterial model species, including M. tuberculosis. We demonstrated that salicylic acid (SA), as well as the iodinated derivatives 5-iodo-salicylic acid (5ISA) and 3,5-diiodo-salicylic acid (3,5diISA), displayed promising antitubercular activities. Remarkably, using a genetically encoded mycobacterial intrabacterial pH reporter, we describe for the first time that SA, 5ISA, 3,5diISA and the anti-inflammatory drug aspirin (ASP) act by disrupting the intrabacterial pH homeostasis of M. tuberculosis in a dose-dependent manner under in vitro conditions mimicking the endolysosomal pH of macrophages. In contrast, the structurally related second-line anti-TB drug 4-aminosalicylic acid (PAS) had no pH-dependent activity and was strongly antagonized by L-methionine supplementation, thereby suggesting distinct modes of action. Finally, we propose that SA, ASP and its two iodinated derivatives could restrict M. tuberculosis growth in a pH-dependent manner by acidifying the cytosol of the bacilli; therefore, making such compounds very attractive for further development.

microbiology↗

bioRxiv2021

A competitive activity-based protein profiling platform yields cell wall synthesis inhibitors active against replicating and non-replicating Mycobacterium tuberculosis

The identification and validation of a small molecules targets is a major bottleneck in the discovery process for tuberculosis antibiotics. Activity-based protein profiling (ABPP) is an efficient tool for determining a small molecules targets within complex proteomes. However, how target inhibition relates to biological activity is often left unexplored. Here we studied the effects of 1,2,3-triazole ureas on Mycobacterium tuberculosis (Mtb). After screening ~200 compounds, we focused on two inhibitors active against both exponentially replicating and hypoxia-induced drug-tolerant Mtb that form part of a four-compound structure-activity series. The compound with negligible activity revealed potential false positive targets not addressed in other ABPP studies. Biochemistry, computational docking, and morphological analysis confirmed that active compounds preferentially inhibit serine hydrolases with cell wall and lipid metabolism functions and that disruption of the cell wall underlies biological activity. Our findings showed that ABPP identifies the targets most likely relevant to a compounds antibacterial activity.

microbiology↗