Mycobacterial FtsZ and inhibitors: a promising target for the anti-tubercular drug development

The novel drug candidate VOMG kills Mycobacterium abscessus and other pathogens by inhibiting cell division

AIMS

The incidence of lung infections is increasing worldwide in individuals suffering from cystic fibrosis and chronic obstructive pulmonary disease. Mycobacterium abscessus is associated with chronic lung deterioration in these populations. The intrinsic resistance of M. abscessus to most conventional antibiotics jeopardizes treatment success rates. To date, no single drug has been developed targeting M. abscessus specifically. The objective of this study was to characterize VOMG, a pyrithione-core drug-like small molecule, as a new compound active against M. abscessus and other pathogens.

METHODS

A multi-disciplinary approach including microbiological, chemical, biochemical and transcriptomics procedures was used to validate VOMG as a promising anti-M. abscessus drug candidate.

RESULTS

To the authors' knowledge, this is the first study to report the in-vitro and in-vivo bactericidal activity of VOMG against M. abscessus and other pathogens. Besides being active against M. abscessus biofilm, the compound showed a favourable pharmacological (ADME-Tox) profile. Frequency of resistance studies were unable to isolate resistant mutants. VOMG inhibits cell division, particularly the FtsZ enzyme.

CONCLUSIONS

VOMG is a new drug-like molecule active against M. abscessus, inhibiting cell division with broad-spectrum activity against other microbial pathogens.

An adamantyl-caffeoyl-anilide exhibits broad-spectrum antibacterial activity by inhibiting FtsZ assembly and Z-ring formation

Several harmful bacteria have evolved resistance to conventional antibiotics due to their extensive usage. FtsZ, a principal bacterial cell division protein, is considered as an important drug target to combat resistance. We identified a caffeoyl anilide derivative, (E)-N-(4-(3-(3,4-dihydroxyphenyl)acryloyl)phenyl)-1-adamantylamide (compound 11) as a new antimicrobial agent targeting FtsZ. Compound 11 caused cell elongation in Mycobacterium smegmatis, Bacillus subtilis, and Escherichia coli cells, indicating that it inhibits cell partitioning. Compound 11 inhibited the assembly of Mycobacterium smegmatis FtsZ (MsFtsZ), forming short and thin filaments in vitro. Interestingly, the compound increased the rate of GTP hydrolysis of MsFtsZ. Compound 11 also impeded the assembly of Mycobacterium tuberculosis FtsZ. Fluorescence and absorption spectroscopic analysis suggested that compound 11 binds to MsFtsZ and produces conformational changes in FtsZ. The docking analysis indicated that the compound binds at the interdomain cleft of MsFtsZ. Further, it caused delocalization of the Z-ring in Mycobacterium smegmatis and Bacillus subtilis without affecting DNA segregation. Notably, compound 11 did not inhibit tubulin polymerization, the eukaryotic homolog of FtsZ, suggesting its specificity on bacteria. The evidence indicated that compound 11 exerts its antibacterial effect by impeding FtsZ assembly and has the potential to be developed as a broad-spectrum antimicrobial agent.