Vitamin K3 inhibits FtsZ assembly, disrupts the Z-ring in Streptococcus pneumoniae, and displays anti-pneumococcal activity

Identification of ethyl-6-bromo-2((phenylthio)methyl)imidazo[1,2-a]pyridine-3-carboxylate as a narrow spectrum inhibitor of Streptococcus pneumoniae and its FtsZ

Filamentous temperature-sensitive mutant Z (FtsZ) is a key cell-division protein recognized as an important target for anti-bacterial drug discovery, especially in the context of rising multi-drug resistance. A respiratory pathogen, Streptococcus pneumoniae, is rapidly evolving antibiotic resistance, thus posing a clinical risk in the developing world. Inhibiting the conserved protein FtsZ, leading to the arrest of cell division, is an attractive alternative strategy for inhibiting S. pneumoniae. Previously, Vitamin K3 was identified as an FtsZ-targeting agent against S. pneumoniae. In the present work, docking studies were used to identify potential anti-FtsZ agents that bind to the Vitamin K3-binding region of a homology model generated for S. pneumoniae FtsZ. Compounds with imidazo[1,2-a]pyridine-3-carboxylate core were synthesized and screened for their anti-proliferative activity against S. pneumoniae. Remarkably, the hit compound IP-01 showed anti-bacterial action against S. pneumoniae without any activity on other bacteria. In S. pneumoniae, IP-01 showed similar inhibitory action on FtsZ and cell division as Vitamin K3. Sequence alignment identified three unique residues within S. pneumoniae FtsZ that IP-01 binds to, providing a structural basis for the observed specificity. IP-01 is one of the first narrow-spectrum agents identified against S. pneumoniae that targets FtsZ, and we present it as a promising lead for the design of narrow-spectrum anti-FtsZ anti-pneumococcal compounds.

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.

Models versus pathogens: how conserved is the FtsZ in bacteria?

Combating anti-microbial resistance by developing alternative strategies is the need of the hour. Cell division, particularly FtsZ, is being extensively studied for its potential as an alternative target for anti-bacterial therapy. Bacillus subtilis and Escherichia coli are the two well-studied models for research on FtsZ, the leader protein of the cell division machinery. As representatives of gram-positive and gram-negative bacteria, respectively, these organisms have provided an extensive outlook into the process of cell division in rod-shaped bacteria. However, research on other shapes of bacteria, like cocci and ovococci, lags behind that of model rods. Even though most regions of FtsZ show sequence and structural conservation throughout bacteria, the differences in FtsZ functioning and interacting partners establish several different modes of division in different bacteria. In this review, we compare the features of FtsZ and cell division in the model rods B. subtilis and E. coli and the four pathogens: Staphylococcus aureus, Streptococcus pneumoniae, Mycobacterium tuberculosis, and Pseudomonas aeruginosa. Reviewing several recent articles on these pathogenic bacteria, we have highlighted the functioning of FtsZ, the unique roles of FtsZ-associated proteins, and the cell division processes in them. Further, we provide a detailed look at the anti-FtsZ compounds discovered and their target bacteria, emphasizing the need for elucidation of the anti-FtsZ mechanism of action in different bacteria. Current challenges and opportunities in the ongoing journey of identifying potent anti-FtsZ drugs have also been described.