A Chemical Inhibitor of Cell Growth Reduces Cell Size in Bacillus subtilis

Abstract

Bacteria exhibit complex responses to biologically active small molecules. These responses include reductions in transcriptional and translational efficiency, alterations in metabolic flux, and in some cases, dramatic changes in growth and morphology. Here, we describe Min-1, a novel small molecule that inhibits growth of Gram-positive bacteria by targeting the cell envelope. Subinhibitory levels of Min-1 inhibits sporulation in Streptomyces venezuelae and reduces growth rate and cell length in Bacillus subtilis. The effect of Min-1 on B. subtilis cell length is significant at high growth rates sustained by nutrient rich media but drops off when growth rate is reduced during growth on less energy rich carbon sources. In each medium, Min-1 has no impact on the proportion of cells containing FtsZ-rings, suggesting that Min-1 reduces the mass at which FtsZ assembly is initiated. The effect of Min-1 on size is independent of UDP-glucose, which couples cell division to carbon availability, and the alarmone ppGpp, which reduces cell size via its impact on fatty acid synthesis. Min-1 activates the LiaRS stress response, which is sensitive to disruptions in the lipid II cycle and the cell membrane, and also compromises cell membrane integrity. Therefore, this novel synthetic molecule inhibits growth at high concentrations and induces a short-cell phenotype at sub-inhibitory concentrations that is independent of known systems that influence cell length, highlighting the complex interactions between small molecules and cell morphology.

Discovery of a Novel DNA Gyrase-Targeting Antibiotic through the Chemical Perturbation of Streptomyces venezuelae Sporulation

“…Intriguingly, some of the compounds that target sporulation turned out to have antibacterial effects against rod-shaped and coccoid bacteria, such as Bacillus subtilis and Staphylococcus aureus. These molecules targeted cells in unusual ways that are clearly outside the most common suite of antibiotic targets: one compound blocked septation (Jani et al., 2015) and another interfered with the relationship between cell growth and cell division (McAuley et al., 2019).…”

The Lasso Peptide Siamycin-I Targets Lipid II at the Gram-Positive Cell Surface

“…Minimum inhibitory concentrations were determined as previously reported. 5 Experiments were performed in triplicate over three biological replicates.…”

“…The cell wall is a key determinant of cell integrity. It modulates osmotic pressure, cell size, and cell shape and protects the cytoplasm from harmful agents. − Moreover, cell wall synthesis requires a tight coordination with cell division. The cell wall is composed of peptidoglycan, a polymer of repeating disaccharide units composed of N-acetyl-glucosamine (GlcNAc) and N-acetyl-muramic acid (MurNAc) cross-linked via short peptides.…”

Length-based separation of Bacillus subtilis bacterial populations by viscoelastic microfluidics

“…They are approximately 2.7 µm long during the stationary phase 43 and significantly longer during the exponential phase, where they can form chains of filaments 44 . In addition to different phases of growth, the morphology and size variations of B. subtilis are also affected by the growth conditions (e.g., nutrient composition 45 and antibiotics 46,47 ) in which B. subtilis is cultured.…”