E. coli aggregation and impaired cell division after terahertz irradiation

In this study we demonstrated that exposure of Escherichia coli (E. coli) to terahertz (THz) radiation resulted in a change in the activities of the tdcABCDEFGR and matA–F genes (signs of cell aggregation), gene yjjQ (signs of suppression of cell motility), dicABCF, FtsZ, and minCDE genes (signs of suppression of cell division), sfmACDHF genes (signs of adhesin synthesis), yjbEFGH and gfcA genes (signs of cell envelope stabilization). Moreover, THz radiation induced E. coli csg operon genes of amyloid biosynthesis. Electron microscopy revealed that the irradiated bacteria underwent increased aggregation; 20% of them formed bundle-like structures consisting of two to four pili clumped together. This could be the result of changes in the adhesive properties of the pili. We also found aberrations in cell wall structure in the middle part of the bacterial cell; these aberrations impaired the cell at the initial stages of division and resulted in accumulation of long rod-like cells. Overall, THz radiation was shown to have adverse effects on bacterial populations resulting in cells with abnormal morphology.

Targeting Bacterial Cell Division: A Binding Site-Centered Approach to the Most Promising Inhibitors of the Essential Protein FtsZ

Binary fission is the most common mode of bacterial cell division and is mediated by a multiprotein complex denominated the divisome. The constriction of the Z-ring splits the mother bacterial cell into two daughter cells of the same size. The Z-ring is formed by the polymerization of FtsZ, a bacterial protein homologue of eukaryotic tubulin, and it represents the first step of bacterial cytokinesis. The high grade of conservation of FtsZ in most prokaryotic organisms and its relevance in orchestrating the whole division system make this protein a fascinating target in antibiotic research. Indeed, FtsZ inhibition results in the complete blockage of the division system and, consequently, in a bacteriostatic or a bactericidal effect. Since many papers and reviews already discussed the physiology of FtsZ and its auxiliary proteins, as well as the molecular mechanisms in which they are involved, here, we focus on the discussion of the most compelling FtsZ inhibitors, classified by their main protein binding sites and following a medicinal chemistry approach.

Pdh is involved in the cell division and Normal septation of Streptococcus suis

Streptococcus suis (S. suis) is an important zoonotic pathogen that causes major economic losses in the pig industry worldwide. The S. suis cell division process is an integral part of its growth and reproduction, which is controlled by a complex regulatory network. Pyruvate dehydrogenase (PDH), which catalyzes the oxidative decarboxylation of pyruvate to form acetyl-CoA, while reducing NAD + to NADH, plays an important role in energy metabolism. Recently, we reported that pdh regulates virulence by reducing stress tolerance and biofilm formation in S. suis serotype 2. In this study, we found that deletion of the pdh gene in S. suis resulted in abnormal cell chains, plump morphology and abnormal localization of the Z rings, indicating that the knockout mutant is impaired in its ability to divide. In addition, the interaction between FtsZ and PDH in vitro was confirmed by ELISA, and qRT-PCR analysis revealed that the deletion of the pdh gene results in differential expression of the division-related genes ftsZ, ftsK, ftsl, zapA, divIC, pbp1a, rodA, mreD, and sepF. These results indicate that pdh is involved in the normal formation of Z rings and cell morphology during S. suis cell division.

The ftsZ gene of the endocellular bacterium 'Candidatus Glomeribacter gigasporarum' is preferentially expressed during the symbiotic phases of its host mycorrhizal fungus

The arbuscular mycorrhizal fungus (AM) Gigaspora margarita consistently hosts bacteria, named 'Candidatus Glomeribacter gigasporarum,' inside its cytoplasm. Endobacteria have a positive impact on fungal fitness during the presymbiotic phase, prior to plant roots colonization. We tested the hypothesis that the endobacterium and its cell divisions depend on fungal metabolism, mirroring also the events of the fungal life cycle which are influenced by plant signals. We first cloned a fragment of ftsZ, a marker gene for bacterial division, and then analyzed its expression along the different stages of fungus development. The bacterial gene transcripts showed the highest values when the fungus was associated to the plant, and peaked in the extraradical mycelium. Strigolactones, which are known to stimulate the AM fungal growth, caused a significant transcript increase in the germinated spores in the absence of the plant. The quantitative real-time reverse-transcription polymerase chain reaction data were strengthened by the quantification of the dividing bacteria, which were increasing in number in germinating spores after the strigolactone treatment. The bioactive molecule alone did not cause any change in the number of bacteria after their isolation from the fungus, thus showing that the strigolactone alone cannot confer free-living capacities to the bacterium.