Identification of anti-Mycobacterium tuberculosis agents targeting the interaction of bacterial division proteins FtsZ and SepFe

Tuberculosis (TB) is one of the deadly diseases caused by Mycobacterium tuberculosis (Mtb), which presents a significant public health challenge. Treatment of TB relies on the combination of several anti-TB drugs to create shorter and safer regimens. Therefore, new anti-TB agents working by different mechanisms are urgently needed. FtsZ, a tubulin-like protein with GTPase activity, forms a dynamic Z-ring in cell division. Most of FtsZ inhibitors are designed to inhibit GTPase activity. In Mtb, the function of Z-ring is modulated by SepF, a FtsZ binding protein. The FtsZ/SepF interaction is essential for FtsZ bundling and localization at the site of division. Here, we established a yeast two-hybrid based screening system to identify inhibitors of FtsZ/SepF interaction in M. tuberculosis. Using this system, we found compound T0349 showing strong anti-Mtb activity but with low toxicity to other bacteria strains and mice. Moreover, we have demonstrated that T0349 binds specifically to SepF to block FtsZ/SepF interaction by GST pull-down, fluorescence polarization (FP), surface plasmon resonance (SPR) and CRISPRi knockdown assays. Furthermore, T0349 can inhibit bacterial cell division by inducing filamentation and abnormal septum. Our data demonstrated that FtsZ/SepF interaction is a promising anti-TB drug target for identifying agents with novel mechanisms.

Bacterial expression, preparation and identification of polyclonal antibody against Escherichia coli FtsZ / 生物工程学报

To prepare polyclonal antibody (PcAb) against Escherichia coli filamentous thermosensitive protein Z (Ec-FtsZ), the artificially synthesized gene fragment coding Ec-FtsZ was subcloned into pET-22b(+) plasmid, and Ec-FtsZ protein was expressed in E. coli BL21(DE3) cell under an optimal bacterial expression condition. Then Ec-FtsZ protein was purified by HisTrap affinity chromatography, and the GTPase (Guanosine triphosphatase) activity of purified Ec-FtsZ protein was further analyzed by malachite green assay. Subsequently, the purified Ec-FtsZ protein was used to immunize rat subcutaneously for preparation of anti-Ec-FtsZ PcAb. The results of enzyme-linked immunosorbent assay (ELISA), Western blotting analysis and immunofluorescence assay showed that the titer of PcAb was 1:256 000, and PcAb exhibited a perfect antigenic specificity against purified and endogenous Ec-FtsZ protein. All these data indicated that the anti-Ec-FtsZ PcAb is successfully prepared, which can be used for further cellular function study and biochemical analysis of Ec-FtsZ protein in vivo.

Analysis of the key amino acids involved in the function and cellular self-assembly of FtsZ protein in Escherichia coli strains / 中华微生物学和免疫学杂志

Objective To investigate the self-assembly and cellular localization patterns of fila-mentous temperature-sensitive protein Z (FtsZ) in Escherichia coli (E.coli) strains by using FtsZP74R, FtsZG77D and FtsZA81R mutants.Methods YFP or His labeled FtsZ proteins and the plasmids of FtsZ mu-tants were constructed by using molecular clone and site-directed mutagenesis methods.The targeted proteins were purified by affinity chromatography.FL37(△ftsZ-Cat) strains were constructed via linear DNA homol-ogous recombination.Living cell imaging was performed to observe the cellular localization patterns of FtsZ protein and its mutants in E.coli strains.The interactions between FtsZ-FtsZ/FtsZ mutants were examined by coi-mmunoprecipitation assay . The polymerization properties of FtsZ mutants were analyzed by light scattering.The activities of GTPase were monitored by using high performance liquid chromatography.Re-sults The P74, G77 and A81 amino acids were respectively replaced by different polar amino acids to change the amphipathicity of the helix within the domain of FtsZ ( 74-82 ) .The YFP-labeled FtsZP74R , FtsZG77D and FtsZA81R mutants failed to assemble into functional Z-ring structure in E.coli strains.The inter-actions between FtsZ protein and its mutants were weakened or completely disappeared.In addition, in vitro experiments showed that P74R, G77D and A81R mutations caused a decrease in the polymerization efficien-cy of FtsZ monomer.The activity of GTPase was significantly decreased in the FtsZA81R mutant. Conclusion The P74, G77 and A81 were critical amino acids in the function and assembly of FtsZ protein in E.coli strains.Moreover, A81 amino acid regulated the lateral interaction of FtsZ monomer and the activity of GTPase.

Viriditoxin Induces G2/M Cell Cycle Arrest and Apoptosis in A549 Human Lung Cancer Cells

Viriditoxin is a fungal metabolite isolated from Paecilomyces variotii, which was derived from the giant jellyfish Nemopilema nomurai. Viriditoxin was reported to inhibit polymerization of FtsZ, which is a key protein for bacterial cell division and a structural homologue of eukaryotic tubulin. Both tubulin and FtsZ contain a GTP-binding domain, have GTPase activity, assemble into protofilaments, two-dimensional sheets, and protofilament rings, and share substantial structural identities. Accordingly, we hypothesized that viriditoxin may inhibit eukaryotic cell division by inhibiting tubulin polymerization as in the case of bacterial FtsZ inhibition. Docking simulation of viriditoxin to beta-tubulin indicated that it binds to the paclitaxel-binding domain and makes hydrogen bonds with Thr276 and Gly370 in the same manner as paclitaxel. Viriditoxin suppressed growth of A549 human lung cancer cells, and inhibited cell division with G2/M cell cycle arrest, leading to apoptotic cell death.

Variations in the sensitivity of different primers for detecting Wolbachia in Anastrepha (diptera: tephritidae)

Wolbachia are endosymbiont bacteria of the family Rickettsiacea that are widespread in invertebrates and occur between 20 percent and 60 percent of Neotropical insects. These bacteria are responsible for reproductive phenomena such as cytoplasmic incompatibility, male killing, feminization and parthenogenesis. Supergroups A and B of Wolbachia are common in insects and can be identified using primers for 16S rDNA, ftsZ and wsp; these primers vary in their ability to detect Wolbachia. The ftsZ primer was the first primer used to detect Wolbachia in Anastrepha fruit flies. The primers for 16S rDNA, ftsZ and wsp and the corresponding PCR conditions have been optimized to study the distribution of Wolbachia and their effect on the biology of Anastrepha in Brazil. In this work, we examined the ability of these primers to detect Wolbachia in Anastrepha populations from three regions in the State of São Paulo, southeastern Brazil. All of the samples were positive for Wolbachia supergroup A when screened with primers for 16S A rDNA and wsp A; the wsp B primer also gave a positive result, indicating cross-reactivity. The ftsZ primer showed a poor ability to detect Wolbachia in Anastrepha and generated false negatives in 44.9 percent of the samples. These findings indicate that reliable PCR detection of Wolbachia requires the use of primers for 16S rDNA and wsp to avoid cross-reactions and false negatives, and that the ftsZ primer needs to be redesigned to improve its selectivity.