Targeting Mycobacterium tuberculosis: Synthesis, in vitro and in silico evaluation of novel N1 -(benzo[d]oxazol-2-yl)-N4 -arylidine compounds.

The development of novel antimycobacterial agents is an urgent challenge to eradicate the increasing emergence and rapid spread of multidrug-resistant strains. Filamentous temperature-sensitive protein Z (FtsZ) is a crucial cell division protein. Alteration of FtsZ assembly leads to cell division inhibition and cell death. To find novel antimycobacterial agents, a series of N1 -(benzo[d]oxazol-2-yl)-N4 -arylidine compounds 5a-o were synthesized. The activity of the compounds was evaluated against drug-sensitive, multidrug-resistant, and extensive-drug-resistant Mycobacterium tuberculosis. Compounds 5b, 5c, 5l, 5m, and 5o showed promising antimycobacterial activity with minimum inhibitory concentrations (MIC) in the range of 0.48-1.85 µg/mL and with low cytotoxicity against human nontumorigenic lung fibroblast WI-38 cells. The activity of the compounds 5b, 5c, 5l, 5m, and 5o was evaluated against bronchitis causing-bacteria. They exhibited good activity against Streptococcus pneumoniae, Klebsiella pneumoniae, Mycoplasma pneumonia, and Bordetella pertussis. Molecular dynamics simulations of Mtb FtsZ protein-ligand complexes identified the interdomain site as the binding site and key interactions. ADME prediction indicated that the synthesized compounds have drug-likeness. The density function theory studies of 5c, 5l, and 5n were performed to investigate E/Z isomerization. Compounds 5c and 5l are present as E-isomers and 5n as an E/Z mixture. Our experimental outcomes provide an auspicious lead for the design of more selective and potent antimycobacterial drugs.

Intracellular crowding effects on the self-association of the bacterial cell division protein FtsZ.

The dimerization rate of the bacterial cell division protein FtsZ is strongly affected by the intracellular crowding. Yet the complexity of the intracellular environment makes it difficult to investigate via all-atom molecular dynamics or other detailed theoretical methods. We study the crowding effect on FtsZ dimerization which is the first step of an oligomerization process that results in more elaborate supramolecular structures. In particular, we consider the effect of intracellular crowding on the reaction rates, and their dependence on the different concentrations of crowding agents. We achieved this goal by using Brownian dynamics (BD) simulation techniques and a modified post-processing approach in which we decompose the rate constant in crowded media as a product of the rate constant in the dilute solution times a factor that incorporates the crowding effect. The latter factor accounts for the diffusion reduction and crowder induced energy. In addition we include the crowding effects on water viscosity in the BD simulations of crowded media. We finally show that biomolecular crowding has a considerable effect on the FtsZ dimerization by increasing the dimerization rate constant from 2.6×10(7)M(-1)s(-1) in the absence of crowders to 1.0×10(8)M(-1)s(-1) at crowding level of 0.30.

Antimicrobial phytoconstituents from Azadirachta indica (neem) with potential inhibitor against FtsZ protein of Pseudomonas aeruginosa.

Pseudomonas aeruginosa is a well-known pathogen for its rapid development of multi-drug antibiotic resistance. This pathogen is responsible for numerous human diseases, particularly affecting immunocompromised and elderly patients. Hence, discovering novel therapeutics has become necessary in the fight against antimicrobial resistance. This study is focused on evaluating the potential inhibitory activity of eleven phytocompounds from Azadirachta indica against the nucleotide-binding site of the FtsZ protein of P. aeruginosa through a cheminformatics approach. FtsZ is an indispensable and highly conserved protein in prokaryotic cell division. Docking studies revealed favourable binding energies (ΔG= - 8.3 to - 5.4 kcal/mol) for all selected phytoconstituents. Finally, we selected Nimbiol (CID 11119228), as a lead compound, exhibiting a binding energy (ΔG= -7.8 kcal/mol) for the target. Based on our findings, Nimbiol shows potential as an anti-FtsZ compound, making it a promising candidate for further in vitro and in vivo investigations to assess its antimicrobial activity.

Synthesis and Antimycobacterial Activity of 2,5-Disubstituted and 1,2,5-Trisubstituted Benzimidazoles.

The appearance of drug-resistant strains of Mycobacterium tuberculosis and the dramatic increase in infection rates worldwide evidences the urgency of developing new and effective compounds for treating tuberculosis. Benzimidazoles represent one possible source of new compounds given that antimycobacterial activity has already been documented for some derivatives, such as those bearing electron-withdrawing groups. The aim of this study was to synthesize two series of benzimidazoles, di- and trisubstituted derivatives, and evaluate their antimycobacterial activity. Accordingly, 5a and 5b were synthesized from hydroxymoyl halides 3a and 3b, and nitro-substituted o-phenylenediamine 4. Compound 11 was synthesized from an aromatic nitro compound, 4-chloro-1,2-phenylenediamine 9, mixed with 3-nitrobenzaldehyde 10, and bentonite clay. Although the synthesis of 11 has already been reported, its antimycobacterial activity is herein examined for the first time. 1,2,5-trisubstituted benzimidazoles 7a, 7b, and 12 were obtained from N-alkylation of 5a, 5b, and 11. All benzimidazole derivatives were characterized by FT-IR, NMR, and HR-MS, and then screened for their in vitro antimycobacterial effect against the M. tuberculosis H37Rv strain. The N-alkylated molecules (7a, 7b, and 12) generated very limited in vitro inhibition of mycobacterial growth. The benzimidazoles (5a, 5b, and 11) showed in vitro potency against mycobacteria, reflected in minimal inhibitory concentration (MIC) values in the range of 6.25-25 µg/mL. Consequently, only the 2,5-disubstituted benzimidazoles were assessed for biological activity on mouse macrophages infected with M. tuberculosis. A good effect was found for the three compounds. The cytotoxicity assay revealed very low toxicity for all the test compounds against the macrophage cell line. According to the docking study, 2,5-disubstituted benzimidazoles exhibit high affinity for an interdomain cleft that plays a key role in the GTP-dependent polymerization of the filamentous temperature-sensitive Z (FtsZ) protein. The ability of different benzimidazoles to impede FtsZ polymerization is reportedly related to their antimycobacterial activity. On the other hand, the 1,2,5-trisubstituted benzimidazoles docked to the N-terminal of the protein, close to the GTP binding domain, and did not show strong binding energies. Overall, 5a, 5b, and 11 proved to be good candidates for in vivo testing to determine their potential for treating tuberculosis.

Synthesis and Evaluation of the Antibacterial Activities of 13-Substituted Berberine Derivatives.

The biological activities of berberine, a natural plant molecule, are known to be affected by structural modifications, mostly at position 9 and/or 13. A series of new 13-substituted berberine derivatives were synthesized and evaluated in term of antimicrobial activity using various microorganisms associated to human diseases. Contrarily to the original molecule berberine, several derivatives were found strongly active in microbial sensitivity tests against Mycobacterium, Candida albicans and Gram-positive bacteria, including naïve or resistant Bacillus cereus, Staphylococcus aureus and Streptococcus pyogenes with minimal inhibitory concentration (MIC) of 3.12 to 6.25 µM. Among the various Gram-negative strains tested, berberine's derivatives were only found active on Helicobacter pylori and Vibrio alginolyticus (MIC values of 1.5-3.12 µM). Cytotoxicity assays performed on human cells showed that the antimicrobial berberine derivatives caused low toxicity resulting in good therapeutic index values. In addition, a mechanistic approach demonstrated that, contrarily to already known berberine derivatives causing either membrane permeabilization, DNA fragmentation or interacting with FtsZ protein, active derivatives described in this study act through inhibition of the synthesis of peptidoglycan or RNA. Overall, this study shows that these new berberine derivatives can be considered as potent and safe anti-bacterial agents active on human pathogenic microorganisms, including ones resistant to conventional antibiotics.

Enhancing single-cell hyaluronic acid biosynthesis by microbial morphology engineering.

Microbial morphology engineering is a novel approach for cell factory to improve the titer of target product in bio-manufacture. Hyaluronic acid (HA), a valuable glycosaminoglycan polymerized by HA synthase (HAS), a membrane protein, is particularly selected as the model product to improve its single-cell HA-producing capacity via morphology engineering. DivIVA and FtsZ, the cell-elongation and cell division related protein, respectively, were both down/up dual regulated in C. glutamicum via weak promoter substitution or plasmid overexpression. Different from the natural short-rod shape, varied morphologies of engineered cells, i.e. small-ellipsoid-like (DivIVA-reduced), bulb-like (DivIVA-enhanced), long-rod (FtsZ-reduced) and dumbbell-like (FtsZ-enhanced), were observed. Applying these morphology-changed cells as hosts for HA production, the reduced expression of both DivIVA and FtsZ seriously inhibited normal cell growth; meanwhile, overexpression of DivIVA didn't show morphology changes, but overexpression of FtsZ surprisingly change the cell-shape into long and thick rod with remarkably enlarged single-cell surface area (more than 5.2-fold-increase). And finally, the single-cell HA-producing capacity of the FtsZ-overexpressed C. glutamicum was immensely improved by 13.5-folds. Flow cytometry analyses verified that the single-cell HAS amount on membrane was enhanced by 2.1 folds. This work is pretty valuable for high titer synthesis of diverse metabolic products with microbial cell factory.

[Bacterial expression, preparation and identification of polyclonal antibody against Escherichia coli FtsZ].

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.

A combined CoMFA and CoMSIA 3D-QSAR study of benzamide type antibacterial inhibitors of the FtsZ protein in drug-resistant Staphylococcus aureus.

A major problem today is bacterial resistance to antibiotics and the small number of new therapeutic agents approved in recent years. The development of new antibiotics capable of acting on new targets is urgently required. The filamenting temperature-sensitive Z (FtsZ) bacterial protein is a key biomolecule for bacterial division and survival. This makes FtsZ an attractive new pharmacological target for the development of antibacterial agents. There have been several attempts to develop ligands able to inhibit FtsZ. Despite the large number of synthesized compounds that inhibit the FtsZ protein, there are no quantitative structure-activity relationships (QSAR) that allow for the rational design and synthesis of promising new molecules. We present the first 3D-QSAR study of a large and diverse set of molecules that are able to inhibit the FtsZ bacterial protein. We summarize a set of chemical changes that can be made in the steric, electrostatic, hydrophobic and donor/acceptor hydrogen-bonding properties of the pharmacophore, to generate new bioactive molecules against FtsZ. These results provide a rational guide for the design and synthesis of promising new antibacterial agents, supported by the strong statistical parameters obtained from CoMFA (r(2)(pred) = 0.974) and CoMSIA (r(2)(pred) = 0.980) analyses.

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.

Biochemical characterization of two trimers of the bacterial cell division protein (FtsZ) from E. coli / CARACTERIZACIÓN BIOQUÍMICA DE DOS TRÍMEROS DE LA PROTEÍNA DE LA DIVISIÓN CELULAR BACTERIANA (FtsZ) DE E. coli.

FtsZ is a bacterial divisome protein responsible for Z-ring formation in cytokinesis. Characterization of Escherichia coli FtsZ protein oligomers (EcFtsZ) in native conditions is defiance because the protein is found as a multi-oligomer in self-association-dissociation equilibrium. We characterize the trimeric state of EcFtsZ through native PAGE, gel filtration chromatography and sucrose gradient techniques combined with chemical cross-linking. The filtration results indicate that the EcFtsZ trimer has a molecular mass of 131 kDa and a filtration friction coefficient (Rs/Rmin) equal to 1.9, while the theoretical filtration friction coefficient (fn/f1) calculated for a linear trimer yielded a value equal to 1.8 very close to the experimental value. On the other side, formaldehyde-crosslinked EcFtsZ showed a band 128 kDa recognized by anti-FtsZ antibodies, and a sedimentation friction coefficient (Smax/S20,w) equal to 1.9, while the theoretical sedimentation friction coefficient (Sn/S1) calculated for a triangular trimer was equal to the experimental value. These results suggest that EcFtsZ has two homotrimeric structures (linear and triangular). Finally, we report the aggregation of EcFtsZ at micromolar concentrations of Capsaicin without GTP and Mg2+.

La FtsZ es una proteína del divisoma bacteriano responsable de la formación del anillo Z en la citocinesis. La caracterización de los oligómeros de la proteína FtsZ de Escherichia coli (EcFtsZ) en su estado nativo es un desafío porque la proteína se encuentra como un multioligómero en equilibrio de autoasociación-disociación. Nosotros caracterizamos el estado trimérico de la EcFtsZ a través de técnicas de PAGE nativo, cromatografía de filtración en gel y gradiente de sacarosa combinada con entrecruzamiento químico. Los resultados por filtración indican que el trímero de EcFtsZ tiene una masa molecular de 131 kDa y un coeficiente de fricción por filtración (Rs/Rmin) igual a 1.9, mientras que el coeficiente de fricción por filtración teórico (fn/f1) calculado para un trímero lineal arrojó un valor igual a 1.8 que está muy cercano al valor experimental. Por otro lado, la EcFtsZ entrecruzada con formaldehído presentó una banda de 128 kDa reconocida por anticuerpos anti-FtsZ y un coeficiente de fricción por sedimentación (Smax/S20,w) igual a 1.9, mientras que el coeficiente de fricción por sedimentación teórico (Sn/S1) calculado para un trímero triangular resultó igual a valor experimental. Estos resultados sugieren que la EcFtsZ tiene dos estructuras homotriméricas (lineal y triangular). Finalmente, reportamos la agregación de la EcFtsZ a concentraciones micromolares de Capsaicina sin GTP y Mg2+.