Study of SQ109 analogs binding to mycobacterium MmpL3 transporter using MD simulations and alchemical relative binding free energy calculations.

N-geranyl-N΄-(2-adamantyl)ethane-1,2-diamine (SQ109) is a tuberculosis drug that has high potency against Mycobacterium tuberculosis (Mtb) and may function by blocking cell wall biosynthesis. After the crystal structure of MmpL3 from Mycobacterium smegmatis in complex with SQ109 became available, it was suggested that SQ109 inhibits Mmpl3 mycolic acid transporter. Here, we showed using molecular dynamics (MD) simulations that the binding profile of nine SQ109 analogs with inhibitory potency against Mtb and alkyl or aryl adducts at C-2 or C-1 adamantyl carbon to MmpL3 was consistent with the X-ray structure of MmpL3 - SQ109 complex. We showed that rotation of SQ109 around carbon-carbon bond in the monoprotonated ethylenediamine unit favors two gauche conformations as minima in water and lipophilic solvent using DFT calculations as well as inside the transporter's binding area using MD simulations. The binding assays in micelles suggested that the binding affinity of the SQ109 analogs was increased for the larger, more hydrophobic adducts, which was consistent with our results from MD simulations of the SQ109 analogues suggesting that sizeable C-2 adamantyl adducts of SQ109 can fill a lipophilic region between Y257, Y646, F260 and F649 in MmpL3. This was confirmed quantitatively by our calculations of the relative binding free energies using the thermodynamic integration coupled with MD simulations method with a mean assigned error of 0.74 kcal mol-1 compared to the experimental values.

Consequences of zinc deficiency on zinc localization, taurine transport, and zinc transporters in rat retina.

The colocalization of taurine and zinc transporters (TAUT, ZnTs) has not been explored in retina. Our objective is to evaluate the effect of the intracellular zinc chelator N,N,N,N-tetrakis-(2-pyridylmethyl) ethylenediamine (TPEN) on zinc localization and colocalization TAUT and ZnT-1 (of plasma membrane), 3 (vesicular), and 7 (vesicular and golgi apparatus) in layers of retina by immunohistochemistry. To mark zinc, it was used cell-permeable fluorescent Zinquin ethyl ester. Specific first and secondary antibodies, conjugated with rhodamine or fluorescein-isothiocyanate were used to mark TAUT and ZnTs. The fluorescence results were reported as integrated optical density (IOD). Zinc was detected in all layers of the retina. The treatment with TPEN produced changes in the distribution of zinc in layers of retina less in the outer nuclear layer compared with the control. TAUT was detected in all layers of retina and TPEN chelator produced decrease of IOD in all layers of retina except in the photoreceptor compared with the control. ZnT 1, 3, and 7 were distributed in all retina layers, with more intensity in ganglion cell layer (GCL) and in the layers where there is synaptic connection. For all transporters, the treatment with TPEN produced significant decrease of IOD in layers of retina least in the inner nuclear layer for ZnT1, in the photoreceptor for ZnT3 and in the GCL and outer plexiform layer for ZnT7. The distribution of zinc, TAUT, and ZnTs in the layers of retina is indicative of the interaction of taurine and zinc for the function of the retina and normal operation of said layers. HIGHLIGHTS: Taurine and zinc are two molecules highly concentrated in the retina and with relevant functions in this structure. Maintaining zinc homeostasis in this tissue is necessary for the normal function of the taurine system in the retina. The study of the taurine transporter and the different zinc transporters in the retina (responsible for maintaining adequate levels of taurine and zinc) is relevant and novel, since it is indicative of the interactions between both molecules in this structure.

The 1, 2-ethylenediamine SQ109 protects against tuberculosis by promoting M1 macrophage polarization through the p38 MAPK pathway.

Directly Observed Treatment Short-course (DOTs), is an effective and widely recommended treatment for tuberculosis (TB). The antibiotics used in DOTs, are immunotoxic and impair effector T cells, increasing the risk of re-infections and reactivation. Multiple reports suggest that addition of immune-modulators along with antibiotics improves the effectiveness of TB treatment. Therefore, drugs with both antimicrobial and immunomodulatory properties are desirable. N1-(Adamantan-2-yl)-N2-[(2E)-3,7-dimethylocta-2,6-dien-1-yl]ethane-1,2-diamine (SQ109) is an asymmetric diamine derivative of adamantane, that targets Mycobacterial membrane protein Large 3 (MmpL3). SQ109 dissipates the transmembrane electrochemical proton-gradient necessary for cell-wall biosynthesis and bacterial activity. Here, we examined the effects of SQ109 on host-immune responses using a murine TB model. Our results suggest the pro-inflammatory nature of SQ109, which instigates M1-macrophage polarization and induces protective pro-inflammatory cytokines through the p38-MAPK pathway. SQ109 also promotes Th1 and Th17-immune responses that inhibit the bacillary burden in a murine model of TB. These findings put forth SQ109 as a potential-adjunct to TB antibiotic therapy.

B- and N-doped carbon dots by one-step microwave hydrothermal synthesis: tracking yeast status and imaging mechanism.

BACKGROUND: Carbon dots (CDs) are widely used in cell imaging due to their excellent optical properties, biocompatibility and low toxicity. At present, most of the research on CDs focuses on biomedical application, while there are few studies on the application of microbial imaging. RESULTS: In this study, B- and N-doped carbon dots (BN-CDs) were prepared from citric acid, ethylenediamine, and boric acid by microwave hydrothermal method. Based on BN-CDs labeling yeast, the dead or living of yeast cell could be quickly identified, and their growth status could also be clearly observed. In order to further observe the morphology of yeast cell under different lethal methods, six methods were used to kill the cells and then used BN-CDs to label the cells for imaging. More remarkably, imaging of yeast cell with ultrasound and antibiotics was significantly different from other imaging due to the overflow of cell contents. In addition, the endocytosis mechanism of BN-CDs was investigated. The cellular uptake of BN-CDs is dose, time and partially energy-dependent along with the involvement of passive diffusion. The main mechanism of endocytosis is caveolae-mediated. CONCLUSION: BN-CDs can be used for long-term stable imaging of yeast, and the study provides basic research for applying CDs to microbiol imaging.

Co-delivery of imidazolium Zn(II)salen and Origanum Syriacum essential oil by shrimp chitosan nanoparticles for antimicrobial applications.

This study reports preparation and physicochemical characterization of natural antimicrobials (Origanum Syriacum essential oil (OSEO), shrimp chitosan nanoparticles (CSNPs)) and new imidazolium ionic liquid-supported Zn(II)Salen. These antimicrobials were separately or co-encapsulated by CSNPs to fabricate novel antimicrobial nanoplatforms "NPFs" (OSEO-loaded CSNPs (NPF-1), Zn(II)Salen-loaded CSNPs (NPF-2), and Zn(II)Salen@OSEO-loaded CSNPs (NPF-3)). The finding of loading, encapsulation, and antimicrobial release studies confirm the suitability of CSNPs for nanoencapsulation of Zn(II)Salen and OSEO. All NPFs can significantly suppress the growth of microbial species with performances dependent upon the microbial strain and nanoplatform concentration. The susceptibility of microbes toward new antimicrobials was as follows; Gram-positive bacteria > Gram-negative bacteria > fungi. The amazing physicochemical features of new nanoplatforms and their bioactive ingredients (Zn(II)Salen, OSEO, and CSNPs) signify the importance of our designs for developing a new generation of nanopharmaceuticals supported both natural products and biogenic ionic metal cofactors, targeting the multidrug resistant (MDR) pathogens.

Synergistic effects of type I PRMT and PARP inhibitors against non-small cell lung cancer cells.

BACKGROUND: Non-small cell lung carcinoma (NSCLC) is a leading cause of cancer-related death and represents a major health burden worldwide. Current therapies for NSCLC include chemotherapy, immunotherapy, and targeted molecular agents such as tyrosine kinase inhibitors and epigenetic drugs such as DNA methyltransferase inhibitors. However, survival rates remain low for patients with NSCLC, especially those with metastatic disease. A major cause for therapeutic failure is drug resistance, highlighting the need for novel therapies and combination strategies. Given that epigenetic modulators such as protein arginine methyltransferases (PRMTs) are frequently overexpressed in cancers, PRMT inhibitors are a promising class of cancer therapeutics. We screened a library of epigenetic and anticancer drugs to identify compounds that would synergize with MS023, a type I PRMT inhibitor, in decreasing the viability of methylthioadenosine phosphorylase (MTAP)-negative NSCLC cells. RESULTS: Among 181 compounds, we identified PARP inhibitors (PARPi) as having a strong synergistic interaction with type I PRMT inhibition. The combination of MS023 and the PARP inhibitor BMN-673 (Talazoparib) demonstrated strong synergistic interaction at low nanomolar concentrations in MTAP-negative NSCLC cell lines A549, SK-LU-1 and HCC4006. The re-introduction of MTAP decreased the sensitivity of the combination therapy in A549. The combination therapy resulted in elevated γ-H2AX foci indicating increased DNA damage causing decreased cell viability. Lastly, the combination therapy was effective in PARPi resistant ovarian cancer cells, suggesting that type I PRMT inhibitors could mitigate PARPi resistance, thus potentially having an important clinical impact for cancer treatment. CONCLUSIONS: These findings identify a novel cancer drug combination therapy, which is more potent than the separate single-agent therapies. Thus, combining PARP inhibitors and type I PRMT inhibitors represents a new therapeutic opportunity for MTAP-negative NSCLC and certain cancer cells resistant to PARP inhibitors.

Metabolomics and hormonomics to crack the code of filbert growth.

INTRODUCTION: Plants respond to changes in their environments through hormonal activation of a physiological cascade that redirects metabolic resources and growth. In filberts (Corylus sp.), chelated iron promotes the growth of new shoots but the mechanism(s) are not understood. OBJECTIVES: To use untargeted metabolomics and hormonomics approaches to generate novel hypotheses for the morphoregulatory role of ferric ethylenediamine-N,N'-di-(ortho-hydroxyphenyl) acetic acid (Fe-EDDHA) in filbert shoot organogenesis in vitro. METHODS: Data were generated using previously optimized standardized untargeted metabolomics protocols with time of flight mass spectrometry. Multivariate statistical tools (principal component and partial least squares discriminant analysis) did not detect significant differences. Discovery tools Significance Analysis of Microarrays (SAM), multiple linear regression analysis, Bayesian analysis, logical algorithms, machine learning, synthetic biotransformations, targeted hormonomics, and online resources including MetaboAnalyst were used. RESULTS: Starch/sucrose metabolism and shikimate pathway metabolites were increased. Dose dependent decreases were found in polyphenol metabolism, specifically ellagic acid and its methylated derivative 3,4,3'-tri-O-methylellagic acid. Hormonomics analysis revealed significant differences in phytohormones and their conjugates. FeEDDHA treatment reduced indole-3-acetic acid, abscisic acid, salicylic acid, jasmonic acid conjugates (JA-Trp, JA-Ile, OH-JA) and dihydrozeatinglucoside in regenerating explants. Serotonin (5HT) was decreased in FeEDDHA-treated regenerating tissues while the related metabolite melatonin was increased. Eight phenolic conjugates of 5HT and eight catabolites were affected by FeEDDHA indicating that metabolism to sequester, deactivate and metabolize 5HT was induced by Fe(III). Tryptophan was metabolized through kynurenine but not anthranilate. CONCLUSION: Seven novel hypotheses were generated to guide future studies to understand the regulatory control(s) of shoot organogenesis.

Metabolic engineering of Amycolatopsis japonicum for optimized production of [S,S]-EDDS, a biodegradable chelator.

The actinomycete Amycolatopsis japonicum is the producer of the chelating compound [S,S]-ethylenediamine-disuccinc acid (EDDS). [S,S]-EDDS is an isomer of ethylenediamine-tetraacetic acid (EDTA), an economically important chelating compound that suffers from an extremely poor degradability. Frequent use of the persistent EDTA in various industrial and domestic applications has caused an accumulation of EDTA in soil as well as in aqueous environments. As a consequence, EDTA is the highest concentrated anthropogenic compound present in water reservoirs. The [S,S]-form of EDDS has chelating properties similar to EDTA, however, in contrast to EDTA it is readily biodegradable. In order to compete with the cost-effective chemical synthesis of EDTA, we aimed to optimize the biotechnological production of [S,S]-EDDS in A. japonicum by using metabolic engineering approaches. Firstly, we integrated several copies of the [S,S]-EDDS biosynthetic genes into the chromosome of A. japonicum and replaced the native zinc responsive promoter with the strong synthetic constitutive promoter SP44*. Secondly, we increased the supply of O-phospho-serine, the direct precursor of [S,S]-EDDS. The combination of these approaches together with the optimized fermentation process led to a significant improvement in [S,S]-EDDS up to 9.8 g/L with a production rate of 4.3 mg/h/g DCW.

A Bis-Zn2+ -Pyridyl-Salen-Type Complex Conjugated to the ATP Aptamer: An ATPase-Mimicking Nucleoapzyme.

Catalytic nucleic acids consisting of a bis-Zn2+ -pyridyl-salen-type ([di-ZnII 3,5 bis(pyridinylimino) benzoic acid]) complex conjugated to the ATP aptamer act as ATPase-mimicking catalysts (nucleoapzymes). Direct linking of the Zn2+ complex to the 3'- or 5'-end of the aptamer (nucleoapzymes I and II) or its conjugation to the 3'- or 5'-end of the aptamer through bis-thymidine spacers (nucleoapzymes III and IV) provided a set of nucleoapzymes exhibiting variable catalytic activities. Whereas the separated bis-Zn2+ -pyridyl-salen-type catalyst and the ATP aptamer do not show any noticeable catalytic activity, the 3'-catalyst-modified nucleoapzyme (nucleoapzyme IV) and, specifically, the nucleoapzyme consisting of the catalyst linked to the 3'-position through the spacer (nucleoapzyme III) reveal enhanced catalytic features in relation to the analogous nucleoapzyme substituted at the 5'-position (kcat =4.37 and 6.88 min-1 , respectively). Evaluation of the binding properties of ATP to the different nucleoapzyme and complementary molecular dynamics simulations suggest that the distance separating the active site from the substrate linked to the aptamer binding site controls the catalytic activities of the different nucleoapzymes.

Zn homeostasis in genetic models of Parkinson's disease in Caenorhabditis elegans.

While the underlying mechanisms of Parkinson's disease (PD) are still insufficiently studied, a complex interaction between genetic and environmental factors is emphasized. Nevertheless, the role of the essential trace element zinc (Zn) in this regard remains controversial. In this study we altered Zn balance within PD models of the versatile model organism Caenorhabditis elegans (C. elegans) in order to examine whether a genetic predisposition in selected genes with relevance for PD affects Zn homeostasis. Protein-bound and labile Zn species act in various areas, such as enzymatic catalysis, protein stabilization pathways and cell signaling. Therefore, total Zn and labile Zn were quantitatively determined in living nematodes as individual biomarkers of Zn uptake and bioavailability with inductively coupled plasma tandem mass spectrometry (ICP-MS/MS) or a multi-well method using the fluorescent probe ZinPyr-1. Young and middle-aged deletion mutants of catp-6 and pdr-1, which are orthologues of mammalian ATP13A2 (PARK9) and parkin (PARK2), showed altered Zn homeostasis following Zn exposure compared to wildtype worms. Furthermore, age-specific differences in Zn uptake were observed in wildtype worms for total as well as labile Zn species. These data emphasize the importance of differentiation between Zn species as meaningful biomarkers of Zn uptake as well as the need for further studies investigating the role of dysregulated Zn homeostasis in the etiology of PD.

Improvement of Asparagine Ethylenediamines as Anti-malarial Plasmodium-Selective Proteasome Inhibitors.

The Plasmodium proteasome (Pf20S) emerged as a target for antimalarials. Pf20S inhibitors are active at multiple stages of the parasite life cycle and synergize with artemisinins, suggesting that Pf20S inhibitors have potential to be prophylactic, therapeutic, and transmission blocking as well as are useful for combination therapy. We recently reported asparagine ethylenediamines (AsnEDAs) as immunoproteasome inhibitors and modified AsnEDAs as selective Pf20S inhibitors. Here, we report further a structure-activity relationship study of AsnEDAs for selective inhibition of Pf20S over human proteasomes. Additionally, we show new mutation that conferred resistance to AsnEDAs and collateral sensitivity to an inhibitor of the Pf20S ß2 subunit, the same as previously identified resistant mutation. This resistance could be overcome through the use of the structure-guided inhibitor design. Collateral sensitivity to inhibitors among respective proteasome subunits underscores the potential value of treating malaria with combinations of inhibitors of different proteasome subunits to minimize the emergence of drug resistance.

Surface charge controlled nucleoli selective staining with nanoscale carbon dots.

Organelle selective imaging can reveal structural and functional characters of cells undergoing external stimuli, and is considered critical in revealing biological fundamentals, designing targeted delivery system, and screening potential drugs and therapeutics. This paper describes the nucleoli targeting ability of nanoscale carbon dots (including nanodiamond) that are hydrothermally made with controlled surface charges. The surface charges of carbon dots are controlled in the range of -17.9 to -2.84 mV by changing the molar ratio of two precursors, citric acid (CA) and ethylenediamine (EDA). All carbon dots samples show strong fluorescence under wide excitation wavelength, and samples with both negative and positve charges show strong fluorescent contrast from stained nucleoli. The nucleoli selective imaging of live cell has been confirmed with Hoechst staining and nucleoli specific staining (SYTO RNA-select green), and is explained as surface charge heterogeneity on carbon dots. Carbon dots with both negative and positive charges have better ability to penetrate cell and nucleus membranes, and the charge heterogeneity helps carbon dots to bind preferentially to nucleoli, where the electrostatic environment is favored.

Understanding and Modulating Metalloenzymes with Unnatural Amino Acids, Non-Native Metal Ions, and Non-Native Metallocofactors.

Metalloproteins set the gold standard for performing important functions, including catalyzing demanding reactions under mild conditions. Designing artificial metalloenzymes (ArMs) to catalyze abiological reactions has been a major endeavor for many years, but most ArM activities are far below those of native enzymes, making them unsuitable for most pratical applications. A critical step to advance the field is to fundamentally understand what it takes to not only confer but also fine-tune ArM activities so they match those of native enzymes. Indeed, only once we can freely modulate ArM activity to rival (or surpass!) natural enzymes can the potential of ArMs be fully realized. A key to unlocking ArM potential is the observation that one metal primary coordination sphere can display a range of functions and levels of activity, leading to the realization that secondary coordination sphere (SCS) interactions are critically important. However, SCS interactions are numerous, long-range, and weak, making them very difficult to reproduce in ArMs. Furthermore, natural enzymes are tied to a small set of biologically available functional moieties from canonical amino acids and physiologically available metal ions and metallocofactors, severely limiting the chemical space available to probe and tune ArMs. In this Account, we summarize the use of unnatural amino acids (UAAs) and non-native metal ions and metallocofactors by our group and our collaborators to probe and modulate ArM functions. We incorporated isostructural UAAs in a type 1 copper (T1Cu) protein azurin to provide conclusive evidence that axial ligand hydrophobicity is a major determinant of T1Cu redunction potential ( E°'). Closely related work from other groups are also discussed. We also probed the role of protein backbone interactions that cannot be altered by standard mutagenesis by replacing the peptide bond with an ester linkage. We used insight gained from these studies to tune the E°' of azurin across the entire physiological range, the broadest range ever achieved in a single metalloprotein. Introducing UAA analogues of Tyr into ArM models of heme-copper oxidase (HCO) revealed a linear relationship between p Ka, E°', and activity. We also substituted non-native hemes and non-native metal ions for their native equivalents in these models to resolve several issues that were intractable in native HCOs and the closely related nitric oxide reductases, such as their roles in modulating substrate affinity, electron transfer rate, and activity. We incorporated abiological cofactors such as ferrocene and Mn(salen) into azurin and myoglobin, respectively, to stabilize these inorganic and organometallic compounds in water, confer abiological functions, tune their E°' and activity through SCS interactions, and show that the approach to metallocofactor anchoring and orientation can tune enantioselectivity and alter function. Replacing Cu in azurin with non-native Fe or Ni can impart novel activities, such as superoxide reduction and C-C bond formation. While progress was made, we have identified only a small fraction of the interactions that can be generally applied to ArMs to fine-tune their functions. Because SCS interactions are subtle and heavily interconnected, it has been difficult to characterize their effects quantitatively. It is vital to develop spectroscopic and computational techniques to detect and quantify their effects in both resting states and catalytic intermediates.

Comparative Response of Cardiomyocyte ZIPs and ZnTs to Extracellular Zinc and TPEN.

Intracellular zinc concentrations are tightly regulated by the coordinated regulation of ZIPs and ZnTs. Very little is known about the regulation of these transporters in cardiomyocytes, in response to extracellular zinc. Adult rat cardiomyocytes express ZnTs 1, 2, 5, and 9, in addition to ZIPs 1, 2, 3, 6, 7, 9, 10, 11, 13, and 14. We have determined the intracellular free zinc levels using Zinpyr-1 fluorescence and studied response of ZIP and ZnT mRNA by real-time PCR to the changes in extracellular zinc and TPEN in adult rat ventricular myocytes. TPEN downregulated ZnT1, ZnT2, and ZIP11 mRNAs but upregulated ZnT5, ZIP2, ZIP7, ZIP10, ZIP13, and ZIP14 mRNAs. Zinc supplementation upregulated ZnT1, ZnT2 mRNA but downregulated ZnT5, ZIP1, ZIP2, ZIP3, ZIP7, ZIP9, and ZIP10 mRNA. The negative regulation of ZIPs by zinc excess can be explained in terms of zinc homeostasis as these transporters may act to protect cells from zinc over accumulation by reducing zinc influx when the extracellular concentration of zinc is high. Similarly, the ZnT expression appears to be regulated to avoid loss of zinc from the intracellular milieu, under zinc-deficient conditions.

Enhancement of phytoextraction by Taiwanese chenopod and Napier grass by soapnut saponin and EDDS additions.

Employment of biosurfactants and biodegradable chelants could further promote sustainability of soil and groundwater remediation tasks. Biosurfactant (soapnut saponin) and biodegrading chelants (ethylenediamine-N,N'-disuccinic acid (EDDS)) were employed to enhance the phytoextraction by native Taiwanese chenopod (Chenopodium formosanum Koidz.), Napier grass (Pennisetum purpureum) cultivar Taishi No. 4, and soapwort (Saponaria officinalis). Ethylene diamine tetraacetic acid (EDTA) was also employed as the control. Contaminated soils as silty clay loam texture was collected from a defunct rice paddy, containing chromium (Cr), cadium (Cd), and copper (Cu). Addition of both soapnut saponin and EDDS proportionally increased bioaccumulation factors (BCFs) of aboveground biomass for all three plants. Taiwanese chenopod demonstrated the best BCF values among three plants, with BCF increased from 0.76 to 2.6 and 1.3 for Cu under the presence of the highest dosages of EDDS and saponin. Plant aboveground biomass did exhibit negative correlation toward biomass metal concentrations. Presence of saponin did exhibit the least negative slopes among the correlations of all three additives for three plants. Taiwanese chenopod did exhibit the least negative slopes among the correlations of all three additives for three plants. Above observations suggested that saponin may have some protection for plants, especially for Napier grass. Taiwanese chenopod could possess more tolerance toward heavy metals than Napier grass does.

Tryptophan carbon dots and their ability to cross the blood-brain barrier.

Drug traversal across the blood-brain barrier has come under increasing scrutiny recently, particularly concerning the treatment of sicknesses, such as brain cancer and Alzheimer's disease. Most therapies and medicines are limited due to their inability to cross this barrier, reducing treatment options for maladies affecting the brain. Carbon dots show promise as drug carriers, but they experience the same limitations regarding crossing the blood-brain barrier as many small molecules do. If carbon dots can be prepared from a precursor that can cross the blood-brain barrier, there is a chance that the remaining original precursor molecule can attach to the carbon dot surface and lead the system into the brain. Herein, tryptophan carbon dots were synthesized with the strategy of using tryptophan as an amino acid for crossing the blood-brain barrier via LAT1 transporter-mediated endocytosis. Two types of carbon dots were synthesized using tryptophan and two different nitrogen dopants: urea and 1,2-ethylenediamine. Carbon dots made using these precursors show excitation wavelength-dependent emission, low toxicity, and have been observed inside the central nervous system of zebrafish (Danio rerio). The proposed mechanism for these carbon dots abilities to cross the blood-brain barrier concerns residual tryptophan molecules which attach to the carbon dots surface, enabling them to be recognized by the LAT1 transporter. The role of carbon dots for transport open promising avenues for drug delivery and imaging in the brain.

Crystal Structures of Membrane Transporter MmpL3, an Anti-TB Drug Target.

Despite intensive efforts to discover highly effective treatments to eradicate tuberculosis (TB), it remains as a major threat to global human health. For this reason, new TB drugs directed toward new targets are highly coveted. MmpLs (Mycobacterial membrane proteins Large), which play crucial roles in transporting lipids, polymers and immunomodulators and which also extrude therapeutic drugs, are among the most important therapeutic drug targets to emerge in recent times. Here, crystal structures of mycobacterial MmpL3 alone and in complex with four TB drug candidates, including SQ109 (in Phase 2b-3 clinical trials), are reported. MmpL3 consists of a periplasmic pore domain and a twelve-helix transmembrane domain. Two Asp-Tyr pairs centrally located in this domain appear to be key facilitators of proton-translocation. SQ109, AU1235, ICA38, and rimonabant bind inside the transmembrane region and disrupt these Asp-Tyr pairs. This structural data will greatly advance the development of MmpL3 inhibitors as new TB drugs.

Substituted effect on some water-soluble Mn(II) salen complexes: DNA binding, cytotoxicity, molecular docking, DFT studies and theoretical IR & UV studies.

Based on the importance of central metal complexes to interact with DNA, in this research focused on synthesis of some new water soluble Mn(II) complexes 1-4 which modified substituted in ligand at the same position with N, Me, H, and Cl. These complexes were isolated and characterized by elemental analyses, FT-IR, electrospray ionization mass spectrometry (ESI-MS) and UV-vis spectroscopy. DNA binding studies had been studied by using circular dichroism (CD) spectroscopy, UV-vis absorption spectroscopy, cyclic voltammetry (CV), viscosity measurements, emission spectroscopy and gel electrophoresis which proposed the metal buildings go about as effective DNA binders were studied in the presence of Fish-DNA (FS-DNA) which showed the highest binding affinity to DNA with hydrophobic and electron donating substituent. Cell toxicity assays against two human leukemia (Jurkat) and breast cancer (MCF-7) cell lines showed that the complex 3 exhibited a remarkable effects equal to a famous anticancer drug, cisplatin that high cytotoxic activity strongly depend on the hydrophobic substituted ligand. In the theoretical part, density functional theory (DFT) was performed to optimize the geometry of complexes through IR and UV spectra of the complexes that ligand substitution did not affect the geometry and theoretical IR and UV spectra showed good resemblance to the experimental data. The docking studies calculated the lowest-energy between complexes and DNA with the minor grooves mode.

Zinc-Chelating Small Molecules Preferentially Accumulate and Function within Pancreatic ß Cells.

Diabetes is a hyperglycemic condition characterized by pancreatic ß-cell dysfunction and depletion. Whereas methods for monitoring ß-cell function in vivo exist, methods to deliver therapeutics to ß cells are lacking. We leveraged the rare ability of ß cells to concentrate zinc to preferentially trap zinc-binding molecules within ß cells, resulting in ß-cell-targeted compound delivery. We determined that zinc-rich ß cells and islets preferentially accumulated TSQ (6-methoxy-8-p-toluenesulfonamido-quinoline) in a zinc-dependent manner compared with exocrine pancreas. Next, we asked whether appending a zinc-chelating moiety onto a ß-cell replication-inducing compound was sufficient to confer preferential ß-cell accumulation and activity. Indeed, the hybrid compound preferentially accumulated within rodent and human islets in a zinc-dependent manner and increased the selectivity of replication-promoting activity toward ß cells. These data resolve the fundamental question of whether intracellular accumulation of zinc-chelating compounds is influenced by zinc content. Furthermore, application of this principle yielded a proof-of-concept method for ß-cell-targeted drug delivery and bioactivity.