scholarly journals Discovery of Novel Oral Protein Synthesis Inhibitors of Mycobacterium tuberculosis That Target Leucyl-tRNA Synthetase

2016 ◽  
Vol 60 (10) ◽  
pp. 6271-6280 ◽  
Author(s):  
Andrés Palencia ◽  
Xianfeng Li ◽  
Wei Bu ◽  
Wai Choi ◽  
Charles Z. Ding ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Mycobacterium Tuberculosis ◽  
Cell Activity ◽  
Trna Synthetase ◽  
Protein Synthesis Inhibitor ◽  
Drug Resistant ◽  
Protein Synthesis Inhibitors ◽  
Synthesis Inhibitor ◽  
Content Type

ABSTRACTThe recent development and spread of extensively drug-resistant and totally drug-resistant resistant (TDR) strains ofMycobacterium tuberculosishighlight the need for new antitubercular drugs. Protein synthesis inhibitors have played an important role in the treatment of tuberculosis (TB) starting with the inclusion of streptomycin in the first combination therapies. Although parenteral aminoglycosides are a key component of therapy for multidrug-resistant TB, the oxazolidinone linezolid is the only orally available protein synthesis inhibitor that is effective against TB. Here, we show that small-molecule inhibitors of aminoacyl-tRNA synthetases (AARSs), which are known to be excellent antibacterial protein synthesis targets, are orally bioavailable and effective againstM. tuberculosisin TB mouse infection models. We applied the oxaborole tRNA-trapping (OBORT) mechanism, which was first developed to target fungal cytoplasmic leucyl-tRNA synthetase (LeuRS), toM. tuberculosisLeuRS. X-ray crystallography was used to guide the design of LeuRS inhibitors that have good biochemical potency and excellent whole-cell activity againstM. tuberculosis. Importantly, their good oral bioavailability translates intoin vivoefficacy in both the acute and chronic mouse models of TB with potency comparable to that of the frontline drug isoniazid.

scholarly journals Pharmacokinetic and Pharmacodynamic Evaluation of P-873 versus Klebsiella pneumoniae in a Neutropenic Murine Thigh Infection Model

2013 ◽  
Vol 57 (4) ◽  
pp. 1971-1973 ◽  
Author(s):  
Lucinda M. Lamb ◽  
Jared L. Crandon ◽  
David P. Nicolau
Keyword(s):  
Protein Synthesis ◽  
Klebsiella Pneumoniae ◽  
Infection Model ◽  
Protein Synthesis Inhibitors ◽  
Content Type ◽  
Pharmacokinetic Properties

ABSTRACTP-873 is a novel compound in the RX-04 pyrrolocytosine series of protein synthesis inhibitors currently under development by Rib-X Pharmaceuticals. We evaluated the pharmacodynamic and pharmacokinetic properties of this compound againstKlebsiella pneumoniaeusing a murine neutropenic thigh infection model. P-873 demonstrated potent and rapidin vivoactivity against this organism with enhanced penetration and duration of exposure in thigh tissue.

scholarly journals ON THE MECHANISM OF ADAPTATION TO PROTEIN SYNTHESIS INHIBITORS BY TETRAHYMENA

1974 ◽  
Vol 62 (3) ◽  
pp. 707-716 ◽  
Author(s):  
Charles T. Roberts ◽  
Eduardo Orias
Keyword(s):  
Protein Synthesis ◽  
Cell Division ◽  
Protein Synthesis Inhibitor ◽  
Protein Synthesis Inhibitors ◽  
Cellular Functions ◽  
Synthesis Inhibitor ◽  
Experimental Conditions ◽  
Cellular Machinery ◽  
Time Required ◽  
Sublethal Concentrations

Tetrahymena is able to adapt to the presence of sublethal concentrations of many drugs which inhibit a wide variety of cellular functions. In spite of the generality of this phenomenon in Tetrahymena, the mechanism of adaptation at the cellular and molecular levels is unknown. This study deals mainly with adaptation to the protein synthesis inhibitors, cycloheximide and emetine. The physiological response of Tetrahymena to sublethal concentrations of these drugs is an immediate cessation of cell division for a period of time dependent on the drug concentration, followed by an abrupt resumption of exponential growth at a constant rate. By measuring the length of the growth lags under a variety of experimental conditions, we have confirmed several observations made by Frankel and coworkers, and provide evidence for two new phenomena associated with adaptation to cycloheximide: (a) adaptation to cycloheximide also results in adaptation of cells to emetine, another protein synthesis inhibitor not closely related structurally to cycloheximide. We have termed this phenomenon cross adaptation, (b) exposure to concentrations of cycloheximide too low to cause any growth lags or inhibition of protein synthesis significantly shortens the time required by cells to adapt to higher concentrations of cycloheximide. We have termed this phenomenon facilitation. Facilitation shows some degree of specificity in that facilitation with cycloheximide has no effect on adaptation to emetine. From this, we infer the existence of two distinct systems involved in adaptation to cycloheximide, one of which shows a higher degree of specificity towards cycloheximide than the other. We also show that transfer of adapted or facilitated cells to drug-free medium results in a gradual but complete resensitization. The kinetics of resensitization suggest that the cellular machinery responsible for adaptation and facilitation does not leave the cell, but is simply diluted out during cell division.

Corticotropin-Releasing Factor Produces a Protein Synthesis–Dependent Long-Lasting Potentiation in Dentate Gyrus Neurons

2000 ◽  
Vol 83 (1) ◽  
pp. 343-349 ◽  
Author(s):  
Hai L. Wang ◽  
Li Y. Tsai ◽  
Eminy H. Y. Lee
Keyword(s):  
Protein Synthesis ◽  
Synaptic Transmission ◽  
Dentate Gyrus ◽  
Late Phase ◽  
Long Term Potentiation ◽  
Corticotropin Releasing Factor ◽  
Rat Hippocampus ◽  
Protein Synthesis Inhibitor ◽  
Synthesis Inhibitor

Corticotropin-releasing factor (CRF) was shown to produce a long-lasting potentiation of synaptic efficacy in dentate gyrus neurons of the rat hippocampus in vivo. This potentiation was shown to share some similarities with tetanization-induced long-term potentiation (LTP). In the present study, we further examined the mechanism underlying CRF-induced long-lasting potentiation in rat hippocampus in vivo. Results indicated that the RNA synthesis inhibitor actinomycin-D, at a concentration that did not change basal synaptic transmission alone (5 μg), significantly decreased CRF-induced potentiation. Similarly, the protein synthesis inhibitor emetine, at a concentration that did not affect hippocampal synaptic transmission alone (5 μg), also markedly inhibited CRF-induced potentiation. These results suggest that like the late phase of LTP, CRF-induced long-lasting potentiation also critically depend on protein synthesis. Further, prior maximum excitation of dentate gyrus neurons with tetanization occluded further potentiation of these neurons produced by CRF and vise versa. Moreover, quantitative reverse transcription-polymerase chain reaction analysis revealed that CRF mRNA level in the dentate gyrus was significantly increased 1 h after LTP recording. Together with our previous findings that CRF antagonist dose-dependently diminishes tetanization-induced LTP, these results suggest that both CRF-induced long-lasting potentiation and tetanization-induced LTP require protein synthesis and that CRF neurons are possibly involved in the neural circuits underlying LTP.

Drug inhibition of memory formation in chickens II. Short-term memory

1971 ◽  
Vol 178 (1053) ◽  
pp. 455-464 ◽  
Keyword(s):  
Protein Synthesis ◽  
Sodium Pump ◽  
Short Term Memory ◽  
Memory Loss ◽  
Protein Synthesis Inhibitor ◽  
Protein Synthesis Inhibitors ◽  
Short Term ◽  
Synthesis Inhibitor ◽  
Term Memory

1. Memory in day-old-chickens during the first few hours after learning can be made to decline by the prior intracranial injection of two classes of drugs. 2. Sodium pump inhibitors in increasing doses cause increasingly rapid loss of memory. 3. Protein synthesis inhibitors in increasing doses attain a maximum potency in causing memory decline and the rate may not be further accelerated by higher doses. 4. Adding a sodium pump inhibitor to the inhibition of protein synthesis increases memory loss. 5. Adding a protein synthesis inhibitor to a sodium pump inhibitor causes no further loss. 6. Therefore within a few minutes of learning a short-term memory of limited time span but independent of protein synthesis becomes supplemented and eventually replaced by a long-term storage requiring protein synthesis. The amount of long-term store is set by the amount of short-term memory. 7. The short-term store could be directly dependent on post-activation enhancement of Na + extrusion from neurons. Some physiological mechanisms by which this could be achieved and how this might activate protein synthesis are discussed.

scholarly journals In VitroandIn VivoActivities of the Nitroimidazole TBA-354 against Mycobacterium tuberculosis

2014 ◽  
Vol 59 (1) ◽  
pp. 136-144 ◽  
Author(s):  
A. M. Upton ◽  
S. Cho ◽  
T. J. Yang ◽  
Y. Kim ◽  
Y. Wang ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Pharmacokinetic Profile ◽  
Multidrug Resistant ◽  
Phase Iii ◽  
Drug Resistant ◽  
Next Generation ◽  
Content Type ◽  
Resistant Tuberculosis

ABSTRACTNitroimidazoles are a promising new class of antitubercular agents. The nitroimidazo-oxazole delamanid (OPC-67683, Deltyba) is in phase III trials for the treatment of multidrug-resistant tuberculosis, while the nitroimidazo-oxazine PA-824 is entering phase III for drug-sensitive and drug-resistant tuberculosis. TBA-354 (SN31354[(S)-2-nitro-6-((6-(4-trifluoromethoxy)phenyl)pyridine-3-yl)methoxy)-6,7-dihydro-5H-imidazo[2,1-b][1,3]oxazine]) is a pyridine-containing biaryl compound with exceptional efficacy against chronic murine tuberculosis and favorable bioavailability in preliminary rodent studies. It was selected as a potential next-generation antituberculosis nitroimidazole following an extensive medicinal chemistry effort. Here, we further evaluate the pharmacokinetic properties and activity of TBA-354 againstMycobacterium tuberculosis. TBA-354 is narrow spectrum and bactericidalin vitroagainst replicating and nonreplicatingMycobacterium tuberculosis, with potency similar to that of delamanid and greater than that of PA-824. The addition of serum protein or albumin does not significantly alter this activity. TBA-354 maintains activity againstMycobacterium tuberculosisH37Rv isogenic monoresistant strains and clinical drug-sensitive and drug-resistant isolates. Spontaneous resistant mutants appear at a frequency of 3 × 10−7.In vitrostudies andin vivostudies in mice confirm that TBA-354 has high bioavailability and a long elimination half-life.In vitrostudies suggest a low risk of drug-drug interactions. Low-dose aerosol infection models of acute and chronic murine tuberculosis reveal time- and dose-dependentin vivobactericidal activity that is at least as potent as that of delamanid and more potent than that of PA-824. Its superior potency and pharmacokinetic profile that predicts suitability for once-daily oral dosing suggest that TBA-354 be studied further for its potential as a next-generation nitroimidazole.

scholarly journals Synthetic Lethality Reveals Mechanisms of Mycobacterium tuberculosis Resistance to β-Lactams

mBio ◽  
2014 ◽  
Vol 5 (5) ◽  
Author(s):  
Shichun Lun ◽  
David Miranda ◽  
Andre Kubler ◽  
Haidan Guo ◽  
Mariama C. Maiga ◽  
...  
Keyword(s):  
Cell Wall ◽  
Mycobacterium Tuberculosis ◽  
Synthetic Lethality ◽  
Multidrug Resistant ◽  
Cell Wall Biosynthesis ◽  
Drug Resistant ◽  
Content Type ◽  
Innate Resistance ◽  
Extensively Drug Resistant

ABSTRACT Most β-lactam antibiotics are ineffective against Mycobacterium tuberculosis due to the microbe’s innate resistance. The emergence of multidrug-resistant (MDR) and extensively drug-resistant (XDR) strains has prompted interest to repurpose this class of drugs. To identify the genetic determinants of innate β-lactam resistance, we carried out a synthetic lethality screen on a transposon mutant library for susceptibility to imipenem, a carbapenem β-lactam antibiotic. Mutations in 74 unique genes demonstrated synthetic lethality. The majority of mutations were in genes associated with cell wall biosynthesis. A second quantitative real-time PCR (qPCR)-based synthetic lethality screen of randomly selected mutants confirmed the role of cell wall biosynthesis in β-lactam resistance. The global transcriptional response of the bacterium to β-lactams was investigated, and changes in levels of expression of cell wall biosynthetic genes were identified. Finally, we validated these screens in vivo using the MT1616 transposon mutant, which lacks a functional acyl-transferase gene. Mice infected with the mutant responded to β-lactam treatment with a 100-fold decrease in bacillary lung burden over 4 weeks, while the numbers of organisms in the lungs of mice infected with wild-type bacilli proliferated. These findings reveal a road map of genes required for β-lactam resistance and validate synthetic lethality screening as a promising tool for repurposing existing classes of licensed, safe, well-characterized antimicrobials against tuberculosis. IMPORTANCE The global emergence of multidrug-resistant and extensively drug-resistant M. tuberculosis strains has threatened public health worldwide, yet the pipeline of new tuberculosis drugs under development remains limited. One strategy to cope with the urgent need for new antituberculosis agents is to repurpose existing, approved antibiotics. The carbapenem class of β-lactam antibiotics has been proposed as one such class of drugs. Our study identifies molecular determinants of innate resistance to β-lactam drugs in M. tuberculosis, and we demonstrate that functional loss of one of these genes enables successful treatment of M. tuberculosis with β-lactams in the mouse model.

scholarly journals Evidence for Different Contributions of Archaea and Bacteria to the Ammonia-Oxidizing Potential of Diverse Oregon Soils

2010 ◽  
Vol 76 (23) ◽  
pp. 7691-7698 ◽  
Author(s):  
Anne E. Taylor ◽  
Lydia H. Zeglin ◽  
Sandra Dooley ◽  
David D. Myrold ◽  
Peter J. Bottomley
Keyword(s):  
Protein Synthesis ◽  
Protein Synthesis Inhibitor ◽  
Ammonia Oxidizing Bacteria ◽  
Ammonia Monooxygenase ◽  
Bacterial Protein ◽  
Protein Synthesis Inhibitors ◽  
Synthesis Inhibitor ◽  
Ammonia Oxidizing Archaea ◽  
Pasture Soil ◽  
Bacterial Protein Synthesis

ABSTRACT A method was developed to determine the contributions of ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) to the nitrification potentials (NPs) of soils taken from forest, pasture, cropped, and fallowed (19 years) lands. Soil slurries were exposed to acetylene to irreversibly inactivate ammonia monooxygenase, and upon the removal of acetylene, the recovery of nitrification potential (RNP) was monitored in the presence and absence of bacterial or eukaryotic protein synthesis inhibitors. For unknown reasons, and despite measureable NPs, RNP did not occur consistently in forest soil samples; however, pasture, cropped, and fallowed soil RNPs commenced after lags that ranged from 12 to 30 h after acetylene removal. Cropped soil RNP was completely prevented by the bacterial protein synthesis inhibitor kanamycin (800 μg/ml), whereas a combination of kanamycin plus gentamicin (800 μg/ml each) only partially prevented the RNP (60%) of fallowed soils. Pasture soil RNP was completely insensitive to either kanamycin, gentamicin, or a combination of the two. Unlike cropped soil, pasture and fallowed soil RNPs occurred at both 30�C and 40�C and without supplemental NH4 + (≤10 μM NH4 + in solution), and pasture soil RNP demonstrated ∼50% insensitivity to 100 μM allyl thiourea (ATU). In addition, fallowed and pasture soil RNPs were insensitive to the fungal inhibitors nystatin and azoxystrobin. This combination of properties suggests that neither fungi nor AOB contributed to pasture soil RNP and that AOA were responsible for the RNP of the pasture soils. Both AOA and AOB may contribute to RNP in fallowed soil, while RNP in cropped soils was dominated by AOB.

scholarly journals Structure-Activity Relationships of Wollamide Cyclic Hexapeptides with Activity against Drug-Resistant and Intracellular Mycobacterium tuberculosis

2019 ◽  
Vol 63 (3) ◽  
Author(s):  
Zeinab G. Khalil ◽  
Timothy A. Hill ◽  
Luis M. De Leon Rodriguez ◽  
Rink-Jan Lohman ◽  
Huy N. Hoang ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Mammalian Cells ◽  
Antimycobacterial Activity ◽  
Drug Resistant ◽  
Amino Acid Residues ◽  
Content Type ◽  
Cyclic Hexapeptides ◽  
Rats And Mice

ABSTRACT Wollamides are cyclic hexapeptides, recently isolated from an Australian soil Streptomyces isolate, that exhibit promising in vitro antimycobacterial activity against Mycobacterium bovis Bacille Calmette Guérin without displaying cytotoxicity against a panel of mammalian cells. Here, we report the synthesis and antimycobacterial activity of 36 new synthetic wollamides, collated with all known synthetic and natural wollamides, to reveal structure characteristics responsible for in vitro growth-inhibitory activity against Mycobacterium tuberculosis (H37Rv, H37Ra, CDC1551, HN878, and HN353). The most potent antimycobacterial wollamides were those where residue VI d-Orn (wollamide B) was replaced by d-Arg (wollamide B1) or d-Lys (wollamide B2), with all activity being lost when residue VI was replaced by Gly, l-Arg, or l-Lys (wollamide B3). Substitution of other amino acid residues mainly reduced or ablated antimycobacterial activity. Significantly, whereas wollamide B2 was the most potent in restricting M. tuberculosis in vitro, wollamide B1 restricted M. tuberculosis intracellular burden in infected macrophages. Wollamide B1 synergized with pretomanid (PA-824) in inhibiting M. tuberculosis in vitro growth but did not antagonize prominent first- and second-line tuberculosis antibiotics. Furthermore, wollamide B1 exerted bactericidal activity against nonreplicating M. tuberculosis and impaired growth of multidrug- and extensively drug-resistant clinical isolates. In vivo pharmacokinetic profiles for wollamide B1 in rats and mice encourage further optimization of the wollamide pharmacophore for in vivo bioavailability. Collectively, these observations highlight the potential of the wollamide antimycobacterial pharmacophore.

scholarly journals Experience-specific anterograde amnesia: memory reacquisition deficit phenomenon and its characterization in the vertebrate learning model

2018 ◽  
Author(s):  
A. A. Tiunova ◽  
D. V. Bezryadnov ◽  
D.R. Gaeva ◽  
V.S. Solodovnikov ◽  
K.V. Anokhin
Keyword(s):  
Protein Synthesis ◽  
Nmda Receptor ◽  
Conditioned Avoidance ◽  
Anterograde Amnesia ◽  
Nmda Receptor Antagonist ◽  
Protein Synthesis Inhibitor ◽  
Avoidance Task ◽  
Protein Synthesis Inhibitors ◽  
Synthesis Inhibitor ◽  
Specific Memory

AbstractA common assumption from experiments that interfere with memory consolidation is that the resultant amnesia returns the brain of an animal to a tabula rasa state with respect to disturbed experience. However, recent studies in terrestrial snail classical conditioning revealed an odd phenomenon: animals were unable to relearn conditioned avoidance of specific food after this memory had been impaired by protein-synthesis inhibitors or N-methyl-D-aspartate (NMDA) receptor antagonists. Here we examined whether such specific memory reacquisition deficit can also be observed in vertebrate learning. We trained day-old chicks in a one-trial passive avoidance task by presenting them a bead of a specific color covered with a repellent substance, methyl anthranilate. Training was preceded by administration of the protein synthesis inhibitor anisomycin or the NMDA receptor antagonist MK-801. Both drugs produced permanent amnesia, and no spontaneous recovery of memory was observed. A second training was given to the amnestic animals either using a bead of the same color (retraining) or a new color (novel training). The interval between the first and second training was 2 or 24 h, and the retention test was given from 30 min to 48 h after the second training. Retraining of the amnestic chicks with the bead that was presented during the initial training failed to produce new avoidance memory for this stimulus at all the between-training and training-to-test intervals. This memory reacquisition deficit was specific and was not transferred to a new conditioned stimulus, which was readily learned. We suggest that such pharmacologically induced experience-specific anterograde amnesia might reflect general properties of normal memory allocation, and we discuss its possible neural bases.

scholarly journals Circadian rhythm from the eye of Aplysia: temperature compensation of the effects of protein synthesis inhibitors

1980 ◽  
Vol 84 (1) ◽  
pp. 1-15
Author(s):  
J. W. Jacklet
Keyword(s):  
Protein Synthesis ◽  
Circadian Rhythm ◽  
Circadian Clock ◽  
Culture Medium ◽  
Protein Synthesis Inhibitor ◽  
Dependent Manner ◽  
Protein Synthesis Inhibitors ◽  
Response Curves ◽  
Synthesis Inhibitor ◽  
Maximum Phase

1. The circadian rhythm of compound action potentials (CAP) frequency recorded from the isolated eye of Aplysia in culture medium and darkness was subjected to step and pulse treatments with anisomycin, a protein synthesis inhibitor. 2. The step application of anisomycin and its continued presence in the culture medium lengthened the period of the rhythm in a dose-dependent manner. At 10(−8) M the period was increased from the normal 26.5 h to about 28 h and at 10(−7) M the period was lengthened to 31 h or longer. At 10(−6) M the rhythm was suppressed but the CAP activity continued without the cyclic variations in CAP frequency. 3. Six-hour pulses of anisomycin at 10(−6) M caused phase-dependent phase-shifts of the rhythm. Maximum phase delays of 15 h were obtained at CT (circadian time) 2 and maximum phase advances of 4 h were obtained at CT 6. The phase response curves at 12, 15 and 17 degrees C were essentially identical. 4. Anisomycin appears to act rather selectively on the circadian clock mechanism. It does not alter the CAP amplitude and duration and it does not alter the bursting pacemaker mechanism of the optic nerve CAP or central neurones. 5. The results support the hypothesis that the synthesis of a protein or polypeptide on eucaryotic ribosomes is an essential part of the circadian clock timing mechanism. The sensitivity of the clock to anisomycin is the same at three different temperatures (12, 15 and 17 degrees C) within the physiological range of temperatures for Aplysia, as expected for a clock whose period length is temperature compensated (Q10 1.02) over that same range. 6. At the critical phases of CT 1-4, anisomycin pulses often caused unusual perturbations of the rhythm. These effects are consistent with the hypothesis that the circadian rhythm is a multioscillator system.

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