1
|
Rowaiye AB, Ogugua AJ, Ibeanu G, Bur D, Asala MT, Ogbeide OB, Abraham EO, Usman HB. Identifying potential natural inhibitors of Brucella melitensis Methionyl-tRNA synthetase through an in-silico approach. PLoS Negl Trop Dis 2022; 16:e0009799. [PMID: 35312681 PMCID: PMC8970508 DOI: 10.1371/journal.pntd.0009799] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Revised: 03/31/2022] [Accepted: 02/16/2022] [Indexed: 12/12/2022] Open
Abstract
Background Brucellosis is an infectious disease caused by bacteria of the genus Brucella. Although it is the most common zoonosis worldwide, there are increasing reports of drug resistance and cases of relapse after long term treatment with the existing drugs of choice. This study therefore aims at identifying possible natural inhibitors of Brucella melitensis Methionyl-tRNA synthetase through an in-silico approach. Methods Using PyRx 0.8 virtual screening software, the target was docked against a library of natural compounds obtained from edible African plants. The compound, 2-({3-[(3,5-dichlorobenzyl) amino] propyl} amino) quinolin-4(1H)-one (OOU) which is a co-crystallized ligand with the target was used as the reference compound. Screening of the molecular descriptors of the compounds for bioavailability, pharmacokinetic properties, and bioactivity was performed using the SWISSADME, pkCSM, and Molinspiration web servers respectively. The Fpocket and PLIP webservers were used to perform the analyses of the binding pockets and the protein ligand interactions. Analysis of the time-resolved trajectories of the Apo and Holo forms of the target was performed using the Galaxy and MDWeb servers. Results The lead compounds, Strophanthidin and Isopteropodin are present in Corchorus olitorius and Uncaria tomentosa (Cat’s-claw) plants respectively. Isopteropodin had a binding affinity score of -8.9 kcal / ml with the target and had 17 anti-correlating residues in Pocket 1 after molecular dynamics simulation. The complex formed by Isopteropodin and the target had a total RMSD of 4.408 and a total RMSF of 9.8067. However, Strophanthidin formed 3 hydrogen bonds with the target at ILE21, GLY262 and LEU294, and induced a total RMSF of 5.4541 at Pocket 1. Conclusion Overall, Isopteropodin and Strophanthidin were found to be better drug candidates than OOU and they showed potentials to inhibit the Brucella melitensis Methionyl-tRNA synthetase at Pocket 1, hence abilities to treat brucellosis. In-vivo and in-vitro investigations are needed to further evaluate the efficacy and toxicity of the lead compounds. The cure for brucellosis involves a long course of treatment with a combination of antibiotics. However, some of the drugs are not recommended for very young children and pregnant women. Moreover, cases of relapse and resistance to these drugs are reported. With the Brucella Methionyl-tRNA synthetase as a target, molecular docking and virtual screening was used to identify possible drug candidates from a library of 1524 compounds obtained from edible African plants. Two lead compounds, Strophanthidin and Isopteropodin usually present in Corchorus olitorius and Uncaria tomentosa (Cat’s claw) plants showed potentials to inhibit the Brucella melitensis Methionyl-tRNA synthetase. Their bioactivities were also confirmed in their molecular dynamic simulation with the target protein. Consequently, both compounds have potentials for safety and efficacy in the treatment of brucellosis.
Collapse
Affiliation(s)
| | - Akwoba Joseph Ogugua
- Department of Veterinary Public Health and Preventive Medicine, University of Nigeria, Nsukka, Nigeria
- * E-mail:
| | - Gordon Ibeanu
- Department of Pharmaceutical Science, North Carolina Central University, Durham, North Carolina, United States of America
| | - Doofan Bur
- Department of Medical Biotechnology, National Biotechnology Development Agency, Abuja, Nigeria
| | - Mercy Titilayo Asala
- Department of Medical Biotechnology, National Biotechnology Development Agency, Abuja, Nigeria
| | | | | | - Hamzah Bundu Usman
- Department of Plant Science and Biotechnology, Federal University Gusau, Gusau, Nigeria
| |
Collapse
|
2
|
Mercaldi GF, Andrade MDO, Zanella JDL, Cordeiro AT, Benedetti CE. Molecular basis for diaryldiamine selectivity and competition with tRNA in a type 2 methionyl-tRNA synthetase from a Gram-negative bacterium. J Biol Chem 2021; 296:100658. [PMID: 33857480 PMCID: PMC8165550 DOI: 10.1016/j.jbc.2021.100658] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Revised: 04/06/2021] [Accepted: 04/09/2021] [Indexed: 12/20/2022] Open
Abstract
Gram-negative bacteria are responsible for a variety of human, animal, and plant diseases. The spread of multidrug-resistant Gram-negative bacteria poses a challenge to disease control and highlights the need for novel antimicrobials. Owing to their critical role in protein synthesis, aminoacyl-tRNA synthetases, including the methionyl-tRNA synthetases MetRS1 and MetRS2, are attractive drug targets. MetRS1 has long been exploited as a drug target in Gram-positive bacteria and protozoan parasites. However, MetRS1 inhibitors have limited action upon Gram-negative pathogens or on Gram-positive bacteria that produce MetRS2 enzymes. The underlying mechanism by which MetRS2 enzymes are insensitive to MetRS1 inhibitors is presently unknown. Herein, we report the first structures of MetRS2 from a multidrug-resistant Gram-negative bacterium in its ligand-free state and bound to its substrate or MetRS1 inhibitors. The structures reveal the binding mode of two diaryldiamine MetRS1 inhibitors that occupy the amino acid-binding site and a surrounding auxiliary pocket implicated in tRNA acceptor arm binding. The structural features associated with amino acid polymorphisms found in the methionine and auxiliary pockets reveal the molecular basis for diaryldiamine binding and selectivity between MetRS1 and MetRS2 enzymes. Moreover, we show that mutations in key polymorphic residues in the methionine and auxiliary pockets not only altered inhibitor binding affinity but also significantly reduced enzyme function. Our findings thus reinforce the tRNA acceptor arm binding site as a druggable pocket in class I aminoacyl-tRNA synthetases and provide a structural basis for optimization of MetRS2 inhibitors for the development of new antimicrobials against Gram-negative pathogens.
Collapse
Affiliation(s)
- Gustavo Fernando Mercaldi
- Brazilian Biosciences National Laboratory (LNBio), Brazilian Centre for Research in Energy and Materials (CNPEM), Campinas, SP, Brazil.
| | - Maxuel de Oliveira Andrade
- Brazilian Biosciences National Laboratory (LNBio), Brazilian Centre for Research in Energy and Materials (CNPEM), Campinas, SP, Brazil
| | - Jackeline de Lima Zanella
- Brazilian Biosciences National Laboratory (LNBio), Brazilian Centre for Research in Energy and Materials (CNPEM), Campinas, SP, Brazil
| | - Artur Torres Cordeiro
- Brazilian Biosciences National Laboratory (LNBio), Brazilian Centre for Research in Energy and Materials (CNPEM), Campinas, SP, Brazil
| | - Celso Eduardo Benedetti
- Brazilian Biosciences National Laboratory (LNBio), Brazilian Centre for Research in Energy and Materials (CNPEM), Campinas, SP, Brazil.
| |
Collapse
|
3
|
Mei X, Qi D, Zhang T, Zhao Y, Jin L, Hou J, Wang J, Lin Y, Xue Y, Zhu P, Liu Z, Huang L, Nie J, Si W, Ma J, Ye J, Finnell RH, Saiyin H, Wang H, Zhao J, Zhao S, Xu W. Inhibiting MARSs reduces hyperhomocysteinemia-associated neural tube and congenital heart defects. EMBO Mol Med 2020; 12:e9469. [PMID: 32003121 PMCID: PMC7059139 DOI: 10.15252/emmm.201809469] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2018] [Revised: 12/16/2019] [Accepted: 12/19/2019] [Indexed: 02/05/2023] Open
Abstract
Hyperhomocysteinemia is a common metabolic disorder that imposes major adverse health consequences. Reducing homocysteine levels, however, is not always effective against hyperhomocysteinemia-associated pathologies. Herein, we report the potential roles of methionyl-tRNA synthetase (MARS)-generated homocysteine signals in neural tube defects (NTDs) and congenital heart defects (CHDs). Increased copy numbers of MARS and/or MARS2 were detected in NTD and CHD patients. MARSs sense homocysteine and transmit its signal by inducing protein lysine (N)-homocysteinylation. Here, we identified hundreds of novel N-homocysteinylated proteins. N-homocysteinylation of superoxide dismutases (SOD1/2) provided new mechanistic insights for homocysteine-induced oxidative stress, apoptosis and Wnt signalling deregulation. Elevated MARS expression in developing and proliferating cells sensitizes them to the effects of homocysteine. Targeting MARSs using the homocysteine analogue acetyl homocysteine thioether (AHT) reversed MARS efficacy. AHT lowered NTD and CHD onsets in retinoic acid-induced and hyperhomocysteinemia-induced animal models without affecting homocysteine levels. We provide genetic and biochemical evidence to show that MARSs are previously overlooked genetic determinants and key pathological factors of hyperhomocysteinemia, and suggest that MARS inhibition represents an important medicinal approach for controlling hyperhomocysteinemia-associated diseases.
Collapse
|
4
|
Lomeli BK, Galbraith H, Schettler J, Saviolakis GA, El-Amin W, Osborn B, Ravel J, Hazleton K, Lozupone CA, Evans RJ, Bell SJ, Ochsner UA, Jarvis TC, Baqar S, Janjic N. Multiple-Ascending-Dose Phase 1 Clinical Study of the Safety, Tolerability, and Pharmacokinetics of CRS3123, a Narrow-Spectrum Agent with Minimal Disruption of Normal Gut Microbiota. Antimicrob Agents Chemother 2019; 64:e01395-19. [PMID: 31685472 PMCID: PMC7187627 DOI: 10.1128/aac.01395-19] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2019] [Accepted: 10/09/2019] [Indexed: 12/26/2022] Open
Abstract
CRS3123 is a novel small molecule that potently inhibits methionyl-tRNA synthetase of Clostridioides difficile, inhibiting C. difficile toxin production and spore formation. CRS3123 has been evaluated in a multiple-ascending-dose placebo-controlled phase 1 trial. Thirty healthy subjects, ages 18 to 45 years, were randomized into three cohorts of 10 subjects each, receiving either 200, 400, or 600 mg of CRS3123 (8 subjects per cohort) or placebo (2 subjects per cohort) by oral administration twice daily for 10 days. CRS3123 was generally safe and well tolerated, with no serious adverse events (SAEs) or severe treatment-emergent adverse events (TEAEs) reported. All subjects completed their assigned treatment and follow-up visits, and there were no trends in systemic, vital sign, or laboratory TEAEs. There were no QTcF interval changes or any clinically significant changes in other electrocardiogram (ECG) intervals or morphology. CRS3123 showed limited but detectable systemic uptake; although absorption increased with increasing dose, the increase was less than dose proportional. Importantly, the bulk of the oral dose was not absorbed, and fecal concentrations were substantially above the MIC90 value of 1 μg/ml at all dosages tested. Subjects receiving either of the two lower doses of CRS3123 exhibited minimal disruption of normal gut microbiota after 10 days of twice-daily dosing. CRS3123 was inactive against important commensal anaerobes, including Bacteroides, bifidobacteria, and commensal clostridia. Microbiome data showed favorable differentiation compared to other CDI therapeutics. These results support further development of CRS3123 as an oral agent for the treatment of CDI. (This study has been registered at Clinicaltrials.gov under identifier NCT02106338.).
Collapse
Affiliation(s)
| | - Hal Galbraith
- Quintiles Phase One Services, Overland Park, Kansas, USA
| | | | | | - Wael El-Amin
- DynPort Vaccine Company LLC, Frederick, Maryland, USA
| | - Blaire Osborn
- Division of Microbiology and Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Jacques Ravel
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, Maryland, USA
- Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Keith Hazleton
- Division of Pediatric Gastroenterology, Hepatology and Nutrition, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Catherine A Lozupone
- Division of Biomedical Informatics and Personalized Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | | | | | | | | | - Shahida Baqar
- Division of Microbiology and Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | | |
Collapse
|
5
|
Buckner FS, Ranade RM, Gillespie JR, Shibata S, Hulverson MA, Zhang Z, Huang W, Choi R, Verlinde CLMJ, Hol WGJ, Ochida A, Akao Y, Choy RKM, Van Voorhis WC, Arnold SLM, Jumani RS, Huston CD, Fan E. Optimization of Methionyl tRNA-Synthetase Inhibitors for Treatment of Cryptosporidium Infection. Antimicrob Agents Chemother 2019; 63:e02061-18. [PMID: 30745384 PMCID: PMC6437504 DOI: 10.1128/aac.02061-18] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Accepted: 02/01/2019] [Indexed: 02/07/2023] Open
Abstract
Cryptosporidiosis is one of the leading causes of moderate to severe diarrhea in children in low-resource settings. The therapeutic options for cryptosporidiosis are limited to one drug, nitazoxanide, which unfortunately has poor activity in the most needy populations of malnourished children and HIV-infected persons. We describe here the discovery and early optimization of a class of imidazopyridine-containing compounds with potential for treating Cryptosporidium infections. The compounds target the Cryptosporidium methionyl-tRNA synthetase (MetRS), an enzyme that is essential for protein synthesis. The most potent compounds inhibited the enzyme with Ki values in the low picomolar range. Cryptosporidium cells in culture were potently inhibited with 50% effective concentrations as low as 7 nM and >1,000-fold selectivity over mammalian cells. A parasite persistence assay indicates that the compounds act by a parasiticidal mechanism. Several compounds were demonstrated to control infection in two murine models of cryptosporidiosis without evidence of toxicity. Pharmacological and physicochemical characteristics of compounds were investigated to determine properties that were associated with higher efficacy. The results indicate that MetRS inhibitors are excellent candidates for development for anticryptosporidiosis therapy.
Collapse
Affiliation(s)
| | - Ranae M Ranade
- Department of Medicine, University of Washington, Seattle, Washington, USA
| | - J Robert Gillespie
- Department of Medicine, University of Washington, Seattle, Washington, USA
| | - Sayaka Shibata
- Department of Biochemistry, University of Washington, Seattle, Washington, USA
| | | | - Zhongsheng Zhang
- Department of Biochemistry, University of Washington, Seattle, Washington, USA
| | - Wenlin Huang
- Department of Biochemistry, University of Washington, Seattle, Washington, USA
| | - Ryan Choi
- Department of Medicine, University of Washington, Seattle, Washington, USA
| | | | - Wim G J Hol
- Department of Biochemistry, University of Washington, Seattle, Washington, USA
| | | | | | - Robert K M Choy
- Drug Development Program, PATH, San Francisco, California, USA
| | | | - Sam L M Arnold
- Department of Medicine, University of Washington, Seattle, Washington, USA
| | - Rajiv S Jumani
- Department of Medicine, University of Vermont, Burlington, Vermont, USA
| | | | - Erkang Fan
- Department of Biochemistry, University of Washington, Seattle, Washington, USA
| |
Collapse
|
6
|
Huang W, Zhang Z, Ranade RM, Gillespie JR, Barros-Álvarez X, Creason SA, Shibata S, Verlinde CLMJ, Hol WGJ, Buckner FS, Fan E. Optimization of a binding fragment targeting the "enlarged methionine pocket" leads to potent Trypanosoma brucei methionyl-tRNA synthetase inhibitors. Bioorg Med Chem Lett 2017; 27:2702-2707. [PMID: 28465105 DOI: 10.1016/j.bmcl.2017.04.048] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Accepted: 04/14/2017] [Indexed: 11/18/2022]
Abstract
Potent inhibitors of Trypanosoma brucei methionyl-tRNA synthetase were previously designed using a structure-guided approach. Compounds 1 and 2 were the most active compounds in the cyclic and linear linker series, respectively. To further improve cellular potency, SAR investigation of a binding fragment targeting the "enlarged methionine pocket" (EMP) was performed. The optimization led to the identification of a 6,8-dichloro-tetrahydroquinoline ring as a favorable fragment to bind the EMP. Replacement of 3,5-dichloro-benzyl group (the EMP binding fragment) of inhibitor 2 using this tetrahydroquinoline fragment resulted in compound 13, that exhibited an EC50 of 4nM.
Collapse
Affiliation(s)
- Wenlin Huang
- Department of Biochemistry, University of Washington, Seattle, WA 98195, United States
| | - Zhongsheng Zhang
- Department of Biochemistry, University of Washington, Seattle, WA 98195, United States
| | - Ranae M Ranade
- Department of Medicine, Division of Allergy and Infectious Diseases, and the Center for Emerging and Re-emerging Infectious Diseases (CERID), University of Washington, Seattle, WA 98109, United States
| | - J Robert Gillespie
- Department of Medicine, Division of Allergy and Infectious Diseases, and the Center for Emerging and Re-emerging Infectious Diseases (CERID), University of Washington, Seattle, WA 98109, United States
| | - Ximena Barros-Álvarez
- Department of Biochemistry, University of Washington, Seattle, WA 98195, United States; Laboratorio de Enzimología de Parásitos, Facultad de Ciencias, Universidad de los Andes, Mérida, Venezuela
| | - Sharon A Creason
- Department of Medicine, Division of Allergy and Infectious Diseases, and the Center for Emerging and Re-emerging Infectious Diseases (CERID), University of Washington, Seattle, WA 98109, United States
| | - Sayaka Shibata
- Department of Biochemistry, University of Washington, Seattle, WA 98195, United States
| | | | - Wim G J Hol
- Department of Biochemistry, University of Washington, Seattle, WA 98195, United States
| | - Frederick S Buckner
- Department of Medicine, Division of Allergy and Infectious Diseases, and the Center for Emerging and Re-emerging Infectious Diseases (CERID), University of Washington, Seattle, WA 98109, United States.
| | - Erkang Fan
- Department of Biochemistry, University of Washington, Seattle, WA 98195, United States.
| |
Collapse
|
7
|
Ojo KK, Ranade RM, Zhang Z, Dranow DM, Myers JB, Choi R, Nakazawa Hewitt S, Edwards TE, Davies DR, Lorimer D, Boyle SM, Barrett LK, Buckner FS, Fan E, Van Voorhis WC. Brucella melitensis Methionyl-tRNA-Synthetase (MetRS), a Potential Drug Target for Brucellosis. PLoS One 2016; 11:e0160350. [PMID: 27500735 PMCID: PMC4976878 DOI: 10.1371/journal.pone.0160350] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2016] [Accepted: 07/18/2016] [Indexed: 12/22/2022] Open
Abstract
We investigated Brucella melitensis methionyl-tRNA-synthetase (BmMetRS) with molecular, structural and phenotypic methods to learn if BmMetRS is a promising target for brucellosis drug development. Recombinant BmMetRS was expressed, purified from wild type Brucella melitensis biovar Abortus 2308 strain ATCC/CRP #DD-156 and screened by a thermal melt assay against a focused library of one hundred previously classified methionyl-tRNA-synthetase inhibitors of the blood stage form of Trypanosoma brucei. Three compounds showed appreciable shift of denaturation temperature and were selected for further studies on inhibition of the recombinant enzyme activity and cell viability against wild type B. melitensis strain 16M. BmMetRS protein complexed with these three inhibitors resolved into three-dimensional crystal structures and was analyzed. All three selected methionyl-tRNA-synthetase compounds inhibit recombinant BmMetRS enzymatic functions in an aminoacylation assay at varying concentrations. Furthermore, growth inhibition of B. melitensis strain 16M by the compounds was shown. Inhibitor-BmMetRS crystal structure models were used to illustrate the molecular basis of the enzyme inhibition. Our current data suggests that BmMetRS is a promising target for brucellosis drug development. However, further studies are needed to optimize lead compound potency, efficacy and safety as well as determine the pharmacokinetics, optimal dosage, and duration for effective treatment.
Collapse
Affiliation(s)
- Kayode K. Ojo
- Center for Emerging and Re-emerging Infectious Diseases (CERID), Department of Medicine, Division of Allergy and Infectious Diseases, University of Washington, Seattle, Washington, United States of America
| | - Ranae M. Ranade
- Center for Emerging and Re-emerging Infectious Diseases (CERID), Department of Medicine, Division of Allergy and Infectious Diseases, University of Washington, Seattle, Washington, United States of America
| | - Zhongsheng Zhang
- Department of Biochemistry, University of Washington, Seattle, Washington, United States of America
| | - David M. Dranow
- Beryllium, Bainbridge Island, Washington, United States of America
| | - Janette B. Myers
- Center for Emerging and Re-emerging Infectious Diseases (CERID), Department of Medicine, Division of Allergy and Infectious Diseases, University of Washington, Seattle, Washington, United States of America
| | - Ryan Choi
- Center for Emerging and Re-emerging Infectious Diseases (CERID), Department of Medicine, Division of Allergy and Infectious Diseases, University of Washington, Seattle, Washington, United States of America
| | - Steve Nakazawa Hewitt
- Center for Emerging and Re-emerging Infectious Diseases (CERID), Department of Medicine, Division of Allergy and Infectious Diseases, University of Washington, Seattle, Washington, United States of America
| | | | | | - Donald Lorimer
- Beryllium, Bainbridge Island, Washington, United States of America
| | - Stephen M. Boyle
- Center for Molecular Medicine and Infectious Diseases, Department of Biomedical Sciences and Pathobiology, Virginia Polytechnic Institute and State University, Blacksburg, Virginia, United States of America
| | - Lynn K. Barrett
- Center for Emerging and Re-emerging Infectious Diseases (CERID), Department of Medicine, Division of Allergy and Infectious Diseases, University of Washington, Seattle, Washington, United States of America
| | - Frederick S. Buckner
- Center for Emerging and Re-emerging Infectious Diseases (CERID), Department of Medicine, Division of Allergy and Infectious Diseases, University of Washington, Seattle, Washington, United States of America
| | - Erkang Fan
- Department of Biochemistry, University of Washington, Seattle, Washington, United States of America
| | - Wesley C. Van Voorhis
- Center for Emerging and Re-emerging Infectious Diseases (CERID), Department of Medicine, Division of Allergy and Infectious Diseases, University of Washington, Seattle, Washington, United States of America
| |
Collapse
|
8
|
Green LS, Bullard JM, Ribble W, Dean F, Ayers DF, Ochsner UA, Janjic N, Jarvis TC. Inhibition of methionyl-tRNA synthetase by REP8839 and effects of resistance mutations on enzyme activity. Antimicrob Agents Chemother 2009; 53:86-94. [PMID: 19015366 PMCID: PMC2612134 DOI: 10.1128/aac.00275-08] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2008] [Revised: 06/09/2008] [Accepted: 10/22/2008] [Indexed: 11/20/2022] Open
Abstract
REP8839 is a selective inhibitor of methionyl-tRNA synthetase (MetRS) with antibacterial activity against a variety of gram-positive organisms. We determined REP8839 potency against Staphylococcus aureus MetRS and assessed its selectivity for bacterial versus human orthologs of MetRS. The inhibition constant (K(i)) of REP8839 was 10 pM for Staphylococcus aureus MetRS. Inhibition of MetRS by REP8839 was competitive with methionine and uncompetitive with ATP. Thus, high physiological ATP levels would actually facilitate optimal binding of the inhibitor. While many gram-positive bacteria, such as Staphylococcus aureus, express exclusively the MetRS1 subtype, many gram-negative bacteria express an alternative homolog called MetRS2. Some gram-positive bacteria, such as Streptococcus pneumoniae and Bacillus anthracis, express both MetRS1 and MetRS2. MetRS2 orthologs were considerably less susceptible to REP8839 inhibition. REP8839 inhibition of human mitochondrial MetRS was 1,000-fold weaker than inhibition of Staphylococcus aureus MetRS; inhibition of human cytoplasmic MetRS was not detectable, corresponding to >1,000,000-fold selectivity for the bacterial target relative to its cytoplasmic counterpart. Mutations in MetRS that confer reduced susceptibility to REP8839 were examined. The mutant MetRS enzymes generally exhibited substantially impaired catalytic activity, particularly in aminoacylation turnover rates. REP8839 K(i) values ranged from 4- to 190,000-fold higher for the mutant enzymes than for wild-type MetRS. These observations provide a potential mechanistic explanation for the reduced growth fitness observed with MetRS mutant strains relative to that with wild-type Staphylococcus aureus.
Collapse
|
9
|
Chopra I. Translational medicine for antibacterial drug development - A Marcus Evans conference: overcoming the challenge of proof of concept. IDrugs 2008; 11:236-238. [PMID: 18379951] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Affiliation(s)
- Ian Chopra
- University of Leeds, Antimicrobial Research Centre and Institute of Molecular and Cellular Biology, Leeds, LS2 9JT, UK.
| |
Collapse
|
10
|
Kedar GC, Brown-Driver V, Reyes DR, Hilgers MT, Stidham MA, Shaw KJ, Finn J, Haselbeck RJ. Evaluation of the metS and murB loci for antibiotic discovery using targeted antisense RNA expression analysis in Bacillus anthracis. Antimicrob Agents Chemother 2007; 51:1708-18. [PMID: 17339372 PMCID: PMC1855544 DOI: 10.1128/aac.01180-06] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
The biowarfare-relevant bacterial pathogen Bacillus anthracis contains two paralogs each of the metS and murB genes, which encode the important antibiotic target functions methionyl-tRNA synthetase and UDP-N-acetylenolpyruvoylglucosamine reductase, respectively. Empirical screens were conducted to detect and characterize gene fragments of each of these four genes that could cause growth reduction of B. anthracis when inducibly expressed from a plasmid-borne promoter. Numerous such gene fragments that were overwhelmingly in the antisense orientation were identified for the metS1 and murB2 alleles, while no such orientation bias was seen for the metS2 and murB1 alleles. Gene replacement mutagenesis was used to confirm the essentiality of the metS1 and murB2 alleles, and the nonessentiality of the metS2 and murB1 alleles, for vegetative growth. Induced transcription of RNA from metS1 and murB2 antisense-oriented gene fragments resulted in specific reduction of mRNA of their cognate genes. Attenuation of MetS1 enzyme expression hypersensitized B. anthracis cells to a MetS-specific antimicrobial compound but not to other antibiotics that affect cell wall assembly, fatty acid biosynthesis, protein translation, or DNA replication. Antisense-dependent reduction of MurB2 enzyme expression caused hypersensitivity to beta-lactam antibiotics, a synergistic response that has also been noted for the MurA-specific antibiotic fosfomycin. These experiments form the basis of mode-of-action detection assays that can be used in the discovery of novel MetS- or MurB-specific antibiotic drugs that are effective against B. anthracis or other gram-positive bacterial pathogens.
Collapse
Affiliation(s)
- G C Kedar
- Trius Therapeutics Inc, San Diego, CA 92121, USA
| | | | | | | | | | | | | | | |
Collapse
|
11
|
Bharatham N, Bharatham K, Lee KW. Pharmacophore identification and virtual screening for methionyl-tRNA synthetase inhibitors. J Mol Graph Model 2007; 25:813-23. [PMID: 16996282 DOI: 10.1016/j.jmgm.2006.08.002] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2006] [Revised: 08/03/2006] [Accepted: 08/03/2006] [Indexed: 11/16/2022]
Abstract
Aminoacyl-tRNA synthetases (aaRSs) are essential enzymes involved in protein biosynthesis in all living organisms and are an unexploited antibacterial targets, as many strains of bacteria have become resistant to all established classes of antibiotics. Therefore, the main aim of this study is to discover new lead molecules which would be useful as anti-bacterial compounds. Pharmacophore models were developed by using CATALYST HypoGen with a training set of 29 diverse methionyl-tRNA synthetase (MetRS) inhibitors. The best quantitative pharmacophore hypothesis (Hypo1) obtained a correlation coefficient of 0.975, root mean square deviation (RMSD) of 0.55 and cost difference (null cost-total cost) of 70.32. This Hypo1 was validated by two methods, first by using 104 test set molecules which resulted a correlation of 0.926 between HypoGen estimated activities versus experimental activities and secondly by Cat-Scramble validation method. This validated pharmacophore model was further used for screening databases for discovery of new MetRS inhibitors. The new lead compounds were further analyzed for drug-like properties. Homology modeled structure of Staphylococcus aureus MetRS was built and molecular docking studies were performed with many inhibitors using the newly built protein structure. Finally, it was found that the new leads exhibited good estimated inhibitory activity, calculated binding properties similar to experimentally proven compounds and also favorable drug-like properties.
Collapse
Affiliation(s)
- Nagakumar Bharatham
- Department of Biochemistry, Division of Applied Life Science, Environmental Biotechnology National Core Research Center, Gyeongsang National University, Jinju 660-701, Republic of Korea
| | | | | |
Collapse
|
12
|
Kim SY, Yoon EJ, Choi EC, Kim S, Kang T, Samrin F, Puri S, Lee J. Design and synthesis of quinolinones as methionyl-tRNA synthetase inhibitors. Bioorg Med Chem 2006; 14:7154-9. [PMID: 16854585 DOI: 10.1016/j.bmc.2006.06.062] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2006] [Revised: 06/26/2006] [Accepted: 06/28/2006] [Indexed: 10/24/2022]
Abstract
Five new structural analogues of substituted-1H-quinolinones (19, 20, 23, 24, and 26) have been synthesized and evaluated for Staphylococcus aureus methionyl-tRNA synthetase enzyme inhibitory activity. These compounds were also tested against pathogens of six S. aureus, two Enterococcus faecalis, and one Enterococcus faecium. Among all the synthesized quinolinones, compound 20 displayed significant inhibitory activities in the strains of E. faecalis and E. faecium.
Collapse
|
13
|
Kim SY, Lee YS, Kang T, Kim S, Lee J. Pharmacophore-based virtual screening: The discovery of novel methionyl-tRNA synthetase inhibitors. Bioorg Med Chem Lett 2006; 16:4898-907. [PMID: 16824759 DOI: 10.1016/j.bmcl.2006.06.057] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2006] [Revised: 06/01/2006] [Accepted: 06/16/2006] [Indexed: 10/24/2022]
Abstract
We have performed virtual screening of a chemical database of 508,143 commercially available chemicals to search for new methionyl-tRNA synthetase (MetRS) inhibitors. In this study, potent lead compounds with a novel skeleton, including compound 27 with IC50 = 237 nM, were successfully identified as Escherichia coli MetRS inhibitors.
Collapse
Affiliation(s)
- Su Yeon Kim
- Laboratory of Medicinal Chemistry, Research Institute of Pharmaceutical Sciences, College of Pharmacy, Seoul National University, Shinlim-Dong, Kwanak-Ku, Seoul 151-742, Republic of Korea
| | | | | | | | | |
Collapse
|
14
|
Vaughan MD, Sampson PB, Daub E, Honek JF. Investigation of bioisosteric effects on the interaction of substrates/ inhibitors with the methionyl-tRNA synthetase from Escherichia coli. Med Chem 2006; 1:227-37. [PMID: 16787318 DOI: 10.2174/1573406053765477] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Aminoacyl-tRNA synthetases catalyze the stepwise coupling of specific amino acid substrates to their cognate tRNAs. The first intermediate formed in this process is the aminoacyl-adenylate, which then subsequently reacts with the 3'-terminus of the cognate tRNA to transfer the amino acid to the tRNA. This overall reaction is critical for protein biosynthesis and is quintessential to the viability of all organisms. Therefore, the selective inhibition of bacterial amino acid-tRNA synthetases is the focus of intense current interest for the development of novel antibacterial agents. In order to elucidate some of the critical factors involved in recognition and binding of potential inhibitors to these bacterial systems, the current report has focused on the methionyl-tRNA synthetase from Escherichia coli. This enzyme has been studied with two sets of bioisosteric replacements in the methionine and methionyl-adenylate structures. Replacements of the carboxyl group of methionine with the phosphinic and phosphonic acid moieties were used to probe the effects of including potential transition state analogs on enzyme inhibition. The contributions of the aminoacyl-adenylate structure and the effect that fluorination has on inhibitory activity were investigated utilizing 5'-O-[(L-methionyl)-sulfamoyl]adenosine and 5'-O-[(S-trifluoromethyl-L-homocysteinyl)-sulfamoyl]adenosine. The K(i) values for these compounds were determined to be 0.4 mM, 1.2 mM, 0.25 nM and 2.4 nM respectively. A discussion of this data in relation to structural information provided by the recent determination of the three-dimensional structures of the E. coli enzyme with several of these compounds is presented.
Collapse
Affiliation(s)
- M D Vaughan
- Department of Chemistry, University of Waterloo, 200 University Avenue, Waterloo, ON, N2L 3G1, Canada
| | | | | | | |
Collapse
|
15
|
Ochsner UA, Young CL, Stone KC, Dean FB, Janjic N, Critchley IA. Mode of action and biochemical characterization of REP8839, a novel inhibitor of methionyl-tRNA synthetase. Antimicrob Agents Chemother 2006; 49:4253-62. [PMID: 16189106 PMCID: PMC1251548 DOI: 10.1128/aac.49.10.4253-4262.2005] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Aminoacyl-tRNA synthetases have attracted interest as essential and novel targets involved in bacterial protein synthesis. REP8839 is a potent inhibitor of MetS, the methionyl-tRNA synthetase in Staphylococcus aureus, including methicillin-resistant S. aureus (MRSA), and in Streptococcus pyogenes. The biochemical activity of REP8839 was shown by specific inhibition of purified S. aureus MetS (50% inhibitory concentration, <1.9 nM). Target specificity was confirmed by overexpression of the metS gene in S. aureus, resulting in an eightfold increase in the MIC for REP8839. Macromolecular synthesis assays in the presence of REP8839 demonstrated a dose-dependent inhibition of protein synthesis and RNA synthesis in S. pneumoniae R6, but only protein synthesis was affected in an isogenic rel mutant deficient in the stringent response. Strains with reduced susceptibility to REP8839 were generated by selection of strains with spontaneous mutations and through serial passages. Point mutations within the metS gene were mapped, leading to a total of 23 different amino acid substitutions within MetS that were located around the modeled active site. The most frequent MetS mutations were I57N, leading to a shift in the MIC from 0.06 microg/ml to 4 microg/ml, and G54S, resulting in a MIC of 32 microg/ml that was associated with a reduced growth rate. The mutation prevention concentration was 32 microg/ml in four S. aureus strains (methicillin-sensitive S. aureus and MRSA), which is well below the drug concentration of 2% (20,000 microg/ml) in a topical formulation. In conclusion, we demonstrate by biochemical, physiologic, and genetic mode-of-action studies that REP8839 exerts its antibacterial activity through specific inhibition of MetS, a novel target.
Collapse
|
16
|
Kim SE, Kim SY, Kim S, Kang T, Lee J. Deoxyribosyl analogues of methionyl and isoleucyl sulfamate adenylates as inhibitors of methionyl-tRNA and isoleucyl-tRNA synthetases. Bioorg Med Chem Lett 2005; 15:3389-93. [PMID: 15951176 DOI: 10.1016/j.bmcl.2005.05.035] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2005] [Revised: 05/06/2005] [Accepted: 05/09/2005] [Indexed: 10/25/2022]
Abstract
2'-Deoxy, 3'-deoxy, and 2',3'-dideoxyribosyl surrogates of isoleucyl and methionyl sulfamate adenylates have been investigated to identify the pharmacophoric importance of the ribose group for the inhibition of Escherichia coli methionyl-tRNA (MRS) and isoleucyl-tRNA (IRS) synthetases. Molecular modeling of 2',3'-dideoxyribosyl Met-NHSO2-AMP (9) with the crystal structure of E. coli MRS revealed that the lack of the two hydroxyl groups on ribose was compensated by the formation of an extra hydrogen bond between the ring oxygen and His24, resulting in a small activity reduction.
Collapse
Affiliation(s)
- Sung Eun Kim
- Laboratory of Medicinal Chemistry, Research Institute of Pharmaceutical Sciences, College of Pharmacy, Seoul National University, Shinlim-Dong, Kwanak-Ku, Seoul 151-742, Republic of Korea
| | | | | | | | | |
Collapse
|
17
|
Critchley IA, Young CL, Stone KC, Ochsner UA, Guiles J, Tarasow T, Janjic N. Antibacterial activity of REP8839, a new antibiotic for topical use. Antimicrob Agents Chemother 2005; 49:4247-52. [PMID: 16189105 PMCID: PMC1251549 DOI: 10.1128/aac.49.10.4247-4252.2005] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2005] [Revised: 06/14/2005] [Accepted: 07/07/2005] [Indexed: 11/20/2022] Open
Abstract
REP8839 is a novel methionyl-tRNA synthetase (MetS) inhibitor with potent antibacterial activity against clinical isolates of Staphylococcus aureus, Streptococcus pyogenes, and other clinically important gram-positive bacteria but little activity against gram-negative bacteria. All isolates of S. aureus, including strains resistant to methicillin, mupirocin, vancomycin, and linezolid were susceptible to REP8839 at concentrations of < or =0.5 microg/ml. REP8839 was also active against Staphylococcus epidermidis, including multiply resistant strains (MIC, < or =0.25 microg/ml). All S. pyogenes isolates were susceptible to REP8839 at concentrations of < or =0.25 microg/ml, suggesting that MetS2, a second enzyme previously identified in Streptococcus pneumoniae, was not present in this organism. REP8839 was highly bound to the protein of human serum, and activity was not greatly influenced by inoculum size but was affected by pH, exhibiting optimal antibacterial activity in a neutral medium rather than a weak acidic medium. Like mupirocin, REP8839 exhibited bacteriostatic activity against key pathogens. The emergence of mupirocin resistance in S. aureus highlights the need for a new topical antibiotic with the ability to inhibit high-level mupirocin-resistant strains and other emerging phenotypes, such as vancomycin-resistant and community-acquired methicillin-resistant isolates.
Collapse
|
18
|
Jarvest RL, Armstrong SA, Berge JM, Brown P, Elder JS, Brown MJ, Copley RCB, Forrest AK, Hamprecht DW, O'Hanlon PJ, Mitchell DJ, Rittenhouse S, Witty DR. Definition of the heterocyclic pharmacophore of bacterial methionyl tRNA synthetase inhibitors: potent antibacterially active non-quinolone analogues. Bioorg Med Chem Lett 2005; 14:3937-41. [PMID: 15225702 DOI: 10.1016/j.bmcl.2004.05.070] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2004] [Revised: 05/24/2004] [Accepted: 05/24/2004] [Indexed: 11/21/2022]
Abstract
Potent inhibitors of bacterial methionyl tRNA synthetase (MRS) have previously been reported. Through SAR of the quinolone moiety, the right hand side pharmacophore for MRS inhibition has now been defined as an NH-C-NH functionality in the context of a bicyclic heteroaromatic system. Potent antibacterial fused-pyrimidone and fused-imidazole analogues have been obtained and enantioselective activity demonstrated. Compound 46 demonstrated very good antibacterial activity against panels of antibiotic-resistant staphylococci and enterococci.
Collapse
Affiliation(s)
- Richard L Jarvest
- GlaxoSmithKline, New Frontiers Science Park, Third Avenue, Harlow, Essex CM19 5AW, UK.
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
19
|
Tandon M, Coffen DL, Gallant P, Keith D, Ashwell MA. Potent and selective inhibitors of bacterial methionyl tRNA synthetase derived from an oxazolone-dipeptide scaffold. Bioorg Med Chem Lett 2004; 14:1909-11. [PMID: 15050625 DOI: 10.1016/j.bmcl.2004.01.094] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2003] [Revised: 01/27/2004] [Accepted: 01/28/2004] [Indexed: 10/26/2022]
Abstract
The preparation and structure-activity relationships (SARs) of potent and selective small molecule inhibitors of bacterial methionyl-tRNA synthetase (MetRS) derived from an oxazolone-dipeptide scaffold are described. Examples combine Staphylococcus aureus MetRS (SaMetRS) potency with selectivity over human MetRS. As a result of the SAR expansion compound 14a was identified, as a potent SaMetRS inhibitor (IC(50)=18 nM) having moderate inhibition of MetRS derived from Enterococci faecalis (IC(50)=3.51 microM).
Collapse
Affiliation(s)
- Manish Tandon
- ArQule Inc., 19 Presidential Way, Woburn, MA 01801, USA
| | | | | | | | | |
Collapse
|
20
|
Abstract
The three-dimensional quantitative structure-activity relationships of 57 2-[(aminopropyl)amino]-4(1H)-quinolinone analogues as Staphylococcus aureus methionyl-tRNA synthetase (MetRS) inhibitors with excellent antibacterial profile were investigated and docking studies were performed. The CoMFA analysis provided a model with a q(2) value of 0.579 and an r(2) value of 0.970, in which the good correlation between the MetRS inhibitory activities (IC(50)) and the steric and electrostatic molecular fields around the analogues was examined. Two inhibitors (1 and 17) were docked into the binding pocket of Escherichia coli MetRS imported from the X-ray crystal structure of the MetRS-methionine complex, and the details of their interaction with the amino acids of the active site are discussed.
Collapse
Affiliation(s)
- Su Yeon Kim
- Laboratory of Medicinal Chemistry, Research Institute of Pharmaceutical Sciences, College of Pharmacy, Seoul National University, Shinlim-Dong, Kwanak-Ku, Seoul 151-742, South Korea
| | | |
Collapse
|
21
|
Finn J, Mattia K, Morytko M, Ram S, Yang Y, Wu X, Mak E, Gallant P, Keith D. Discovery of a potent and selective series of pyrazole bacterial methionyl-tRNA synthetase inhibitors. Bioorg Med Chem Lett 2003; 13:2231-4. [PMID: 12798340 DOI: 10.1016/s0960-894x(03)00298-1] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Starting with a micromolar lead identified from high-throughput screening, a series of pyrazoles were discovered with significantly improved potency on bacterial methionyl-tRNA synthetase and selectivity over human methionyl-tRNA synthetase.
Collapse
Affiliation(s)
- John Finn
- Cubist Pharmaceutical Inc., 65 Hayden Ave., 02421, Lexington, MA, USA.
| | | | | | | | | | | | | | | | | |
Collapse
|
22
|
Gentry DR, Ingraham KA, Stanhope MJ, Rittenhouse S, Jarvest RL, O'Hanlon PJ, Brown JR, Holmes DJ. Variable sensitivity to bacterial methionyl-tRNA synthetase inhibitors reveals subpopulations of Streptococcus pneumoniae with two distinct methionyl-tRNA synthetase genes. Antimicrob Agents Chemother 2003; 47:1784-9. [PMID: 12760849 PMCID: PMC155832 DOI: 10.1128/aac.47.6.1784-1789.2003] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
As reported previously (J. R. Jarvest et al., J. Med. Chem. 45:1952-1962, 2002), potent inhibitors (at nanomolar concentrations) of Staphylococcus aureus methionyl-tRNA synthetase (MetS; encoded by metS1) have been derived from a high-throughput screening assay hit. Optimized compounds showed excellent activities against staphylococcal and enterococcal pathogens. We report on the bimodal susceptibilities of S. pneumoniae strains, a significant fraction of which was found to be resistant (MIC, > or =8 mg/liter) to these inhibitors. Using molecular genetic techniques, we have found that the mechanism of resistance is the presence of a second, distantly related MetS enzyme, MetS2, encoded by metS2. We present evidence that the metS2 gene is necessary and sufficient for resistance to MetS inhibitors. PCR analysis for the presence of metS2 among a large sample (n = 315) of S. pneumoniae isolates revealed that it is widespread geographically and chronologically, occurring at a frequency of about 46%. All isolates tested also contained the metS1 gene. Searches of public sequence databases revealed that S. pneumoniae MetS2 was most similar to MetS in Bacillus anthracis, followed by MetS in various non-gram-positive bacterial, archaeal, and eukaryotic species, with streptococcal MetS being considerably less similar. We propose that the presence of metS2 in specific strains of S. pneumoniae is the result of horizontal gene transfer which has been driven by selection for resistance to some unknown class of naturally occurring antibiotics with similarities to recently reported synthetic MetS inhibitors.
Collapse
Affiliation(s)
- Daniel R Gentry
- Department of Microbiology, Microbial, Musculoskeletal, and Proliferative Diseases Center of Excellence for Drug Discovery, GlaxoSmithKline, Collegeville, Pennsylvania 19426, USA.
| | | | | | | | | | | | | | | |
Collapse
|
23
|
Jarvest RL, Berge JM, Brown P, Houge-Frydrych CSV, O'Hanlon PJ, McNair DJ, Pope AJ, Rittenhouse S. Conformational restriction of methionyl tRNA synthetase inhibitors leading to analogues with potent inhibition and excellent gram-positive antibacterial activity. Bioorg Med Chem Lett 2003; 13:1265-8. [PMID: 12657260 DOI: 10.1016/s0960-894x(03)00093-3] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Conformationally restricted analogues of the central linker unit of bacterial methionyl tRNA synthetase (MRS) inhibitors have been prepared. The (1S,2R)-cyclopentylmethyl moiety was identified as the preferred cyclic linker, with significant diastereo- and enantioselectivity of activity. Combination of this linker with an optimal substituted aryl right-hand side has resulted in a compound with exceptionally good antibacterial activity against staphylococci and enterococci, including antibiotic resistant strains.
Collapse
Affiliation(s)
- Richard L Jarvest
- GlaxoSmithKline, New Frontiers Science Park, Third Avenue, Harlow, Essex, UK.
| | | | | | | | | | | | | | | |
Collapse
|
24
|
Affiliation(s)
- Scott D Mills
- AstraZeneca R&D Boston, Infection Discovery, 35 Gatehouse Drive, Waltham, MA 02451, USA.
| |
Collapse
|
25
|
Lee J, Kim SE, Lee JY, Kim SY, Kang SU, Seo SH, Chun MW, Kang T, Choi SY, Kim HO. N-Alkoxysulfamide, N-hydroxysulfamide, and sulfamate analogues of methionyl and isoleucyl adenylates as inhibitors of methionyl-tRNA and isoleucyl-tRNA synthetases. Bioorg Med Chem Lett 2003; 13:1087-92. [PMID: 12643918 DOI: 10.1016/s0960-894x(03)00020-9] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
A series of sulfamate surrogates of methionyl and isoleucyl adenylate have been investigated as MetRS and IleRS inhibitors by modifications of the sulfamate linker and adenine moieties. The discovery of 2-iodo Ile-NHSO(2)-AMP (58) as a potent Escherichia coli IleRS inhibitor revealed that a significant hydrophobic interaction between the 2-substituent of Ile-NHSO(2)-AMP and the adenine binding site of IleRS provided its high potency to the enzyme.
Collapse
Affiliation(s)
- Jeewoo Lee
- Laboratory of Medicinal Chemistry, RIPS, College of Pharmacy, Seoul National University, Seoul 151-742, South Korea
| | | | | | | | | | | | | | | | | | | |
Collapse
|
26
|
Jarvest RL, Berge JM, Brown MJ, Brown P, Elder JS, Forrest AK, Houge-Frydrych CSV, O'Hanlon PJ, McNair DJ, Rittenhouse S, Sheppard RJ. Optimisation of aryl substitution leading to potent methionyl tRNA synthetase inhibitors with excellent gram-positive antibacterial activity. Bioorg Med Chem Lett 2003; 13:665-8. [PMID: 12639554 DOI: 10.1016/s0960-894x(02)01027-2] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Optimisation of the left-hand-side aryl moiety of a file compound screening hit against Staphylococcus aureus methionyl tRNA synthetase led to the identification of a series of potent nanomolar inhibitors. The best compounds showed excellent antibacterial activity against staphylococcal and enterococcal pathogens, including strains resistant to clinical antibiotics.
Collapse
Affiliation(s)
- Richard L Jarvest
- GlaxoSmithKline, New Frontiers Science Park, Third Avenue, Harlow, Essex CM19 5AW, UK.
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
27
|
Jarvest RL, Berge JM, Berry V, Boyd HF, Brown MJ, Elder JS, Forrest AK, Fosberry AP, Gentry DR, Hibbs MJ, Jaworski DD, O'Hanlon PJ, Pope AJ, Rittenhouse S, Sheppard RJ, Slater-Radosti C, Worby A. Nanomolar inhibitors of Staphylococcus aureus methionyl tRNA synthetase with potent antibacterial activity against gram-positive pathogens. J Med Chem 2002; 45:1959-62. [PMID: 11985462 DOI: 10.1021/jm025502x] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Potent nanomolar inhibitors of Staphylococcus aureus methionyl tRNA synthetase have been derived from a file compound high throughput screening hit. Optimized compounds show excellent antibacterial activity against staphylococcal and enterococcal pathogens, including strains resistant to clinical antibiotics. Compound 11 demonstrated in vivo efficacy in an S. aureus rat abscess infection model.
Collapse
|
28
|
Abstract
The increasing need for new antibiotics to overcome rapidly developing resistance mechanisms observed in clinical isolates of Gram-positive and Gram-negative eubacteria has placed critical emphasis on the search for new antibacterial enzyme targets and the structural and mechanistic investigation of such targets. Among these potential targets, the enzymes responsible for integrating the amino acid methionine into proteins, along with its subsequent post-translational modification and repair, have emerged as promising candidates for the development of novel antibiotics. As well, there is increasing evidence for the importance of several of these enzymes in the development of anti-cancer, anti-parasitic, and anti-atherosclerotic drugs. Within the last three years, the crystal structures of all of these enzymes have been determined, which offers an unprecedented source of structural information for inhibitor design. The development of combinatorial chemistry and high throughput screening procedures has quickly provided several potent, specific inhibitors for a number of these enzymes, particularly the peptide deformylase, methionine aminopeptidase, and methionyl-tRNA synthetase enzymes. This review critically analyzes the future potential for inhibition of enzymes in this pathway, allowing for a pragmatic view of the success of inhibitor developments and highlighting areas in which further investigations are warranted.
Collapse
Affiliation(s)
- Mark D Vaughan
- Department of Chemistry, University of Waterloo, Waterloo, Ontario, Canada
| | | | | |
Collapse
|
29
|
Lee J, Kang SU, Kim SY, Kim SE, Job YJ, Kim S. Vanilloid and isovanilloid analogues as inhibitors of methionyl-tRNA and isoleucyl-tRNA synthetases. Bioorg Med Chem Lett 2001; 11:965-8. [PMID: 11327601 DOI: 10.1016/s0960-894x(01)00096-8] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
As aminoacyl adenylate surrogates, a series of methionyl and isoleucyl phenolic analogues containing bioisosteric linkers mimicking ribose have been investigated. Inhibition of synthesized compounds to the aminoacylation reaction by the corresponding Escherichia coli methionyl-tRNA and isoleucyl-tRNA synthetases indicated that 18 was found to be a potent inhibitor of isoleucyl-tRNA synthetase. A molecular modeling study demonstrated that in 18, isovanillate and hydroxamate served as proper surrogates for adenine and ribose in isoleucyl adenylate, respectively.
Collapse
Affiliation(s)
- J Lee
- Laboratory of Medicinal Chemistry, College of Pharmacy, Seoul National University, Kwanak-Ku, South Korea.
| | | | | | | | | | | |
Collapse
|
30
|
Lee J, Kang SU, Kim SY, Kim SE, Kang MK, Jo YJ, Kim S. Ester and hydroxamate analogues of methionyl and isoleucyl adenylates as inhibitors of methionyl-tRNA and isoleucyl-tRNA synthetases. Bioorg Med Chem Lett 2001; 11:961-4. [PMID: 11327600 DOI: 10.1016/s0960-894x(01)00095-6] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The structure activity relationship on a series of ester and hydroxamate analogues of methionyl and isoleucyl adenylate has been investigated through introducing linkers between the 1'-position of ribose and adenine surrogates as methionyl-tRNA, and isoleucyl-tRNA synthetase inhibitors, respectively. The results indicate that ester analogue 23 was found to be a potent inhibitor of Escherichia coli methionyl-tRNA synthetase, and its interaction with the active site was proposed by a molecular modeling study.
Collapse
Affiliation(s)
- J Lee
- Laboratory of Medicinal Chemistry, College of Pharmacy, Seoul National University, Kwanak-Ku, South Korea.
| | | | | | | | | | | | | |
Collapse
|
31
|
Abstract
Four stable analogues of methionyl adenylate (3-6) were designed as inhibitors of methionyl-tRNA synthetase and synthesized from 2',3'-isopropylideneadenosine. They strongly inhibited aminoacylation activity of methionyl-tRNA synthetases isolated from Escherichia coli, Mycobacterium tuberculosis, Saccharomyces cerevisiae and human. Among the microorganisms tested, however, these chemicals showed the growth inhibition effect only on E. coli.
Collapse
Affiliation(s)
- J Lee
- Laboratory of Medicinal Chemistry, College of Pharmacy, Seoul National University, Korea
| | | | | | | | | | | | | |
Collapse
|
32
|
Abstract
A series of methionine analogues have been synthesized as inhibitors of methionyl-tRNA synthetase and evaluated for their inhibitory activities of E. coli methionyl-tRNA synthetase and bacterial growth. Among them, L-methionine hydroxamate 20 has proved to be the best inhibitor of the enzyme with Ki = 19 microM and showed a growth inhibition against E.coli JM 109, P. vulganis 6059 and C. freundii 8090.
Collapse
Affiliation(s)
- J Lee
- Laboratory of Medicinal Chemistry, College of Pharmacy, Seoul National University, Korea
| | | | | | | | | | | |
Collapse
|
33
|
Abstract
The active site of methionyl-tRNA synthetase (MetRS) possesses two functions: synthetic, which provides Met-tRNA for protein synthesis, and editing, which rejects inadvertently misactivated homocysteine. During editing, the side chain -SH group of homocysteine reacts with its activated carboxyl group forming a cyclic thioester, homocysteine thiolactone. As shown here, the side chain -SH and the activated carboxyl groups do not need to be present on the same molecule for the editing to occur. Thioester formation occurs when a thiol and activated methionine, in the form of Met-tRNA, are incubated with MetRS. Depending on the structure of thiols, methionine thioesters may undergo secondary acyl transfer reactions to cis amino, hydroxy, or carboxyl groups which yield methionine dipeptides, esters, or anhydrides, respectively. At saturating thiol concentrations, formation of some thiol derivatives of methionine is as fast as formation of homocysteine thiolactone. Thiol specificity of the reaction and noncompetitive inhibition by the cognate methionine, as well as structure-function studies of active site MetRS mutants, all indicate that there is a specific -SH binding subsite, distinct from the methionine binding subsite, in the synthetic/editing active site of MetRS.
Collapse
Affiliation(s)
- H Jakubowski
- Department of Microbiology & Molecular Genetics, UMDNJ--New Jersey Medical School, Newark 07103, USA
| |
Collapse
|
34
|
Hountondji C, Schmitter JM, Fukui T, Tagaya M, Blanquet S. Affinity labeling of aminoacyl-tRNA synthetases with adenosine triphosphopyridoxal: probing the Lys-Met-Ser-Lys-Ser signature sequence as the ATP-binding site in Escherichia coli methionyl-and valyl-tRNA synthetases. Biochemistry 1990; 29:11266-73. [PMID: 2271710 DOI: 10.1021/bi00503a016] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Pyridoxal 5'-triphospho-5'-adenosine (AP3-PL), the affinity labeling reagent specific for lysine residues in the nucleotide-binding site of several enzymes [Tagaya, M., & Fukui, T. (1986) Biochemistry 25, 2958-2964; Yagami, T., Tagaya, M., & Fukui, T. (1988) FEBS Lett. 229, 261-264], was used to identify the ATP-binding site of Escherichia coli methionyl-tRNA synthetase (MetRS). Incubation of this enzyme with AP3-PL followed by reduction with sodium borohydride resulted in a rapid inactivation of both the tRNA(Met) aminoacylation and the methionine-dependent ATP-PPi exchange activities. Complete inactivation corresponded to the incorporation of 0.98 mol of AP3-PL/mol of monomeric trypsin-modified MetRS. ATP or MgATP protected the enzyme from inactivation. The labeling with AP3-PL was also applied to E. coli valyl-tRNA synthetase (ValRS). Both the tRNA(Val) aminoacylation and the valine-dependent ATP-PPi exchange activities were abolished by the incorporation of 0.91 mol of AP3-PL/mol of monomeric ValRS. AP3-PL was found attached to lysine residues 335, 402, and 528 in the primary structure of MetRS. In the case of ValRS, the AP3-PL-labeled residues corresponded to lysines 557, 593, and 909. We therefore conclude that these lysines of MetRS and ValRS are directed toward the ATP-binding site of these synthetases, more specifically at or close to the subsite for the gamma-phosphate of ATP. AP3-PL-labeled Lys-335 of MetRS and Lys-557 of ValRS belong to the consensus tRNA CCA-binding Lys-Met-Ser-Lys-Ser sequence [Hountondji, C., Dessen, P., & Blanquet, S. (1986) Biochimie 68, 1071-1078].(ABSTRACT TRUNCATED AT 250 WORDS)
Collapse
Affiliation(s)
- C Hountondji
- Laboratoire de Biochimie, URA CNRS 240, Ecole Polytechnique, Palaiseau, France
| | | | | | | | | |
Collapse
|
35
|
Schwob E, Sanni A, Fasiolo F, Martin RP. Purification of the yeast mitochondrial methionyl-tRNA synthetase. Common and distinctive features of the cytoplasmic and mitochondrial isoenzymes. Eur J Biochem 1988; 178:235-42. [PMID: 3060359 DOI: 10.1111/j.1432-1033.1988.tb14448.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Yeast-mitochondrial methionyl-tRNA synthetase was purified 1060-fold from mitochondrial matrix proteins of Saccharomyces cerevisiae using a four-step procedure based on affinity chromatography (heparin-Ultrogel, tRNA(Met)-Sepharose, Agarose-hexyl-AMP) to yield to a single polypeptide of high specific activity (1800 U/mg). Like the cytoplasmic methionyl-tRNA synthetase (Mr 85,000), the mitochondrial isoenzyme is a monomer, but of significantly smaller polypeptide size (Mr 65,000). In contrast, the corresponding enzyme of Escherichia coli is a dimer (Mr 152,000) made up of identical subunits. The measured affinity constants of the purified mitochondrial enzyme for methionine and tRNA(Met) are similar to those of the cytoplasmic isoenzyme. However, the two yeast enzymes exhibit clearly different patterns of aminoacylation of heterologous yeast and E. coli tRNA(Met). Furthermore, polyclonal antibodies raised against the two proteins did not show any cross-reactivity by inhibition of enzymatic activity and by the highly sensitive immunoblotting technique, indicating that the two enzymes share little, if any, common antigenic determinants. Taken together, our results further support the belief that the yeast mitochondrial and cytoplasmic methionyl-tRNA synthetases are different proteins coded for by two distinct nuclear genes. Like the yeast cytoplasmic aminoacyl-tRNA synthetases, the mitochondrial enzymes displayed affinity for immobilized heparin. This distinguishes them from the corresponding enzymes of E. coli. Such an unexpected property of the mitochondrial enzymes suggests that they have acquired during evolution a domain for binding to negatively charged cellular components.
Collapse
Affiliation(s)
- E Schwob
- Institut de Biologie Moléculaire et Cellulaire du CNRS, Laboratoire de Biochemie, Strasbourg, France
| | | | | | | |
Collapse
|
36
|
Mayaux JF, Kalogerakos T, Brito KK, Blanquet S. Removal of the tightly bound zinc from Escherichia coli trypsin-modified methionyl-tRNA synthetase. Eur J Biochem 1982; 128:41-6. [PMID: 6756919 DOI: 10.1111/j.1432-1033.1982.tb06928.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The study of the behaviour of Escherichia coli methionyl-tRNA synthetase with chelating agents has shown that only 1,10-phenanthroline has an inhibitory effect on the tRNAMet aminoacylation activity. Under identical buffer conditions the isotopic [32P]PPi-ATP exchange activity is insensitive. Dialysis of the enzyme against 1,10-phenanthroline causes a slow loss of zinc from the enzyme which is paralleled by an irreversible loss of both the aminoacylation and isotopic exchange activities. The loss of zinc becomes faster upon the addition of small amounts of guanidine hydrochloride to the dialysis buffer containing phenanthroline, presumably by partially unfolding the protein. Studies of the reversible denaturation of the enzyme by 5 M guanidine hydrochloride shows that the inclusion of EDTA produces an enzyme species that has lost both zinc and activity. The inactive apoenzyme prepared in guanidine and EDTA can regain activity by dilution in a zinc-containing buffer.
Collapse
|
37
|
Hountondji C, Fayat G, Blanquet S. Complete inactivation and labeling of methionyl-tRNA synthetase by periodate-treated initiator tRNA in the presence of sodium cyanohydridoborate. Eur J Biochem 1979; 102:247-50. [PMID: 42539 DOI: 10.1111/j.1432-1033.1979.tb06286.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Methionyl-tRNA synthetase from Escherichia coli can react with periodate-treated tRNA to form a Schiff's base through the epsilon-amino group of a lysine within the enzymic active center and the 2',3'-aldehyde groups created at the 3'-terminal ribose of tRNA. At alkaline pH, the Schiff's base equilibrium can be continuously and specifically displaced by reduction in situ with sodium cyanohydridoborate, which on the other hand leaves intact the reacting aldehyde groups of oxidized tRNA. The effects of temperature, pH and of reducing agent concentration on the rate and extent of reduction of the Schiff's base are analysed. Conditions are described (37 degrees C, pH 8.0, in the presence of 1 mM cyanohydridoborate) which allowed rapid and complete conversion of the monomeric trypsin-modified methionyl-tRNA synthetase into its 1:1 covalent complex with tRNAfMet.
Collapse
|
38
|
Kushner JP, Boll D, Quagliana J, Dickman S. Elevated methionine-tRNA synthetase activity in human colon cancer. Proc Soc Exp Biol Med 1976; 153:273-6. [PMID: 995958 DOI: 10.3181/00379727-153-39526] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
|
39
|
Enouf J, Laurence F, Farrugia G, Blanchard P, Robert-Gero M. Comparative effect of methioninyl adenylate on the growth of Salmonella typhimurium and Pseudomonas aeruginosa. Arch Microbiol 1976; 110:129-34. [PMID: 189717 DOI: 10.1007/bf00416977] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The bacteriostatic effect of methioninyl adenylate(MAMP)--a specific inhibitor of the enzyme methionyl-tRNA synthetase--was investigated on Salmonella typhimurium and Pseudomonas aeruginosa. 0.1 mM of this molecule added to the culture, inhibits the growth of S. typhimurium. The inhibition is specifically reversible by 0.1 mM L-methionine. In the same conditions even 1-2 mM MAMP has a very slight effect on the growth rate of P. aeruginosa and only during the first two generations. The same observation was made with the two other members of the fluorescens group P.fluorescens and P.putida. The growth rate of P. testosteroni with 1 mM MAMP in the medium is similar to the growth rate of P. aeruginosa but the other member of the acidovorans group P. acidovorans is much more affected by the smae concentration of the inhibitor. --P. multivorans is inhibited by MAMP like P. acidovorans but with a somewhat higher yield at the end of the culture. --MAMP has no effect on P. alcaligenes. The possible reasons for the weak bacteriostatic effect of MAMP on P. aeruginosa were investigated. It was established that the inhibitor enters the cells and is not used as a carbon and energy source. The intracellular methionine concentration in S. typhimurium and in P. aeruginosa is about the same and does not increase when bacteria are cultivated with MAMP. The MTS of the two microorganisms is inhibited by MAMP in vitro to about the same extent. Furthermore the tRNAmet from P. aeruginosa are fully acylated after 3 to 4 generations with this compound. Nevertheless MAMP elicits higher MTS activity in P. aeruginosa and in P. acidovorans after 1 h of incubation. The most striking difference between S. typhimurium and P. aeruginosa is that the intra and extracellular level of 5'phosphodiesterase which degrades MAMP is 10-20 fold higher in the second than in the first species.
Collapse
|
40
|
Robert-Gero M, Lawrence F, Vigier P. Inhibition by methioninyl adenylate of focus formation by Rous sarcoma virus. Cancer Res 1975; 35:3571-6. [PMID: 172226] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Methioninyl adenylate is a specific and potent inhibitor of the enzyme methionyl-tRNA synthetase and, consequently, of protein biosynthesis. In cultures of chick embryo fibroblasts infected with Rous sarcoma virus, incubation for a 2-day period with 1 to 3 mM concentrations of this inhibitor, as late as 4 days after infection, irreversibly prevented subsequent formation of foci of transformed cells. Later addition could also elicit the irreversible disappearance of already existing foci, by phenotypic reversion and/or cell killing. Virus production in transformed cells and replication in newly infected cells were also inhibited but to a lesser degree. Under the same conditions, the same concentrations of methioninyl adenylate caused only a reversible growth arrest of normal cells. The selective toxicity of the inhibitor for transformed cells is not due to a greater affinity for the target enzyme, but it may be due to the fact that inhibition of protein biosynthesis is only partially reversible in these cells, whereas it is fully reversible in normal cells.
Collapse
|
41
|
Blanquet S, Fayat G, Poiret M, Waller JP. The mechanism of action of methionyl-tRNA synthetase from Escherichia coli. Inhibition by adenosine and 8-aminoadenosine of the amino-acid activation reaction. Eur J Biochem 1975; 51:567-71. [PMID: 168070 DOI: 10.1111/j.1432-1033.1975.tb03957.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Adenosine and 8-aminoadenosine, both competitive inhibitors of ATP-Mg2+ in the ATP-PPi exchange reaction catalyzed by methionyl-tRNA synthetase, are used to investigate the active center for methionyl-adenylate formation. Resolution of the kinetics parameters of the reaction indicates that methionine markedly enhances the affinity of the nucleosides for the enzyme, providing evidence for coupling between the sites for amino acid and the nucleoside moiety of ATP. Furthermore, occupation of both of these sites is a prerequisite for binding of pyrophosphate. Introduction of an amino group in position 8 of the adenine ring strongly increases the affinity constants for the nucleoside and for pyrophosphate in the coupled reactions described above.
Collapse
|