1
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Chen N, Ehmann DE, Crooker R, Derakhchan K, Fang X, Felice B, Galbreath EJ, Glaus C, Gu H, Huang Y, Li C, Li X, Liu N, Palmieri K, Simic D, Sypek J, Thompson S, Winkelmann CT, Choi VW. Evaluation of gene therapy for cross-correction of somatic organs and the CNS in mucopolysaccharidosis II in rodents and non-human primates. Molecular Therapy - Methods & Clinical Development 2023. [DOI: 10.1016/j.omtm.2023.03.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/30/2023]
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2
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Iskenderian A, Liu N, Deng Q, Huang Y, Shen C, Palmieri K, Crooker R, Lundberg D, Kastrapeli N, Pescatore B, Romashko A, Dumas J, Comeau R, Norton A, Pan J, Rong H, Derakhchan K, Ehmann DE. Myostatin and activin blockade by engineered follistatin results in hypertrophy and improves dystrophic pathology in mdx mouse more than myostatin blockade alone. Skelet Muscle 2018; 8:34. [PMID: 30368252 PMCID: PMC6204036 DOI: 10.1186/s13395-018-0180-z] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2018] [Accepted: 10/14/2018] [Indexed: 01/03/2023] Open
Abstract
BACKGROUND Myostatin antagonists are being developed as therapies for Duchenne muscular dystrophy due to their strong hypertrophic effects on skeletal muscle. Engineered follistatin has the potential to combine the hypertrophy of myostatin antagonism with the anti-inflammatory and anti-fibrotic effects of activin A antagonism. METHODS Engineered follistatin was administered to C57BL/6 mice for 4 weeks, and muscle mass and myofiber size was measured. In the mdx model, engineered follistatin was dosed for 12 weeks in two studies comparing to an Fc fusion of the activin IIB receptor or an anti-myostatin antibody. Functional measurements of grip strength and tetanic force were combined with tissue analysis for markers of necrosis, inflammation, and fibrosis to evaluate improvement in dystrophic pathology. RESULTS In wild-type and mdx mice, dose-dependent increases in muscle mass and quadriceps myofiber size were observed for engineered follistatin. In mdx, increases in grip strength and tetanic force were combined with improvements in muscle markers for necrosis, inflammation, and fibrosis. Improvements in dystrophic pathology were greater for engineered follistatin than the anti-myostatin antibody. CONCLUSIONS Engineered follistatin generated hypertrophy and anti-fibrotic effects in the mdx model.
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Affiliation(s)
- Andrea Iskenderian
- Discovery Therapeutics, Shire Pharmaceuticals, Lexington, MA, USA.,Drug Discovery, Shire, Cambridge, MA, USA
| | - Nan Liu
- Discovery Therapeutics, Shire Pharmaceuticals, Lexington, MA, USA.,Drug Discovery, Shire, Cambridge, MA, USA
| | - Qingwei Deng
- Research, Shire Pharmaceuticals, Lexington, MA, 02421, USA.,Drug Discovery, Shire, Cambridge, MA, USA
| | - Yan Huang
- Discovery Therapeutics, Shire Pharmaceuticals, Lexington, MA, USA.,Drug Discovery, Shire, Cambridge, MA, USA
| | - Chuan Shen
- Discovery Therapeutics, Shire Pharmaceuticals, Lexington, MA, USA.,Drug Discovery, Shire, Cambridge, MA, USA
| | - Kathleen Palmieri
- Research, Shire Pharmaceuticals, Lexington, MA, 02421, USA.,Drug Discovery, Shire, Cambridge, MA, USA
| | - Robert Crooker
- Research, Shire Pharmaceuticals, Lexington, MA, 02421, USA.,Drug Discovery, Shire, Cambridge, MA, USA
| | - Dianna Lundberg
- Discovery Therapeutics, Shire Pharmaceuticals, Lexington, MA, USA.,Drug Discovery, Shire, Cambridge, MA, USA
| | - Niksa Kastrapeli
- Discovery Therapeutics, Shire Pharmaceuticals, Lexington, MA, USA.,Drug Discovery, Shire, Cambridge, MA, USA
| | - Brian Pescatore
- Discovery Therapeutics, Shire Pharmaceuticals, Lexington, MA, USA.,Drug Discovery, Shire, Cambridge, MA, USA
| | - Alla Romashko
- Discovery Therapeutics, Shire Pharmaceuticals, Lexington, MA, USA.,Drug Discovery, Shire, Cambridge, MA, USA
| | - John Dumas
- Discovery Therapeutics, Shire Pharmaceuticals, Lexington, MA, USA.,Drug Discovery, Shire, Cambridge, MA, USA
| | - Robert Comeau
- Discovery Therapeutics, Shire Pharmaceuticals, Lexington, MA, USA.,Drug Discovery, Shire, Cambridge, MA, USA
| | - Angela Norton
- Discovery Therapeutics, Shire Pharmaceuticals, Lexington, MA, USA.,Drug Discovery, Shire, Cambridge, MA, USA
| | - Jing Pan
- Discovery Therapeutics, Shire Pharmaceuticals, Lexington, MA, USA.,Drug Discovery, Shire, Cambridge, MA, USA
| | - Haojing Rong
- Nonclinical Development, Shire Pharmaceuticals, Lexington, MA, USA.,Drug Discovery, Shire, Cambridge, MA, USA
| | - Katayoun Derakhchan
- Nonclinical Development, Shire Pharmaceuticals, Lexington, MA, USA.,Drug Discovery, Shire, Cambridge, MA, USA
| | - David E Ehmann
- Research, Shire Pharmaceuticals, Lexington, MA, 02421, USA. .,Drug Discovery, Shire, Cambridge, MA, USA.
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3
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Durand-Réville TF, Guler S, Comita-Prevoir J, Chen B, Bifulco N, Huynh H, Lahiri S, Shapiro AB, McLeod SM, Carter NM, Moussa SH, Velez-Vega C, Olivier NB, McLaughlin R, Gao N, Thresher J, Palmer T, Andrews B, Giacobbe RA, Newman JV, Ehmann DE, de Jonge B, O'Donnell J, Mueller JP, Tommasi RA, Miller AA. ETX2514 is a broad-spectrum β-lactamase inhibitor for the treatment of drug-resistant Gram-negative bacteria including Acinetobacter baumannii. Nat Microbiol 2017; 2:17104. [PMID: 28665414 DOI: 10.1038/nmicrobiol.2017.104] [Citation(s) in RCA: 168] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2016] [Accepted: 05/25/2017] [Indexed: 11/09/2022]
Abstract
Multidrug-resistant (MDR) bacterial infections are a serious threat to public health. Among the most alarming resistance trends is the rapid rise in the number and diversity of β-lactamases, enzymes that inactivate β-lactams, a class of antibiotics that has been a therapeutic mainstay for decades. Although several new β-lactamase inhibitors have been approved or are in clinical trials, their spectra of activity do not address MDR pathogens such as Acinetobacter baumannii. This report describes the rational design and characterization of expanded-spectrum serine β-lactamase inhibitors that potently inhibit clinically relevant class A, C and D β-lactamases and penicillin-binding proteins, resulting in intrinsic antibacterial activity against Enterobacteriaceae and restoration of β-lactam activity in a broad range of MDR Gram-negative pathogens. One of the most promising combinations is sulbactam-ETX2514, whose potent antibacterial activity, in vivo efficacy against MDR A. baumannii infections and promising preclinical safety demonstrate its potential to address this significant unmet medical need.
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Affiliation(s)
| | - Satenig Guler
- Entasis Therapeutics, 35 Gatehouse Drive, Waltham, Massachusetts 02451, USA
| | | | - Brendan Chen
- AstraZeneca, 35 Gatehouse Drive, Waltham, Massachusetts 02451, USA
| | - Neil Bifulco
- AstraZeneca, 35 Gatehouse Drive, Waltham, Massachusetts 02451, USA
| | - Hoan Huynh
- AstraZeneca, 35 Gatehouse Drive, Waltham, Massachusetts 02451, USA
| | - Sushmita Lahiri
- AstraZeneca, 35 Gatehouse Drive, Waltham, Massachusetts 02451, USA
| | - Adam B Shapiro
- Entasis Therapeutics, 35 Gatehouse Drive, Waltham, Massachusetts 02451, USA
| | - Sarah M McLeod
- Entasis Therapeutics, 35 Gatehouse Drive, Waltham, Massachusetts 02451, USA
| | - Nicole M Carter
- Entasis Therapeutics, 35 Gatehouse Drive, Waltham, Massachusetts 02451, USA
| | - Samir H Moussa
- Entasis Therapeutics, 35 Gatehouse Drive, Waltham, Massachusetts 02451, USA
| | - Camilo Velez-Vega
- Entasis Therapeutics, 35 Gatehouse Drive, Waltham, Massachusetts 02451, USA
| | - Nelson B Olivier
- AstraZeneca, 35 Gatehouse Drive, Waltham, Massachusetts 02451, USA
| | | | - Ning Gao
- AstraZeneca, 35 Gatehouse Drive, Waltham, Massachusetts 02451, USA
| | - Jason Thresher
- AstraZeneca, 35 Gatehouse Drive, Waltham, Massachusetts 02451, USA
| | - Tiffany Palmer
- AstraZeneca, 35 Gatehouse Drive, Waltham, Massachusetts 02451, USA
| | - Beth Andrews
- AstraZeneca, 35 Gatehouse Drive, Waltham, Massachusetts 02451, USA
| | | | - Joseph V Newman
- AstraZeneca, 35 Gatehouse Drive, Waltham, Massachusetts 02451, USA
| | - David E Ehmann
- AstraZeneca, 35 Gatehouse Drive, Waltham, Massachusetts 02451, USA
| | | | - John O'Donnell
- Entasis Therapeutics, 35 Gatehouse Drive, Waltham, Massachusetts 02451, USA
| | - John P Mueller
- Entasis Therapeutics, 35 Gatehouse Drive, Waltham, Massachusetts 02451, USA
| | - Rubén A Tommasi
- Entasis Therapeutics, 35 Gatehouse Drive, Waltham, Massachusetts 02451, USA
| | - Alita A Miller
- Entasis Therapeutics, 35 Gatehouse Drive, Waltham, Massachusetts 02451, USA
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4
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Kim A, Kutschke A, Ehmann DE, Patey SA, Crandon JL, Gorseth E, Miller AA, McLaughlin RE, Blinn CM, Chen A, Nayar AS, Dangel B, Tsai AS, Rooney MT, Murphy-Benenato KE, Eakin AE, Nicolau DP. Pharmacodynamic Profiling of a Siderophore-Conjugated Monocarbam in Pseudomonas aeruginosa: Assessing the Risk for Resistance and Attenuated Efficacy. Antimicrob Agents Chemother 2015; 59:7743-52. [PMID: 26438502 PMCID: PMC4649189 DOI: 10.1128/aac.00831-15] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2015] [Accepted: 09/29/2015] [Indexed: 01/05/2023] Open
Abstract
The objective of this study was to investigate the risk of attenuated efficacy due to adaptive resistance for the siderophore-conjugated monocarbam SMC-3176 in Pseudomonas aeruginosa by using a pharmacokinetic/pharmacodynamic (PK/PD) approach. MICs were determined in cation-adjusted Mueller-Hinton broth (MHB) and in Chelex-treated, dialyzed MHB (CDMHB). Spontaneous resistance was assessed at 2× to 16× the MIC and the resulting mutants sequenced. Efficacy was evaluated in a neutropenic mouse thigh model at 3.13 to 400 mg/kg of body weight every 3 h for 24 h and analyzed for association with free time above the MIC (fT>MIC). To closer emulate the conditions of the in vivo model, we developed a novel assay testing activity mouse whole blood (WB). All mutations were found in genes related to iron uptake: piuA, piuC, pirR, fecI, and pvdS. Against four P. aeruginosa isolates, SMC-3176 displayed predictable efficacy corresponding to the fT>MIC using the MIC in CDMHB (R(2) = 0.968 to 0.985), with stasis to 2-log kill achieved at 59.4 to 81.1%. Efficacy did not translate for P. aeruginosa isolate JJ 4-36, as the in vivo responses were inconsistent with fT>MIC exposures and implied a threshold concentration that was greater than the MIC. The results of the mouse WB assay indicated that efficacy was not predictable using the MIC for JJ 4-36 and four additional isolates, against which in vivo failures of another siderophore-conjugated β-lactam were previously reported. SMC-3176 carries a risk of attenuated efficacy in P. aeruginosa due to rapid adaptive resistance preventing entry via the siderophore-mediated iron uptake systems. Substantial in vivo testing is warranted for compounds using the siderophore approach to thoroughly screen for this in vitro-in vivo disconnect in P. aeruginosa.
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Affiliation(s)
- Aryun Kim
- Infection Innovative Medicines, AstraZeneca Pharmaceuticals LP, Waltham, Massachusetts, USA
| | - Amy Kutschke
- Infection Innovative Medicines, AstraZeneca Pharmaceuticals LP, Waltham, Massachusetts, USA
| | - David E Ehmann
- Infection Innovative Medicines, AstraZeneca Pharmaceuticals LP, Waltham, Massachusetts, USA
| | - Sara A Patey
- Infection Innovative Medicines, AstraZeneca Pharmaceuticals LP, Waltham, Massachusetts, USA
| | - Jared L Crandon
- Center for Anti-Infective Research and Development, Hartford Hospital, Hartford, Connecticut, USA
| | - Elise Gorseth
- Infection Innovative Medicines, AstraZeneca Pharmaceuticals LP, Waltham, Massachusetts, USA
| | - Alita A Miller
- Infection Innovative Medicines, AstraZeneca Pharmaceuticals LP, Waltham, Massachusetts, USA
| | - Robert E McLaughlin
- Infection Innovative Medicines, AstraZeneca Pharmaceuticals LP, Waltham, Massachusetts, USA
| | - Christina M Blinn
- Infection Innovative Medicines, AstraZeneca Pharmaceuticals LP, Waltham, Massachusetts, USA
| | - April Chen
- Infection Innovative Medicines, AstraZeneca Pharmaceuticals LP, Waltham, Massachusetts, USA
| | - Asha S Nayar
- Infection Innovative Medicines, AstraZeneca Pharmaceuticals LP, Waltham, Massachusetts, USA
| | - Brian Dangel
- Infection Innovative Medicines, AstraZeneca Pharmaceuticals LP, Waltham, Massachusetts, USA
| | - Andy S Tsai
- Infection Innovative Medicines, AstraZeneca Pharmaceuticals LP, Waltham, Massachusetts, USA
| | - Michael T Rooney
- Infection Innovative Medicines, AstraZeneca Pharmaceuticals LP, Waltham, Massachusetts, USA
| | | | - Ann E Eakin
- Infection Innovative Medicines, AstraZeneca Pharmaceuticals LP, Waltham, Massachusetts, USA
| | - David P Nicolau
- Center for Anti-Infective Research and Development, Hartford Hospital, Hartford, Connecticut, USA
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5
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Kern G, Palmer T, Ehmann DE, Shapiro AB, Andrews B, Basarab GS, Doig P, Fan J, Gao N, Mills SD, Mueller J, Sriram S, Thresher J, Walkup GK. Inhibition of Neisseria gonorrhoeae Type II Topoisomerases by the Novel Spiropyrimidinetrione AZD0914. J Biol Chem 2015; 290:20984-20994. [PMID: 26149691 DOI: 10.1074/jbc.m115.663534] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2015] [Indexed: 11/06/2022] Open
Abstract
We characterized the inhibition of Neisseria gonorrhoeae type II topoisomerases gyrase and topoisomerase IV by AZD0914 (AZD0914 will be henceforth known as ETX0914 (Entasis Therapeutics)), a novel spiropyrimidinetrione antibacterial compound that is currently in clinical trials for treatment of drug-resistant gonorrhea. AZD0914 has potent bactericidal activity against N. gonorrhoeae, including multidrug-resistant strains and key Gram-positive, fastidious Gram-negative, atypical, and anaerobic bacterial species (Huband, M. D., Bradford, P. A., Otterson, L. G., Basrab, G. S., Giacobe, R. A., Patey, S. A., Kutschke, A. C., Johnstone, M. R., Potter, M. E., Miller, P. F., and Mueller, J. P. (2014) In Vitro Antibacterial Activity of AZD0914: A New Spiropyrimidinetrione DNA Gyrase/Topoisomerase Inhibitor with Potent Activity against Gram-positive, Fastidious Gram-negative, and Atypical Bacteria. Antimicrob. Agents Chemother. 59, 467-474). AZD0914 inhibited DNA biosynthesis preferentially to other macromolecules in Escherichia coli and induced the SOS response to DNA damage in E. coli. AZD0914 stabilized the enzyme-DNA cleaved complex for N. gonorrhoeae gyrase and topoisomerase IV. The potency of AZD0914 for inhibition of supercoiling and the stabilization of cleaved complex by N. gonorrhoeae gyrase increased in a fluoroquinolone-resistant mutant enzyme. When a mutation, conferring mild resistance to AZD0914, was present in the fluoroquinolone-resistant mutant, the potency of ciprofloxacin for inhibition of supercoiling and stabilization of cleaved complex was increased greater than 20-fold. In contrast to ciprofloxacin, religation of the cleaved DNA did not occur in the presence of AZD0914 upon removal of magnesium from the DNA-gyrase-inhibitor complex. AZD0914 had relatively low potency for inhibition of human type II topoisomerases α and β.
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Affiliation(s)
- Gunther Kern
- Departments of Biosciences, Discovery Sciences, AstraZeneca R&D Boston, Waltham, Massachusetts 02451.
| | - Tiffany Palmer
- Departments of Biosciences, Discovery Sciences, AstraZeneca R&D Boston, Waltham, Massachusetts 02451
| | - David E Ehmann
- Departments of Biosciences, Discovery Sciences, AstraZeneca R&D Boston, Waltham, Massachusetts 02451
| | - Adam B Shapiro
- Departments of Biosciences, Discovery Sciences, AstraZeneca R&D Boston, Waltham, Massachusetts 02451
| | - Beth Andrews
- Departments of Biosciences, Discovery Sciences, AstraZeneca R&D Boston, Waltham, Massachusetts 02451
| | - Gregory S Basarab
- Departments of Chemistry, Infection Innovative Medicines Unit, Discovery Sciences, AstraZeneca R&D Boston, Waltham, Massachusetts 02451
| | - Peter Doig
- Department of Structure and Biophysics, Discovery Sciences, AstraZeneca R&D Boston, Waltham, Massachusetts 02451
| | - Jun Fan
- Departments of Biosciences, Discovery Sciences, AstraZeneca R&D Boston, Waltham, Massachusetts 02451
| | - Ning Gao
- Department of Structure and Biophysics, Discovery Sciences, AstraZeneca R&D Boston, Waltham, Massachusetts 02451
| | - Scott D Mills
- Departments of Biosciences, Discovery Sciences, AstraZeneca R&D Boston, Waltham, Massachusetts 02451
| | - John Mueller
- Departments of Biosciences, Discovery Sciences, AstraZeneca R&D Boston, Waltham, Massachusetts 02451
| | - Shubha Sriram
- Departments of Biosciences, Discovery Sciences, AstraZeneca R&D Boston, Waltham, Massachusetts 02451
| | - Jason Thresher
- Department of Structure and Biophysics, Discovery Sciences, AstraZeneca R&D Boston, Waltham, Massachusetts 02451
| | - Grant K Walkup
- Departments of Biosciences, Discovery Sciences, AstraZeneca R&D Boston, Waltham, Massachusetts 02451
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6
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Walkup GK, You Z, Ross PL, Allen EKH, Daryaee F, Hale MR, O'Donnell J, Ehmann DE, Schuck VJA, Buurman ET, Choy AL, Hajec L, Murphy-Benenato K, Marone V, Patey SA, Grosser LA, Johnstone M, Walker SG, Tonge PJ, Fisher SL. Translating slow-binding inhibition kinetics into cellular and in vivo effects. Nat Chem Biol 2015; 11:416-23. [PMID: 25894085 DOI: 10.1038/nchembio.1796] [Citation(s) in RCA: 110] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2014] [Accepted: 03/19/2015] [Indexed: 01/18/2023]
Abstract
Many drug candidates fail in clinical trials owing to a lack of efficacy from limited target engagement or an insufficient therapeutic index. Minimizing off-target effects while retaining the desired pharmacodynamic (PD) response can be achieved by reduced exposure for drugs that display kinetic selectivity in which the drug-target complex has a longer half-life than off-target-drug complexes. However, though slow-binding inhibition kinetics are a key feature of many marketed drugs, prospective tools that integrate drug-target residence time into predictions of drug efficacy are lacking, hindering the integration of drug-target kinetics into the drug discovery cascade. Here we describe a mechanistic PD model that includes drug-target kinetic parameters, including the on- and off-rates for the formation and breakdown of the drug-target complex. We demonstrate the utility of this model by using it to predict dose response curves for inhibitors of the LpxC enzyme from Pseudomonas aeruginosa in an animal model of infection.
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Affiliation(s)
- Grant K Walkup
- Infection Innovative Medicines Unit, AstraZeneca Research and Development, Waltham, Massachusetts, USA
| | - Zhiping You
- Infection Innovative Medicines Unit, AstraZeneca Research and Development, Waltham, Massachusetts, USA
| | - Philip L Ross
- Infection Innovative Medicines Unit, AstraZeneca Research and Development, Waltham, Massachusetts, USA
| | - Eleanor K H Allen
- Institute for Chemical Biology and Drug Discovery, Department of Chemistry, Stony Brook University, Stony Brook, New York, USA
| | - Fereidoon Daryaee
- Institute for Chemical Biology and Drug Discovery, Department of Chemistry, Stony Brook University, Stony Brook, New York, USA
| | - Michael R Hale
- Infection Innovative Medicines Unit, AstraZeneca Research and Development, Waltham, Massachusetts, USA
| | - John O'Donnell
- Infection Innovative Medicines Unit, AstraZeneca Research and Development, Waltham, Massachusetts, USA
| | - David E Ehmann
- Infection Innovative Medicines Unit, AstraZeneca Research and Development, Waltham, Massachusetts, USA
| | - Virna J A Schuck
- Infection Innovative Medicines Unit, AstraZeneca Research and Development, Waltham, Massachusetts, USA
| | - Ed T Buurman
- Infection Innovative Medicines Unit, AstraZeneca Research and Development, Waltham, Massachusetts, USA
| | - Allison L Choy
- Infection Innovative Medicines Unit, AstraZeneca Research and Development, Waltham, Massachusetts, USA
| | - Laurel Hajec
- Infection Innovative Medicines Unit, AstraZeneca Research and Development, Waltham, Massachusetts, USA
| | - Kerry Murphy-Benenato
- Infection Innovative Medicines Unit, AstraZeneca Research and Development, Waltham, Massachusetts, USA
| | - Valerie Marone
- Infection Innovative Medicines Unit, AstraZeneca Research and Development, Waltham, Massachusetts, USA
| | - Sara A Patey
- Infection Innovative Medicines Unit, AstraZeneca Research and Development, Waltham, Massachusetts, USA
| | - Lena A Grosser
- Infection Innovative Medicines Unit, AstraZeneca Research and Development, Waltham, Massachusetts, USA
| | - Michele Johnstone
- Infection Innovative Medicines Unit, AstraZeneca Research and Development, Waltham, Massachusetts, USA
| | - Stephen G Walker
- Department of Oral Biology and Pathology, Stony Brook University, Stony Brook, New York, USA
| | - Peter J Tonge
- Institute for Chemical Biology and Drug Discovery, Department of Chemistry, Stony Brook University, Stony Brook, New York, USA
| | - Stewart L Fisher
- Infection Innovative Medicines Unit, AstraZeneca Research and Development, Waltham, Massachusetts, USA
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7
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Murphy-Benenato KE, Bhagunde PR, Chen A, Davis HE, Durand-Réville TF, Ehmann DE, Galullo V, Harris JJ, Hatoum-Mokdad H, Jahić H, Kim A, Manjunatha MR, Manyak EL, Mueller J, Patey S, Quiroga O, Rooney M, Sha L, Shapiro AB, Sylvester M, Tan B, Tsai AS, Uria-Nickelsen M, Wu Y, Zambrowski M, Zhao SX. Discovery of Efficacious Pseudomonas aeruginosa-Targeted Siderophore-Conjugated Monocarbams by Application of a Semi-mechanistic Pharmacokinetic/Pharmacodynamic Model. J Med Chem 2015; 58:2195-205. [DOI: 10.1021/jm501506f] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | - M. R. Manjunatha
- Infection
Innovative Medicines, AstraZeneca India Pvt. Ltd., Bellary Road, Bangalore 560024, India
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8
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Lahiri SD, Mangani S, Jahić H, Benvenuti M, Durand-Reville TF, De Luca F, Ehmann DE, Rossolini GM, Alm RA, Docquier JD. Molecular basis of selective inhibition and slow reversibility of avibactam against class D carbapenemases: a structure-guided study of OXA-24 and OXA-48. ACS Chem Biol 2015; 10:591-600. [PMID: 25406838 DOI: 10.1021/cb500703p] [Citation(s) in RCA: 78] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The Class D (or OXA-type) β-lactamases have expanded to be the most diverse group of serine β-lactamases with a highly heterogeneous β-lactam hydrolysis profile and are typically resistant to marketed β-lactamase inhibitors. Class D enzymes are increasingly found in multidrug resistant (MDR) Acinetobacter baumannii, Pseudomonas aeruginosa, and various species of the Enterobacteriaceae and are posing a serious threat to the clinical utility of β-lactams including the carbapenems, which are typically reserved as the drugs of last resort. Avibactam, a novel non-β-lactam β-lactamase inhibitor, not only inhibits all class A and class C β-lactamases but also has the promise of inhibition of certain OXA enzymes, thus extending the antibacterial activity of the β-lactam used in combination to the organisms that produce these enzymes. X-ray structures of OXA-24 and OXA-48 in complex with avibactam revealed the binding mode of this inhibitor in this diverse class of enzymes and provides a rationale for selective inhibition of OXA-48 members. Additionally, various subunits of the OXA-48 structure in the asymmetric unit provide snapshots of different states of the inhibited enzyme. Overall, these data provide the first structural evidence of the exceptionally slow reversibility observed with avibactam in class D β-lactamases. Mechanisms for acylation and deacylation of avibactam by class D enzymes are proposed, and the likely extent of inhibition of class D β-lactamases by avibactam is discussed.
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Affiliation(s)
| | | | | | | | | | | | | | - Gian Maria Rossolini
- Department of Experimental and Clinical
Medicine, University of Florence, Florence I-50134, Italy
- Clinical
Microbiology and Virology Unit, Florence Careggi University Hospital, Florence I-50134, Italy
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9
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Ehmann DE, Lahiri SD. Novel compounds targeting bacterial DNA topoisomerase/DNA gyrase. Curr Opin Pharmacol 2014; 18:76-83. [PMID: 25271174 DOI: 10.1016/j.coph.2014.09.007] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2014] [Accepted: 09/12/2014] [Indexed: 02/08/2023]
Abstract
Among the targets for the development of new antibacterial agents, bacterial topoisomerases remain a vibrant area of discovery. A structurally diverse set of inhibitors that bind to the adenosine 5'-triphosphate (ATP) site of type II topoisomerases have been disclosed recently. Seven compounds with this mechanism are highlighted, focusing on antibacterial potency and spectrum, as well as examples of in vivo efficacy against pathogens including Staphylococcus aureus and Mycobacterium tuberculosis. Five compounds from two structural classes are exemplified that are inhibitors that bind to the catalytic site of DNA gyrase and topoisomerase IV. The pharmacokinetic and pharmacodynamic properties of these molecules, derived from in vivo efficacy against Gram-positive and Gram-negative pathogens, define the potential for these agents with broad-spectrum and targeted-spectrum clinical utilities.
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Affiliation(s)
- David E Ehmann
- Infection Innovative Medicines Unit, AstraZeneca R&D Boston, 35 Gatehouse Drive, Waltham, MA 02451, USA.
| | - Sushmita D Lahiri
- Infection Innovative Medicines Unit, AstraZeneca R&D Boston, 35 Gatehouse Drive, Waltham, MA 02451, USA
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10
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Ehmann DE, Jahic H, Ross PL, Gu RF, Hu J, Durand-Réville TF, Lahiri S, Thresher J, Livchak S, Gao N, Palmer T, Walkup GK, Fisher SL. Kinetics of avibactam inhibition against Class A, C, and D β-lactamases. J Biol Chem 2013; 288:27960-71. [PMID: 23913691 DOI: 10.1074/jbc.m113.485979] [Citation(s) in RCA: 270] [Impact Index Per Article: 24.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Avibactam is a non-β-lactam β-lactamase inhibitor with a spectrum of activity that includes β-lactamase enzymes of classes A, C, and selected D examples. In this work acylation and deacylation rates were measured against the clinically important enzymes CTX-M-15, KPC-2, Enterobacter cloacae AmpC, Pseudomonas aeruginosa AmpC, OXA-10, and OXA-48. The efficiency of acylation (k2/Ki) varied across the enzyme spectrum, from 1.1 × 10(1) m(-1)s(-1) for OXA-10 to 1.0 × 10(5) for CTX-M-15. Inhibition of OXA-10 was shown to follow the covalent reversible mechanism, and the acylated OXA-10 displayed the longest residence time for deacylation, with a half-life of greater than 5 days. Across multiple enzymes, acyl enzyme stability was assessed by mass spectrometry. These inhibited enzyme forms were stable to rearrangement or hydrolysis, with the exception of KPC-2. KPC-2 displayed a slow hydrolytic route that involved fragmentation of the acyl-avibactam complex. The identity of released degradation products was investigated, and a possible mechanism for the slow deacylation from KPC-2 is proposed.
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Affiliation(s)
- David E Ehmann
- From the Infection Innovative Medicines Unit and the Discovery Sciences Innovative Medicines Unit, AstraZeneca R&D Boston, Waltham, Massachusetts 02451
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Reck F, Alm RA, Brassil P, Newman JV, Ciaccio P, McNulty J, Barthlow H, Goteti K, Breen J, Comita-Prevoir J, Cronin M, Ehmann DE, Geng B, Godfrey AA, Fisher SL. Novel N-Linked Aminopiperidine Inhibitors of Bacterial Topoisomerase Type II with Reduced pKa: Antibacterial Agents with an Improved Safety Profile. J Med Chem 2012; 55:6916-33. [DOI: 10.1021/jm300690s] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | | | | | - Andrew Aydon Godfrey
- Pharmaceutical
Development, Chemical Sciences, AstraZeneca, Silk Road Business Park, Macclesfield, SK10 4TG Cheshire, England
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Ehmann DE, Jahić H, Ross PL, Gu RF, Hu J, Kern G, Walkup GK, Fisher SL. Avibactam is a covalent, reversible, non-β-lactam β-lactamase inhibitor. Proc Natl Acad Sci U S A 2012; 109:11663-8. [PMID: 22753474 PMCID: PMC3406822 DOI: 10.1073/pnas.1205073109] [Citation(s) in RCA: 369] [Impact Index Per Article: 30.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Avibactam is a β-lactamase inhibitor that is in clinical development, combined with β-lactam partners, for the treatment of bacterial infections comprising gram-negative organisms. Avibactam is a structural class of inhibitor that does not contain a β-lactam core but maintains the capacity to covalently acylate its β-lactamase targets. Using the TEM-1 enzyme, we characterized avibactam inhibition by measuring the on-rate for acylation and the off-rate for deacylation. The deacylation off-rate was 0.045 min(-1), which allowed investigation of the deacylation route from TEM-1. Using NMR and MS, we showed that deacylation proceeds through regeneration of intact avibactam and not hydrolysis. Other than TEM-1, four additional clinically relevant β-lactamases were shown to release intact avibactam after being acylated. We showed that avibactam is a covalent, slowly reversible inhibitor, which is a unique mechanism of inhibition among β-lactamase inhibitors.
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Affiliation(s)
- David E Ehmann
- Infection Innovative Medicines Unit, AstraZeneca Research & Development Boston, Waltham, MA 02451, USA.
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Ehmann DE, Demeritt JE, Hull KG, Fisher SL. Biochemical characterization of an inhibitor of Escherichia coli UDP-N-acetylmuramyl-l-alanine ligase. Biochim Biophys Acta 2004; 1698:167-74. [PMID: 15134649 DOI: 10.1016/j.bbapap.2003.11.006] [Citation(s) in RCA: 29] [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] [Subscribe] [Scholar Register] [Received: 07/29/2003] [Accepted: 11/07/2003] [Indexed: 11/24/2022]
Abstract
UDP-N-acetylmuramyl-l-alanine ligase (MurC) is an essential bacterial enzyme involved in peptidoglycan biosynthesis and a target for the discovery of novel antibacterial agents. As a result of a high-throughput screen (HTS) against a chemical library for inhibitors of MurC, a series of benzofuran acyl-sulfonamides was identified as potential leads. One of these compounds, Compound A, inhibited Escherichia coli MurC with an IC(50) of 2.3 microM. Compound A exhibited time-dependent, partially reversible inhibition of E. coli MurC. Kinetic studies revealed a mode of inhibition consistent with the compound acting competitively with the MurC substrates ATP and UDP-N-acetyl-muramic acid (UNAM) with a K(i) of 4.5 microM against ATP and 6.3 microM against UNAM. Fluorescence binding experiments yielded a K(d) of 3.1 microM for the compound binding to MurC. Compound A also exhibited high-affinity binding to bovine serum albumin (BSA) as evidenced by a severe reduction in MurC inhibition upon addition of BSA. This finding is consistent with the high lipophilicity of the compound. Advancement of this compound series for further drug development will require reduction of albumin binding.
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Affiliation(s)
- David E Ehmann
- Department of Biochemistry, Infection Discovery, Cancer and Infection Research Area, AstraZeneca R&D Boston, 35 Gatehouse Drive, Waltham, MA 02451, USA.
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Keating TA, Ehmann DE, Kohli RM, Marshall CG, Trauger JW, Walsh CT. Chain termination steps in nonribosomal peptide synthetase assembly lines: directed acyl-S-enzyme breakdown in antibiotic and siderophore biosynthesis. Chembiochem 2001; 2:99-107. [PMID: 11828432 DOI: 10.1002/1439-7633(20010202)2:2<99::aid-cbic99>3.0.co;2-3] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- T A Keating
- Harvard Medical School, Department of Biological Chemistry and Molecular Pharmacology, 240 Longwood Avenue, Boston, MA 02115, USA
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Keating TA, Ehmann DE, Kohli RM, Marshall CG, Trauger JW, Walsh CT. Chain termination steps in nonribosomal peptide synthetase assembly lines: directed acyl-S-enzyme breakdown in antibiotic and siderophore biosynthesis. Chembiochem 2001. [PMID: 11828432 DOI: 10.1002/1439-7633(20010202)2:23.0.co;2-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/29/2023]
Affiliation(s)
- T A Keating
- Harvard Medical School, Department of Biological Chemistry and Molecular Pharmacology, 240 Longwood Avenue, Boston, MA 02115, USA
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Keating TA, Ehmann DE, Kohli RM, Marshall CG, Trauger JW, Walsh CT. Cover Picture. Chembiochem 2001. [DOI: 10.1002/1439-7633(20010202)2:2<91::aid-cbic91>3.0.co;2-e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Ehmann DE, Trauger JW, Stachelhaus T, Walsh CT. Aminoacyl-SNACs as small-molecule substrates for the condensation domains of nonribosomal peptide synthetases. Chem Biol 2000; 7:765-72. [PMID: 11033080 DOI: 10.1016/s1074-5521(00)00022-3] [Citation(s) in RCA: 85] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
BACKGROUND Nonribosomal peptide synthetases (NRPSs) are large multidomain proteins that catalyze the formation of a wide range of biologically active natural products. These megasynthetases contain condensation (C) domains that catalyze peptide bond formation and chain elongation. The natural substrates for C domains are biosynthetic intermediates that are covalently tethered to thiolation (T) domains within the synthetase by thioester linkages. Characterizing C domain substrate specificity is important for the engineered biosynthesis of new compounds. RESULTS We synthesized a series of aminoacyl-N-acetylcysteamine thioesters (aminoacyl-SNACs) and show that they are small-molecule substrates for NRPS C domains. Comparison of rates of peptide bond formation catalyzed by the C domain from enterobactin synthetase with various aminoacyl-SNACs as downstream (acceptor) substrates revealed high selectivity for the natural substrate analog L-Ser-SNAC. Comparing L- and D-Phe-SNACs as upstream (donor) substrates for the first C domain from tyrocidine synthetase revealed clear D- versus L-selectivity. CONCLUSIONS Aminoacyl-SNACs are substrates for NRPS C domains and are useful for characterizing the substrate specificity of C domain-catalyzed peptide bond formation.
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Affiliation(s)
- D E Ehmann
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
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Ehmann DE, Shaw-Reid CA, Losey HC, Walsh CT. The EntF and EntE adenylation domains of Escherichia coli enterobactin synthetase: sequestration and selectivity in acyl-AMP transfers to thiolation domain cosubstrates. Proc Natl Acad Sci U S A 2000; 97:2509-14. [PMID: 10688898 PMCID: PMC15959 DOI: 10.1073/pnas.040572897] [Citation(s) in RCA: 88] [Impact Index Per Article: 3.7] [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: 11/18/2022] Open
Abstract
Enterobactin, the tris-(N-(2,3-dihydroxybenzoyl)serine) trilactone siderophore of Escherichia coli, is synthesized by a three-protein (EntE, B, F) six-module nonribosomal peptide synthetase (NRPS). In this work, the 142-kDa four-domain protein EntF was bisected into two double-domain fragments: a 108-kDa condensation and adenylation construct, EntF C-A, and a 37-kDa peptidyl carrier protein (PCP) and thioesterase protein, EntF PCP-TE. The adenylation domain activity of EntF C-A formed seryl-AMP but lost the ability to transfer the seryl moiety to the cognate EntF PCP-TE in trans. Seryl transfer to heterologous PCP protein fragments, the SrfB1 PCP from surfactin synthetase and Ybt PCP1 from yersiniabactin synthetase, was observed at rates of 0.5 min(-1) and 0.01 min(-1), respectively. The possibility that these slow acylation rates reflected dissociation of acyl/aminoacyl-AMP followed by adventitious thiolation by the heterologous PCPs in solution was addressed by measuring catalytic turnover of pyrophosphate (PP(i)) released from the adenylation domain. The holo SrfB1 PCP protein as well as Ybt PCP1 did not stimulate an increase in PP(i) release from EntF C-A or EntE. In this light, aminoacylations in trans between A and PCP domain fragments of NRPS assembly lines must be subjected to kinetic scrutiny to determine whether transfer is truly between protein domains or results from slow aminoacyl-AMP release and subsequent nonenzymatic thiol capture.
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Affiliation(s)
- D E Ehmann
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
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Keating TA, Suo Z, Ehmann DE, Walsh CT. Selectivity of the yersiniabactin synthetase adenylation domain in the two-step process of amino acid activation and transfer to a holo-carrier protein domain. Biochemistry 2000; 39:2297-306. [PMID: 10694396 DOI: 10.1021/bi992341z] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.5] [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: 11/29/2022]
Abstract
The adenylation (A) domain of the Yersinia pestis nonribosomal peptide synthetase that biosynthesizes the siderophore yersiniabactin (Ybt) activates three molecules of L-cysteine and covalently aminoacylates the phosphopantetheinyl (P-pant) thiols on three peptidyl carrier protein (PCP) domains embedded in the two synthetase subunits, two in cis (PCP1, PCP2) in subunit HMWP2 and one in trans (PCP3) in subunit HMWP1. This two-step process of activation and loading by the A domain is analogous to the operation of the aminoacyl-tRNA synthetases in ribosomal peptide synthesis. Adenylation domain specificity for the first step of reversible aminoacyl adenylate formation was assessed with the amino acid-dependent [(32)P]-PP(i)-ATP exchange assay to show that S-2-aminobutyrate and beta-chloro-L-alanine were alternate substrates. The second step of A domain catalysis, capture of the bound aminoacyl adenylate by the P-pant-SH of the PCP domains, was assayed both by catalytic release of PP(i) and by covalent aminoacylation of radiolabeled substrates on either the PCP1 fragment of HMWP2 or the PCP3-thioesterase double domain fragment of HMWP1. There was little selectivity for capture of each of the three adenylates by PCP3 in the second step, arguing against any hydrolytic proofreading of incorrect substrates by the A domain. The holo-PCP3 domain accelerated PP(i) release and catalytic turnover by 100-200-fold over the leak rate (<1 min(-1)) of aminoacyl adenylates into solution while PCP1 in trans had only about a 5-fold effect. Free pantetheine could capture cysteinyl adenylate with a 25-50-fold increase in k(cat) while CoA was 10-fold less effective. The K(m) of free pantetheine (30-50 mM) was 3 orders of magnitude larger than that of PCP3-TE (10-25 microM), indicating a net 10(4) greater catalytic efficiency for transfer to the P-pant arm of PCP3 by the Ybt synthetase A domain, relative to P-pant alone.
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Affiliation(s)
- T A Keating
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115, USA
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Ehmann DE, Gehring AM, Walsh CT. Lysine biosynthesis in Saccharomyces cerevisiae: mechanism of alpha-aminoadipate reductase (Lys2) involves posttranslational phosphopantetheinylation by Lys5. Biochemistry 1999; 38:6171-7. [PMID: 10320345 DOI: 10.1021/bi9829940] [Citation(s) in RCA: 134] [Impact Index Per Article: 5.4] [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: 11/30/2022]
Abstract
A key step in fungal biosynthesis of lysine, enzymatic reduction of alpha-aminoadipate at C6 to the semialdehyde, requires two gene products in Saccharomyces cerevisiae, Lys2 and Lys5. Here, we show that the 31-kDa Lys5 is a specific posttranslational modification catalyst, using coenzyme A (CoASH) as a cosubstrate to phosphopantetheinylate Ser880 of the 155-kDa Lys2 and activate it for catalysis. Lys2 was subcloned from S. cerevisiae and expressed in and purified from Escherichia coli as a full-length 155-kDa enzyme, as a 105-kDa adenylation/peptidyl carrier protein (A/PCP) fragment (residues 1-924), and as a 14-kDa PCP fragment (residues 809-924). The apo-PCP fragment was covalently modified to phosphopantetheinylated holo-PCP by pure Lys5 and CoASH with a Km of 1 microM and kcat of 3 min-1 for both the PCP and CoASH substrates. The adenylation domain of the A/PCP fragment activated S-carboxymethyl-L-cysteine (kcat/Km = 840 mM-1 min-1) at 16% the efficiency of L-alpha-aminoadipate in [32P]PPi/ATP exchange assays. The holo form of the A/PCP 105-kDa fragment of Lys2 covalently aminoacylated itself with [35S]S-carboxymethyl-L-cysteine. Addition of NADPH discharged the covalent acyl-S-PCP Lys2, consistent with a reductive cleavage of the acyl-S-enzyme intermediate. These results identify the Lys5/Lys2 pair as a two-component system in which Lys5 covalently primes Lys2, allowing alpha-aminoadipate reductase activity by holo-Lys2 with catalytic cycles of autoaminoacylation and reductive cleavage. This is a novel mechanism for a fungal enzyme essential for amino acid metabolism.
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Affiliation(s)
- D E Ehmann
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115, USA
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Bebout DC, DeLanoy AE, Ehmann DE, Kastner ME, Parrish DA, Butcher RJ. Characterization of Mercury(II) Complexes of Bis[(2-pyridyl)methyl]amine by X-ray Crystallography and NMR Spectroscopy. Inorg Chem 1998. [DOI: 10.1021/ic971499+] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Bebout DC, Ehmann DE, Trinidad JC, Crahan KK, Kastner ME, Parrish DA. Preparation of Mercury(II) Complexes of Tris[(2-pyridyl)methyl]amine and Characterization by X-ray Crystallography and NMR Spectroscopy. Inorg Chem 1997. [DOI: 10.1021/ic9702779] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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