1
|
Blake KS, Kumar H, Loganathan A, Williford EE, Diorio-Toth L, Xue YP, Tang WK, Campbell TP, Chong DD, Angtuaco S, Wencewicz TA, Tolia NH, Dantas G. Sequence-structure-function characterization of the emerging tetracycline destructase family of antibiotic resistance enzymes. Commun Biol 2024; 7:336. [PMID: 38493211 PMCID: PMC10944477 DOI: 10.1038/s42003-024-06023-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [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: 10/10/2023] [Accepted: 03/07/2024] [Indexed: 03/18/2024] Open
Abstract
Tetracycline destructases (TDases) are flavin monooxygenases which can confer resistance to all generations of tetracycline antibiotics. The recent increase in the number and diversity of reported TDase sequences enables a deep investigation of the TDase sequence-structure-function landscape. Here, we evaluate the sequence determinants of TDase function through two complementary approaches: (1) constructing profile hidden Markov models to predict new TDases, and (2) using multiple sequence alignments to identify conserved positions important to protein function. Using the HMM-based approach we screened 50 high-scoring candidate sequences in Escherichia coli, leading to the discovery of 13 new TDases. The X-ray crystal structures of two new enzymes from Legionella species were determined, and the ability of anhydrotetracycline to inhibit their tetracycline-inactivating activity was confirmed. Using the MSA-based approach we identified 31 amino acid positions 100% conserved across all known TDase sequences. The roles of these positions were analyzed by alanine-scanning mutagenesis in two TDases, to study the impact on cell and in vitro activity, structure, and stability. These results expand the diversity of TDase sequences and provide valuable insights into the roles of important residues in TDases, and flavin monooxygenases more broadly.
Collapse
Affiliation(s)
- Kevin S Blake
- The Edison Family Center for Genome Sciences and Systems Biology, Washington University School of Medicine, St. Louis, MO, USA
| | - Hirdesh Kumar
- Host-Pathogen Interactions and Structural Vaccinology section (HPISV), National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health (NIH), Bethesda, MD, USA
| | - Anisha Loganathan
- The Edison Family Center for Genome Sciences and Systems Biology, Washington University School of Medicine, St. Louis, MO, USA
| | - Emily E Williford
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO, USA
| | - Luke Diorio-Toth
- The Edison Family Center for Genome Sciences and Systems Biology, Washington University School of Medicine, St. Louis, MO, USA
| | - Yao-Peng Xue
- The Edison Family Center for Genome Sciences and Systems Biology, Washington University School of Medicine, St. Louis, MO, USA
| | - Wai Kwan Tang
- Host-Pathogen Interactions and Structural Vaccinology section (HPISV), National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health (NIH), Bethesda, MD, USA
| | - Tayte P Campbell
- The Edison Family Center for Genome Sciences and Systems Biology, Washington University School of Medicine, St. Louis, MO, USA
| | - David D Chong
- The Edison Family Center for Genome Sciences and Systems Biology, Washington University School of Medicine, St. Louis, MO, USA
| | - Steven Angtuaco
- The Edison Family Center for Genome Sciences and Systems Biology, Washington University School of Medicine, St. Louis, MO, USA
| | - Timothy A Wencewicz
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO, USA.
| | - Niraj H Tolia
- Host-Pathogen Interactions and Structural Vaccinology section (HPISV), National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health (NIH), Bethesda, MD, USA.
| | - Gautam Dantas
- The Edison Family Center for Genome Sciences and Systems Biology, Washington University School of Medicine, St. Louis, MO, USA.
- Department of Pathology and Immunology, Division of Laboratory and Genomic Medicine, Washington University School of Medicine, St. Louis, MO, USA.
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO, USA.
- Department of Biomedical Engineering, Washington University School of Medicine, St. Louis, MO, USA.
- Department of Pediatrics, Washington University School of Medicine, St. Louis, MO, USA.
| |
Collapse
|
2
|
Abstract
Desferrioxamine siderophores are assembled by the nonribosomal-peptide-synthetase-independent siderophore (NIS) synthetase enzyme DesD via ATP-dependent iterative condensation of three N1-hydroxy-N1-succinyl-cadaverine (HSC) units. Current knowledge of NIS enzymology and the desferrioxamine biosynthetic pathway does not account for the existence of most known members of this natural product family, which differ in substitution patterns of the N- and C-termini. The directionality of desferrioxamine biosynthetic assembly, N-to-C versus C-to-N, is a longstanding knowledge gap that is limiting further progress in understanding the origins of natural products in this structural family. Here, we establish the directionality of desferrioxamine biosynthesis using a chemoenzymatic approach with stable isotope incorporation and dimeric substrates. We propose a mechanism where DesD catalyzes the N-to-C condensation of HSC units to establish a unifying biosynthetic paradigm for desferrioxamine natural products in Streptomyces.
Collapse
Affiliation(s)
- Jinping Yang
- Department of Chemistry, Washington University in St. Louis, One Brookings Drive, St. Louis, Missouri 63130, United States
| | - Victoria S Banas
- Department of Chemistry, Washington University in St. Louis, One Brookings Drive, St. Louis, Missouri 63130, United States
| | - Gerry S M Rivera
- Department of Chemistry, Washington University in St. Louis, One Brookings Drive, St. Louis, Missouri 63130, United States
| | - Timothy A Wencewicz
- Department of Chemistry, Washington University in St. Louis, One Brookings Drive, St. Louis, Missouri 63130, United States
| |
Collapse
|
3
|
Kumar H, Williford EE, Blake KS, Virgin-Downey B, Dantas G, Wencewicz TA, Tolia NH. Publisher Correction: Structure of anhydrotetracycline-bound Tet(X6) reveals the mechanism for inhibition of type 1 tetracycline destructases. Commun Biol 2023; 6:506. [PMID: 37169854 PMCID: PMC10175298 DOI: 10.1038/s42003-023-04906-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/13/2023] Open
Affiliation(s)
- Hirdesh Kumar
- Host-pathogen interaction and structural vaccinology section (HPISV), National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health (NIH), Bethesda, MD, USA
| | - Emily E Williford
- Department of Chemistry, Washington University in St. Louis, One Brookings Drive, St. Louis, MO, 63130, USA
| | - Kevin S Blake
- The Edison Family Center for Genome Sciences and Systems Biology, Washington University School of Medicine, St. Louis, MO, USA
| | - Brett Virgin-Downey
- Department of Chemistry, Washington University in St. Louis, One Brookings Drive, St. Louis, MO, 63130, USA
| | - Gautam Dantas
- The Edison Family Center for Genome Sciences and Systems Biology, Washington University School of Medicine, St. Louis, MO, USA.
- Department of Pathology and Immunology, Division of Laboratory and Genomic Medicine, Washington University School of Medicine, St. Louis, MO, USA.
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO, USA.
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO, USA.
- Department of Pediatrics, Washington University School of Medicine, St. Louis, MO, USA.
| | - Timothy A Wencewicz
- Department of Chemistry, Washington University in St. Louis, One Brookings Drive, St. Louis, MO, 63130, USA.
| | - Niraj H Tolia
- Host-pathogen interaction and structural vaccinology section (HPISV), National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health (NIH), Bethesda, MD, USA.
| |
Collapse
|
4
|
Kumar H, Williford EE, Blake KS, Virgin-Downey B, Dantas G, Wencewicz TA, Tolia NH. Structure of anhydrotetracycline-bound Tet(X6) reveals the mechanism for inhibition of type 1 tetracycline destructases. Commun Biol 2023; 6:423. [PMID: 37062778 PMCID: PMC10106456 DOI: 10.1038/s42003-023-04792-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [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: 07/22/2022] [Accepted: 03/31/2023] [Indexed: 04/18/2023] Open
Abstract
Inactivation of tetracycline antibiotics by tetracycline destructases (TDases) remains a clinical and agricultural threat. TDases can be classified as type 1 Tet(X)-like TDases and type 2 soil-derived TDases. Type 1 TDases are widely identified in clinical pathogens. A combination therapy of tetracycline and a TDase inhibitor is much needed to rescue the clinical efficacy of tetracyclines. Anhydrotetracycline is a pan-TDase inhibitor that inhibits both type 1 and type 2 TDases. Here, we present structural, biochemical, and phenotypic evidence that anhydrotetracycline binds in a substrate-like orientation and competitively inhibits the type 1 TDase Tet(X6) to rescue tetracycline antibiotic activity as a sacrificial substrate. Anhydrotetracycline interacting residues of Tet(X6) are conserved within type 1 TDases, indicating a conserved binding mode and mechanism of inhibition. This mode of binding and inhibition is distinct from anhydrotetracycline's inhibition of type 2 TDases. This study forms the framework for development of next-generation therapies to counteract enzymatic tetracycline resistance.
Collapse
Affiliation(s)
- Hirdesh Kumar
- Host-pathogen interaction and structural vaccinology section (HPISV), National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health (NIH), Bethesda, MD, USA
| | - Emily E Williford
- Department of Chemistry, Washington University in St. Louis, One Brookings Drive, St. Louis, MO, 63130, USA
| | - Kevin S Blake
- The Edison Family Center for Genome Sciences and Systems Biology, Washington University School of Medicine, St. Louis, MO, USA
| | - Brett Virgin-Downey
- Department of Chemistry, Washington University in St. Louis, One Brookings Drive, St. Louis, MO, 63130, USA
| | - Gautam Dantas
- The Edison Family Center for Genome Sciences and Systems Biology, Washington University School of Medicine, St. Louis, MO, USA.
- Department of Pathology and Immunology, Division of Laboratory and Genomic Medicine, Washington University School of Medicine, St. Louis, MO, USA.
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO, USA.
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO, USA.
- Department of Pediatrics, Washington University School of Medicine, St. Louis, MO, USA.
| | - Timothy A Wencewicz
- Department of Chemistry, Washington University in St. Louis, One Brookings Drive, St. Louis, MO, 63130, USA.
| | - Niraj H Tolia
- Host-pathogen interaction and structural vaccinology section (HPISV), National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health (NIH), Bethesda, MD, USA.
| |
Collapse
|
5
|
Williford EE, DeAngelo CM, Blake KS, Kumar H, Lam KK, Jones KV, Tolia NH, Dantas G, Wencewicz TA. Structure-Based Design of Bisubstrate Tetracycline Destructase Inhibitors That Block Flavin Redox Cycling. J Med Chem 2023; 66:3917-3933. [PMID: 36877173 PMCID: PMC10099279 DOI: 10.1021/acs.jmedchem.2c01629] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [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: 03/07/2023]
Abstract
Tetracyclines (TCs) are an important class of antibiotics threatened by an emerging new resistance mechanism─enzymatic inactivation. These TC-inactivating enzymes, also known as tetracycline destructases (TDases), inactivate all known TC antibiotics, including drugs of last resort. Combination therapies consisting of a TDase inhibitor and a TC antibiotic represent an attractive strategy for overcoming this type of antibiotic resistance. Here, we report the structure-based design, synthesis, and evaluation of bifunctional TDase inhibitors derived from anhydrotetracycline (aTC). By appending a nicotinamide isostere to the C9 position of the aTC D-ring, we generated bisubstrate TDase inhibitors. The bisubstrate inhibitors have extended interactions with TDases by spanning both the TC and presumed NADPH binding pockets. This simultaneously blocks TC binding and the reduction of FAD by NADPH while "locking" TDases in an unproductive FAD "out" conformation.
Collapse
Affiliation(s)
- Emily E. Williford
- Department of Chemistry, Washington University in St. Louis, One Brookings Drive, St. Louis, MO, 63130, USA
| | - Caitlin M. DeAngelo
- Department of Chemistry, Washington University in St. Louis, One Brookings Drive, St. Louis, MO, 63130, USA
| | - Kevin S. Blake
- The Edison Family Center for Genome Sciences and Systems Biology, Washington University School of Medicine, 4513 Clayton Ave., St. Louis, MO, 63108, USA
| | - Hirdesh Kumar
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institute of Health, 9000 Rockville Pike, BG 29B Rm 4NN08, Bethesda, MD, 20814, USA
| | - Kendrick K. Lam
- Department of Chemistry, Washington University in St. Louis, One Brookings Drive, St. Louis, MO, 63130, USA
| | - Katherine V. Jones
- Department of Chemistry, Washington University in St. Louis, One Brookings Drive, St. Louis, MO, 63130, USA
| | - Niraj H. Tolia
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institute of Health, 9000 Rockville Pike, BG 29B Rm 4NN08, Bethesda, MD, 20814, USA
| | - Gautam Dantas
- The Edison Family Center for Genome Sciences and Systems Biology, Washington University School of Medicine, 4513 Clayton Ave., St. Louis, MO, 63108, USA
- Department of Pathology and Immunology, Washington University School of Medicine, 660 S. Euclid Ave., St. Louis, MO, 63110, USA
- Department of Molecular Microbiology, Washington University School of Medicine, 4515 McKinley Ave., St. Louis, MO, 63110, USA
- Department of Biomedical Engineering, Washington University in St. Louis, One Brookings Drive, St. Louis, MO, 63130, USA
| | - Timothy A. Wencewicz
- Department of Chemistry, Washington University in St. Louis, One Brookings Drive, St. Louis, MO, 63130, USA
| |
Collapse
|
6
|
Abstract
Siderophores produced via nonribosomal peptide synthetase (NRPS) pathways serve as critical virulence factors for many pathogenic bacteria. Improved knowledge of siderophore biosynthesis guides the development of inhibitors, vaccines, and other therapeutic strategies. Fimsbactin A is a mixed ligand siderophore derived from human pathogenic Acinetobacter baumannii that contains phenolate-oxazoline, catechol, and hydroxamate metal chelating groups branching from a central l-Ser tetrahedral unit via amide and ester linkages. Fimsbactin A is derived from two molecules of l-Ser, two molecules of 2,3-dihydroxybenzoic acid (DHB), and one molecule of l-Orn and is a product of the fbs biosynthetic operon. Here, we report the complete in vitro reconstitution of fimsbactin A biosynthesis in a cell-free system using purified enzymes. We demonstrate the conversion of l-Orn to N1-acetyl-N1-hydroxy-putrescine (ahPutr) via ordered action of FbsJ (decarboxylase), FbsI (flavin N-monooxygenase), and FbsK (N-acetyltransferase). We achieve conversion of l-Ser, DHB, and l-Orn to fimsbactin A using FbsIJK in combination with the NRPS modules FbsEFGH. We also demonstrate chemoenzymatic conversion of synthetic ahPutr to fimsbactin A using FbsEFGH and establish the substrate selectivity for the NRPS adenylation domains in FbsH (DHB) and FbsF (l-Ser). We assign a role for the type II thioesterase FbsM in producing the shunt metabolite 2-(2,3-dihydroxyphenyl)-4,5-dihydrooxazole-4-carboxylic acid (DHB-oxa) via cleavage of the corresponding thioester intermediate that is tethered to NRPS peptidyl carrier domains during biosynthetic assembly. We propose a mechanism for branching NRPS-derived peptides via amide and ester linkages via the dynamic equilibration of N-DHB-Ser and O-DHB-Ser thioester intermediates via hydrolysis of DHB-oxa thioester intermediates. We also propose a genetic signature for NRPS "branching" in the presence of a terminating C-T-C motif (FbsG).
Collapse
Affiliation(s)
- Jinping Yang
- Department of Chemistry, Washington University in St. Louis, One Brookings Drive, St. Louis, Missouri 63130, United States
| | - Timothy A Wencewicz
- Department of Chemistry, Washington University in St. Louis, One Brookings Drive, St. Louis, Missouri 63130, United States
| |
Collapse
|
7
|
Yang J, Banas VS, Patel KD, Rivera GSM, Mydy LS, Gulick AM, Wencewicz TA. An acyl-adenylate mimic reveals the structural basis for substrate recognition by the iterative siderophore synthetase DesD. J Biol Chem 2022; 298:102166. [PMID: 35750210 PMCID: PMC9356276 DOI: 10.1016/j.jbc.2022.102166] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [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: 04/12/2022] [Revised: 06/13/2022] [Accepted: 06/16/2022] [Indexed: 11/18/2022] Open
Abstract
Siderophores are conditionally essential metabolites used by microbes for environmental iron sequestration. Most Streptomyces strains produce hydroxamate-based desferrioxamine (DFO) siderophores composed of repeating units of N1-hydroxy-cadaverine (or N1-hydroxy-putrescine) and succinate. The DFO biosynthetic operon, desABCD, is highly conserved in Streptomyces; however, expression of desABCD alone does not account for the vast structural diversity within this natural product class. Here, we report the in vitro reconstitution and biochemical characterization of four DesD orthologs from Streptomyces strains that produce unique DFO siderophores. Under in vitro conditions, all four DesD orthologs displayed similar saturation steady-state kinetics (Vmax = 0.9–2.5 μM⋅min−1) and produced the macrocyclic trimer DFOE as the favored product, suggesting a conserved role for DesD in the biosynthesis of DFO siderophores. We further synthesized a structural mimic of N1-hydroxy-N1-succinyl-cadaverine (HSC)-acyl-adenylate, the HSC-acyl sulfamoyl adenosine analog (HSC-AMS), and obtained crystal structures of DesD in the ATP-bound, AMP/PPi-bound, and HSC-AMS/Pi-bound forms. We found HSC-AMS inhibited DesD orthologs (IC50 values = 48–53 μM) leading to accumulation of linear trimeric DFOG and di-HSC at the expense of macrocyclic DFOE. Addition of exogenous PPi enhanced DesD inhibition by HSC-AMS, presumably via stabilization of the DesD–HSC-AMS complex, similar to the proposed mode of adenylate stabilization where PPi remains buried in the active site. In conclusion, our data suggest that acyl-AMS derivatives may have utility as chemical probes and bisubstrate inhibitors to reveal valuable mechanistic and structural insight for this unique family of adenylating enzymes.
Collapse
Affiliation(s)
- Jinping Yang
- Department of Chemistry, Washington University in St Louis, St Louis, Missouri, USA
| | - Victoria S Banas
- Department of Chemistry, Washington University in St Louis, St Louis, Missouri, USA
| | - Ketan D Patel
- Department of Structural Biology, Jacobs School of Medicine & Biomedical Sciences at the University at Buffalo, Buffalo, New York, USA
| | - Gerry S M Rivera
- Department of Chemistry, Washington University in St Louis, St Louis, Missouri, USA
| | - Lisa S Mydy
- Department of Structural Biology, Jacobs School of Medicine & Biomedical Sciences at the University at Buffalo, Buffalo, New York, USA
| | - Andrew M Gulick
- Department of Structural Biology, Jacobs School of Medicine & Biomedical Sciences at the University at Buffalo, Buffalo, New York, USA.
| | - Timothy A Wencewicz
- Department of Chemistry, Washington University in St Louis, St Louis, Missouri, USA.
| |
Collapse
|
8
|
Yang J, Qi Y, Blodgett JAV, Wencewicz TA. Multifunctional P450 Monooxygenase CftA Diversifies the Clifednamide Pool through Tandem C-H Bond Activations. J Nat Prod 2022; 85:47-55. [PMID: 35086337 DOI: 10.1021/acs.jnatprod.1c00606] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Polycyclic tetramate macrolactams (PTMs) are a class of structurally complex hybrid polyketide-nonribosomal peptide (PK-NRP) natural products produced by diverse bacteria. Several PTMs display pharmaceutically interesting bioactivities, and the early stages of PTM biosynthesis involving polyketide synthase (PKS) and nonribosomal peptide synthetase (NRPS) enzymology are well studied. However, the timing and mechanisms of post PKS-NRPS oxidations by P450 monooxygenases encoded in PTM biosynthetic gene clusters (BGCs) remain poorly characterized. Here we demonstrate that CftA, encoded in clifednamide-type PTM BGCs, is a multifunctional P450 monooxygenase capable of converting the C29-C30 ethyl side chain of ikarugamycin to either a C29-C30 methyl ketone or a C29-C30 hydroxymethyl ketone through C-H bond activation, resulting in the formation of clifednamide A or clifednamide C, respectively. We also report the complete structure of clifednamide C solved via multidimensional NMR (COSY, HSQC, HMBC, NOESY, and TOCSY) using material purified from an engineered Streptomyces strain optimized for production. Finally, the in vitro reconstitution of recombinant CftA catalytic activity revealed the oxidation cascade for sequential conversion of ikarugamycin to clifednamide A and clifednamide C. Our findings confirm prior genetics-based predictions on the origins of clifednamide complexity via P450s encoded in PTM BGCs and place CftA into a growing group of multifunctional P450s that tailor PTM natural products through late-stage regioselective C-H bond activation.
Collapse
Affiliation(s)
- Jinping Yang
- Department of Chemistry, Washington University in St. Louis, One Brookings Drive, St. Louis, Missouri 63130, United States
| | - Yunci Qi
- Department of Biology, Washington University in St. Louis, One Brookings Drive, St. Louis, Missouri 63130, United States
| | - Joshua A V Blodgett
- Department of Biology, Washington University in St. Louis, One Brookings Drive, St. Louis, Missouri 63130, United States
| | - Timothy A Wencewicz
- Department of Chemistry, Washington University in St. Louis, One Brookings Drive, St. Louis, Missouri 63130, United States
| |
Collapse
|
9
|
Bohac TJ, Fang L, Banas VS, Giblin DE, Wencewicz TA. Synthetic Mimics of Native Siderophores Disrupt Iron Trafficking in Acinetobacter baumannii. ACS Infect Dis 2021; 7:2138-2151. [PMID: 34110766 DOI: 10.1021/acsinfecdis.1c00119] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [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: 01/14/2023]
Abstract
Many pathogenic bacteria biosynthesize and excrete small molecule metallophores, known as siderophores, that are used to extract ferric iron from host sources to satisfy nutritional need. Native siderophores are often structurally complex multidentate chelators that selectively form high-affinity octahedral ferric iron complexes with defined chirality recognizable by cognate protein receptors displayed on the bacterial cell surface. Simplified achiral analogues can serve as synthetically tractable siderophore mimics with potential utility as chemical probes and therapeutic agents to better understand and treat bacterial infections, respectively. Here, we demonstrate that synthetic spermidine-derived mixed ligand bis-catecholate monohydroxamate siderophores (compounds 1-3) are versatile structural and biomimetic analogues of two native siderophores, acinetobactin and fimsbactin, produced by Acinetobacter baumannii, a multidrug-resistant Gram-negative human pathogen. The metal-free and ferric iron complexes of the synthetic siderophores are growth-promoting agents of A. baumannii, while the Ga(III)-complexes are potent growth inhibitors of A. baumannii with MIC values <1 μM. The synthetic siderophores compete with native siderophores for uptake in A. baumannii and maintain comparable apparent binding affinities for ferric iron (KFe) and the siderophore-binding protein BauB (Kd). Our findings provide new insight to guide the structural fine-tuning of these compounds as siderophore-based therapeutics targeting pathogenic strains of A. baumannii.
Collapse
Affiliation(s)
- Tabbetha J. Bohac
- Department of Chemistry, Washington University in St. Louis, One Brookings Drive, St. Louis, Missouri 63130, United States
| | - Luting Fang
- Department of Chemistry, Washington University in St. Louis, One Brookings Drive, St. Louis, Missouri 63130, United States
| | - Victoria S. Banas
- Department of Chemistry, Washington University in St. Louis, One Brookings Drive, St. Louis, Missouri 63130, United States
| | - Daryl E. Giblin
- Department of Chemistry, Washington University in St. Louis, One Brookings Drive, St. Louis, Missouri 63130, United States
| | - Timothy A. Wencewicz
- Department of Chemistry, Washington University in St. Louis, One Brookings Drive, St. Louis, Missouri 63130, United States
| |
Collapse
|
10
|
Valentino H, Korasick DA, Bohac TJ, Shapiro JA, Wencewicz TA, Tanner JJ, Sobrado P. Structural and Biochemical Characterization of the Flavin-Dependent Siderophore-Interacting Protein from Acinetobacter baumannii. ACS Omega 2021; 6:18537-18547. [PMID: 34308084 PMCID: PMC8296543 DOI: 10.1021/acsomega.1c03047] [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] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Accepted: 06/23/2021] [Indexed: 05/09/2023]
Abstract
Acinetobacter baumannii is an opportunistic pathogen with a high mortality rate due to multi-drug-resistant strains. The synthesis and uptake of the iron-chelating siderophores acinetobactin (Acb) and preacinetobactin (pre-Acb) have been shown to be essential for virulence. Here, we report the kinetic and structural characterization of BauF, a flavin-dependent siderophore-interacting protein (SIP) required for the reduction of Fe(III) bound to Acb/pre-Acb and release of Fe(II). Stopped-flow spectrophotometric studies of the reductive half-reaction show that BauF forms a stable neutral flavin semiquinone intermediate. Reduction with NAD(P)H is very slow (k obs, 0.001 s-1) and commensurate with the rate of reduction by photobleaching, suggesting that NAD(P)H are not the physiological partners of BauF. The reduced BauF was oxidized by Acb-Fe (k obs, 0.02 s-1) and oxazole pre-Acb-Fe (ox-pre-Acb-Fe) (k obs, 0.08 s-1), a rigid analogue of pre-Acb, at a rate 3-11 times faster than that with molecular oxygen alone. The structure of FAD-bound BauF was solved at 2.85 Å and was found to share a similarity to Shewanella SIPs. The biochemical and structural data presented here validate the role of BauF in A. baumannii iron assimilation and provide information important for drug design.
Collapse
Affiliation(s)
- Hannah Valentino
- Department
of Biochemistry, Virginia Tech, Blacksburg, Virginia 24061, United States
| | - David A. Korasick
- Department
of Biochemistry, University of Missouri, Columbia, Missouri 65211, United States
| | - Tabbetha J. Bohac
- Department
of Chemistry, Washington University in Saint
Louis, St. Louis, Missouri 63130, United States
| | - Justin A. Shapiro
- Department
of Chemistry, Washington University in Saint
Louis, St. Louis, Missouri 63130, United States
| | - Timothy A. Wencewicz
- Department
of Chemistry, Washington University in Saint
Louis, St. Louis, Missouri 63130, United States
| | - John J. Tanner
- Department
of Biochemistry, University of Missouri, Columbia, Missouri 65211, United States
- Department
of Chemistry, University of Missouri, Columbia, Missouri 65211, United States
| | - Pablo Sobrado
- Department
of Biochemistry, Virginia Tech, Blacksburg, Virginia 24061, United States
| |
Collapse
|
11
|
Gasparrini AJ, Markley JL, Kumar H, Wang B, Fang L, Irum S, Symister CT, Wallace M, Burnham CAD, Andleeb S, Tolia NH, Wencewicz TA, Dantas G. Tetracycline-inactivating enzymes from environmental, human commensal, and pathogenic bacteria cause broad-spectrum tetracycline resistance. Commun Biol 2020; 3:241. [PMID: 32415166 PMCID: PMC7229144 DOI: 10.1038/s42003-020-0966-5] [Citation(s) in RCA: 83] [Impact Index Per Article: 20.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2019] [Accepted: 04/17/2020] [Indexed: 12/19/2022] Open
Abstract
Tetracycline resistance by antibiotic inactivation was first identified in commensal organisms but has since been reported in environmental and pathogenic microbes. Here, we identify and characterize an expanded pool of tet(X)-like genes in environmental and human commensal metagenomes via inactivation by antibiotic selection of metagenomic libraries. These genes formed two distinct clades according to habitat of origin, and resistance phenotypes were similarly correlated. Each gene isolated from the human gut encodes resistance to all tetracyclines tested, including eravacycline and omadacycline. We report a biochemical and structural characterization of one enzyme, Tet(X7). Further, we identify Tet(X7) in a clinical Pseudomonas aeruginosa isolate and demonstrate its contribution to tetracycline resistance. Lastly, we show anhydrotetracycline and semi-synthetic analogues inhibit Tet(X7) to prevent enzymatic tetracycline degradation and increase tetracycline efficacy against strains expressing tet(X7). This work improves our understanding of resistance by tetracycline-inactivation and provides the foundation for an inhibition-based strategy for countering resistance.
Collapse
Affiliation(s)
- Andrew J Gasparrini
- The Edison Family Center for Genome Sciences & Systems Biology, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Jana L Markley
- Department of Chemistry, Washington University, St. Louis, MO, 63130, USA
| | - Hirdesh Kumar
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO, 63110, USA.,Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Bin Wang
- The Edison Family Center for Genome Sciences & Systems Biology, Washington University School of Medicine, St. Louis, MO, 63110, USA.,Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Luting Fang
- Department of Chemistry, Washington University, St. Louis, MO, 63130, USA
| | - Sidra Irum
- The Edison Family Center for Genome Sciences & Systems Biology, Washington University School of Medicine, St. Louis, MO, 63110, USA.,Atta ur Rahman School of Applied Biosciences, National University of Sciences and Technology, Islamabad, Pakistan
| | - Chanez T Symister
- Department of Chemistry, Washington University, St. Louis, MO, 63130, USA
| | - Meghan Wallace
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Carey-Ann D Burnham
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO, 63110, USA.,Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO, 63110, USA.,Department of Pediatrics, Washington University School of Medicine, St. Louis, MO, 63110, USA.,Department of Medicine, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Saadia Andleeb
- Atta ur Rahman School of Applied Biosciences, National University of Sciences and Technology, Islamabad, Pakistan
| | - Niraj H Tolia
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO, 63110, USA. .,Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA.
| | | | - Gautam Dantas
- The Edison Family Center for Genome Sciences & Systems Biology, Washington University School of Medicine, St. Louis, MO, 63110, USA. .,Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO, 63110, USA. .,Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO, 63110, USA. .,Department of Biomedical Engineering, Washington University, St. Louis, MO, 63130, USA.
| |
Collapse
|
12
|
Endicott N, Rivera GSM, Yang J, Wencewicz TA. Emergence of Ferrichelatase Activity in a Siderophore-Binding Protein Supports an Iron Shuttle in Bacteria. ACS Cent Sci 2020; 6:493-506. [PMID: 32341999 PMCID: PMC7181320 DOI: 10.1021/acscentsci.9b01257] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Indexed: 05/08/2023]
Abstract
Siderophores are small-molecule high-affinity multidentate chelators selective for ferric iron that are produced by pathogenic microbes to aid in nutrient sequestration and enhance virulence. In Gram-positive bacteria, the currently accepted paradigm in siderophore-mediated iron acquisition is that effluxed metal-free siderophores extract ferric iron from biological sources and the resulting ferric siderophore complex undergoes diffusion-controlled association with a surface-displayed siderophore-binding protein (SBP) followed by ABC permease-mediated translocation across the cell envelope powered by ATP hydrolysis. Here we show that a more efficient paradigm is possible in Gram-positive bacteria where extracellular metal-free siderophores associate directly with apo-SBPs on the cell surface and serve as non-covalent cofactors that enable the holo-SBPs to non-reductively extract ferric iron directly from host metalloproteins with so-called "ferrichelatase" activity. The resulting SBP-bound ferric siderophore complex is ready for import through an associated membrane permease and enzymatic turnover is achieved through cofactor replacement from the readily available pool of extracellular siderophores. This new "iron shuttle" model closes a major knowledge gap in microbial iron acquisition and defines new roles of the siderophore and SBP as cofactor and enzyme, respectively, in addition to the classically accepted roles as a transport substrate and receptor pair. We propose the formal name "siderophore-dependent ferrichelatases" for this new class of catalytic SBPs.
Collapse
|
13
|
Abstract
The biosynthesis of antibiotics and self-protection mechanisms employed by antibiotic producers are an integral part of the growing antibiotic resistance threat. The origins of clinically relevant antibiotic resistance genes found in human pathogens have been traced to ancient microbial producers of antibiotics in natural environments. Widespread and frequent antibiotic use amplifies environmental pools of antibiotic resistance genes and increases the likelihood for the selection of a resistance event in human pathogens. This perspective will provide an overview of the origins of antibiotic resistance to highlight the crossroads of antibiotic biosynthesis and producer self-protection that result in clinically relevant resistance mechanisms. Some case studies of synergistic antibiotic combinations, adjuvants, and hybrid antibiotics will also be presented to show how native antibiotic producers manage the emergence of antibiotic resistance.
Collapse
Affiliation(s)
- Timothy A Wencewicz
- Department of Chemistry, Washington University in St. Louis, One Brookings Drive, St. Louis, MO 63130, USA.
| |
Collapse
|
14
|
Bohac TJ, Fang L, Giblin DE, Wencewicz TA. Fimsbactin and Acinetobactin Compete for the Periplasmic Siderophore Binding Protein BauB in Pathogenic Acinetobacter baumannii. ACS Chem Biol 2019; 14:674-687. [PMID: 30785725 DOI: 10.1021/acschembio.8b01051] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Environmental and pathogenic microbes produce siderophores as small iron-binding molecules to scavenge iron from natural environments. It is common for microbes to produce multiple siderophores to gain a competitive edge in mixed microbial environments. Strains of human pathogenic Acinetobacter baumannii produce up to three siderophores: acinetobactin, baumannoferrin, and fimsbactin. Production of acinetobactin and baumannoferrin is highly conserved among clinical isolates while fimsbactin production appears to be less common. Fimsbactin is structurally related to acinetobactin through the presence of catecholate and phenolate oxazoline metal-binding motifs, and both are derived from nonribosomal peptide assembly lines with similar catalytic domain orientations and identities. Here we report on the chemical, biochemical, and microbiological investigation of fimsbactin and acinetobactin alone and in combination. We show that fimsbactin forms a 1:1 complex with iron(III) that is thermodynamically more stable than the 2:1 acinetobactin ferric complex. Alone, both acinetobactin and fimsbactin stimulate A. baumannii growth, but in combination the two siderophores appear to compete and collectively inhibit bacterial growth. We show that fimsbactin directly competes with acinetobactin for binding the periplasmic siderophore-binding protein BauB suggesting a possible biochemical mechanism for the phenomenon where the buildup of apo-siderophores in the periplasm leads to iron starvation. We propose an updated model for siderophore utilization and competition in A. baumannii that frames the molecular, biochemical, and cellular interplay of multiple iron acquisition systems in a multidrug resistant Gram-negative human pathogen.
Collapse
Affiliation(s)
- Tabbetha J. Bohac
- Department of Chemistry, Washington University in St. Louis, One Brookings Drive, St. Louis, Missouri 63130, United States
| | - Luting Fang
- Department of Chemistry, Washington University in St. Louis, One Brookings Drive, St. Louis, Missouri 63130, United States
| | - Daryl E. Giblin
- Department of Chemistry, Washington University in St. Louis, One Brookings Drive, St. Louis, Missouri 63130, United States
| | - Timothy A. Wencewicz
- Department of Chemistry, Washington University in St. Louis, One Brookings Drive, St. Louis, Missouri 63130, United States
| |
Collapse
|
15
|
Markley JL, Fang L, Gasparrini AJ, Symister CT, Kumar H, Tolia NH, Dantas G, Wencewicz TA. Semisynthetic Analogues of Anhydrotetracycline as Inhibitors of Tetracycline Destructase Enzymes. ACS Infect Dis 2019; 5:618-633. [PMID: 30835428 DOI: 10.1021/acsinfecdis.8b00349] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The synthesis and biological evaluation of semisynthetic anhydrotetracycline analogues as small molecule inhibitors of tetracycline-inactivating enzymes are reported. Inhibitor potency was found to vary as a function of enzyme (major) and substrate-inhibitor pair (minor), and anhydrotetracycline analogue stability to enzymatic and nonenzymatic degradation in solution contributes to their ability to rescue tetracycline activity in whole cell Escherichia coli expressing tetracycline destructase enzymes. Taken collectively, these results provide the framework for the rational design of next-generation inhibitor libraries en route to a viable and proactive adjuvant approach to combat the enzymatic degradation of tetracycline antibiotics.
Collapse
Affiliation(s)
| | | | - Andrew J. Gasparrini
- The Edison Family Center for Genome Sciences & Systems Biology, Washington University School of Medicine, 4513 Clayton Ave., Campus Box 8510, St. Louis, Missouri 63108, United States
| | | | - Hirdesh Kumar
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 9000 Rockville Pike, BG 29B Rm 4NN08, Bethesda, Maryland 20814, United States
| | - Niraj H. Tolia
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 9000 Rockville Pike, BG 29B Rm 4NN08, Bethesda, Maryland 20814, United States
| | - Gautam Dantas
- The Edison Family Center for Genome Sciences & Systems Biology, Washington University School of Medicine, 4513 Clayton Ave., Campus Box 8510, St. Louis, Missouri 63108, United States
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, Missouri 63110, United States
- Department of Molecular Microbiology, Washington University School of Medicine, 4515 McKinley Avenue, fifth Floor, Room 5314, St. Louis, Missouri 63110, United States
| | | |
Collapse
|
16
|
Bailey DC, Bohac TJ, Shapiro JA, Giblin DE, Wencewicz TA, Gulick AM. Crystal Structure of the Siderophore Binding Protein BauB Bound to an Unusual 2:1 Complex Between Acinetobactin and Ferric Iron. Biochemistry 2018; 57:6653-6661. [PMID: 30406986 DOI: 10.1021/acs.biochem.8b00986] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The critical role that iron plays in many biochemical processes has led to an elaborate battle between bacterial pathogens and their hosts to acquire and withhold this critical nutrient. Exploitation of iron nutritional immunity is being increasingly appreciated as a potential antivirulence therapeutic strategy, especially against problematic multidrug resistant Gram-negative pathogens such as Acinetobacter baumannii. To facilitate iron uptake and promote growth, A. baumannii produces a nonribosomally synthesized peptide siderophore called acinetobactin. Acinetobactin is unusual in that it is first biosynthesized in an oxazoline form called preacinetobactin that spontaneously isomerizes to the final isoxazolidinone acinetobactin. Interestingly, both isomers can bind iron and both support growth of A. baumannii. To address how the two isomers chelate their ferric cargo and how the complexes are used by A. baumannii, structural studies were carried out with the ferric acinetobactin complex and its periplasmic siderophore binding protein BauB. Herein, we present the crystal structure of BauB bound to a bis-tridentate (Fe3+L2) siderophore complex. Additionally, we present binding studies that show multiple variants of acinetobactin bind BauB with no apparent change in affinity. These results are consistent with the structural model that depicts few direct polar interactions between BauB and the acinetobactin backbone. This structural and functional characterization of acinetobactin and its requisite binding protein BauB provides insight that could be exploited to target this critical iron acquisition system and provide a novel approach to treat infections caused by this important multidrug resistant pathogen.
Collapse
Affiliation(s)
- Daniel C Bailey
- Department of Structural Biology , Jacobs School of Medicine & Biomedical Sciences at the University at Buffalo , 955 Main Street , Buffalo , New York 14203 , United States
| | - Tabbetha J Bohac
- Department of Chemistry , Washington University in St. Louis , One Brookings Drive , St. Louis , Missouri 63130 , United States
| | - Justin A Shapiro
- Department of Chemistry , Washington University in St. Louis , One Brookings Drive , St. Louis , Missouri 63130 , United States
| | - Daryl E Giblin
- Department of Chemistry , Washington University in St. Louis , One Brookings Drive , St. Louis , Missouri 63130 , United States
| | - Timothy A Wencewicz
- Department of Chemistry , Washington University in St. Louis , One Brookings Drive , St. Louis , Missouri 63130 , United States
| | - Andrew M Gulick
- Department of Structural Biology , Jacobs School of Medicine & Biomedical Sciences at the University at Buffalo , 955 Main Street , Buffalo , New York 14203 , United States
| |
Collapse
|
17
|
Abstract
Tetracyclines have been foundational antibacterial agents for more than 70 years. Renewed interest in tetracycline antibiotics is being driven by advancements in tetracycline synthesis and strategic scaffold modifications designed to overcome established clinical resistance mechanisms including efflux and ribosome protection. Emerging new resistance mechanisms, including enzymatic antibiotic inactivation, threaten recent progress on bringing these next-generation tetracyclines to the clinic. Here we review the current state of knowledge on the structure, mechanism, and inhibition of tetracycline-inactivating enzymes.
Collapse
Affiliation(s)
- Jana L Markley
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO, United States
| | - Timothy A Wencewicz
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO, United States
| |
Collapse
|
18
|
Rivera GSM, Beamish CR, Wencewicz TA. Immobilized FhuD2 Siderophore-Binding Protein Enables Purification of Salmycin Sideromycins from Streptomyces violaceus DSM 8286. ACS Infect Dis 2018; 4:845-859. [PMID: 29460625 DOI: 10.1021/acsinfecdis.8b00015] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [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: 12/22/2022]
Abstract
Siderophores are a structurally diverse class of natural products common to most bacteria and fungi as iron(III)-chelating ligands. Siderophores, including trihydroxamate ferrioxamines, are used clinically to treat iron overload diseases and show promising activity against many other iron-related human diseases. Here, we present a new method for the isolation of ferrioxamine siderophores from complex mixtures using affinity chromatography based on resin-immobilized FhuD2, a siderophore-binding protein (SBP) from Staphylococcus aureus. The SBP-resin enabled purification of charge positive, charge negative, and neutral ferrioxamine siderophores. Treatment of culture supernatants from Streptomyces violaceus DSM 8286 with SBP-resin provided an analytically pure sample of the salmycins, a mixture of structurally complex glycosylated sideromycins (siderophore-antibiotic conjugates) with potent antibacterial activity toward human pathogenic Staphylococcus aureus (minimum inhibitory concentration (MIC) = 7 nM). Siderophore affinity chromatography could enable the rapid discovery of new siderophore and sideromycin natural products from complex mixtures to aid drug discovery and metabolite identification efforts in a broad range of therapeutic areas.
Collapse
Affiliation(s)
- Gerry Sann M. Rivera
- Department of Chemistry, Washington University in St. Louis, One Brookings Drive, St. Louis, Missouri 63130, United States
| | - Catherine R. Beamish
- Department of Chemistry, Washington University in St. Louis, One Brookings Drive, St. Louis, Missouri 63130, United States
| | - Timothy A. Wencewicz
- Department of Chemistry, Washington University in St. Louis, One Brookings Drive, St. Louis, Missouri 63130, United States
| |
Collapse
|
19
|
Markley JL, Morse TL, Rath NP, Wencewicz TA. Stream-lined synthesis of 3-hydroxy-β-lactams: Norrish-Yang type II photocyclizations of β-ketoformamides. Tetrahedron 2018. [DOI: 10.1016/j.tet.2018.04.040] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
|
20
|
Patrick GJ, Fang L, Schaefer J, Singh S, Bowman GR, Wencewicz TA. Mechanistic Basis for ATP-Dependent Inhibition of Glutamine Synthetase by Tabtoxinine-β-lactam. Biochemistry 2018; 57:117-135. [PMID: 29039929 PMCID: PMC5934995 DOI: 10.1021/acs.biochem.7b00838] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [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] [Indexed: 02/04/2023]
Abstract
Tabtoxinine-β-lactam (TβL), also known as wildfire toxin, is a time- and ATP-dependent inhibitor of glutamine synthetase produced by plant pathogenic strains of Pseudomonas syringae. Here we demonstrate that recombinant glutamine synthetase from Escherichia coli phosphorylates the C3-hydroxyl group of the TβL 3-(S)-hydroxy-β-lactam (3-HβL) warhead. Phosphorylation of TβL generates a stable, noncovalent enzyme-ADP-inhibitor complex that resembles the glutamine synthetase tetrahedral transition state. The TβL β-lactam ring remains intact during enzyme inhibition, making TβL mechanistically distinct from traditional β-lactam antibiotics such as penicillin. Our findings could enable the design of new 3-HβL transition state inhibitors targeting enzymes in the ATP-dependent carboxylate-amine ligase superfamily with broad therapeutic potential in many disease areas.
Collapse
Affiliation(s)
- Garrett J. Patrick
- Department of Chemistry, Washington University in St. Louis, One Brookings Drive, St. Louis, MO, 63130, USA
| | - Luting Fang
- Department of Chemistry, Washington University in St. Louis, One Brookings Drive, St. Louis, MO, 63130, USA
| | - Jacob Schaefer
- Department of Chemistry, Washington University in St. Louis, One Brookings Drive, St. Louis, MO, 63130, USA
| | - Sukrit Singh
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, 660 South Euclid Avenue, St. Louis, MO, 63110, USA
| | - Gregory R. Bowman
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, 660 South Euclid Avenue, St. Louis, MO, 63110, USA
| | - Timothy A. Wencewicz
- Department of Chemistry, Washington University in St. Louis, One Brookings Drive, St. Louis, MO, 63130, USA
| |
Collapse
|
21
|
Abstract
The emergence of multidrug resistant (MDR) Gram-negative bacterial pathogens has raised global concern. Nontraditional therapeutic strategies, including antivirulence approaches, are gaining traction as a means of applying less selective pressure for resistance in vivo. Here, we show that rigidifying the structure of the siderophore preacinetobactin from MDR Acinetobacter baumannii via oxidation of the phenolate-oxazoline moiety to a phenolate-oxazole results in a potent inhibitor of siderophore transport and imparts a bacteriostatic effect at low micromolar concentrations under infection-like conditions.
Collapse
Affiliation(s)
- Tabbetha J. Bohac
- Department of Chemistry, Washington University in St. Louis, One Brookings Drive, St. Louis, Missouri 63130, United States
| | - Justin A. Shapiro
- Department of Chemistry, Washington University in St. Louis, One Brookings Drive, St. Louis, Missouri 63130, United States
| | - Timothy A. Wencewicz
- Department of Chemistry, Washington University in St. Louis, One Brookings Drive, St. Louis, Missouri 63130, United States
| |
Collapse
|
22
|
Abstract
Staphylococcus aureus produces a cocktail of metallophores (staphylopine, staphyloferrin A, and staphyloferrin B) to scavenge transition metals during infection of a host. In addition, S. aureus displays the extracellular surface lipoproteins FhuD1 and FhuD2 along with the ABC transporter complex FhuCBG to facilitate the use of hydroxamate xenosiderophores such as desferrioxamine B (DFOB) for iron acquisition. DFOB is used as a chelation therapy to treat human iron overload diseases and has been linked to an increased risk of S. aureus infections. We used a panel of synthetic DFOB analogs and a FhuD2-selective trihydroxamate sideromycin to probe xenosiderophore utilization in S. aureus and establish structure-activity relationships for Fe(III) binding, FhuD2 binding, S. aureus growth promotion, and competition for S. aureus cell entry. Fe(III) binding assays and FhuD2 intrinsic fluorescence quenching experiments revealed that diverse chemical modifications of the terminal ends of linear ferrioxamine siderophores influences Fe(III) affinity but not FhuD2 binding. Siderophore-sideromycin competition assays and xenosiderophore growth promotion assays revealed that S. aureus SG511 and ATCC 11632 can distinguish between competing siderophores based exclusively on net charge of the siderophore-Fe(III) complex. Our work provides a roadmap for tuning hydroxamate xenosiderophore scaffolds to suppress (net negative charge) or enhance (net positive or neutral charge) uptake by S. aureus for applications in metal chelation therapy and siderophore-mediated antibiotic delivery, respectively.
Collapse
Affiliation(s)
- Nathaniel P. Endicott
- Department of Chemistry, Washington University in St. Louis, One Brookings Drive, St. Louis, Missouri 63130, United States
| | - Eries Lee
- Department of Chemistry, Washington University in St. Louis, One Brookings Drive, St. Louis, Missouri 63130, United States
| | - Timothy A. Wencewicz
- Department of Chemistry, Washington University in St. Louis, One Brookings Drive, St. Louis, Missouri 63130, United States
| |
Collapse
|
23
|
Park J, Gasparrini AJ, Reck MR, Symister CT, Elliott JL, Vogel JP, Wencewicz TA, Dantas G, Tolia NH. Plasticity, dynamics, and inhibition of emerging tetracycline resistance enzymes. Nat Chem Biol 2017; 13:730-736. [PMID: 28481346 PMCID: PMC5478473 DOI: 10.1038/nchembio.2376] [Citation(s) in RCA: 68] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Accepted: 02/08/2017] [Indexed: 12/18/2022]
Abstract
While tetracyclines are an important class of antibiotics in agriculture and the clinic, their efficacy is threatened by increasing resistance. Resistance to tetracyclines can occur through efflux, ribosomal protection, or enzymatic inactivation. Surprisingly, tetracycline enzymatic inactivation has remained largely unexplored despite providing the distinct advantage of antibiotic clearance. The tetracycline destructases are a recently-discovered family of tetracycline-inactivating flavoenzymes from pathogens and soil metagenomes with a high potential for broad dissemination. Here, we show tetracycline destructases accommodate tetracycline-class antibiotics in diverse and novel orientations for catalysis, and antibiotic binding drives unprecedented structural dynamics facilitating tetracycline inactivation. We identify a key inhibitor binding mode that locks the flavin adenine dinucleotide cofactor in an inactive state, functionally rescuing tetracycline activity. Our results reveal the potential of a novel tetracycline/tetracycline destructase inhibitor combination therapy strategy to overcome resistance by enzymatic inactivation and restore the use of an important class of antibiotics.
Collapse
Affiliation(s)
- Jooyoung Park
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Andrew J Gasparrini
- Center for Genome Sciences and Systems Biology, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Margaret R Reck
- Department of Chemistry, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Chanez T Symister
- Department of Chemistry, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Jennifer L Elliott
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Joseph P Vogel
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Timothy A Wencewicz
- Department of Chemistry, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Gautam Dantas
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri, USA.,Center for Genome Sciences and Systems Biology, Washington University School of Medicine, St. Louis, Missouri, USA.,Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, Missouri, USA.,Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Niraj H Tolia
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri, USA.,Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri, USA
| |
Collapse
|
24
|
|
25
|
Shapiro JA, Wencewicz TA. Acinetobactin Isomerization Enables Adaptive Iron Acquisition in Acinetobacter baumannii through pH-Triggered Siderophore Swapping. ACS Infect Dis 2016; 2:157-68. [PMID: 27624967 DOI: 10.1021/acsinfecdis.5b00145] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [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: 01/27/2023]
Abstract
Pathogenic strains of Acinetobacter baumannii excrete multiple siderophores that enhance iron scavenging from host sources. The oxazoline siderophore pre-acinetobactin undergoes an unusual non-enzymatic isomerization, producing the isoxazolidinone acinetobactin. In this study, we explored the kinetics, mechanism, and biological consequence of this siderophore swapping. Pre-acinetobactin is excreted to the extracellular space where the isomerization to acinetobactin occurs with a pH-rate profile consistent with 5-exo-tet cyclization at C5' with clean stereochemical inversion. Pre-acinetobactin persists at pH <6, and acinetobactin is rapidly formed at pH >7, matching each siderophore's pH preference for iron(III) chelation and A. baumannii growth promotion. Acinetobactin isomerization provides two siderophores for the price of one, enabling A. baumannii to sequester iron over a broad pH range likely to be encountered during the course of an infection.
Collapse
Affiliation(s)
- Justin A. Shapiro
- Department of Chemistry, Washington University in St. Louis, One Brookings Drive, St. Louis, Missouri 63130, United States
| | - Timothy A. Wencewicz
- Department of Chemistry, Washington University in St. Louis, One Brookings Drive, St. Louis, Missouri 63130, United States
| |
Collapse
|
26
|
Hart KM, Reck M, Bowman GR, Wencewicz TA. Tabtoxinine-β-lactam is a “stealth” β-lactam antibiotic that evades β-lactamase-mediated antibiotic resistance. Med Chem Commun 2016. [DOI: 10.1039/c5md00325c] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Tabtoxinine-β-lactam (TβL) is a phytotoxin produced by plant pathogenic strains of Pseudomonas syringae.
Collapse
Affiliation(s)
- Kathryn M. Hart
- Department of Biochemistry and Molecular Biophysics
- Washington University School of Medicine
- St. Louis
- USA
| | - Margaret Reck
- Department of Chemistry
- Washington University in St. Louis
- St. Louis
- USA
| | - Gregory R. Bowman
- Department of Biochemistry and Molecular Biophysics
- Washington University School of Medicine
- St. Louis
- USA
| | | |
Collapse
|
27
|
Gelman SJ, Mahieu NG, Cho K, Llufrio EM, Wencewicz TA, Patti GJ. Evidence that 2-hydroxyglutarate is not readily metabolized in colorectal carcinoma cells. Cancer Metab 2015; 3:13. [PMID: 26629338 PMCID: PMC4665876 DOI: 10.1186/s40170-015-0139-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [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: 08/21/2015] [Accepted: 11/09/2015] [Indexed: 12/13/2022] Open
Abstract
Background Two-hydroxyglutarate (2HG) is present at low concentrations in healthy mammalian cells as both an L and D enantiomer. Both the L and D enantiomers have been implicated in regulating cellular physiology by mechanisms that are only partially characterized. In multiple human cancers, the D enantiomer accumulates due to gain-of-function mutations in the enzyme isocitrate dehydrogenase (IDH) and has been hypothesized to drive malignancy through mechanisms that remain incompletely understood. While much attention has been dedicated to identifying the route of 2HG synthesis, the metabolic fate of 2HG has not been studied in detail. Yet the metabolism of 2HG may have important mechanistic consequences influencing cell function and cancer pathogenesis, such as modulating redox potential or producing unknown products with unique modes of action. Results By applying our isotope-based metabolomic platform, we unbiasedly and comprehensively screened for products of L- and D-2HG in HCT116 colorectal carcinoma cells harboring a mutation in IDH1. After incubating HCT116 cells in uniformly 13C-labeled 2HG for 24 h, we used liquid chromatography/mass spectrometry to track the labeled carbons in small molecules. Strikingly, we did not identify any products of 2HG metabolism from the thousands of metabolomic features that we screened. Consistent with these results, we did not detect any significant changes in the labeling patterns of tricarboxylic acid cycle metabolites from wild type or IDH1 mutant cells cultured in 13C-labeled glucose upon the addition of L, D, or racemic mixtures of 2HG. A more sensitive, targeted analysis revealed trace levels of isotopic enrichment (<1 %) in some central carbon metabolites from 13C-labeled 2HG. However, we found that cells do not deplete 2HG from the media at levels above our detection limit over a 48 h time period. Conclusions Taken together, we conclude that 2HG carbon is not readily transformed in the HCT116 cell line. These data indicate that the phenotypic alterations induced by 2HG are not a result of its metabolic products.
Collapse
Affiliation(s)
- Susan J Gelman
- Department of Chemistry, Washington University, St. Louis, MO 63130 USA ; Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110 USA
| | - Nathaniel G Mahieu
- Department of Chemistry, Washington University, St. Louis, MO 63130 USA ; Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110 USA
| | - Kevin Cho
- Department of Chemistry, Washington University, St. Louis, MO 63130 USA ; Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110 USA
| | - Elizabeth M Llufrio
- Department of Chemistry, Washington University, St. Louis, MO 63130 USA ; Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110 USA
| | | | - Gary J Patti
- Department of Chemistry, Washington University, St. Louis, MO 63130 USA ; Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110 USA
| |
Collapse
|
28
|
Forsberg KJ, Patel S, Wencewicz TA, Dantas G. The Tetracycline Destructases: A Novel Family of Tetracycline-Inactivating Enzymes. ACTA ACUST UNITED AC 2015; 22:888-97. [PMID: 26097034 DOI: 10.1016/j.chembiol.2015.05.017] [Citation(s) in RCA: 109] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2015] [Revised: 05/05/2015] [Accepted: 05/17/2015] [Indexed: 10/23/2022]
Abstract
Enzymes capable of inactivating tetracycline are paradoxically rare compared with enzymes that inactivate other natural-product antibiotics. We describe a family of flavoenzymes, previously unrecognizable as resistance genes, which are capable of degrading tetracycline antibiotics. From soil functional metagenomic selections, we discovered nine genes that confer high-level tetracycline resistance by enzymatic inactivation. We also demonstrate that a tenth enzyme, an uncharacterized homolog in the human pathogen Legionella longbeachae, similarly inactivates tetracycline. These enzymes catalyze the oxidation of tetracyclines in vitro both by known mechanisms and via previously undescribed activity. Tetracycline-inactivation genes were identified in diverse soil types, encompass substantial sequence diversity, and are adjacent to genes implicated in horizontal gene transfer. Because tetracycline inactivation is scarcely observed in hospitals, these enzymes may fill an empty niche in pathogenic organisms, and should therefore be monitored for their dissemination potential into the clinic.
Collapse
Affiliation(s)
- Kevin J Forsberg
- Center for Genome Sciences & Systems Biology, Washington University School of Medicine, St. Louis, MO 63108, USA
| | - Sanket Patel
- Center for Genome Sciences & Systems Biology, Washington University School of Medicine, St. Louis, MO 63108, USA; Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO 63108, USA
| | - Timothy A Wencewicz
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63130, USA.
| | - Gautam Dantas
- Center for Genome Sciences & Systems Biology, Washington University School of Medicine, St. Louis, MO 63108, USA; Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO 63108, USA; Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO 63130, USA.
| |
Collapse
|
29
|
Walsh CT, Wencewicz TA. Prospects for new antibiotics: a molecule-centered perspective. J Antibiot (Tokyo) 2013; 67:7-22. [DOI: 10.1038/ja.2013.49] [Citation(s) in RCA: 272] [Impact Index Per Article: 24.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2013] [Revised: 04/22/2013] [Accepted: 05/01/2013] [Indexed: 12/12/2022]
|
30
|
Wencewicz TA, Miller MJ. Biscatecholate-monohydroxamate mixed ligand siderophore-carbacephalosporin conjugates are selective sideromycin antibiotics that target Acinetobacter baumannii. J Med Chem 2013; 56:4044-52. [PMID: 23614627 DOI: 10.1021/jm400265k] [Citation(s) in RCA: 95] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Chemical syntheses and biological evaluation of biscatecholate-monohydroxamate mixed ligand sideromycins utilizing the carbacephalosporin β-lactam antibiotic loracarbef and the fluoroquinolone antibiotic ciprofloxacin are described. The mixed ligand β-lactam sideromycin (1b) had remarkably selective and extremely potent antibacterial activity against the Gram-negative pathogen Acinetobacter baumannii ATCC 17961 (MIC = 0.0078 μM). The antibacterial activity of the β-lactam sideromycin was inversely related to the iron(III) concentration in the testing media and was antagonized by the presence of the competing parent siderophore. These data suggested that active transport of the mixed ligand β-lactam sideromycin across the outer cell membrane of A. baumannii via siderophore-uptake pathways was responsible for the selective and potent antibacterial activity.
Collapse
Affiliation(s)
- Timothy A Wencewicz
- Department of Chemistry and Biochemistry, University of Notre Dame, 251 Nieuwland Science Hall, Notre Dame, Indiana 46556, USA
| | | |
Collapse
|
31
|
Wencewicz TA, Long TE, Möllmann U, Miller MJ. Trihydroxamate siderophore-fluoroquinolone conjugates are selective sideromycin antibiotics that target Staphylococcus aureus. Bioconjug Chem 2013; 24:473-86. [PMID: 23350642 DOI: 10.1021/bc300610f] [Citation(s) in RCA: 96] [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: 11/28/2022]
Abstract
Siderophores are multidentate iron(III) chelators used by bacteria for iron assimilation. Sideromycins, also called siderophore-antibiotic conjugates, are a unique subset of siderophores that enter bacterial cells via siderophore uptake pathways and deliver the toxic antibiotic in a "Trojan horse" fashion. Sideromycins represent a novel antibiotic delivery technology with untapped potential for developing sophisticated microbe-selective antibacterial agents that limit the emergence of bacterial resistance. The chemical synthesis of a series of mono-, bis-, and trihydroxamate sideromycins are described here along with their biological evaluation in antibacterial susceptibility assays. The linear hydroxamate siderophores used for the sideromycins in this study were derived from the ferrioxamine family and inspired by the naturally occurring salmycin sideromycins. The antibacterial agents used were a β-lactam carbacepholosporin, Lorabid, and a fluoroquinolone, ciprofloxacin, chosen for the different locations of their biological targets, the periplasm (extracellular) and the cytoplasm (intracellular). The linear hydroxamate-based sideromycins were selectively toxic toward Gram-positive bacteria, especially Staphylococcus aureus SG511 (MIC = 1.0 μM for the trihydroxamate-fluoroquinolone sideromycin). Siderophore-sideromycin competition assays demonstrated that only the fluoroquinolone sideromycins required membrane transport to reach their cytoplasmic biological target and that a trihydroxamate siderophore backbone was required for protein-mediated active transport of the sideromycins into S. aureus cells via siderophore uptake pathways. This work represents a comprehensive study of linear hydroxamate sideromycins and teaches how to build effective hydroxamate-based sideromycins as Gram-positive selective antibiotic agents.
Collapse
Affiliation(s)
- Timothy A Wencewicz
- Department of Chemistry and Biochemistry, 251 Nieuwland Science Hall, University of Notre Dame, Notre Dame, IN 46556, USA
| | | | | | | |
Collapse
|
32
|
Abstract
Riboflavin-based coenzymes, tightly bound to enzymes catalyzing substrate oxidations and reductions, enable an enormous range of chemical transformations in biosynthetic pathways. Flavoenzymes catalyze substrate oxidations involving amine and alcohol oxidations and desaturations to olefins, the latter setting up Diels-Alder cyclizations in lovastatin and solanapyrone biosyntheses. Both C(4a) and N(5) of the flavin coenzymes are sites for covalent adduct formation. For example, the reactivity of dihydroflavins with molecular oxygen leads to flavin-4a-OOH adducts which then carry out a diverse range of oxygen transfers, including Baeyer-Villiger type ring expansions, olefin epoxidations, halogenations via transient HOCl generation, and an oxidative Favorskii rerrangement during enterocin assembly.
Collapse
Affiliation(s)
- Christopher T Walsh
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, 240 Longwood Ave., Boston, MA 02115, USA.
| | | |
Collapse
|
33
|
Abstract
Plant pathogenic Pseudomonas syringae produce the hydroxy-β-lactam antimetabolite tabtoxinine-β-lactam (TβL) as a time-dependent inactivating glutamine analogue of plant glutamine synthetases. The producing pseudomonads use multiple modes of self-protection, two of which are characterized in this study. The first is the dipeptide ligase TblF which converts tabtoxinine-β-lactam to the TβL-Thr dipeptide known as tabtoxin. The dipeptide is not recognized by glutamine synthetase. This represents a Trojan Horse strategy: the dipeptide is secreted, taken up by dipeptide permeases in neighboring cells, and TβL is released by peptidase action. The second self-protection mode is elaboration by the acetyltransferase Ttr, which acetylates the α-amino group of the proximal inactivator TβL, but not the tabtoxin dipeptide.
Collapse
Affiliation(s)
- Timothy A Wencewicz
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115, United States
| | | |
Collapse
|
34
|
Abstract
A method was developed to synthesize macrocyclic trihydroxamate siderophores using optimized Yamaguchi macrolactonization conditions. The natural ability of siderophores to bind iron(III) was exploited to template the reactions and allowed for rapid reaction rates, high product conversions, and the formation of large macrolactone rings up to 35 atoms. An X-ray structure of a 33-membered macrolactone siderophore-Fe(III) complex is presented.
Collapse
Affiliation(s)
- Timothy A Wencewicz
- Department of Chemistry and Biochemistry, University of Notre Dame, 251 Nieuwland Science Hall, Notre Dame, Indiana 46556, USA
| | | | | |
Collapse
|
35
|
Wencewicz TA, Yang B, Rudloff JR, Oliver AG, Miller MJ. N-O chemistry for antibiotics: discovery of N-alkyl-N-(pyridin-2-yl)hydroxylamine scaffolds as selective antibacterial agents using nitroso Diels-Alder and ene chemistry. J Med Chem 2011; 54:6843-58. [PMID: 21859126 PMCID: PMC3188665 DOI: 10.1021/jm200794r] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [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: 11/28/2022]
Abstract
The discovery, syntheses, and structure-activity relationships (SAR) of a new family of heterocyclic antibacterial compounds based on N-alkyl-N-(pyridin-2-yl)hydroxylamine scaffolds are described. A structurally diverse library of ∼100 heterocyclic molecules generated from Lewis acid-mediated nucleophilic ring-opening reactions with nitroso Diels-Alder cycloadducts and nitroso ene reactions with substituted alkenes was evaluated in whole cell antibacterial assays. Compounds containing the N-alkyl-N-(pyridin-2-yl)hydroxylamine structure demonstrated selective and potent antibacterial activity against the Gram-positive bacterium Micrococcus luteus ATCC 10240 (MIC(90) = 2.0 μM or 0.41 μg/mL) and moderate activity against other Gram-positive strains including antibiotic resistant strains of Staphylococcus aureus (MRSA) and Enterococcus faecalis (VRE). A new synthetic route to the active core was developed using palladium-catalyzed Buchwald-Hartwig amination reactions of N-alkyl-O-(4-methoxybenzyl)hydroxylamines with 2-halo-pyridines that facilitated SAR studies and revealed the simplest active structural fragment. This work shows the value of using a combination of diversity-oriented synthesis (DOS) and parallel synthesis for identifying new antibacterial scaffolds.
Collapse
Affiliation(s)
- Timothy A. Wencewicz
- Department of Chemistry and Biochemistry, 251 Nieuwland Science Hall, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Baiyuan Yang
- Department of Chemistry and Biochemistry, 251 Nieuwland Science Hall, University of Notre Dame, Notre Dame, IN 46556, USA
| | - James R. Rudloff
- Department of Chemistry and Biochemistry, 251 Nieuwland Science Hall, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Allen G. Oliver
- Department of Chemistry and Biochemistry, 251 Nieuwland Science Hall, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Marvin J. Miller
- Department of Chemistry and Biochemistry, 251 Nieuwland Science Hall, University of Notre Dame, Notre Dame, IN 46556, USA
| |
Collapse
|
36
|
Mayfield JA, Frederick RE, Streit BR, Wencewicz TA, Ballou DP, DuBois JL. Comprehensive spectroscopic, steady state, and transient kinetic studies of a representative siderophore-associated flavin monooxygenase. J Biol Chem 2010; 285:30375-88. [PMID: 20650894 DOI: 10.1074/jbc.m110.157578] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Many siderophores used for the uptake and intracellular storage of essential iron contain hydroxamate chelating groups. Their biosyntheses are typically initiated by hydroxylation of the primary amine side chains of l-ornithine or l-lysine. This reaction is catalyzed by members of a widespread family of FAD-dependent monooxygenases. Here the kinetic mechanism for a representative family member has been extensively characterized by steady state and transient kinetic methods, using heterologously expressed N(5)-l-ornithine monooxygenase from the pathogenic fungus Aspergillus fumigatus. Spectroscopic data and kinetic analyses suggest a model in which a molecule of hydroxylatable substrate serves as an activator for the reaction of the reduced flavin and O(2). The rate acceleration is only ∼5-fold, a mild effect of substrate on formation of the C4a-hydroperoxide that does not influence the overall rate of turnover. The effect is also observed with the bacterial ornithine monooxygenase PvdA. The C4a-hydroperoxide is stabilized in the absence of hydroxylatable substrate by the presence of bound NADP(+) (t(½) = 33 min, 25 °C, pH 8). NADP(+) therefore is a likely regulator of O(2) and substrate reactivity in the siderophore-associated monooxygenases. Aside from the activating effect of the hydroxylatable substrate, the siderophore-associated monooxygenases share a kinetic mechanism with the hepatic microsomal flavin monooxygenases and bacterial Baeyer-Villiger monooxygenases, with which they share only moderate sequence homology and from which they are distinguished by their acute substrate specificity. The remarkable specificity of the N(5)-l-ornithine monooxygenase-catalyzed reaction suggests added means of reaction control beyond those documented in related well characterized flavoenzymes.
Collapse
Affiliation(s)
- Jeffery A Mayfield
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, USA
| | | | | | | | | | | |
Collapse
|
37
|
Yan S, Miller MJ, Wencewicz TA, Möollmann U. Syntheses and biological evaluation of new cephalosporin-oxazolidinone conjugates. Medchemcomm 2010; 1:145-148. [PMID: 27087912 DOI: 10.1039/c0md00015a] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Two cephalosporin-oxazolidinone conjugates were synthesized by incorporation of a carbamate linker at the 3'-position of the cephalosporin. These compounds show stability in aqueous media until specifically activated by a β-lactamase, and retain antibacterial activities profiles reflecting both the individual cephalosporin and oxazolidinone components.
Collapse
Affiliation(s)
- Shanshan Yan
- Department of Chemistry and Biochemistry, University of Notre Dame, 251 Nieuwland Science Hall, Notre Dame, Indiana, 46556, USA. ; Tel: +1 574 631 7571
| | - Marvin J Miller
- Department of Chemistry and Biochemistry, University of Notre Dame, 251 Nieuwland Science Hall, Notre Dame, Indiana, 46556, USA. ; Tel: +1 574 631 7571
| | - Timothy A Wencewicz
- Department of Chemistry and Biochemistry, University of Notre Dame, 251 Nieuwland Science Hall, Notre Dame, Indiana, 46556, USA. ; Tel: +1 574 631 7571
| | - Ute Möollmann
- Leibniz Institute for Natural Products Research and Infection Biology - Hans Knöell Institute, Beutenbergstrasse 11a, D-07745 Jena, Germany
| |
Collapse
|
38
|
Yan S, Miller MJ, Wencewicz TA, Möllmann U. Syntheses and antibacterial activity studies of new oxazolidinones from nitroso Diels-Alder chemistry. Bioorg Med Chem Lett 2009; 20:1302-5. [PMID: 20031407 DOI: 10.1016/j.bmcl.2009.10.018] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2009] [Revised: 10/02/2009] [Accepted: 10/05/2009] [Indexed: 10/20/2022]
Abstract
A series of novel oxazolidinone antibiotics having [2.2.1] and [2.2.2] bicyclic oxazine moieties at the C-5 side chain of the A-ring was synthesized by nitroso Diels-Alder reactions, from three linezolid analogs containing morpholine, piperazine and thiomorpholine, respectively, as the C-ring components. Subsequent N-O bond cleavage generated oxazolidinones with 4-amino cyclo-2-en-1-ol substituents. The in vitro antibacterial activities of these oxazolidinone analogs were evaluated.
Collapse
Affiliation(s)
- Shanshan Yan
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA
| | | | | | | |
Collapse
|
39
|
Wencewicz TA, Möllmann U, Long TE, Miller MJ. Is drug release necessary for antimicrobial activity of siderophore-drug conjugates? Syntheses and biological studies of the naturally occurring salmycin "Trojan Horse" antibiotics and synthetic desferridanoxamine-antibiotic conjugates. Biometals 2009; 22:633-48. [PMID: 19221879 DOI: 10.1007/s10534-009-9218-3] [Citation(s) in RCA: 94] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2008] [Accepted: 01/27/2009] [Indexed: 11/30/2022]
Abstract
The recent rise in drug resistance found amongst community acquired infections has sparked renewed interest in developing antimicrobial agents that target resistant organisms and limit the natural selection of immune variants. Recent discoveries have shown that iron uptake systems in bacteria and fungi are suitable targets for developing such therapeutic agents. The use of siderophore-drug conjugates as "Trojan Horse" drug delivery agents has attracted particular interest in this area. This review will discuss efforts in our research group to study the salmycin class of "Trojan Horse" antibiotics. Inspired by the natural design of the salmycins, a series of desferridanoxamine-antibiotic conjugates were synthesized and tested in microbial growth inhibition assays. The results of these studies will be related to understanding the role of drug release in siderophore-mediated drug delivery with implications for future siderophore-drug conjugate design.
Collapse
Affiliation(s)
- Timothy A Wencewicz
- Department of Chemistry and Biochemistry, University of Notre Dame, IN 46556, USA
| | | | | | | |
Collapse
|