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Sani MA, Rajput S, Keizer DW, Separovic F. NMR techniques for investigating antimicrobial peptides in model membranes and bacterial cells. Methods 2024; 224:10-20. [PMID: 38295893 DOI: 10.1016/j.ymeth.2024.01.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Revised: 01/07/2024] [Accepted: 01/08/2024] [Indexed: 02/05/2024] Open
Abstract
AMPs are short, mainly cationic membrane-active peptides found in all living organism. They perform diverse roles including signaling and acting as a line of defense against bacterial infections. AMPs have been extensively investigated as templates to facilitate the development of novel antimicrobial therapeutics. Understanding the interplay between these membrane-active peptides and the lipid membranes is considered to be a significant step in elucidating the specific mechanism of action of AMPs against prokaryotic and eukaryotic cells to aid the development of new therapeutics. In this review, we have provided a brief overview of various NMR techniques commonly used for studying AMP structure and AMP-membrane interactions in model membranes and whole cells.
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Affiliation(s)
- Marc-Antoine Sani
- Bio21 Institute, University of Melbourne, Melbourne, VIC 3010, Australia.
| | - Sunnia Rajput
- Bio21 Institute, University of Melbourne, Melbourne, VIC 3010, Australia
| | - David W Keizer
- Bio21 Institute, University of Melbourne, Melbourne, VIC 3010, Australia
| | - Frances Separovic
- Bio21 Institute, University of Melbourne, Melbourne, VIC 3010, Australia; School of Chemistry, University of Melbourne, Melbourne, VIC 3010, Australia
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2
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Rimal B, Chang J, Liu C, Rashid R, Singh M, Kim SJ. The effects of daptomycin on cell wall biosynthesis in Enterococcal faecalis. Sci Rep 2023; 13:12227. [PMID: 37507537 PMCID: PMC10382475 DOI: 10.1038/s41598-023-39486-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2022] [Accepted: 07/26/2023] [Indexed: 07/30/2023] Open
Abstract
Daptomycin is a cyclic lipodepsipeptide antibiotic reserved for the treatment of serious infections by multidrug-resistant Gram-positive pathogens. Its mode of action is considered to be multifaceted, encompassing the targeting and depolarization of bacterial cell membranes, alongside the inhibition of cell wall biosynthesis. To characterize the daptomycin mode of action, 15N cross-polarization at magic-angle spinning NMR measurements were performed on intact whole cells of Staphylococcus aureus grown in the presence of a sub-inhibitory concentration of daptomycin in a chemically defined media containing L-[ϵ-15N]Lys. Daptomycin-treated cells showed a reduction in the lysyl-ε-amide intensity that was consistent with cell wall thinning. However, the reduced lysyl-ε-amine intensity at 10 ppm indicated that the daptomycin-treated cells did not accumulate in Park's nucleotide, the cytoplasmic peptidoglycan (PG) precursor. Consequently, daptomycin did not inhibit the transglycosylation step of PG biosynthesis. To further elucidate the daptomycin mode of action, the PG composition of daptomycin-susceptible Enterococcus faecalis grown in the presence of daptomycin was analyzed using liquid chromatography-mass spectrometry. Sixty-nine muropeptide ions correspond to PG with varying degrees of modifications including crosslinking, acetylation, alanylation, and 1,6-anhydrous ring formation at MurNAc were quantified. Analysis showed that the cell walls of daptomycin-treated E. faecalis had a significant reduction in PG crosslinking which was accompanied by an increase in lytic transglycosylase activities and a decrease in PG-stem modifications by the carboxypeptidases. The changes in PG composition suggest that daptomycin inhibits cell wall biosynthesis by impeding the incorporation of nascent PG into the cell walls by transpeptidases and maturation by carboxypeptidases. As a result, the newly formed cell walls become highly susceptible to degradation by the autolysins, resulting in thinning of the cell wall.
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Affiliation(s)
- Binayak Rimal
- Institute of Biomedical Studies, Baylor University, Waco, TX, 76798, USA
- Division of Infectious Diseases, Johns Hopkins University School of Medicine, Baltimore, MD, 21287, USA
| | - James Chang
- Department of Chemistry One Bear Place #97046, Baylor University, Waco, TX, 76798, USA
| | - Chengyin Liu
- Department of Chemistry, Howard University, Washington, DC, 20059, USA
| | - Raiyan Rashid
- Department of Chemistry, Howard University, Washington, DC, 20059, USA
| | - Manmilan Singh
- Department of Chemistry, Washington University, St. Louis, MO, 63110, USA
| | - Sung Joon Kim
- Department of Chemistry, Howard University, Washington, DC, 20059, USA.
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3
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Werby SH, Brčić J, Chosy MB, Sun J, Rendell JT, Neville LF, Wender PA, Cegelski L. Detection of intact vancomycin-arginine as the active antibacterial conjugate in E. coli by whole-cell solid-state NMR. RSC Med Chem 2023; 14:1192-1198. [PMID: 37360389 PMCID: PMC10285746 DOI: 10.1039/d3md00173c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Accepted: 05/13/2023] [Indexed: 06/28/2023] Open
Abstract
The introduction of new and improved antibacterial agents based on facile synthetic modifications of existing antibiotics represents a promising strategy to deliver urgently needed antibacterial candidates to treat multi-drug resistant bacterial infections. Using this strategy, vancomycin was transformed into a highly active agent against antibiotic-resistant Gram-negative organisms in vitro and in vivo through the addition of a single arginine to yield vancomycin-arginine (V-R). Here, we report detection of the accumulation of V-R in E. coli by whole-cell solid-state NMR using 15N-labeled V-R. 15N CPMAS NMR revealed that the conjugate remained fully amidated without loss of arginine, demonstrating that intact V-R represents the active antibacterial agent. Furthermore, C{N}REDOR NMR in whole cells with all carbons at natural abundance 13C levels exhibited the sensitivity and selectivity to detect the directly bonded 13C-15N pairs of V-R within E. coli cells. Thus, we also present an effective methodology to directly detect and evaluate active drug agents and their accumulation within bacteria without the need for potentially perturbative cell lysis and analysis protocols.
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Affiliation(s)
- Sabrina H Werby
- Department of Chemistry, Stanford University Stanford CA 94305 USA
| | - Jasna Brčić
- Department of Chemistry, Stanford University Stanford CA 94305 USA
| | - Madeline B Chosy
- Department of Chemistry, Stanford University Stanford CA 94305 USA
| | - Jiuzhi Sun
- Department of Chemistry, Stanford University Stanford CA 94305 USA
| | | | | | - Paul A Wender
- Department of Chemistry, Stanford University Stanford CA 94305 USA
- Department of Chemical and Systems Biology, Stanford University Stanford CA 94305 USA
| | - Lynette Cegelski
- Department of Chemistry, Stanford University Stanford CA 94305 USA
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4
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Stojković D, Petrović J, Carević T, Soković M, Liaras K. Synthetic and Semisynthetic Compounds as Antibacterials Targeting Virulence Traits in Resistant Strains: A Narrative Updated Review. Antibiotics (Basel) 2023; 12:963. [PMID: 37370282 PMCID: PMC10295040 DOI: 10.3390/antibiotics12060963] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Revised: 05/24/2023] [Accepted: 05/24/2023] [Indexed: 06/29/2023] Open
Abstract
This narrative review paper provides an up-to-date overview of the potential of novel synthetic and semisynthetic compounds as antibacterials that target virulence traits in resistant strains. The review focused on research conducted in the last five years and investigated a range of compounds including azoles, indoles, thiophenes, glycopeptides, pleuromutilin derivatives, lactone derivatives, and chalcones. The emergence and spread of antibiotic-resistant bacterial strains is a growing public health concern, and new approaches are urgently needed to combat this threat. One promising approach is to target virulence factors, which are essential for bacterial survival and pathogenesis, but not for bacterial growth. By targeting virulence factors, it may be possible to reduce the severity of bacterial infections without promoting the development of resistance. We discuss the mechanisms of action of the various compounds investigated and their potential as antibacterials. The review highlights the potential of targeting virulence factors as a promising strategy to combat antibiotic resistance and suggests that further research is needed to identify new compounds and optimize their efficacy. The findings of this review suggest that novel synthetic and semisynthetic compounds that target virulence factors have great potential as antibacterials in the fight against antibiotic resistance.
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Affiliation(s)
- Dejan Stojković
- Department of Plant Physiology, Institute for Biological Research “Siniša Stanković”—National Institute of the Republic of Serbia, University of Belgrade, Bulevar Despota Stefana 142, 11000 Belgrade, Serbia; (D.S.); (J.P.); (T.C.); (M.S.)
| | - Jovana Petrović
- Department of Plant Physiology, Institute for Biological Research “Siniša Stanković”—National Institute of the Republic of Serbia, University of Belgrade, Bulevar Despota Stefana 142, 11000 Belgrade, Serbia; (D.S.); (J.P.); (T.C.); (M.S.)
| | - Tamara Carević
- Department of Plant Physiology, Institute for Biological Research “Siniša Stanković”—National Institute of the Republic of Serbia, University of Belgrade, Bulevar Despota Stefana 142, 11000 Belgrade, Serbia; (D.S.); (J.P.); (T.C.); (M.S.)
| | - Marina Soković
- Department of Plant Physiology, Institute for Biological Research “Siniša Stanković”—National Institute of the Republic of Serbia, University of Belgrade, Bulevar Despota Stefana 142, 11000 Belgrade, Serbia; (D.S.); (J.P.); (T.C.); (M.S.)
| | - Konstantinos Liaras
- Department of Life and Health Sciences, School of Sciences and Engineering, University of Nicosia, 2417 Nicosia, Cyprus
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5
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Vidal FR, Ossanes DS, Birk L, Scheid C, Barbosa FS, Dallegrave E, Merib J, Eller S, de Oliveira TF. Development and validation of a dried plasma spot LC-MS/MS method for therapeutic monitoring of vancomycin and comparison with enzyme-multiplied immunoassay. Biomed Chromatogr 2023; 37:e5586. [PMID: 36683129 DOI: 10.1002/bmc.5586] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Accepted: 01/17/2023] [Indexed: 01/24/2023]
Abstract
Vancomycin is used as an antimicrobial agent for the treatment of severe gram-positive infections. The importance of therapeutic monitoring of antimicrobials has led to the development of more specific sample preparation techniques capable of identifying with accuracy the concentration of this substance in the organism. An aliquot of 10 μl of plasma was transferred to Whatman 903 paper and dried at room temperature. The extraction method was performed by cutting and transferring the paper to a microtube and adding sodium phosphate buffer and internal standard. The mixture was shaken and centrifuged, and a 5-μl aliquot was injected into the analytical system. The optimization of the main parameters that can influence the extraction efficiency was performed using multivariate approaches to obtain the best conditions. The method developed was validated, providing coefficients of determination higher than 0.994 and a lower limit of quantification of 1 mg/L. Within- and between-run precision ranged from 11.4 to 17.30% and from 6.65 to 13.51%, respectively. This method was successfully applied to 75 samples of patients undergoing vancomycin therapy. The method was rapid, simple, and environmentally friendly with satisfactory analytical performance and was advantageous over the laborious and time-consuming methodologies used in therapeutic drug monitoring routine analyses.
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Affiliation(s)
- Fernanda Ribeiro Vidal
- Graduate Program in Health Sciences, Federal University of Health Sciences of Porto Alegre, Porto Alegre, RS, Brazil
| | - Daniela Souza Ossanes
- Graduate Program in Health Sciences, Federal University of Health Sciences of Porto Alegre, Porto Alegre, RS, Brazil
| | - Letícia Birk
- Graduate Program in Health Sciences, Federal University of Health Sciences of Porto Alegre, Porto Alegre, RS, Brazil
| | - Camila Scheid
- Graduate Program in Health Sciences, Federal University of Health Sciences of Porto Alegre, Porto Alegre, RS, Brazil
| | - Fábio Souza Barbosa
- Graduate Program in Health Sciences, Federal University of Health Sciences of Porto Alegre, Porto Alegre, RS, Brazil
| | - Eliane Dallegrave
- Graduate Program in Health Sciences, Federal University of Health Sciences of Porto Alegre, Porto Alegre, RS, Brazil
| | - Josias Merib
- Graduate Program in Biosciences, Federal University of Health Sciences of Porto Alegre, Porto Alegre, RS, Brazil
| | - Sarah Eller
- Graduate Program in Health Sciences, Federal University of Health Sciences of Porto Alegre, Porto Alegre, RS, Brazil
| | - Tiago Franco de Oliveira
- Graduate Program in Health Sciences, Federal University of Health Sciences of Porto Alegre, Porto Alegre, RS, Brazil
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Baqer Almayali EJ, Al-Kraety IAA, Maki Naji A, Abd almunaam LH. Bacteriological study and its antibiotics susceptibility pattern of Otitis Media in Iraqi patients. BIONATURA 2023; 8:1-7. [DOI: 10.21931/rb/2023.08.01.67] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/02/2023] Open
Abstract
Otitis media is an acute upper respiratory tract infection-related inflammation of the middle ear and tympanic membrane, frequently affecting children. Typically, a subsequent bacterial infection complicates a viral infection, which ultimately causes the condition. The study aims to study the function of bacterial ear infections and its causes, as well as their resistance to medications, which was the focus of this investigation. The first axis of the research was the identification of bacterial isolates using recognized diagnostic tools, and the second axis was determining the antibiotic's resistance and sensitivity. Patients with otitis media were gathered from Al-Hakim General Hospital and Al-Sadr city hospital in Al-Najaf city between November 2020 and April 2021 for 100 clinical samples. More than 80 samples were found to be infected with bacteria. Bacterial strains found in this investigation are ( 30 ) isolates of Pseudomonas aeruginosa, (20) isolates of Klebsiella spp, (20) isolates of Proteus spp, ( 15 ) isolates of Staphylococcus aureus, (8) isolates Escherichia coli and (7) isolates Enterococcus fecalies. As part of this research, the disk diffusion method was used to assess how sensitive the test was. The results showed that Pseudomonas aeruginosa was resistant to most antibiotics, particularly the penicillin family, cephalosporin, and trimethoprim, with the existence of isolates resistant to meropenem. The investigation results varied for the quinolone, aminoglycoside, and macrolide families. Klebsiella spp. were tested for antibiotic sensitivity and found to be resistant to most antibiotics, particularly those in the penicillin family, cephalosporins, and trimethoprim. Some quinolones, aminoglycosides, and macrolides are also resistant. Proteus spp were resistant to most antibiotics, particularly the penicillin family (except for augmentin, which had some sensitive isolates) and cephalosporin (except for cefdinir and cefepime) had some susceptible isolates) and trimethoprim, in addition to the presence of isolates resistant to meropenem. There is a discrepancy in the examination results for the quinolone family. The aminoglycoside family is also highly resistant. S. aureus isolates were resistant to penicillin (except for augmentin, which some isolates were responsive to), trimethoprim, and quinolones, with the presence of isolates resistant to vancomycin. The macrolide class ( azithromycin) also has a significant resistance level. Escherichia coli is susceptible to meropenem, imipenem, and certain cephalosporin generations. Augmentin, cefepime, cephalothin, meropenem, imipenem, and azithromycin were ineffective against Enterococcus fecal. The conclusion is that Pseudomonas spp has a role in ear infections and the germs Klebsiella spp., Proteus spp., Staphylococcus aureus, Escherichia coli, and Enterococcus fecalies. Penicillin and cephalosporin resistance was seen in the majority of the identified isolates. The existence of isolates of Proteus and Pseudomonas species resistant to meropenem. Vancomycin-resistant strains of Staphylococcus aureus isolates are present.
Keywords: Otitis media, Resistance antibiotic, S.aureus, P.aerginosa
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Affiliation(s)
- Enas Jalil Baqer Almayali
- Department of Medical Laboratory Technique, Faculty of Medical and Health Technique, University of Alkafeel. Najaf, Iraq
| | - Israa Abdul Ameer Al-Kraety
- Department of Medical Laboratory Technique, Faculty of Medical and Health Technique, University of Alkafeel. Najaf, Iraq
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7
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Jiang F, Cai C, Gao L, Su X, Han S. Peptidoglycan-Directed Chemical Ligation for Selective Inhibition on Gram-Positive Bacteria. ACS OMEGA 2023; 8:2485-2490. [PMID: 36687063 PMCID: PMC9850734 DOI: 10.1021/acsomega.2c06964] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/29/2022] [Accepted: 12/16/2022] [Indexed: 06/17/2023]
Abstract
Microbicides with distinct antibacterial mechanisms show potential to combat multi-drug resistance bacteria. We herein report peptidoglycan-directed chemical ligation (PGCL) between alkyne-bearing vancomycin and an azide-tagged cationic polymer. The former binds peptidoglycan and inhibits peptidoglycan crosslinking, while the latter interferes the integrity of the bacterial membrane. PGCL results in enhanced bactericidal activity against Gram-positive Staphylococcus aureus (S. aureus) over Gram-negative Escherichia coli (E. coli). These data indicate the potential of PGCL to selectively and synergistically inhibit Gram-positive pathogens via dual modality antibacterial mechanisms of peptidoglycan-inhibiting antibiotics and bacterial membrane-disrupting polycations.
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Affiliation(s)
- Feng Jiang
- Department
of Chemical Biology, College of Chemistry and Chemical Engineering,
State Key Laboratory for Physical Chemistry of Solid Surfaces, State
Key Laboratory of Cellular Stress Biology, the Key Laboratory for
Chemical Biology of Fujian Province, and the MOE Key Laboratory of
Spectrochemical Analysis & Instrumentation, Xiamen University, Xiamen 361005, China
| | - Chengteng Cai
- Department
of Chemical Biology, College of Chemistry and Chemical Engineering,
State Key Laboratory for Physical Chemistry of Solid Surfaces, State
Key Laboratory of Cellular Stress Biology, the Key Laboratory for
Chemical Biology of Fujian Province, and the MOE Key Laboratory of
Spectrochemical Analysis & Instrumentation, Xiamen University, Xiamen 361005, China
| | - Lei Gao
- Department
of Chemical Biology, College of Chemistry and Chemical Engineering,
State Key Laboratory for Physical Chemistry of Solid Surfaces, State
Key Laboratory of Cellular Stress Biology, the Key Laboratory for
Chemical Biology of Fujian Province, and the MOE Key Laboratory of
Spectrochemical Analysis & Instrumentation, Xiamen University, Xiamen 361005, China
| | - Xinhui Su
- PET
center, Department of Nuclear Medicine, The First Affiliated Hospital,
College of Medicine, Zhejiang University, Hangzhou 310027, China
| | - Shoufa Han
- Department
of Chemical Biology, College of Chemistry and Chemical Engineering,
State Key Laboratory for Physical Chemistry of Solid Surfaces, State
Key Laboratory of Cellular Stress Biology, the Key Laboratory for
Chemical Biology of Fujian Province, and the MOE Key Laboratory of
Spectrochemical Analysis & Instrumentation, Xiamen University, Xiamen 361005, China
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8
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Theillet FX, Luchinat E. In-cell NMR: Why and how? PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2022; 132-133:1-112. [PMID: 36496255 DOI: 10.1016/j.pnmrs.2022.04.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Revised: 04/19/2022] [Accepted: 04/27/2022] [Indexed: 06/17/2023]
Abstract
NMR spectroscopy has been applied to cells and tissues analysis since its beginnings, as early as 1950. We have attempted to gather here in a didactic fashion the broad diversity of data and ideas that emerged from NMR investigations on living cells. Covering a large proportion of the periodic table, NMR spectroscopy permits scrutiny of a great variety of atomic nuclei in all living organisms non-invasively. It has thus provided quantitative information on cellular atoms and their chemical environment, dynamics, or interactions. We will show that NMR studies have generated valuable knowledge on a vast array of cellular molecules and events, from water, salts, metabolites, cell walls, proteins, nucleic acids, drugs and drug targets, to pH, redox equilibria and chemical reactions. The characterization of such a multitude of objects at the atomic scale has thus shaped our mental representation of cellular life at multiple levels, together with major techniques like mass-spectrometry or microscopies. NMR studies on cells has accompanied the developments of MRI and metabolomics, and various subfields have flourished, coined with appealing names: fluxomics, foodomics, MRI and MRS (i.e. imaging and localized spectroscopy of living tissues, respectively), whole-cell NMR, on-cell ligand-based NMR, systems NMR, cellular structural biology, in-cell NMR… All these have not grown separately, but rather by reinforcing each other like a braided trunk. Hence, we try here to provide an analytical account of a large ensemble of intricately linked approaches, whose integration has been and will be key to their success. We present extensive overviews, firstly on the various types of information provided by NMR in a cellular environment (the "why", oriented towards a broad readership), and secondly on the employed NMR techniques and setups (the "how", where we discuss the past, current and future methods). Each subsection is constructed as a historical anthology, showing how the intrinsic properties of NMR spectroscopy and its developments structured the accessible knowledge on cellular phenomena. Using this systematic approach, we sought i) to make this review accessible to the broadest audience and ii) to highlight some early techniques that may find renewed interest. Finally, we present a brief discussion on what may be potential and desirable developments in the context of integrative studies in biology.
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Affiliation(s)
- Francois-Xavier Theillet
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198 Gif-sur-Yvette, France.
| | - Enrico Luchinat
- Dipartimento di Scienze e Tecnologie Agro-Alimentari, Alma Mater Studiorum - Università di Bologna, Piazza Goidanich 60, 47521 Cesena, Italy; CERM - Magnetic Resonance Center, and Neurofarba Department, Università degli Studi di Firenze, 50019 Sesto Fiorentino, Italy
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9
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Ni C, Zhong Y, Wu W, Song Y, Makvandi P, Yu C, Song H. Co-Delivery of Nano-Silver and Vancomycin via Silica Nanopollens for Enhanced Antibacterial Functions. Antibiotics (Basel) 2022; 11:antibiotics11050685. [PMID: 35625329 PMCID: PMC9137463 DOI: 10.3390/antibiotics11050685] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2022] [Revised: 05/14/2022] [Accepted: 05/17/2022] [Indexed: 12/13/2022] Open
Abstract
Infectious diseases caused by bacteria have led to a great threat to public health. With the significant advances in nanotechnology in recent decades, nanomaterials have emerged as a powerful tool to boost antibacterial performance due to either intrinsic bactericidal properties or by enhancing the delivery efficiency of antibiotics for effective pathogen killing. Vancomycin, as one of the most widely employed antimicrobial peptides, has a potent bactericidal activity, but at the same time shows a limited bioavailability. Silver nanoparticles have also been extensively explored and were found to have a well-recognized antibacterial activity and limited resistance potential; however, how to prevent nanosized Ag particles from aggregation in biological conditions is challenging. In this study, we aimed to combine the advantages of both vancomycin and nano-Ag for enhanced bacterial killing, where both antibacterial agents were successfully loaded onto a silica nanoparticle with a pollen-like morphology. The morphology of nano-Ag-decorated silica nanopollens was characterized using transmission electron microscopy and elemental mapping through energy dispersive spectroscopy. Silver nanoparticles with a size of 10–25 nm were observed as well-distributed on the surface of silica nanoparticles of around 200 nm. The unique design of a spiky morphology of silica nano-carriers promoted the adhesion of nanoparticles towards bacterial surfaces to promote localized drug release for bacterial killing, where the bacterial damage was visualized through scanning electron microscopy. Enhanced bactericidal activity was demonstrated through this co-delivery of vancomycin and nano-Ag, decreasing the minimum inhibition concentration (MIC) towards E. coli and S. epidermidis down to 15 and 10 µg/mL. This study provides an efficient antimicrobial nano-strategy to address potential bacterial infections.
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Affiliation(s)
- Chengang Ni
- Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, Brisbane 4072, Australia; (C.N.); (Y.Z.); (W.W.); (Y.S.); (C.Y.)
| | - Yuening Zhong
- Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, Brisbane 4072, Australia; (C.N.); (Y.Z.); (W.W.); (Y.S.); (C.Y.)
| | - Weixi Wu
- Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, Brisbane 4072, Australia; (C.N.); (Y.Z.); (W.W.); (Y.S.); (C.Y.)
| | - Yaping Song
- Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, Brisbane 4072, Australia; (C.N.); (Y.Z.); (W.W.); (Y.S.); (C.Y.)
| | - Pooyan Makvandi
- Center for Materials Interfaces, Istituto Italiano di Tecnologia, Pontedera, 56025 Pisa, Italy;
| | - Chengzhong Yu
- Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, Brisbane 4072, Australia; (C.N.); (Y.Z.); (W.W.); (Y.S.); (C.Y.)
| | - Hao Song
- Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, Brisbane 4072, Australia; (C.N.); (Y.Z.); (W.W.); (Y.S.); (C.Y.)
- Correspondence:
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10
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Olademehin OP, Shuford KL, Kim SJ. Molecular dynamics simulations of the secondary-binding site in disaccharide-modified glycopeptide antibiotics. Sci Rep 2022; 12:7087. [PMID: 35490171 PMCID: PMC9056522 DOI: 10.1038/s41598-022-10735-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Accepted: 04/12/2022] [Indexed: 11/16/2022] Open
Abstract
Oritavancin is a semisynthetic glycopeptide antibiotic used to treat severe infections by multidrug-resistant Gram-positive pathogens. Oritavancin is known to be a thousand times more potent than vancomycin against Gram-positive bacteria due to the additional interactions with bacterial peptidoglycan (PG) facilitated by a secondary-binding site. The presence of this secondary-binding site is evident in desleucyl-oritavancin, an Edman degradation product of oritavancin, still retaining its potency against Gram-positive bacteria, whereas desleucyl-vancomycin is devoid of any antimicrobial activities. Herein, using explicit solvent molecular dynamics (MD) simulations, steered MD simulations, and umbrella sampling, we show evidence of a secondary-binding site mediated by the disaccharide-modified hydrophobic sidechain of oritavancin interactions with the pentaglycyl-bridge segment of the PG. The interactions were characterized through comparison to the interaction of PG with chloroeremomycin, vancomycin, and the desleucyl analogs of the glycopeptides. Our results show that the enhanced binding of oritavancin to PG over the binding of the other complexes studied is due to an increase in the hydrophobic effect, electrostatic and van der Waals interactions, and not the average number of hydrogen bonds. Our ranking of the binding interactions of the biomolecular complexes directly correlates with the order based on their experimental minimum inhibitory concentrations. The results of our simulations provide insight into the modification of glycopeptides to increase their antimicrobial activities or the design of novel antibiotics against pathogenic Gram-positive bacteria.
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Affiliation(s)
| | - Kevin L Shuford
- Department of Chemistry and Biochemistry, Baylor University, Waco, TX, 76706, USA.
| | - Sung J Kim
- Department of Chemistry, Howard University, Washington, DC, 20059, USA.
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11
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Vancomycin-Associated Acute Kidney Injury: A Narrative Review from Pathophysiology to Clinical Application. Int J Mol Sci 2022; 23:ijms23042052. [PMID: 35216167 PMCID: PMC8877514 DOI: 10.3390/ijms23042052] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Revised: 02/10/2022] [Accepted: 02/11/2022] [Indexed: 12/12/2022] Open
Abstract
Vancomycin is the most frequently used antibiotic, accounting for up to 35% of hospitalized patients with infection, because of its optimal bactericidal effectiveness and relatively low price. Vancomycin-associated AKI (VA-AKI) is a clinically relevant but not yet clearly understood entity in critically ill patients. The current review comprehensively summarizes the pathophysiological mechanisms of, biomarkers for, preventive strategies for, and some crucial issues with VA-AKI. The pathological manifestations of VA-AKI include acute tubular necrosis, acute tubulointerstitial nephritis (ATIN), and intratubular crystal obstruction. The proposed pathological mechanisms of VA-AKI include oxidative stress and allergic reactions induced by vancomycin and vancomycin-associated tubular casts. Concomitant administration with other nephrotoxic antibiotics, such as piperacillin–tazobactam, high vancomycin doses, and intermittent infusion strategies compared to the continuous infusion are associated with a higher risk of VA-AKI. Several biomarkers could be applied to predict and diagnose VA-AKI. To date, no promising therapy is available. Oral steroids could be considered for patients with ATIN, whereas hemodialysis might be applied to remove vancomycin from the patient. In the future, disclosing more promising biomarkers that could precisely identify populations susceptible to VA-AKI and detect VA-AKI occurrence early on, and developing pharmacological agents that could prevent or treat VA-AKI, are the keys to improve the prognoses of patients with severe infection who probably need vancomycin therapy.
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12
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Ghassemi N, Poulhazan A, Deligey F, Mentink-Vigier F, Marcotte I, Wang T. Solid-State NMR Investigations of Extracellular Matrixes and Cell Walls of Algae, Bacteria, Fungi, and Plants. Chem Rev 2021; 122:10036-10086. [PMID: 34878762 DOI: 10.1021/acs.chemrev.1c00669] [Citation(s) in RCA: 55] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Extracellular matrixes (ECMs), such as the cell walls and biofilms, are important for supporting cell integrity and function and regulating intercellular communication. These biomaterials are also of significant interest to the production of biofuels and the development of antimicrobial treatment. Solid-state nuclear magnetic resonance (ssNMR) and magic-angle spinning-dynamic nuclear polarization (MAS-DNP) are uniquely powerful for understanding the conformational structure, dynamical characteristics, and supramolecular assemblies of carbohydrates and other biomolecules in ECMs. This review highlights the recent high-resolution investigations of intact ECMs and native cells in many organisms spanning across plants, bacteria, fungi, and algae. We spotlight the structural principles identified in ECMs, discuss the current technical limitation and underexplored biochemical topics, and point out the promising opportunities enabled by the recent advances of the rapidly evolving ssNMR technology.
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Affiliation(s)
- Nader Ghassemi
- Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, United States
| | - Alexandre Poulhazan
- Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, United States.,Department of Chemistry, Université du Québec à Montréal, Montreal H2X 2J6, Canada
| | - Fabien Deligey
- Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, United States
| | | | - Isabelle Marcotte
- Department of Chemistry, Université du Québec à Montréal, Montreal H2X 2J6, Canada
| | - Tuo Wang
- Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, United States
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13
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Unlocking the bacterial membrane as a therapeutic target for next-generation antimicrobial amphiphiles. Mol Aspects Med 2021; 81:100999. [PMID: 34325929 DOI: 10.1016/j.mam.2021.100999] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2021] [Revised: 06/21/2021] [Accepted: 07/16/2021] [Indexed: 11/21/2022]
Abstract
Gram-positive bacteria like Enterococcus faecium and Staphylococcus aureus, and Gram-negative bacteria like Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter Spp. are responsible for most of fatal bacterial infections. Bacteria present a handful of targets like ribosome, RNA polymerase, cell wall biosynthesis, and dihydrofolate reductase. Antibiotics targeting the protein synthesis like aminoglycosides and tetracyclines, inhibitors of RNA/DNA synthesis like fluoroquinolones, inhibitors of cell wall biosynthesis like glycopeptides and β-lactams, and membrane-targeting polymyxins and lipopeptides have shown very good success in combating the bacterial infections. Ability of the bacteria to develop drug resistance is a serious public health challenge as bacteria can develop antimicrobial resistance against newly introduced antibiotics that enhances the challenge for antibiotic drug discovery. Therefore, bacterial membranes present a suitable therapeutic target for development of antimicrobials as bacteria can find it difficult to develop resistance against membrane-targeting antimicrobials. In this review, we present the recent advances in engineering of membrane-targeting antimicrobial amphiphiles that can be effective alternatives to existing antibiotics in combating bacterial infections.
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14
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Virulence alterations in staphylococcus aureus upon treatment with the sub-inhibitory concentrations of antibiotics. J Adv Res 2021; 31:165-175. [PMID: 34194840 PMCID: PMC8240104 DOI: 10.1016/j.jare.2021.01.008] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Revised: 01/09/2021] [Accepted: 01/12/2021] [Indexed: 12/24/2022] Open
Abstract
Background The treatment of patients with Staphylococcus aureus infections mainly relies on antistaphylococcal regimens that are established with effective antibiotics. In antibiotic therapy or while living in nature, pathogens often face the sub-inhibitory concentrations (sub-MICs) of antibiotics due to drug pharmacokinetics, diffusion barriers, waste emission, resistant organism formation, and farming application. Different categories of antibiotics at sub-MICs have diverse effects on the physiological and chemical properties of microorganisms. These effects can result in virulence alterations. However, the mechanisms underlying the actions of antibiotics at sub-MICs on S. aureus virulence are obscure. Aim of review In this review, we focus on the effects of sub-MICs of antibiotics on S. aureus virulence from the aspects of cell morphological change, virulence factor expression, bacterial adherence and invasion, staphylococcal biofilm formation, and small-colony variant (SCV) production. The possible mechanisms of antibiotic-induced S. aureus virulence alterations are also addressed. Key scientific concepts of review Five main aspects of bacterial virulence can be changed in S. aureus exposure to the sub-MIC levels of antibiotics, resulting in deformed bacterial cells to stimulate abnormal host immune responses, abnormally expressed virulence factors to alter disease development, changed bacterial adhesion and invasion abilities to affect colonization and diffusion, altered biofilm formation to potentate material-related infections, and increased SCV formation to achieve persistent infection and recurrence. These advanced findings expand our knowledge to rethink the molecular signaling roles of antibiotics beyond their actions as antimicrobial agents.
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15
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Baral B, Mozafari MR. Strategic Moves of "Superbugs" Against Available Chemical Scaffolds: Signaling, Regulation, and Challenges. ACS Pharmacol Transl Sci 2020; 3:373-400. [PMID: 32566906 PMCID: PMC7296549 DOI: 10.1021/acsptsci.0c00005] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2020] [Indexed: 12/12/2022]
Abstract
Superbugs' resistivity against available natural products has become an alarming global threat, causing a rapid deterioration in public health and claiming tens of thousands of lives yearly. Although the rapid discovery of small molecules from plant and microbial origin with enhanced bioactivity has provided us with some hope, a rapid hike in the resistivity of superbugs has proven to be the biggest therapeutic hurdle of all times. Moreover, several distinct mechanisms endowed by these notorious superbugs make them immune to these antibiotics subsequently causing our antibiotic wardrobe to be obsolete. In this unfortunate situation, though the time frame for discovering novel "hit molecules" down the line remains largely unknown, our small hope and untiring efforts injected in hunting novel chemical scaffolds with unique molecular targets using high-throughput technologies may safeguard us against these life-threatening challenges to some extent. Amid this crisis, the current comprehensive review highlights the present status of knowledge, our search for bacteria Achilles' heel, distinct molecular signaling that an opportunistic pathogen bestows to trespass the toxicity of antibiotics, and facile strategies and appealing therapeutic targets of novel drugs. Herein, we also discuss multidimensional strategies to combat antimicrobial resistance.
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Affiliation(s)
- Bikash Baral
- Department
of Biochemistry, University of Turku, Tykistökatu 6, Turku, Finland
| | - M. R. Mozafari
- Australasian
Nanoscience and Nanotechnology Initiative, 8054 Monash University LPO, Clayton, Victoria 3168, Australia
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16
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Bougault C, Ayala I, Vollmer W, Simorre JP, Schanda P. Studying intact bacterial peptidoglycan by proton-detected NMR spectroscopy at 100 kHz MAS frequency. J Struct Biol 2018; 206:66-72. [PMID: 30031884 DOI: 10.1016/j.jsb.2018.07.009] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Revised: 06/19/2018] [Accepted: 07/12/2018] [Indexed: 12/19/2022]
Abstract
The bacterial cell wall is composed of the peptidoglycan (PG), a large polymer that maintains the integrity of the bacterial cell. Due to its multi-gigadalton size, heterogeneity, and dynamics, atomic-resolution studies are inherently complex. Solid-state NMR is an important technique to gain insight into its structure, dynamics and interactions. Here, we explore the possibilities to study the PG with ultra-fast (100 kHz) magic-angle spinning NMR. We demonstrate that highly resolved spectra can be obtained, and show strategies to obtain site-specific resonance assignments and distance information. We also explore the use of proton-proton correlation experiments, thus opening the way for NMR studies of intact cell walls without the need for isotope labeling.
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Affiliation(s)
- Catherine Bougault
- Univ. Grenoble Alpes, CEA, CNRS, Institute for Structural Biology (IBS), 71 avenue des martyrs, 38044 Grenoble, France
| | - Isabel Ayala
- Univ. Grenoble Alpes, CEA, CNRS, Institute for Structural Biology (IBS), 71 avenue des martyrs, 38044 Grenoble, France
| | - Waldemar Vollmer
- The Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Newcastle University, Richardson Road, Newcastle upon Tyne NE2 4AX, United Kingdom
| | - Jean-Pierre Simorre
- Univ. Grenoble Alpes, CEA, CNRS, Institute for Structural Biology (IBS), 71 avenue des martyrs, 38044 Grenoble, France.
| | - Paul Schanda
- Univ. Grenoble Alpes, CEA, CNRS, Institute for Structural Biology (IBS), 71 avenue des martyrs, 38044 Grenoble, France.
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17
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Wang F, Zhou H, Olademehin OP, Kim SJ, Tao P. Insights into Key Interactions between Vancomycin and Bacterial Cell Wall Structures. ACS OMEGA 2018; 3:37-45. [PMID: 29399648 PMCID: PMC5793038 DOI: 10.1021/acsomega.7b01483] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2017] [Accepted: 12/19/2017] [Indexed: 05/18/2023]
Abstract
Vancomycin is a glycopeptide antibiotic used for the treatment of serious infections by Gram-positive pathogens. Vancomycin inhibits cell wall biosynthesis by targeting the d-Ala-d-Ala terminus of peptidoglycan (PG). The highly cross-linked heptapeptide aglycon structure of vancomycin is the d-Ala-d-Ala binding site. The first residue of vancomycin is N-methyl-leucine, which is crucial for the dipeptide binding. The removal of N-methyl-leucine by Edman degradation results in desleucyl-vancomycin devoid of antimicrobial activities. To investigate the function of N-methyl-leucine for the dipeptide binding in vancomycin, molecular dynamics simulations of vancomycin and three N-terminus-modified vancomycin derivatives: desleucyl-vancomycin, vancomycinNtoC, and vancomycinSar, binding to a PG unit of the sequence l-Ala-d-iso-Gln-l-Lys-d-Ala-d-Ala with an intact pentaglycine bridge structure attached to the bridge link of l-Lys were carried out. Glycopeptide-PG binding interactions were characterized by root-mean-square-deviation contour analysis of atomic positions in vancomycin and its three analogues bound to a PG unit. The overall sampling space for four glycopeptide-PG complexes shows four distinct distributions with a continuous change between the conformational spaces. The hydrogen bond analyses show that multiple hydrogen bonds between the d-Ala-d-Ala and the vancomycin aglycon structure strengthened the dipeptide binding. The simulations revealed that the removal or chemical modification of N-methyl-leucine significantly weakens the dipeptide binding to the aglycon structure and provides interesting structural insights into glycopeptide-PG binding interactions.
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Affiliation(s)
- Feng Wang
- Department
of Chemistry, Center for Drug Discovery, Design, and Delivery (CD4),
Center for Scientific Computation, Southern
Methodist University, Dallas, Texas 75275, United States
| | - Hongyu Zhou
- Department
of Chemistry, Center for Drug Discovery, Design, and Delivery (CD4),
Center for Scientific Computation, Southern
Methodist University, Dallas, Texas 75275, United States
| | - Olatunde P. Olademehin
- Department
of Chemistry and Biochemistry, Baylor University, Waco, Texas 76706, United States
| | - Sung Joon Kim
- Department
of Chemistry and Biochemistry, Baylor University, Waco, Texas 76706, United States
| | - Peng Tao
- Department
of Chemistry, Center for Drug Discovery, Design, and Delivery (CD4),
Center for Scientific Computation, Southern
Methodist University, Dallas, Texas 75275, United States
- E-mail: . Phone: 1-214-768-8802. Fax: 1-214-768-4089 (P.T.)
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18
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Quinn CM, Wang M, Polenova T. NMR of Macromolecular Assemblies and Machines at 1 GHz and Beyond: New Transformative Opportunities for Molecular Structural Biology. Methods Mol Biol 2018; 1688:1-35. [PMID: 29151202 PMCID: PMC6217836 DOI: 10.1007/978-1-4939-7386-6_1] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
Abstract
As a result of profound gains in sensitivity and resolution afforded by ultrahigh magnetic fields, transformative applications in the fields of structural biology and materials science are being realized. The development of dual low temperature superconducting (LTS)/high-temperature superconducting (HTS) magnets has enabled the achievement of magnetic fields above 1 GHz (23.5 T), which will open doors to an unprecedented new range of applications. In this contribution, we discuss the promise of ultrahigh field magnetic resonance. We highlight several methodological developments pertinent at high-magnetic fields including measurement of 1H-1H distances and 1H chemical shift anisotropy in the solid state as well as studies of quadrupolar nuclei such as 17O. Higher magnetic fields have advanced heteronuclear detection in solution NMR, valuable for applications including metabolomics and disordered proteins, as well as expanded use of proton detection in the solid state in conjunction with ultrafast magic angle spinning. We also present several recent applications to structural studies of the AP205 bacteriophage, the M2 channel from Influenza A, and biomaterials such as human bone. Gains in sensitivity and resolution from increased field strengths will enable advanced applications of NMR spectroscopy including in vivo studies of whole cells and intact virions.
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Affiliation(s)
- Caitlin M Quinn
- Department of Chemistry and Biochemistry, University of Delaware, 036 Brown Laboratories, Newark, DE, 19716, USA
- Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine, 1051 Biomedical Science Tower 3, 3501 Fifth Ave, Pittsburgh, PA, 15261, USA
| | - Mingzhang Wang
- Department of Chemistry and Biochemistry, University of Delaware, 036 Brown Laboratories, Newark, DE, 19716, USA
- Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine, 1051 Biomedical Science Tower 3, 3501 Fifth Ave, Pittsburgh, PA, 15261, USA
| | - Tatyana Polenova
- Department of Chemistry and Biochemistry, University of Delaware, 036 Brown Laboratories, Newark, DE, 19716, USA.
- Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine, 1051 Biomedical Science Tower 3, 3501 Fifth Ave, Pittsburgh, PA, 15261, USA.
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19
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Inhibition of Staphylococcus aureus Cell Wall Biosynthesis by Desleucyl-Oritavancin: a Quantitative Peptidoglycan Composition Analysis by Mass Spectrometry. J Bacteriol 2017; 199:JB.00278-17. [PMID: 28507244 DOI: 10.1128/jb.00278-17] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2017] [Accepted: 05/07/2017] [Indexed: 11/20/2022] Open
Abstract
Oritavancin is a lipoglycopeptide antibiotic that exhibits potent activities against vancomycin-resistant Gram-positive pathogens. Oritavancin differs from vancomycin by a hydrophobic side chain attached to the drug disaccharide, which forms a secondary binding site to enable oritavancin binding to the cross-linked peptidoglycan in the cell wall. The mode of action of secondary binding site was investigated by measuring the changes in the peptidoglycan composition of Staphylococcus aureus grown in the presence of desleucyl-oritavancin at subinhibitory concentration using liquid chromatography-mass spectrometry (LC-MS). Desleucyl-oritavancin is an Edman degradation product of oritavancin that exhibits potent antibacterial activities despite the damaged d-Ala-d-Ala binding site due to its functional secondary binding site. Accurate quantitative peptidoglycan composition analysis based on 83 muropeptide ions determined that cell walls of S. aureus grown in the presence of desleucyl-oritavancin showed a reduction of peptidoglycan cross-linking, increased muropeptides with a tetrapeptide-stem structure, decreased O-acetylation of MurNAc, and increased N-deacetylation of GlcNAc. The changes in peptidoglycan composition suggest that desleucyl-oritavancin targets the peptidoglycan template to induce cell wall disorder and interferes with cell wall maturation.IMPORTANCE Oritavancin is a lipoglycopeptide antibiotic with a secondary binding site that targets the cross-linked peptidoglycan bridge structure in the cell wall. Even after the loss of its primary d-Ala-d-Ala binding site through Edman degradation, desleucyl-oritavancin exhibits potent antimicrobial activities through its still-functioning secondary binding site. In this study, we characterized the mode of action for desleucyl-oritavancin's secondary binding site using LC-MS. Peptidoglycan composition analysis of desleucyl-oritavancin-treated S. aureus was performed by determining the relative abundances of 83 muropeptide ions matched from a precalculated library through integrating extracted ion chromatograms. Our work highlights the use of quantitative peptidoglycan composition analysis by LC-MS to provide insights into the mode of action of glycopeptide antibiotics.
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20
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Chang J, Coffman L, Kim SJ. Inhibition of d-Ala incorporation into wall teichoic acid in Staphylococcus aureus by desleucyl-oritavancin. Chem Commun (Camb) 2017; 53:5649-5652. [PMID: 28480909 PMCID: PMC5512289 DOI: 10.1039/c7cc02635h] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/30/2023]
Abstract
The mode of action for desleucyl-oritavancin was investigated by adding an antibiotic to Staphylococcus aureus during its growth in a defined medium containing l,d-[1-15N]Ala and l-[1-13C]Lys, or d-[1-15N]Ala. 13C{15N} and 15N{13C} rotational-echo double resonance NMR determined that desleucyl-oritavancin inhibited the incorporation of d-[1-15N]Ala into wall teichoic acid.
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Affiliation(s)
- J Chang
- Department of Chemistry, Baylor University, One Bear Place #97348, Waco, Texas 76798, USA.
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21
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Singh M, Chang J, Coffman L, Kim SJ. Hidden Mode of Action of Glycopeptide Antibiotics: Inhibition of Wall Teichoic Acid Biosynthesis. J Phys Chem B 2017; 121:3925-3932. [PMID: 28368603 DOI: 10.1021/acs.jpcb.7b00324] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Glycopeptide antibiotics inhibit the peptidoglycan biosynthesis in Gram-positive bacteria by targeting lipid II. This prevents the recycling of bactoprenol phosphate, the lipid transporter that is shared by peptidoglycan and wall teichoic acid biosyntheses. In this study, we investigate the effects of glycopeptide antibiotics on peptidoglycan and wall teichoic acid biosynthesis. The incorporation of d-[1-13C]alanine, d-[15N]alanine, and l-[1-13C]lysine into peptidoglycan and wall teichoic acid in intact whole cells of Staphylococcus aureus was measured using 13C{15N} and 15N{13C} rotational-echo double resonance NMR. S. aureus treated with oritavancin and vancomycin at subminimal inhibitory concentrations exhibit a large reduction in d-Ala incorporation into wall teichoic acid, but without changes to the peptidoglycan cross-links or the stem-links. Thus, sequestration of bactoprenol phosphate by glycopeptide antibiotics resulted in inhibition of d-Ala incorporation into the wall teichoic acid prior to the inhibition of peptidoglycan biosynthesis. Our finding shows that S. aureus responds to glycopeptide-induced cell wall stress by routing all available d-Ala to the peptidoglycan biosynthesis, at the cost of reducing the wall teichoic acid biosynthesis.
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Affiliation(s)
- Manmilan Singh
- Department of Chemistry, Washington University , St. Louis, Missouri 63130, United States
| | - James Chang
- Department of Chemistry and Biochemistry, Baylor University , Waco, Texas 76798, United States
| | - Lauryn Coffman
- Department of Chemistry and Biochemistry, Baylor University , Waco, Texas 76798, United States
| | - Sung Joon Kim
- Department of Chemistry and Biochemistry, Baylor University , Waco, Texas 76798, United States
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22
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Kim SJ, Singh M, Sharif S, Schaefer J. Desleucyl-Oritavancin with a Damaged d-Ala-d-Ala Binding Site Inhibits the Transpeptidation Step of Cell-Wall Biosynthesis in Whole Cells of Staphylococcus aureus. Biochemistry 2017; 56:1529-1535. [PMID: 28221772 PMCID: PMC5508972 DOI: 10.1021/acs.biochem.6b01125] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We have used solid-state nuclear magnetic resonance to characterize the exact nature of the dual mode of action of oritavancin in preventing cell-wall assembly in Staphylococcus aureus. Measurements performed on whole cells labeled selectively in vivo have established that des-N-methylleucyl-N-4-(4-fluorophenyl)benzyl-chloroeremomycin, an Edman degradation product of [19F]oritavancin, which has a damaged d-Ala-d-Ala binding aglycon, is a potent inhibitor of the transpeptidase activity of cell-wall biosynthesis. The desleucyl drug binds to partially cross-linked peptidoglycan by a cleft formed between the drug aglycon and its biphenyl hydrophobic side chain. This type of binding site is present in other oritavancin-like glycopeptides, which suggests that for these drugs a similar transpeptidase inhibition occurs.
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Affiliation(s)
- Sung Joon Kim
- Department of Chemistry and Biochemistry, Baylor University, 101 Bagby Ave., Waco, TX 76798
| | - Manmilan Singh
- Department of Chemistry, Washington University, One Brookings Drive, St. Louis, MO 63130
| | - Shasad Sharif
- Department of Chemistry, Washington University, One Brookings Drive, St. Louis, MO 63130
| | - Jacob Schaefer
- Department of Chemistry, Washington University, One Brookings Drive, St. Louis, MO 63130
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23
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Chang JD, Foster EE, Yang H, Kim SJ. Quantification of the d-Ala-d-Lac-Terminated Peptidoglycan Structure in Vancomycin-Resistant Enterococcus faecalis Using a Combined Solid-State Nuclear Magnetic Resonance and Mass Spectrometry Analysis. Biochemistry 2017; 56:612-622. [PMID: 28040891 PMCID: PMC6906607 DOI: 10.1021/acs.biochem.6b00774] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Induction of vancomycin resistance in vancomycin-resistant enterococci (VRE) involves replacement of the d-Ala-d-Ala terminus of peptidoglycan (PG) stems with d-Ala-d-Lac, dramatically reducing the binding affinity of vancomycin for lipid II. Effects from vancomycin resistance induction in Enterococcus faecalis (ATCC 51299) were characterized using a combined solid-state nuclear magnetic resonance (NMR) and liquid chromatography-mass spectrometry (LC-MS) analysis. Solid-state NMR directly measured the total amounts of d-Lac and l,d-Ala metabolized from [2-13C]pyruvate, accumulated Park's nucleotide, and changes to the PG bridge-linking density during the early exponential growth phase (OD660 = 0.4) in intact whole cells of VRE. A high level of accumulation of depsipeptide-substituted Park's nucleotide consistent with the inhibition of the transglycosylation step of PG biosynthesis during the initial phase of vancomycin resistance was observed, while no changes to the PG bridge-linking density following the induction of vancomycin resistance were detected. This indicated that the attachment of the PG bridge to lipid II by the peptidyl transferases was not inhibited by the d-Ala-d-Lac-substituted PG stem structure in VRE. Compositions of mutanolysin-digested isolated cell walls of VRE grown with and without vancomycin resistance induction were determined by LC-MS. Muropeptides with PG stems terminating in d-Ala-d-Lac were found only in VRE grown in the presence of vancomycin. Percentages of muropeptides with a pentapeptide stem terminating in d-Ala-d-Lac for VRE grown in the presence of vancomycin were 26% for the midexponential phase (OD660 = 0.6) and 57% for the stationary growth phase (OD660 = 1.0). These high percentages indicate that d-Ala-d-Lac-substituted lipid II was efficiently utilized for PG biosynthesis in VRE.
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Affiliation(s)
- James D. Chang
- Department of Chemistry and Biochemistry, Baylor University, Waco, Texas 76798, United States
| | - Erin E. Foster
- Department of Chemistry and Biochemistry, Baylor University, Waco, Texas 76798, United States
| | - Hao Yang
- Department of Chemistry, Washington University, St. Louis, Missouri 63130, United States
| | - Sung Joon Kim
- Department of Chemistry and Biochemistry, Baylor University, Waco, Texas 76798, United States
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24
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Solid-state NMR characterization of amphomycin effects on peptidoglycan and wall teichoic acid biosyntheses in Staphylococcus aureus. Sci Rep 2016; 6:31757. [PMID: 27538449 PMCID: PMC4990924 DOI: 10.1038/srep31757] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2016] [Accepted: 07/27/2016] [Indexed: 11/09/2022] Open
Abstract
Amphomycin and MX-2401 are cyclic lipopeptides exhibiting bactericidal activities against Gram-positive pathogens. Amphomycin and MX-2401 share structural similarities with daptomycin, but unlike daptomycin they do not target bacterial membrane. In this study, we investigate in vivo modes of action for amphomycin and MX-2401 in intact whole cells of Staphylococcus aureus by measuring the changes of peptidoglycan and wall teichoic acid compositions using solid-state NMR. S. aureus were grown in a defined media containing isotope labels [1-13C]glycine and L-[ε-15N]lysin, L-[1-13C]lysine and D-[15N]alanine, or D-[1-13C]alanine and [15N]glycine, to selectively 13C-15N pair label peptidoglycan bridge-link, stem-link, and cross-link, respectively. 13C{15N} and 15N{13C} rotational-echo double resonance NMR measurements determined that cyclic lipopeptide-treated S. aureus exhibited thinning of the cell wall, accumulation of Park’s nucleotide, inhibition of glycine utilization for purine biosynthesis, reduction of ester-linked D-Ala in teichoic acids, and reduction of peptidoglycan cross-linking. Whole cell NMR analysis also revealed that S. aureus, in presence of amphomycin and MX-2401, maintained the incorporation of D-Ala during peptidoglycan biosynthesis while the incorporation of D-Ala into teichoic acids was inhibited. These effects are consistent with amphomycin’s dual inhibition of both peptidoglycan and wall teichoic acid biosyntheses in S. aureus.
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25
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Chang J, Zhou H, Preobrazhenskaya M, Tao P, Kim SJ. The Carboxyl Terminus of Eremomycin Facilitates Binding to the Non-d-Ala-d-Ala Segment of the Peptidoglycan Pentapeptide Stem. Biochemistry 2016; 55:3383-91. [PMID: 27243469 PMCID: PMC6020039 DOI: 10.1021/acs.biochem.6b00188] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Glycopeptide antibiotics inhibit cell wall biosynthesis in Gram-positive bacteria by targeting the peptidoglycan (PG) pentapeptide stem structure (l-Ala-d-iso-Gln-l-Lys-d-Ala-d-Ala). Structures of the glycopeptide complexed with a PG stem mimic have shown that the d-Ala-d-Ala segment is the primary drug binding site; however, biochemical evidence suggests that the glycopeptide-PG interaction involves more than d-Ala-d-Ala binding. Interactions of the glycopeptide with the non-d-Ala-d-Ala segment of the PG stem were investigated using solid-state nuclear magnetic resonance (NMR). LCTA-1421, a double (15)N-enriched eremomycin derivative with a C-terminal [(15)N]amide and [(15)N]Asn amide, was complexed with whole cells of Staphylococcus aureus grown in a defined medium containing l-[3-(13)C]Ala and d-[1-(13)C]Ala in the presence of alanine racemase inhibitor alaphosphin. (13)C{(15)N} and (15)N{(13)C} rotational-echo double-resonance (REDOR) NMR measurements determined the (13)C-(15)N internuclear distances between the [(15)N]Asn amide of LCTA-1421 and the (13)C atoms of the bound d-[1-(13)C]Ala-d-[1-(13)C]Ala to be 5.1 and 4.8 Å, respectively. These measurements also determined the distance from the C-terminal [(15)N]amide of LCTA-1421 to the l-[3-(13)C]Ala of PG to be 3.5 Å. The measured REDOR distance constraints position the C-terminus of the glycopeptide in the proximity of the l-Ala of the PG, suggesting that the C-terminus of the glycopeptide interacts near the l-Ala segment of the PG stem. In vivo REDOR measurements provided structural insight into how C-terminally modified glycopeptide antibiotics operate.
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Affiliation(s)
- James Chang
- Department of Chemistry and Biochemistry, Baylor University, Waco, TX 76706
| | - Hongyu Zhou
- Department of Chemistry, Center for Drug Discovery, Design, and Delivery (CD4), Center for Scientific Computation, Southern Methodist University, Dallas, TX 7 5275, USA
| | | | - Peng Tao
- Department of Chemistry, Center for Drug Discovery, Design, and Delivery (CD4), Center for Scientific Computation, Southern Methodist University, Dallas, TX 7 5275, USA
| | - Sung Joon Kim
- Department of Chemistry and Biochemistry, Baylor University, Waco, TX 76706
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26
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Nygaard R, Romaniuk JAH, Rice DM, Cegelski L. Spectral snapshots of bacterial cell-wall composition and the influence of antibiotics by whole-cell NMR. Biophys J 2016; 108:1380-1389. [PMID: 25809251 DOI: 10.1016/j.bpj.2015.01.037] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2014] [Accepted: 01/13/2015] [Indexed: 01/28/2023] Open
Abstract
Gram-positive bacteria surround themselves with a thick cell wall that is essential to cell survival and is a major target of antibiotics. Quantifying alterations in cell-wall composition are crucial to evaluating drug modes of action, particularly important for human pathogens that are now resistant to multiple antibiotics such as Staphylococcus aureus. Macromolecular and whole-cell NMR spectroscopy allowed us to observe the full panel of carbon and nitrogen pools in S. aureus cell walls and intact whole cells. We discovered that one-dimensional (13)C and (15)N NMR spectra, together with spectroscopic selections based on dipolar couplings as well as two-dimensional spin-diffusion measurements, revealed the dramatic compositional differences between intact cells and cell walls and allowed the identification of cell-wall signatures in whole-cell samples. Furthermore, the whole-cell NMR approach exhibited the sensitivity to detect distinct compositional changes due to treatment with the antibiotics fosfomycin (a cell-wall biosynthesis inhibitor) and chloramphenicol (a protein synthesis inhibitor). Whole cells treated with fosfomycin exhibited decreased peptidoglycan contributions while those treated with chloramphenicol contained a higher percentage of peptidoglycan as cytoplasmic protein content was reduced. Thus, general antibiotic modes of action can be identified by profiling the total carbon pools in intact whole cells.
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Affiliation(s)
- Rie Nygaard
- Department of Chemistry, Stanford University, Stanford, California
| | | | - David M Rice
- Department of Chemistry, Stanford University, Stanford, California
| | - Lynette Cegelski
- Department of Chemistry, Stanford University, Stanford, California.
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27
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Oritavancin: A New Lipoglycopeptide Antibiotic in the Treatment of Gram-Positive Infections. Infect Dis Ther 2016; 5:1-15. [PMID: 26831328 PMCID: PMC4811835 DOI: 10.1007/s40121-016-0103-4] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2015] [Indexed: 10/25/2022] Open
Abstract
Resistance among Gram-positive organisms has been steadily increasing over the last several years; however, the development of new antibiotics to treat infections caused from these organisms has fallen short of the emergent need. Specifically, resistance among Staphylococcus aureus and Enterococcus spp. to essential antibiotics is considered a major problem. Oritavancin is a semisynthetic lipoglycopeptide antibiotic that was recently approved for the treatment of acute bacterial skin and skin structure infections (ABSSSI). While structurally related to vancomycin, oritavancin also possesses unique mechanisms of action that greatly enhance its antimicrobial potency against multi-drug resistant pathogens including both VanA- and VanB-mediated vancomycin-resistant enterococci. Owing to the addition of the highly hydrophobic tail group, oritavancin possesses a prolonged half-life ranging from 200-300 h. Although oritavancin is only currently Food and Drug Administration approved for ABSSSI, this agent may eventually play a role in additional indications where new innovative therapy is needed including bacteremia and deep-seeded, Gram-positive infections such as infective endocarditis or osteomyelitis. This review will focus on oritavancin's spectrum of activity, mechanisms of action and resistance, pharmacokinetic and pharmacodynamic properties, and the completed and ongoing clinical studies evaluating its use.
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28
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Wadzinski TJ, Gea KD, Miller SJ. A stepwise dechlorination/cross-coupling strategy to diversify the vancomycin 'in-chloride'. Bioorg Med Chem Lett 2015; 26:1025-1028. [PMID: 26725950 DOI: 10.1016/j.bmcl.2015.12.027] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2015] [Revised: 12/09/2015] [Accepted: 12/10/2015] [Indexed: 01/27/2023]
Abstract
In an effort to rapidly access vancomycin analogues bearing diverse functionality at the 6c-Cl (the 'in-chloride') position, a two-step dechlorination/cross-coupling protocol was developed. Conditions for efficient cross-coupling of the relatively unreactive 6c-Cl group were found that ensure high conversion with minimal product decomposition. A set of 2c-dechloro-6c-functionalized vancomycin derivatives was prepared, and antibiotic activities of the compounds were evaluated against a panel of vancomycin-resistant and vancomycin-susceptible strains. Results from biological testing further underscore the steric sensitivity of vancomycin's binding pocket.
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Affiliation(s)
- Tyler J Wadzinski
- Department of Chemistry, Yale University, PO Box 208107, New Haven, CT 06520-8107, United States
| | - Katherine D Gea
- Department of Chemistry, Yale University, PO Box 208107, New Haven, CT 06520-8107, United States
| | - Scott J Miller
- Department of Chemistry, Yale University, PO Box 208107, New Haven, CT 06520-8107, United States.
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29
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Rice DM, Romaniuk JAH, Cegelski L. Frequency-selective REDOR and spin-diffusion relays in uniformly labeled whole cells. SOLID STATE NUCLEAR MAGNETIC RESONANCE 2015; 72:132-9. [PMID: 26493462 PMCID: PMC4674448 DOI: 10.1016/j.ssnmr.2015.10.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Revised: 10/07/2015] [Accepted: 10/08/2015] [Indexed: 06/05/2023]
Abstract
Solid-state NMR is a powerful and non-perturbative method to measure and define chemical composition and architecture in bacterial cell walls, even in the context of whole cells. Most NMR studies on whole cells have used selectively labeled samples. Here, we introduce an NMR sequence relay using frequency-selective REDOR (fsREDOR) and spin diffusion elements to probe a unique amine contribution in uniformly (13)C- and (15)N-labeled Staphylococcus aureus whole cells that we attribute to the d-alanine of teichoic acid. In addition to the primary peptidoglycan structural scaffold, cell walls can contain significant amounts of teichoic acid that contribute to cell-wall function. When incorporated into teichoic acid, d-alanine is present as an ester, connected via its carbonyl to a ribitol carbon, and thus has a free amine. Teichoic acid d-Ala is removed during cell-wall isolations and can only be detected in the context of whole cells. The sequence presented here begins with fsREDOR and a chemical shift evolution period for 2D data acquisition, followed by DARR spin diffusion and then an additional fsREDOR period. fsREDOR elements were used for (13)C observation to avoid complications from (13)C-(13)C couplings due to uniform labeling and for (15)N dephasing to achieve selectivity in the nitrogens serving as dephasers. The results show that the selected amine nitrogen of interest is near to teichoic acid ribitol carbons and also the methyl group carbon associated with alanine. In addition, its carbonyl is not significantly dephased by amide nitrogens, consistent with the expected microenvironment around teichoic acid.
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Affiliation(s)
- David M Rice
- Stanford University, Department of Chemistry, 380 Roth Way, Stanford, CA 94305, USA
| | - Joseph A H Romaniuk
- Stanford University, Department of Chemistry, 380 Roth Way, Stanford, CA 94305, USA
| | - Lynette Cegelski
- Stanford University, Department of Chemistry, 380 Roth Way, Stanford, CA 94305, USA.
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30
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Kim SJ, Chang J, Singh M. Peptidoglycan architecture of Gram-positive bacteria by solid-state NMR. BIOCHIMICA ET BIOPHYSICA ACTA 2015; 1848:350-62. [PMID: 24915020 PMCID: PMC4258515 DOI: 10.1016/j.bbamem.2014.05.031] [Citation(s) in RCA: 96] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2014] [Revised: 05/30/2014] [Accepted: 05/31/2014] [Indexed: 10/25/2022]
Abstract
Peptidoglycan is an essential component of cell wall in Gram-positive bacteria with unknown architecture. In this review, we summarize solid-state NMR approaches to address some of the unknowns in the Gram-positive bacteria peptidoglycan architecture: 1) peptidoglycan backbone conformation, 2) PG-lattice structure, 3) variations in the peptidoglycan architecture and composition, 4) the effects of peptidoglycan bridge-length on the peptidoglycan architecture in Fem mutants, 5) the orientation of glycan strands with respect to the membrane, and 6) the relationship between the peptidoglycan structure and the glycopeptide antibiotic mode of action. Solid-state NMR analyses of Staphylococcus aureus cell wall show that peptidoglycan chains are surprisingly ordered and densely packed. The peptidoglycan disaccharide backbone adopts 4-fold screw helical symmetry with the disaccharide unit periodicity of 40Å. Peptidoglycan lattice in the S. aureus cell wall is formed by cross-linked PG stems that have parallel orientations. The structural characterization of Fem-mutants of S. aureus with varying lengths of bridge structures suggests that the PG-bridge length is an important determining factor for the PG architecture.
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Affiliation(s)
- Sung Joon Kim
- Department of Chemistry and Biochemistry, Baylor University, Waco, TX 76706, USA.
| | - James Chang
- Department of Chemistry and Biochemistry, Baylor University, Waco, TX 76706, USA
| | - Manmilan Singh
- Department of Chemistry, Washington University, St. Louis, MO 63130, USA
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31
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The activity of glycopeptide antibiotics against resistant bacteria correlates with their ability to induce the resistance system. Antimicrob Agents Chemother 2014; 58:6306-10. [PMID: 25092694 DOI: 10.1128/aac.03668-14] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Glycopeptide antibiotics containing a hydrophobic substituent display the best activity against vancomycin-resistant enterococci, and they have been assumed to be poor inducers of the resistance system. Using a panel of 26 glycopeptide derivatives and the model resistance system in Streptomyces coelicolor, we confirmed this hypothesis at the level of transcription. Identification of the structural glycopeptide features associated with inducing the expression of resistance genes has important implications in the search for more effective antibiotic structures.
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32
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Kim SJ, Singh M, Sharif S, Schaefer J. Cross-link formation and peptidoglycan lattice assembly in the FemA mutant of Staphylococcus aureus. Biochemistry 2014; 53:1420-7. [PMID: 24517508 PMCID: PMC3985804 DOI: 10.1021/bi4016742] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2013] [Revised: 02/09/2014] [Indexed: 11/29/2022]
Abstract
Staphylococcus aureus FemA mutant grown in the presence of an alanine-racemase inhibitor was labeled with d-[1-(13)C]alanine, l-[3-(13)C]alanine, [2-(13)C]glycine, and l-[5-(19)F]lysine to characterize some details of the peptidoglycan tertiary structure. Rotational-echo double-resonance (REDOR) NMR of isolated cell walls was used to measure internuclear distances between (13)C-labeled alanines and (19)F-labeled lysine incorporated in the peptidoglycan. The alanyl (13)C labels were preselected for REDOR measurement by their proximity to the glycine label using (13)C-(13)C spin diffusion. The observed (13)C-(13)C and (13)C-(19)F distances are consistent with a tightly packed, hybrid architecture containing both parallel and perpendicular stems in a repeating structural motif within the peptidoglycan.
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Affiliation(s)
- Sung Joon Kim
- Department
of Chemistry and Biochemistry, Baylor University, Waco, Texas 76706, United States
| | - Manmilan Singh
- Department
of Chemistry, Washington University, St. Louis, Missouri 63130, United
States
| | - Shasad Sharif
- Department
of Chemistry, Washington University, St. Louis, Missouri 63130, United
States
| | - Jacob Schaefer
- Department
of Chemistry, Washington University, St. Louis, Missouri 63130, United
States
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33
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Huang SH, Wu WS, Huang LY, Huang WF, Fu WC, Chen PT, Fang JM, Cheng WC, Cheng TJR, Wong CH. New continuous fluorometric assay for bacterial transglycosylase using Förster resonance energy transfer. J Am Chem Soc 2013; 135:17078-89. [PMID: 24131464 DOI: 10.1021/ja407985m] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The emergence of antibiotic resistance has prompted scientists to search for new antibiotics. Transglycosylase (TGase) is an attractive target for new antibiotic discovery due to its location on the outer membrane of bacteria and its essential role in peptidoglycan synthesis. Though there have been a few molecules identified as TGase inhibitors in the past thirty years, none of them have been developed into antibiotics for humans. The slow pace of development is perhaps due to the lack of continuous, quantitative, and high-throughput assay available for the enzyme. Herein, we report a new continuous fluorescent assay based on Förster resonance energy transfer, using lipid II analogues with a dimethylamino-azobenzenesulfonyl quencher in the lipid chain and a coumarin fluorophore in the peptide chain. During the process of transglycosylation, the quencher-appended polyprenol is released and the fluorescence of coumarin can be detected. Using this system, the substrate specificity and affinity of lipid II analogues bearing various numbers and configurations of isoprene units were investigated. Moreover, the inhibition constants of moenomycin and two previously identified small molecules were also determined. In addition, a high-throughput screening using the new assay was conducted to identify potent TGase inhibitors from a 120,000 compound library. This new continuous fluorescent assay not only provides an efficient and convenient way to study TGase activities, but also enables the high-throughput screening of potential TGase inhibitors for antibiotic discovery.
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Affiliation(s)
- Shih-Hsien Huang
- Genomics Research Center, Academia Sinica , 128 Academia Road, Section 2, Nankang, Taipei, 115, Taiwan
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34
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Cegelski L. REDOR NMR for drug discovery. Bioorg Med Chem Lett 2013; 23:5767-75. [PMID: 24035486 PMCID: PMC4038398 DOI: 10.1016/j.bmcl.2013.08.064] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2013] [Revised: 08/12/2013] [Accepted: 08/14/2013] [Indexed: 11/19/2022]
Abstract
Rotational-echo double-resonance (REDOR) NMR is a powerful and versatile solid-state NMR measurement that has been recruited to elucidate drug modes of action and to drive the design of new therapeutics. REDOR has been implemented to examine composition, structure, and dynamics in diverse macromolecular and whole-cell systems, including taxol-bound microtubules, enzyme-cofactor-inhibitor ternary complexes, and antibiotic-whole-cell complexes. The REDOR approach involves the integrated design of specific isotopic labeling strategies and the selection of appropriate REDOR experiments. By way of example, this digest illustrates the versatility of the REDOR approach, with an emphasis on the practical considerations of experimental design and data interpretation.
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Affiliation(s)
- Lynette Cegelski
- Department of Chemistry, Stanford University, Stanford, CA 94305, USA.
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35
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Olsufyeva EN, Preobrazhenskaya MN. Glycopeptide antibiotic analogs efficient against vancomycin-resistant bacteria: a patent evaluation (WO2013022763). Expert Opin Ther Pat 2013; 23:1625-34. [PMID: 23972226 DOI: 10.1517/13543776.2013.831074] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The patent claims the preparation of vancomycin analogs equally active against bacterial strains that are primarily sensitive or resistant to this antibiotic. The pseudopeptide core of new compounds carries the amidine group that replaces the carboxamide linking group in the D ring-bearing amino acid residue of the glycopeptide. An elegant method of synthesis of amidine containing glycopeptides via thioamides was developed. The key glycopeptide thioamide analogs were prepared by total multistep synthesis. These analogs can be readily converted to the antibiotic's amidine as well as to alkylamidines, amidrazones, hydroxyamidines and similar analogs. The new analogs are capable of circumventing bacterial resistance derived from the D-Ala-D-Ala to D-Ala-D-Lac alteration - the mechanism operational in the resistant strains VanA and VanB. The interaction of the carboxamide, thioamide and amidine fragments of vancomycin analogs with the targets in resistant and sensitive bacteria was investigated. The novel compounds demonstrated potent activity against VanA-resistant bacteria Enterococcus faecalis (minimal inhibitory concentration = 0.3 - 0.6 μg/ml). However data on susceptible strains and resistant clinical isolates are lacking to further document the interest of the compounds. The results provide evidence for structural modifications that can improve the therapeutic efficacy of vancomycin, in particular, for treatment of vancomycin-resistant infections.
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Affiliation(s)
- Eugenia N Olsufyeva
- Gause Institute of New Antibiotics of the Russian Academy of Medical Sciences , Moscow , Russian Federation
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36
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In vivo studies suggest that induction of VanS-dependent vancomycin resistance requires binding of the drug to D-Ala-D-Ala termini in the peptidoglycan cell wall. Antimicrob Agents Chemother 2013; 57:4470-80. [PMID: 23836175 DOI: 10.1128/aac.00523-13] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
VanRS two-component regulatory systems are key elements required for the transcriptional activation of inducible vancomycin resistance genes in bacteria, but the precise nature of the ligand signal that activates these systems has remained undefined. Using the resistance system in Streptomyces coelicolor as a model, we have undertaken a series of in vivo studies which indicate that the VanS sensor kinase in VanB-type resistance systems is activated by vancomycin in complex with the d-alanyl-d-alanine (d-Ala-d-Ala) termini of cell wall peptidoglycan (PG) precursors. Complementation of an essential d-Ala-d-Ala ligase activity by constitutive expression of vanA encoding a bifunctional d-Ala-d-Ala and d-alanyl-d-lactate (d-Ala-d-Lac) ligase activity allowed construction of strains that synthesized variable amounts of PG precursors containing d-Ala-d-Ala. Assays quantifying the expression of genes under VanRS control showed that the response to vancomycin in these strains correlated with the abundance of d-Ala-d-Ala-containing PG precursors; strains producing a lower proportion of PG precursors terminating in d-Ala-d-Ala consistently exhibited a lower response to vancomycin. Pretreatment of wild-type cells with vancomycin or teicoplanin to saturate and mask the d-Ala-d-Ala binding sites in nascent PG also blocked the transcriptional response to subsequent vancomycin exposure, and desleucyl vancomycin, a vancomycin analogue incapable of interacting with d-Ala-d-Ala residues, failed to induce van gene expression. Activation of resistance by a vancomycin-d-Ala-d-Ala PG complex predicts a limit to the proportion of PG that can be derived from precursors terminating in d-Ala-d-Lac, a restriction also enforced by the bifunctional activity of the VanA ligase.
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37
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Structural and functional insights into caseinolytic proteases reveal an unprecedented regulation principle of their catalytic triad. Proc Natl Acad Sci U S A 2013; 110:11302-7. [PMID: 23798410 DOI: 10.1073/pnas.1219125110] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Caseinolytic proteases (ClpPs) are large oligomeric protein complexes that contribute to cell homeostasis as well as virulence regulation in bacteria. Although most organisms possess a single ClpP protein, some organisms encode two or more ClpP isoforms. Here, we elucidated the crystal structures of ClpP1 and ClpP2 from pathogenic Listeria monocytogenes and observe an unprecedented regulation principle by the catalytic triad. Whereas L. monocytogenes (Lm)ClpP2 is both structurally and functionally similar to previously studied tetradecameric ClpP proteins from Escherichia coli and Staphylococcus aureus, heptameric LmClpP1 features an asparagine in its catalytic triad. Mutation of this asparagine to aspartate increased the reactivity of the active site and led to the assembly of a tetradecameric complex. We analyzed the heterooligomeric complex of LmClpP1 and LmClpP2 via coexpression and subsequent labeling studies with natural product-derived probes. Notably, the LmClpP1 peptidase activity is stimulated 75-fold in the complex providing insights into heterooligomerization as a regulatory mechanism. Collectively, our data point toward different preferences for substrates and inhibitors of the two ClpP enzymes and highlight their structural and functional characteristics.
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38
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Kim SJ, Singh M, Preobrazhenskaya M, Schaefer J. Staphylococcus aureus peptidoglycan stem packing by rotational-echo double resonance NMR spectroscopy. Biochemistry 2013; 52:3651-9. [PMID: 23617832 PMCID: PMC3796188 DOI: 10.1021/bi4005039] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Staphylococcus aureus grown in the presence of an alanine-racemase inhibitor was labeled with d-[1-(13)C]alanine and l-[(15)N]alanine to characterize some details of the peptidoglycan tertiary structure. Rotational-echo double-resonance NMR of intact whole cells was used to measure internuclear distances between (13)C and (15)N of labeled amino acids incorporated in the peptidoglycan, and from those labels to (19)F of a glycopeptide drug specifically bound to the peptidoglycan. The observed (13)C-(15)N average distance of 4.1-4.4 Å between d- and l-alanines in nearest-neighbor peptide stems is consistent with a local, tightly packed, parallel-stem architecture for a repeating structural motif within the peptidoglycan of S. aureus.
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Affiliation(s)
- Sung Joon Kim
- Department of Chemistry and Biochemistry, Baylor University, Waco, TX 76706
| | - Manmilan Singh
- Department of Chemistry, Washington University, St. Louis, MO 63130
| | - Maria Preobrazhenskaya
- Gause Institute of New Antibiotics, Russian Academy of Medical Sciences, Moscow 119021, Russia
| | - Jacob Schaefer
- Department of Chemistry, Washington University, St. Louis, MO 63130
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39
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Kim SJ, Tanaka KSE, Dietrich E, Rafai Far A, Schaefer J. Locations of the hydrophobic side chains of lipoglycopeptides bound to the peptidoglycan of Staphylococcus aureus. Biochemistry 2013; 52:3405-14. [PMID: 23607653 DOI: 10.1021/bi400054p] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Glycopeptides whose aminosugars have been modified by attachment of hydrophobic side chains are frequently active against vancomycin-resistant microorganisms. We have compared the conformations of six such fluorinated glycopeptides (with side chains of varying length) complexed to cell walls labeled with d-[1-(13)C]alanine, [1-(13)C]glycine, and l-[ε-(15)N]lysine in whole cells of Staphylococcus aureus. The internuclear distances from (19)F of the bound drug to the (13)C and (15)N labels of the peptidoglycan, and to the natural abundance (31)P of lipid membranes and teichoic acids, were determined by rotational-echo double resonance NMR. The drugs did not dimerize, and their side chains did not form membrane anchors but instead became essential parts of secondary binding to pentaglycyl bridge segments of the cell-wall peptidoglycan.
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Affiliation(s)
- Sung Joon Kim
- Department of Chemistry and Biochemistry, Baylor University , Waco, Texas 76798, United States
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40
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Kim SJ, Singh M, Wohlrab A, Yu TY, Patti GJ, O’Connor RD, VanNieuwenhze M, Schaefer J. The isotridecanyl side chain of plusbacin-A3 is essential for the transglycosylase inhibition of peptidoglycan biosynthesis. Biochemistry 2013; 52:1973-9. [PMID: 23421534 PMCID: PMC3628776 DOI: 10.1021/bi4000222] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Plusbacin-A3 (pb-A3) is a cyclic lipodepsipeptide that exhibits antibacterial activity against multidrug-resistant Gram-positive pathogens. Plusbacin-A3 is thought not to enter the cell cytoplasm, and its lipophilic isotridecanyl side chain is presumed to insert into the membrane bilayer, thereby facilitating either lipid II binding or some form of membrane disruption. Analogues of pb-A3, [(2)H]pb-A3 and deslipo-pb-A3, were synthesized to test membrane insertion as a key to the mode of action. [(2)H]pb-A3 has an isotopically (2)H-labeled isopropyl subunit of the lipid side chain, and deslipo-pb-A3 is missing the isotridecanyl side chain. Both analogues have the pb-A3 core structure. The loss of antimicrobial activity in deslipo-pb-A3 showed that the isotridecanyl side chain is crucial for the mode of action of the drug. However, rotational-echo double-resonance nuclear magnetic resonance characterization of [(2)H]pb-A3 bound to [1-(13)C]glycine-labeled whole cells of Staphylococcus aureus showed that the isotridecanyl side chain does not insert into the lipid membrane but instead is found in the staphylococcal cell wall, positioned near the pentaglycyl cross-bridge of the cell-wall peptidoglycan. Addition of [(2)H]pb-A3 during the growth of S. aureus resulted in the accumulation of Park's nucleotide, consistent with the inhibition of the transglycosylation step of peptidoglycan biosynthesis.
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Affiliation(s)
- Sung Joon Kim
- Department of Chemistry and Biochemistry, Baylor University, Waco, TX 76798
| | - Manmilan Singh
- Department of Chemistry, Washington University, St. Louis, MO 63130
| | - Aaron Wohlrab
- Department of Chemistry, Indiana University, Bloomington, IN 47405
| | - Tsyr-Yan Yu
- Department of Chemistry, Washington University, St. Louis, MO 63130
| | - Gary J. Patti
- Department of Chemistry, Washington University, St. Louis, MO 63130
| | | | | | - Jacob Schaefer
- Department of Chemistry, Washington University, St. Louis, MO 63130
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41
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Uniformity of glycyl bridge lengths in the mature cell walls of fem mutants of methicillin-resistant Staphylococcus aureus. J Bacteriol 2013; 195:1421-7. [PMID: 23335411 DOI: 10.1128/jb.01471-12] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Peptidoglycan (PG) composition in intact cells of methicillin-resistant Staphylococcus aureus (MRSA) and its isogenic Fem mutants has been characterized by measuring the glycine content of PG bridge structures by solid-state nuclear magnetic resonance (NMR). The glycine content estimated from integrated intensities (rather than peak heights) in the cell walls of whole cells was increased by approximately 30% for the FemA mutant and was reduced by 25% for the FemB mutant relative to expected values for homogeneous structures. In contrast, the expected compositions were observed in isolated cell walls of the same mutants. For FemA mutant whole cells, the increase was due to the presence of triglycyl bridge PG units (confirmed directly by mass spectrometric analysis), which constituted 10% of the total PG. These species were coalesced in some sort of a lattice or aggregate with spatial proximity to other PG bridges. This result suggests that the triglycyl-bridged PG units form a PG-like structure that is not incorporated into the mature cell wall.
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42
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Jawla S, Ni QZ, Barnes A, Guss W, Daviso E, Herzfeld J, Griffin R, Temkin R. Continuously Tunable 250 GHz Gyrotron with a Double Disk Window for DNP-NMR Spectroscopy. JOURNAL OF INFRARED, MILLIMETER AND TERAHERTZ WAVES 2013; 34:42-52. [PMID: 23539422 PMCID: PMC3607393 DOI: 10.1007/s10762-012-9947-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
In this paper, we describe the design and experimental results from the rebuild of a 250 GHz gyrotron used for Dynamic Nuclear Polarization enhanced Nuclear Magnetic Resonance spectroscopy on a 380 MHz spectrometer. Tuning bandwidth of approximately 2 GHz is easily achieved at a fixed magnetic field of 9.24 T and a beam current of 95 mA producing an average output power of >10 W over the entire tuning band. This tube incorporates a double disk output sapphire window in order to maximize the transmission at 250.58 GHz. DNP Signal enhancement of >125 is achieved on a 13C-Urea sample using this gyrotron.
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Affiliation(s)
- Sudheer Jawla
- Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, MA-02139, USA
| | - Qing Zhe Ni
- Francis Bitter Magnet Lab and Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA-02139, USA
| | - Alexander Barnes
- Francis Bitter Magnet Lab and Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA-02139, USA
| | - William Guss
- Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, MA-02139, USA
| | - Eugenio Daviso
- Francis Bitter Magnet Lab and Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA-02139, USA
- Department of Chemistry, Brandies University, Waltham, MA-02454, USA
| | - Judith Herzfeld
- Department of Chemistry, Brandies University, Waltham, MA-02454, USA
| | - Robert Griffin
- Francis Bitter Magnet Lab and Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA-02139, USA
| | - Richard Temkin
- Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, MA-02139, USA
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Matsuoka S. [Structural study on small molecules in biological solid samples by using solid state NMR]. YAKUGAKU ZASSHI 2012; 132:969-78. [PMID: 23023412 DOI: 10.1248/yakushi.132.969] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Many small molecule drugs have molecular targets that are non-crystalline and insoluble biological matrices, such as proteins embedded in lipid membrane, cell membranes, and cell walls. To understand the action mechanisms, it is essential to determine the binding structure with atomic-level resolution. Although solution nuclear magnetic resonance (NMR) and X-ray crystallography have been used to determine molecular structures of cell membrane and membrane proteins, these methods are unable to reproduce the complexity of biological systems because either solubilization or crystallization of target molecules is requisite. For structural studies of insoluble non-crystalline biological samples, so-called "biological solids", high resolution distance measurements using solid-state NMR are indispensable techniques, of which rotational-echo double-resonance (REDOR) is one of the most widely used methods. In this paper, a brief introduction to REDOR NMR and its applications to structural studies on the antifungal amphotericin B-membrane phospholipid complex and a structural elucidation of photorespiration metabolites in plant cells without extraction or isolation is provided.
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Affiliation(s)
- Shigeru Matsuoka
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, Japan.
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Eirich J, Orth R, Sieber SA. Unraveling the protein targets of vancomycin in living S. aureus and E. faecalis cells. J Am Chem Soc 2011; 133:12144-53. [PMID: 21736328 DOI: 10.1021/ja2039979] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Vancomycin is a potent glycopeptide antibiotic that has evolved to specifically bind to the D-Ala-D-Ala dipeptide termini of nascent peptidoglycans. Although this mode of action is well established, several studies indicate that vancomycin and analogues exploit noncanonical target sites. In order to address all vancomycin targets in clinically relevant Staphylococcus aureus and Enterococcus faecalis strains we developed a series of small-molecule photoaffinity probes based on vancomycin. Proteomic profiling revealed the specific labeling of two previously unknown vancomycin targets that are likely to contribute to its antibiotic activity. The specific inhibition of the major staphylococcal autolysin Atl confirms previous observations that vancomycin alters S. aureus cell morphology by interaction with the autolytic machinery. Moreover, in E. faecalis the vancomycin photoprobe specifically binds to an ABC transporter protein, which likely impedes the uptake of essential nutrients such as sugars and peptides. The labeling of these two prominent membrane targets in living cells reveals a thus far unexplored mode of vancomycin binding and inhibition that could allow a rational design of variants with improved activity.
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Affiliation(s)
- Jürgen Eirich
- Center for Integrated Protein Science Munich CIPSM, Department of Chemistry, Institute of Advanced Studies IAS, Technische Universität München, Lichtenbergstrasse 4, 85747 Garching, Germany
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Nanni EA, Barnes AB, Matsuki Y, Woskov PP, Corzilius B, Griffin RG, Temkin RJ. Microwave field distribution in a magic angle spinning dynamic nuclear polarization NMR probe. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2011; 210:16-23. [PMID: 21382733 PMCID: PMC3081422 DOI: 10.1016/j.jmr.2011.02.001] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2010] [Revised: 02/01/2011] [Accepted: 02/01/2011] [Indexed: 05/05/2023]
Abstract
We present a calculation of the microwave field distribution in a magic angle spinning (MAS) probe utilized in dynamic nuclear polarization (DNP) experiments. The microwave magnetic field (B(1S)) profile was obtained from simulations performed with the High Frequency Structure Simulator (HFSS) software suite, using a model that includes the launching antenna, the outer Kel-F stator housing coated with Ag, the RF coil, and the 4mm diameter sapphire rotor containing the sample. The predicted average B(1S) field is 13μT/W(1/2), where S denotes the electron spin. For a routinely achievable input power of 5W the corresponding value is γ(S)B(1S)=0.84MHz. The calculations provide insights into the coupling of the microwave power to the sample, including reflections from the RF coil and diffraction of the power transmitted through the coil. The variation of enhancement with rotor wall thickness was also successfully simulated. A second, simplified calculation was performed using a single pass model based on Gaussian beam propagation and Fresnel diffraction. This model provided additional physical insight and was in good agreement with the full HFSS simulation. These calculations indicate approaches to increasing the coupling of the microwave power to the sample, including the use of a converging lens and fine adjustment of the spacing of the windings of the RF coil. The present results should prove useful in optimizing the coupling of microwave power to the sample in future DNP experiments. Finally, the results of the simulation were used to predict the cross effect DNP enhancement (ϵ) vs. ω(1S)/(2π) for a sample of (13)C-urea dissolved in a 60:40 glycerol/water mixture containing the polarizing agent TOTAPOL; very good agreement was obtained between theory and experiment.
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Affiliation(s)
- Emilio A Nanni
- Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
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Crane CM, Pierce JG, Leung SSF, Tirado-Rives J, Jorgensen WL, Boger DL. Synthesis and evaluation of selected key methyl ether derivatives of vancomycin aglycon. J Med Chem 2010; 53:7229-35. [PMID: 20853900 DOI: 10.1021/jm100946e] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A select series of methyl ether derivatives of vancomcyin aglycon were prepared and examined for antimicrobial activity against vancomycin-sensitive Staphylococcus aureus and vancomycin-resistant Enterococci faecalis as well as their binding affinity for D-Ala-D-Ala and D-Ala-D-Lac. The intent of the study was to elucidate the role selected key methyl groups may play in the improvement of the in vitro antimicrobial profile of the tetra methyl ether derivative of vancomycin aglycon against vancomycin-resistant Enterococci faecalis previously reported. In these studies, methodology for selective derivatization of the A-, B-, and D-ring was developed that defines the relative reactivity of the four phenols of vancomycin aglycon, providing a foundation for future efforts for site-directed modification of the vancomycin aglycon core.
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Affiliation(s)
- Christine M Crane
- Department of Chemistry and the Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, USA
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Caporini MA, Bajaj VS, Veshtort M, Fitzpatrick A, MacPhee CE, Vendruscolo M, Dobson CM, Griffin RG. Accurate determination of interstrand distances and alignment in amyloid fibrils by magic angle spinning NMR. J Phys Chem B 2010; 114:13555-61. [PMID: 20925357 PMCID: PMC2959142 DOI: 10.1021/jp106675h] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Amyloid fibrils are structurally ordered aggregates of proteins whose formation is associated with many neurodegenerative and other diseases. For that reason, their high-resolution structures are of considerable interest and have been studied using a wide range of techniques, notably electron microscopy, X-ray diffraction, and magic angle spinning (MAS) NMR. Because of the excellent resolution in the spectra, MAS NMR is uniquely capable of delivering site-specific, atomic resolution information about all levels of amyloid structure: (1) the monomer, which packs into several (2) protofilaments that in turn associate to form a (3) fibril. Building upon our high-resolution structure of the monomer of an amyloid-forming peptide from transthyretin (TTR(105-115)), we introduce single 1-(13)C labeled amino acids at seven different sites in the peptide and measure intermolecular carbonyl-carbonyl distances with an accuracy of ~0.11 A. Our results conclusively establish a parallel, in register, topology for the packing of this peptide into a β-sheet and provide constraints essential for the determination of an atomic resolution structure of the fibril. Furthermore, the approach we employ, based on a combination of a double-quantum filtered variant of the DRAWS recoupling sequence and multispin numerical simulations in SPINEVOLUTION, is general and should be applicable to a wide range of systems.
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Affiliation(s)
- Marc A Caporini
- Francis Bitter Magnet Laboratory and Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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48
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Affiliation(s)
- Jed F Fisher
- Department of Chemistry and Biochemistry, 423 Nieuwland Science Hall, Notre Dame, Indiana 46556-5670, USA
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49
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Crane CM, Boger DL. Synthesis and evaluation of vancomycin aglycon analogues that bear modifications in the N-terminal D-leucyl amino acid. J Med Chem 2010; 52:1471-6. [PMID: 19209892 DOI: 10.1021/jm801549b] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The synthesis and biological evaluation of a series of vancomycin aglycon analogues bearing alternative residue 1 N-methyl-D-amino acids are described. The analogues were prepared to define whether H-bonding d-amino acids could improve the affinity for the model ligands N,N'-Ac(2)-L-Lys-D-Ala-D-Ala (2) and N,N'-Ac(2)-L-Lys-D-Ala-D-Lac (3) and improve antimicrobial activity against vancomycin-sensitive or vancomycin-resistant bacteria. Additionally, a series of analogues with appended nucleophiles (hydrazines and amines) on the residue 1 D-amino acids are described that were examined for their ability to react with the C-terminal ester of 3, forming a covalent attachment of L-Lys-D-Ala to the natural product analogues.
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Affiliation(s)
- Christine M Crane
- Department of Chemistry, The Scripps Research Institute, La Jolla, California 92037, USA
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50
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Reid CW, Fulton KM, Twine SM. Never take candy from a stranger: the role of the bacterial glycome in host–pathogen interactions. Future Microbiol 2010; 5:267-88. [DOI: 10.2217/fmb.09.103] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
With the comprehensive study and complete sequencing of the Haemophilus influenzae genome in 1995 came the term ‘genomics’ and the beginning of the ‘omics’ era. Since this time, several analogous fields, such as transcriptomics and proteomics, have emerged. While growth and advancement in these fields have increased understanding of microbial virulence, the study of bacterial glycomes is still in its infancy and little is known concerning their role in host–pathogen interactions. Bacterial glycomics is challenging owing to the diversity of glyco-conjugate molecules, vast array of unusual sugars and limited number of analytical approaches available. However, recent advances in glycomics technologies offer the potential for exploration and characterization of both the structures and functions of components of bacterial glycomes in a systematic manner. Such characterization is a prerequisite for discerning the role of bacterial glycans in the interaction between host defences and bacterial virulence factors.
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Affiliation(s)
- Christopher W Reid
- National Research Council – Institute for Biological Science, Ottawa, Ontario, K1A 0R6, Canada
| | - Kelly M Fulton
- National Research Council – Institute for Biological Science, Ottawa, Ontario, K1A 0R6, Canada
| | - Susan M Twine
- National Research Council – Institute for Biological Science, Ottawa, Ontario, K1A 0R6, Canada
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