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Moussa AY. Endophytes: a uniquely tailored source of potential antibiotic adjuvants. Arch Microbiol 2024; 206:207. [PMID: 38581477 PMCID: PMC10998792 DOI: 10.1007/s00203-024-03891-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2023] [Revised: 02/06/2024] [Accepted: 02/08/2024] [Indexed: 04/08/2024]
Abstract
Multidrug microbial resistance is risking an annual loss of more than 10 million people' lives by 2050. Solutions include the rational use of antibiotics and the use of drugs that reduce resistance or completely obliterate them. Here endophytes come to play due to their high-yield production and inherent nature to produce antimicrobial molecules. Around 40%, 45% and 17% of antibacterial agents were obtained from fungi, actinomycetes, and bacteria, respectively, whose secondary metabolites revealed effectiveness against resistant microbes such as MRSA, MRSE, and Shigella flexneri. Endophyte's role was not confined to bactericidal effect but extended to other mechanisms against MDR microbes, among which was the adjuvant role or the "magic bullets". Scarce focus was given to antibiotic adjuvants, and many laboratories today just screen for the antimicrobial activity without considering combinations with traditional antibiotics, which means real loss of promising resistance combating molecules. While some examples of synthetic adjuvants were introduced in the last decade, the number is still far from covering the disused antibiotics and restoring them back to clinical use. The data compiled in this article demonstrated the significance of quorum sensing as a foreseen mechanism for adjuvants from endophytes secondary metabolites, which call for urgent in-depth studies of their molecular mechanisms. This review, comprehensively and for the first time, sheds light on the significance of endophytes secondary metabolites in solving AMR problem as AB adjuvants.
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Affiliation(s)
- Ashaimaa Y Moussa
- Department of Pharmacognosy, Faculty of Pharmacy, Ain-Shams University, African Union Organization Street, Abbassia, Cairo, 11566, Egypt.
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2
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Dhanda G, Acharya Y, Haldar J. Antibiotic Adjuvants: A Versatile Approach to Combat Antibiotic Resistance. ACS OMEGA 2023; 8:10757-10783. [PMID: 37008128 PMCID: PMC10061514 DOI: 10.1021/acsomega.3c00312] [Citation(s) in RCA: 18] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Accepted: 02/21/2023] [Indexed: 06/13/2023]
Abstract
The problem of antibiotic resistance is on the rise, with multidrug-resistant strains emerging even to the last resort antibiotics. The drug discovery process is often stalled by stringent cut-offs required for effective drug design. In such a scenario, it is prudent to delve into the varying mechanisms of resistance to existing antibiotics and target them to improve antibiotic efficacy. Nonantibiotic compounds called antibiotic adjuvants which target bacterial resistance can be used in combination with obsolete drugs for an improved therapeutic regime. The field of "antibiotic adjuvants" has gained significant traction in recent years where mechanisms other than β-lactamase inhibition have been explored. This review discusses the multitude of acquired and inherent resistance mechanisms employed by bacteria to resist antibiotic action. The major focus of this review is how to target these resistance mechanisms by the use of antibiotic adjuvants. Different types of direct acting and indirect resistance breakers are discussed including enzyme inhibitors, efflux pump inhibitors, inhibitors of teichoic acid synthesis, and other cellular processes. The multifaceted class of membrane-targeting compounds with poly pharmacological effects and the potential of host immune-modulating compounds have also been reviewed. We conclude with providing insights about the existing challenges preventing clinical translation of different classes of adjuvants, especially membrane-perturbing compounds, and a framework about the possible directions which can be pursued to fill this gap. Antibiotic-adjuvant combinatorial therapy indeed has immense potential to be used as an upcoming orthogonal strategy to conventional antibiotic discovery.
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Affiliation(s)
- Geetika Dhanda
- Antimicrobial
Research Laboratory, New Chemistry Unit and School of Advanced
Materials, Jawaharlal Nehru Centre for Advanced
Scientific Research (JNCASR), Jakkur, Bengaluru 560064, Karnataka, India
| | - Yash Acharya
- Antimicrobial
Research Laboratory, New Chemistry Unit and School of Advanced
Materials, Jawaharlal Nehru Centre for Advanced
Scientific Research (JNCASR), Jakkur, Bengaluru 560064, Karnataka, India
| | - Jayanta Haldar
- Antimicrobial
Research Laboratory, New Chemistry Unit and School of Advanced
Materials, Jawaharlal Nehru Centre for Advanced
Scientific Research (JNCASR), Jakkur, Bengaluru 560064, Karnataka, India
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3
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Yarlagadda V, Medina R, Wright GD. Venturicidin A, A Membrane-active Natural Product Inhibitor of ATP synthase Potentiates Aminoglycoside Antibiotics. Sci Rep 2020; 10:8134. [PMID: 32424122 PMCID: PMC7235042 DOI: 10.1038/s41598-020-64756-0] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Accepted: 04/16/2020] [Indexed: 12/12/2022] Open
Abstract
Despite the remarkable advances due to the discovery and development of antimicrobials agents, infectious diseases remain the second leading cause of death worldwide. This fact underlines the importance of developing new therapeutic strategies to address the widespread antibiotic resistance, which is the major contributing factor for clinical failures of the current therapeutics. In a screen for antibiotic adjuvants, we identified a natural product from actinomycetes, venturicidin A (VentA), that potentiates the aminoglycoside antibiotic gentamicin against multidrug-resistant clinical isolates of Staphylococcus, Enterococcus, and Pseudomonas aeruginosa. Furthermore, the combination of gentamicin and VentA was bactericidal and rapidly eradicated methicillin-resistant S. aureus (MRSA). The molecular mechanism of gentamicin potentiation activity is attributed to uncoupling of ATP synthesis by VentA from electron transport presumably by blocking the proton flow through ATP synthase, which results in an elevated concentration of extracellular protons and subsequent anticipated raise in gentamicin uptake. The disruption of the proton flux was characterized by perturbed membrane potential in MRSA. These results demonstrate that inhibition of ATP synthase along with the subsequent membrane dysregulation, as shown here with VentA, complements aminoglycoside antibiotics against MDR bacteria, and that this approach may be employed to combat bacterial resistance.
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Affiliation(s)
- Venkateswarlu Yarlagadda
- David Braley Centre for Antibiotic Discovery, M.G. DeGroote Institute for Infectious Disease Research, Department of Biochemistry and Biomedical Sciences, DeGroote School of Medicine, McMaster University, 1280 Main Street West, Hamilton, Ontario, L8S 4K1, Canada
| | - Ricardo Medina
- Department of Microbiology, Central University of Las Villas, Santa Clara, Villa Clara, Cuba
| | - Gerard D Wright
- David Braley Centre for Antibiotic Discovery, M.G. DeGroote Institute for Infectious Disease Research, Department of Biochemistry and Biomedical Sciences, DeGroote School of Medicine, McMaster University, 1280 Main Street West, Hamilton, Ontario, L8S 4K1, Canada.
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Green KD, Punetha A, Hou C, Garneau-Tsodikova S, Tsodikov OV. Probing the Robustness of Inhibitors of Tuberculosis Aminoglycoside Resistance Enzyme Eis by Mutagenesis. ACS Infect Dis 2019; 5:1772-1778. [PMID: 31433614 DOI: 10.1021/acsinfecdis.9b00228] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Each year, millions of people worldwide contract tuberculosis (TB), the deadliest infection. The spread of infections with drug-resistant strains of Mycobacterium tuberculosis (Mtb) that are refractory to treatment poses a major global challenge. A major cause of resistance to antitubercular drugs of last resort, aminoglycosides, is overexpression of the Eis (enhanced intracellular survival) enzyme of Mtb, which inactivates aminoglycosides by acetylating them. We showed previously that this inactivation of aminoglycosides could be overcome by our recently reported Eis inhibitors that are currently in development as potential aminoglycoside adjunctive therapeutics against drug-resistant TB. To interrogate the robustness of the Eis inhibitors, we investigated the enzymatic activity of Eis and its inhibition by Eis inhibitors from three different structural families for nine single-residue mutants of Eis, including those found in the clinic. Three engineered mutations of the substrate binding site, D26A, W36A, and F84A, abolished inhibitor binding while compromising Eis enzymatic activity 2- to 3-fold. All other Eis mutants, including clinically observed ones, were potently inhibited by at least one inhibitor. This study helps position us one step ahead of Mtb resistance to Eis inhibitors as they are being developed for TB therapy.
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Affiliation(s)
- Keith D. Green
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, 789 South Limestone Street, Lexington, Kentucky 40536-0596, United States
| | - Ankita Punetha
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, 789 South Limestone Street, Lexington, Kentucky 40536-0596, United States
| | - Caixia Hou
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, 789 South Limestone Street, Lexington, Kentucky 40536-0596, United States
| | - Sylvie Garneau-Tsodikova
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, 789 South Limestone Street, Lexington, Kentucky 40536-0596, United States
| | - Oleg V. Tsodikov
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, 789 South Limestone Street, Lexington, Kentucky 40536-0596, United States
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5
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Drug combinations: a strategy to extend the life of antibiotics in the 21st century. Nat Rev Microbiol 2019; 17:141-155. [PMID: 30683887 DOI: 10.1038/s41579-018-0141-x] [Citation(s) in RCA: 455] [Impact Index Per Article: 91.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2018] [Accepted: 11/22/2018] [Indexed: 01/03/2023]
Abstract
Antimicrobial resistance threatens a resurgence of life-threatening bacterial infections and the potential demise of many aspects of modern medicine. Despite intensive drug discovery efforts, no new classes of antibiotics have been developed into new medicines for decades, in large part owing to the stringent chemical, biological and pharmacological requisites for effective antibiotic drugs. Combinations of antibiotics and of antibiotics with non-antibiotic activity-enhancing compounds offer a productive strategy to address the widespread emergence of antibiotic-resistant strains. In this Review, we outline a theoretical and practical framework for the development of effective antibiotic combinations.
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Stogios PJ, Cox G, Spanogiannopoulos P, Pillon MC, Waglechner N, Skarina T, Koteva K, Guarné A, Savchenko A, Wright GD. Rifampin phosphotransferase is an unusual antibiotic resistance kinase. Nat Commun 2016; 7:11343. [PMID: 27103605 PMCID: PMC4844700 DOI: 10.1038/ncomms11343] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Accepted: 03/15/2016] [Indexed: 11/11/2022] Open
Abstract
Rifampin (RIF) phosphotransferase (RPH) confers antibiotic resistance by conversion of RIF and ATP, to inactive phospho-RIF, AMP and Pi. Here we present the crystal structure of RPH from Listeria monocytogenes (RPH-Lm), which reveals that the enzyme is comprised of three domains: two substrate-binding domains (ATP-grasp and RIF-binding domains); and a smaller phosphate-carrying His swivel domain. Using solution small-angle X-ray scattering and mutagenesis, we reveal a mechanism where the swivel domain transits between the spatially distinct substrate-binding sites during catalysis. RPHs are previously uncharacterized dikinases that are widespread in environmental and pathogenic bacteria. These enzymes are members of a large unexplored group of bacterial enzymes with substrate affinities that have yet to be fully explored. Such an enzymatically complex mechanism of antibiotic resistance augments the spectrum of strategies used by bacteria to evade antimicrobial compounds.
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Affiliation(s)
- Peter J. Stogios
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Ontario, Canada M5G 1L6
| | - Georgina Cox
- M.G. DeGroote Institute for Infectious Disease Research, Department of Biochemistry and Biomedical Sciences, McMaster University, 1280 Main St W, Hamilton, Ontario, Canada L8S 4K1
| | - Peter Spanogiannopoulos
- M.G. DeGroote Institute for Infectious Disease Research, Department of Biochemistry and Biomedical Sciences, McMaster University, 1280 Main St W, Hamilton, Ontario, Canada L8S 4K1
| | - Monica C. Pillon
- Department of Biochemistry and Biomedical Sciences, McMaster University, 1280 Main St W, Hamilton, Ontario, Canada L8S 4K1
| | - Nicholas Waglechner
- M.G. DeGroote Institute for Infectious Disease Research, Department of Biochemistry and Biomedical Sciences, McMaster University, 1280 Main St W, Hamilton, Ontario, Canada L8S 4K1
| | - Tatiana Skarina
- M.G. DeGroote Institute for Infectious Disease Research, Department of Biochemistry and Biomedical Sciences, McMaster University, 1280 Main St W, Hamilton, Ontario, Canada L8S 4K1
| | - Kalinka Koteva
- M.G. DeGroote Institute for Infectious Disease Research, Department of Biochemistry and Biomedical Sciences, McMaster University, 1280 Main St W, Hamilton, Ontario, Canada L8S 4K1
| | - Alba Guarné
- Department of Biochemistry and Biomedical Sciences, McMaster University, 1280 Main St W, Hamilton, Ontario, Canada L8S 4K1
| | - Alexei Savchenko
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Ontario, Canada M5G 1L6
| | - Gerard D. Wright
- M.G. DeGroote Institute for Infectious Disease Research, Department of Biochemistry and Biomedical Sciences, McMaster University, 1280 Main St W, Hamilton, Ontario, Canada L8S 4K1
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7
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Kunzmann MH, Bach NC, Bauer B, Sieber SA. α-Methylene-γ-butyrolactones attenuate Staphylococcus aureus virulence by inhibition of transcriptional regulation. Chem Sci 2014. [DOI: 10.1039/c3sc52228h] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
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8
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Shi K, Caldwell SJ, Fong DH, Berghuis AM. Prospects for circumventing aminoglycoside kinase mediated antibiotic resistance. Front Cell Infect Microbiol 2013; 3:22. [PMID: 23805415 PMCID: PMC3691515 DOI: 10.3389/fcimb.2013.00022] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2013] [Accepted: 06/04/2013] [Indexed: 01/10/2023] Open
Abstract
Aminoglycosides are a class of antibiotics with a broad spectrum of antimicrobial activity. Unfortunately, resistance in clinical isolates is pervasive, rendering many aminoglycosides ineffective. The most widely disseminated means of resistance to this class of antibiotics is inactivation of the drug by aminoglycoside-modifying enzymes (AMEs). There are two principal strategies to overcoming the effects of AMEs. The first approach involves the design of novel aminoglycosides that can evade modification. Although this strategy has yielded a number of superior aminoglycoside variants, their efficacy cannot be sustained in the long term. The second approach entails the development of molecules that interfere with the mechanism of AMEs such that the activity of aminoglycosides is preserved. Although such a molecule has yet to enter clinical development, the search for AME inhibitors has been greatly facilitated by the wealth of structural information amassed in recent years. In particular, aminoglycoside phosphotransferases or kinases (APHs) have been studied extensively and crystal structures of a number of APHs with diverse regiospecificity and substrate specificity have been elucidated. In this review, we present a comprehensive overview of the available APH structures and recent progress in APH inhibitor development, with a focus on the structure-guided strategies.
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Affiliation(s)
- Kun Shi
- Groupe de Recherche Axé sur la Structure des Protéines, Department of Biochemistry, McGill UniversityMontreal, QC, Canada
| | - Shane J. Caldwell
- Groupe de Recherche Axé sur la Structure des Protéines, Department of Biochemistry, McGill UniversityMontreal, QC, Canada
| | - Desiree H. Fong
- Groupe de Recherche Axé sur la Structure des Protéines, Department of Biochemistry, McGill UniversityMontreal, QC, Canada
| | - Albert M. Berghuis
- Groupe de Recherche Axé sur la Structure des Protéines, Department of Biochemistry, McGill UniversityMontreal, QC, Canada
- Department of Microbiology and Immunology, McGill UniversityMontreal, QC, Canada
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9
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Thermodynamical properties of protein kinase with adenine inhibitors. CHINESE SCIENCE BULLETIN-CHINESE 2013. [DOI: 10.1007/s11434-012-5611-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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10
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Chaudhary M, Kesava Naidu G, Kumar S, Payasi A. Comparative antibacterial activity of a novel semisynthetic antibiotic: etimicin sulphate and other aminoglycosides. World J Microbiol Biotechnol 2012; 28:3365-71. [PMID: 22983905 DOI: 10.1007/s11274-012-1148-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2012] [Accepted: 08/06/2012] [Indexed: 11/25/2022]
Abstract
Etimicin is a novel fourth generation semisynthetic aminoglycoside. It has good antimicrobial activity against both gram-positive and gram-negative bacterial infections and also against aminoglycoside resistant strains. In the present study, in vitro antibacterial activity of etimicin was determined by minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC) and time kill curve tests against type strains and 407 clinical isolates (obtained in a surveillance study), in comparison to other aminoglycosides. Test results revealed that etimicin has potential antimicrobial activity and MIC, MBC values for etimicin were low compared to other aminoglycosides. In MBC test etimicin has exhibited potential bactericidal effect ranging from 0.25 to 2 mg/L. The time kill-curve study further demonstrated the rapid, concentration dependent killing and comparative study showed etimicin to exhibit long and effective bactericidal activity over amikacin. The interesting fact is that most of the tested aminoglycoside resistant clinical isolates were susceptible to etimicin. In view of its potent in vitro antibacterial activity and efficacy profiles, it can be concluded that etimicin can be a potent injectable agent for the treatment of severe bacterial infections.
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Affiliation(s)
- Manu Chaudhary
- Venus Medicine Research Centre, Hill Top Industrial Estate, Bhatoli Kalan, Baddi, H.P., 173205, India.
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11
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Caldwell SJ, Berghuis AM. Small-angle X-ray scattering analysis of the bifunctional antibiotic resistance enzyme aminoglycoside (6') acetyltransferase-ie/aminoglycoside (2'') phosphotransferase-ia reveals a rigid solution structure. Antimicrob Agents Chemother 2012; 56:1899-906. [PMID: 22290965 PMCID: PMC3318351 DOI: 10.1128/aac.06378-11] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2011] [Accepted: 01/20/2012] [Indexed: 11/20/2022] Open
Abstract
Aminoglycoside (6') acetyltransferase-Ie/aminoglycoside (2″) phosphotransferase-Ia [AAC(6')-Ie/APH(2″)-Ia] is one of the most problematic aminoglycoside resistance factors in clinical pathogens, conferring resistance to almost every aminoglycoside antibiotic available to modern medicine. Despite 3 decades of research, our understanding of the structure of this bifunctional enzyme remains limited. We used small-angle X-ray scattering (SAXS) to model the structure of this bifunctional enzyme in solution and to study the impact of substrate binding on the enzyme. It was observed that the enzyme adopts a rigid conformation in solution, where the N-terminal AAC domain is fixed to the C-terminal APH domain and not loosely tethered. The addition of acetyl-coenzyme A, coenzyme A, GDP, guanosine 5'-[β,γ-imido]triphosphate (GMPPNP), and combinations thereof to the protein resulted in only modest changes to the radius of gyration (R(G)) of the enzyme, which were not consistent with any large changes in enzyme structure upon binding. These results imply some selective advantage to the bifunctional enzyme beyond coexpression as a single polypeptide, likely linked to an improvement in enzymatic properties. We propose that the rigid structure contributes to improved electrostatic steering of aminoglycoside substrates toward the two active sites, which may provide such an advantage.
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Affiliation(s)
| | - Albert M. Berghuis
- Department of Biochemistry
- Department of Microbiology and Immunology, Groupe de Recherche Axé sur la Structure des Protéines, McGill University, Montreal, Quebec, Canada
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12
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Vong K, Auclair K. Understanding and overcoming aminoglycoside resistance caused by N-6'-acetyltransferase. MEDCHEMCOMM 2012; 3:397-407. [PMID: 28018574 PMCID: PMC5179255 DOI: 10.1039/c2md00253a] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Aminoglycosides occupy a special niche amongst antibiotics in part because of their broad spectrum of action. Bacterial resistance is however menacing to render these drugs obsolete. A significant amount of work has been devoted to understand and overcome aminoglycoside resistance. This mini-review will discuss aminoglycoside-modifying enzymes (AMEs), with a special emphasis on the efforts to comprehend and block resistance caused by aminoglycoside 6'-N-acetyltransferase (AAC(6')).
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Affiliation(s)
- Kenward Vong
- Department of Chemistry, McGill University, 801 Sherbrooke Street West, Montréal, Québec, Canada H3A 2K6
| | - Karine Auclair
- Department of Chemistry, McGill University, 801 Sherbrooke Street West, Montréal, Québec, Canada H3A 2K6
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13
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A Small Molecule Discrimination Map of the Antibiotic Resistance Kinome. ACTA ACUST UNITED AC 2011; 18:1591-601. [DOI: 10.1016/j.chembiol.2011.10.018] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2011] [Revised: 10/21/2011] [Accepted: 10/24/2011] [Indexed: 12/21/2022]
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14
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Green KD, Chen W, Houghton JL, Fridman M, Garneau-Tsodikova S. Exploring the substrate promiscuity of drug-modifying enzymes for the chemoenzymatic generation of N-acylated aminoglycosides. Chembiochem 2010; 11:119-26. [PMID: 19899089 DOI: 10.1002/cbic.200900584] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2009] [Indexed: 11/11/2022]
Abstract
Aminoglycosides are broad-spectrum antibiotics commonly used for the treatment of serious bacterial infections. Decades of clinical use have led to the widespread emergence of bacterial resistance to this family of drugs limiting their efficacy in the clinic. Here, we report the development of a methodology that utilizes aminoglycoside acetyltransferases (AACs) and unnatural acyl coenzyme A analogues for the chemoenzymatic generation of N-acylated aminoglycoside analogues. Generation of N-acylated aminoglycosides is followed by a simple qualitative test to assess their potency as potential antibacterials. The studied AACs (AAC(6')-APH(2'') and AAC(3)-IV) show diverse substrate promiscuity towards a variety of aminoglycosides as well as acyl coenzyme A derivatives. The enzymes were also used for the sequential generation of homo- and hetero-di-N-acylated aminoglycosides. Following the clinical success of the N-acylated amikacin and arbekacin, our chemoenzymatic approach offers access to regioselectively N-acylated aminoglycosides in quantities that allow testing of the antibacterial potential of the synthetic analogues making it possible to decide which molecules will be worth synthesizing on a larger scale.
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Affiliation(s)
- Keith D Green
- Life Sciences Institute, University of Michigan, 210 Washtenaw Ave., Ann Arbor, MI 48109, USA
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15
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Zhang W, Fisher JF, Mobashery S. The bifunctional enzymes of antibiotic resistance. Curr Opin Microbiol 2009; 12:505-11. [PMID: 19615931 DOI: 10.1016/j.mib.2009.06.013] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2009] [Accepted: 06/09/2009] [Indexed: 11/29/2022]
Abstract
The evolutionary union of two genes--each encoding proteins of complementary enzymatic activity--into a single gene so as to allow the coordinated expression of these activities as a fusion polypeptide, is an increasingly recognized biological occurrence. The result of this genetic union is the bifunctional enzyme. This fusion of separate catalytic activities into a single protein, whose gene is regulated by a single promoter, is seen especially where the coordinated expression of the separate activities is highly desirable. Increasingly, a circumstance driving the evolution of the bifunctional enzyme in bacteria is the resistance response of bacteria to antibiotic chemotherapy. We summarize the knowledge on bifunctional antibiotic-resistance enzymes, as possible harbingers of clinically significant resistance mechanisms of the future.
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Affiliation(s)
- Weilie Zhang
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA
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16
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Li CR, Yang XY, Lou RH, Zhang WX, Wang YM, Yuan M, Li Y, Chen HZ, Hong B, Sun CH, Zhao LX, Li ZR, Jiang JD, You XF. In vitro antibacterial activity of vertilmicin and its susceptibility to modifications by the recombinant AAC6'-APH2'' enzyme. Antimicrob Agents Chemother 2008; 52:3875-82. [PMID: 18710917 PMCID: PMC2573110 DOI: 10.1128/aac.01400-07] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2007] [Revised: 02/23/2008] [Accepted: 08/03/2008] [Indexed: 11/20/2022] Open
Abstract
Vertilmicin is a new semisynthetic aminoglycoside with a structure similar to that of netilmicin except for a methyl group at the C-6' position. In the present study, the in vitro antibacterial activity of vertilmicin was studied, and its susceptibility to modifications by the recombinant aminoglycoside bifunctional modifying enzyme AAC(6')-APH(2'') was compared with those of verdamicin and netilmicin. A total of 1,185 clinical isolates collected from hospitals in Beijing between 2000 and 2001 were subjected to the in vitro antibacterial activity evaluations, including MIC, minimum bactericidal concentration (MBC), and time-kill curve tests. The MICs were evaluated in non-gentamicin-resistant (gentamicin-susceptible and gentamicin-intermediate) strains and gentamicin-resistant strains, respectively. For most of the non-gentamicin-resistant bacteria (except for the isolates of Pseudomonas spp.), the MIC(90)s of vertilmicin were in the range of 0.5 to 8 microg/ml, comparable to those of the reference aminoglycosides. For the gentamicin-resistant isolates, the three semisynthetic aminoglycosides (vertilmicin, netilmicin, and amikacin) demonstrated low MIC(50)s and/or MIC(90)s, as well as high percent susceptibility values. Among the study drugs, vertilmicin showed the lowest MIC(90)s, 16 microg/ml, for the gram-positive gentamicin-resistant isolates of Staphylococcus aureus and Staphylococcus epidermidis. Meanwhile, vertilmicin was a potent bactericidal agent, with MBC/MIC ratios in the range of 1 to 2 for Escherichia coli, Klebsiella pneumoniae, and S. aureus and 1 to 4 for S. epidermidis. The time-kill curve determination further demonstrated that this effect was rapid and concentration dependent. In evaluations of susceptibility to modifications by the recombinant AAC(6')-APH(2'') with maximum rate of metabolism/K(m) measurements, vertilmicin exhibited susceptibilities to both acetylation and phosphorylation lower than those of netilmicin and verdamicin.
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Affiliation(s)
- Cong-Ran Li
- Laboratory of Pharmacology, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
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Abstract
Researchers in the post-genome era are confronted with the daunting task of assigning structure and function to tens of thousands of encoded proteins. To realize this goal, new technologies are emerging for the analysis of protein function on a global scale, such as activity-based protein profiling (ABPP), which aims to develop active site-directed chemical probes for enzyme analysis in whole proteomes. For the pursuit of such chemical proteomic technologies, it is helpful to derive inspiration from protein-reactive natural products. Natural products use a remarkably diverse set of mechanisms to covalently modify enzymes from distinct mechanistic classes, thus providing a wellspring of chemical concepts that can be exploited for the design of active-site-directed proteomic probes. Herein, we highlight several examples of protein-reactive natural products and illustrate how their mechanisms of action have influenced and continue to shape the progression of chemical proteomic technologies like ABPP.
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Affiliation(s)
- Carmen Drahl
- Department of Chemistry, Princeton University, Princeton, NJ 08544, USA
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Nagoshi C, Shiota S, Kuroda T, Hatano T, Yoshida T, Kariyama R, Tsuchiya T. Synergistic Effect of [10]-Gingerol and Aminoglycosides against Vancomycin-Resistant Enterococci (VRE). Biol Pharm Bull 2006; 29:443-7. [PMID: 16508142 DOI: 10.1248/bpb.29.443] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
An extract from ginger (root of Zingiber officinale) reduced the minimum inhibitory concentrations (MICs) of aminoglycosides in vancomycin-resistant enterococci (VRE). The effective compound was isolated and identified as [10]-gingerol. In the presence of [10]-gingerol at 1/10 concentration of its own MIC, the MIC of arbekacin was lowered by 1/32 to 1/16. [10]-Gingerol also reduced the MICs of other aminoglycosides, and of bacitracin and polymixin B, but not of other antimicrobial agents tested. Because [10]-gingerol reduced the MICs of several aminoglycosides both in strains possessing or lacking aminoglycoside-modification enzymes, it seems that the effect of [10]-gingerol is not related to these enzymes, which mainly confer bacterial resistance against aminoglycosides. It seemed that a detergent-like effect of [10]-gingerol potentiated the antimicrobial activity of the aminoglycosides. In fact, some detergents such as sodium dodecyl sulfate (SDS) and Triton X-100 reduced the MICs of aminoglycosides, bacitracin and polymixin B in VRE. Since the intrinsic resistance to aminoglycosides in enterococci is due to low level of entry of the drugs into the cells, increase in the membrane permeability caused by [10]-gingerol will enhance the influx of aminoglycosides into enterococcal cells.
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Affiliation(s)
- Chihiro Nagoshi
- Department of Molecular Microbiology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Tsushima, Japan
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Affiliation(s)
- Sophie Magnet
- Department of Biochemistry, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, New York 10461, USA
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Boehr DD, Jenkins SI, Wright GD. The molecular basis of the expansive substrate specificity of the antibiotic resistance enzyme aminoglycoside acetyltransferase-6'-aminoglycoside phosphotransferase-2". The role of ASP-99 as an active site base important for acetyl transfer. J Biol Chem 2003; 278:12873-80. [PMID: 12566434 DOI: 10.1074/jbc.m211680200] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The most frequent determinant of aminoglycoside antibiotic resistance in Gram-positive bacterial pathogens is a bifunctional enzyme, aminoglycoside acetyltransferase-6'-aminoglycoside phosphotransferase-2" (AAC(6')- aminoglycoside phosphotransferase-2", capable of modifying a wide selection of clinically relevant antibiotics through its acetyltransferase and kinase activities. The aminoglycoside acetyltransferase domain of the enzyme, AAC(6')-Ie, is the only member of the large AAC(6') subclass known to modify fortimicin A and catalyze O-acetylation. We have demonstrated through solvent isotope, pH, and site-directed mutagenesis effects that Asp-99 is responsible for the distinct abilities of AAC(6')-Ie. Moreover, we have demonstrated that small planar molecules such as 1-(bromomethyl)phenanthrene can inactivate the enzyme through covalent modification of this residue. Thus, Asp-99 acts as an active site base in the molecular mechanism of AAC(6')-Ie. The prominent role of this residue in aminoglycoside modification can be exploited as an anchoring site for the development of compounds capable of reversing antibiotic resistance in vivo.
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Affiliation(s)
- David D Boehr
- Antimicrobial Research Centre, Department of Biochemistry, McMaster University, Hamilton, Ontario L8N 3Z5, Canada
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Abstract
In this issue of Chemistry & Biology, Wright and colleagues report an elegant method for inhibiting enzymes critical for rendering bacteria drug resistant. By using cationic peptides as inhibitors, the authors have exploited two antibacterial mechanisms, making it doubly difficult for microbial retaliation.
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Affiliation(s)
- John S Blanchard
- Department of Biochemistry, Albert Einstein College of Medicine of Yeshiva University, Jack and Pearl Resnick Campus, 1300 Morris Park Avenue, Bronx, NY 10461, USA
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Boehr DD, Draker KA, Koteva K, Bains M, Hancock RE, Wright GD. Broad-spectrum peptide inhibitors of aminoglycoside antibiotic resistance enzymes. CHEMISTRY & BIOLOGY 2003; 10:189-96. [PMID: 12618191 DOI: 10.1016/s1074-5521(03)00026-7] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The action of aminoglycoside antibiotics is inhibited by chemical modification catalyzed by aminoglycoside inactivating enzymes, which bind these cationic saccharides with active site pockets that contain a preponderance of negatively charged residues. In this study, it was observed that several cationic antimicrobial peptides, representing different structural classes, could serve as inhibitors of such aminoglycoside resistance enzymes. The bovine antimicrobial peptide indolicidin and synthetic analogs appeared to be especially effective against a range of resistance enzymes, inhibiting enzymes belonging to both aminoglycoside phosphotransferase and aminoglycoside acetyltransferase classes, where the mode of action was dependent on the class of antibiotic resistance enzyme. These peptides represent the first example of broad-spectrum inhibitors of aminoglycoside resistance enzymes.
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Affiliation(s)
- David D Boehr
- Antimicrobial Research Centre, Department of Biochemistry, McMaster University, 1200 Main Street West, Hamilton, Ontario L8N 3Z5, Canada
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Boehr DD, Farley AR, Wright GD, Cox JR. Analysis of the pi-pi stacking interactions between the aminoglycoside antibiotic kinase APH(3')-IIIa and its nucleotide ligands. CHEMISTRY & BIOLOGY 2002; 9:1209-17. [PMID: 12445771 DOI: 10.1016/s1074-5521(02)00245-4] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
A key contact in the active site of an aminoglycoside phosphotransferase enzyme (APH(3')-IIIa) is a pi-pi stacking interaction between Tyr42 and the adenine ring of bound nucleotides. We investigated the prevalence of similar Tyr-adenine contacts and found that many different protein systems employ Tyr residues in the recognition of the adenine ring. The geometry of these stacking interactions suggests that electrostatics play a role in the attraction between these aromatic systems. Kinetic and calorimetric experiments on wild-type and mutant forms of APH(3')-IIIa yielded further experimental evidence of the importance of electrostatics in the adenine binding region and suggested that the stacking interaction contributes approximately 2 kcal/mol of binding energy. This type of information concerning the forces that govern nucleotide binding in APH(3')-IIIa will facilitate inhibitor design strategies that target the nucleotide binding site of APH-type enzymes.
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Affiliation(s)
- David D Boehr
- Antimicrobial Research Centre, Department of Biochemistry, McMaster University, 1200 Main Street West, Hamilton, Ontario L8N 3Z5, Canada
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Lee HK, Vakulenko SB, Clewell DB, Lerner SA, Chow JW. Mutations in the aph(2")-Ic gene are responsible for increased levels of aminoglycoside resistance. Antimicrob Agents Chemother 2002; 46:3253-6. [PMID: 12234853 PMCID: PMC128768 DOI: 10.1128/aac.46.10.3253-3256.2002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Random PCR mutagenesis of the enterococcal aph(2")-Ic gene followed by selection for mutant enzymes that confer enhanced levels of aminoglycoside resistance resulted in mutants of APH(2")-Ic with His-258-Leu and Phe-108-Leu substitutions, all of which conferred rises in the MICs of several aminoglycosides. The mutated residues are located outside conserved regions of aminoglycoside phosphotransferases.
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Affiliation(s)
- Hae Kyung Lee
- Division of Infectious Diseases, Wayne State University, Detroit, Michigan 48201, USA
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