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Alawam AS, M Alneghery L, Alwethaynani MS, Alamri MA. A hierarchical approach towards identification of novel inhibitors against L, D-transpeptidase YcbB as an anti-bacterial therapeutic target. J Biomol Struct Dyn 2024:1-11. [PMID: 38411016 DOI: 10.1080/07391102.2024.2322619] [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: 10/22/2023] [Accepted: 02/16/2024] [Indexed: 02/28/2024]
Abstract
The bacterial cell wall, being a vital component for cell viability, is regarded as a promising drug target. The L, D-Transpeptidase YcbB enzyme has been implicated for a significant role in cell wall polymers cross linking during typhoid toxin release, β-lactam resistance and outer membrane defect rescue. These observations have been recorded in different bacterial pathogens such as Salmonella Typhimurium, Citrobacter rodentium, and Salmonella typhi. In this work, we have shown structure based virtual screening of diverse natural and synthetic drug libraries against the enzyme and revealed three compounds as LAS_32135590, LAS_34036730 and LAS-51380924. These compounds showed highly stable energies and the findings are very competitive with the control molecule ((1RG or (4 R,5S)-3-({(3S,5S)-5-[(3-carboxyphenyl)carbamoyl]pyrrolidin-3-yl}sulfanyl)-5-[(1S,2R)-1-formyl-2-hydroxypropyl]-4-methyl-4,5-dihydro-1H-pyrrole-2-carboxylic acid or ertapenem)) used. Compared to control (which has binding energy score of -11.63 kcal/mol), the compounds showed better binding energy. The binding energy score of LAS_32135590, LAS_34036730 and LAS-51380924 is -12.63 kcal/mol, -12.22 kcal/mol and -12.10 kcal/mol, respectively. Further, the docked snapshot of the lead compounds and control were investigated for stability under time dependent dynamics environment. All the three leads complex and control system showed significant equilibrium (mean RMSD < 3 Å) both in term of intermolecular docked conformation and binding interactions network. Further validation on the complex's stability was acquired from the end-state MMPB/GBSA analysis that observed greater contribution from van der Waals forces and electrostatic energy while less contribution was noticed from solvation part. The compounds were also showed good drug-likeness and are non-toxic and non-mutagenic. In short, the compounds can be used in experimental testing's and might be subjected to structure modification to get better results.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Abdullah S Alawam
- Department of Biology, College of Science, Imam Mohammad Ibn Saud Islamic University (IMSIU), Riyadh, Saudi Arabia
| | - Lina M Alneghery
- Department of Biology, College of Science, Imam Mohammad Ibn Saud Islamic University (IMSIU), Riyadh, Saudi Arabia
| | - Maher S Alwethaynani
- Department of Clinical Laboratory Sciences, College of Applied Medical Sciences, Shaqra University, Al-Quwayiyah, Saudi Arabia
| | - Mubarak A Alamri
- Department of Pharmaceutical Chemistry, College of Pharmacy, Prince Sattam Bin Abdulaziz University, Al-Kharj, Saudi Arabia
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Galley NF, Greetham D, Alamán-Zárate MG, Williamson MP, Evans CA, Spittal WD, Buddle JE, Freeman J, Davis GL, Dickman MJ, Wilcox MH, Lovering AL, Fagan RP, Mesnage S. Clostridioides difficile canonical L,D-transpeptidases catalyze a novel type of peptidoglycan cross-links and are not required for beta-lactam resistance. J Biol Chem 2024; 300:105529. [PMID: 38043796 PMCID: PMC10792238 DOI: 10.1016/j.jbc.2023.105529] [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: 10/13/2023] [Revised: 11/19/2023] [Accepted: 11/27/2023] [Indexed: 12/05/2023] Open
Abstract
Clostridioides difficile is the leading cause of antibiotic-associated diarrhea worldwide with significant morbidity and mortality. This organism is naturally resistant to several beta-lactam antibiotics that inhibit the polymerization of peptidoglycan, an essential component of the bacteria cell envelope. Previous work has revealed that C. difficile peptidoglycan has an unusual composition. It mostly contains 3-3 cross-links, catalyzed by enzymes called L,D-transpeptidases (Ldts) that are poorly inhibited by beta-lactams. It was therefore hypothesized that peptidoglycan polymerization by these enzymes could underpin antibiotic resistance. Here, we investigated the catalytic activity of the three canonical Ldts encoded by C. difficile (LdtCd1, LdtCd2, and LdtCd3) in vitro and explored their contribution to growth and antibiotic resistance. We show that two of these enzymes catalyze the formation of novel types of peptidoglycan cross-links using meso-diaminopimelic acid both as a donor and an acceptor, also observed in peptidoglycan sacculi. We demonstrate that the simultaneous deletion of these three genes only has a minor impact on both peptidoglycan structure and resistance to beta-lactams. This unexpected result therefore implies that the formation of 3-3 peptidoglycan cross-links in C. difficile is catalyzed by as yet unidentified noncanonical Ldt enzymes.
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Affiliation(s)
- Nicola F Galley
- School of Biosciences, University of Sheffield, Sheffield, UK
| | - Darren Greetham
- School of Biosciences, University of Sheffield, Sheffield, UK
| | | | | | - Caroline A Evans
- Department of Chemical and Biological Engineering, University of Sheffield, Sheffield, UK
| | - William D Spittal
- Department of Microbiology, Leeds Teaching Hospitals NHS Trust, Leeds Institute of Medical Research, University of Leeds, Leeds, UK; Healthcare Associated Infections Research Group, Leeds Institute of Medical Research University of Leeds, Leeds, UK
| | | | - Jane Freeman
- Department of Microbiology, Leeds Teaching Hospitals NHS Trust, Leeds Institute of Medical Research, University of Leeds, Leeds, UK; Healthcare Associated Infections Research Group, Leeds Institute of Medical Research University of Leeds, Leeds, UK
| | - Georgina L Davis
- Department of Microbiology, Leeds Teaching Hospitals NHS Trust, Leeds Institute of Medical Research, University of Leeds, Leeds, UK; Healthcare Associated Infections Research Group, Leeds Institute of Medical Research University of Leeds, Leeds, UK
| | - Mark J Dickman
- Department of Chemical and Biological Engineering, University of Sheffield, Sheffield, UK
| | - Mark H Wilcox
- Department of Microbiology, Leeds Teaching Hospitals NHS Trust, Leeds Institute of Medical Research, University of Leeds, Leeds, UK; Healthcare Associated Infections Research Group, Leeds Institute of Medical Research University of Leeds, Leeds, UK
| | | | - Robert P Fagan
- School of Biosciences, University of Sheffield, Sheffield, UK
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Bailey J, Gallagher L, Manoil C. Genome-scale analysis of essential gene knockout mutants to identify an antibiotic target process. Antimicrob Agents Chemother 2023; 67:e0110223. [PMID: 37966228 PMCID: PMC10720506 DOI: 10.1128/aac.01102-23] [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: 08/29/2023] [Accepted: 09/22/2023] [Indexed: 11/16/2023] Open
Abstract
We describe a genome-scale approach to identify the essential biological process targeted by a new antibiotic. The procedure is based on the identification of essential genes whose inactivation sensitizes a Gram-negative bacterium (Acinetobacter baylyi) to a drug and employs recently developed transposon mutant screening and single-mutant validation procedures. The approach, based on measuring the rates of loss of newly generated knockout mutants in the presence of antibiotic, provides an alternative to traditional procedures for studying essential functions using conditional expression or activity alleles. As a proof of principle study, we evaluated whether mutations enhancing sensitivity to the β-lactam antibiotic meropenem corresponded to the known essential target process of the antibiotic (septal peptidoglycan synthesis). We found that indeed mutations inactivating most genes needed for peptidoglycan synthesis and cell division strongly sensitized cells to meropenem. Additional classes of sensitizing mutations in essential genes were also identified, including those that inactivated capsule synthesis, DNA replication, or envelope stress response regulation. The essential capsule synthesis mutants appeared to enhance meropenem sensitivity by depleting a precursor needed for both capsule and peptidoglycan synthesis. The replication mutants may sensitize cells by impairing division. Nonessential gene mutations sensitizing cells to meropenem were also identified in the screen and largely corresponded to functions subordinately associated with the essential target process, such as in peptidoglycan recycling. Overall, these results help validate a new approach to identify the essential process targeted by an antibiotic and define the larger functional network determining sensitivity to it.
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Affiliation(s)
- J. Bailey
- Department of Genome Sciences, University of Washington, Seattle, Washington, USA
| | - L. Gallagher
- Department of Genome Sciences, University of Washington, Seattle, Washington, USA
| | - C. Manoil
- Department of Genome Sciences, University of Washington, Seattle, Washington, USA
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Colquhoun JM, Farokhyfar M, Anderson AC, Bethel CR, Bonomo RA, Clarke AJ, Rather PN. Collateral Changes in Cell Physiology Associated with ADC-7 β-Lactamase Expression in Acinetobacter baumannii. Microbiol Spectr 2023; 11:e0464622. [PMID: 37074187 PMCID: PMC10269689 DOI: 10.1128/spectrum.04646-22] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Accepted: 03/15/2023] [Indexed: 04/20/2023] Open
Abstract
The ADC (AmpC) β-lactamase is universally present in the Acinetobacter baumannii chromosome, suggesting it may have a yet-to-be-identified cellular function. Using peptidoglycan composition analysis, we show that overexpressing the ADC-7 β-lactamase in A. baumannii drives changes consistent with altered l,d-transpeptidase activity. Based on this, we tested whether cells overexpressing ADC-7 would exhibit new vulnerabilities. As proof of principle, a screen of transposon insertions revealed that an insertion in the distal 3' end of canB, encoding carbonic anhydrase, resulted in a significant loss of viability when the adc-7 gene was overexpressed. A canB deletion mutant exhibited a more pronounced loss of viability than the transposon insertion, and this became amplified when cells overexpressed ADC-7. Interestingly, overexpression of the OXA-23 or TEM-1 β-lactamases also led to a pronounced loss of viability in cells with reduced carbonic anhydrase activity. In addition, we demonstrate that reduced CanB activity led to increased sensitivity to peptidoglycan synthesis inhibitors and to the carbonic anhydrase inhibitor ethoxzolamide. Furthermore, this strain exhibited a synergistic interaction with the peptidoglycan inhibitor fosfomycin and ethoxzolamide. Our results highlight the impact of ADC-7 overexpression on cell physiology and reveal that the essential carbonic anhydrase CanB may represent a novel target for antimicrobial agents that would exhibit increased potency against β-lactamase-overexpressing A. baumannii. IMPORTANCE Acinetobacter baumannii has become resistant to all classes of antibiotics, with β-lactam resistance responsible for the majority of treatment failures. New classes of antimicrobials are needed to treat this high-priority pathogen. This study had uncovered a new genetic vulnerability in β-lactamase-expressing A. baumannii, where reduced carbonic anhydrase activity becomes lethal. Inhibitors of carbonic anhydrase could represent a new method for treating A. baumannii infections.
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Affiliation(s)
- Jennifer M. Colquhoun
- Department of Microbiology and Immunology, Emory University, Atlanta, Georgia, USA
- Emory Antibiotic Resistance Center, Emory University, Atlanta, Georgia, USA
| | | | - Alexander C. Anderson
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
| | - Christopher R. Bethel
- Research Service, Louis Stokes Cleveland Department of Veterans Affairs, Cleveland, Ohio, USA
| | - Robert A. Bonomo
- Research Service, Louis Stokes Cleveland Department of Veterans Affairs, Cleveland, Ohio, USA
- Department of Biochemistry, Case Western Reserve University, Cleveland, Ohio, USA
- Department of Medicine, Case Western Reserve University, Cleveland, Ohio, USA
- Department of Molecular Biology and Microbiology, Case Western Reserve University, Cleveland, Ohio, USA
- Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio, USA
- Department of Proteomics and Bioinformatics, Case Western Reserve University, Cleveland, Ohio, USA
- CWRU-Cleveland VAMC Center for Antimicrobial Resistance and Epidemiology (Case VA CARES), Case Western Reserve University, Cleveland, Ohio, USA
| | - Anthony J. Clarke
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
- Department of Chemistry & Biochemistry, Wilfrid Laurier University, Waterloo, Ontario, Canada
| | - Philip N. Rather
- Department of Microbiology and Immunology, Emory University, Atlanta, Georgia, USA
- Emory Antibiotic Resistance Center, Emory University, Atlanta, Georgia, USA
- Research Service, Atlanta VA Medical Center, Decatur, Georgia, USA
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