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de Munnik M, Lang PA, Calvopiña K, Rabe P, Brem J, Schofield CJ. Biochemical and crystallographic studies of L,D-transpeptidase 2 from Mycobacterium tuberculosis with its natural monomer substrate. Commun Biol 2024; 7:1173. [PMID: 39294212 PMCID: PMC11410929 DOI: 10.1038/s42003-024-06785-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2024] [Accepted: 08/27/2024] [Indexed: 09/20/2024] Open
Abstract
The essential L,D-transpeptidase of Mycobacterium tuberculosis (LdtMt2) catalyses the formation of 3 → 3 cross-links in cell wall peptidoglycan and is a target for development of antituberculosis therapeutics. Efforts to inhibit LdtMt2 have been hampered by lack of knowledge of how it binds its substrate. To address this gap, we optimised the isolation of natural disaccharide tetrapeptide monomers from the Corynebacterium jeikeium bacterial cell wall through overproduction of the peptidoglycan sacculus. The tetrapeptides were used in binding / turnover assays and biophysical studies on LdtMt2. We determined a crystal structure of wild-type LdtMt2 reacted with its natural substrate, the tetrapeptide monomer of the peptidoglycan layer. This structure shows formation of a thioester linking the catalytic cysteine and the donor substrate, reflecting an intermediate in the transpeptidase reaction; it informs on the mode of entrance of the donor substrate into the LdtMt2 active site. The results will be useful in design of LdtMt2 inhibitors, including those based on substrate binding interactions, a strategy successfully employed for other nucleophilic cysteine enzymes.
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Affiliation(s)
- Mariska de Munnik
- Chemistry Research Laboratory, Department of Chemistry and the Ineos Oxford Institute of Antimicrobial Research, University of Oxford, Oxford, UK
| | - Pauline A Lang
- Chemistry Research Laboratory, Department of Chemistry and the Ineos Oxford Institute of Antimicrobial Research, University of Oxford, Oxford, UK
| | - Karina Calvopiña
- Chemistry Research Laboratory, Department of Chemistry and the Ineos Oxford Institute of Antimicrobial Research, University of Oxford, Oxford, UK
| | - Patrick Rabe
- Chemistry Research Laboratory, Department of Chemistry and the Ineos Oxford Institute of Antimicrobial Research, University of Oxford, Oxford, UK
| | - Jürgen Brem
- Chemistry Research Laboratory, Department of Chemistry and the Ineos Oxford Institute of Antimicrobial Research, University of Oxford, Oxford, UK
- Enzymology and Applied Biocatalysis Research Center, Faculty of Chemistry and Chemical Engineering, Babes-Bolyai University, Cluj-Napoca, Romania
| | - Christopher J Schofield
- Chemistry Research Laboratory, Department of Chemistry and the Ineos Oxford Institute of Antimicrobial Research, University of Oxford, Oxford, UK.
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2
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Bollinger KW, Müh U, Ocius KL, Apostolos AJ, Pires MM, Helm RF, Popham DL, Weiss DS, Ellermeier CD. Identification of a family of peptidoglycan transpeptidases reveals that Clostridioides difficile requires noncanonical cross-links for viability. Proc Natl Acad Sci U S A 2024; 121:e2408540121. [PMID: 39150786 PMCID: PMC11348318 DOI: 10.1073/pnas.2408540121] [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: 04/30/2024] [Accepted: 07/12/2024] [Indexed: 08/18/2024] Open
Abstract
Most bacteria are surrounded by a cell wall that contains peptidoglycan (PG), a large polymer composed of glycan strands held together by short peptide cross-links. There are two major types of cross-links, termed 4-3 and 3-3 based on the amino acids involved. 4-3 cross-links are created by penicillin-binding proteins, while 3-3 cross-links are created by L,D-transpeptidases (LDTs). In most bacteria, the predominant mode of cross-linking is 4-3, and these cross-links are essential for viability, while 3-3 cross-links comprise only a minor fraction and are not essential. However, in the opportunistic intestinal pathogen Clostridioides difficile, about 70% of the cross-links are 3-3. We show here that 3-3 cross-links and LDTs are essential for viability in C. difficile. We also show that C. difficile has five LDTs, three with a YkuD catalytic domain as in all previously known LDTs and two with a VanW catalytic domain, whose function was until now unknown. The five LDTs exhibit extensive functional redundancy. VanW domain proteins are found in many gram-positive bacteria but scarce in other lineages. We tested seven non-C. difficile VanW domain proteins and confirmed LDT activity in three cases. In summary, our findings uncover a previously unrecognized family of PG cross-linking enzymes, assign a catalytic function to VanW domains, and demonstrate that 3-3 cross-linking is essential for viability in C. difficile, the first time this has been shown in any bacterial species. The essentiality of LDTs in C. difficile makes them potential targets for antibiotics that kill C. difficile selectively.
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Affiliation(s)
- Kevin W. Bollinger
- Department of Microbiology and Immunology, Carver College of Medicine, University of Iowa, Iowa City, IA52242
| | - Ute Müh
- Department of Microbiology and Immunology, Carver College of Medicine, University of Iowa, Iowa City, IA52242
| | - Karl L. Ocius
- Department of Chemistry, University of Virginia, Charlottesville, VA22904
| | | | - Marcos M. Pires
- Department of Chemistry, University of Virginia, Charlottesville, VA22904
| | - Richard F. Helm
- Department of Biochemistry, Virginia Tech, Blacksburg, VA24061
| | - David L. Popham
- Department of Biological Sciences, Virginia Tech, Blacksburg, VA24061
| | - David S. Weiss
- Department of Microbiology and Immunology, Carver College of Medicine, University of Iowa, Iowa City, IA52242
- Graduate Program in Genetics, University of Iowa, Iowa City, IA52242
| | - Craig D. Ellermeier
- Department of Microbiology and Immunology, Carver College of Medicine, University of Iowa, Iowa City, IA52242
- Graduate Program in Genetics, University of Iowa, Iowa City, IA52242
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3
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Bollinger KW, Müh U, Ocius KL, Apostolos AJ, Pires MM, Helm RF, Popham DL, Weiss DS, Ellermeier CD. Identification of a new family of peptidoglycan transpeptidases reveals atypical crosslinking is essential for viability in Clostridioides difficile. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.14.584917. [PMID: 38559057 PMCID: PMC10980060 DOI: 10.1101/2024.03.14.584917] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
Clostridioides difficile, the leading cause of antibiotic-associated diarrhea, relies primarily on 3-3 crosslinks created by L,D-transpeptidases (LDTs) to fortify its peptidoglycan (PG) cell wall. This is unusual, as in most bacteria the vast majority of PG crosslinks are 4-3 crosslinks, which are created by penicillin-binding proteins (PBPs). Here we report the unprecedented observation that 3-3 crosslinking is essential for viability in C. difficile. We also report the discovery of a new family of LDTs that use a VanW domain to catalyze 3-3 crosslinking rather than a YkuD domain as in all previously known LDTs. Bioinformatic analyses indicate VanW domain LDTs are less common than YkuD domain LDTs and are largely restricted to Gram-positive bacteria. Our findings suggest that LDTs might be exploited as targets for antibiotics that kill C. difficile without disrupting the intestinal microbiota that is important for keeping C. difficile in check.
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Affiliation(s)
- Kevin W. Bollinger
- Department of Microbiology and Immunology, Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - Ute Müh
- Department of Microbiology and Immunology, Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - Karl L. Ocius
- Department of Chemistry, University of Virginia, Charlottesville, VA, USA
| | - Alexis J. Apostolos
- Department of Chemistry, University of Virginia, Charlottesville, VA, USA
- Present address: Haleon, 1211 Sherwood Ave, Richmond, VA 23220
| | - Marcos M. Pires
- Department of Chemistry, University of Virginia, Charlottesville, VA, USA
| | - Richard F. Helm
- Department of Biochemistry, Virginia Tech, Blacksburg, VA, USA
| | - David L. Popham
- Department of Biological Sciences, Virginia Tech, Blacksburg, VA, USA
| | - David S. Weiss
- Department of Microbiology and Immunology, Carver College of Medicine, University of Iowa, Iowa City, IA, USA
- Graduate Program in Genetics, University of Iowa, Iowa City, IA USA
| | - Craig D. Ellermeier
- Department of Microbiology and Immunology, Carver College of Medicine, University of Iowa, Iowa City, IA, USA
- Graduate Program in Genetics, University of Iowa, Iowa City, IA USA
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4
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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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5
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Espaillat A, Alvarez L, Torrens G, Ter Beek J, Miguel-Ruano V, Irazoki O, Gago F, Hermoso JA, Berntsson RPA, Cava F. A distinctive family of L,D-transpeptidases catalyzing L-Ala-mDAP crosslinks in Alpha- and Betaproteobacteria. Nat Commun 2024; 15:1343. [PMID: 38351082 PMCID: PMC10864386 DOI: 10.1038/s41467-024-45620-5] [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: 11/09/2023] [Accepted: 01/29/2024] [Indexed: 02/16/2024] Open
Abstract
The bacterial cell-wall peptidoglycan is made of glycan strands crosslinked by short peptide stems. Crosslinks are catalyzed by DD-transpeptidases (4,3-crosslinks) and LD-transpeptidases (3,3-crosslinks). However, recent research on non-model species has revealed novel crosslink types, suggesting the existence of uncharacterized enzymes. Here, we identify an LD-transpeptidase, LDTGo, that generates 1,3-crosslinks in the acetic-acid bacterium Gluconobacter oxydans. LDTGo-like proteins are found in Alpha- and Betaproteobacteria lacking LD3,3-transpeptidases. In contrast with the strict specificity of typical LD- and DD-transpeptidases, LDTGo can use non-terminal amino acid moieties for crosslinking. A high-resolution crystal structure of LDTGo reveals unique features when compared to LD3,3-transpeptidases, including a proline-rich region that appears to limit substrate access, and a cavity accommodating both glycan chain and peptide stem from donor muropeptides. Finally, we show that DD-crosslink turnover is involved in supplying the necessary substrate for LD1,3-transpeptidation. This phenomenon underscores the interplay between distinct crosslinking mechanisms in maintaining cell wall integrity in G. oxydans.
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Affiliation(s)
- Akbar Espaillat
- Department of Molecular Biology and Laboratory for Molecular Infection Medicine Sweden, Umeå Centre for Microbial Research, SciLifeLab, Umeå University, Umeå, Sweden
- Chr. Hansen A/S, Microbial Physiology, R&D, 2970, Hoersholm, Denmark
| | - Laura Alvarez
- Department of Molecular Biology and Laboratory for Molecular Infection Medicine Sweden, Umeå Centre for Microbial Research, SciLifeLab, Umeå University, Umeå, Sweden
| | - Gabriel Torrens
- Department of Molecular Biology and Laboratory for Molecular Infection Medicine Sweden, Umeå Centre for Microbial Research, SciLifeLab, Umeå University, Umeå, Sweden
| | - Josy Ter Beek
- Department of Medical Biochemistry and Biophysics, Umeå University, Umeå, Sweden
- Wallenberg Centre for Molecular Medicine, Umeå University, Umeå, Sweden
| | - Vega Miguel-Ruano
- Department of Crystallography and Structural Biology, Institute of Physical Chemistry "Blas Cabrera", CSIC, Madrid, Spain
| | - Oihane Irazoki
- Department of Molecular Biology and Laboratory for Molecular Infection Medicine Sweden, Umeå Centre for Microbial Research, SciLifeLab, Umeå University, Umeå, Sweden
| | - Federico Gago
- Department of Biomedical Sciences & IQM-CSIC Associate Unit, School of Medicine and Health Sciences, University of Alcalá, E-28805, Madrid, Alcalá de Henares, Spain
| | - Juan A Hermoso
- Department of Crystallography and Structural Biology, Institute of Physical Chemistry "Blas Cabrera", CSIC, Madrid, Spain
| | - Ronnie P-A Berntsson
- Department of Medical Biochemistry and Biophysics, Umeå University, Umeå, Sweden
- Wallenberg Centre for Molecular Medicine, Umeå University, Umeå, Sweden
| | - Felipe Cava
- Department of Molecular Biology and Laboratory for Molecular Infection Medicine Sweden, Umeå Centre for Microbial Research, SciLifeLab, Umeå University, Umeå, Sweden.
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6
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Theuretzbacher U, Blasco B, Duffey M, Piddock LJV. Unrealized targets in the discovery of antibiotics for Gram-negative bacterial infections. Nat Rev Drug Discov 2023; 22:957-975. [PMID: 37833553 DOI: 10.1038/s41573-023-00791-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/15/2023] [Indexed: 10/15/2023]
Abstract
Advances in areas that include genomics, systems biology, protein structure determination and artificial intelligence provide new opportunities for target-based antibacterial drug discovery. The selection of a 'good' new target for direct-acting antibacterial compounds is the first decision, for which multiple criteria must be explored, integrated and re-evaluated as drug discovery programmes progress. Criteria include essentiality of the target for bacterial survival, its conservation across different strains of the same species, bacterial species and growth conditions (which determines the spectrum of activity of a potential antibiotic) and the level of homology with human genes (which influences the potential for selective inhibition). Additionally, a bacterial target should have the potential to bind to drug-like molecules, and its subcellular location will govern the need for inhibitors to penetrate one or two bacterial membranes, which is a key challenge in targeting Gram-negative bacteria. The risk of the emergence of target-based drug resistance for drugs with single targets also requires consideration. This Review describes promising but as-yet-unrealized targets for antibacterial drugs against Gram-negative bacteria and examples of cognate inhibitors, and highlights lessons learned from past drug discovery programmes.
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Affiliation(s)
| | - Benjamin Blasco
- Global Antibiotic Research and Development Partnership (GARDP), Geneva, Switzerland
| | - Maëlle Duffey
- Global Antibiotic Research and Development Partnership (GARDP), Geneva, Switzerland
| | - Laura J V Piddock
- Global Antibiotic Research and Development Partnership (GARDP), Geneva, Switzerland.
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7
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Xiao G, Li J, Sun Z. The Combination of Antibiotic and Non-Antibiotic Compounds Improves Antibiotic Efficacy against Multidrug-Resistant Bacteria. Int J Mol Sci 2023; 24:15493. [PMID: 37895172 PMCID: PMC10607837 DOI: 10.3390/ijms242015493] [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: 09/13/2023] [Revised: 10/19/2023] [Accepted: 10/21/2023] [Indexed: 10/29/2023] Open
Abstract
Bacterial antibiotic resistance, especially the emergence of multidrug-resistant (MDR) strains, urgently requires the development of effective treatment strategies. It is always of interest to delve into the mechanisms of resistance to current antibiotics and target them to promote the efficacy of existing antibiotics. In recent years, non-antibiotic compounds have played an important auxiliary role in improving the efficacy of antibiotics and promoting the treatment of drug-resistant bacteria. The combination of non-antibiotic compounds with antibiotics is considered a promising strategy against MDR bacteria. In this review, we first briefly summarize the main resistance mechanisms of current antibiotics. In addition, we propose several strategies to enhance antibiotic action based on resistance mechanisms. Then, the research progress of non-antibiotic compounds that can promote antibiotic-resistant bacteria through different mechanisms in recent years is also summarized. Finally, the development prospects and challenges of these non-antibiotic compounds in combination with antibiotics are discussed.
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Affiliation(s)
| | | | - Zhiliang Sun
- College of Veterinary Medicine, Hunan Agricultural University, Changsha 410128, China; (G.X.); (J.L.)
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8
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Marques PH, Jaiswal AK, de Almeida FA, Pinto UM, Ferreira-Machado AB, Tiwari S, Soares SDC, Paiva AD. Lactic acid bacteria secreted proteins as potential Listeria monocytogenes quorum sensing inhibitors. Mol Divers 2023:10.1007/s11030-023-10722-7. [PMID: 37658910 DOI: 10.1007/s11030-023-10722-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Accepted: 08/20/2023] [Indexed: 09/05/2023]
Abstract
Listeria monocytogenes is an important human and animal pathogen able to cause an infection named listeriosis and is mainly transmitted through contaminated food. Among its virulence traits, the ability to form biofilms and to survive in harsh environments stand out and lead to the persistence of L. monocytogenes for long periods in food processing environments. Virulence and biofilm formation are phenotypes regulated by quorum sensing (QS) and, therefore, the control of L. monocytogenes through an anti-QS strategy is promising. This study aimed to identify, by in silico approaches, proteins secreted by lactic acid bacteria (LAB) potentially able to interfere with the agr QS system of L. monocytogenes. The genome mining of Lacticaseibacillus rhamnosus GG and Lactobacillus acidophilus NCFM revealed 151 predicted secreted proteins. Concomitantly, the three-dimensional (3D) structures of AgrB and AgrC proteins of L. monocytogenes were modeled and validated, and their active sites were predicted. Through protein-protein docking and molecular dynamic, Serine-type D-Ala-D-Ala carboxypeptidase and L,D-transpeptidase, potentially secreted by L. rhamnosus GG and L. acidophilus NCFM, respectively, were identified with high affinity to AgrB and AgrC proteins, respectively. By inhibiting the translocation of the cyclic autoinducer peptide (cyclic AIP) via AgrB, and its recognition in the active site of AgrC, these LAB proteins could disrupt L. monocytogenes communication by impairing the agr QS system. The application of the QS inhibitors predicted in this study can emerge as a promising strategy in controlling L. monocytogenes in food processing environment and as an adjunct to antibiotic therapy for the treatment of listeriosis.
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Affiliation(s)
- Pedro Henrique Marques
- Interunit Bioinformatics Graduate Program, Federal University of Minas Gerais (UFMG), Belo Horizonte, Minas Gerais, Brazil
| | - Arun Kumar Jaiswal
- Interunit Bioinformatics Graduate Program, Federal University of Minas Gerais (UFMG), Belo Horizonte, Minas Gerais, Brazil
| | - Felipe Alves de Almeida
- Instituto de Laticínios Cândido Tostes (ILCT), Empresa de Pesquisa Agropecuária de Minas Gerais (EPAMIG), Juiz de Fora, Minas Gerais, Brazil
| | - Uelinton Manoel Pinto
- Food Research Center, Department of Food and Experimental Nutrition, Faculty of Pharmaceutical Sciences, University of São Paulo (USP), São Paulo, Brazil
| | | | - Sandeep Tiwari
- Institute of Biology, Federal University of Bahia (UFBA), Salvador, Bahia, Brazil
- Institute of Health Sciences, Federal University of Bahia (UFBA), Salvador, Bahia, Brazil
| | - Siomar de Castro Soares
- Department of Microbiology, Immunology and Parasitology, Federal University of Triângulo Mineiro (UFTM), Uberaba, Minas Gerais, Brazil
| | - Aline Dias Paiva
- Department of Microbiology, Immunology and Parasitology, Federal University of Triângulo Mineiro (UFTM), Uberaba, Minas Gerais, Brazil.
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9
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Hugonneau-Beaufet I, Barnier JP, Thiriet-Rupert S, Létoffé S, Mainardi JL, Ghigo JM, Beloin C, Arthur M. Characterization of Pseudomonas aeruginosa l,d-Transpeptidases and Evaluation of Their Role in Peptidoglycan Adaptation to Biofilm Growth. Microbiol Spectr 2023; 11:e0521722. [PMID: 37255442 PMCID: PMC10434034 DOI: 10.1128/spectrum.05217-22] [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: 12/20/2022] [Accepted: 04/18/2023] [Indexed: 06/01/2023] Open
Abstract
Peptidoglycan is an essential component of the bacterial cell envelope that sustains the turgor pressure of the cytoplasm, determines cell shape, and acts as a scaffold for the anchoring of envelope polymers such as lipoproteins. The final cross-linking step of peptidoglycan polymerization is performed by classical d,d-transpeptidases belonging to the penicillin-binding protein (PBP) family and by l,d-transpeptidases (LDTs), which are dispensable for growth in most bacterial species and whose physiological functions remain elusive. In this study, we investigated the contribution of LDTs to cell envelope synthesis in Pseudomonas aeruginosa grown in planktonic and biofilm conditions. We first assigned a function to each of the three P. aeruginosa LDTs by gene inactivation in P. aeruginosa, heterospecific gene expression in Escherichia coli, and, for one of them, direct determination of its enzymatic activity. We found that the three P. aeruginosa LDTs catalyze peptidoglycan cross-linking (LdtPae1), the anchoring of lipoprotein OprI to the peptidoglycan (LdtPae2), and the hydrolysis of the resulting peptidoglycan-OprI amide bond (LdtPae3). Construction of a phylogram revealed that LDTs performing each of these three functions in various species cannot be assigned to distinct evolutionary lineages, in contrast to what has been observed with PBPs. We showed that biofilm, but not planktonic bacteria, displayed an increase proportion of peptidoglycan cross-links formed by LdtPae1 and a greater extent of OprI anchoring to peptidoglycan, which is controlled by LdtPae2 and LdtPae3. Consistently, deletion of each of the ldt genes impaired biofilm formation and potentiated the bactericidal activity of EDTA. These results indicate that LDTs contribute to the stabilization of the bacterial cell envelope and to the adaptation of peptidoglycan metabolism to growth in biofilm. IMPORTANCE Active-site cysteine LDTs form a functionally heterologous family of enzymes that contribute to the biogenesis of the bacterial cell envelope through formation of peptidoglycan cross-links and through the dynamic anchoring of lipoproteins to peptidoglycan. Here, we report the role of three P. aeruginosa LDTs that had not been previously characterized. We show that these enzymes contribute to resistance to the bactericidal activity of EDTA and to the adaptation of cell envelope polymers to conditions that prevail in biofilms. These results indicate that LDTs should be considered putative targets in the development of drug-EDTA associations for the control of biofilm-related infections.
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Affiliation(s)
- Inès Hugonneau-Beaufet
- Centre de Recherche des Cordeliers, Sorbonne Université, INSERM, Université Paris Cité, Paris, France
| | - Jean-Philippe Barnier
- Centre de Recherche des Cordeliers, Sorbonne Université, INSERM, Université Paris Cité, Paris, France
- Service de Microbiologie, Hôpital Européen Georges Pompidou, AP-HP Assistance Publique-Hôpitaux de Paris, Paris, France
- Université Paris Cité, Faculté de Santé, UFR de Médecine, Paris, France
| | - Stanislas Thiriet-Rupert
- Institut Pasteur, Université Paris Cité, UMR CNRS 6047, Genetics of Biofilms Laboratory, Paris, France
| | - Sylvie Létoffé
- Institut Pasteur, Université Paris Cité, UMR CNRS 6047, Genetics of Biofilms Laboratory, Paris, France
| | - Jean-Luc Mainardi
- Centre de Recherche des Cordeliers, Sorbonne Université, INSERM, Université Paris Cité, Paris, France
- Service de Microbiologie, Hôpital Européen Georges Pompidou, AP-HP Assistance Publique-Hôpitaux de Paris, Paris, France
- Université Paris Cité, Faculté de Santé, UFR de Médecine, Paris, France
| | - Jean-Marc Ghigo
- Institut Pasteur, Université Paris Cité, UMR CNRS 6047, Genetics of Biofilms Laboratory, Paris, France
| | - Christophe Beloin
- Institut Pasteur, Université Paris Cité, UMR CNRS 6047, Genetics of Biofilms Laboratory, Paris, France
| | - Michel Arthur
- Centre de Recherche des Cordeliers, Sorbonne Université, INSERM, Université Paris Cité, Paris, France
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10
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Darby EM, Trampari E, Siasat P, Gaya MS, Alav I, Webber MA, Blair JMA. Molecular mechanisms of antibiotic resistance revisited. Nat Rev Microbiol 2023; 21:280-295. [PMID: 36411397 DOI: 10.1038/s41579-022-00820-y] [Citation(s) in RCA: 263] [Impact Index Per Article: 263.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/17/2022] [Indexed: 11/22/2022]
Abstract
Antibiotic resistance is a global health emergency, with resistance detected to all antibiotics currently in clinical use and only a few novel drugs in the pipeline. Understanding the molecular mechanisms that bacteria use to resist the action of antimicrobials is critical to recognize global patterns of resistance and to improve the use of current drugs, as well as for the design of new drugs less susceptible to resistance development and novel strategies to combat resistance. In this Review, we explore recent advances in understanding how resistance genes contribute to the biology of the host, new structural details of relevant molecular events underpinning resistance, the identification of new resistance gene families and the interactions between different resistance mechanisms. Finally, we discuss how we can use this information to develop the next generation of antimicrobial therapies.
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Affiliation(s)
- Elizabeth M Darby
- College of Medical and Dental Sciences, Institute of Microbiology and Infection, University of Birmingham, Birmingham, UK
| | | | - Pauline Siasat
- College of Medical and Dental Sciences, Institute of Microbiology and Infection, University of Birmingham, Birmingham, UK
| | | | - Ilyas Alav
- College of Medical and Dental Sciences, Institute of Microbiology and Infection, University of Birmingham, Birmingham, UK
| | - Mark A Webber
- Quadram Institute Bioscience, Norwich Research Park, Norwich, UK.
- Medical School, University of East Anglia, Norwich Research Park, Norwich, UK.
| | - Jessica M A Blair
- College of Medical and Dental Sciences, Institute of Microbiology and Infection, University of Birmingham, Birmingham, UK.
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11
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Aurass P, Kim S, Pinedo V, Cava F, Isberg RR. Identification of Genes Required for Long-Term Survival of Legionella pneumophila in Water. mSphere 2023; 8:e0045422. [PMID: 36988466 PMCID: PMC10117105 DOI: 10.1128/msphere.00454-22] [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: 09/13/2022] [Accepted: 02/24/2023] [Indexed: 03/30/2023] Open
Abstract
Long-term survival of Legionella pneumophila in aquatic environments is thought to be important for facilitating epidemic outbreaks. Eliminating bacterial colonization in plumbing systems is the primary strategy that depletes this reservoir and prevents disease. To uncover L. pneumophila determinants facilitating survival in water, a Tn-seq strategy was used to identify survival-defective mutants during 50-day starvation in tap water at 42°C. The mutants with the most drastic survival defects carried insertions in electron transport chain genes, indicating that membrane energy charge and/or ATP synthesis requires the generation of a proton gradient by the respiratory chain to maintain survival in the presence of water stress. In addition, periplasmically localized proteins that are known (EnhC) or hypothesized (lpg1697) to stabilize the cell wall against turnover were essential for water survival. To test that the identified mutations disrupted water survival, candidate genes were knocked down by CRISPRi. The vast majority of knockdown strains with verified transcript depletion showed remarkably low viability after 50-day incubations. To demonstrate that maintenance of cell wall integrity was an important survival determinant, a deletion mutation in lpg1697, in a gene encoding a predicted l,d-transpeptidase domain, was analyzed. The loss of this gene resulted in increased osmolar sensitivity and carbenicillin hypersensitivity relative to the wild type, as predicted for loss of an l,d-transpeptidase. These results indicate that the L. pneumophila envelope has been evolutionarily selected to allow survival under conditions in which the bacteria are subjected to long-term exposure to starvation and low osmolar conditions. IMPORTANCE Water is the primary vector for transmission of L. pneumophila to humans, and the pathogen is adapted to persist in this environment for extended periods of time. Preventing survival of L. pneumophila in water is therefore critical for prevention of Legionnaires' disease. We analyzed dense transposon mutation pools for strains with severe survival defects during a 50-day water incubation at 42°C. By tracking the associated transposon insertion sites in the genome, we defined a distinct essential gene set for water survival and demonstrate that a predicted peptidoglycan cross-linking enzyme, lpg1697, and components of the electron transport chain are required to ensure survival of the pathogen. Our results indicate that select characteristics of the cell wall and components of the respiratory chain of L. pneumophila are primary evolutionary targets being shaped to promote its survival in water.
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Affiliation(s)
- Philipp Aurass
- Department of Enteropathogenic Bacteria and Legionella, Robert Koch Institute, Wernigerode, Germany
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts, USA
| | - Seongok Kim
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts, USA
| | - Victor Pinedo
- Laboratory for Molecular Infection Medicine Sweden, Department of Molecular Biology, Umeå Centre for Microbial Research, Umeå University, Umeå, Sweden
| | - Felipe Cava
- Laboratory for Molecular Infection Medicine Sweden, Department of Molecular Biology, Umeå Centre for Microbial Research, Umeå University, Umeå, Sweden
| | - Ralph R. Isberg
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts, USA
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12
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Toth M, Stewart NK, Smith CA, Lee M, Vakulenko SB. The l,d-Transpeptidase Ldt Ab from Acinetobacter baumannii Is Poorly Inhibited by Carbapenems and Has a Unique Structural Architecture. ACS Infect Dis 2022; 8:1948-1961. [PMID: 35973205 PMCID: PMC9764404 DOI: 10.1021/acsinfecdis.2c00321] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
l,d-Transpeptidases (LDTs) are enzymes that catalyze reactions essential for biogenesis of the bacterial cell wall, including formation of 3-3 cross-linked peptidoglycan. Unlike the historically well-known bacterial transpeptidases, the penicillin-binding proteins (PBPs), LDTs are resistant to inhibition by the majority of β-lactam antibiotics, with the exception of carbapenems and penems, allowing bacteria to survive in the presence of these drugs. Here we report characterization of LdtAb from the clinically important pathogen, Acinetobacter baumannii. We show that A. baumannii survives inactivation of LdtAb alone or in combination with PBP1b or PBP2, while simultaneous inactivation of LdtAb and PBP1a is lethal. Minimal inhibitory concentrations (MICs) of all 13 β-lactam antibiotics tested decreased 2- to 8-fold for the LdtAb deletion mutant, while further decreases were seen for both double mutants, with the largest, synergistic effect observed for the LdtAb + PBP2 deletion mutant. Mass spectrometry experiments showed that LdtAb forms complexes in vitro only with carbapenems. However, the acylation rate of these antibiotics is very slow, with the reaction taking longer than four hours to complete. Our X-ray crystallographic studies revealed that LdtAb has a unique structural architecture and is the only known LDT to have two different peptidoglycan-binding domains.
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Affiliation(s)
- Marta Toth
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Nichole K Stewart
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Clyde A Smith
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
- Stanford Synchrotron Radiation Lightsource, Menlo Park, California 94025, United States
| | - Mijoon Lee
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
- Mass Spectrometry and Proteomics Facility, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Sergei B Vakulenko
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
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13
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Lorente Cobo N, Sibinelli-Sousa S, Biboy J, Vollmer W, Bayer-Santos E, Prehna G. Molecular characterization of the type VI secretion system effector Tlde1a reveals a structurally altered LD-transpeptidase fold. J Biol Chem 2022; 298:102556. [PMID: 36183829 PMCID: PMC9638812 DOI: 10.1016/j.jbc.2022.102556] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Revised: 09/26/2022] [Accepted: 09/27/2022] [Indexed: 12/01/2022] Open
Abstract
The type VI secretion system (T6SS) is a molecular machine that Gram-negative bacteria have adapted for multiple functions, including interbacterial competition. Bacteria use the T6SS to deliver protein effectors into adjacent cells to kill rivals and establish niche dominance. Central to T6SS-mediated bacterial competition is an arms race to acquire diverse effectors to attack and neutralize target cells. The peptidoglycan has a central role in bacterial cell physiology, and effectors that biochemically modify peptidoglycan structure effectively induce cell death. One such T6SS effector is Tlde1a from Salmonella Typhimurium. Tlde1a functions as an LD-carboxypeptidase to cleave tetrapeptide stems and as an LD-transpeptidase to exchange the terminal D-alanine of a tetrapeptide stem with a noncanonical D-amino acid. To understand how Tlde1a exhibits toxicity at the molecular level, we determined the X-ray crystal structure of Tlde1a alone and in complex with D-amino acids. Our structural data revealed that Tlde1a possesses a unique LD-transpeptidase fold consisting of a dual pocket active site with a capping subdomain. This includes an exchange pocket to bind a D-amino acid for exchange and a catalytic pocket to position the D-alanine of a tetrapeptide stem for cleavage. Our toxicity assays in Escherichia coli and in vitro peptidoglycan biochemical assays with Tlde1a variants correlate Tlde1a molecular features directly to its biochemical functions. We observe that the LD-carboxypeptidase and LD-transpeptidase activities of Tlde1a are both structurally and functionally linked. Overall, our data highlight how an LD-transpeptidase fold has been structurally altered to create a toxic effector in the T6SS arms race.
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Affiliation(s)
- Neil Lorente Cobo
- Department of Microbiology, University of Manitoba, Winnipeg, Canada
| | - Stephanie Sibinelli-Sousa
- Department of Microbiology, Biomedical Sciences Institute, University of São Paulo, São Paulo, Brazil
| | - Jacob Biboy
- Centre for Bacterial Cell Biology, Biosciences Institute, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Waldemar Vollmer
- Centre for Bacterial Cell Biology, Biosciences Institute, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Ethel Bayer-Santos
- Department of Microbiology, Biomedical Sciences Institute, University of São Paulo, São Paulo, Brazil
| | - Gerd Prehna
- Department of Microbiology, University of Manitoba, Winnipeg, Canada.
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14
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Saqallah FG, Hamed WM, Talib WH, Dianita R, Wahab HA. Antimicrobial activity and molecular docking screening of bioactive components of Antirrhinum majus (snapdragon) aerial parts. Heliyon 2022; 8:e10391. [PMID: 36072262 PMCID: PMC9441312 DOI: 10.1016/j.heliyon.2022.e10391] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2021] [Revised: 05/19/2022] [Accepted: 08/15/2022] [Indexed: 11/28/2022] Open
Abstract
Background Antirrhinum majus (Snapdragon) is a perennial Mediterranean-native plant that is commonly used for mass display. Few reports acknowledged the traditional use of A. majus for its medicinal and therapeutic effects. Herein, we assess the impact of A. majus’s sample preparation and extraction methods on the plant-aerial parts’ phytochemical contents and antimicrobial activity. Furthermore, the microbial targets of the extracts’ secondary metabolites are inspected using molecular docking simulations. Methods The leaves and flowers of A. majus were prepared as fresh and air-dried samples, then extracted using cold maceration and hot reflux, respectively. Extracts with the best phytochemical profiles were selected to test their antimicrobial activities against Bacillus subtilis, Staphylococcus aureus, Enterobacter aerogenes, Escherichia coli and Candida albicans. Besides, molecular docking of 66 reported isolated compounds was conducted against various microbial targets. Results The dried-refluxed samples revealed a massive deterioration in their phytochemical profiles, whereas the macerated flowers extract exhibited the highest total phenolic content and antimicrobial activity against all tested bacterial strains. However, both flowers and leaves extracts showed similar minimum inhibitory and lethal concentrations against C. albicans. Molecular docking studies revealed that chlorogenic acid, chalcononaringenin 4’-glucoside, 3,4,2’,4’,6’-pentahydroxy-chalcone 4’-glucoside, apigenin-7-glucuronide, and luteolin-7-glucuronide were the lead compounds in expressing the antimicrobial activity. Yet, A. majus’s compounds could neither inhibit the 30S ribosomal subunit nor muramyl ligase E. Conclusion Our results suggest that cold maceration of A. majus fresh aerial parts gave higher flavonoid and phenolic content contributing to its antimicrobial properties. These flavonoids and phenolic compounds are predicted to have a crucial role in inhibiting fungal sterol 14-demethylase, and bacterial dihydropteroate synthase and gyrase B subunit proteins. Air-drying of A. majus’s aerial parts deteriorates its phytochemical composition, affecting its antimicrobial activity. A. majus’s fresh-flowers macerate exhibited the highest total phenolic content and antibacterial activity. The antimycotic activity of A. majus was the same for flowers and leaves macerates. In-silico results showed that some phenolics, chalcones, and flavonoids are responsible for the antimicrobial activity. A.majus’s components act on fungal sterol 14-demethylase, and bacterial dihydropteroate synthase and gyrase B enzymes.
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Affiliation(s)
- Fadi G. Saqallah
- Discipline of Pharmaceutical Chemistry, School of Pharmaceutical Sciences, Universiti Sains Malaysia, 11800 Minden, Penang, Malaysia
- Faculty of Pharmacy, Applied Science Private University, 11931, Amman, Jordan
| | - Wafaa M. Hamed
- Pharmacy Department, Al-Noor University College, 41019, Mosul, Iraq
- Corresponding author.
| | - Wamidh H. Talib
- Faculty of Pharmacy, Applied Science Private University, 11931, Amman, Jordan
| | - Roza Dianita
- Discipline of Pharmaceutical Chemistry, School of Pharmaceutical Sciences, Universiti Sains Malaysia, 11800 Minden, Penang, Malaysia
| | - Habibah A. Wahab
- Discipline of Pharmaceutical Technology, School of Pharmaceutical Sciences, Universiti Sains Malaysia, 11800 Minden, Penang, Malaysia
- Corresponding author.
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15
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Salleh MZ, Banga Singh KK, Deris ZZ. Structural Insights into Substrate Binding and Antibiotic Inhibition of Enterobacterial Penicillin-Binding Protein 6. LIFE (BASEL, SWITZERLAND) 2022; 12:life12071022. [PMID: 35888109 PMCID: PMC9320039 DOI: 10.3390/life12071022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Revised: 07/03/2022] [Accepted: 07/07/2022] [Indexed: 11/16/2022]
Abstract
Shigella sonnei remains the second most common cause of shigellosis in young children and is now increasingly dominant across developing countries. The global emergence of drug resistance has become a main burden in the treatment of S. sonnei infections and β-lactam antibiotics, such as pivmecillinam and ceftriaxone, are recommended to be used as second-line treatment. They work by inhibiting the biosynthesis of the peptidoglycan layer of bacterial cell walls, in which the final transpeptidation step is facilitated by penicillin-binding proteins (PBPs). In this study, using protein homology modelling, we modelled the structure of PBP6 from S. sonnei and comprehensively examined the molecular interactions between PBP6 and its pentapeptide substrate and two antibiotic inhibitors. The docked complex of S. sonnei PBP6 with pentapeptides showed that the substrate bound to the active site groove of the DD-carboxypeptidase domain, via hydrogen bonding interactions with the residues S79, V80, Q101, G144, D146 and R240, in close proximity to the catalytic nucleophile S36 for the nucleophilic attack. Two residues, R240 and T208, were found to be important in ligand recognition and binding, where they formed strong hydrogen bonds with the substrate and β-lactams, respectively. Our results provide valuable information on the molecular interactions essential for ligand recognition and catalysis by PBP6. Understanding these interactions will be helpful in the development of effective drugs to treat S. sonnei infections.
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16
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Graham CLB, Newman H, Gillett FN, Smart K, Briggs N, Banzhaf M, Roper DI. A Dynamic Network of Proteins Facilitate Cell Envelope Biogenesis in Gram-Negative Bacteria. Int J Mol Sci 2021; 22:12831. [PMID: 34884635 PMCID: PMC8657477 DOI: 10.3390/ijms222312831] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Revised: 11/02/2021] [Accepted: 11/03/2021] [Indexed: 01/01/2023] Open
Abstract
Bacteria must maintain the ability to modify and repair the peptidoglycan layer without jeopardising its essential functions in cell shape, cellular integrity and intermolecular interactions. A range of new experimental techniques is bringing an advanced understanding of how bacteria regulate and achieve peptidoglycan synthesis, particularly in respect of the central role played by complexes of Sporulation, Elongation or Division (SEDs) and class B penicillin-binding proteins required for cell division, growth and shape. In this review we highlight relationships implicated by a bioinformatic approach between the outer membrane, cytoskeletal components, periplasmic control proteins, and cell elongation/division proteins to provide further perspective on the interactions of these cell division, growth and shape complexes. We detail the network of protein interactions that assist in the formation of peptidoglycan and highlight the increasingly dynamic and connected set of protein machinery and macrostructures that assist in creating the cell envelope layers in Gram-negative bacteria.
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Affiliation(s)
- Chris L. B. Graham
- School of Life Sciences, University of Warwick, Coventry CV4 7AL, UK; (C.L.B.G.); (H.N.); (F.N.G.); (K.S.); (N.B.)
| | - Hector Newman
- School of Life Sciences, University of Warwick, Coventry CV4 7AL, UK; (C.L.B.G.); (H.N.); (F.N.G.); (K.S.); (N.B.)
| | - Francesca N. Gillett
- School of Life Sciences, University of Warwick, Coventry CV4 7AL, UK; (C.L.B.G.); (H.N.); (F.N.G.); (K.S.); (N.B.)
- School of Biosciences, University of Birmingham, Birmingham B15 2TT, UK;
| | - Katie Smart
- School of Life Sciences, University of Warwick, Coventry CV4 7AL, UK; (C.L.B.G.); (H.N.); (F.N.G.); (K.S.); (N.B.)
| | - Nicholas Briggs
- School of Life Sciences, University of Warwick, Coventry CV4 7AL, UK; (C.L.B.G.); (H.N.); (F.N.G.); (K.S.); (N.B.)
| | - Manuel Banzhaf
- School of Biosciences, University of Birmingham, Birmingham B15 2TT, UK;
| | - David I. Roper
- School of Life Sciences, University of Warwick, Coventry CV4 7AL, UK; (C.L.B.G.); (H.N.); (F.N.G.); (K.S.); (N.B.)
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17
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Workman SD, Day J, Farha MA, El Zahed SS, Bon C, Brown ED, Organ MG, Strynadka NCJ. Structural Insights into the Inhibition of Undecaprenyl Pyrophosphate Synthase from Gram-Positive Bacteria. J Med Chem 2021; 64:13540-13550. [PMID: 34473495 DOI: 10.1021/acs.jmedchem.1c00941] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The polyprenyl lipid undecaprenyl phosphate (C55P) is the universal carrier lipid for the biosynthesis of bacterial cell wall polymers. C55P is synthesized in its pyrophosphate form by undecaprenyl pyrophosphate synthase (UppS), an essential cis-prenyltransferase that is an attractive target for antibiotic development. We previously identified a compound (MAC-0547630) that showed promise as a novel class of inhibitor and an ability to potentiate β-lactam antibiotics. Here, we provide a structural model for MAC-0547630's inhibition of UppS and a structural rationale for its enhanced effect on UppS from Bacillus subtilis versus Staphylococcus aureus. We also describe the synthesis of a MAC-0547630 derivative (JPD447), show that it too can potentiate β-lactam antibiotics, and provide a structural rationale for its improved potentiation. Finally, we present an improved structural model of clomiphene's inhibition of UppS. Taken together, our data provide a foundation for structure-guided drug design of more potent UppS inhibitors in the future.
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Affiliation(s)
- Sean D Workman
- Department of Biochemistry and Molecular Biology, University of British Columbia, 2350 Health Sciences Mall, Vancouver, British Columbia V6T 1Z3, Canada.,Centre for Blood Research, University of British Columbia, 2350 Health Sciences Mall, Vancouver, British Columbia V6T 1Z3, Canada
| | - Jonathan Day
- Department of Chemistry, York University, 4700 Keele Street, Toronto, Ontario M3J 1P3, Canada
| | - Maya A Farha
- Department of Biochemistry and Biomedical Sciences, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4K1, Canada.,Michael G. DeGroote Institute of Infectious Disease Research, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4L8, Canada
| | - Sara S El Zahed
- Department of Biochemistry and Biomedical Sciences, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4K1, Canada.,Michael G. DeGroote Institute of Infectious Disease Research, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4L8, Canada
| | - Chris Bon
- Department of Biochemistry and Molecular Biology, University of British Columbia, 2350 Health Sciences Mall, Vancouver, British Columbia V6T 1Z3, Canada.,Centre for Blood Research, University of British Columbia, 2350 Health Sciences Mall, Vancouver, British Columbia V6T 1Z3, Canada
| | - Eric D Brown
- Department of Biochemistry and Biomedical Sciences, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4K1, Canada.,Michael G. DeGroote Institute of Infectious Disease Research, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4L8, Canada
| | - Michael G Organ
- Department of Chemistry, York University, 4700 Keele Street, Toronto, Ontario M3J 1P3, Canada.,Centre for Catalysis Research and Innovation, University of Ottawa, 30 Marie-Curie Private, Ottawa, Ontario K1N 6N5, Canada.,Department of Chemistry and Biomolecular Sciences, University of Ottawa, 150 Louis-Pasteur Private, Ottawa, Ontario K1N 6N5, Canada
| | - Natalie C J Strynadka
- Department of Biochemistry and Molecular Biology, University of British Columbia, 2350 Health Sciences Mall, Vancouver, British Columbia V6T 1Z3, Canada.,Centre for Blood Research, University of British Columbia, 2350 Health Sciences Mall, Vancouver, British Columbia V6T 1Z3, Canada
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18
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Voedts H, Dorchêne D, Lodge A, Vollmer W, Arthur M, Hugonnet JE. Role of endopeptidases in peptidoglycan synthesis mediated by alternative cross-linking enzymes in Escherichia coli. EMBO J 2021; 40:e108126. [PMID: 34382698 DOI: 10.15252/embj.2021108126] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Revised: 07/22/2021] [Accepted: 07/24/2021] [Indexed: 12/20/2022] Open
Abstract
Bacteria resist to the turgor pressure of the cytoplasm through a net-like macromolecule, the peptidoglycan, made of glycan strands connected via peptides cross-linked by penicillin-binding proteins (PBPs). We recently reported the emergence of β-lactam resistance resulting from a bypass of PBPs by the YcbB L,D-transpeptidase (LdtD), which form chemically distinct 3→3 cross-links compared to 4→3 formed by PBPs. Here we show that peptidoglycan expansion requires controlled hydrolysis of cross-links and identify among eight endopeptidase paralogues the minimum enzyme complements essential for bacterial growth with 4→3 (MepM) and 3→3 (MepM and MepK) cross-links. Purified Mep endopeptidases unexpectedly displayed a 4→3 and 3→3 dual specificity implying recognition of a common motif in the two cross-link types. Uncoupling of the polymerization of glycan chains from the 4→3 cross-linking reaction was found to facilitate the bypass of PBPs by YcbB. These results illustrate the plasticity of the peptidoglycan polymerization machinery in response to the selective pressure of β-lactams.
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Affiliation(s)
- Henri Voedts
- Centre de Recherche des Cordeliers, Sorbonne Université, Inserm, Université de Paris, Paris, France
| | - Delphine Dorchêne
- Centre de Recherche des Cordeliers, Sorbonne Université, Inserm, Université de Paris, Paris, France
| | - Adam Lodge
- Centre for Bacterial Cell Biology, Biosciences Institute, Newcastle University, Newcastle Upon Tyne, UK
| | - Waldemar Vollmer
- Centre for Bacterial Cell Biology, Biosciences Institute, Newcastle University, Newcastle Upon Tyne, UK
| | - Michel Arthur
- Centre de Recherche des Cordeliers, Sorbonne Université, Inserm, Université de Paris, Paris, France
| | - Jean-Emmanuel Hugonnet
- Centre de Recherche des Cordeliers, Sorbonne Université, Inserm, Université de Paris, Paris, France
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19
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Aliashkevich A, Cava F. LD-transpeptidases: the great unknown among the peptidoglycan cross-linkers. FEBS J 2021; 289:4718-4730. [PMID: 34109739 DOI: 10.1111/febs.16066] [Citation(s) in RCA: 38] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2021] [Revised: 05/05/2021] [Accepted: 06/09/2021] [Indexed: 12/24/2022]
Abstract
The peptidoglycan (PG) cell wall is an essential polymer for the shape and viability of bacteria. Its protective role is in great part provided by its mesh-like character. Therefore, PG-cross-linking enzymes like the penicillin-binding proteins (PBPs) are among the best targets for antibiotics. However, while PBPs have been in the spotlight for more than 50 years, another class of PG-cross-linking enzymes called LD-transpeptidases (LDTs) seemed to contribute less to PG synthesis and, thus, has kept an aura of mystery. In the last years, a number of studies have associated LDTs with cell wall adaptation to stress including β-lactam antibiotics, outer membrane stability, and toxin delivery, which has shed light onto the biological meaning of these proteins. Furthermore, as some species display a great abundance of LD-cross-links in their cell wall, it has been hypothesized that LDTs could also be the main synthetic PG-transpeptidases in some bacteria. In this review, we introduce these enzymes and their role in PG biosynthesis and we highlight the most recent advances in understanding their biological role in diverse species.
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Affiliation(s)
- Alena Aliashkevich
- Department of Molecular Biology and Laboratory for Molecular Infection Medicine Sweden, Umeå Centre for Microbial Research, Umeå University, Sweden
| | - Felipe Cava
- Department of Molecular Biology and Laboratory for Molecular Infection Medicine Sweden, Umeå Centre for Microbial Research, Umeå University, Sweden
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20
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CryoEM structure of the antibacterial target PBP1b at 3.3 Å resolution. Nat Commun 2021; 12:2775. [PMID: 33986273 PMCID: PMC8119973 DOI: 10.1038/s41467-021-23063-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Accepted: 03/25/2021] [Indexed: 12/02/2022] Open
Abstract
The pathway for the biosynthesis of the bacterial cell wall is one of the most prolific antibiotic targets, exemplified by the widespread use of β-lactam antibiotics. Despite this, our structural understanding of class A penicillin binding proteins, which perform the last two steps in this pathway, is incomplete due to the inherent difficulty in their crystallization and the complexity of their substrates. Here, we determine the near atomic resolution structure of the 83 kDa class A PBP from Escherichia coli, PBP1b, using cryogenic electron microscopy and a styrene maleic acid anhydride membrane mimetic. PBP1b, in its apo form, is seen to exhibit a distinct conformation in comparison to Moenomycin-bound crystal structures. The work herein paves the way for the use of cryoEM in structure-guided antibiotic development for this notoriously difficult to crystalize class of proteins and their complex substrates. Our structural understanding of class A penicillin binding proteins is incomplete due to the difficulty in their crystallization and the complexity of their substrates. Here, authors determine the structure of the 83 kDa class A PBP from Escherichia coli, PBP1b, using cryogenic electron microscopy and a styrene maleic acid anhydride membrane mimetic.
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21
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Caveney NA, Serapio-Palacios A, Woodward SE, Bozorgmehr T, Caballero G, Vuckovic M, Deng W, Finlay BB, Strynadka NCJ. Structural and Cellular Insights into the l,d-Transpeptidase YcbB as a Therapeutic Target in Citrobacter rodentium, Salmonella Typhimurium, and Salmonella Typhi Infections. Antimicrob Agents Chemother 2021; 65:e01592-20. [PMID: 33139287 PMCID: PMC7849009 DOI: 10.1128/aac.01592-20] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Accepted: 10/29/2020] [Indexed: 12/15/2022] Open
Abstract
The bacterial cell wall plays a key role in viability and is an important drug target. The cell wall is made of elongated polymers that are cross-linked to one another to form a load-bearing mesh. An alternative cell wall cross-linking mechanism used by the l,d-transpeptidase YcbB has been implicated in the stress-regulated roles of β-lactam resistance, outer membrane defect rescue, and typhoid toxin release. The role for this stress-linked cross-linking in the context of a host infection was unclear. Here, we resolve the crystallographic structures of both Salmonella Typhi YcbB and Citrobacter rodentium YcbB acylated with ertapenem that delineate the conserved structural characteristics of YcbB. In parallel, we show that the general involvement of YcbB in peptidoglycan reinforcement under conditions of bacterial outer envelope stress does not play a significant role in acute infections of mice by C. rodentium and S Typhimurium. Cumulatively, in this work we provide a foundation for the development of novel YcbB-specific antibacterial therapeutics to assist in treatment of increasingly drug-resistant S Typhi infections.
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Affiliation(s)
- N A Caveney
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia, Canada
- The Centre for Blood Research, University of British Columbia, Vancouver, British Columbia, Canada
| | - A Serapio-Palacios
- Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia, Canada
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada
| | - S E Woodward
- Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia, Canada
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada
| | - T Bozorgmehr
- Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia, Canada
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada
| | - G Caballero
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia, Canada
- The Centre for Blood Research, University of British Columbia, Vancouver, British Columbia, Canada
| | - M Vuckovic
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia, Canada
- The Centre for Blood Research, University of British Columbia, Vancouver, British Columbia, Canada
| | - W Deng
- Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia, Canada
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada
| | - B B Finlay
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia, Canada
- Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia, Canada
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada
| | - N C J Strynadka
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia, Canada
- The Centre for Blood Research, University of British Columbia, Vancouver, British Columbia, Canada
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22
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Septal Class A Penicillin-Binding Protein Activity and ld-Transpeptidases Mediate Selection of Colistin-Resistant Lipooligosaccharide-Deficient Acinetobacter baumannii. mBio 2021; 12:mBio.02185-20. [PMID: 33402533 PMCID: PMC8545086 DOI: 10.1128/mbio.02185-20] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Despite dogma suggesting that lipopolysaccharide/lipooligosaccharide (LOS) was essential for viability of Gram-negative bacteria, several Acinetobacter baumannii clinical isolates produced LOS− colonies after colistin selection. Inactivation of the conserved class A penicillin-binding protein, PBP1A, was a compensatory mutation that supported isolation of LOS−A. baumannii, but the impact of PBP1A mutation was not characterized. Here, we show that the absence of PBP1A causes septation defects and that these, together with ld-transpeptidase activity, support isolation of LOS−A. baumannii. PBP1A contributes to proper cell division in A. baumannii, and its absence induced cell chaining. Only isolates producing three or more septa supported selection of colistin-resistant LOS−A. baumannii. PBP1A was enriched at the midcell, where the divisome complex facilitates daughter cell formation, and its localization was dependent on glycosyltransferase activity. Transposon mutagenesis showed that genes encoding two putative ld-transpeptidases (LdtJ and LdtK) became essential in the PBP1A mutant. Both LdtJ and LdtK were required for selection of LOS−A. baumannii, but each had distinct enzymatic activities in the cell. Together, these findings demonstrate that defects in PBP1A glycosyltransferase activity and ld-transpeptidase activity remodel the cell envelope to support selection of colistin-resistant LOS−A. baumannii.
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23
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Abstract
Bacteria surround their cell membrane with a net-like peptidoglycan layer, called sacculus, to protect the cell from bursting and maintain its cell shape. Sacculus growth during elongation and cell division is mediated by dynamic and transient multiprotein complexes, the elongasome and divisome, respectively. In this Review we present our current understanding of how peptidoglycan synthases are regulated by multiple and specific interactions with cell morphogenesis proteins that are linked to a dynamic cytoskeletal protein, either the actin-like MreB or the tubulin-like FtsZ. Several peptidoglycan synthases and hydrolases require activation by outer-membrane-anchored lipoproteins. We also discuss how bacteria achieve robust cell wall growth under different conditions and stresses by maintaining multiple peptidoglycan enzymes and regulators as well as different peptidoglycan growth mechanisms, and we present the emerging role of LD-transpeptidases in peptidoglycan remodelling.
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24
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Fodje M, Mundboth K, Labiuk S, Janzen K, Gorin J, Spasyuk D, Colville S, Grochulski P. Macromolecular crystallography beamlines at the Canadian Light Source: building on success. Acta Crystallogr D Struct Biol 2020; 76:630-635. [PMID: 32627736 PMCID: PMC7336384 DOI: 10.1107/s2059798320007603] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Accepted: 06/04/2020] [Indexed: 11/30/2022] Open
Abstract
The Canadian Macromolecular Crystallography Facility (CMCF) consists of two beamlines dedicated to macromolecular crystallography: CMCF-ID and CMCF-BM. After the first experiments were conducted in 2006, the facility has seen a sharp increase in usage and has produced a significant amount of data for the Canadian crystallographic community. Upgrades aimed at increasing throughput and flux to support the next generation of more demanding experiments are currently under way or have recently been completed. At CMCF-BM, this includes an enhanced monochromator, automounter software upgrades and a much faster detector. CMCF-ID will receive a major upgrade including a new undulator, a new monochromator and new optics to stably focus the beam onto a smaller sample size, as well as a brand-new detector.
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Affiliation(s)
- Michel Fodje
- Canadian Macromolecular Crystallography Facility, Canadian Light Source, 44 Innovation Boulevard, Saskatoon, SK S7N 2V3, Canada
| | - Kiran Mundboth
- Canadian Macromolecular Crystallography Facility, Canadian Light Source, 44 Innovation Boulevard, Saskatoon, SK S7N 2V3, Canada
| | - Shaunivan Labiuk
- Canadian Macromolecular Crystallography Facility, Canadian Light Source, 44 Innovation Boulevard, Saskatoon, SK S7N 2V3, Canada
| | - Kathryn Janzen
- Canadian Macromolecular Crystallography Facility, Canadian Light Source, 44 Innovation Boulevard, Saskatoon, SK S7N 2V3, Canada
| | - James Gorin
- Canadian Macromolecular Crystallography Facility, Canadian Light Source, 44 Innovation Boulevard, Saskatoon, SK S7N 2V3, Canada
| | - Denis Spasyuk
- Canadian Macromolecular Crystallography Facility, Canadian Light Source, 44 Innovation Boulevard, Saskatoon, SK S7N 2V3, Canada
| | - Scott Colville
- Canadian Macromolecular Crystallography Facility, Canadian Light Source, 44 Innovation Boulevard, Saskatoon, SK S7N 2V3, Canada
| | - Pawel Grochulski
- Canadian Macromolecular Crystallography Facility, Canadian Light Source, 44 Innovation Boulevard, Saskatoon, SK S7N 2V3, Canada
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25
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A Family of T6SS Antibacterial Effectors Related to l,d-Transpeptidases Targets the Peptidoglycan. Cell Rep 2020; 31:107813. [DOI: 10.1016/j.celrep.2020.107813] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Revised: 04/20/2020] [Accepted: 06/03/2020] [Indexed: 12/17/2022] Open
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