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Peñalver M, Paradela A, Palacios-Cuéllar C, Pucciarelli MG, García-Del Portillo F. Experimental evidence of d-glutamate racemase activity in the uncultivated bacterium Candidatus Saccharimonas aalborgensis. Environ Microbiol 2024; 26:e16621. [PMID: 38558504 DOI: 10.1111/1462-2920.16621] [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: 01/29/2024] [Accepted: 03/16/2024] [Indexed: 04/04/2024]
Abstract
The Candidate Phyla Radiation (CPR) encompasses widespread uncultivated bacteria with reduced genomes and limited metabolic capacities. Most CPR bacteria lack the minimal set of enzymes required for peptidoglycan (PG) synthesis, leaving it unclear how these bacteria produce this essential envelope component. In this study, we analysed the distribution of d-amino acid racemases that produce the universal PG components d-glutamate (d-Glu) or d-alanine (d-Ala). We also examined moonlighting enzymes that synthesize d-Glu or d-Ala. Unlike other phyla in the domain Bacteria, CPR bacteria do not exhibit these moonlighting activities and have, at most, one gene encoding either a Glu or Ala racemase. One of these 'orphan' racemases is a predicted Glu racemase (MurICPR) from the CPR bacterium Candidatus Saccharimonas aalborgenesis. The expression of MurICPR restores the growth of a Salmonella d-Glu auxotroph lacking its endogenous racemase and results in the substitution of l-Ala by serine as the first residue in a fraction of the PG stem peptides. In vitro, MurICPR exclusively racemizes Glu as a substrate. Therefore, Ca. Saccharimonas aalborgensis may couple Glu racemization to serine and d-Glu incorporation into the stem peptide. Our findings provide the first insights into the synthesis of PG by an uncultivated environmental bacterium and illustrate how to experimentally test enzymatic activities from CPR bacteria related to PG metabolism.
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Affiliation(s)
- Marcos Peñalver
- Laboratory of Intracellular Bacterial Pathogens, National Centre for Biotechnology (CNB-CSIC), Madrid, Spain
- Department of Molecular Biology, Universidad Autónoma de Madrid (UAM), Madrid, Spain
- Centro de Biologia Molecular Severo Ochoa (CBM), CSIC-UAM, Madrid, Spain
| | - Alberto Paradela
- Proteomics Facility, National Centre for Biotechnology (CNB-CSIC), Madrid, Spain
| | - César Palacios-Cuéllar
- Laboratory of Intracellular Bacterial Pathogens, National Centre for Biotechnology (CNB-CSIC), Madrid, Spain
| | - M Graciela Pucciarelli
- Laboratory of Intracellular Bacterial Pathogens, National Centre for Biotechnology (CNB-CSIC), Madrid, Spain
- Department of Molecular Biology, Universidad Autónoma de Madrid (UAM), Madrid, Spain
- Centro de Biologia Molecular Severo Ochoa (CBM), CSIC-UAM, Madrid, Spain
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Umetsu S, Tsunoda T, Kiyanagi H, Inahashi Y, Nonaka K, Dairi T, Ogasawara Y. Identification of a new oligomycin derivative as a specific inhibitor of the alternative peptidoglycan biosynthetic pathway. J Antibiot (Tokyo) 2024; 77:182-184. [PMID: 38200161 DOI: 10.1038/s41429-023-00693-0] [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: 07/14/2023] [Revised: 11/15/2023] [Accepted: 11/19/2023] [Indexed: 01/12/2024]
Abstract
Peptidoglycan is an important macromolecule in bacterial cell walls to maintain cell integrity, and its biosynthetic pathway has been well studied. Recently, we demonstrated that some bacteria such as Xanthomonas oryzae, a pathogen causing bacterial blight of rice, used an alternative pathway for peptidoglycan biosynthesis. In this pathway, MurD2, a MurD homolog, catalyzed the attachment of L-Glu to UDP-MurNAc-L-Ala and MurL, which did not show homology to any known protein, catalyzed epimerization of the terminal L-Glu of the MurD2 product to generate UDP-MurNAc-L-Ala-D-Glu. Because the alternative pathway also operates in some other plant pathogens and opportunistic pathogens, specific inhibitors of the alternative pathway could function as pesticides and antibiotics for these pathogens. In this study, we searched for specific inhibitors of the alternative pathway from metabolites produced by actinomycetes and identified a new oligomycin-class polyketide, which was revealed to inhibit the MurD2 reaction, in culture broth of Micromonospora sp. K18-0097.
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Affiliation(s)
- Shuhei Umetsu
- Graduate School of Chemical Sciences and Engineering, Hokkaido University, Sapporo, Hokkaido, 060-8628, Japan
| | - Takeshi Tsunoda
- Graduate School of Engineering, Hokkaido University, Sapporo, Hokkaido, 060-8628, Japan
| | - Haruka Kiyanagi
- Graduate School of Chemical Sciences and Engineering, Hokkaido University, Sapporo, Hokkaido, 060-8628, Japan
| | - Yuki Inahashi
- Ōmura Satoshi Memorial Institute, Kitasato University, Minato-ku, Tokyo, 108-8641, Japan
| | - Kenichi Nonaka
- Ōmura Satoshi Memorial Institute, Kitasato University, Minato-ku, Tokyo, 108-8641, Japan
| | - Tohru Dairi
- Graduate School of Engineering, Hokkaido University, Sapporo, Hokkaido, 060-8628, Japan.
| | - Yasushi Ogasawara
- Graduate School of Engineering, Hokkaido University, Sapporo, Hokkaido, 060-8628, Japan.
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Ogasawara Y, Dairi T. Discovery of an alternative pathway of peptidoglycan biosynthesis: A new target for pathway specific inhibitors. J Ind Microbiol Biotechnol 2021; 48:6296644. [PMID: 34114638 PMCID: PMC8788868 DOI: 10.1093/jimb/kuab038] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Accepted: 06/07/2021] [Indexed: 11/13/2022]
Abstract
Peptidoglycan in bacterial cell walls is a biopolymer consisting of sugars and amino acids and plays important role in maintaining cell integrity from the environment. Its biosynthesis is a major target for antibiotics and the genes and enzymes involved in the biosynthetic pathway have been well studied. However, we recently identified an alternative pathway in the early stage of peptidoglycan biosynthesis in Xanthomonas oryzae, a plant pathogen causing bacterial blight disease of rice. The distribution of the alternative pathway is limited to relatively few bacterial genera that contain many pathogenic species, including Xylella and Stenotrophomonas, besides Xanthomonas. Thus, the alternative pathway is an attractive target for the development of narrow spectrum antibiotics specific to pathogens. In this minireview, we summarize the discovery of the alternative pathway and identification of its specific inhibitors.
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Affiliation(s)
- Yasushi Ogasawara
- Graduate School of Engineering, Hokkaido University, N13 & W8, Kita-ku, Sapporo, Hokkaido 060-8628, Japan
| | - Tohru Dairi
- Graduate School of Engineering, Hokkaido University, N13 & W8, Kita-ku, Sapporo, Hokkaido 060-8628, Japan
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Flavonoids from Woodfordia fruticosa as potential SmltD inhibitors in the alternative biosynthetic pathway of peptidoglycan. Bioorg Med Chem Lett 2021; 36:127787. [DOI: 10.1016/j.bmcl.2021.127787] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2020] [Revised: 12/27/2020] [Accepted: 01/09/2021] [Indexed: 11/22/2022]
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Identification of actinomycin D as a specific inhibitor of the alternative pathway of peptidoglycan biosynthesis. J Antibiot (Tokyo) 2019; 73:125-127. [DOI: 10.1038/s41429-019-0252-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Accepted: 10/09/2019] [Indexed: 11/08/2022]
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Ogasawara Y, Shigematsu M, Sato S, Kato H, Dairi T. Involvement of Peptide Epimerization in Poly-γ-glutamic Acid Biosynthesis. Org Lett 2019; 21:3972-3975. [PMID: 31090431 DOI: 10.1021/acs.orglett.9b01121] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Poly-γ-glutamic acid (PGA) is a promising polymer that comprises d- and l-glutamic acid (Glu) connected via an amide bond. PGA is biosynthesized by a transmembrane enzyme complex composed of PgsB, PgsC, and PgsA. However, the detailed reaction, especially the mechanism for introducing d-Glu residues into PGA, remains elusive. We herein report isotope tracer experiments with deuterated l- and d-Glu and demonstrate that epimerization of a growing peptide is involved in PGA biosynthesis.
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Affiliation(s)
- Yasushi Ogasawara
- Graduate School of Engineering , Hokkaido University , Sapporo , Hokkaido 060-8628 , Japan
| | - Mayuko Shigematsu
- Graduate School of Engineering , Hokkaido University , Sapporo , Hokkaido 060-8628 , Japan
| | - Shota Sato
- Graduate School of Engineering , Hokkaido University , Sapporo , Hokkaido 060-8628 , Japan
| | - Hinata Kato
- Graduate School of Engineering , Hokkaido University , Sapporo , Hokkaido 060-8628 , Japan
| | - Tohru Dairi
- Graduate School of Engineering , Hokkaido University , Sapporo , Hokkaido 060-8628 , Japan
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Feng R, Satoh Y, Morita H, Ogasawara Y, Dairi T. Amino Acid Residues Recognizing Isomeric Glutamate Substrates in UDP- N-acetylmuramic acid-l-alanine-glutamate Synthetases. ACS Chem Biol 2019; 14:975-978. [PMID: 30977993 DOI: 10.1021/acschembio.9b00159] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
We recently revealed that a previously unknown pathway for peptidoglycan biosynthesis operates in some microorganisms, including Xanthomonas oryzae. It involves two enzymes, MurD2 and MurL, which catalyze the ligation of l-glutamate (l-Glu) to UDP- N-acetylmuramic acid-l-alanine and the epimerization of the terminal l-Glu of the product, respectively. MurD2 of X. oryzae possesses a 26% identity with MurD of Escherichia coli (MurDec), which ligates d-Glu to UDP- N-acetylmuramic acid-l-alanine. To understand how X. oryzae MurD2 recognizes the isomer substrate, we estimated its structure based on that of MurDec during docking simulations. Several amino acid residues, which may be responsible for l-Glu recognition, were replaced with their corresponding amino acid residues in MurDec. Consequently, we obtained a mutated MurD2 enzyme that contained two amino acid substitutions and accepted only d-Glu as the substrate. We next tried to convert the substrate specificity of MurDec using the same strategy, but the mutant enzyme still accepted only d-Glu. Then, MurD of Streptococcus mutans (MurDsm), which possesses the key amino acid residue for l-Glu recognition identified in MurD2, was used for random screenings of mutant enzymes accepting l-Glu. We obtained a mutated MurDsm that had one amino acid substitution and slightly accepted l-Glu. A mutated MurDec possessing the corresponding one amino acid substitution also accepted l-Glu. Thus, we revealed that a few amino acid residues in MurD/MurD2 might control the acceptability of substrates with different stereochemistries.
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Affiliation(s)
- Ruoyin Feng
- Graduate School of Chemical Sciences and Engineering, Hokkaido University, N13-W8, Kita-ku, Sapporo, Hokkaido 060-8628, Japan
| | - Yasuharu Satoh
- Graduate School of Engineering, Hokkaido University, N13-W8, Kita-ku, Sapporo, Hokkaido 060-8628, Japan
| | - Hiroyuki Morita
- Institute of Natural Medicine, University of Toyama, 2630-Sugitani, Toyama 930-0194, Japan
| | - Yasushi Ogasawara
- Graduate School of Engineering, Hokkaido University, N13-W8, Kita-ku, Sapporo, Hokkaido 060-8628, Japan
| | - Tohru Dairi
- Graduate School of Engineering, Hokkaido University, N13-W8, Kita-ku, Sapporo, Hokkaido 060-8628, Japan
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Abstract
ABSTRACT
Peptides, biologically occurring oligomers of amino acids linked by amide bonds, are essential for living organisms. Many peptides isolated as natural products have biological functions such as antimicrobial, antivirus and insecticidal activities. Peptides often possess structural features or modifications not found in proteins, including the presence of nonproteinogenic amino acids, macrocyclic ring formation, heterocyclization, N-methylation and decoration by sugars or acyl groups. Nature employs various strategies to increase the structural diversity of peptides. Enzymes that modify peptides to yield mature natural products are of great interest for discovering new enzyme chemistry and are important for medicinal chemistry applications. We have discovered novel peptide modifying enzymes and have identified: (i) a new class of amide bond forming-enzymes; (ii) a pathway to biosynthesize a carbonylmethylene-containing pseudodipeptide structure; and (iii) two distinct peptide epimerases. In this review, an overview of our findings on peptide modifying enzymes is presented.
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Feng Z, Ogasawara Y, Nomura S, Dairi T. Biosynthetic Gene Cluster of ad-Tryptophan-Containing Lasso Peptide, MS-271. Chembiochem 2018; 19:2045-2048. [DOI: 10.1002/cbic.201800315] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Indexed: 01/31/2023]
Affiliation(s)
- Zhi Feng
- Graduate School of Engineering; Hokkaido University; Sapporo Hokkaido 060-8628 Japan
| | - Yasushi Ogasawara
- Graduate School of Engineering; Hokkaido University; Sapporo Hokkaido 060-8628 Japan
| | - Satoshi Nomura
- Graduate School of Engineering; Hokkaido University; Sapporo Hokkaido 060-8628 Japan
| | - Tohru Dairi
- Graduate School of Engineering; Hokkaido University; Sapporo Hokkaido 060-8628 Japan
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Ogasawara Y, Dairi T. Peptide Epimerization Machineries Found in Microorganisms. Front Microbiol 2018; 9:156. [PMID: 29467749 PMCID: PMC5808125 DOI: 10.3389/fmicb.2018.00156] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2017] [Accepted: 01/23/2018] [Indexed: 11/13/2022] Open
Abstract
D-Amino acid residues have been identified in peptides from a variety of eukaryotes and prokaryotes. In microorganisms, UDP-N-acetylmuramic acid pentapeptide (UDP-MurNAc-L-Ala-D-Glu-meso-diaminopimelate-D-Ala-D-Ala), a unit of peptidoglycan, is a representative. During its biosynthesis, D-Ala and D-Glu are generally supplied by racemases from the corresponding isomers. However, we recently identified a unique unidirectional L-Glu epimerase catalyzing the epimerization of the terminal L-Glu of UDP-MurNAc-L-Ala-L-Glu. Several such enzymes, introducing D-amino acid resides into peptides via epimerization, have been reported to date. This includes a L-Ala-D/L-Glu epimerase, which is possibly used during peptidoglycan degradation. In bacterial primary metabolisms, to the best of our knowledge, these two machineries are the only examples of peptide epimerization. However, a variety of peptides containing D-amino acid residues have been isolated from microorganisms as secondary metabolites. Their biosynthetic mechanisms have been studied and three different peptide epimerization machineries have been reported. The first is non-ribosomal peptide synthetase (NRPS). Excellent studies with dissected modules of gramicidin synthetase and tyrocidine synthetase revealed the reactions of the epimerization domains embedded in the enzymes. The obtained information is still utilized to predict epimerization domains in uncharacterized NRPSs. The second includes the biosynthetic enzymes of lantibiotics, which are ribosome-dependently supplied peptide antibiotics containing polycyclic thioether amino acids (lanthionines). A mechanism for the formation of the D-Ala moiety in lanthionine by two enzymes, dehydratases catalyzing the conversion of L-Ser into dehydroalanine and enzymes catalyzing nucleophilic attack of the thiol of cysteine into dehydroalanine, was clarified. Similarly, the formation of a D-Ala residue by reduction of the dehydroalanine residue was also reported. The last type of machinery includes radical-S-adenosylmethionine (rSAM)-dependent enzymes, which catalyze a variety of radical-mediated chemical transformations. In the biosynthesis of polytheonamide, a marine sponge-derived and ribosome-dependently supplied peptide composed of 48 amino acids, a rSAM enzyme (PoyD) is responsible for unidirectional epimerizations of multiple different amino acids in the precursor peptide. In this review, we briefly summarize the discovery and current mechanistic understanding of these peptide epimerization enzymes.
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Affiliation(s)
| | - Tohru Dairi
- Graduate School of Engineering, Hokkaido University, Sapporo, Japan
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