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Koatale P, Welling MM, Ndlovu H, Kgatle M, Mdanda S, Mdlophane A, Okem A, Takyi-Williams J, Sathekge MM, Ebenhan T. Insights into Peptidoglycan-Targeting Radiotracers for Imaging Bacterial Infections: Updates, Challenges, and Future Perspectives. ACS Infect Dis 2024; 10:270-286. [PMID: 38290525 PMCID: PMC10862554 DOI: 10.1021/acsinfecdis.3c00443] [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: 08/28/2023] [Revised: 12/16/2023] [Accepted: 12/18/2023] [Indexed: 02/01/2024]
Abstract
The unique structural architecture of the peptidoglycan allows for the stratification of bacteria as either Gram-negative or Gram-positive, which makes bacterial cells distinguishable from mammalian cells. This classification has received attention as a potential target for diagnostic and therapeutic purposes. Bacteria's ability to metabolically integrate peptidoglycan precursors during cell wall biosynthesis and recycling offers an opportunity to target and image pathogens in their biological state. This Review explores the peptidoglycan biosynthesis for bacteria-specific targeting for infection imaging. Current and potential radiolabeled peptidoglycan precursors for bacterial infection imaging, their development status, and their performance in vitro and/or in vivo are highlighted. We conclude by providing our thoughts on how to shape this area of research for future clinical translation.
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Affiliation(s)
- Palesa
C. Koatale
- Department
of Nuclear Medicine, University of Pretoria, 0001 Pretoria, South Africa
- Nuclear
Medicine Research Infrastructure (NuMeRI) NPC, 0001 Pretoria, South Africa
| | - Mick M. Welling
- Interventional
Molecular Imaging Laboratory, Department of Radiology, Leiden University Medical Center, 2333 ZA Leiden, The Netherlands
| | - Honest Ndlovu
- Department
of Nuclear Medicine, University of Pretoria, 0001 Pretoria, South Africa
- Nuclear
Medicine Research Infrastructure (NuMeRI) NPC, 0001 Pretoria, South Africa
| | - Mankgopo Kgatle
- Department
of Nuclear Medicine, University of Pretoria, 0001 Pretoria, South Africa
- Nuclear
Medicine Research Infrastructure (NuMeRI) NPC, 0001 Pretoria, South Africa
| | - Sipho Mdanda
- Department
of Nuclear Medicine, University of Pretoria, 0001 Pretoria, South Africa
- Nuclear
Medicine Research Infrastructure (NuMeRI) NPC, 0001 Pretoria, South Africa
| | - Amanda Mdlophane
- Department
of Nuclear Medicine, University of Pretoria, 0001 Pretoria, South Africa
- Nuclear
Medicine Research Infrastructure (NuMeRI) NPC, 0001 Pretoria, South Africa
| | - Ambrose Okem
- Department
of Anaesthesia, School of Clinical Medicine, University of Witwatersrand, 2050 Johannesburg, South Africa
| | - John Takyi-Williams
- Pharmacokinetic
and Mass Spectrometry Core, College of Pharmacy, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Mike M. Sathekge
- Department
of Nuclear Medicine, University of Pretoria, 0001 Pretoria, South Africa
- Nuclear
Medicine Research Infrastructure (NuMeRI) NPC, 0001 Pretoria, South Africa
| | - Thomas Ebenhan
- Department
of Nuclear Medicine, University of Pretoria, 0001 Pretoria, South Africa
- Nuclear
Medicine Research Infrastructure (NuMeRI) NPC, 0001 Pretoria, South Africa
- DSI/NWU Pre-clinical
Drug Development Platform, North West University, 2520 Potchefstroom, South Africa
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2
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Ackroyd BK, Dodson EJ, Mehboob J, Dowle AA, Thomas GH, Wilkinson AJ. Structure and ligand binding in the putative anti-microbial peptide transporter protein, YejA. MICROBIOLOGY (READING, ENGLAND) 2024; 170:001430. [PMID: 38334478 PMCID: PMC10924461 DOI: 10.1099/mic.0.001430] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2023] [Accepted: 01/19/2024] [Indexed: 02/10/2024]
Abstract
YejABEF is an ATP-binding cassette transporter that is implicated in the sensitivity of Escherichia coli to anti-microbial peptides, the best-characterized example being microcin C, a peptide-nucleotide antibiotic that targets aspartyl-tRNA synthetase. Here the structure of the extracellular solute binding protein, YejA, has been determined, revealing an oligopeptide-binding protein fold enclosing a ligand-binding pocket larger than those of other peptide-binding proteins of known structure. Prominent electron density in this cavity defines an undecapeptide sequence LGEPRYAFNFN, an observation that is confirmed by mass spectrometry. In the structure, the peptide interactions with the protein are mediated by main chain hydrogen bonds with the exception of Arg5 whose guanidinium side chain makes a set of defining polar interactions with four YejA residues. More detailed characterization of purified recombinant YejA, by a combination of ESI and MALDI-mass spectrometry as well as thermal shift assays, reveals a set of YejA complexes containing overlapping peptides 10-19 residues in length. All contain the sequence LGEPRYAFN. Curiously, these peptides correspond to residues 8-26 of the mature YejA protein, which belong to a unique N-terminal extension that distinguishes YejA from other cluster C oligopeptide binding proteins of known structure. This 35-residue extension is well-ordered and packs across the surface of the protein. The undecapeptide ligand occupies only a fraction of the enclosed pocket volume suggesting the possibility that much larger peptides or peptide conjugates could be accommodated, though thermal shift assays of YejA binding to antimicrobial peptides and peptides unrelated to LGEPRYAFNFN have not provided evidence of binding. While the physiological significance of this 'auto-binding' is not clear, the experimental data suggest that it is not an artefact of the crystallization process and that it may have a function in the sensing of periplasmic or membrane stress.
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Affiliation(s)
- Bryony K. Ackroyd
- York Structural Biology Laboratory and York Biomedical Research Institute, Department of Chemistry, University of York, York YO10 5DD, UK
- Department of Biology and York Biomedical Research Institute, University of York, York YO10 5DD, UK
| | - Eleanor J. Dodson
- York Structural Biology Laboratory and York Biomedical Research Institute, Department of Chemistry, University of York, York YO10 5DD, UK
| | - Javeria Mehboob
- Department of Biology and York Biomedical Research Institute, University of York, York YO10 5DD, UK
| | - Adam A. Dowle
- Bioscience Technology Facility, Department of Biology, University of York, York YO10 5DD, UK
| | - Gavin H. Thomas
- Department of Biology and York Biomedical Research Institute, University of York, York YO10 5DD, UK
| | - Anthony J. Wilkinson
- York Structural Biology Laboratory and York Biomedical Research Institute, Department of Chemistry, University of York, York YO10 5DD, UK
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Kwan JMC, Qiao Y. Mechanistic Insights into the Activities of Major Families of Enzymes in Bacterial Peptidoglycan Assembly and Breakdown. Chembiochem 2023; 24:e202200693. [PMID: 36715567 DOI: 10.1002/cbic.202200693] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2022] [Revised: 01/28/2023] [Accepted: 01/30/2023] [Indexed: 01/31/2023]
Abstract
Serving as an exoskeletal scaffold, peptidoglycan is a polymeric macromolecule that is essential and conserved across all bacteria, yet is absent in mammalian cells; this has made bacterial peptidoglycan a well-established excellent antibiotic target. In addition, soluble peptidoglycan fragments derived from bacteria are increasingly recognised as key signalling molecules in mediating diverse intra- and inter-species communication in nature, including in gut microbiota-host crosstalk. Each bacterial species encodes multiple redundant enzymes for key enzymatic activities involved in peptidoglycan assembly and breakdown. In this review, we discuss recent findings on the biochemical activities of major peptidoglycan enzymes, including peptidoglycan glycosyltransferases (PGT) and transpeptidases (TPs) in the final stage of peptidoglycan assembly, as well as peptidoglycan glycosidases, lytic transglycosylase (LTs), amidases, endopeptidases (EPs) and carboxypeptidases (CPs) in peptidoglycan turnover and metabolism. Biochemical characterisation of these enzymes provides valuable insights into their substrate specificity, regulation mechanisms and potential modes of inhibition.
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Affiliation(s)
- Jeric Mun Chung Kwan
- School of Chemistry, Chemical Engineering and Biotechnology (CCEB), 21 Nanyang Link, Singapore, 637371, Singapore.,LKC School of Medicine, Nanyang Technological University (NTU) Singapore, 11 Mandalay Road, Singapore, Singapore, 208232, Singapore
| | - Yuan Qiao
- School of Chemistry, Chemical Engineering and Biotechnology (CCEB), Nanyang Technological University (NTU), Singapore, 21 Nanyang Link, Singapore, 637371, Singapore
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4
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Thomas GH. Microbial Musings - Winter 2022. MICROBIOLOGY (READING, ENGLAND) 2022; 168:micro001310. [PMID: 36848206 PMCID: PMC10009517 DOI: 10.1099/mic.0.001310] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Indexed: 03/01/2023]
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Hughes AM, Darby JF, Dodson EJ, Wilson SJ, Turkenburg JP, Thomas GH, Wilkinson AJ. Peptide transport in Bacillus subtilis - structure and specificity in the extracellular solute binding proteins OppA and DppE. MICROBIOLOGY (READING, ENGLAND) 2022; 168. [PMID: 36748525 DOI: 10.1099/mic.0.001274] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Abstract
Peptide transporters play important nutritional and cell signalling roles in Bacillus subtilis, which are pronounced during stationary phase adaptations and development. Three high-affinity ATP-binding cassette (ABC) family transporters are involved in peptide uptake - the oligopeptide permease (Opp), another peptide permease (App) and a less well-characterized dipeptide permease (Dpp). Here we report crystal structures of the extracellular substrate binding proteins, OppA and DppE, which serve the Opp and Dpp systems, respectively. The structure of OppA was determined in complex with endogenous peptides, modelled as Ser-Asn-Ser-Ser, and with the sporulation-promoting peptide Ser-Arg-Asn-Val-Thr, which bind with K d values of 0.4 and 2 µM, respectively, as measured by isothermal titration calorimetry. Differential scanning fluorescence experiments with a wider panel of ligands showed that OppA has highest affinity for tetra- and penta-peptides. The structure of DppE revealed the unexpected presence of a murein tripeptide (MTP) ligand, l-Ala-d-Glu-meso-DAP, in the peptide binding groove. The mode of MTP binding in DppE is different to that observed in the murein peptide binding protein, MppA, from Escherichia coli, suggesting independent evolution of these proteins from an OppA-like precursor. The presence of MTP in DppE points to a role for Dpp in the uptake and recycling of cell wall peptides, a conclusion that is supported by analysis of the genomic context of dpp, which revealed adjacent genes encoding enzymes involved in muropeptide catabolism in a gene organization that is widely conserved in Firmicutes.
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Affiliation(s)
- Adam M Hughes
- Structural Biology Laboratory, Department of Chemistry, University of York, York YO10 5DD, UK
| | - John F Darby
- Structural Biology Laboratory, Department of Chemistry, University of York, York YO10 5DD, UK
| | - Eleanor J Dodson
- Structural Biology Laboratory, Department of Chemistry, University of York, York YO10 5DD, UK
| | - Samuel J Wilson
- Structural Biology Laboratory, Department of Chemistry, University of York, York YO10 5DD, UK
| | - Johan P Turkenburg
- Structural Biology Laboratory, Department of Chemistry, University of York, York YO10 5DD, UK
| | - Gavin H Thomas
- Department of Biology, University of York, York YO10 5DD, UK
| | - Anthony J Wilkinson
- Structural Biology Laboratory, Department of Chemistry, University of York, York YO10 5DD, UK
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6
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Brüser T, Mehner-Breitfeld D. Occurrence and potential mechanism of holin-mediated non-lytic protein translocation in bacteria. MICROBIAL CELL (GRAZ, AUSTRIA) 2022; 9:159-173. [PMID: 36262927 PMCID: PMC9527704 DOI: 10.15698/mic2022.10.785] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Revised: 09/13/2022] [Accepted: 09/15/2022] [Indexed: 11/13/2022]
Abstract
Holins are generally believed to generate large membrane lesions that permit the passage of endolysins across the cytoplasmic membrane of prokaryotes, ultimately resulting in cell wall degradation and cell lysis. However, there are more and more examples known for non-lytic holin-dependent secretion of proteins by bacteria, indicating that holins somehow can transport proteins without causing large membrane lesions. Phage-derived holins can be used for a non-lytic endolysin translocation to permeabilize the cell wall for the passage of secreted proteins. In addition, clostridia, which do not possess the Tat pathway for transport of folded proteins, most likely employ non-lytic holin-mediated transport also for secretion of toxins and bacteriocins that are incompatible with the general Sec pathway. The mechanism for non-lytic holin-mediated transport is unknown, but the recent finding that the small holin TpeE mediates a non-lytic toxin secretion in Clostridium perfringens opened new perspectives. TpeE contains only one short transmembrane helix that is followed by an amphipathic helix, which is reminiscent of TatA, the membrane-permeabilizing component of the Tat translocon for folded proteins. Here we review the known cases of non-lytic holin-mediated transport and then focus on the structural and functional comparison of TatA and TpeE, resulting in a mechanistic model for holin-mediated transport. This model is strongly supported by a so far not recognized naturally occurring holin-endolysin fusion protein.
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Affiliation(s)
- Thomas Brüser
- Institute of Microbiology, Leibniz Universität Hannover, Hannover, Germany
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7
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Irazoki O, Hernandez SB, Cava F. Peptidoglycan Muropeptides: Release, Perception, and Functions as Signaling Molecules. Front Microbiol 2019; 10:500. [PMID: 30984120 PMCID: PMC6448482 DOI: 10.3389/fmicb.2019.00500] [Citation(s) in RCA: 108] [Impact Index Per Article: 21.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2018] [Accepted: 02/27/2019] [Indexed: 12/12/2022] Open
Abstract
Peptidoglycan (PG) is an essential molecule for the survival of bacteria, and thus, its biosynthesis and remodeling have always been in the spotlight when it comes to the development of antibiotics. The peptidoglycan polymer provides a protective function in bacteria, but at the same time is continuously subjected to editing activities that in some cases lead to the release of peptidoglycan fragments (i.e., muropeptides) to the environment. Several soluble muropeptides have been reported to work as signaling molecules. In this review, we summarize the mechanisms involved in muropeptide release (PG breakdown and PG recycling) and describe the known PG-receptor proteins responsible for PG sensing. Furthermore, we overview the role of muropeptides as signaling molecules, focusing on the microbial responses and their functions in the host beyond their immunostimulatory activity.
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Affiliation(s)
| | | | - Felipe Cava
- Laboratory for Molecular Infection Medicine Sweden, Department of Molecular Biology, Umeå Centre for Microbial Research, Umeå University, Umeå, Sweden
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8
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Insights into Substrate Specificity of NlpC/P60 Cell Wall Hydrolases Containing Bacterial SH3 Domains. mBio 2015; 6:e02327-14. [PMID: 26374125 PMCID: PMC4600125 DOI: 10.1128/mbio.02327-14] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Bacterial SH3 (SH3b) domains are commonly fused with papain-like Nlp/P60 cell wall hydrolase domains. To understand how the modular architecture of SH3b and NlpC/P60 affects the activity of the catalytic domain, three putative NlpC/P60 cell wall hydrolases were biochemically and structurally characterized. These enzymes all have γ-d-Glu-A2pm (A2pm is diaminopimelic acid) cysteine amidase (or dl-endopeptidase) activities but with different substrate specificities. One enzyme is a cell wall lysin that cleaves peptidoglycan (PG), while the other two are cell wall recycling enzymes that only cleave stem peptides with an N-terminal l-Ala. Their crystal structures revealed a highly conserved structure consisting of two SH3b domains and a C-terminal NlpC/P60 catalytic domain, despite very low sequence identity. Interestingly, loops from the first SH3b domain dock into the ends of the active site groove of the catalytic domain, remodel the substrate binding site, and modulate substrate specificity. Two amino acid differences at the domain interface alter the substrate binding specificity in favor of stem peptides in recycling enzymes, whereas the SH3b domain may extend the peptidoglycan binding surface in the cell wall lysins. Remarkably, the cell wall lysin can be converted into a recycling enzyme with a single mutation. Peptidoglycan is a meshlike polymer that envelops the bacterial plasma membrane and bestows structural integrity. Cell wall lysins and recycling enzymes are part of a set of lytic enzymes that target covalent bonds connecting the amino acid and amino sugar building blocks of the PG network. These hydrolases are involved in processes such as cell growth and division, autolysis, invasion, and PG turnover and recycling. To avoid cleavage of unintended substrates, these enzymes have very selective substrate specificities. Our biochemical and structural analysis of three modular NlpC/P60 hydrolases, one lysin, and two recycling enzymes, show that they may have evolved from a common molecular architecture, where the substrate preference is modulated by local changes. These results also suggest that new pathways for recycling PG turnover products, such as tracheal cytotoxin, may have evolved in bacteria in the human gut microbiome that involve NlpC/P60 cell wall hydrolases.
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9
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Chan ACK, Blair KM, Liu Y, Frirdich E, Gaynor EC, Tanner ME, Salama NR, Murphy MEP. Helical shape of Helicobacter pylori requires an atypical glutamine as a zinc ligand in the carboxypeptidase Csd4. J Biol Chem 2014; 290:3622-38. [PMID: 25505267 DOI: 10.1074/jbc.m114.624734] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Peptidoglycan modifying carboxypeptidases (CPs) are important determinants of bacterial cell shape. Here, we report crystal structures of Csd4, a three-domain protein from the human gastric pathogen Helicobacter pylori. The catalytic zinc in Csd4 is coordinated by a rare His-Glu-Gln configuration that is conserved among most Csd4 homologs, which form a distinct subfamily of CPs. Substitution of the glutamine to histidine, the residue found in prototypical zinc carboxypeptidases, resulted in decreased enzyme activity and inhibition by phosphate. Expression of the histidine variant at the native locus in a H. pylori csd4 deletion strain did not restore the wild-type helical morphology. Biochemical assays show that Csd4 can cleave a tripeptide peptidoglycan substrate analog to release m-DAP. Structures of Csd4 with this substrate analog or product bound at the active site reveal determinants of peptidoglycan specificity and the mechanism to cleave an isopeptide bond to release m-DAP. Our data suggest that Csd4 is the archetype of a new CP subfamily with a domain scheme that differs from this large family of peptide-cleaving enzymes.
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Affiliation(s)
- Anson C K Chan
- From the Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
| | - Kris M Blair
- the Division of Human Biology, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109, the Program in Molecular and Cellular Biology, University of Washington, Seattle, Washington 98195, and
| | - Yanjie Liu
- the Department of Chemistry, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
| | - Emilisa Frirdich
- From the Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
| | - Erin C Gaynor
- From the Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
| | - Martin E Tanner
- the Department of Chemistry, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
| | - Nina R Salama
- the Division of Human Biology, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109, the Program in Molecular and Cellular Biology, University of Washington, Seattle, Washington 98195, and
| | - Michael E P Murphy
- From the Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada,
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Structure-guided functional characterization of DUF1460 reveals a highly specific NlpC/P60 amidase family. Structure 2014; 22:1799-1809. [PMID: 25465128 DOI: 10.1016/j.str.2014.09.018] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2014] [Revised: 09/22/2014] [Accepted: 09/24/2014] [Indexed: 01/01/2023]
Abstract
GlcNAc-1,6-anhydro-MurNAc-tetrapeptide is a major peptidoglycan degradation intermediate and a cytotoxin. It is generated by lytic transglycosylases and further degraded and recycled by various enzymes. We have identified and characterized a highly specific N-acetylmuramoyl-L-alanine amidase (AmiA) from Bacteroides uniformis, a member of the DUF1460 protein family, that hydrolyzes GlcNAc-1,6-anhydro-MurNAc-peptide into disaccharide and stem peptide. The high-resolution apo structure at 1.15 Å resolution shows that AmiA is related to NlpC/P60 γ-D-Glu-meso-diaminopimelic acid amidases and shares a common catalytic core and cysteine peptidase-like active site. AmiA has evolved structural adaptations that reconfigure the substrate recognition site. The preferred substrates for AmiA were predicted in silico based on structural and bioinformatics data, and subsequently were characterized experimentally. Further crystal structures of AmiA in complexes with GlcNAc-1,6-anhydro-MurNAc and GlcNAc have enabled us to elucidate substrate recognition and specificity. DUF1460 is highly conserved in structure and defines another amidase family.
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11
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Fortifying the wall: synthesis, regulation and degradation of bacterial peptidoglycan. Curr Opin Struct Biol 2013; 23:695-703. [DOI: 10.1016/j.sbi.2013.07.008] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2013] [Revised: 06/28/2013] [Accepted: 07/11/2013] [Indexed: 12/24/2022]
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12
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Shimada T, Yamazaki K, Ishihama A. Novel regulator PgrR for switch control of peptidoglycan recycling in Escherichia coli. Genes Cells 2013; 18:123-34. [PMID: 23301696 DOI: 10.1111/gtc.12026] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2012] [Accepted: 11/02/2012] [Indexed: 01/06/2023]
Abstract
Peptidoglycan (PG), also designated as murein, forms a skeletal mesh within the periplasm of bacterial membrane. PG is a metabolically stable cell architecture in Escherichia coli, but under as yet ill-defined conditions, a portion of PG is degraded, of which both amino sugar and peptide moieties are either recycled or used as self-generated nutrients for cell growth. At present, the control of PG degradation remains uncharacterized. Using the Genomic SELEX screening system, we identified an uncharacterized transcription factor YcjZ is a repressor of the expression of the initial step enzymes for PG peptide degradation. Under nutrient starvation, the genes encoding the enzymes for PG peptide degradation are derepressed so as to generate amino acids but are tightly repressed at high osmotic conditions so as to maintain the rigid membrane for withstanding the turgor. Taken together, we propose to rename YcjZ as PgrR (regulator of peptide glycan recycling).
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Affiliation(s)
- Tomohiro Shimada
- Department of Frontier Bioscience, Hosei University, Koganei, Tokyo, Japan
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