1
|
Jalil K, Tahara YO, Miyata M. Visualization of Bacillus subtilis spore structure and germination using quick-freeze deep-etch electron microscopy. Microscopy (Oxf) 2024:dfae023. [PMID: 38819330 DOI: 10.1093/jmicro/dfae023] [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: 03/06/2024] [Revised: 04/15/2024] [Accepted: 04/24/2024] [Indexed: 06/01/2024] Open
Abstract
Bacterial spores, known for their complex and resilient structures, have been the focus of visualization using various methodologies. In this study, we applied quick-freeze and replica electron microscopy techniques, allowing observation of Bacillus subtilis spores in high-contrast and three-dimensional detail. This method facilitated visualization of the spore structure with enhanced resolution and provided new insights into the spores and their germination processes. We identified and described five distinct structures: (i) hair-like structures on the spore surface, (ii) spike formation on the surface of lysozyme-treated spores, (iii) the fractured appearance of the spore cortex during germination, (iv) potential connections between small vesicles and the core membrane and (v) the evolving surface structure of nascent vegetative cells during germination.
Collapse
Affiliation(s)
- Kiran Jalil
- Graduate School of Science, Osaka Metropolitan University, Sumiyoshi-ku, Osaka 558-8585, Japan
| | - Yuhei O Tahara
- Graduate School of Science, Osaka Metropolitan University, Sumiyoshi-ku, Osaka 558-8585, Japan
- The OCU Advanced Research Institute for Natural Science and Technology (OCARINA), Osaka Metropolitan University, Sumiyoshi-ku, Osaka 558-8585, Japan
| | - Makoto Miyata
- Graduate School of Science, Osaka Metropolitan University, Sumiyoshi-ku, Osaka 558-8585, Japan
- The OCU Advanced Research Institute for Natural Science and Technology (OCARINA), Osaka Metropolitan University, Sumiyoshi-ku, Osaka 558-8585, Japan
| |
Collapse
|
2
|
Serrano M, Martins D, Henriques AO. Clostridioides difficile Sporulation. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2024; 1435:273-314. [PMID: 38175480 DOI: 10.1007/978-3-031-42108-2_13] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2024]
Abstract
Some members of the Firmicutes phylum, including many members of the human gut microbiota, are able to differentiate a dormant and highly resistant cell type, the endospore (hereinafter spore for simplicity). Spore-formers can colonize virtually any habitat and, because of their resistance to a wide variety of physical and chemical insults, spores can remain viable in the environment for long periods of time. In the anaerobic enteric pathogen Clostridioides difficile the aetiologic agent is the oxygen-resistant spore, while the toxins produced by actively growing cells are the main cause of the disease symptoms. Here, we review the regulatory circuits that govern entry into sporulation. We also cover the role of spores in the infectious cycle of C. difficile in relation to spore structure and function and the main control points along spore morphogenesis.
Collapse
Affiliation(s)
- Mónica Serrano
- Instituto de Tecnologia Química e Biológica António Xavier, Oeiras, Portugal.
| | - Diogo Martins
- Instituto de Tecnologia Química e Biológica António Xavier, Oeiras, Portugal
| | - Adriano O Henriques
- Instituto de Tecnologia Química e Biológica António Xavier, Oeiras, Portugal
| |
Collapse
|
3
|
Weaver A, Taguchi A, Dörr T. Masters of Misdirection: Peptidoglycan Glycosidases in Bacterial Growth. J Bacteriol 2023; 205:e0042822. [PMID: 36757204 PMCID: PMC10029718 DOI: 10.1128/jb.00428-22] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/10/2023] Open
Abstract
The dynamic composition of the peptidoglycan cell wall has been the subject of intense research for decades, yet how bacteria coordinate the synthesis of new peptidoglycan with the turnover and remodeling of existing peptidoglycan remains elusive. Diversity and redundancy within peptidoglycan synthases and peptidoglycan autolysins, enzymes that degrade peptidoglycan, have often made it challenging to assign physiological roles to individual enzymes and determine how those activities are regulated. For these reasons, peptidoglycan glycosidases, which cleave within the glycan strands of peptidoglycan, have proven veritable masters of misdirection over the years. Unlike many of the broadly conserved peptidoglycan synthetic complexes, diverse bacteria can employ unrelated glycosidases to achieve the same physiological outcome. Additionally, although the mechanisms of action for many individual enzymes have been characterized, apparent conserved homologs in other organisms can exhibit an entirely different biochemistry. This flexibility has been recently demonstrated in the context of three functions critical to vegetative growth: (i) release of newly synthesized peptidoglycan strands from their membrane anchors, (ii) processing of peptidoglycan turned over during cell wall expansion, and (iii) removal of peptidoglycan fragments that interfere with daughter cell separation during cell division. Finally, the regulation of glycosidase activity during these cell processes may be a cumulation of many factors, including protein-protein interactions, intrinsic substrate preferences, substrate availability, and subcellular localization. Understanding the true scope of peptidoglycan glycosidase activity will require the exploration of enzymes from diverse organisms with equally diverse growth and division strategies.
Collapse
Affiliation(s)
- Anna Weaver
- Department of Microbiology, Blavatnik Institute, Harvard Medical School, Boston, Massachusetts, USA
| | - Atsushi Taguchi
- SANKEN (The Institute of Scientific and Industrial Research), Osaka University, Ibaraki, Osaka, Japan
| | - Tobias Dörr
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, New York, USA
- Department of Microbiology, Cornell University, Ithaca, New York, USA
- Cornell Institute of Host-Microbe Interactions and Disease, Cornell University, Ithaca, New York, USA
| |
Collapse
|
4
|
Mechanisms and Applications of Bacterial Sporulation and Germination in the Intestine. Int J Mol Sci 2022; 23:ijms23063405. [PMID: 35328823 PMCID: PMC8953710 DOI: 10.3390/ijms23063405] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Revised: 03/15/2022] [Accepted: 03/18/2022] [Indexed: 02/04/2023] Open
Abstract
Recent studies have suggested a major role for endospore forming bacteria within the gut microbiota, not only as pathogens but also as commensal and beneficial members contributing to gut homeostasis. In this review the sporulation processes, spore properties, and germination processes will be explained within the scope of the human gut. Within the gut, spore-forming bacteria are known to interact with the host’s immune system, both in vegetative cell and spore form. Together with the resistant nature of the spore, these characteristics offer potential for spores’ use as delivery vehicles for therapeutics. In the last part of the review, the therapeutic potential of spores as probiotics, vaccine vehicles, and drug delivery systems will be discussed.
Collapse
|
5
|
Moore JH, Salahi A, Honrado C, Warburton C, Warren CA, Swami NS. Quantifying bacterial spore germination by single-cell impedance cytometry for assessment of host microbiota susceptibility to Clostridioides difficile infection. Biosens Bioelectron 2020; 166:112440. [PMID: 32745926 DOI: 10.1016/j.bios.2020.112440] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Revised: 06/18/2020] [Accepted: 07/08/2020] [Indexed: 12/11/2022]
Abstract
The germination of ingested spores is often a necessary first step required for enabling bacterial outgrowth and host colonization, as in the case of Clostridioides difficile (C. difficile) infection. Spore germination rate in the colon depends on microbiota composition and its level of disruption by antibiotic treatment since secretions by commensal bacteria modulate primary to secondary bile salt levels to control germination. Assessment of C. difficile spore germination typically requires measurement of colony-forming units, which is labor intensive and takes at least 24 h to perform but is regularly required due to the high recurrence rates of nosocomial antibiotic-associated diarrhea. We present a rapid method to assess spore germination by using high throughput single-cell impedance cytometry (>300 events/s) to quantify live bacterial cells, by gating for their characteristic electrophysiology versus spores, so that germination can be assessed after just 4 h of culture at a detection limit of ~100 live cells per 50 μL sample. To detect the phenotype of germinated C. difficile bacteria, we utilize its characteristically higher net conductivity versus that of spore aggregates and non-viable C. difficile forms, which causes a distinctive high-frequency (10 MHz) impedance phase dispersion within moderately conductive media (0.8 S/m). In this manner, we can detect significant differences in spore germination rates within just 4 h, with increasing primary bile salt levels in vitro and using ex vivo microbiota samples from an antibiotic-treated mouse model to assess susceptibility to C. difficile infection. We envision a rapid diagnostic tool for assessing host microbiota susceptibility to bacterial colonization after key antibiotic treatments.
Collapse
Affiliation(s)
- John H Moore
- Electrical & Computer Engineering, University of Virginia, Charlottesville, VA, 22904, USA
| | - Armita Salahi
- Electrical & Computer Engineering, University of Virginia, Charlottesville, VA, 22904, USA
| | - Carlos Honrado
- Electrical & Computer Engineering, University of Virginia, Charlottesville, VA, 22904, USA
| | | | - Cirle A Warren
- Infectious Diseases, School of Medicine, University of Virginia, VA, 22904, USA
| | - Nathan S Swami
- Electrical & Computer Engineering, University of Virginia, Charlottesville, VA, 22904, USA.
| |
Collapse
|
6
|
Amon JD, Yadav AK, Ramirez-Guadiana FH, Meeske AJ, Cava F, Rudner DZ. SwsB and SafA Are Required for CwlJ-Dependent Spore Germination in Bacillus subtilis. J Bacteriol 2020; 202:e00668-19. [PMID: 31871031 PMCID: PMC7043669 DOI: 10.1128/jb.00668-19] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Accepted: 12/13/2019] [Indexed: 02/07/2023] Open
Abstract
When Bacillus subtilis spores detect nutrients, they exit dormancy through the processes of germination and outgrowth. A key step in germination is the activation of two functionally redundant cell wall hydrolases (SleB and CwlJ) that degrade the specialized cortex peptidoglycan that surrounds the spore. How these enzymes are regulated remains poorly understood. To identify additional factors that affect their activity, we used transposon sequencing to screen for synthetic germination defects in spores lacking SleB or CwlJ. Other than the previously characterized protein YpeB, no additional factors were found to be specifically required for SleB activity. In contrast, our screen identified SafA and YlxY (renamed SwsB) in addition to the known factors GerQ and CotE as proteins required for CwlJ function. SafA is a member of the spore's proteinaceous coat and we show that, like GerQ and CotE, it is required for accumulation and retention of CwlJ in the dormant spore. SwsB is broadly conserved among spore formers, and we show that it is required for CwlJ to efficiently degrade the cortex during germination. Intriguingly, SwsB resembles polysaccharide deacetylases, and its putative catalytic residues are required for its role in germination. However, we find no chemical signature of its activity on the spore cortex or in vitro While the precise, mechanistic role of SwsB remains unknown, we explore and discuss potential activities.IMPORTANCE Spore formation in Bacillus subtilis has been studied for over half a century, and virtually every step in this developmental process has been characterized in molecular detail. In contrast, how spores exit dormancy remains less well understood. A key step in germination is the degradation of the specialized cell wall surrounding the spore called the cortex. Two enzymes (SleB and CwlJ) specifically target this protective layer, but how they are regulated and whether additional factors promote their activity are unknown. Here, we identified the coat protein SafA and a conserved but uncharacterized protein YlxY as additional factors required for CwlJ-dependent degradation of the cortex. Our analysis provides a more complete picture of this essential step in the exit from dormancy.
Collapse
Affiliation(s)
- Jeremy D Amon
- Department of Microbiology, Harvard Medical School, Boston, Massachusetts, USA
| | - Akhilesh K Yadav
- Laboratory for Molecular Infection Medicine, Department of Molecular Biology, Umeå University, Umeå, Sweden
- Analytical Chemistry Division, CSIR-Indian Institute of Toxicology Research, Lucknow, India
| | | | - Alexander J Meeske
- Department of Microbiology, Harvard Medical School, Boston, Massachusetts, USA
| | - Felipe Cava
- Laboratory for Molecular Infection Medicine, Department of Molecular Biology, Umeå University, Umeå, Sweden
| | - David Z Rudner
- Department of Microbiology, Harvard Medical School, Boston, Massachusetts, USA
| |
Collapse
|
7
|
Aspholm ME, Kollerud KK, Høgberg Hansen HC, Granum PE, Christie G, Lindbäck T. Biochemical and mutational analysis of spore cortex-lytic enzymes in the food spoiler Bacillus licheniformis. Food Microbiol 2019; 84:103259. [PMID: 31421778 DOI: 10.1016/j.fm.2019.103259] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Revised: 07/01/2019] [Accepted: 07/03/2019] [Indexed: 12/11/2022]
Abstract
Bacillus licheniformis is frequently associated with food spoilage due to its ability to form highly resistant endospores. The present study reveals that B. licheniformis spore peptidoglycan shares a similar structure to spores of other species of Bacillus. Two enzymatic activities associated with depolymerisation of the cortical peptidoglycan, which represents a crucial step in spore germination, were detected by muropeptide analysis. These include lytic transglycosylase and N-acetylglucosaminidase activity, with non-lytic epimerase activity also being detected. The role of various putative cortex-lytic enzymes that account for the aforementioned activity was investigated by mutational analysis. These analyses indicate that SleB is the major lysin involved in cortex depolymerisation in B. licheniformis spores, with CwlJ and SleL having lesser roles. Collectively, the results of this work indicate that B. licheniformis spores employ a similar approach for cortical depolymerisation during germination as spores of other Bacillus species.
Collapse
Affiliation(s)
- Marina E Aspholm
- Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Pb 369 Sentrum, 0102, Oslo, Norway
| | - Kristian K Kollerud
- Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Pb 369 Sentrum, 0102, Oslo, Norway
| | - Helge C Høgberg Hansen
- Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Pb 369 Sentrum, 0102, Oslo, Norway
| | - Per Einar Granum
- Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Pb 369 Sentrum, 0102, Oslo, Norway
| | - Graham Christie
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, United Kingdom
| | - Toril Lindbäck
- Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Pb 369 Sentrum, 0102, Oslo, Norway.
| |
Collapse
|
8
|
Diaz OR, Sayer CV, Popham DL, Shen A. Clostridium difficile Lipoprotein GerS Is Required for Cortex Modification and Thus Spore Germination. mSphere 2018; 3:e00205-18. [PMID: 29950380 PMCID: PMC6021603 DOI: 10.1128/msphere.00205-18] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Accepted: 04/22/2018] [Indexed: 02/04/2023] Open
Abstract
Clostridium difficile, also known as Clostridioides difficile, is a Gram-positive, spore-forming bacterium that is a leading cause of antibiotic-associated diarrhea. C. difficile infections begin when its metabolically dormant spores germinate to form toxin-producing vegetative cells. Successful spore germination depends on the degradation of the cortex, a thick layer of modified peptidoglycan that maintains dormancy. Cortex degradation is mediated by the SleC cortex lytic enzyme, which is thought to recognize the cortex-specific modification muramic-δ-lactam. C. difficile cortex degradation also depends on the Peptostreptococcaceae-specific lipoprotein GerS for unknown reasons. In this study, we tested whether GerS regulates production of muramic-δ-lactam and thus controls the ability of SleC to recognize its cortex substrate. By comparing the muropeptide profiles of ΔgerS spores to those of spores lacking either CwlD or PdaA, both of which mediate cortex modification in Bacillus subtilis, we determined that C. difficile GerS, CwlD, and PdaA are all required to generate muramic-δ-lactam. Both GerS and CwlD were needed to cleave the peptide side chains from N-acetylmuramic acid, suggesting that these two factors act in concert. Consistent with this hypothesis, biochemical analyses revealed that GerS and CwlD directly interact and that CwlD modulates GerS incorporation into mature spores. Since ΔgerS, ΔcwlD, and ΔpdaA spores exhibited equivalent germination defects, our results indicate that C. difficile spore germination depends on cortex-specific modifications, reveal GerS as a novel regulator of these processes, and highlight additional differences in the regulation of spore germination in C. difficile relative to B. subtilis and other spore-forming organisms.IMPORTANCE The Gram-positive, spore-forming bacterium Clostridium difficile is a leading cause of antibiotic-associated diarrhea. Because C. difficile is an obligate anaerobe, its aerotolerant spores are essential for transmitting disease, and their germination into toxin-producing cells is necessary for causing disease. Spore germination requires the removal of the cortex, a thick layer of modified peptidoglycan that maintains spore dormancy. Cortex degradation is mediated by the SleC hydrolase, which is thought to recognize cortex-specific modifications. Cortex degradation also requires the GerS lipoprotein for unknown reasons. In our study, we tested whether GerS is required to generate cortex-specific modifications by comparing the cortex composition of ΔgerS spores to the cortex composition of spores lacking two putative cortex-modifying enzymes, CwlD and PdaA. These analyses revealed that GerS, CwlD, and PdaA are all required to generate cortex-specific modifications. Since loss of these modifications in ΔgerS, ΔcwlD, and ΔpdaA mutants resulted in spore germination and heat resistance defects, the SleC cortex lytic enzyme depends on cortex-specific modifications to efficiently degrade this protective layer. Our results further indicate that GerS and CwlD are mutually required for removing peptide chains from spore peptidoglycan and revealed a novel interaction between these proteins. Thus, our findings provide new mechanistic insight into C. difficile spore germination.
Collapse
Affiliation(s)
- Oscar R Diaz
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts, USA
- NIH Postbaccalaureate Research Education Program (PREP), Tufts University School of Medicine, Boston, Massachusetts, USA
| | - Cameron V Sayer
- Department of Biological Sciences, Virginia Tech, Blacksburg, Virginia, USA
| | - David L Popham
- Department of Biological Sciences, Virginia Tech, Blacksburg, Virginia, USA
| | - Aimee Shen
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts, USA
| |
Collapse
|
9
|
Desvaux M, Candela T, Serror P. Surfaceome and Proteosurfaceome in Parietal Monoderm Bacteria: Focus on Protein Cell-Surface Display. Front Microbiol 2018; 9:100. [PMID: 29491848 PMCID: PMC5817068 DOI: 10.3389/fmicb.2018.00100] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Accepted: 01/16/2018] [Indexed: 12/12/2022] Open
Abstract
The cell envelope of parietal monoderm bacteria (archetypal Gram-positive bacteria) is formed of a cytoplasmic membrane (CM) and a cell wall (CW). While the CM is composed of phospholipids, the CW is composed at least of peptidoglycan (PG) covalently linked to other biopolymers, such as teichoic acids, polysaccharides, and/or polyglutamate. Considering the CW is a porous structure with low selective permeability contrary to the CM, the bacterial cell surface hugs the molecular figure of the CW components as a well of the external side of the CM. While the surfaceome corresponds to the totality of the molecules found at the bacterial cell surface, the proteinaceous complement of the surfaceome is the proteosurfaceome. Once translocated across the CM, secreted proteins can either be released in the extracellular milieu or exposed at the cell surface by associating to the CM or the CW. Following the gene ontology (GO) for cellular components, cell-surface proteins at the CM can either be integral (GO: 0031226), i.e., the integral membrane proteins, or anchored to the membrane (GO: 0046658), i.e., the lipoproteins. At the CW (GO: 0009275), cell-surface proteins can be covalently bound, i.e., the LPXTG-proteins, or bound through weak interactions to the PG or wall polysaccharides, i.e., the cell wall binding proteins. Besides monopolypeptides, some proteins can associate to each other to form supramolecular protein structures of high molecular weight, namely the S-layer, pili, flagella, and cellulosomes. After reviewing the cell envelope components and the different molecular mechanisms involved in protein attachment to the cell envelope, perspectives in investigating the proteosurfaceome in parietal monoderm bacteria are further discussed.
Collapse
Affiliation(s)
- Mickaël Desvaux
- Université Clermont Auvergne, INRA, UMR454 MEDiS, Clermont-Ferrand, France
| | - Thomas Candela
- EA4043 Unité Bactéries Pathogènes et Santé, Châtenay-Malabry, France
| | - Pascale Serror
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, France
| |
Collapse
|
10
|
Abstract
Bacterial endospores possess multiple integument layers, one of which is the cortex peptidoglycan wall. The cortex is essential for the maintenance of spore core dehydration and dormancy and contains structural modifications that differentiate it from vegetative cell peptidoglycan and determine its fate during spore germination. Following the engulfment stage of sporulation, the cortex is synthesized within the intermembrane space surrounding the forespore. Proteins responsible for cortex synthesis are produced in both the forespore and mother cell compartments. While some of these proteins also contribute to vegetative cell wall synthesis, others are sporulation specific. In order for the bacterial endospore to germinate and resume metabolism, the cortex peptidoglycan must first be degraded through the action of germination-specific lytic enzymes. These enzymes are present, yet inactive, in the dormant spore and recognize the muramic-δ-lactam modification present in the cortex. Germination-specific lytic enzymes across Bacillaceae and Clostridiaceae share this specificity determinant, which ensures that the spore cortex is hydrolyzed while the vegetative cell wall remains unharmed. Bacillus species tend to possess two redundant enzymes, SleB and CwlJ, capable of sufficient cortex degradation, while the clostridia have only one, SleC. Additional enzymes are often present that cannot initiate the cortex degradation process, but which can increase the rate of release of small fragments into the medium. Between the two families, the enzymes also differ in the enzymatic activities they possess and the mechanisms acting to restrict their activation until germination has been initiated.
Collapse
|
11
|
Omardien S, Brul S, Zaat SAJ. Antimicrobial Activity of Cationic Antimicrobial Peptides against Gram-Positives: Current Progress Made in Understanding the Mode of Action and the Response of Bacteria. Front Cell Dev Biol 2016; 4:111. [PMID: 27790614 PMCID: PMC5063857 DOI: 10.3389/fcell.2016.00111] [Citation(s) in RCA: 115] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2016] [Accepted: 09/21/2016] [Indexed: 01/11/2023] Open
Abstract
Antimicrobial peptides (AMPs) have been proposed as a novel class of antimicrobials that could aid the fight against antibiotic resistant bacteria. The mode of action of AMPs as acting on the bacterial cytoplasmic membrane has often been presented as an enigma and there are doubts whether the membrane is the sole target of AMPs. Progress has been made in clarifying the possible targets of these peptides, which is reported in this review with as focus gram-positive vegetative cells and spores. Numerical estimates are discussed to evaluate the possibility that targets, other than the membrane, could play a role in susceptibility to AMPs. Concerns about possible resistance that bacteria might develop to AMPs are addressed. Proteomics, transcriptomics, and other molecular techniques are reviewed in the context of explaining the response of bacteria to the presence of AMPs and to predict what resistance strategies might be. Emergent mechanisms are cell envelope stress responses as well as enzymes able to degrade and/or specifically bind (and thus inactivate) AMPs. Further studies are needed to address the broadness of the AMP resistance and stress responses observed.
Collapse
Affiliation(s)
- Soraya Omardien
- Department of Molecular Biology and Microbial Food Safety, Swammerdam Institute for Life Sciences, University of Amsterdam Amsterdam, Netherlands
| | - Stanley Brul
- Department of Molecular Biology and Microbial Food Safety, Swammerdam Institute for Life Sciences, University of Amsterdam Amsterdam, Netherlands
| | - Sebastian A J Zaat
- Department of Medical Microbiology, Center for Infection and Immunity Amsterdam, Academic Medical Center, University of Amsterdam Amsterdam, Netherlands
| |
Collapse
|
12
|
Üstok FI, Chirgadze DY, Christie G. Structural and functional analysis of SleL, a peptidoglycan lysin involved in germination of B
acillus
spores. Proteins 2015; 83:1787-99. [DOI: 10.1002/prot.24861] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2015] [Revised: 06/19/2015] [Accepted: 07/02/2015] [Indexed: 11/11/2022]
Affiliation(s)
- Fatma Işık Üstok
- Department of Chemical Engineering and Biotechnology; Institute of Biotechnology, University of Cambridge; Cambridge United Kingdom
- Department of Haematology, Division of Structural Medicine and Thrombosis Research Unit, Cambridge Institute for Medical Research, University of Cambridge; Cambridge United Kingdom
| | - Dimitri Y. Chirgadze
- Department of Biochemistry, Crystallography and Biocomputing Unit; University of Cambridge; Cambridge United Kingdom
| | - Graham Christie
- Department of Chemical Engineering and Biotechnology; Institute of Biotechnology, University of Cambridge; Cambridge United Kingdom
| |
Collapse
|
13
|
Levefaudes M, Patin D, de Sousa-d'Auria C, Chami M, Blanot D, Hervé M, Arthur M, Houssin C, Mengin-Lecreulx D. Diaminopimelic Acid Amidation in Corynebacteriales: NEW INSIGHTS INTO THE ROLE OF LtsA IN PEPTIDOGLYCAN MODIFICATION. J Biol Chem 2015; 290:13079-94. [PMID: 25847251 DOI: 10.1074/jbc.m115.642843] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Indexed: 11/06/2022] Open
Abstract
A gene named ltsA was earlier identified in Rhodococcus and Corynebacterium species while screening for mutations leading to increased cell susceptibility to lysozyme. The encoded protein belonged to a huge family of glutamine amidotransferases whose members catalyze amide nitrogen transfer from glutamine to various specific acceptor substrates. We here describe detailed physiological and biochemical investigations demonstrating the specific role of LtsA protein from Corynebacterium glutamicum (LtsACg) in the modification by amidation of cell wall peptidoglycan diaminopimelic acid (DAP) residues. A morphologically altered but viable ΔltsA mutant was generated, which displays a high susceptibility to lysozyme and β-lactam antibiotics. Analysis of its peptidoglycan structure revealed a total loss of DAP amidation, a modification that was found in 80% of DAP residues in the wild-type polymer. The cell peptidoglycan content and cross-linking were otherwise not modified in the mutant. Heterologous expression of LtsACg in Escherichia coli yielded a massive and toxic incorporation of amidated DAP into the peptidoglycan that ultimately led to cell lysis. In vitro assays confirmed the amidotransferase activity of LtsACg and showed that this enzyme used the peptidoglycan lipid intermediates I and II but not, or only marginally, the UDP-MurNAc pentapeptide nucleotide precursor as acceptor substrates. As is generally the case for glutamine amidotransferases, either glutamine or NH4(+) could serve as the donor substrate for LtsACg. The enzyme did not amidate tripeptide- and tetrapeptide-truncated versions of lipid I, indicating a strict specificity for a pentapeptide chain length.
Collapse
Affiliation(s)
- Marjorie Levefaudes
- From the Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris Sud, F-91198 Gif-sur-Yvette, France
| | - Delphine Patin
- From the Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris Sud, F-91198 Gif-sur-Yvette, France
| | - Célia de Sousa-d'Auria
- From the Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris Sud, F-91198 Gif-sur-Yvette, France
| | - Mohamed Chami
- the Center for Cellular Imaging and NanoAnalytics (C-CINA), Biozentrum, University of Basel, CH-4058 Basel, Switzerland
| | - Didier Blanot
- From the Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris Sud, F-91198 Gif-sur-Yvette, France
| | - Mireille Hervé
- From the Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris Sud, F-91198 Gif-sur-Yvette, France
| | - Michel Arthur
- INSERM, UMR S1138, Centre de Recherche des Cordeliers, Equipe 12, F-75006 Paris, France, the Sorbonne Universités, UPMC Université Paris 06, UMR S1138, Centre de Recherche des Cordeliers, F-75006 Paris, France, and the Université Paris-Descartes, Sorbonne Paris Cité, UMR S1138, Centre de Recherche des Cordeliers, F-75006, Paris, France
| | - Christine Houssin
- From the Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris Sud, F-91198 Gif-sur-Yvette, France,
| | - Dominique Mengin-Lecreulx
- From the Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris Sud, F-91198 Gif-sur-Yvette, France,
| |
Collapse
|
14
|
Wu X, Grover N, Paskaleva EE, Mundra RV, Page MA, Kane RS, Dordick JS. Characterization of the activity of the spore cortex lytic enzyme CwlJ1. Biotechnol Bioeng 2015; 112:1365-75. [DOI: 10.1002/bit.25565] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2014] [Revised: 01/27/2015] [Accepted: 02/02/2015] [Indexed: 11/09/2022]
Affiliation(s)
- Xia Wu
- Howard P. Isermann Department of Chemical and Biological Engineering; Rensselaer Polytechnic Institute; 110 8th Street, Troy New York 12180
- Center for Biotechnology and Interdisciplinary Studies; Rensselaer Polytechnic Institute; Troy New York 12180
| | - Navdeep Grover
- Center for Biotechnology and Interdisciplinary Studies; Rensselaer Polytechnic Institute; Troy New York 12180
| | - Elena E. Paskaleva
- Center for Biotechnology and Interdisciplinary Studies; Rensselaer Polytechnic Institute; Troy New York 12180
| | - Ruchir V. Mundra
- Howard P. Isermann Department of Chemical and Biological Engineering; Rensselaer Polytechnic Institute; 110 8th Street, Troy New York 12180
- Center for Biotechnology and Interdisciplinary Studies; Rensselaer Polytechnic Institute; Troy New York 12180
| | - Martin A. Page
- U.S. Army Engineer Research and Development Center; Construction Engineering Research Laboratory; Champaign Illinois
| | - Ravi S. Kane
- Howard P. Isermann Department of Chemical and Biological Engineering; Rensselaer Polytechnic Institute; 110 8th Street, Troy New York 12180
- Center for Biotechnology and Interdisciplinary Studies; Rensselaer Polytechnic Institute; Troy New York 12180
| | - Jonathan S. Dordick
- Howard P. Isermann Department of Chemical and Biological Engineering; Rensselaer Polytechnic Institute; 110 8th Street, Troy New York 12180
- Center for Biotechnology and Interdisciplinary Studies; Rensselaer Polytechnic Institute; Troy New York 12180
- Department of Materials Science and Engineering; Department of Biology; Department of Biomedical Engineering; Rensselaer Polytechnic Institute; Troy New York 12180
| |
Collapse
|
15
|
Popham DL. Visualizing the production and arrangement of peptidoglycan in Gram-positive cells. Mol Microbiol 2013; 88:645-9. [PMID: 23551458 DOI: 10.1111/mmi.12212] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/19/2013] [Indexed: 11/26/2022]
Abstract
Decades of study have revealed the fine chemical structure of the bacterial peptidoglycan cell wall, but the arrangement of the peptidoglycan strands within the wall has been challenging to define. The application of electron cryotomography (ECT) and new methods for fluorescent labelling of peptidoglycan are allowing new insights into wall structure and synthesis. Two articles in this issue examine peptidoglycan structures in the model Gram-positive species Bacillus subtilis. Beeby et al. combined visualization of peptidoglycan using ECT with molecular modelling of three proposed arrangements of peptidoglycan strands to identify the model most consistent with their data. They argue convincingly for a Gram-positive wall containing multiple layers of peptidoglycan strands arranged circumferentially around the long axis of the rod-shaped cell, an arrangement similar to the single layer of peptidoglycan in similarly shaped Gram-negative cells. Tocheva et al. examined sporulating cells using ECT and fluorescence microscopy to demonstrate the continuous production of a thin layer of peptidoglycan around the developing spore as it is engulfed by the membrane of the adjacent mother cell. The presence of this peptidoglycan in the intermembrane space allows the refinement of a model for engulfment, which has been known to include peptidoglycan synthetic and lytic functions.
Collapse
Affiliation(s)
- David L Popham
- Department of Biological Sciences - MC0910, Virginia Tech, Blacksburg, VA 24061, USA.
| |
Collapse
|
16
|
Tocheva EI, López-Garrido J, Hughes HV, Fredlund J, Kuru E, Vannieuwenhze MS, Brun YV, Pogliano K, Jensen GJ. Peptidoglycan transformations during Bacillus subtilis sporulation. Mol Microbiol 2013; 88:673-86. [PMID: 23531131 DOI: 10.1111/mmi.12201] [Citation(s) in RCA: 81] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/04/2013] [Indexed: 11/28/2022]
Abstract
While vegetative Bacillus subtilis cells and mature spores are both surrounded by a thick layer of peptidoglycan (PG, a polymer of glycan strands cross-linked by peptide bridges), it has remained unclear whether PG surrounds prespores during engulfment. To clarify this issue, we generated a slender ΔponA mutant that enabled high-resolution electron cryotomographic imaging. Three-dimensional reconstructions of whole cells in near-native states revealed a thin PG-like layer extending from the lateral cell wall around the prespore throughout engulfment. Cryotomography of purified sacculi and fluorescent labelling of PG in live cells confirmed that PG surrounds the prespore. The presence of PG throughout engulfment suggests new roles for PG in sporulation, including a new model for how PG synthesis might drive engulfment, and obviates the need to synthesize a PG layer de novo during cortex formation. In addition, it reveals that B. subtilis can synthesize thin, Gram-negative-like PG layers as well as its thick, archetypal Gram-positive cell wall. The continuous transformations from thick to thin and back to thick during sporulation suggest that both forms of PG have the same basic architecture (circumferential). Endopeptidase activity may be the main switch that governs whether a thin or a thick PG layer is assembled.
Collapse
Affiliation(s)
- Elitza I Tocheva
- Division of Biology, California Institute of Technology, 1200 E California Blvd, Pasadena, CA 91125, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
17
|
Ronholm J, Wang L, Hayashi I, Sugai M, Zhang Z, Cao X, Lin M. The Listeria monocytogenes serotype 4b autolysin IspC has N-acetylglucosaminidase activity. Glycobiology 2012; 22:1311-20. [DOI: 10.1093/glycob/cws100] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
|
18
|
Leggett MJ, McDonnell G, Denyer SP, Setlow P, Maillard JY. Bacterial spore structures and their protective role in biocide resistance. J Appl Microbiol 2012; 113:485-98. [PMID: 22574673 DOI: 10.1111/j.1365-2672.2012.05336.x] [Citation(s) in RCA: 151] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The structure and chemical composition of bacterial spores differ considerably from those of vegetative cells. These differences largely account for the unique resistance properties of the spore to environmental stresses, including disinfectants and sterilants, resulting in the emergence of spore-forming bacteria such as Clostridium difficile as major hospital pathogens. Although there has been considerable work investigating the mechanisms of action of many sporicidal biocides against Bacillus subtilis spores, there is far less information available for other species and particularly for various Clostridia. This paucity of information represents a major gap in our knowledge given the importance of Clostridia as human pathogens. This review considers the main spore structures, highlighting their relevance to spore resistance properties and detailing their chemical composition, with a particular emphasis on the differences between various spore formers. Such information will be vital for the rational design and development of novel sporicidal chemistries with enhanced activity in the future.
Collapse
Affiliation(s)
- M J Leggett
- Cardiff School of Pharmacy and Pharmaceutical Sciences, Cardiff University, Cardiff, UK
| | | | | | | | | |
Collapse
|
19
|
Forster BM, Marquis H. Protein transport across the cell wall of monoderm Gram-positive bacteria. Mol Microbiol 2012; 84:405-13. [PMID: 22471582 DOI: 10.1111/j.1365-2958.2012.08040.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
In monoderm (single-membrane) Gram-positive bacteria, the majority of secreted proteins are first translocated across the cytoplasmic membrane into the inner wall zone. For a subset of these proteins, final destination is within the cell envelope as either membrane-anchored or cell wall-anchored proteins, whereas another subset of proteins is destined to be transported across the cell wall into the extracellular milieu. Although the cell wall is a porous structure, there is evidence that, for some proteins, transport is a regulated process. This review aims at describing what is known about the mechanisms that regulate the transport of proteins across the cell wall of monoderm Gram-positive bacteria.
Collapse
Affiliation(s)
- Brian M Forster
- Department of Microbiology and Immunology, Cornell University, Ithaca, NY 14853, USA
| | | |
Collapse
|
20
|
Lambert EA, Sherry N, Popham DL. In vitro and in vivo analyses of the Bacillus anthracis spore cortex lytic protein SleL. MICROBIOLOGY-SGM 2012; 158:1359-1368. [PMID: 22343356 DOI: 10.1099/mic.0.056630-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
The bacterial endospore is the most resilient biological structure known. Multiple protective integument layers shield the spore core and promote spore dehydration and dormancy. Dormancy is broken when a spore germinates and becomes a metabolically active vegetative cell. Germination requires the breakdown of a modified layer of peptidoglycan (PG) known as the spore cortex. This study reports in vitro and in vivo analyses of the Bacillus anthracis SleL protein. SleL is a spore cortex lytic enzyme composed of three conserved domains: two N-terminal LysM domains and a C-terminal glycosyl hydrolase family 18 domain. Derivatives of SleL containing both, one or no LysM domains were purified and characterized. SleL is incapable of digesting intact cortical PG of either decoated spores or purified spore sacculi. However, SleL derivatives can hydrolyse fragmented PG substrates containing muramic-δ-lactam recognition determinants. The muropeptides that result from SleL hydrolysis are the products of N-acetylglucosaminidase activity. These muropeptide products are small and readily released from the cortex matrix. Loss of the LysM domain(s) decreases both PG binding and hydrolysis activity but these domains do not appear to determine specificity for muramic-δ-lactam. When the SleL derivatives are expressed in vivo, those proteins lacking one or both LysM domains do not associate with the spore. Instead, these proteins remain in the mother cell and are apparently degraded. SleL with both LysM domains localizes to the coat or cortex of the endospore. The information revealed by elucidating the role of SleL and its domains in B. anthracis sporulation and germination is important in designing new spore decontamination methods. By exploiting germination-specific lytic enzymes, eradication techniques may be greatly simplified.
Collapse
Affiliation(s)
- Emily A Lambert
- Department of Biological Sciences, Virginia Tech., Life Sciences I-MC0910, Blacksburg, VA 24061, USA
| | - Nora Sherry
- Department of Biological Sciences, Virginia Tech., Life Sciences I-MC0910, Blacksburg, VA 24061, USA
| | - David L Popham
- Department of Biological Sciences, Virginia Tech., Life Sciences I-MC0910, Blacksburg, VA 24061, USA
| |
Collapse
|
21
|
Fulmer PA, Wynne JH. Coatings capable of germinating and neutralizing Bacillus anthracis endospores. ACS APPLIED MATERIALS & INTERFACES 2012; 4:738-743. [PMID: 22211260 DOI: 10.1021/am201362u] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Endospores are formed by various bacterial families, including Bacillus and Clostridium, in response to environmental stresses as a means to survive conditions inhospitable to vegetative growth. Although metabolically inert, the endospore must interact with its environment to determine an optimal time to return to a vegetative state, a process known as germination. Germination has been shown to occur in response to a variety of chemical stimuli from specific nutrient germinants including amino acids, sugars and nucleosides. This process is known to be mediated primarily by the GerA family of spore-specific receptor proteins which initiates a signal transduction cascade that results in a return of oxidative metabolism in response to germinant receptor interactions. Herein, we report the development of a novel coating system capable of germinating B. anthracis endospores, followed by rapid killing of the vegetative bacteria by a novel incorporated amphiphilic biocide. The most effective formulation tested exhibited an ability to germinate and kill B. anthracis endospores and vegetative bacteria, respectively. The formulation reported resulted in a 90% reduction in as little as 5 min, and a 6 log reduction by 45 min.
Collapse
Affiliation(s)
- Preston A Fulmer
- Chemistry Division, Code 6100, Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, DC 20375, United States
| | | |
Collapse
|
22
|
In vitro studies of peptidoglycan binding and hydrolysis by the Bacillus anthracis germination-specific lytic enzyme SleB. J Bacteriol 2010; 193:125-31. [PMID: 20971910 DOI: 10.1128/jb.00869-10] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The Bacillus anthracis endospore loses resistance properties during germination when its cortex peptidoglycan is degraded by germination-specific lytic enzymes (GSLEs). Although this event normally employs several GSLEs for complete cortex removal, the SleB protein alone can facilitate enough cortex hydrolysis to produce vulnerable spores. As a means to better understand its enzymatic function, SleB was overexpressed, purified, and tested in vitro for depolymerization of cortex by measurement of optical density loss and the solubilization of substrate. Its ability to bind peptidoglycan was also investigated. SleB functions independently as a lytic transglycosylase on both intact and fragmented cortex. Most of the muropeptide products that SleB generates are large and are potential substrates for other GSLEs present in the spore. Study of a truncated protein revealed that SleB has two domains. The N-terminal domain is required for stable peptidoglycan binding, while the C-terminal domain is the region of peptidoglycan hydrolytic activity. The C-terminal domain also exhibits dependence on cortex containing muramic-δ-lactam in order to carry out hydrolysis. As the conditions and limitations for SleB activity are further elucidated, they will enable the development of treatments that stimulate premature germination of B. anthracis spores, greatly simplifying decontamination measures.
Collapse
|
23
|
Abstract
Molecular-genetic and muropeptide analysis techniques have been applied to examine the function in vivo of the Bacillus megaterium QM B1551 SleB and SleL proteins. In common with Bacillus subtilis and Bacillus anthracis, the presence of anhydromuropeptides in B. megaterium germination exudates, which is indicative of lytic transglycosylase activity, is associated with an intact sleB structural gene. B. megaterium sleB cwlJ double mutant strains complemented with engineered SleB variants in which the predicted N- or C-terminal domain has been deleted (SleB-ΔN or SleB-ΔC) efficiently initiate and hydrolyze the cortex, generating anhydromuropeptides in the process. Additionally, sleB cwlJ strains complemented with SleB-ΔN or SleB-ΔC, in which glutamate and aspartate residues have individually been changed to alanine, all retain the ability to hydrolyze the cortex to various degrees during germination, with concomitant release of anhydromuropeptides to the surrounding medium. These data indicate that while the presence of either the N- or C-terminal domain of B. megaterium SleB is sufficient for initiation of cortex hydrolysis and the generation of anhydromuropeptides, the perceived lytic transglycosylase activity may be derived from an enzyme(s), perhaps exclusively or in addition to SleB, which has yet to be identified. B. megaterium SleL appears to be associated with the epimerase-type activity observed previously in B. subtilis, differing from the glucosaminidase function that is apparent in B. cereus/B. anthracis.
Collapse
|
24
|
Boniface A, Parquet C, Arthur M, Mengin-Lecreulx D, Blanot D. The elucidation of the structure of Thermotoga maritima peptidoglycan reveals two novel types of cross-link. J Biol Chem 2009; 284:21856-21862. [PMID: 19542229 DOI: 10.1074/jbc.m109.034363] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Thermotoga maritima is a Gram-negative, hyperthermophilic bacterium whose peptidoglycan contains comparable amounts of L- and D-lysine. We have determined the fine structure of this cell-wall polymer. The muropeptides resulting from the digestion of peptidoglycan by mutanolysin were separated by high-performance liquid chromatography and identified by amino acid analysis after acid hydrolysis, dinitrophenylation, enzymatic determination of the configuration of the chiral amino acids, and mass spectrometry. The high-performance liquid chromatography profile contained four main peaks, two monomers, and two dimers, plus a few minor peaks corresponding to anhydro forms. The first monomer was the d-lysine-containing disaccharide-tripeptide in which the D-Glu-D-Lys bond had the unusual gamma-->epsilon arrangement (GlcNAc-MurNAc-L-Ala-gamma-D-Glu-epsilon-D-Lys). The second monomer was the conventional disaccharide-tetrapeptide (GlcNAc-MurNAc-L-Ala-gamma-D-Glu-L-Lys-D-Ala). The first dimer contained a disaccharide-L-Ala as the acyl donor cross-linked to the alpha-amine of D-Lys in a tripeptide acceptor stem with the sequence of the first monomer. In the second dimer, donor and acceptor stems with the sequences of the second and first monomers, respectively, were connected by a D-Ala4-alpha-D-Lys3 cross-link. The cross-linking index was 10 with an average chain length of 30 disaccharide units. The structure of the peptidoglycan of T. maritima revealed for the first time the key role of D-Lys in peptidoglycan synthesis, both as a surrogate of L-Lys or meso-diaminopimelic acid at the third position of peptide stems and in the formation of novel cross-links of the L-Ala1(alpha-->alpha)D-Lys3 and D-Ala4(alpha-->alpha)D-Lys3 types.
Collapse
Affiliation(s)
- Audrey Boniface
- Laboratoire des Enveloppes Bactériennes et Antibiotiques, Institut de Biochimie et Biophysique Moléculaire et Cellulaire, Université Paris-Sud, 91405 Orsay; CNRS, UMR 8619, 91405 Orsay
| | - Claudine Parquet
- Laboratoire des Enveloppes Bactériennes et Antibiotiques, Institut de Biochimie et Biophysique Moléculaire et Cellulaire, Université Paris-Sud, 91405 Orsay; CNRS, UMR 8619, 91405 Orsay
| | - Michel Arthur
- Centre de Recherche des Cordeliers, Laboratoire de Recherche Moléculaire sur les Antibiotiques, Université Pierre et Marie Curie, UMR S 872, 75006 Paris; Université Paris-Descartes, UMR S 872, 75006 Paris; INSERM, U872, 75006 Paris, France
| | - Dominique Mengin-Lecreulx
- Laboratoire des Enveloppes Bactériennes et Antibiotiques, Institut de Biochimie et Biophysique Moléculaire et Cellulaire, Université Paris-Sud, 91405 Orsay; CNRS, UMR 8619, 91405 Orsay
| | - Didier Blanot
- Laboratoire des Enveloppes Bactériennes et Antibiotiques, Institut de Biochimie et Biophysique Moléculaire et Cellulaire, Université Paris-Sud, 91405 Orsay; CNRS, UMR 8619, 91405 Orsay
| |
Collapse
|
25
|
Roles of germination-specific lytic enzymes CwlJ and SleB in Bacillus anthracis. J Bacteriol 2009; 191:2237-47. [PMID: 19181808 DOI: 10.1128/jb.01598-08] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
The structural characteristics of a spore enable it to withstand stresses that typically kill a vegetative cell. Spores remain dormant until small molecule signals induce them to germinate into vegetative bacilli. Germination requires degradation of the thick cortical peptidoglycan by germination-specific lytic enzymes (GSLEs). Bacillus anthracis has four putative GSLEs, based upon sequence similarities with enzymes in other species: SleB, CwlJ1, CwlJ2, and SleL. In this study, the roles of SleB, CwlJ1, and CwlJ2 were examined. The expression levels of all three genes peak 3.5 h into sporulation. Genetic analysis revealed that, similar to other known GSLEs, none of these gene products are individually required for growth, sporulation, or triggering of germination. However, later germination events are affected in spores lacking CwlJ1 or SleB. Compared to the wild type, germinating spores without CwlJ1 suffer a delay in optical density loss and cortex peptidoglycan release. The absence of SleB also causes a delay in cortex fragment release. A double mutant lacking both SleB and CwlJ1 is completely blocked in cortex hydrolysis and progresses through outgrowth to produce colonies at a frequency 1,000-fold lower than that of the wild-type strain. A null mutation eliminating CwlJ2 has no effect on germination. High-performance liquid chromatography and mass spectroscopy analysis revealed that SleB is required for lytic transglycosylase activity. CwlJ1 also clearly participates in cortex hydrolysis, but its specific mode of action remains unclear. Understanding the lytic germination activities that naturally diminish spore resistance can lead to methods for prematurely inducing them, thus simplifying the process of treating contaminated sites.
Collapse
|
26
|
The Bacillus anthracis SleL (YaaH) protein is an N-acetylglucosaminidase involved in spore cortex depolymerization. J Bacteriol 2008; 190:7601-7. [PMID: 18835992 DOI: 10.1128/jb.01054-08] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Bacillus anthracis spores, the infectious agents of anthrax, are notoriously difficult to remove from contaminated areas because they are resistant to many eradication methods. These resistance properties are due to the spore's dehydration and dormancy and to the multiple protective layers surrounding the spore core, one of which is the cortex. In order for B. anthracis spores to germinate and resume growth, the cortex peptidoglycan must be depolymerized. This study reports on analyses of sleL (yaaH), which encodes a cortex-lytic enzyme. The inactivation of sleL does not affect vegetative growth, spore viability, or the initial stages of germination, including dipicolinic acid release. However, mutant spores exhibit a slight delay in the loss of optical density compared to that of wild-type spores. Mutants also retain more diaminopimelic acid and N-acetylmuramic acid during germination than wild-type spores, suggesting that the cortex peptidoglycan is not being hydrolyzed as rapidly. This finding is supported by high-pressure liquid chromatography analysis of the peptidoglycan structure used to confirm that SleL acts as an N-acetylglucosaminidase. When sleL is inactivated, the cortex peptidoglycan is not depolymerized into small muropeptides but instead is retained within the spore as large fragments. In the absence of the sleL-encoded N-acetylglucosaminidase, other cortex-lytic enzymes break down the cortex peptidoglycan sufficiently to allow rapid germination and outgrowth.
Collapse
|
27
|
Effect of the osmotic conditions during sporulation on the subsequent resistance of bacterial spores. Appl Microbiol Biotechnol 2008; 80:107-14. [DOI: 10.1007/s00253-008-1519-x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2008] [Revised: 03/14/2008] [Accepted: 04/21/2008] [Indexed: 10/22/2022]
|
28
|
Bacterial growth and cell division: a mycobacterial perspective. Microbiol Mol Biol Rev 2008; 72:126-56, table of contents. [PMID: 18322037 DOI: 10.1128/mmbr.00028-07] [Citation(s) in RCA: 271] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The genus Mycobacterium is best known for its two major pathogenic species, M. tuberculosis and M. leprae, the causative agents of two of the world's oldest diseases, tuberculosis and leprosy, respectively. M. tuberculosis kills approximately two million people each year and is thought to latently infect one-third of the world's population. One of the most remarkable features of the nonsporulating M. tuberculosis is its ability to remain dormant within an individual for decades before reactivating into active tuberculosis. Thus, control of cell division is a critical part of the disease. The mycobacterial cell wall has unique characteristics and is impermeable to a number of compounds, a feature in part responsible for inherent resistance to numerous drugs. The complexity of the cell wall represents a challenge to the organism, requiring specialized mechanisms to allow cell division to occur. Besides these mycobacterial specializations, all bacteria face some common challenges when they divide. First, they must maintain their normal architecture during and after cell division. In the case of mycobacteria, that means synthesizing the many layers of complex cell wall and maintaining their rod shape. Second, they need to coordinate synthesis and breakdown of cell wall components to maintain integrity throughout division. Finally, they need to regulate cell division in response to environmental stimuli. Here we discuss these challenges and the mechanisms that mycobacteria employ to meet them. Because these organisms are difficult to study, in many cases we extrapolate from information known for gram-negative bacteria or more closely related GC-rich gram-positive organisms.
Collapse
|
29
|
Cortex peptidoglycan lytic activity in germinating Bacillus anthracis spores. J Bacteriol 2008; 190:4541-8. [PMID: 18456807 DOI: 10.1128/jb.00249-08] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Bacterial endospore dormancy and resistance properties depend on the relative dehydration of the spore core, which is maintained by the spore membrane and its surrounding cortex peptidoglycan wall. During spore germination, the cortex peptidoglycan is rapidly hydrolyzed by lytic enzymes packaged into the dormant spore. The peptidoglycan structures in both dormant and germinating Bacillus anthracis Sterne spores were analyzed. The B. anthracis dormant spore peptidoglycan was similar to that found in other species. During germination, B. anthracis released peptidoglycan fragments into the surrounding medium more quickly than some other species. A major lytic enzymatic activity was a glucosaminidase, probably YaaH, that cleaved between N-acetylglucosamine and muramic-delta-lactam. An epimerase activity previously proposed to function on spore peptidoglycan was not detected, and it is proposed that glucosaminidase products were previously misidentified as epimerase products. Spore cortex lytic enzymes and their regulators are attractive targets for development of germination inhibitors to kill spores and for development of activators to cause loss of resistance properties for decontamination of spore release sites.
Collapse
|
30
|
Vollmer W, Joris B, Charlier P, Foster S. Bacterial peptidoglycan (murein) hydrolases. FEMS Microbiol Rev 2008; 32:259-86. [PMID: 18266855 DOI: 10.1111/j.1574-6976.2007.00099.x] [Citation(s) in RCA: 609] [Impact Index Per Article: 38.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Most bacteria have multiple peptidoglycan hydrolases capable of cleaving covalent bonds in peptidoglycan sacculi or its fragments. An overview of the different classes of peptidoglycan hydrolases and their cleavage sites is provided. The physiological functions of these enzymes include the regulation of cell wall growth, the turnover of peptidoglycan during growth, the separation of daughter cells during cell division and autolysis. Specialized hydrolases enlarge the pores in the peptidoglycan for the assembly of large trans-envelope complexes (pili, flagella, secretion systems), or they specifically cleave peptidoglycan during sporulation or spore germination. Moreover, peptidoglycan hydrolases are involved in lysis phenomena such as fratricide or developmental lysis occurring in bacterial populations. We will also review the current view on the regulation of autolysins and on the role of cytoplasm hydrolases in peptidoglycan recycling and induction of beta-lactamase.
Collapse
Affiliation(s)
- Waldemar Vollmer
- Institute for Cell and Molecular Biosciences, University of Newcastle upon Tyne, Newcastle upon Tyne, UK.
| | | | | | | |
Collapse
|
31
|
Hett EC, Chao MC, Steyn AJ, Fortune SM, Deng LL, Rubin EJ. A partner for the resuscitation-promoting factors of Mycobacterium tuberculosis. Mol Microbiol 2007; 66:658-68. [DOI: 10.1111/j.1365-2958.2007.05945.x] [Citation(s) in RCA: 119] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
|
32
|
Temmerman R, Vervaeren H, Noseda B, Boon N, Verstraete W. Inhibition ofLegionella pneumophila byBacillus sp. Eng Life Sci 2007. [DOI: 10.1002/elsc.200620212] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
|
33
|
Vasudevan P, Weaver A, Reichert ED, Linnstaedt SD, Popham DL. Spore cortex formation in Bacillus subtilis is regulated by accumulation of peptidoglycan precursors under the control of sigma K. Mol Microbiol 2007; 65:1582-94. [PMID: 17714441 DOI: 10.1111/j.1365-2958.2007.05896.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The bacterial endospore cortex peptidoglycan is synthesized between the double membranes of the developing forespore and is required for attainment of spore dehydration and dormancy. The Bacillus subtilis spoVB, spoVD and spoVE gene products are expressed in the mother cell compartment early during sporulation and play roles in cortex synthesis. Here we show that mutations in these genes block synthesis of cortex peptidoglycan and cause accumulation of peptidoglycan precursors, indicating a defect at the earliest steps of peptidoglycan polymerization. Loss of spoIV gene products involved in activation of later, sigma(K)-dependent mother cell gene expression results in decreased synthesis of cortex peptidoglycan, even in the presence of the SpoV proteins that were synthesized earlier, apparently due to decreased precursor production. Data show that activation of sigma(K) is required for increased synthesis of the soluble peptidoglycan precursors, and Western blot analyses show that increases in the precursor synthesis enzymes MurAA, MurB, MurC and MurF are dependent on sigma(K) activation. Overall, our results indicate that a decrease in peptidoglycan precursor synthesis during early sporulation, followed by renewed precursor synthesis upon sigma(K) activation, serves as a regulatory mechanism for the timing of spore cortex synthesis.
Collapse
Affiliation(s)
- Pradeep Vasudevan
- Department of Biological Sciences, Virginia Tech, 2119 Derring Hall MC0406, Blacksburg, VA 24061, USA
| | | | | | | | | |
Collapse
|
34
|
Kumazawa T, Masayama A, Fukuoka S, Makino S, Yoshimura T, Moriyama R. Mode of action of a germination-specific cortex-lytic enzyme, SleC, of Clostridium perfringens S40. Biosci Biotechnol Biochem 2007; 71:884-92. [PMID: 17420590 DOI: 10.1271/bbb.60511] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The hydrolysis of the bacterial spore peptidoglycan (cortex) is a crucial event in spore germination. It has been suggested that SleC and SleM, which are conserved among clostridia, are to be considered putative cortex-lytic enzymes in Clostridium perfringens. However, little is known about the details of the hydrolytic process by these enzymes during germination, except that SleM functions as a muramidase. Muropeptides derived from SleC-digested decoated spores of a Bacillus subtilis mutant that lacks the enzymes, SleB, YaaH and CwlJ, related to cortex hydrolysis were identified by amino acid analysis and mass spectrometry. The results suggest that SleC is most likely a bifunctional enzyme possessing lytic transglycosylase activity and N-acetylmuramoyl-L-alanine amidase activity confined to cross-linked tetrapeptide-tetrapeptide moieties of the cortex structure. Furthermore, it appears that during germination of Clostridium perfringens spores, SleC causes merely small and local changes in the cortex structure, which are necessary before SleM can function.
Collapse
Affiliation(s)
- Toshihiko Kumazawa
- Department of Applied Molecular Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan
| | | | | | | | | | | |
Collapse
|
35
|
Hu K, Yang H, Liu G, Tan H. Identification and characterization of a polysaccharide deacetylase gene from Bacillus thuringiensis. Can J Microbiol 2007; 52:935-41. [PMID: 17110961 DOI: 10.1139/w06-045] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
One polysaccharide deacetylase gene was cloned from Bacillus thuringiensis and designated pdaA. Disruption of pdaA did not affect vegetative growth and sporulation but obviously affected spore germination. When L-alanine was added into the spore suspension, the spores of the pdaA disruption mutant showed a slow and partial reduction in absorbance at OD600 and became phase pale gray compared with phase dark of the wild-type strain. In contrast with the outgrowing of wild-type spores after germination, the pdaA mutant spores were blocked at the stage of spore germination. Transmission electron micrographs revealed a significant difference between the pdaA mutant and the wild-type strain in the spore cortex. Introduction of the pdaA gene into the pdaA disruption mutant complemented the germination-negative phenotype. Reverse transcription--polymerase chain reaction showed that pdaA was transcribed after incubation for 10 h in CCY medium.
Collapse
Affiliation(s)
- Kun Hu
- Institute of Microbiology, Chinese Academy of Science, Beijing, PR China
| | | | | | | |
Collapse
|
36
|
Gai Y, Liu G, Tan H. Identification and characterization of a germination operon from Bacillus thuringiensis. Antonie Van Leeuwenhoek 2006; 89:251-9. [PMID: 16710636 DOI: 10.1007/s10482-005-9026-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2005] [Accepted: 11/30/2005] [Indexed: 10/24/2022]
Abstract
Spore cortex-lytic enzymes are essential for germination in Bacillus. A homologue of the cwlJ gene involved in spore germination was isolated from Bacillus thuringiensis. The deduced product of this gene exhibits striking sequence similarity to CwlJ of Bacillus subtilis. Another open reading frame (ORF) was found 27 bp downstream of cwlJ and its deduced product shows high similarity to YwdL of B. subtilis. Reverse transcription polymerase chain reaction analysis indicated that cwlJ and ywdL formed a bicistronic operon in B. thuringiensis. Disruption of this operon did not affect sporulation and the spores of corresponding mutant showed the same refractility as the wild-type strain. In contrast, the fall of optical density at 600 nm in the mutant culture was slower than that of the wild-type strain during the spore germination response to different germinants such as L: -alanine, inosine or CaDPA. The spore germination of the cwlJ mutant was restored by introducing this operon into the disruption mutant. These results suggest this operon is essential for normal spore germination in B. thuringiensis. The expression of cwlJ was observed in the sporulating cells through Western blot experiments.
Collapse
Affiliation(s)
- Yuling Gai
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Science, Beijing, 100080, P.R. China
| | | | | |
Collapse
|
37
|
Stecchini ML, Del Torre M, Venir E, Morettin A, Furlan P, Maltini E. Glassy state in Bacillus subtilis spores analyzed by differential scanning calorimetry. Int J Food Microbiol 2006; 106:286-90. [PMID: 16257078 DOI: 10.1016/j.ijfoodmicro.2005.06.028] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2004] [Revised: 04/01/2005] [Accepted: 06/30/2005] [Indexed: 10/25/2022]
Abstract
Thermal properties of dried spores of Bacillus subtilis, investigated by differential scanning calorimetry (DSC), were studied. A reversible heat capacity shift ascribable to glass-rubber transition was observed at 90-115 degrees C. The transition was found to be a pressure-inhibited volume-activated event. The decoated spores and the extracted peptidoglycan material exhibited glass transition, suggesting that the cortex could be involved in the event. Furthermore, the glass transition was evident when spores were treated with strong acid, and when the isogenic strain PS578 was scanned, indicating that core integrity and core components are not involved in the occurrence of the event. These results suggest that in the dried B. subtilis spores an amorphous biomaterial, possibly the cortex peptidoglycan, is present as a glass.
Collapse
Affiliation(s)
- Mara Lucia Stecchini
- Department of Food Science, University of Udine, Via Marangoni n. 97, 33100 Udine, Italy.
| | | | | | | | | | | |
Collapse
|
38
|
Masayama A, Fukuoka H, Kato S, Yoshimura T, Moriyama M, Moriyama R. Subcellular Localization of a Germiantion-specific Cortex-lytic Enzyme, SleB, of Bacilli during Sporulation. Genes Genet Syst 2006; 81:163-9. [PMID: 16905870 DOI: 10.1266/ggs.81.163] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
The subcellular localization of a germination-specific cortex-lytic enzyme, SleB, of Bacillus subtilis during sporulation was observed by using fusions of N-terminal region of SleB to the green fluorescent protein (GFP). A fusion with a putative peptidoglycan-binding motif (SleB1-108-GFP) formed a fluorescent ring around the forespore of the wild type strain, as expected from the known location of the intact SleB in the dormant spore. SleB1-108-GFP formed a similar fluorescent ring around the forespore of the gerE mutant which has a severe defect in the coat structure, and of the cwlD mutant which lacks a muramic delta-lactam unique to the spore peptidoglycan (cortex), whereas the fusion could not attach to the spore of the cwlDgerE mutant. By contrast, a fusion without the motif (SleB1-45-GFP) could not be recruited around the forespore of the gerE mutant though it appeared to be accumulated on the outside of the spore of the wild type strain. Since SleB was shown to degrade only the cortex with muramic delta-lactam, these results suggested that a proper localization of SleB requires a strict interaction between the motif of the enzyme and the delta-lactam structure of the cortex, not the formation of normal coat layer.
Collapse
Affiliation(s)
- Atsushi Masayama
- Department of Applied Molecular Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Aichi, Japan
| | | | | | | | | | | |
Collapse
|
39
|
SASAGAWA A, YAMAZAKI A, KOBAYASHI A, HOSHINO J, OHSHIMA T, SATO M, FUJII T, YAMADA A. Inactivation of Bacillus Subtilis Spores by a Combination of Hydrostatic High-Pressure and Pulsed Electric Field Treatments. ACTA ACUST UNITED AC 2006. [DOI: 10.4131/jshpreview.16.45] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
|
40
|
Iyer JL, Shetty P, Pai J. Evaluation of whole cells of Bacillus subtilis as substrate for measurement of autolysin activity. Process Biochem 2005. [DOI: 10.1016/j.procbio.2004.06.022] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
|
41
|
Stenbak CR, Ryu JH, Leulier F, Pili-Floury S, Parquet C, Hervé M, Chaput C, Boneca IG, Lee WJ, Lemaitre B, Mengin-Lecreulx D. Peptidoglycan molecular requirements allowing detection by the Drosophila immune deficiency pathway. THE JOURNAL OF IMMUNOLOGY 2005; 173:7339-48. [PMID: 15585858 DOI: 10.4049/jimmunol.173.12.7339] [Citation(s) in RCA: 108] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Innate immune recognition of microbes is a complex process that can be influenced by both the host and the microbe. Drosophila uses two distinct immune signaling pathways, the Toll and immune deficiency (Imd) pathways, to respond to different classes of microbes. The Toll pathway is predominantly activated by Gram-positive bacteria and fungi, while the Imd pathway is primarily activated by Gram-negative bacteria. Recent work has suggested that this differential activation is achieved through peptidoglycan recognition protein (PGRP)-mediated recognition of specific forms of peptidoglycan (PG). In this study, we have further analyzed the specific PG molecular requirements for Imd activation through the pattern recognition receptor PGRP-LC in both cultured cell line and in flies. We found that two signatures of Gram-negative PG, the presence of diaminopimelic acid in the peptide bridge and a 1,6-anhydro form of N-acetylmuramic acid in the glycan chain, allow discrimination between Gram-negative and Gram-positive bacteria. Our results also point to a role for PG oligomerization in Imd activation, and we demonstrate that elements of both the sugar backbone and the peptide bridge of PG are required for optimum recognition. Altogether, these results indicate multiple requirements for efficient PG-mediated activation of the Imd pathway and demonstrate that PG is a complex immune elicitor.
Collapse
Affiliation(s)
- Carolyn R Stenbak
- Centre de Génétique Moléculaire du Centre National de la Recherche Scientifique, Gif-sur-Yvette, France
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
42
|
Wei Y, McPherson DC, Popham DL. A mother cell-specific class B penicillin-binding protein, PBP4b, in Bacillus subtilis. J Bacteriol 2004; 186:258-61. [PMID: 14679248 PMCID: PMC303456 DOI: 10.1128/jb.186.1.258-261.2004] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The Bacillus subtilis genome encodes 16 penicillin-binding proteins (PBPs), some of which are involved in synthesis of the spore peptidoglycan. The pbpI (yrrR) gene encodes a class B PBP, PBP4b, and is transcribed in the mother cell by RNA polymerase containing sigma(E). Loss of PBP4b, alone and in combination with other sporulation-specific PBPs, had no effect on spore peptidoglycan structure.
Collapse
Affiliation(s)
- Yuping Wei
- Department of Biology, Virginia Tech, Blacksburg, Virginia 24061, USA
| | | | | |
Collapse
|
43
|
Gilmore ME, Bandyopadhyay D, Dean AM, Linnstaedt SD, Popham DL. Production of muramic delta-lactam in Bacillus subtilis spore peptidoglycan. J Bacteriol 2004; 186:80-9. [PMID: 14679227 PMCID: PMC303458 DOI: 10.1128/jb.186.1.80-89.2004] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Bacterial spore heat resistance is primarily dependent upon dehydration of the spore cytoplasm, a state that is maintained by the spore peptidoglycan wall, the spore cortex. A peptidoglycan structural modification found uniquely in spores is the formation of muramic delta-lactam. Production of muramic delta-lactam in Bacillus subtilis requires removal of a peptide side chain from the N-acetylmuramic acid residue by a cwlD-encoded muramoyl-L-Alanine amidase. Expression of cwlD takes place in both the mother cell and forespore compartments of sporulating cells, though expression is expected to be required only in the mother cell, from which cortex synthesis derives. Expression of cwlD in the forespore is in a bicistronic message with the upstream gene ybaK. We show that ybaK plays no apparent role in spore peptidoglycan synthesis and that expression of cwlD in the forespore plays no significant role in spore peptidoglycan formation. Peptide cleavage by CwlD is apparently followed by deacetylation of muramic acid and lactam ring formation. The product of pdaA (yfjS), which encodes a putative deacetylase, has recently been shown to also be required for muramic delta-lactam formation. Expression of CwlD in Escherichia coli results in muramoyl L-Alanine amidase activity but no muramic delta-lactam formation. Expression of PdaA alone in E. coli had no effect on E. coli peptidoglycan structure, whereas expression of CwlD and PdaA together resulted in the formation of muramic delta-lactam. CwlD and PdaA are necessary and sufficient for muramic delta-lactam production, and no other B. subtilis gene product is required. PdaA probably carries out both deacetylation and lactam ring formation and requires the product of CwlD activity as a substrate.
Collapse
Affiliation(s)
- Meghan E Gilmore
- Department of Biology, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, USA
| | | | | | | | | |
Collapse
|
44
|
Horsburgh GJ, Atrih A, Foster SJ. Characterization of LytH, a differentiation-associated peptidoglycan hydrolase of Bacillus subtilis involved in endospore cortex maturation. J Bacteriol 2003; 185:3813-20. [PMID: 12813075 PMCID: PMC161573 DOI: 10.1128/jb.185.13.3813-3820.2003] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The cortex peptidoglycan from endospores of Bacillus subtilis is responsible for the maintenance of dormancy. LytH (YunA) has been identified as a novel sporulation-specific component with a role in cortex structure determination. The lytH gene was expressed only during sporulation, under the control of the mother cell-specific sigma factor sigma(K). Spores of a lytH mutant have slightly reduced heat resistance and altered staining when viewed by electron microscopy. Analysis of the peptidoglycan structure of lytH mutant spores shows the loss of muramic acid residues substituted with L-alanine and a corresponding increase in muramic acid residues substituted with tetrapeptide compared to those in the parent strain. In a lytH cwlD mutant, the lack of muramic acid residues substituted with L-alanine and delta-lactam leaves 97% of residues substituted with tetrapeptide. These results suggest that lytH encodes an L-Ala-D-Glu peptidase involved in production of single L-alanine side chains from tetrapeptides in the spore cortex. The lack of di- or tripeptides in a lytH mutant reveals the enzyme is an endopeptidase.
Collapse
Affiliation(s)
- Gavin J Horsburgh
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN, United Kingdom
| | | | | |
Collapse
|
45
|
Horsburgh GJ, Atrih A, Williamson MP, Foster SJ. LytG of Bacillus subtilis is a novel peptidoglycan hydrolase: the major active glucosaminidase. Biochemistry 2003; 42:257-64. [PMID: 12525152 DOI: 10.1021/bi020498c] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
LytG (YubE) of Bacillus subtilis is a novel 32 kDa autolysin produced during vegetative growth under the control of Esigma(A) RNA polymerase. Muropeptide analysis of vegetative cells of B. subtilis revealed LytG to be the major glucosaminidase responsible for peptidoglycan structural determination during vegetative growth. Overexpression and purification of LytG allowed its biochemical characterization. Despite sequence homology suggesting muramidase activity, LytG is a novel glucosaminidase with exoenzyme activity and may form part of a novel family of autolysins. It is involved in cell division, lysis, and motility on swarm plates.
Collapse
Affiliation(s)
- Gavin J Horsburgh
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield, S10 2TN, United Kingdom
| | | | | | | |
Collapse
|
46
|
Abstract
Bacillus anthracis is a Gram-positive bacterium harboring a complex parietal architecture. The cytoplasmic membrane is surrounded by a thick peptidoglycan of the A1 gamma type. Only one associated polymer, a polysaccharide composed of galactose, N-acetylglucosamine, and N-acetylmannosamine, is covalently linked to the peptidoglycan. Outside the cell wall is an S-layer. Two proteins can each compose the S-layer. They are noncovalently anchored to the cell wall polysaccharide by their SLH N-terminal domain. The poly-gamma-D-glutamate capsule, which covers the S-layer, has an antiphagocytic role and its synthesis is dependent on environmental factors mimicking the mammalian host, such as bicarbonate and a temperature of 37 degrees C.
Collapse
Affiliation(s)
- A Fouet
- Toxines et Pathogénie Bactériennes (URA 2172, CNRS), Institut Pasteur, 28 rue du Dr Roux, 75724, Paris, France.
| | | |
Collapse
|
47
|
Fukushima T, Yamamoto H, Atrih A, Foster SJ, Sekiguchi J. A polysaccharide deacetylase gene (pdaA) is required for germination and for production of muramic delta-lactam residues in the spore cortex of Bacillus subtilis. J Bacteriol 2002; 184:6007-15. [PMID: 12374835 PMCID: PMC135383 DOI: 10.1128/jb.184.21.6007-6015.2002] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The predicted amino acid sequence of Bacillus subtilis yfjS (renamed pdaA) exhibits high similarity to those of several polysaccharide deacetylases. Beta-galactosidase fusion experiments and results of Northern hybridization with sporulation sigma mutants indicated that the pdaA gene is transcribed by E(sigma)(G) RNA polymerase. pdaA-deficient spores were bright by phase-contrast microscopy, and the spores were induced to germination on the addition of L-alanine. Germination-associated spore darkening, a slow and partial decrease in absorbance, and slightly lower dipicolinic acid release compared with that by the wild-type strain were observed. In particular, the release of hexosamine-containing materials was lacking in the pdaA mutant. Muropeptide analysis indicated that the pdaA-deficient spores completely lacked muramic delta-lactam. A pdaA-gfp fusion protein constructed in strain 168 and pdaA-deficient strains indicated that the protein is localized in B. subtilis spores. The biosynthetic pathway of muramic delta-lactam is discussed.
Collapse
Affiliation(s)
- Tatsuya Fukushima
- Department of Applied Biology, Faculty of Textile Science and Technology, Shinshu University, Ueda-shi, Nagano 386, Japan
| | | | | | | | | |
Collapse
|
48
|
Chirakkal H, O'Rourke M, Atrih A, Foster SJ, Moir A. Analysis of spore cortex lytic enzymes and related proteins in Bacillus subtilis endospore germination. MICROBIOLOGY (READING, ENGLAND) 2002; 148:2383-2392. [PMID: 12177332 DOI: 10.1099/00221287-148-8-2383] [Citation(s) in RCA: 118] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The location and function of recognized cortex-lytic enzymes of Bacillus subtilis have been explored, and the involvement in germination of a number of related proteins tested. The SleB and CwlJ proteins are cortex-lytic enzymes, partially redundant in function, that are required together for effective cortex hydrolysis during B. subtilis spore germination. Spores were fractionated, and Western blotting of individual fractions suggests that the CwlJ protein is localized exclusively to the outer layers, or integument. The second spore-lytic enzyme, SleB, is localized both in the inner membrane of the spore and in the integument fraction. Neither protein changes location or size as the spore germinates. The ypeB gene is the second gene in a bicistronic operon with sleB. The SleB protein is absent from ypeB mutant spores, suggesting that YpeB is required for its localization or stabilization. In fractions of wild-type spores, the YpeB protein is found in the same locations as SleB - in both the inner membrane and the integument. As the absence of CwlJ protein does not affect the overall RP-HPLC profile of peptidoglycan fragments in germinating spores, this enzyme's hydrolytic specificity could not be defined. The effects of inactivation of several homologues of cortex-lytic enzymes of as yet undefined function were examined, by testing null mutants for their germination behaviour by OD(600) fall and by RP-HPLC of peptidoglycan fragments from dormant and germinating spores. The YaaH enzyme is responsible for a likely epimerase modification of peptidoglycan during spore germination, but the loss of this activity does not appear to affect the spore's ability to complete germination. Unlike the other cortex-lytic enzymes, the YaaH protein is present in large amounts in the spore germination exudate of B. subtilis. Mutants lacking either YdhD or YvbX, both homologues of YaaH, had no detectable alteration in either dormant or germinating spore peptidoglycan, and germinated normally. The ykvT gene, which encodes a protein of the SleB/CwlJ family, has no apparent association with germination: the gene is expressed in vegetative cells, and mutants lacking YkvT have no detectable phenotype.
Collapse
Affiliation(s)
- Haridasan Chirakkal
- Department of Molecular Biology and Biotechnology, The University of Sheffield, Sheffield S10 2TN, UK1
| | - Michele O'Rourke
- Department of Molecular Biology and Biotechnology, The University of Sheffield, Sheffield S10 2TN, UK1
| | - Abdelmadjid Atrih
- Department of Molecular Biology and Biotechnology, The University of Sheffield, Sheffield S10 2TN, UK1
| | - Simon J Foster
- Department of Molecular Biology and Biotechnology, The University of Sheffield, Sheffield S10 2TN, UK1
| | - Anne Moir
- Department of Molecular Biology and Biotechnology, The University of Sheffield, Sheffield S10 2TN, UK1
| |
Collapse
|
49
|
|
50
|
Atrih A, Foster SJ. In vivo roles of the germination-specific lytic enzymes of Bacillus subtilis 168. MICROBIOLOGY (READING, ENGLAND) 2001; 147:2925-32. [PMID: 11700343 DOI: 10.1099/00221287-147-11-2925] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Germination of endospores of Bacillus subtilis involves the activities of several germination-specific lytic enzymes, including glucosaminidase and lytic transglycosylase. Another non-hydrolytic activity, likely to be due to an epimerase, also occurs. The effect of pH on enzyme activities and the overall germination rate was measured. Optimal germination occurred between pH 7-9; however, optimum glucosaminidase and epimerase activities were noted at pH 5. Conversely, the lytic transglycosylase activity was greatest at pH 8. Treatment of spores (15 min) with heat (90 degrees C) or NaOH (0.25 M) led to impaired cortex hydrolysis/modification, but with <20% loss in viability. Analysis of muropeptides in the germination exudate revealed a reduction of >85% in glucosaminidase and epimerase products, when compared to untreated spores. Conversely, lytic transglycosylase activity was increased by alkali or heat treatment, which was possibly due to increased substrate availability. FB101 (sleB) spores, which lack lytic transglycosylase activity, showed 90-fold greater loss in viability than the wild-type after 1 h at 90 degrees C. Similarly, 97% of FB101 (sleB) spores were unable to form a colony on nutrient agar after 130 min exposure to 0.25 M NaOH at 4 degrees C, whereas the wild-type was unaffected. This demonstrates the crucial role of the lytic transglycosylase in cortex hydrolysis of damaged spores. The respective targets of heat and alkali in spores and their role during germination are discussed.
Collapse
Affiliation(s)
- A Atrih
- Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, UK
| | | |
Collapse
|