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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.
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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.
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Riyami BA, Ghosh A, Rees EJ, Christie G. Novel cortex lytic enzymes in Bacillus megaterium QM B1551 spores. FEMS Microbiol Lett 2019; 366:5527933. [DOI: 10.1093/femsle/fnz146] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Accepted: 07/02/2019] [Indexed: 11/15/2022] Open
Abstract
ABSTRACTPresent models for spore germination in Bacillus species include a requirement for either the SleB or CwlJ cortex lytic enzymes to efficiently depolymerise the spore cortex. Previous work has demonstrated that B. megaterium spores may differ to other species in this regard, since sleB cwlJ null mutant spores complemented with the gene in trans for the non-peptidoglycan lysin YpeB can efficiently degrade the cortex. Here, we identify two novel cortex lytic enzymes, encoded at the BMQ_2391 and BMQ_3234 loci, which are essential for cortex hydrolysis in the absence of SleB and CwlJ. Ellipsoid localisation microscopy places the BMQ_3234 protein within the inner-spore coat, a region of the spore that is populated by other cortex lytic enzymes. The findings reinforce the idea that there is a degree of variation in mechanisms of cortex hydrolysis across the Bacillales, raising potential implications for environmental decontamination strategies based upon targeted inactivation of components of the spore germination apparatus.
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Affiliation(s)
- Bahja Al Riyami
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, CB3 0AS, UK
| | - Abhinaba Ghosh
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, CB3 0AS, UK
| | - Eric J Rees
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, CB3 0AS, UK
| | - Graham Christie
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, CB3 0AS, UK
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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.
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Abstract
Despite being resistant to a variety of environmental insults, the bacterial endospore can sense the presence of small molecules and respond by germinating, losing the specialized structures of the dormant spore, and resuming active metabolism, before outgrowing into vegetative cells. Our current level of understanding of the spore germination process in bacilli and clostridia is reviewed, with particular emphasis on the germinant receptors characterized in Bacillus subtilis, Bacillus cereus, and Bacillus anthracis. The recent evidence for a local clustering of receptors in a "germinosome" would begin to explain how signals from different receptors could be integrated. The SpoVA proteins, involved in the uptake of Ca2+-dipicolinic acid into the forespore during sporulation, are also responsible for its release during germination. Lytic enzymes SleB and CwlJ, found in bacilli and some clostridia, hydrolyze the spore cortex: other clostridia use SleC for this purpose. With genome sequencing has come the appreciation that there is considerable diversity in the setting for the germination machinery between bacilli and clostridia.
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Abstract
Dormant Bacillales and Clostridiales spores begin to grow when small molecules (germinants) trigger germination, potentially leading to food spoilage or disease. Germination-specific proteins sense germinants, transport small molecules, and hydrolyze specific bonds in cortex peptidoglycan and specific proteins. Major events in germination include (a) germinant sensing; (b) commitment to germinate; (c) release of spores' depot of dipicolinic acid (DPA); (d) hydrolysis of spores' peptidoglycan cortex; and (e) spore core swelling and water uptake, cell wall peptidoglycan remodeling, and restoration of core protein and inner spore membrane lipid mobility. Germination is similar between Bacillales and Clostridiales, but some species differ in how germinants are sensed and how cortex hydrolysis and DPA release are triggered. Despite detailed knowledge of the proteins and signal transduction pathways involved in germination, precisely what some germination proteins do and how they do it remain unclear.
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Affiliation(s)
- Peter Setlow
- Molecular Biology and Biophysics, UConn Health, Farmington, Connecticut 06030-3305;
| | - Shiwei Wang
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China;
| | - Yong-Qing Li
- Department of Physics, East Carolina University, Greenville, North Carolina 27858-4353;
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Al-Riyami B, Üstok FI, Stott K, Chirgadze DY, Christie G. The crystal structure of Clostridium perfringens SleM, a muramidase involved in cortical hydrolysis during spore germination. Proteins 2016; 84:1681-1689. [PMID: 27488615 DOI: 10.1002/prot.25112] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Revised: 07/05/2016] [Accepted: 07/25/2016] [Indexed: 01/10/2023]
Abstract
Clostridium perfringens spores employ two peptidoglycan lysins to degrade the spore cortex during germination. SleC initiates cortex hydrolysis to generate cortical fragments that are degraded further by the muramidase SleM. Here, we present the crystal structure of the C. perfringens S40 SleM protein at 1.8 Å. SleM comprises an N-terminal catalytic domain that adopts an irregular α/β-barrel fold that is common to GH25 family lysozymes, plus a C-terminal fibronectin type III domain. The latter is involved in forming the SleM dimer that is evident in both the crystal structure and in solution. A truncated form of SleM that lacks the FnIII domain shows reduced activity against spore sacculi indicating that this domain may have a role in facilitating the position of substrate with respect to the enzyme's active site. Proteins 2016; 84:1681-1689. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Bahja Al-Riyami
- Department of Chemical Engineering and Biotechnology, Institute of Biotechnology, University of Cambridge, Cambridge, United Kingdom
| | - Fatma Işık Üstok
- Department of Haematology, Division of Structural Medicine and Thrombosis Research Unit, Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom
| | - Katherine Stott
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
| | - Dimitri Y Chirgadze
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
| | - Graham Christie
- Department of Chemical Engineering and Biotechnology, Institute of Biotechnology, University of Cambridge, Cambridge, United Kingdom.
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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
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Vandini A, Temmerman R, Frabetti A, Caselli E, Antonioli P, Balboni PG, Platano D, Branchini A, Mazzacane S. Hard surface biocontrol in hospitals using microbial-based cleaning products. PLoS One 2014; 9:e108598. [PMID: 25259528 PMCID: PMC4178175 DOI: 10.1371/journal.pone.0108598] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2014] [Accepted: 08/23/2014] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND Healthcare-Associated Infections (HAIs) are one of the most frequent complications occurring in healthcare facilities. Contaminated environmental surfaces provide an important potential source for transmission of many healthcare-associated pathogens, thus indicating the need for new and sustainable strategies. AIM This study aims to evaluate the effect of a novel cleaning procedure based on the mechanism of biocontrol, on the presence and survival of several microorganisms responsible for HAIs (i.e. coliforms, Staphyloccus aureus, Clostridium difficile, and Candida albicans) on hard surfaces in a hospital setting. METHODS The effect of microbial cleaning, containing spores of food grade Bacillus subtilis, Bacillus pumilus and Bacillus megaterium, in comparison with conventional cleaning protocols, was evaluated for 24 weeks in three independent hospitals (one in Belgium and two in Italy) and approximately 20000 microbial surface samples were collected. RESULTS Microbial cleaning, as part of the daily cleaning protocol, resulted in a reduction of HAI-related pathogens by 50 to 89%. This effect was achieved after 3-4 weeks and the reduction in the pathogen load was stable over time. Moreover, by using microbial or conventional cleaning alternatively, we found that this effect was directly related to the new procedure, as indicated by the raise in CFU/m2 when microbial cleaning was replaced by the conventional procedure. Although many questions remain regarding the actual mechanisms involved, this study demonstrates that microbial cleaning is a more effective and sustainable alternative to chemical cleaning and non-specific disinfection in healthcare facilities. CONCLUSIONS This study indicates microbial cleaning as an effective strategy in continuously lowering the number of HAI-related microorganisms on surfaces. The first indications on the actual level of HAIs in the trial hospitals monitored on a continuous basis are very promising, and may pave the way for a novel and cost-effective strategy to counteract or (bio)control healthcare-associated pathogens.
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Affiliation(s)
- Alberta Vandini
- CIAS Laboratory, Centre for the Study of physical, chemical and microbiological Contamination of Highly Sterile Environments, Department of Architecture, University of Ferrara, Ferrara, Italy
| | - Robin Temmerman
- Laboratory of Microbial Ecology and Technology, Ghent University, Ghent, Belgium
- Chrisal R & D Department, Lommel, Belgium
| | - Alessia Frabetti
- CIAS Laboratory, Centre for the Study of physical, chemical and microbiological Contamination of Highly Sterile Environments, Department of Architecture, University of Ferrara, Ferrara, Italy
| | - Elisabetta Caselli
- Department of Medical Sciences, Microbiology Section, University of Ferrara, Ferrara, Italy
| | - Paola Antonioli
- Department of Infection Prevention Control and Risk Management, Ferrara University Hospital, Ferrara, Italy
| | - Pier Giorgio Balboni
- Department of Medical Sciences, Microbiology Section, University of Ferrara, Ferrara, Italy
| | - Daniela Platano
- Department of Biomedical and Neuromotor Sciences, University of Bologna, Bologna, Italy
| | - Alessio Branchini
- Department of Life Sciences and Biotechnology, University of Ferrara, Ferrara, Italy
| | - Sante Mazzacane
- CIAS Laboratory, Centre for the Study of physical, chemical and microbiological Contamination of Highly Sterile Environments, Department of Architecture, University of Ferrara, Ferrara, Italy
- * E-mail:
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Manetsberger J, Hall EAH, Christie G. BMQ_0737 encodes a novel protein crucial to the integrity of the outermost layers of Bacillus megaterium QM B1551 spores. FEMS Microbiol Lett 2014; 358:162-9. [PMID: 24974944 DOI: 10.1111/1574-6968.12520] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2014] [Accepted: 06/24/2014] [Indexed: 11/29/2022] Open
Abstract
Bioinformatic and electron microscopy analyses indicate that the composition of the B. megaterium QM B1551 spore coat is likely to differ substantially from other Bacillus species. We report here on the identification and characterisation of novel B. megaterium proteins that appear to be abundant in the spore coat. All three proteins, encoded by loci BMQ_0737, BMQ_3035 and BMQ_4051, were identified by proteomic analysis of alkaline detergent extracts from mature spores. Putative spore coat proteins were characterised by transcriptional, reporter-fusion and mutagenesis analyses supported by fluorescence and transmission electron microscopy. These analyses revealed that BMQ_0737 is a novel morphogenetic protein that is required for the correct assembly of the B. megaterium outer spore coat and exosporium, both of which are structurally compromised or missing in BMQ_0737 null mutant spores.
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Affiliation(s)
- Julia Manetsberger
- Department of Chemical Engineering and Biotechnology, Institute of Biotechnology, University of Cambridge, Cambridge, UK
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