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Shen A, Tamayo R. Editorial overview: Gene regulation mechanisms governing Clostridioides difficile physiology and virulence. Curr Opin Microbiol 2022; 67:102139. [PMID: 35231749 DOI: 10.1016/j.mib.2022.02.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Affiliation(s)
- Aimee Shen
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA, USA.
| | - Rita Tamayo
- Department of Microbiology and Immunology, University of North Carolina Chapel Hill School of Medicine, Chapel Hill, NC, USA.
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2
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Dhungel BA, Govind R. Phase-variable expression of pdcB, a phosphodiesterase, influences sporulation in Clostridioides difficile. Mol Microbiol 2021; 116:1347-1360. [PMID: 34606654 DOI: 10.1111/mmi.14828] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Revised: 09/30/2021] [Accepted: 10/01/2021] [Indexed: 02/07/2023]
Abstract
Clostridioides difficile is the causative agent of antibiotic-associated diarrhea and is the leading cause of nosocomial infection in developed countries. An increasing number of C. difficile infections are attributed to epidemic strains that produce more toxins and spores. C. difficile spores are the major factor for the transmission and persistence of the organism. Previous studies have identified global regulators that influence sporulation in C. difficile. This study discovers that PdcB, a phosphodiesterase, enhances sporulation in C. difficile strain UK1. Through genetic and biochemical assays, we show that phase-variable expression of pdcB results in hypo- and hyper-sporulation phenotypes. In the "ON" orientation, the identified promotor is in the right orientation to drive the expression of pdcB. Production of the PdcB phosphodiesterase reduces the intracellular cyclic-di-GMP (c-di-GMP) concentration, resulting in a hyper-sporulation phenotype. Loss of PdcB due to the pdcB promoter being in the OFF orientation or mutation of pdcB results in increased c-di-GMP levels and a hypo-sporulation phenotype. Additionally, we demonstrate that CodY binds to the upstream region of pdcB. DNA inversion reorients the CodY binding site so that in the OFF orientation, CodY binds a site that is upstream of the pdcB promoter and can further repress gene expression.
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Affiliation(s)
| | - Revathi Govind
- Division of Biology, Kansas State University, Manhattan, Kansas, USA
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3
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Hasan MK, Dhungel BA, Govind R. Characterization of an operon required for growth on cellobiose in Clostridioides difficile. MICROBIOLOGY (READING, ENGLAND) 2021; 167:001079. [PMID: 34410904 PMCID: PMC8489589 DOI: 10.1099/mic.0.001079] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2021] [Accepted: 07/19/2021] [Indexed: 12/19/2022]
Abstract
Cellobiose metabolism is linked to the virulence properties in numerous bacterial pathogens. Here, we characterized a putative cellobiose PTS operon of Clostridiodes difficile to investigate the role of cellobiose metabolism in C. difficile pathogenesis. Our gene knockout experiments demonstrated that the putative cellobiose operon enables uptake of cellobiose into C. difficile and allows growth when cellobiose is provided as the sole carbon source in minimal medium. Additionally, using reporter gene fusion assays and DNA pulldown experiments, we show that its transcription is regulated by CelR, a novel transcriptional repressor protein, which directly binds to the upstream region of the cellobiose operon to control its expression. We have also identified cellobiose metabolism to play a significant role in C. difficile physiology as observed by the reduction of sporulation efficiency when cellobiose uptake was compromised in the mutant strain. In corroboration to in vitro study findings, our in vivo hamster challenge experiment showed a significant reduction of pathogenicity by the cellobiose mutant strain in both the primary and the recurrent infection model - substantiating the role of cellobiose metabolism in C. difficile pathogenesis.
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Affiliation(s)
- Md Kamrul Hasan
- Division of Biology, Kansas State University, Manhattan, KS, 66506, USA
| | | | - Revathi Govind
- Division of Biology, Kansas State University, Manhattan, KS, 66506, USA
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4
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Pichlo C, Juetten L, Wojtalla F, Schacherl M, Diaz D, Baumann U. Molecular determinants of the mechanism and substrate specificity of Clostridium difficile proline-proline endopeptidase-1. J Biol Chem 2019; 294:11525-11535. [PMID: 31182482 DOI: 10.1074/jbc.ra119.009029] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Revised: 05/27/2019] [Indexed: 11/06/2022] Open
Abstract
Pro-Pro endopeptidase-1 (PPEP-1) is a secreted metalloprotease from the bacterial pathogen Clostridium difficile that cleaves two endogenous adhesion proteins. PPEP-1 is therefore important for bacterial motility and hence for efficient gut colonization during infection. PPEP-1 exhibits a unique specificity for Pro-Pro peptide bonds within the consensus sequence VNP↓PVP. In this study, we combined information from crystal and NMR structures with mutagenesis and enzyme kinetics to investigate the mechanism and substrate specificity of PPEP-1. Our analyses revealed that the substrate-binding cleft of PPEP-1 is shaped complementarily to the major conformation of the substrate in solution. We found that it possesses features that accept a tertiary amide and help discriminate P1' residues by their amide hydrogen bond-donating potential. We also noted that residues Lys-101, Trp-103, and Glu-184 are crucial for proteolytic activity. Upon substrate binding, these residues position a flexible loop over the substrate-binding cleft and modulate the second coordination sphere of the catalytic zinc ion. On the basis of these findings, we propose an induced-fit model in which prestructured substrates are recognized followed by substrate positioning within the active-site cleft and a concomitant increase in the Lewis acidity of the catalytic Zn2+ ion. In conclusion, our findings provide detailed structural and mechanistic insights into the substrate recognition and specificity of PPEP-1 from the common gut pathogen C. difficile.
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Affiliation(s)
- Christian Pichlo
- Department of Chemistry, Institute of Biochemistry, University of Cologne, 50674 Cologne, Germany
| | - Linda Juetten
- Department of Chemistry, Institute of Organic Chemistry, University of Cologne, 50939 Cologne, Germany
| | - Fabian Wojtalla
- Department of Chemistry, Institute of Biochemistry, University of Cologne, 50674 Cologne, Germany
| | - Magdalena Schacherl
- Department of Chemistry, Institute of Biochemistry, University of Cologne, 50674 Cologne, Germany
| | - Dolores Diaz
- Department of Chemistry, Institute of Organic Chemistry, University of Cologne, 50939 Cologne, Germany
| | - Ulrich Baumann
- Department of Chemistry, Institute of Biochemistry, University of Cologne, 50674 Cologne, Germany
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5
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Guo Y, Huang ZP, Liu CQ, Qi L, Sheng Y, Zou DJ. Modulation of the gut microbiome: a systematic review of the effect of bariatric surgery. Eur J Endocrinol 2018; 178:43-56. [PMID: 28916564 DOI: 10.1530/eje-17-0403] [Citation(s) in RCA: 123] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Revised: 08/14/2017] [Accepted: 09/15/2017] [Indexed: 12/24/2022]
Abstract
OBJECTIVE Bariatric surgery is recommended for patients with obesity and type 2 diabetes. Recent evidence suggested a strong connection between gut microbiota and bariatric surgery. DESIGN Systematic review. METHODS The PubMed and OVID EMBASE were used, and articles concerning bariatric surgery and gut microbiota were screened. The main outcome measures were alterations of gut microbiota after bariatric surgery and correlations between gut microbiota and host metabolism. We applied the system of evidence level to evaluate the alteration of microbiota. Modulation of short-chain fatty acid and gut genetic content was also investigated. RESULTS Totally 12 animal experiments and 9 clinical studies were included. Based on strong evidence, 4 phyla (Bacteroidetes, Fusobacteria, Verrucomicrobia and Proteobacteria) increased after surgery; within the phylum Firmicutes, Lactobacillales and Enterococcus increased; and within the phylum Proteobacteria, Gammaproteobacteria, Enterobacteriales Enterobacteriaceae and several genera and species increased. Decreased microbial groups were Firmicutes, Clostridiales, Clostridiaceae, Blautia and Dorea. However, the change in microbial diversity is still under debate. Faecalibacterium prausnitzii, Lactobacillus and Coprococcus comes are implicated in many of the outcomes, including body composition and glucose homeostasis. CONCLUSIONS There is strong evidence to support a considerable alteration of the gut microbiome after bariatric surgery. Deeper investigations are required to confirm the mechanisms that link the gut microbiome and metabolic alterations in human metabolism.
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Affiliation(s)
- Yan Guo
- Department of Endocrinology, Changhai Hospital, Shanghai, China
| | - Zhi-Ping Huang
- Third Department of Hepatic Surgery, Shanghai Eastern Hepatobiliary Surgery Hospital, Shanghai, China
- Department of General Surgery, Shangai Changhai Hospital, Shanghai, China
| | - Chao-Qian Liu
- Department of General Surgery, Shangai Changhai Hospital, Shanghai, China
| | - Lin Qi
- Department of Orthopaedics, the Second Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Yuan Sheng
- Department of General Surgery, Shangai Changhai Hospital, Shanghai, China
| | - Da-Jin Zou
- Department of Endocrinology, Changhai Hospital, Shanghai, China
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6
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Hall CL, Lee VT. Cyclic-di-GMP regulation of virulence in bacterial pathogens. WILEY INTERDISCIPLINARY REVIEWS. RNA 2018; 9:10.1002/wrna.1454. [PMID: 28990312 PMCID: PMC5739959 DOI: 10.1002/wrna.1454] [Citation(s) in RCA: 59] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2017] [Revised: 08/29/2017] [Accepted: 09/01/2017] [Indexed: 12/16/2022]
Abstract
Signaling pathways allow bacteria to adapt to changing environments. For pathogenic bacteria, signaling pathways allow for timely expression of virulence factors and the repression of antivirulence factors within the mammalian host. As the bacteria exit the mammalian host, signaling pathways enable the expression of factors promoting survival in the environment and/or nonmammalian hosts. One such signaling pathway uses the dinucleotide cyclic-di-GMP (c-di-GMP), and many bacterial genomes encode numerous proteins that are responsible for synthesizing and degrading c-di-GMP. Once made, c-di-GMP binds to individual protein and RNA receptors to allosterically alter the macromolecule function to drive phenotypic changes. Each bacterial genome encodes unique sets of genes for c-di-GMP signaling and virulence factors so the regulation by c-di-GMP is organism specific. Recent works have pointed to evidence that c-di-GMP regulates virulence in different bacterial pathogens of mammalian hosts. In this review, we discuss the criteria for determining the contribution of signaling nucleotides to pathogenesis using a well-characterized signaling nucleotide, cyclic AMP (cAMP), in Pseudomonas aeruginosa. Using these criteria, we review the roles of c-di-GMP in mediating virulence and highlight common themes that exist among eight diverse pathogens that cause different diseases through different routes of infection and transmission. WIREs RNA 2018, 9:e1454. doi: 10.1002/wrna.1454 This article is categorized under: RNA in Disease and Development > RNA in Disease.
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Affiliation(s)
- Cherisse L Hall
- Department of Cell Biology and Molecular Genetics, University of Maryland at College Park, College Park, MD, USA
| | - Vincent T Lee
- Department of Cell Biology and Molecular Genetics, University of Maryland at College Park, College Park, MD, USA
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7
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Parreira VR, Ojha S, Lepp D, Mehdizadeh Gohari I, Zhou H, Susta L, Gong J, Prescott JF. Necrotic enteritis locus 1 diguanylate cyclase and phosphodiesterase (cyclic-di-GMP) gene mutation attenuates virulence in an avian necrotic enteritis isolate of Clostridium perfringens. Vet Microbiol 2017; 208:69-73. [PMID: 28888651 DOI: 10.1016/j.vetmic.2017.07.012] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Revised: 07/12/2017] [Accepted: 07/12/2017] [Indexed: 11/29/2022]
Abstract
Necrotic enteritis (NE) caused by netB-positive strains of Clostridium perfringens is an important disease of intensively-reared broiler chickens. It is widely controlled by antibiotic use, but this practice that has come under increasing scrutiny and alternative approaches are required. As part of the search for alternative approaches over the last decade, advances have been made in understanding its pathogenesis but much remains to be understood and applied to the control of NE. The objective of this work was to assess the effect on virulence of mutation of the cyclic-di-GMP signaling genes present on the large pathogenicity locus (NELoc-1) in the tcp-encoding conjugative virulence plasmid, pNetB. For this purpose, the diguanylate cyclase (dgc) and phosphodiesterase (pde) genes were individually insertionally inactivated and the two mutants were subsequently complemented with their respective genes. Southern blotting showed that a single gene insertion was present. Mutation of either gene resulted in almost total attenuation of the mutants to cause NE in experimentally-infected broiler chickens, which was fully restored in each case by complementation of the respective mutated gene. Production of NetB-associated cytotoxicity for Leghorn male hepatoma (LMH) cells was unaffected in mutants. We conclude that the cyclic-di-GMP signaling system is important in controlling virulence in a NE C. perfringens strain and might be a target for control of the disease.
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Affiliation(s)
- Valeria R Parreira
- Department of Pathobiology, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - Shivani Ojha
- Department of Pathobiology, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - Dion Lepp
- Guelph Research and Development Centre, Agriculture and Agri-Food Canada, Guelph, Ontario N1G 5C9, Canada
| | | | - Hongzhuan Zhou
- Guelph Research and Development Centre, Agriculture and Agri-Food Canada, Guelph, Ontario N1G 5C9, Canada; Beijing Agro-Biotechnology Research Center, Beijing Academy of Agriculture and Forestry Sciences, Beijing, 100097 China
| | - Leonardo Susta
- Department of Pathobiology, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - Jianhua Gong
- Guelph Research and Development Centre, Agriculture and Agri-Food Canada, Guelph, Ontario N1G 5C9, Canada
| | - John F Prescott
- Department of Pathobiology, University of Guelph, Guelph, Ontario N1G 2W1, Canada.
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8
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Corver J, Cordo' V, van Leeuwen HC, Klychnikov OI, Hensbergen PJ. Covalent attachment and Pro-Pro endopeptidase (PPEP-1)-mediated release of Clostridium difficile cell surface proteins involved in adhesion. Mol Microbiol 2017. [PMID: 28636257 DOI: 10.1111/mmi.13736] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
In the past decade, Clostridium difficile has emerged as an important gut pathogen. This anaerobic, Gram-positive bacterium is the main cause of infectious nosocomial diarrhea. Whereas much is known about the mechanism through which the C. difficile toxins cause diarrhea, relatively little is known about the dynamics of adhesion and motility, which is mediated by cell surface proteins. This review will discuss the recent advances in our understanding of the sortase-mediated covalent attachment of cell surface (adhesion) proteins to the peptidoglycan layer of C. difficile and their release through the action of a highly specific secreted metalloprotease (Pro-Pro endopeptidase 1, PPEP-1). Specific emphasis will be on a model in which PPEP-1 and its substrates control the switch from a sessile to motile phenotype in C. difficile, and how this is regulated by the cyclic dinucleotide c-di-GMP (3'-5' cyclic dimeric guanosine monophosphate).
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Affiliation(s)
- Jeroen Corver
- Department of Medical Microbiology, Leiden University Medical Center, 2333 ZA Leiden, The Netherlands
| | - Valentina Cordo'
- Center for Proteomics and Metabolomics, Leiden University Medical Center, 2333 ZA Leiden, The Netherlands
| | - Hans C van Leeuwen
- Department of Medical Microbiology, Leiden University Medical Center, 2333 ZA Leiden, The Netherlands
| | - Oleg I Klychnikov
- Laboratory for Biocrystallography, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, 3000 Leuven, Belgium
| | - Paul J Hensbergen
- Center for Proteomics and Metabolomics, Leiden University Medical Center, 2333 ZA Leiden, The Netherlands
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9
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Anjuwon-Foster BR, Tamayo R. A genetic switch controls the production of flagella and toxins in Clostridium difficile. PLoS Genet 2017; 13:e1006701. [PMID: 28346491 PMCID: PMC5386303 DOI: 10.1371/journal.pgen.1006701] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2016] [Revised: 04/10/2017] [Accepted: 03/16/2017] [Indexed: 12/15/2022] Open
Abstract
In the human intestinal pathogen Clostridium difficile, flagella promote adherence to intestinal epithelial cells. Flagellar gene expression also indirectly impacts production of the glucosylating toxins, which are essential to diarrheal disease development. Thus, factors that regulate the expression of the flgB operon will likely impact toxin production in addition to flagellar motility. Here, we report the identification a "flagellar switch" that controls the phase variable production of flagella and glucosylating toxins. The flagellar switch, located upstream of the flgB operon containing the early stage flagellar genes, is a 154 bp invertible sequence flanked by 21 bp inverted repeats. Bacteria with the sequence in one orientation expressed flagellum and toxin genes, produced flagella, and secreted the toxins ("flg phase ON"). Bacteria with the sequence in the inverse orientation were attenuated for flagellar and toxin gene expression, were aflagellate, and showed decreased toxin secretion ("flg phase OFF"). The orientation of the flagellar switch is reversible during growth in vitro. We provide evidence that gene regulation via the flagellar switch occurs post-transcription initiation and requires a C. difficile-specific regulatory factor to destabilize or degrade the early flagellar gene mRNA when the flagellar switch is in the OFF orientation. Lastly, through mutagenesis and characterization of flagellar phase locked isolates, we determined that the tyrosine recombinase RecV, which catalyzes inversion at the cwpV switch, is also responsible for inversion at the flagellar switch in both directions. Phase variable flagellar motility and toxin production suggests that these important virulence factors have both advantageous and detrimental effects during the course of infection.
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Affiliation(s)
- Brandon R. Anjuwon-Foster
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, North Carolina, United States of America
| | - Rita Tamayo
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, North Carolina, United States of America
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10
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Pham TH, Liang ZX, Marcellin E, Turner MS. Replenishing the cyclic-di-AMP pool: regulation of diadenylate cyclase activity in bacteria. Curr Genet 2016; 62:731-738. [PMID: 27074767 DOI: 10.1007/s00294-016-0600-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2016] [Revised: 03/29/2016] [Accepted: 04/01/2016] [Indexed: 02/08/2023]
Abstract
Bacteria can sense environmental cues and alter their physiology accordingly through the use of signal transduction pathways involving second messenger nucleotides. One broadly conserved second messenger is cyclic-di-AMP (c-di-AMP) which regulates a range of processes including cell wall homeostasis, potassium uptake, DNA repair, fatty acid synthesis, biofilm formation and central metabolism in bacteria. The intracellular pool of c-di-AMP is maintained by the activities of diadenylate cyclase (DAC) and phosphodiesterase (PDE) enzymes, as well as possibly via c-di-AMP export. Whilst extracellular stimuli regulating c-di-AMP levels in bacteria are poorly understood, recent work has identified effector proteins which directly interact and alter the activity of DACs. These include the membrane bound CdaR and the phosphoglucosamine mutase GlmM which both bind directly to the membrane bound CdaA DAC and the recombination protein RadA which binds directly to the DNA binding DisA DAC. The genes encoding these multiprotein complexes are co-localised in many bacteria providing further support for their functional connection. The roles of GlmM in peptidoglycan synthesis and RadA in Holliday junction intermediate processing suggest that c-di-AMP synthesis by DACs will be responsive to these cellular activities. In addition to these modulatory interactions, permanent dysregulation of DAC activity due to suppressor mutations can occur during selection to overcome growth defects, rapid cell lysis and osmosensitivity. DACs have also been investigated as targets for the development of new antibiotics and several small compound inhibitors have recently been identified. This review aims to provide an overview of how c-di-AMP synthesis by DACs can be regulated.
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Affiliation(s)
- Thi Huong Pham
- School of Agriculture and Food Sciences, University of Queensland, Brisbane, QLD, Australia
| | - Zhao-Xun Liang
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
| | - Esteban Marcellin
- Australian Institute for Bioengineering and Nanotechnology, University of Queensland, Brisbane, QLD, Australia
| | - Mark S Turner
- School of Agriculture and Food Sciences, University of Queensland, Brisbane, QLD, Australia.
- Queensland Alliance for Agriculture and Food Innovation, University of Queensland, Brisbane, QLD, Australia.
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11
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Abt MC, McKenney PT, Pamer EG. Clostridium difficile colitis: pathogenesis and host defence. Nat Rev Microbiol 2016; 14:609-20. [PMID: 27573580 DOI: 10.1038/nrmicro.2016.108] [Citation(s) in RCA: 336] [Impact Index Per Article: 42.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Clostridium difficile is a major cause of intestinal infection and diarrhoea in individuals following antibiotic treatment. Recent studies have begun to elucidate the mechanisms that induce spore formation and germination and have determined the roles of C. difficile toxins in disease pathogenesis. Exciting progress has also been made in defining the role of the microbiome, specific commensal bacterial species and host immunity in defence against infection with C. difficile. This Review will summarize the recent discoveries and developments in our understanding of C. difficile infection and pathogenesis.
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Affiliation(s)
- Michael C Abt
- Immunology Program, Lucille Castori Center for Microbes, Inflammation and Cancer, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, New York 10065, USA
| | - Peter T McKenney
- Immunology Program, Lucille Castori Center for Microbes, Inflammation and Cancer, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, New York 10065, USA
| | - Eric G Pamer
- Immunology Program, Lucille Castori Center for Microbes, Inflammation and Cancer, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, New York 10065, USA
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12
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Abstract
Infection of the colon with the Gram-positive bacterium Clostridium difficile is potentially life threatening, especially in elderly people and in patients who have dysbiosis of the gut microbiota following antimicrobial drug exposure. C. difficile is the leading cause of health-care-associated infective diarrhoea. The life cycle of C. difficile is influenced by antimicrobial agents, the host immune system, and the host microbiota and its associated metabolites. The primary mediators of inflammation in C. difficile infection (CDI) are large clostridial toxins, toxin A (TcdA) and toxin B (TcdB), and, in some bacterial strains, the binary toxin CDT. The toxins trigger a complex cascade of host cellular responses to cause diarrhoea, inflammation and tissue necrosis - the major symptoms of CDI. The factors responsible for the epidemic of some C. difficile strains are poorly understood. Recurrent infections are common and can be debilitating. Toxin detection for diagnosis is important for accurate epidemiological study, and for optimal management and prevention strategies. Infections are commonly treated with specific antimicrobial agents, but faecal microbiota transplants have shown promise for recurrent infections. Future biotherapies for C. difficile infections are likely to involve defined combinations of key gut microbiota.
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Affiliation(s)
- Wiep Klaas Smits
- Section Experimental Bacteriology, Department of Medical Microbiology, Leiden University Medical Center, PO Box 9600, 2300 RC Leiden, The Netherlands
| | - Dena Lyras
- Infection and Immunity Program, Monash Biomedicine Discovery Institute, and Department of Microbiology, Monash University, Victoria, Australia
| | - D. Borden Lacy
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, and The Veterans Affairs Tennessee Valley Healthcare System, Nashville Tennessee, USA
| | - Mark H. Wilcox
- Institute of Biomedical and Clinical Sciences, University of Leeds, Leeds, UK
| | - Ed J. Kuijper
- Section Experimental Bacteriology, Department of Medical Microbiology, Leiden University Medical Center, PO Box 9600, 2300 RC Leiden, The Netherlands
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13
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Hensbergen PJ, Klychnikov OI, Bakker D, Dragan I, Kelly ML, Minton NP, Corver J, Kuijper EJ, Drijfhout JW, van Leeuwen HC. Clostridium difficile secreted Pro-Pro endopeptidase PPEP-1 (ZMP1/CD2830) modulates adhesion through cleavage of the collagen binding protein CD2831. FEBS Lett 2015; 589:3952-8. [PMID: 26522134 DOI: 10.1016/j.febslet.2015.10.027] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2015] [Revised: 10/12/2015] [Accepted: 10/19/2015] [Indexed: 02/04/2023]
Abstract
The Clostridium difficile cd2830 gene product is a secreted metalloprotease, named Pro-Pro endopeptidase (PPEP-1). PPEP-1 cleaves C. difficile cell surface proteins (e.g. CD2831). Here, we confirmed that PPEP-1 has a unique preference for prolines surrounding the scissile bond. Moreover, we show that it exhibits a high preference for an asparagine at the P2 position and hydrophobic residues at the P3 position. Using a PPEP-1 knockout C. difficile strain, we demonstrate that the removal of the collagen binding protein CD2831 is fully attributable to PPEP-1 activity. The PPEP-1 knockout strain demonstrated higher affinity for collagen type I with attenuated virulence in hamsters.
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Affiliation(s)
- Paul J Hensbergen
- Center for Proteomics and Metabolomics, Leiden University Medical Center, PO Box 9600, 2300RC Leiden, The Netherlands.
| | - Oleg I Klychnikov
- Center for Proteomics and Metabolomics, Leiden University Medical Center, PO Box 9600, 2300RC Leiden, The Netherlands
| | - Dennis Bakker
- Department of Medical Microbiology, Section Experimental Bacteriology, Leiden University Medical Center, PO Box 9600, 2300RC Leiden, The Netherlands
| | - Irina Dragan
- Center for Proteomics and Metabolomics, Leiden University Medical Center, PO Box 9600, 2300RC Leiden, The Netherlands
| | - Michelle L Kelly
- Clostridia Research Group, BBSRC/EPSRC Synthetic Biology Research Centre (SBRC), School of Life Sciences, The University of Nottingham, NG7 2RD, United Kingdom
| | - Nigel P Minton
- Clostridia Research Group, BBSRC/EPSRC Synthetic Biology Research Centre (SBRC), School of Life Sciences, The University of Nottingham, NG7 2RD, United Kingdom
| | - Jeroen Corver
- Department of Medical Microbiology, Section Experimental Bacteriology, Leiden University Medical Center, PO Box 9600, 2300RC Leiden, The Netherlands
| | - Ed J Kuijper
- Department of Medical Microbiology, Section Experimental Bacteriology, Leiden University Medical Center, PO Box 9600, 2300RC Leiden, The Netherlands
| | - Jan Wouter Drijfhout
- Department of Immunohematology and Blood Transfusion, Leiden University Medical Center, PO Box 9600, 2300RC Leiden, The Netherlands
| | - Hans C van Leeuwen
- Department of Medical Microbiology, Section Experimental Bacteriology, Leiden University Medical Center, PO Box 9600, 2300RC Leiden, The Netherlands.
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14
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Identification of ligands for bacterial sensor proteins. Curr Genet 2015; 62:143-7. [PMID: 26511375 DOI: 10.1007/s00294-015-0528-4] [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: 10/16/2015] [Revised: 10/19/2015] [Accepted: 10/20/2015] [Indexed: 10/22/2022]
Abstract
Bacteria have evolved a variety of different signal transduction mechanisms. However, the cognate signal molecule for the very large amount of corresponding sensor proteins is unknown and their functional annotation represents a major bottleneck in the field of signal transduction. The knowledge of the signal molecule is an essential prerequisite to understand the signalling mechanisms. Recently, the identification of signal molecules by the high-throughput protein screening of commercially available ligand collections using differential scanning fluorimetry has shown promise to resolve this bottleneck. Based on the analysis of a significant number of different ligand binding domains (LBDs) in our laboratory, we identified two issues that need to be taken into account in the experimental design. Since a number of LBDs require the dimeric state for ligand recognition, it has to be assured that the protein analysed is indeed in the dimeric form. A number of other examples demonstrate that purified LBDs can contain bound ligand which prevents further binding. In such cases, the apo-form can be generated by denaturation and subsequent refolding. We are convinced that this approach will accelerate the functional annotation of sensor proteins which will help to understand regulatory circuits in bacteria.
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Colton DM, Stabb EV. Rethinking the roles of CRP, cAMP, and sugar-mediated global regulation in the Vibrionaceae. Curr Genet 2015. [PMID: 26215147 DOI: 10.1007/s00294-015-0508-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Many proteobacteria modulate a suite of catabolic genes using the second messenger cyclic 3', 5'-AMP (cAMP) and the cAMP receptor protein (CRP). Together, the cAMP-CRP complex regulates target promoters, usually by activating transcription. In the canonical model, the phosphotransferase system (PTS), and in particular the EIIA(Glc) component for glucose uptake, provides a mechanistic link that modulates cAMP levels depending on glucose availability, resulting in more cAMP and activation of alternative catabolic pathways when glucose is unavailable. Within the Vibrionaceae, cAMP-CRP appears to play the classical role in modulating metabolic pathways; however, it also controls functions involved in natural competence, bioluminescence, pheromone signaling, and colonization of animal hosts. For this group of marine bacteria, chitin is an ecologically relevant resource, and chitin's monomeric sugar N-acetylglucosamine (NAG) supports robust growth while also triggering regulatory responses. Recent studies with Vibrio fischeri indicate that NAG and glucose uptake share EIIA(Glc), yet the responses of cAMP-CRP to these two carbon sources are starkly different. Moreover, control of cAMP levels appears to be more dominantly controlled by export and degradation. Perhaps more surprisingly, although CRP may require cAMP, its activity can be controlled in response to glucose by a mechanism independent of cAMP levels. Future studies in this area promise to shed new light on the role of cAMP and CRP.
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Affiliation(s)
- Deanna M Colton
- Department of Microbiology, University of Georgia, 120 Cedar Street, Athens, GA, 30602, USA
| | - Eric V Stabb
- Department of Microbiology, University of Georgia, 120 Cedar Street, Athens, GA, 30602, USA.
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