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Cyclic Di-GMP Regulates Multiple Cellular Functions in the Symbiotic Alphaproteobacterium Sinorhizobium meliloti. J Bacteriol 2015; 198:521-35. [PMID: 26574513 DOI: 10.1128/jb.00795-15] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2015] [Accepted: 11/09/2015] [Indexed: 12/14/2022] Open
Abstract
UNLABELLED Sinorhizobium meliloti undergoes major lifestyle changes between planktonic states, biofilm formation, and symbiosis with leguminous plant hosts. In many bacteria, the second messenger 3',5'-cyclic di-GMP (c-di-GMP, or cdG) promotes a sessile lifestyle by regulating a plethora of processes involved in biofilm formation, including motility and biosynthesis of exopolysaccharides (EPS). Here, we systematically investigated the role of cdG in S. meliloti Rm2011 encoding 22 proteins putatively associated with cdG synthesis, degradation, or binding. Single mutations in 21 of these genes did not cause evident changes in biofilm formation, motility, or EPS biosynthesis. In contrast, manipulation of cdG levels by overproducing endogenous or heterologous diguanylate cyclases (DGCs) or phosphodiesterases (PDEs) affected these processes and accumulation of N-Acyl-homoserine lactones in the culture supernatant. Specifically, individual overexpression of the S. meliloti genes pleD, SMb20523, SMb20447, SMc01464, and SMc03178 encoding putative DGCs and of SMb21517 encoding a single-domain PDE protein had an impact and resulted in increased levels of cdG. Compared to the wild type, an S. meliloti strain that did not produce detectable levels of cdG (cdG(0)) was more sensitive to acid stress. However, it was symbiotically potent, unaffected in motility, and only slightly reduced in biofilm formation. The SMc01790-SMc01796 locus, homologous to the Agrobacterium tumefaciens uppABCDEF cluster governing biosynthesis of a unipolarly localized polysaccharide, was found to be required for cdG-stimulated biofilm formation, while the single-domain PilZ protein McrA was identified as a cdG receptor protein involved in regulation of motility. IMPORTANCE We present the first systematic genome-wide investigation of the role of 3',5'-cyclic di-GMP (c-di-GMP, or cdG) in regulation of motility, biosynthesis of exopolysaccharides, biofilm formation, quorum sensing, and symbiosis in a symbiotic alpha-rhizobial species. Phenotypes of an S. meliloti strain unable to produce cdG (cdG(0)) demonstrated that this second messenger is not essential for root nodule symbiosis but may contribute to acid tolerance. Our data further suggest that enhanced levels of cdG promote sessility of S. meliloti and uncovered a single-domain PilZ protein as regulator of motility.
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Zheng C, Ma Y, Wang X, Xie Y, Ali MK, He J. Functional analysis of the sporulation-specific diadenylate cyclase CdaS in Bacillus thuringiensis. Front Microbiol 2015; 6:908. [PMID: 26441857 PMCID: PMC4568413 DOI: 10.3389/fmicb.2015.00908] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2015] [Accepted: 08/19/2015] [Indexed: 01/03/2023] Open
Abstract
Cyclic di-AMP (c-di-AMP) is a recently discovered bacterial secondary messenger molecule, which is associated with various physiological functions. In the genus Bacillus, the intracellular level and turnover of c-di-AMP are mainly regulated by three diadenylate cyclases (DACs), including DisA, CdaA and CdaS, and two c-di-AMP-specific phosphodiesterases (GdpP and PgpH). In this study, we demonstrated that CdaS protein from B. thuringiensis is a hexameric DAC protein that can convert ATP or ADP to c-di-AMP in vitro and the N-terminal YojJ domain is essential for the DAC activity. Based on the markerless gene knock-out method, we demonstrated that the transcription of cdaS was initiated by the sporulation-specific sigma factor σ(H) and the deletion of cdaS significantly delayed sporulation and parasporal crystal formation. These findings contrast with similar experiments conducted using B. subtilis, wherein transcription of its cdaS was initiated by the sigma factor σ(G). Deletion of all the three DAC genes from a single strain was unsuccessful, suggesting that c-di-AMP is an indispensable molecule in B. thuringiensis. Phylogenetic analysis indicated increased diversity of CdaS in the B. cereus and B. subtilis Bacillus subgroups. In summary, this study identifies important aspects in the regulation of c-di-AMP in the genus Bacillus.
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Affiliation(s)
- Cao Zheng
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University Wuhan, China
| | - Yang Ma
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University Wuhan, China
| | - Xun Wang
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University Wuhan, China
| | - Yuqun Xie
- Key Laboratory of Fermentation Engineering (Ministry of Education), College of Bioengineering, Hubei University of Technology Wuhan, China
| | - Maria K Ali
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University Wuhan, China
| | - Jin He
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University Wuhan, China
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Peltier J, Shaw HA, Couchman EC, Dawson LF, Yu L, Choudhary JS, Kaever V, Wren BW, Fairweather NF. Cyclic diGMP regulates production of sortase substrates of Clostridium difficile and their surface exposure through ZmpI protease-mediated cleavage. J Biol Chem 2015; 290:24453-69. [PMID: 26283789 PMCID: PMC4591827 DOI: 10.1074/jbc.m115.665091] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2015] [Indexed: 01/12/2023] Open
Abstract
In Gram-positive pathogens, surface proteins may be covalently anchored to the bacterial peptidoglycan by sortase, a cysteine transpeptidase enzyme. In contrast to other Gram-positive bacteria, only one single sortase enzyme, SrtB, is conserved between strains of Clostridium difficile. Sortase-mediated peptidase activity has been reported in vitro, and seven potential substrates have been identified. Here, we demonstrate the functionality of sortase in C. difficile. We identify two sortase-anchored proteins, the putative adhesins CD2831 and CD3246, and determine the cell wall anchor structure of CD2831. The C-terminal PPKTG sorting motif of CD2831 is cleaved between the threonine and glycine residues, and the carboxyl group of threonine is amide-linked to the side chain amino group of diaminopimelic acid within the peptidoglycan peptide stem. We show that CD2831 protein levels are elevated in the presence of high intracellular cyclic diGMP (c-diGMP) concentrations, in agreement with the control of CD2831 expression by a c-diGMP-dependent type II riboswitch. Low c-diGMP levels induce the release of CD2831 and presumably CD3246 from the surface of cells. This regulation is mediated by proteolytic cleavage of CD2831 and CD3246 by the zinc metalloprotease ZmpI, whose expression is controlled by a type I c-diGMP riboswitch. These data reveal a novel regulatory mechanism for expression of two sortase substrates by the secondary messenger c-diGMP, on which surface anchoring is dependent.
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Affiliation(s)
- Johann Peltier
- From the Department of Life Sciences, Center for Molecular Bacteriology and Infection, Imperial College London, London SW7 2AZ, United Kingdom
| | - Helen A Shaw
- From the Department of Life Sciences, Center for Molecular Bacteriology and Infection, Imperial College London, London SW7 2AZ, United Kingdom
| | - Edward C Couchman
- From the Department of Life Sciences, Center for Molecular Bacteriology and Infection, Imperial College London, London SW7 2AZ, United Kingdom
| | - Lisa F Dawson
- the Department of Pathogen Molecular Biology, London School of Hygiene and Tropical Medicine, London WC1E 7HT, United Kingdom
| | - Lu Yu
- the Wellcome Trust Sanger Institute, Hinxton CB10 1SA, United Kingdom, and
| | - Jyoti S Choudhary
- the Wellcome Trust Sanger Institute, Hinxton CB10 1SA, United Kingdom, and
| | - Volkhard Kaever
- the Research Core Unit Metabolomics, Hannover Medical School, Hannover D-30625, Germany
| | - Brendan W Wren
- the Department of Pathogen Molecular Biology, London School of Hygiene and Tropical Medicine, London WC1E 7HT, United Kingdom
| | - Neil F Fairweather
- From the Department of Life Sciences, Center for Molecular Bacteriology and Infection, Imperial College London, London SW7 2AZ, United Kingdom,
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Tang Q, Luo Y, Zheng C, Yin K, Ali MK, Li X, He J. Functional Analysis of a c-di-AMP-specific Phosphodiesterase MsPDE from Mycobacterium smegmatis. Int J Biol Sci 2015; 11:813-24. [PMID: 26078723 PMCID: PMC4466462 DOI: 10.7150/ijbs.11797] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2015] [Accepted: 05/04/2015] [Indexed: 12/21/2022] Open
Abstract
Cyclic di‑AMP (c-di-AMP) is a second signaling molecule involved in the regulation of bacterial physiological processes and interaction between pathogen and host. However, the regulatory network mediated by c-di-AMP in Mycobacterium remains obscure. In M. smegmatis, a diadenylate cyclase (DAC) was reported recently, but there is still no investigation on c-di-AMP phosphodiesterase (PDE). Here, we provide a systematic study on signaling mechanism of c-di-AMP PDE in M. smegmatis. Based on our enzymatic analysis, MsPDE (MSMEG_2630), which contained a DHH-DHHA1 domain, displayed a 200-fold higher hydrolytic efficiency (kcat/Km) to c-di-AMP than to c-di-GMP. MsPDE was capable of converting c-di-AMP to pApA and AMP, and hydrolyzing pApA to AMP. Site-directed mutations in DHH and DHHA1 revealed that DHH domain was critical for the phosphodiesterase activity. To explore the regulatory role of c-di-AMP in vivo, we constructed the mspde mutant (Δmspde) and found that deficiency of MsPDE significantly enhanced intracellular C12-C20 fatty acid accumulation. Deficiency of DAC in many bacteria results in cell death. However, we acquired the M. smegmatis strain with DAC gene disrupted (ΔmsdisA) by homologous recombination approach. Deletion of msdisA reduced bacterial C12-C20 fatty acids production but scarcely affected bacterial survival. We also provided evidences that superfluous c-di-AMP in M. smegmatis could lead to abnormal colonial morphology. Collectively, our results indicate that MsPDE is a functional c-di-AMP-specific phosphodiesterase both in vitro and in vivo. Our study also expands the regulatory network mediated by c-di-AMP in M. smegmatis.
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Affiliation(s)
- Qing Tang
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, Hubei 430070, PR China
| | - Yunchao Luo
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, Hubei 430070, PR China
| | - Cao Zheng
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, Hubei 430070, PR China
| | - Kang Yin
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, Hubei 430070, PR China
| | - Maria Kanwal Ali
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, Hubei 430070, PR China
| | - Xinfeng Li
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, Hubei 430070, PR China
| | - Jin He
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, Hubei 430070, PR China
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Underwood AJ, Zhang Y, Metzger DW, Bai G. Detection of cyclic di-AMP using a competitive ELISA with a unique pneumococcal cyclic di-AMP binding protein. J Microbiol Methods 2014; 107:58-62. [PMID: 25239824 DOI: 10.1016/j.mimet.2014.08.026] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2014] [Revised: 08/18/2014] [Accepted: 08/21/2014] [Indexed: 10/24/2022]
Abstract
Cyclic di-AMP (c-di-AMP) is a recently recognized bacterial signaling molecule. In this study, a competitive enzyme-linked immunosorbent assay (ELISA) for the quantification of c-di-AMP was developed using a novel pneumococcal c-di-AMP binding protein (CabP). With this method, c-di-AMP concentrations in biological samples can be quickly and accurately quantified.
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Affiliation(s)
- Adam J Underwood
- Center for Immunology and Microbial Disease, MC-151, Albany Medical College, Albany, NY 12208-3479, USA
| | - Yang Zhang
- Center for Immunology and Microbial Disease, MC-151, Albany Medical College, Albany, NY 12208-3479, USA
| | - Dennis W Metzger
- Center for Immunology and Microbial Disease, MC-151, Albany Medical College, Albany, NY 12208-3479, USA
| | - Guangchun Bai
- Center for Immunology and Microbial Disease, MC-151, Albany Medical College, Albany, NY 12208-3479, USA.
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Engl C, Waite CJ, McKenna JF, Bennett MH, Hamann T, Buck M. Chp8, a diguanylate cyclase from Pseudomonas syringae pv. Tomato DC3000, suppresses the pathogen-associated molecular pattern flagellin, increases extracellular polysaccharides, and promotes plant immune evasion. mBio 2014; 5:e01168-14. [PMID: 24846383 PMCID: PMC4030453 DOI: 10.1128/mbio.01168-14] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2014] [Accepted: 04/14/2014] [Indexed: 12/22/2022] Open
Abstract
UNLABELLED The bacterial plant pathogen Pseudomonas syringae causes disease in a wide range of plants. The associated decrease in crop yields results in economic losses and threatens global food security. Competition exists between the plant immune system and the pathogen, the basic principles of which can be applied to animal infection pathways. P. syringae uses a type III secretion system (T3SS) to deliver virulence factors into the plant that promote survival of the bacterium. The P. syringae T3SS is a product of the hypersensitive response and pathogenicity (hrp) and hypersensitive response and conserved (hrc) gene cluster, which is strictly controlled by the codependent enhancer-binding proteins HrpR and HrpS. Through a combination of bacterial gene regulation and phenotypic studies, plant infection assays, and plant hormone quantifications, we now report that Chp8 (i) is embedded in the Hrp regulon and expressed in response to plant signals and HrpRS, (ii) is a functional diguanylate cyclase, (iii) decreases the expression of the major pathogen-associated molecular pattern (PAMP) flagellin and increases extracellular polysaccharides (EPS), and (iv) impacts the salicylic acid/jasmonic acid hormonal immune response and disease progression. We propose that Chp8 expression dampens PAMP-triggered immunity during early plant infection. IMPORTANCE The global demand for food is projected to rise by 50% by 2030 and, as such, represents one of the major challenges of the 21st century, requiring improved crop management. Diseases caused by plant pathogens decrease crop yields, result in significant economic losses, and threaten global food security. Gaining mechanistic insights into the events at the plant-pathogen interface and employing this knowledge to make crops more resilient is one important strategy for improving crop management. Plant-pathogen interactions are characterized by the sophisticated interplay between plant immunity elicited upon pathogen recognition and immune evasion by the pathogen. Here, we identify Chp8 as a contributor to the major effort of the plant pathogen Pseudomonas syringae pv. tomato DC3000 to evade immune responses of the plant.
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Affiliation(s)
- Christoph Engl
- Department of Life Sciences, Imperial College London, London, United Kingdom;
| | - Christopher J Waite
- Department of Life Sciences, Imperial College London, London, United Kingdom
| | - Joseph F McKenna
- Department of Biological and Medical Sciences, Oxford Brookes University, Oxford, United Kingdom
| | - Mark H Bennett
- Department of Life Sciences, Imperial College London, London, United Kingdom
| | - Thorsten Hamann
- Department of Biology, Norwegian University of Science and Technology, Trondheim, Norway
| | - Martin Buck
- Department of Life Sciences, Imperial College London, London, United Kingdom;
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