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Malik A, Oludiran A, Poudel A, Alvarez OB, Woodward C, Purcell EB. RelQ-mediated alarmone signalling regulates growth, stress-induced biofilm formation and spore accumulation in Clostridioides difficile. MICROBIOLOGY (READING, ENGLAND) 2024; 170:001479. [PMID: 39028551 PMCID: PMC11317968 DOI: 10.1099/mic.0.001479] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2024] [Accepted: 07/01/2024] [Indexed: 07/20/2024]
Abstract
The bacterial stringent response (SR) is a conserved transcriptional reprogramming pathway mediated by the nucleotide signalling alarmones, (pp)pGpp. The SR has been implicated in antibiotic survival in Clostridioides difficile, a biofilm- and spore-forming pathogen that causes resilient, highly recurrent C. difficile infections. The role of the SR in other processes and the effectors by which it regulates C. difficile physiology are unknown. C. difficile RelQ is a clostridial alarmone synthetase. Deletion of relQ dysregulates C. difficile growth in unstressed conditions, affects susceptibility to antibiotic and oxidative stressors and drastically reduces biofilm formation. While wild-type C. difficile displays increased biofilm formation in the presence of sublethal stress, the ΔrelQ strain cannot upregulate biofilm production in response to stress. Deletion of relQ slows spore accumulation in planktonic cultures but accelerates it in biofilms. This work establishes biofilm formation and spore accumulation as alarmone-mediated processes in C. difficile and reveals the importance of RelQ in stress-induced biofilm regulation.
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Affiliation(s)
- Areej Malik
- Biomedical Sciences Program, Old Dominion University, Norfolk, Virginia, 23529, USA
- Department of Chemistry and Biochemistry, Old Dominion University, Norfolk, Virginia, 23529, USA
| | - Adenrele Oludiran
- Department of Chemistry and Biochemistry, Old Dominion University, Norfolk, Virginia, 23529, USA
| | - Asia Poudel
- Department of Chemistry and Biochemistry, Old Dominion University, Norfolk, Virginia, 23529, USA
| | - Orlando Berumen Alvarez
- Department of Chemistry and Biochemistry, Old Dominion University, Norfolk, Virginia, 23529, USA
| | - Charles Woodward
- Department of Chemistry and Biochemistry, Old Dominion University, Norfolk, Virginia, 23529, USA
| | - Erin B. Purcell
- Department of Chemistry and Biochemistry, Old Dominion University, Norfolk, Virginia, 23529, USA
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2
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Lin MM, Yang SS, Huang QY, Cui GH, Jia XF, Yang Y, Shi ZM, Ye H, Zhang XZ. Effect and mechanism of Qingre Huashi decoction on drug-resistant Helicobacter pylori. World J Gastroenterol 2024; 30:3086-3105. [PMID: 38983958 PMCID: PMC11230061 DOI: 10.3748/wjg.v30.i24.3086] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/25/2024] [Revised: 05/05/2024] [Accepted: 05/29/2024] [Indexed: 06/25/2024] Open
Abstract
BACKGROUND Helicobacter pylori (HP), the most common pathogenic microorganism in the stomach, can induce inflammatory reactions in the gastric mucosa, causing chronic gastritis and even gastric cancer. HP infection affects over 4.4 billion people globally, with a worldwide infection rate of up to 50%. The multidrug resistance of HP poses a serious challenge to eradication. It has been de-monstrated that compared to bismuth quadruple therapy, Qingre Huashi decoction (QHD) combined with triple therapy exhibits comparable eradication rates but with a lower incidence of adverse reactions; in addition, QHD can directly inhibit and kill HP in vitro. AIM To explore the effect and mechanism of QHD on clinically multidrug-resistant and strong biofilm-forming HP. METHODS In this study, 12 HP strains were isolated in vitro after biopsy during gastroscopy of HP-infected patients. In vitro, the minimum inhibitory concentration (MIC) values for clinical HP strains and biofilm quantification were determined through the E-test method and crystal violet staining, respectively. The most robust biofilm-forming strain of HP was selected, and QHD was evaluated for its inhibitory and bactericidal effects on the strain with strong biofilm formation. This assessment was performed using agar dilution, E-test, killing dynamics, and transmission electron microscopy (TEM). The study also explored the impact of QHD on antibiotic resistance in these HP strains with strong biofilm formation. Crystalline violet method, scanning electron microscopy, laser confocal scanning microscopy, and (p)ppGpp chromatographic identification were employed to evaluate the effect of QHD on biofilm in strong biofilm-forming HP strains. The effect of QHD on biofilm and efflux pump-related gene expression was evaluated by quantitative polymerase chain reaction. Non-targeted metabolomics with UHPLC-MS/MS was used to identify potential metabolic pathways and biomarkers which were different between the NC and QHD groups. RESULTS HP could form biofilms of different degrees in vitro, and the intensity of formation was associated with the drug resistance of the strain. QHD had strong bacteriostatic and bactericidal effects on HP, with MICs of 32-64 mg/mL. QHD could inhibit the biofilm formation of the strong biofilm-forming HP strains, disrupt the biofilm structure, lower the accumulation of (p)ppGpp, decrease the expression of biofilm-related genes including LuxS, Spot, glup (HP1174), NapA, and CagE, and reduce the expression of efflux pump-related genes such as HP0605, HP0971, HP1327, and HP1489. Based on metabolomic analysis, QHD induced oxidative stress in HP, enhanced metabolism, and potentially inhibited relevant signaling pathways by upregulating adenosine monophosphate (AMP), thereby affecting HP growth, metabolism, and protein synthesis. CONCLUSION QHD exerts bacteriostatic and bactericidal effects on HP, and reduces HP drug resistance by inhibiting HP biofilm formation, destroying its biofilm structure, inhibiting the expression of biofilm-related genes and efflux pump-related genes, enhancing HP metabolism, and activating AMP in HP.
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Affiliation(s)
- Miao-Miao Lin
- Department of Integrated Traditional Chinese and Western Medicine, Peking University First Hospital, Beijing 100034, China
- Institute of Integrated Traditional Chinese and Western Medicine, Peking University, Beijing 100034, China
| | - Shan-Shan Yang
- Department of Integrated Traditional Chinese and Western Medicine, Peking University First Hospital, Beijing 100034, China
- Institute of Integrated Traditional Chinese and Western Medicine, Peking University, Beijing 100034, China
| | - Qiu-Yue Huang
- Department of Integrated Traditional Chinese and Western Medicine, Peking University First Hospital, Beijing 100034, China
- Institute of Integrated Traditional Chinese and Western Medicine, Peking University, Beijing 100034, China
| | - Guang-Hui Cui
- Department of Integrated Traditional Chinese and Western Medicine, Peking University First Hospital, Beijing 100034, China
- Institute of Integrated Traditional Chinese and Western Medicine, Peking University, Beijing 100034, China
| | - Xiao-Fen Jia
- Department of Integrated Traditional Chinese and Western Medicine, Peking University First Hospital, Beijing 100034, China
- Institute of Integrated Traditional Chinese and Western Medicine, Peking University, Beijing 100034, China
| | - Yao Yang
- Department of Integrated Traditional Chinese and Western Medicine, Peking University First Hospital, Beijing 100034, China
- Institute of Integrated Traditional Chinese and Western Medicine, Peking University, Beijing 100034, China
| | - Zong-Ming Shi
- Department of Integrated Traditional Chinese and Western Medicine, Peking University First Hospital, Beijing 100034, China
- Institute of Integrated Traditional Chinese and Western Medicine, Peking University, Beijing 100034, China
| | - Hui Ye
- Department of Integrated Traditional Chinese and Western Medicine, Peking University First Hospital, Beijing 100034, China
- Institute of Integrated Traditional Chinese and Western Medicine, Peking University, Beijing 100034, China
| | - Xue-Zhi Zhang
- Department of Integrated Traditional Chinese and Western Medicine, Peking University First Hospital, Beijing 100034, China
- Institute of Integrated Traditional Chinese and Western Medicine, Peking University, Beijing 100034, China
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3
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Malik A, Oludiran A, Poudel A, Alvarez OB, Woodward C, Purcell EB. RelQ-mediated alarmone signaling regulates growth, sporulation, and stress-induced biofilm formation in Clostridioides difficile. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.14.580318. [PMID: 38405794 PMCID: PMC10888890 DOI: 10.1101/2024.02.14.580318] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/27/2024]
Abstract
The bacterial stringent response (SR) is a conserved transcriptional reprogramming pathway mediated by the nucleotide signaling alarmones, (pp)pGpp. The SR has been implicated in antibiotic survival in Clostridioides difficile, a biofilm- and spore-forming pathogen that causes resilient, highly recurrent C. difficile infections. The role of the SR in other processes and the effectors by which it regulates C. difficile physiology are unknown. C. difficile RelQ is a clostridial alarmone synthetase. Deletion of relQ dysregulates C. difficile growth in unstressed conditions, affects susceptibility to antibiotic and oxidative stressors, and drastically reduces biofilm formation. While wild-type C. difficile displays increased biofilm formation in the presence of sub-lethal stress, the ΔrelQ strain cannot upregulate biofilm production in response to stress. Deletion of relQ slows spore accumulation in planktonic cultures but accelerates it in biofilms. This work establishes biofilm formation and sporulation as alarmone-mediated processes in C. difficile and reveals the importance of RelQ in stress-induced biofilm regulation.
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Affiliation(s)
- Areej Malik
- Biomedical Sciences Program, Old Dominion University, Norfolk, Virginia, 23529, USA
- Department of Chemistry and Biochemistry, Old Dominion University, Norfolk, Virginia, 23529, USA
| | - Adenrele Oludiran
- Department of Chemistry and Biochemistry, Old Dominion University, Norfolk, Virginia, 23529, USA
| | - Asia Poudel
- Department of Chemistry and Biochemistry, Old Dominion University, Norfolk, Virginia, 23529, USA
| | - Orlando Berumen Alvarez
- Department of Chemistry and Biochemistry, Old Dominion University, Norfolk, Virginia, 23529, USA
| | - Charles Woodward
- Department of Chemistry and Biochemistry, Old Dominion University, Norfolk, Virginia, 23529, USA
| | - Erin B. Purcell
- Department of Chemistry and Biochemistry, Old Dominion University, Norfolk, Virginia, 23529, USA
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4
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Holban AM, Gregoire CM, Gestal MC. Conquering the host: Bordetella spp. and Pseudomonas aeruginosa molecular regulators in lung infection. Front Microbiol 2022; 13:983149. [PMID: 36225372 PMCID: PMC9549215 DOI: 10.3389/fmicb.2022.983149] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Accepted: 08/17/2022] [Indexed: 11/27/2022] Open
Abstract
When bacteria sense cues from the host environment, stress responses are activated. Two component systems, sigma factors, small RNAs, ppGpp stringent response, and chaperones start coordinate the expression of virulence factors or immunomodulators to allow bacteria to respond. Although, some of these are well studied, such as the two-component systems, the contribution of other regulators, such as sigma factors or ppGpp, is increasingly gaining attention. Pseudomonas aeruginosa is the gold standard pathogen for studying the molecular mechanisms to sense and respond to environmental cues. Bordetella spp., on the other hand, is a microbial model for studying host-pathogen interactions at the molecular level. These two pathogens have the ability to colonize the lungs of patients with chronic diseases, suggesting that they have the potential to share a niche and interact. However, the molecular networks that facilitate adaptation of Bordetella spp. to cues are unclear. Here, we offer a side-by-side comparison of what is known about these diverse molecular mechanisms that bacteria utilize to counteract host immune responses, while highlighting the relatively unexplored interactions between them.
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Affiliation(s)
- Alina M. Holban
- Research Institute of the University of Bucharest (ICUB), Bucharest, Romania
- Department of Microbiology and Immunology, Faculty of Biology, University of Bucharest, Bucharest, Romania
| | - Courtney M. Gregoire
- Department of Microbiology and Immunology, Louisiana State University Health Science Center, Shreveport, LA, United States
| | - Monica C. Gestal
- Department of Microbiology and Immunology, Louisiana State University Health Science Center, Shreveport, LA, United States
- *Correspondence: Monica C. Gestal, ;
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5
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Yin WL, Xie ZY, Zeng YH, Zhang J, Long H, Ren W, Zhang X, Cai XN, Huang AY. Two (p)ppGpp Synthetase Genes, relA and spoT, Are Involved in Regulating Cell Motility, Exopolysaccharides Production, and Biofilm Formation of Vibrio alginolyticus. Front Microbiol 2022; 13:858559. [PMID: 35422789 PMCID: PMC9002329 DOI: 10.3389/fmicb.2022.858559] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Accepted: 02/28/2022] [Indexed: 12/14/2022] Open
Abstract
The stringent response mediated by the signal molecule (p)ppGpp is involved in response to multiple environmental stresses and control of various physiological processes. Studies have revealed that (p)ppGpp strongly affects the formation and maintenance of several bacterial biofilms. However, the specific regulatory roles of (p)ppGpp in biofilms, especially in the expression of genes related to cell motility and exopolysaccharides (EPSs) production, remain poorly understood. We recently reported two (p)ppGpp synthetase genes relA and spoT from the epizootic pathogen Vibrio alginolyticus. Herein, we found that the (p)ppGpp synthetase genes of V. alginolyticus contributed to biofilm formation at low cell density and biofilm detachment at high cell density, respectively, in polystyrene microtiter plates. Quantitative reverse transcription PCR (qRT-PCR) analysis revealed that the expression levels of both EPSs and motility associated genes were consistent with the development of biofilms. Besides, the (p)ppGpp synthetase gene spoT was found to be closely involved in the regulation of flagellum, smooth/translucent colony morphology and spotty pellicle at the air-liquid interface. Interestingly, pleiotropic phenotypes of ΔrelAΔspoT were similar to that of the rpoN (σ54) deletion mutant. Meanwhile, the absence of (p)ppGpp synthetase genes significantly reduced the expression levels of rpoN at low cell density, suggesting that (p)ppGpp may mediate the formation via positively affecting the alternative sigma factor RpoN. These findings allow us to propose (p)ppGpp as a crucial regulator for biofilm development in V. alginolyticus, in view of the regulatory roles of relA and spoT in cell motility and EPSs production.
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Affiliation(s)
- Wen-Liang Yin
- State Key Laboratory of Marine Resource Utilization in the South China Sea, Hainan University, Haikou, China.,Laboratory of Development and Utilization of Marine Microbial Resource, Hainan University, Haikou, China.,College of Marine Sciences, Hainan University, Haikou, China
| | - Zhen-Yu Xie
- State Key Laboratory of Marine Resource Utilization in the South China Sea, Hainan University, Haikou, China.,Laboratory of Development and Utilization of Marine Microbial Resource, Hainan University, Haikou, China.,College of Marine Sciences, Hainan University, Haikou, China.,Key Laboratory of Tropical Hydrobiology and Biotechnology of Hainan Province, Haikou, China
| | - Yan-Hua Zeng
- State Key Laboratory of Marine Resource Utilization in the South China Sea, Hainan University, Haikou, China.,Laboratory of Development and Utilization of Marine Microbial Resource, Hainan University, Haikou, China
| | - Ju Zhang
- State Key Laboratory of Marine Resource Utilization in the South China Sea, Hainan University, Haikou, China.,Laboratory of Development and Utilization of Marine Microbial Resource, Hainan University, Haikou, China.,College of Marine Sciences, Hainan University, Haikou, China
| | - Hao Long
- State Key Laboratory of Marine Resource Utilization in the South China Sea, Hainan University, Haikou, China.,Laboratory of Development and Utilization of Marine Microbial Resource, Hainan University, Haikou, China
| | - Wei Ren
- State Key Laboratory of Marine Resource Utilization in the South China Sea, Hainan University, Haikou, China.,Laboratory of Development and Utilization of Marine Microbial Resource, Hainan University, Haikou, China.,College of Marine Sciences, Hainan University, Haikou, China.,Key Laboratory of Tropical Hydrobiology and Biotechnology of Hainan Province, Haikou, China
| | - Xiang Zhang
- State Key Laboratory of Marine Resource Utilization in the South China Sea, Hainan University, Haikou, China.,Laboratory of Development and Utilization of Marine Microbial Resource, Hainan University, Haikou, China.,College of Marine Sciences, Hainan University, Haikou, China.,Key Laboratory of Tropical Hydrobiology and Biotechnology of Hainan Province, Haikou, China
| | - Xiao-Ni Cai
- State Key Laboratory of Marine Resource Utilization in the South China Sea, Hainan University, Haikou, China.,Laboratory of Development and Utilization of Marine Microbial Resource, Hainan University, Haikou, China.,College of Marine Sciences, Hainan University, Haikou, China.,Key Laboratory of Tropical Hydrobiology and Biotechnology of Hainan Province, Haikou, China
| | - Ai-You Huang
- State Key Laboratory of Marine Resource Utilization in the South China Sea, Hainan University, Haikou, China.,Laboratory of Development and Utilization of Marine Microbial Resource, Hainan University, Haikou, China.,College of Marine Sciences, Hainan University, Haikou, China.,Key Laboratory of Tropical Hydrobiology and Biotechnology of Hainan Province, Haikou, China
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6
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In Mycobacterium abscessus, the stringent factor Rel regulates metabolism, but is not the only (p)ppGpp synthase. J Bacteriol 2021; 204:e0043421. [PMID: 34898264 DOI: 10.1128/jb.00434-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The stringent response is a broadly conserved stress response system that exhibits functional variability across bacterial clades. Here, we characterize the role of the stringent factor Rel in the non-tuberculous mycobacterial pathogen, Mycobacterium abscessus (Mab). We found that deletion of rel does not ablate (p)ppGpp synthesis, and that rel does not provide a survival advantage in several stress conditions, or in antibiotic treatment. Transcriptional data show that RelMab is involved in regulating expression of anabolism and growth genes in stationary phase. However, it does not activate transcription of stress response or antibiotic resistance genes, and actually represses transcription of many antibiotic resistance genes. This work shows that there is an unannotated (p)ppGpp synthetase in Mab. Importance In this study, we examined the functional roles of the stringent factor Rel in Mycobacterium abscessus (Mab). In most species, stringent factors synthesize the alarmone (p)ppGpp, which globally alters transcription to promote growth arrest and survival under stress and in antibiotic treatment. Our work shows that in Mab, an emerging pathogen which is resistant to many antibiotics, the stringent factor Rel is not solely responsible for synthesizing (p)ppGpp. We find that RelMab downregulates many metabolic genes under stress, but does not upregulate stress response genes and does not promote antibiotic tolerance. This study implies that there is another critical but unannotated (p)ppGpp synthetase in Mab, and suggests that RelMab inhibitors are unlikely to sensitize Mab infections to antibiotic treatment.
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SpoT-mediated NapA upregulation promotes oxidative stress-induced Helicobacter pylori biofilm formation and confers multidrug resistance. Antimicrob Agents Chemother 2021; 65:AAC.00152-21. [PMID: 33649116 PMCID: PMC8092859 DOI: 10.1128/aac.00152-21] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Recently, there is increased incidence of drug-resistant Helicobacter pylori infection. Biofilm formation confers multidrug resistance to bacteria. Moreover, it has been found that the formation of biofilm on the surface of gastric mucosa is an important reason for the difficulty of eradication of H. pylori The mechanisms underlying H. pylori biofilm formation in vivo have not been elucidated. Reactive oxygen species (ROS) released by the host immune cells in response to H. pylori infection cannot effectively clear the pathogen. Moreover, the extracellular matrix of the biofilm protects the bacteria against ROS-mediated toxicity. This study hypothesized that ROS can promote H. pylori biofilm formation and treatment with low concentrations of hydrogen peroxide (H2O2) promoted this process in vitro The comparative transcriptome analysis of planktonic and biofilm-forming cells revealed that the expression of SpoT, a (p)ppGpp (guanosine 3'-diphosphate 5'-triphosphate and guanosine 3',5'-bispyrophosphate) synthetase/hydrolase, is upregulated in H2O2-induced biofilms and that knockout of spoT inhibited H. pylori biofilm formation. Additionally, this study examined the key target molecules involved in SpoT regulation using weighted gene co-expression network analysis. The analysis revealed that neutrophil-activating protein (NapA; HP0243) promoted H2O2-induced biofilm formation and conferred multidrug resistance. Furthermore, vitamin C exhibited anti-H. pylori biofilm activity and downregulated the expression of napA in vitro These findings provide novel insight into the clearance of H. pylori biofilms.
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8
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Yin W, Xu S, Wang Y, Zhang Y, Chou SH, Galperin MY, He J. Ways to control harmful biofilms: prevention, inhibition, and eradication. Crit Rev Microbiol 2020; 47:57-78. [PMID: 33356690 DOI: 10.1080/1040841x.2020.1842325] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Biofilms are complex microbial architectures that encase microbial cells in a matrix comprising self-produced extracellular polymeric substances. Microorganisms living in biofilms are much more resistant to hostile environments than their planktonic counterparts and exhibit enhanced resistance against the microbicides. From the human perspective, biofilms can be classified into beneficial, neutral, and harmful. Harmful biofilms impact food safety, cause plant and animal diseases, and threaten medical fields, making it urgent to develop effective and robust strategies to control harmful biofilms. In this review, we discuss various strategies to control biofilm formation on infected tissues, implants, and medical devices. We classify the current strategies into three main categories: (i) changing the properties of susceptible surfaces to prevent biofilm formation; (ii) regulating signalling pathways to inhibit biofilm formation; (iii) applying external forces to eradicate the biofilm. We hope this review would motivate the development of innovative and effective strategies for controlling harmful biofilms.
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Affiliation(s)
- Wen Yin
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, PR China
| | - Siyang Xu
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, PR China
| | - Yiting Wang
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, PR China
| | - Yuling Zhang
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, PR China
| | - Shan-Ho Chou
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, PR China
| | - Michael Y Galperin
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD, USA
| | - Jin He
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, PR China
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9
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Irving SE, Choudhury NR, Corrigan RM. The stringent response and physiological roles of (pp)pGpp in bacteria. Nat Rev Microbiol 2020; 19:256-271. [PMID: 33149273 DOI: 10.1038/s41579-020-00470-y] [Citation(s) in RCA: 187] [Impact Index Per Article: 46.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/29/2020] [Indexed: 01/10/2023]
Abstract
The stringent response is a stress signalling system mediated by the alarmones guanosine tetraphosphate (ppGpp) and guanosine pentaphosphate (pppGpp) in response to nutrient deprivation. Recent research highlights the complexity and broad range of functions that these alarmones control. This Review provides an update on our current understanding of the enzymes involved in ppGpp, pppGpp and guanosine 5'-monophosphate 3'-diphosphate (pGpp) (collectively (pp)pGpp) turnover, including those shown to produce pGpp and its analogue (pp)pApp. We describe the well-known interactions with RNA polymerase as well as a broader range of cellular target pathways controlled by (pp)pGpp, including DNA replication, transcription, nucleotide synthesis, ribosome biogenesis and function, as well as lipid metabolism. Finally, we review the role of ppGpp and pppGpp in bacterial pathogenesis, providing examples of how these nucleotides are involved in regulating many aspects of virulence and chronic infection.
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Affiliation(s)
- Sophie E Irving
- The Florey Institute, Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield, UK
| | - Naznin R Choudhury
- The Florey Institute, Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield, UK
| | - Rebecca M Corrigan
- The Florey Institute, Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield, UK.
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10
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Salzer A, Keinhörster D, Kästle C, Kästle B, Wolz C. Small Alarmone Synthetases RelP and RelQ of Staphylococcus aureus Are Involved in Biofilm Formation and Maintenance Under Cell Wall Stress Conditions. Front Microbiol 2020; 11:575882. [PMID: 33072039 PMCID: PMC7533549 DOI: 10.3389/fmicb.2020.575882] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Accepted: 08/25/2020] [Indexed: 12/15/2022] Open
Abstract
The stringent response is characterized by the synthesis of the alarmone (p)ppGpp. The phenotypic consequences resulting from (p)ppGpp accumulation vary among species, and for several pathogenic bacteria, it has been shown that the activation of the stringent response strongly affects biofilm formation and maintenance. In Staphylococcus aureus, (p)ppGpp can be synthesized by the RelA/SpoT homolog Rel upon amino acid deprivation or by the two small alarmone synthetases RelP and RelQ under cell wall stress. We found that relP and relQ increase biofilm formation under cell wall stress conditions induced by a subinhibitory vancomycin concentration. However, the effect of (p)ppGpp on biofilm formation is independent of the regulators CodY and Agr. Biofilms formed by the strain HG001 or its (p)ppGpp-defective mutants are mainly composed of extracellular DNA and proteins. Furthermore, the induction of the RelPQ-mediated stringent response contributes to biofilm-related antibiotic tolerance. The proposed (p)ppGpp-inhibiting peptide DJK-5 shows bactericidal and biofilm-inhibitory activity. However, a non-(p)ppGpp-producing strain is even more vulnerable to DJK-5. This strongly argues against the assumption that DJK-5 acts via (p)ppGpp inhibition. In summary, RelP and RelQ play a major role in biofilm formation and maintenance under cell wall stress conditions.
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Affiliation(s)
| | | | | | | | - Christiane Wolz
- Interfaculty Institute of Microbiology and Infection Medicine, University of Tübingen, Tübingen, Germany
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11
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Kumar J, Chauhan AS, Shah RL, Gupta JA, Rathore AS. Amino acid supplementation for enhancing recombinant protein production in
E. coli. Biotechnol Bioeng 2020; 117:2420-2433. [DOI: 10.1002/bit.27371] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2020] [Accepted: 05/03/2020] [Indexed: 12/19/2022]
Affiliation(s)
- Jashwant Kumar
- Department of Chemical EngineeringIndian Institute of TechnologyNew Delhi India
| | - Ashish S. Chauhan
- Department of Chemical EngineeringIndian Institute of TechnologyNew Delhi India
| | - Rohan L. Shah
- Department of Chemical EngineeringIndian Institute of TechnologyNew Delhi India
| | - Jaya A. Gupta
- Department of Chemical EngineeringIndian Institute of TechnologyNew Delhi India
| | - Anurag S. Rathore
- Department of Chemical EngineeringIndian Institute of TechnologyNew Delhi India
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12
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Pletzer D, Sun E, Ritchie C, Wilkinson L, Liu LT, Trimble MJ, Wolfmeier H, Blimkie TM, Hancock REW. Surfing motility is a complex adaptation dependent on the stringent stress response in Pseudomonas aeruginosa LESB58. PLoS Pathog 2020; 16:e1008444. [PMID: 32208458 PMCID: PMC7122816 DOI: 10.1371/journal.ppat.1008444] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2019] [Revised: 04/03/2020] [Accepted: 02/29/2020] [Indexed: 11/18/2022] Open
Abstract
Cystic fibrosis (CF) is a genetic disease that affects mucin-producing body organs such as the lungs. Characteristic of CF is the production of thick, viscous mucus, containing the glycoprotein mucin, that can lead to progressive airway obstruction. Recently, we demonstrated that the presence of mucin induced a rapid surface adaptation in motile bacteria termed surfing motility, which data presented here indicates is very different from swarming motility. Pseudomonas aeruginosa, the main colonizing pathogen in CF, employs several stress coping mechanisms to survive the highly viscous environment of the CF lung. We used motility-based assays and RNA-Seq to study the stringent stress response in the hypervirulent CF isolate LESB58 (Liverpool Epidemic Strain). Motility experiments revealed that an LESB58 stringent response mutant (ΔrelAΔspoT) was unable to surf. Transcriptional profiling of ΔrelAΔspoT mutant cells from surfing agar plates, when compared to wild-type cells from the surfing edge, revealed 2,584 dysregulated genes. Gene Ontology and KEGG enrichment analysis revealed effects of the stringent response on amino acid, nucleic acid and fatty acid metabolism, TCA cycle and glycolysis, type VI secretion, as well as chemotaxis, cell communication, iron transport, nitrogen metabolic processes and cyclic-di-GMP signalling. Screening of the ordered PA14 transposon library revealed 224 mutants unable to surf and very limited overlap with genes required for swarming. Mutants affecting surfing included two downstream effector genes of the stringent stress response, the copper regulator cueR and the quinolone synthase pqsH. Both the cueR and pqsH cloned genes complemented the surfing deficiency of ΔrelAΔspoT. Our study revealed insights into stringent stress dependency in LESB58 and showed that surfing motility is stringently-controlled via the expression of cueR and pqsH. Downstream factors of the stringent stress response are important to investigate in order to fully understand its ability to colonize and persist in the CF lung.
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Affiliation(s)
- Daniel Pletzer
- Centre for Microbial Diseases and Immunity Research, Department of Microbiology and Immunology, University of British Columbia, Vancouver, Canada
- Department of Microbiology and Immunology, University of Otago, Dunedin, New Zealand
- * E-mail: (DP); (REWH)
| | - Evelyn Sun
- Centre for Microbial Diseases and Immunity Research, Department of Microbiology and Immunology, University of British Columbia, Vancouver, Canada
| | - Caleb Ritchie
- Centre for Microbial Diseases and Immunity Research, Department of Microbiology and Immunology, University of British Columbia, Vancouver, Canada
| | - Lauren Wilkinson
- Centre for Microbial Diseases and Immunity Research, Department of Microbiology and Immunology, University of British Columbia, Vancouver, Canada
| | - Leo T. Liu
- Centre for Microbial Diseases and Immunity Research, Department of Microbiology and Immunology, University of British Columbia, Vancouver, Canada
| | - Michael J. Trimble
- Centre for Microbial Diseases and Immunity Research, Department of Microbiology and Immunology, University of British Columbia, Vancouver, Canada
| | - Heidi Wolfmeier
- Centre for Microbial Diseases and Immunity Research, Department of Microbiology and Immunology, University of British Columbia, Vancouver, Canada
| | - Travis M. Blimkie
- Centre for Microbial Diseases and Immunity Research, Department of Microbiology and Immunology, University of British Columbia, Vancouver, Canada
| | - Robert E. W. Hancock
- Centre for Microbial Diseases and Immunity Research, Department of Microbiology and Immunology, University of British Columbia, Vancouver, Canada
- * E-mail: (DP); (REWH)
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13
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Bifunctional Enzyme SpoT Is Involved in Biofilm Formation of Helicobacter pylori with Multidrug Resistance by Upregulating Efflux Pump Hp1174 ( gluP). Antimicrob Agents Chemother 2018; 62:AAC.00957-18. [PMID: 30181372 PMCID: PMC6201075 DOI: 10.1128/aac.00957-18] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Accepted: 08/22/2018] [Indexed: 02/06/2023] Open
Abstract
The drug resistance of Helicobacter pylori is gradually becoming a serious problem. Biofilm formation is an important factor that leads to multidrug resistance (MDR) in bacteria. The drug resistance of Helicobacter pylori is gradually becoming a serious problem. Biofilm formation is an important factor that leads to multidrug resistance (MDR) in bacteria. The ability of H. pylori to form biofilms on the gastric mucosa is known. However, there are few studies on the regulatory mechanisms of H. pylori biofilm formation and multidrug resistance. Guanosine 3′-diphosphate 5′-triphosphate and guanosine 3′,5′-bispyrophosphate [(p)ppGpp] are global regulatory factors and are synthesized in H. pylori by the bifunctional enzyme SpoT. It has been reported that (p)ppGpp is involved in the biofilm formation and multidrug resistance of various bacteria. In this study, we found that SpoT also plays an important role in H. pylori biofilm formation and multidrug resistance. Therefore, it was necessary to carry out some further studies regarding its regulatory mechanism. Considering that efflux pumps are of great importance in the biofilm formation and multidrug resistance of bacteria, we tried to determine whether efflux pumps controlled by SpoT participate in these activities. We found that Hp1174 (glucose/galactose transporter [gluP]), an efflux pump of the major facilitator superfamily (MFS), is highly expressed in biofilm-forming and multidrug-resistant (MDR) H. pylori strains and is upregulated by SpoT. Through further research, we determined that gluP is involved in H. pylori biofilm formation and multidrug resistance. Furthermore, the average expression level of gluP in the clinical MDR strains (C-MDR) was considerably higher than that in the clinical drug-sensitive strains (C-DSS). Taken together, our results revealed a novel molecular mechanism of H. pylori resistance to multidrug exposure.
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Berne C, Ellison CK, Ducret A, Brun YV. Bacterial adhesion at the single-cell level. Nat Rev Microbiol 2018; 16:616-627. [DOI: 10.1038/s41579-018-0057-5] [Citation(s) in RCA: 266] [Impact Index Per Article: 44.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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15
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Kim HY, Go J, Lee KM, Oh YT, Yoon SS. Guanosine tetra- and pentaphosphate increase antibiotic tolerance by reducing reactive oxygen species production in Vibrio cholerae. J Biol Chem 2018; 293:5679-5694. [PMID: 29475943 PMCID: PMC5900777 DOI: 10.1074/jbc.ra117.000383] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2017] [Revised: 02/16/2018] [Indexed: 02/06/2023] Open
Abstract
The pathogen Vibrio cholerae is the causative agent of cholera. Emergence of antibiotic-resistant V. cholerae strains is increasing, but the underlying mechanisms remain unclear. Herein, we report that the stringent response regulator and stress alarmone guanosine tetra- and pentaphosphate ((p)ppGpp) significantly contributes to antibiotic tolerance in V. cholerae We found that N16961, a pandemic V. cholerae strain, and its isogenic (p)ppGpp-overexpressing mutant ΔrelAΔspoT are both more antibiotic-resistant than (p)ppGpp0 (ΔrelAΔrelVΔspoT) and ΔdksA mutants, which cannot produce or utilize (p)ppGpp, respectively. We also found that additional disruption of the aconitase B-encoding and tricarboxylic acid (TCA) cycle gene acnB in the (p)ppGpp0 mutant increases its antibiotic tolerance. Moreover, expression of TCA cycle genes, including acnB, was increased in (p)ppGpp0, but not in the antibiotic-resistant ΔrelAΔspoT mutant, suggesting that (p)ppGpp suppresses TCA cycle activity, thereby entailing antibiotic resistance. Importantly, when grown anaerobically or incubated with an iron chelator, the (p)ppGpp0 mutant became antibiotic-tolerant, suggesting that reactive oxygen species (ROS) are involved in antibiotic-mediated bacterial killing. Consistent with that hypothesis, tetracycline treatment markedly increased ROS production in the antibiotic-susceptible mutants. Interestingly, expression of the Fe(III) ABC transporter substrate-binding protein FbpA was increased 10-fold in (p)ppGpp0, and fbpA gene deletion restored viability of tetracycline-exposed (p)ppGpp0 cells. Of note, FbpA expression was repressed in the (p)ppGpp-accumulating mutant, resulting in a reduction of intracellular free iron, required for the ROS-generating Fenton reaction. Our results indicate that (p)ppGpp-mediated suppression of central metabolism and iron uptake reduces antibiotic-induced oxidative stress in V. cholerae.
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Affiliation(s)
- Hwa Young Kim
- From the Department of Microbiology and Immunology, Brain Korea 21 PLUS Project for Medical Science, and ,the Institute for Immunology and Immunological Diseases, Yonsei University College of Medicine, Seoul 03722, Korea and
| | - Junhyeok Go
- From the Department of Microbiology and Immunology, Brain Korea 21 PLUS Project for Medical Science, and ,the Institute for Immunology and Immunological Diseases, Yonsei University College of Medicine, Seoul 03722, Korea and
| | - Kang-Mu Lee
- From the Department of Microbiology and Immunology, Brain Korea 21 PLUS Project for Medical Science, and ,the Institute for Immunology and Immunological Diseases, Yonsei University College of Medicine, Seoul 03722, Korea and
| | - Young Taek Oh
- From the Department of Microbiology and Immunology, Brain Korea 21 PLUS Project for Medical Science, and ,the Freshwater Bioresources Utilization Division, Nakdonggang National Institute of Biological Resources, SangJu 37242, Korea, To whom correspondence may be addressed:
Freshwater Bioresources Utilization Division, Nakdonggang National Institute of Biological Resources, SangJu-si 37242, Korea. Tel.:
82-54-530-0932; Fax:
82-54-530-0949; E-mail:
| | - Sang Sun Yoon
- From the Department of Microbiology and Immunology, Brain Korea 21 PLUS Project for Medical Science, and ,the Institute for Immunology and Immunological Diseases, Yonsei University College of Medicine, Seoul 03722, Korea and , To whom correspondence may be addressed:
Dept. of Microbiology and Immunology, Yonsei University College of Medicine, 250 Seongsanno, Seodaemun-gu Seoul 120-752, Korea. Tel.:
82-2-2228-1824; Fax:
82-2-392-7088; E-mail:
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16
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Liu H, Xiao Y, Nie H, Huang Q, Chen W. Influence of (p)ppGpp on biofilm regulation in Pseudomonas putida KT2440. Microbiol Res 2017; 204:1-8. [PMID: 28870288 DOI: 10.1016/j.micres.2017.07.003] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2016] [Revised: 06/28/2017] [Accepted: 07/05/2017] [Indexed: 12/21/2022]
Abstract
The global regulatory molecule (p)ppGpp is synthesized under limited nutrition conditions and involves in many cellular processes in bacteria. (p)ppGpp has been reported to affect biofilm formation in several bacterial species. Here, we found that deletion of (p)ppGpp synthase genes of Pseudomonas putida KT2440 led to enhanced biofilm formation in polystyrene microtitre plates. Besides, the pellicle of this mutant formed at the air-liquid interface lost the robust structure and became frail. The biofilm formation and its structure are mainly determined by exopolysaccharides (EPSs) and adhesins. Transcriptional analysis of four EPS operons designated as pea, peb, alg and bcs and two adhesin genes nominated as lapA and lapF showed that the deletion of (p)ppGpp synthase genes increased the expression of peb, bcs and lapA but repressed the expression of pea and lapF. Furthermore, expression of the regulation factor FleQ was significantly augmented in (p)ppGpp-synthase mutants while the expression of sigma factor RpoS was reduced. Since FleQ and RpoS play important roles in regulating expression of EPS and adhesin genes, (p)ppGpp may mediate the synthesis of biofilm matrix via influencing these regulators to control the biofilm formation and pellicle structure.
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Affiliation(s)
- Huizhong Liu
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, China
| | - Yujie Xiao
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, China
| | - Hailing Nie
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, China
| | - Qiaoyun Huang
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, China; Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtze River), Ministry of Agriculture, College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China
| | - Wenli Chen
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, China.
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17
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Pseudomonas aeruginosa cells attached to a surface display a typical proteome early as 20 minutes of incubation. PLoS One 2017; 12:e0180341. [PMID: 28678862 PMCID: PMC5498041 DOI: 10.1371/journal.pone.0180341] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2017] [Accepted: 06/14/2017] [Indexed: 12/21/2022] Open
Abstract
Biofilms are present in all environments and often result in negative effects due to properties of the biofilm lifestyle and especially antibiotics resistance. Biofilms are associated with chronic infections. Controlling bacterial attachment, the first step of biofilm formation, is crucial for fighting against biofilm and subsequently preventing the persistence of infection. Thus deciphering the underlying molecular mechanisms involved in attachment could allow discovering molecular targets from it would be possible to develop inhibitors against bacterial colonization and potentiate antibiotherapy. To identify the key components and pathways that aid the opportunistic pathogen Pseudomonas aeruginosa in attachment we performed for the first time a proteomic analysis as early as after 20 minutes of incubation using glass wool fibers as a surface. We compared the protein contents of the attached and unattached bacteria. Using mass spectrometry, 3043 proteins were identified. Our results showed that, as of 20 minutes of incubation, using stringent quantification criteria 616 proteins presented a modification of their abundance in the attached cells compared to their unattached counterparts. The attached cells presented an overall reduced gene expression and characteristics of slow-growing cells. The over-accumulation of outer membrane proteins, periplasmic folding proteins and O-antigen chain length regulators was also observed, indicating a profound modification of the cell envelope. Consistently the sigma factor AlgU required for cell envelope homeostasis was highly over-accumulated in attached cells. In addition our data suggested a role of alarmone (p)ppGpp and polyphosphate during the early attachment phase. Furthermore, almost 150 proteins of unknown function were differentially accumulated in the attached cells. Our proteomic analysis revealed the existence of distinctive biological features in attached cells as early as 20 minutes of incubation. Analysis of some mutants demonstrated the interest of this proteomic approach in identifying genes involved in the early phase of adhesion to a surface.
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18
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D-methionine interferes with non-typeable Haemophilus influenzae peptidoglycan synthesis during growth and biofilm formation. Microbiology (Reading) 2017; 163:1093-1104. [DOI: 10.1099/mic.0.000491] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
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19
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Hoffman C, Eby J, Gray M, Heath Damron F, Melvin J, Cotter P, Hewlett E. Bordetella adenylate cyclase toxin interacts with filamentous haemagglutinin to inhibit biofilm formation in vitro. Mol Microbiol 2016; 103:214-228. [PMID: 27731909 DOI: 10.1111/mmi.13551] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/06/2016] [Indexed: 12/19/2022]
Abstract
Bordetella pertussis, the causative agent of whooping cough, secretes and releases adenylate cyclase toxin (ACT), which is a protein bacterial toxin that targets host cells and disarms immune defenses. ACT binds filamentous haemagglutinin (FHA), a surface-displayed adhesin, and until now, the consequences of this interaction were unknown. A B. bronchiseptica mutant lacking ACT produced more biofilm than the parental strain; leading Irie et al. to propose the ACT-FHA interaction could be responsible for biofilm inhibition. Here we characterize the physical interaction of ACT with FHA and provide evidence linking that interaction to inhibition of biofilm in vitro. Exogenous ACT inhibits biofilm formation in a concentration-dependent manner and the N-terminal catalytic domain of ACT (AC domain) is necessary and sufficient for this inhibitory effect. AC Domain interacts with the C-terminal segment of FHA with ∼650 nM affinity. ACT does not inhibit biofilm formation by Bordetella lacking the mature C-terminal domain (MCD), suggesting the direct interaction between AC domain and the MCD is required for the inhibitory effect. Additionally, AC domain disrupts preformed biofilm on abiotic surfaces. The demonstrated inhibition of biofilm formation by a host-directed protein bacterial toxin represents a novel regulatory mechanism and identifies an unprecedented role for ACT.
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Affiliation(s)
- Casandra Hoffman
- Division of Infectious Diseases and International Health, Department of Medicine, University of Virginia, Charlottesville, VA, USA
| | - Joshua Eby
- Division of Infectious Diseases and International Health, Department of Medicine, University of Virginia, Charlottesville, VA, USA
| | - Mary Gray
- Division of Infectious Diseases and International Health, Department of Medicine, University of Virginia, Charlottesville, VA, USA
| | - F Heath Damron
- Department of Microbiology, Immunology and Cell Biology, School of Medicine, West Virginia University, Morgantown, WV, USA
| | - Jeffrey Melvin
- School of Medicine, University of North Carolina, Chapel Hill, NC, USA
| | - Peggy Cotter
- School of Medicine, University of North Carolina, Chapel Hill, NC, USA
| | - Erik Hewlett
- Division of Infectious Diseases and International Health, Department of Medicine, University of Virginia, Charlottesville, VA, USA
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20
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Dorji D, Graham RM, Richmond P, Keil A, Mukkur TK. Biofilm forming potential and antimicrobial susceptibility of newly emerged Western Australian Bordetella pertussis clinical isolates. BIOFOULING 2016; 32:1141-1152. [PMID: 27669900 DOI: 10.1080/08927014.2016.1232715] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2015] [Accepted: 08/30/2016] [Indexed: 05/23/2023]
Abstract
Whooping cough caused by Bordetella pertussis is increasing in several countries despite high vaccine coverage. One potential reason for the resurgence is the emergence of genetic variants of the bacterium. Biofilm formation has recently been associated with the pathogenesis of B. pertussis. Biofilm formation of 21 Western Australian B. pertussis clinical isolates was investigated. All isolates formed thicker biofilms than the reference vaccine strain Tohama I while retaining susceptibility to ampicillin, erythromycin, azithromycin and streptomycin. When two biofilm-forming clinical isolates were compared with Tohama I, minimum bactericidal concentrations of antimicrobial agents increased. Isobaric tags for relative and absolute quantitation (iTRAQ)-based proteomic analysis revealed significant differences in protein expression in B. pertussis biofilms, providing an opportunity for identification of novel biofilm-associated antigens for incorporation in current pertussis vaccines to improve their protective efficacy. The study also highlights the importance of determining antibiograms for biofilms to formulate improved antimicrobial therapeutic regimens.
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Affiliation(s)
- Dorji Dorji
- a School of Biomedical Sciences and Curtin Health Innovation Research Institute (CHIRI) , Curtin University , Perth , Australia
- c Jigme Dorji Wangchuck National Referral Hospital , Khesar Gyalpo University of Medical Sciences of Bhutan , Thimphu , Bhutan
| | - Ross M Graham
- a School of Biomedical Sciences and Curtin Health Innovation Research Institute (CHIRI) , Curtin University , Perth , Australia
| | | | - Anthony Keil
- b Princess Margaret Hospital , Perth , Australia
| | - Trilochan K Mukkur
- a School of Biomedical Sciences and Curtin Health Innovation Research Institute (CHIRI) , Curtin University , Perth , Australia
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21
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Purcell EB, Tamayo R. Cyclic diguanylate signaling in Gram-positive bacteria. FEMS Microbiol Rev 2016; 40:753-73. [PMID: 27354347 DOI: 10.1093/femsre/fuw013] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/19/2016] [Indexed: 12/14/2022] Open
Abstract
The nucleotide second messenger 3'-5' cyclic diguanylate monophosphate (c-di-GMP) is a central regulator of the transition between motile and non-motile lifestyles in bacteria, favoring sessility. Most research investigating the functions of c-di-GMP has focused on Gram-negative species, especially pathogens. Recent work in Gram-positive species has revealed that c-di-GMP plays similar roles in Gram-positives, though the precise targets and mechanisms of regulation may differ. The majority of bacterial life exists in a surface-associated state, with motility allowing bacteria to disseminate and colonize new environments. c-di-GMP signaling regulates flagellum biosynthesis and production of adherence factors and appears to be a primary mechanism by which bacteria sense and respond to surfaces. Ultimately, c-di-GMP influences the ability of a bacterium to alter its transcriptional program, physiology and behavior upon surface contact. This review discusses how bacteria are able to sense a surface via flagella and type IV pili, and the role of c-di-GMP in regulating the response to surfaces, with emphasis on studies of Gram-positive bacteria.
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Affiliation(s)
- Erin B Purcell
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Rita Tamayo
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
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22
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Bacterial Metabolism in the Host Environment: Pathogen Growth and Nutrient Assimilation in the Mammalian Upper Respiratory Tract. Microbiol Spectr 2016; 3. [PMID: 26185081 DOI: 10.1128/microbiolspec.mbp-0007-2014] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Pathogens evolve in specific host niches and microenvironments that provide the physical and nutritional requirements conducive to their growth. In addition to using the host as a source of food, bacterial pathogens must avoid the immune response to their presence. The mammalian upper respiratory tract is a site that is exposed to the external environment, and is readily colonized by bacteria that live as resident flora or as pathogens. These bacteria can remain localized, descend to the lower respiratory tract, or traverse the epithelium to disseminate throughout the body. By virtue of their successful colonization of the respiratory epithelium, these bacteria obtain the nutrients needed for growth, either directly from host resources or from other microbes. This chapter describes the upper respiratory tract environment, including its tissue and mucosal structure, prokaryotic biota, and biochemical composition that would support microbial life. Neisseria meningitidis and the Bordetella species are discussed as examples of bacteria that have no known external reservoirs but have evolved to obligately colonize the mammalian upper respiratory tract.
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Arnal L, Grunert T, Cattelan N, de Gouw D, Villalba MI, Serra DO, Mooi FR, Ehling-Schulz M, Yantorno OM. Bordetella pertussis Isolates from Argentinean Whooping Cough Patients Display Enhanced Biofilm Formation Capacity Compared to Tohama I Reference Strain. Front Microbiol 2015; 6:1352. [PMID: 26696973 PMCID: PMC4672677 DOI: 10.3389/fmicb.2015.01352] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Accepted: 11/16/2015] [Indexed: 11/13/2022] Open
Abstract
Pertussis is a highly contagious disease mainly caused by Bordetella pertussis. Despite the massive use of vaccines, since the 1950s the disease has become re-emergent in 2000 with a shift in incidence from infants to adolescents and adults. Clearly, the efficacy of current cellular or acellular vaccines, formulated from bacteria grown in stirred bioreactors is limited, presenting a challenge for future vaccine development. For gaining insights into the role of B. pertussis biofilm development for host colonization and persistence within the host, we examined the biofilm forming capacity of eight argentinean clinical isolates recovered from 2001 to 2007. All clinical isolates showed an enhanced potential for biofilm formation compared to the reference strain Tohama I. We further selected the clinical isolate B. pertussis 2723, exhibiting the highest biofilm biomass production, for quantitative proteomic profiling by means of two-dimensional fluorescence difference gel electrophoresis (2D-DIGE) coupled with mass spectrometry, which was accompanied by targeted transcriptional analysis. Results revealed an elevated expression of several virulence factors, including adhesins involved in biofilm development. In addition, we observed a higher expression of energy metabolism enzymes in the clinical isolate compared to the Tohama I strain. Furthermore, all clinical isolates carried a polymorphism in the bvgS gene. This mutation was associated to an increased sensitivity to modulation and a faster rate of adhesion to abiotic surfaces. Thus, the phenotypic biofilm characteristics shown by the clinical isolates might represent an important, hitherto underestimated, adaptive strategy for host colonization and long time persistence within the host.
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Affiliation(s)
- Laura Arnal
- CINDEFI-Centro Científico Tecnológico CONICET La Plata, Facultad de Ciencias Exactas, Universidad Nacional de La Plata Buenos Aires, Argentina
| | - Tom Grunert
- Functional Microbiology, Institute of Microbiology, Department of Pathobiology, University of Veterinary Medicine Vienna Vienna, Austria
| | - Natalia Cattelan
- CINDEFI-Centro Científico Tecnológico CONICET La Plata, Facultad de Ciencias Exactas, Universidad Nacional de La Plata Buenos Aires, Argentina
| | - Daan de Gouw
- Laboratory of Pediatric Infectious Diseases, Department of Pediatrics, Radboud University Medical Centre Nijmegen, Netherlands ; Laboratory of Medical Immunology, Department of Laboratory Medicine, Radboud University Medical Centre Nijmegen, Netherlands
| | - María I Villalba
- CINDEFI-Centro Científico Tecnológico CONICET La Plata, Facultad de Ciencias Exactas, Universidad Nacional de La Plata Buenos Aires, Argentina
| | - Diego O Serra
- CINDEFI-Centro Científico Tecnológico CONICET La Plata, Facultad de Ciencias Exactas, Universidad Nacional de La Plata Buenos Aires, Argentina ; Mikrobiologie, Institut for Biologie, Humboldt-Universitat zu Berlin Berlin, Germany
| | - Frits R Mooi
- Netherlands Centre for Infectious Disease Control, National Institute for Public Health and the Environment Bilthoven, Netherlands
| | - Monika Ehling-Schulz
- Functional Microbiology, Institute of Microbiology, Department of Pathobiology, University of Veterinary Medicine Vienna Vienna, Austria
| | - Osvaldo M Yantorno
- CINDEFI-Centro Científico Tecnológico CONICET La Plata, Facultad de Ciencias Exactas, Universidad Nacional de La Plata Buenos Aires, Argentina
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de la Fuente-Núñez C, Reffuveille F, Mansour SC, Reckseidler-Zenteno SL, Hernández D, Brackman G, Coenye T, Hancock REW. D-enantiomeric peptides that eradicate wild-type and multidrug-resistant biofilms and protect against lethal Pseudomonas aeruginosa infections. ACTA ACUST UNITED AC 2015; 22:196-205. [PMID: 25699603 DOI: 10.1016/j.chembiol.2015.01.002] [Citation(s) in RCA: 221] [Impact Index Per Article: 24.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2014] [Revised: 12/11/2014] [Accepted: 01/06/2015] [Indexed: 12/26/2022]
Abstract
In many infections, bacteria form surface-associated communities known as biofilms that are substantially more resistant to antibiotics than their planktonic counterparts. Based on the design features of active antibiofilm peptides, we made a series of related 12-amino acid L-, D- and retro-inverso derivatives. Specific D-enantiomeric peptides were the most potent at inhibiting biofilm development and eradicating preformed biofilms of seven species of wild-type and multiply antibiotic-resistant Gram-negative pathogens. Moreover, these peptides showed strong synergy with conventional antibiotics, reducing the antibiotic concentrations required for complete biofilm inhibition by up to 64-fold. As shown previously for 1018, these D-amino acid peptides targeted the intracellular stringent response signal (p)ppGpp. The most potent peptides DJK-5 and DJK-6 protected invertebrates from lethal Pseudomonas aeruginosa infections and were considerably more active than a previously described L-amino acid peptide 1018. Thus, the protease-resistant peptides produced here were more effective both in vitro and in vivo.
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Affiliation(s)
- César de la Fuente-Núñez
- Department of Microbiology and Immunology, Centre for Microbial Diseases and Immunity Research, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - Fany Reffuveille
- Department of Microbiology and Immunology, Centre for Microbial Diseases and Immunity Research, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - Sarah C Mansour
- Department of Microbiology and Immunology, Centre for Microbial Diseases and Immunity Research, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | | | - Diego Hernández
- Faculty of Science and Technology, Athabasca University, Athabasca, AB T9S 3A3, Canada
| | - Gilles Brackman
- Laboratory of Pharmaceutical Microbiology, Ghent University, Harelbekestraat 72, 9000 Ghent, Belgium
| | - Tom Coenye
- Laboratory of Pharmaceutical Microbiology, Ghent University, Harelbekestraat 72, 9000 Ghent, Belgium
| | - Robert E W Hancock
- Department of Microbiology and Immunology, Centre for Microbial Diseases and Immunity Research, University of British Columbia, Vancouver, BC V6T 1Z4, Canada.
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Cattelan N, Dubey P, Arnal L, Yantorno OM, Deora R. Bordetella biofilms: a lifestyle leading to persistent infections. Pathog Dis 2015; 74:ftv108. [PMID: 26586694 DOI: 10.1093/femspd/ftv108] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/09/2015] [Indexed: 12/21/2022] Open
Abstract
Bordetella bronchiseptica and B. pertussis are Gram-negative bacteria that cause respiratory diseases in animals and humans. The current incidence of whooping cough or pertussis caused by B. pertussis has reached levels not observed since the 1950s. Although pertussis is traditionally known as an acute childhood disease, it has recently resurged in vaccinated adolescents and adults. These individuals often become silent carriers, facilitating bacterial circulation and transmission. Similarly, vaccinated and non-vaccinated animals continue to be carriers of B. bronchiseptica and shed bacteria resulting in disease outbreaks. The persistence mechanisms of these bacteria remain poorly characterized. It has been proposed that adoption of a biofilm lifestyle allows persistent colonization of the mammalian respiratory tract. The history of Bordetella biofilm research is only a decade long and there is no single review article that has exclusively focused on this area. We systematically discuss the role of Bordetella factors in biofilm development in vitro and in the mouse respiratory tract. We further outline the implications of biofilms to bacterial persistence and transmission in humans and for the design of new acellular pertussis vaccines.
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Affiliation(s)
- Natalia Cattelan
- Microbial Biofilm Laboratory, CINDEFI-CONICET-CCT La Plata, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, La Plata (1900), Argentina
| | - Purnima Dubey
- Department of Pathology, Wake Forest School of Medicine, Medical Center Blvd., Winston-Salem, NC 27157, USA
| | - Laura Arnal
- Microbial Biofilm Laboratory, CINDEFI-CONICET-CCT La Plata, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, La Plata (1900), Argentina
| | - Osvaldo M Yantorno
- Microbial Biofilm Laboratory, CINDEFI-CONICET-CCT La Plata, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, La Plata (1900), Argentina
| | - Rajendar Deora
- Department of Microbiology and Immunology, Wake Forest School of Medicine, Medical Center Blvd., Winston-Salem, NC 27157, USA
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Glutamate Limitation, BvgAS Activation, and (p)ppGpp Regulate the Expression of the Bordetella pertussis Type 3 Secretion System. J Bacteriol 2015; 198:343-51. [PMID: 26527639 DOI: 10.1128/jb.00596-15] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2015] [Accepted: 10/24/2015] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED Bordetella pertussis is a bacterium that is considered to be highly adapted to humans, and it has not been isolated from the environment. As this bacterium does not utilize sugars, the abundant supply of glutamate in Stainer Scholte (SS) medium enables B. pertussis to grow efficiently in liquid culture in vitro, and as such, SS medium is a popular choice for laboratory experiments. However, the concentration of glutamate in the in vivo niche of B. pertussis is quite low. We investigated the bacterial response to low concentrations of glutamate to elucidate bacterial physiology via the expression of the type 3 secretion system (T3SS), and we discuss its relationship to the Bvg mode in which the two-component regulator of pathogenesis (BvgAS) is activated. Glutamate limitation induced the expression of both the T3SS apparatus and effector genes at the transcriptional level. (p)ppGpp, a modulator of the stringent response, was necessary for maximum expression of the T3SS genes. These observations indicate that the expression of the T3SS is managed by nutrient starvation. In addition, the autoaggregation ability was high in the absence of glutamate and no autoaggregation was observed in glutamate-replete medium. Taken together, glutamate-limited conditions in Bvg(+) mode elicit the high expression of T3SS genes in B. pertussis and promotes its sessile form. IMPORTANCE Bordetella pertussis is a highly contagious pathogen that causes respiratory infectious disease. In spite of the increasing use of vaccination, the number of patients with pertussis is increasing. The proteins produced in vivo often are different from the protein profile under laboratory conditions; therefore, the development of conditions reflecting the host environment is important to understand native bacterial behavior. In the present study, we examined the effect of glutamate limitation, as its concentration in vivo is much lower than that in the culture medium currently used for B. pertussis experiments. As predicted, the T3SS was induced by glutamate limitation. These results are suggestive of the importance of regulation by nutrient conditions and in the pathogenicity of B. pertussis.
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Li G, Xie F, Zhang Y, Bossé JT, Langford PR, Wang C. Role of (p)ppGpp in Viability and Biofilm Formation of Actinobacillus pleuropneumoniae S8. PLoS One 2015; 10:e0141501. [PMID: 26509499 PMCID: PMC4624843 DOI: 10.1371/journal.pone.0141501] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2015] [Accepted: 10/08/2015] [Indexed: 12/04/2022] Open
Abstract
Actinobacillus pleuropneumoniae is a Gram-negative bacterium and the cause of porcine pleuropneumonia. When the bacterium encounters nutritional starvation, the relA-dependent (p)ppGpp-mediated stringent response is activated. The modified nucleotides guanosine 5’-diphosphate 3’-diphosphate (ppGpp) and guanosine 5’-triphosphate 3’-diphosphate (pppGpp) are known to be signaling molecules in other prokaryotes. Here, to investigate the role of (p)ppGpp in A. pleuropneumoniae, we created a mutant A. pleuropneumoniae strain, S8ΔrelA, which lacks the (p)ppGpp-synthesizing enzyme RelA, and investigated its phenotype in vitro. S8ΔrelA did not survive after stationary phase (starvation condition) and grew exclusively as non-extended cells. Compared to the wild-type (WT) strain, the S8ΔrelA mutant had an increased ability to form a biofilm. Transcriptional profiles of early stationary phase cultures revealed that a total of 405 bacterial genes were differentially expressed (including 380 up-regulated and 25 down-regulated genes) in S8ΔrelA as compared with the WT strain. Most of the up-regulated genes are involved in ribosomal structure and biogenesis, amino acid transport and metabolism, translation cell wall/membrane/envelope biogenesis. The data indicate that (p)ppGpp coordinates the growth, viability, morphology, biofilm formation and metabolic ability of A. pleuropneumoniae in starvation conditions. Furthermore, S8ΔrelA could not use certain sugars nor produce urease which has been associated with the virulence of A. pleuropneumoniae, suggesting that (p)ppGpp may directly or indirectly affect the pathogenesis of A. pleuropneumoniae during the infection process. In summary, (p)ppGpp signaling represents an essential component of the regulatory network governing stress adaptation and virulence in A. pleuropneumoniae.
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Affiliation(s)
- Gang Li
- Division of Bacterial Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China
| | - Fang Xie
- Division of Bacterial Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China
| | - Yanhe Zhang
- Division of Bacterial Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China
| | - Janine T. Bossé
- Section of Paediatrics, Department of Medicine, Imperial College London, St. Mary’s Campus, London, United Kingdom
| | - Paul R. Langford
- Section of Paediatrics, Department of Medicine, Imperial College London, St. Mary’s Campus, London, United Kingdom
| | - Chunlai Wang
- Division of Bacterial Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China
- * E-mail:
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28
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Little DJ, Milek S, Bamford NC, Ganguly T, DiFrancesco BR, Nitz M, Deora R, Howell PL. The protein BpsB is a poly-β-1,6-N-acetyl-D-glucosamine deacetylase required for biofilm formation in Bordetella bronchiseptica. J Biol Chem 2015. [PMID: 26203190 DOI: 10.1074/jbc.m115.672469] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Bordetella pertussis and Bordetella bronchiseptica are the causative agents of whooping cough in humans and a variety of respiratory diseases in animals, respectively. Bordetella species produce an exopolysaccharide, known as the Bordetella polysaccharide (Bps), which is encoded by the bpsABCD operon. Bps is required for Bordetella biofilm formation, colonization of the respiratory tract, and confers protection from complement-mediated killing. In this report, we have investigated the role of BpsB in the biosynthesis of Bps and biofilm formation by B. bronchiseptica. BpsB is a two-domain protein that localizes to the periplasm and outer membrane. BpsB displays metal- and length-dependent deacetylation on poly-β-1,6-N-acetyl-d-glucosamine (PNAG) oligomers, supporting previous immunogenic data that suggests Bps is a PNAG polymer. BpsB can use a variety of divalent metal cations for deacetylase activity and showed highest activity in the presence of Ni(2+) and Co(2+). The structure of the BpsB deacetylase domain is similar to the PNAG deacetylases PgaB and IcaB and contains the same circularly permuted family four carbohydrate esterase motifs. Unlike PgaB from Escherichia coli, BpsB is not required for polymer export and has unique structural differences that allow the N-terminal deacetylase domain to be active when purified in isolation from the C-terminal domain. Our enzymatic characterizations highlight the importance of conserved active site residues in PNAG deacetylation and demonstrate that the C-terminal domain is required for maximal deacetylation of longer PNAG oligomers. Furthermore, we show that BpsB is critical for the formation and complex architecture of B. bronchiseptica biofilms.
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Affiliation(s)
- Dustin J Little
- From the Program in Molecular Structure and Function, Research Institute, The Hospital for Sick Children, Toronto, Ontario M5G 1X8, the Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Sonja Milek
- the Department of Microbiology and Immunology, Wake Forest School of Medicine, Winston-Salem, North Carolina 27157, and
| | - Natalie C Bamford
- From the Program in Molecular Structure and Function, Research Institute, The Hospital for Sick Children, Toronto, Ontario M5G 1X8, the Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Tridib Ganguly
- the Department of Microbiology and Immunology, Wake Forest School of Medicine, Winston-Salem, North Carolina 27157, and
| | | | - Mark Nitz
- the Department of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada
| | - Rajendar Deora
- the Department of Microbiology and Immunology, Wake Forest School of Medicine, Winston-Salem, North Carolina 27157, and
| | - P Lynne Howell
- From the Program in Molecular Structure and Function, Research Institute, The Hospital for Sick Children, Toronto, Ontario M5G 1X8, the Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada,
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Lister JL, Horswill AR. Staphylococcus aureus biofilms: recent developments in biofilm dispersal. Front Cell Infect Microbiol 2015. [PMID: 25566513 DOI: 10.3389/fcimb201400178] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2023] Open
Abstract
Staphylococcus aureus is a major cause of nosocomial and community-acquired infections and represents a significant burden on the healthcare system. S. aureus attachment to medical implants and host tissue, and the establishment of a mature biofilm, play an important role in the persistence of chronic infections. The formation of a biofilm, and encasement of cells in a polymer-based matrix, decreases the susceptibility to antimicrobials and immune defenses, making these infections difficult to eradicate. During infection, dispersal of cells from the biofilm can result in spread to secondary sites and worsening of the infection. In this review, we discuss the current understanding of the pathways behind biofilm dispersal in S. aureus, with a focus on enzymatic and newly described broad-spectrum dispersal mechanisms. Additionally, we explore potential applications of dispersal in the treatment of biofilm-mediated infections.
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Affiliation(s)
- Jessica L Lister
- Department of Microbiology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa Iowa City, IA, USA
| | - Alexander R Horswill
- Department of Microbiology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa Iowa City, IA, USA
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30
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Abstract
UNLABELLED Volatiles are small air-transmittable chemicals with diverse biological activities. In this study, we showed that volatiles produced by the bacterium Bacillus subtilis had a profound effect on biofilm formation of neighboring B. subtilis cells that grew in proximity but were physically separated. We further demonstrated that one such volatile, acetic acid, is particularly potent in stimulating biofilm formation. Multiple lines of genetic evidence based on B. subtilis mutants that are defective in either acetic acid production or transportation suggest that B. subtilis uses acetic acid as a metabolic signal to coordinate the timing of biofilm formation. Lastly, we investigated how B. subtilis cells sense and respond to acetic acid in regulating biofilm formation. We showed the possible involvement of three sets of genes (ywbHG, ysbAB, and yxaKC), all encoding putative holin-antiholin-like proteins, in cells responding to acetic acid and stimulating biofilm formation. All three sets of genes were induced by acetate. A mutant with a triple mutation of those genes showed a severe delay in biofilm formation, whereas a strain overexpressing ywbHG showed early and robust biofilm formation. Results of our studies suggest that B. subtilis and possibly other bacteria use acetic acid as a metabolic signal to regulate biofilm formation as well as a quorum-sensing-like airborne signal to coordinate the timing of biofilm formation by physically separated cells in the community. IMPORTANCE Volatiles are small, air-transmittable molecules produced by all kingdoms of organisms including bacteria. Volatiles possess diverse biological activities and play important roles in bacteria-bacteria and bacteria-host interactions. Although volatiles can be used as a novel and important way of cell-cell communication due to their air-transmittable nature, little is known about how the volatile-mediated signaling mechanism works. In this study, we demonstrate that the bacterium Bacillus subtilis uses one such volatile, acetic acid, as a quorum-sensing-like signal to coordinate the timing of the formation of structurally complex cell communities, also known as biofilms. We further characterized the molecular mechanisms of how B. subtilis responds to acetic acid in stimulating biofilm formation. Our study also suggests that acetic acid may be used as a volatile signal for cross-species communication.
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Lister JL, Horswill AR. Staphylococcus aureus biofilms: recent developments in biofilm dispersal. Front Cell Infect Microbiol 2014; 4:178. [PMID: 25566513 PMCID: PMC4275032 DOI: 10.3389/fcimb.2014.00178] [Citation(s) in RCA: 376] [Impact Index Per Article: 37.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2014] [Accepted: 12/05/2014] [Indexed: 12/17/2022] Open
Abstract
Staphylococcus aureus is a major cause of nosocomial and community-acquired infections and represents a significant burden on the healthcare system. S. aureus attachment to medical implants and host tissue, and the establishment of a mature biofilm, play an important role in the persistence of chronic infections. The formation of a biofilm, and encasement of cells in a polymer-based matrix, decreases the susceptibility to antimicrobials and immune defenses, making these infections difficult to eradicate. During infection, dispersal of cells from the biofilm can result in spread to secondary sites and worsening of the infection. In this review, we discuss the current understanding of the pathways behind biofilm dispersal in S. aureus, with a focus on enzymatic and newly described broad-spectrum dispersal mechanisms. Additionally, we explore potential applications of dispersal in the treatment of biofilm-mediated infections.
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Affiliation(s)
- Jessica L Lister
- Department of Microbiology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa Iowa City, IA, USA
| | - Alexander R Horswill
- Department of Microbiology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa Iowa City, IA, USA
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32
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Broad-spectrum anti-biofilm peptide that targets a cellular stress response. PLoS Pathog 2014; 10:e1004152. [PMID: 24852171 PMCID: PMC4031209 DOI: 10.1371/journal.ppat.1004152] [Citation(s) in RCA: 368] [Impact Index Per Article: 36.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2014] [Accepted: 04/14/2014] [Indexed: 11/22/2022] Open
Abstract
Bacteria form multicellular communities known as biofilms that cause two thirds of all infections and demonstrate a 10 to 1000 fold increase in adaptive resistance to conventional antibiotics. Currently, there are no approved drugs that specifically target bacterial biofilms. Here we identified a potent anti-biofilm peptide 1018 that worked by blocking (p)ppGpp, an important signal in biofilm development. At concentrations that did not affect planktonic growth, peptide treatment completely prevented biofilm formation and led to the eradication of mature biofilms in representative strains of both Gram-negative and Gram-positive bacterial pathogens including Pseudomonas aeruginosa, Escherichia coli, Acinetobacter baumannii, Klebsiella pneumoniae, methicillin resistant Staphylococcus aureus, Salmonella Typhimurium and Burkholderia cenocepacia. Low levels of the peptide led to biofilm dispersal, while higher doses triggered biofilm cell death. We hypothesized that the peptide acted to inhibit a common stress response in target species, and that the stringent response, mediating (p)ppGpp synthesis through the enzymes RelA and SpoT, was targeted. Consistent with this, increasing (p)ppGpp synthesis by addition of serine hydroxamate or over-expression of relA led to reduced susceptibility to the peptide. Furthermore, relA and spoT mutations blocking production of (p)ppGpp replicated the effects of the peptide, leading to a reduction of biofilm formation in the four tested target species. Also, eliminating (p)ppGpp expression after two days of biofilm growth by removal of arabinose from a strain expressing relA behind an arabinose-inducible promoter, reciprocated the effect of peptide added at the same time, leading to loss of biofilm. NMR and chromatography studies showed that the peptide acted on cells to cause degradation of (p)ppGpp within 30 minutes, and in vitro directly interacted with ppGpp. We thus propose that 1018 targets (p)ppGpp and marks it for degradation in cells. Targeting (p)ppGpp represents a new approach against biofilm-related drug resistance. Bacteria colonize most environments, including the host by forming biofilms, which are extremely (adaptively) resistant to conventional antibiotics. Biofilms cause at least 65% of all human infections, being particularly prevalent in device-related infections, infections on body surfaces and in chronic infections. Currently there is a severe problem with antibiotic-resistant organisms, given the explosion of antibiotic resistance whereby our entire arsenal of antibiotics is gradually losing effectiveness, combined with the paucity of truly novel compounds under development or entering the clinic. Thus the even greater resistance of biofilms adds to the major concerns being expressed by physicians and medical authorities. Consequently, there is an urgent need for new strategies to treat biofilm infections and we demonstrate in the present study an approach, based on the inhibition of (p)ppGpp by a small peptide, that eradicates biofilms formed by four of the so-called ESKAPE pathogens, identified by the Infectious Diseases Society of America as the most recalcitrant and resistant organisms in our society. The strategy presented here represents a significant advance in the search for new agents that specifically target bacterial biofilms.
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relA enhances the adherence of enteropathogenic Escherichia coli. PLoS One 2014; 9:e91703. [PMID: 24643076 PMCID: PMC3958371 DOI: 10.1371/journal.pone.0091703] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2013] [Accepted: 02/14/2014] [Indexed: 11/19/2022] Open
Abstract
Enteropathogenic Escherichia coli (EPEC) is a known causative agent of diarrhea in children. In the process of colonization of the small intestine, EPEC synthesizes two types of adhesins, the bundle-forming pilus (BFP) and intimin. The BFP pilus is an adhesin associated with the initial stages of adherence of EPEC to epithelial cells, while the outer membrane protein intimin carries out the intimate adherence that takes place at the third stage of infection. BFP is encoded by the bfp operon located in plasmid EAF, present only in typical EPEC isolates, while eae, the gene that encodes intimin is situated in the LEE, a chromosomal pathogenicity island. Transcription of bfp and eae is regulated by the products of the perABC operon, also present in plasmid EAF. Here we show that deletion of relA, that encodes a guanosine penta and tetraphosphate synthetase impairs EPEC adherence to epithelial cells in vitro. In the absence of relA, the transcription of the regulatory operon perABC is reduced, resulting in lower levels of BFP and intimin. Bacterial adherence, BFP and intimin synthesis and perABC expression are restored upon complementation with the wild-type relA allele.
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Comparative analyses of a cystic fibrosis isolate of Bordetella bronchiseptica reveal differences in important pathogenic phenotypes. Infect Immun 2014; 82:1627-37. [PMID: 24470470 DOI: 10.1128/iai.01453-13] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Bordetella bronchiseptica is a Gram-negative bacterium that infects and causes disease in a wide variety of animals. B. bronchiseptica also infects humans, thereby demonstrating zoonotic transmission. An extensive characterization of human B. bronchiseptica isolates is needed to better understand the distinct genetic and phenotypic traits associated with these zoonotic transmission events. Using whole-genome transcriptome and CGH analysis, we report that a B. bronchiseptica cystic fibrosis isolate, T44625, contains a distinct genomic content of virulence-associated genes and differentially expresses these genes compared to the sequenced model laboratory strain RB50, a rabbit isolate. The differential gene expression pattern correlated with unique phenotypes exhibited by T44625, which included lower motility, increased aggregation, hyperbiofilm formation, and an increased in vitro capacity to adhere to respiratory epithelial cells. Using a mouse intranasal infection model, we found that although defective in establishing high bacterial burdens early during the infection process, T44625 persisted efficiently in the mouse nose. By documenting the unique genomic and phenotypic attributes of T44625, this report provides a blueprint for understanding the successful zoonotic potential of B. bronchiseptica and other zoonotic bacteria.
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