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Bacterial dormancy: A subpopulation of viable but non-culturable cells demonstrates better fitness for revival. PLoS Pathog 2021; 17:e1009194. [PMID: 33439894 PMCID: PMC7837498 DOI: 10.1371/journal.ppat.1009194] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Revised: 01/26/2021] [Accepted: 11/27/2020] [Indexed: 01/08/2023] Open
Abstract
The viable but non culturable (VBNC) state is a condition in which bacterial cells are viable and metabolically active, but resistant to cultivation using a routine growth medium. We investigated the ability of V. parahaemolyticus to form VBNC cells, and to subsequently become resuscitated. The ability to control VBNC cell formation in the laboratory allowed us to selectively isolate VBNC cells using fluorescence activated cell sorting, and to differentiate subpopulations based on their metabolic activity, cell shape and the ability to cause disease in Galleria mellonella. Our results showed that two subpopulations (P1 and P2) of V. parahaemolyticus VBNC cells exist and can remain dormant in the VBNC state for long periods. VBNC subpopulation P2, had a better fitness for survival under stressful conditions and showed 100% revival under favourable conditions. Proteomic analysis of these subpopulations (at two different time points: 12 days (T12) and 50 days (T50) post VBNC) revealed that the proteome of P2 was more similar to that of the starting microcosm culture (T0) than the proteome of P1. Proteins that were significantly up or down-regulated between the different VBNC populations were identified and differentially regulated proteins were assigned into 23 functional groups, the majority being assigned to metabolism functional categories. A lactate dehydrogenase (lldD) protein, responsible for converting lactate to pyruvate, was significantly upregulated in all subpopulations of VBNC cells. Deletion of the lactate dehydrogenase (RIMD2210633:ΔlldD) gene caused cells to enter the VBNC state significantly more quickly compared to the wild-type, and adding lactate to VBNC cells aided their resuscitation and extended the resuscitation window. Addition of pyruvate to the RIMD2210633:ΔlldD strain restored the wild-type VBNC formation profile. This study suggests that lactate dehydrogenase may play a role in regulating the VBNC state.
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Deng Y, Chen C, Zhao Z, Zhao J, Jacq A, Huang X, Yang Y. The RNA Chaperone Hfq Is Involved in Colony Morphology, Nutrient Utilization and Oxidative and Envelope Stress Response in Vibrio alginolyticus. PLoS One 2016; 11:e0163689. [PMID: 27685640 PMCID: PMC5042437 DOI: 10.1371/journal.pone.0163689] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2016] [Accepted: 09/13/2016] [Indexed: 12/26/2022] Open
Abstract
Hfq is a global regulator that is involved in environmental adaptation of bacteria and in pathogenicity. To gain insight into the role of Hfq in Vibrio alginolyticus, an hfq deletion mutant was constructed in V. alginolyticus ZJ-T strain and phenotypically characterized. Deletion of hfq led to an alteration of colony morphology and reduced extracellular polysaccharide production, a general impairment of growth in both rich medium and minimal media with different carbon sources or amino acids, enhanced sensitivity to oxidative stress and to several antibiotics. Furthermore, a differential transcriptomic analysis showed significant changes of transcript abundance for 306 protein coding genes, with 179 genes being up regulated and 127 down-regulated. Several of these changes could be related to the observed phenotypes of the mutant. Transcriptomic data also provided evidence for the induction of the extracytoplasmic stress response in absence of Hfq. Altogether, these findings point to broad regulatory functions for Hfq in V. alginolyticus cells, likely to underlie an important role in pathogenicity.
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Affiliation(s)
- Yiqin Deng
- Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China
- Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Chang Chen
- Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China
- Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China
- Xisha/Nansha Ocean observation and research station, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China
- * E-mail:
| | - Zhe Zhao
- Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China
- Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China
| | - Jingjing Zhao
- Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China
- Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China
| | - Annick Jacq
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Xiaochun Huang
- Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China
- Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Yiying Yang
- Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China
- Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China
- University of Chinese Academy of Sciences, Beijing, China
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Feliciano JR, Grilo AM, Guerreiro SI, Sousa SA, Leitão JH. Hfq: a multifaceted RNA chaperone involved in virulence. Future Microbiol 2015; 11:137-51. [PMID: 26685037 DOI: 10.2217/fmb.15.128] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Hfq has emerged in recent years as a master regulator of gene expression in bacteria, mainly due to its ability to mediate the interaction of small noncoding RNAs with their mRNA targets, including those related to virulence in Gram-negative bacteria. In this work, we review current knowledge on the involvement of Hfq in the regulation of virulence traits related to secretion systems, alternative sigma factors, outer membrane proteins, polysaccharides and iron metabolism. Recent data from transcriptomics and proteomics studies performed for major pathogens are included. We also summarize and correlate current knowledge on how Hfq protein impacts pathogenicity of bacterial pathogens.
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Affiliation(s)
- Joana R Feliciano
- iBB - Instituto de Bioengenharia e Biociências, Instituto Superior Técnico, Universidade de Lisboa. Av. Rovisco Pais, 1049-001 Lisboa, Portugal
| | | | - Soraia I Guerreiro
- iBB - Instituto de Bioengenharia e Biociências, Instituto Superior Técnico, Universidade de Lisboa. Av. Rovisco Pais, 1049-001 Lisboa, Portugal
| | - Sílvia A Sousa
- iBB - Instituto de Bioengenharia e Biociências, Instituto Superior Técnico, Universidade de Lisboa. Av. Rovisco Pais, 1049-001 Lisboa, Portugal
| | - Jorge H Leitão
- iBB - Instituto de Bioengenharia e Biociências, Instituto Superior Técnico, Universidade de Lisboa. Av. Rovisco Pais, 1049-001 Lisboa, Portugal.,Departamento de Bioengenharia, Instituto Superior Técnico, Universidade de Lisboa. Av. Rovisco Pais, 1049-001 Lisboa, Portugal
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Nguyen AN, Jacq A. Small RNAs in the Vibrionaceae: an ocean still to be explored. WILEY INTERDISCIPLINARY REVIEWS-RNA 2014; 5:381-92. [PMID: 24458378 DOI: 10.1002/wrna.1218] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2013] [Revised: 12/13/2013] [Accepted: 12/16/2013] [Indexed: 11/09/2022]
Abstract
In bacteria, the discovery of noncoding small RNAs (sRNAs) as modulators of gene expression in response to environmental signals has brought new insights into bacterial gene regulation, including control of pathogenicity. The Vibrionaceae constitute a family of marine bacteria of which many are responsible for infections affecting not only humans, such as Vibrio cholerae but also fish and marine invertebrates, representing the major cause of mortality in farmed marine species. They are able to colonize many habitats, existing as planktonic forms, in biofilms or associated with various hosts. This high adaptability is linked to their capacity to generate genetic diversity, in part through lateral gene transfer, but also by varying gene expression control. In the recent years, several major studies have illustrated the importance of small regulatory sRNAs in the Vibrionaceae for the control of pathogenicity and adaptation to environment and nutrient sources such as chitin, especially in V. cholerae and Vibrio harveyi. The existence of a complex regulatory network controlled by quorum sensing has been demonstrated in which sRNAs play central roles. This review covers major advances made in the discovery and elucidation of functions of Vibrionaceae sRNAs within the last 10 years.
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Affiliation(s)
- An Ngoc Nguyen
- Institut de Génétique et Microbiologie, UMR 8621 CNRS-Université Paris-Sud, 91405 Orsay Cedex, France
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Vatansever F, de Melo WCMA, Avci P, Vecchio D, Sadasivam M, Gupta A, Chandran R, Karimi M, Parizotto NA, Yin R, Tegos GP, Hamblin MR. Antimicrobial strategies centered around reactive oxygen species--bactericidal antibiotics, photodynamic therapy, and beyond. FEMS Microbiol Rev 2013; 37:955-89. [PMID: 23802986 DOI: 10.1111/1574-6976.12026] [Citation(s) in RCA: 578] [Impact Index Per Article: 52.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2012] [Revised: 05/15/2013] [Accepted: 05/16/2013] [Indexed: 12/13/2022] Open
Abstract
Reactive oxygen species (ROS) can attack a diverse range of targets to exert antimicrobial activity, which accounts for their versatility in mediating host defense against a broad range of pathogens. Most ROS are formed by the partial reduction in molecular oxygen. Four major ROS are recognized comprising superoxide (O2•-), hydrogen peroxide (H2O2), hydroxyl radical (•OH), and singlet oxygen ((1)O2), but they display very different kinetics and levels of activity. The effects of O2•- and H2O2 are less acute than those of •OH and (1)O2, because the former are much less reactive and can be detoxified by endogenous antioxidants (both enzymatic and nonenzymatic) that are induced by oxidative stress. In contrast, no enzyme can detoxify •OH or (1)O2, making them extremely toxic and acutely lethal. The present review will highlight the various methods of ROS formation and their mechanism of action. Antioxidant defenses against ROS in microbial cells and the use of ROS by antimicrobial host defense systems are covered. Antimicrobial approaches primarily utilizing ROS comprise both bactericidal antibiotics and nonpharmacological methods such as photodynamic therapy, titanium dioxide photocatalysis, cold plasma, and medicinal honey. A brief final section covers reactive nitrogen species and related therapeutics, such as acidified nitrite and nitric oxide-releasing nanoparticles.
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Affiliation(s)
- Fatma Vatansever
- The Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, MA, USA; Department of Dermatology, Harvard Medical School, Boston, MA, USA
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The Vibrio parahaemolyticus small RNA RyhB promotes production of the siderophore vibrioferrin by stabilizing the polycistronic mRNA. J Bacteriol 2013; 195:3692-703. [PMID: 23772063 DOI: 10.1128/jb.00162-13] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
High-affinity iron acquisition in Vibrio parahaemolyticus is mediated by the cognate siderophore vibrioferrin. We have previously reported that the vibrioferrin biosynthesis operon (pvsOp) is regulated at the transcriptional level by the iron-responsive repressor Fur (T. Tanabe, T. Funahashi, H. Nakao, S. Miyoshi, S. Shinoda, and S. Yamamoto, J. Bacteriol. 185:6938-6949, 2003). In this study, we identified the Fur-regulated small RNA RyhB and the RNA chaperone Hfq protein as additional regulatory proteins of vibrioferrin biosynthesis. We found that vibrioferrin production was greatly impaired in both the ryhB and hfq deletion mutants, and a TargetRNA search (http://snowwhite.wellesley.edu/targetRNA/index2.html) revealed that the 5'-untranslated region of pvsOp mRNA (pvsOp 5'-UTR) contains a potential base-pairing region required for the formation of the RyhB-pvsOp 5'-UTR duplex. An electrophoresis mobility shift assay indicated that RyhB can directly bind to the pvsOp 5'-UTR with the aid of Hfq. Rifampin chase experiments indicated that the half-life of pvsOp mRNA in the ryhB and hfq mutants was approximately 3-fold shorter than that in the parental strain, suggesting that both RyhB and Hfq are engaged in the stabilization of pvsOp mRNA. Chrome azurol S assays followed by electrophoresis mobility shift assays and rifampin chase experiments carried out for mutant strains indicated that base pairing between RyhB and the pvsOp 5'-UTR results in an increase in the stability of pvsOp mRNA, thereby leading to the promotion of vibrioferrin production. It is unprecedented that RyhB confers increased stability on a polycistronic mRNA involved in siderophore biosynthesis as a direct target.
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The RNA chaperone Hfq promotes fitness of Actinobacillus pleuropneumoniae during porcine pleuropneumonia. Infect Immun 2013; 81:2952-61. [PMID: 23732171 DOI: 10.1128/iai.00392-13] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Actinobacillus pleuropneumoniae is the etiological agent of porcine pleuropneumonia, an economically important disease of pigs. The hfq gene in A. pleuropneumoniae, encoding the RNA chaperone and posttranscriptional regulator Hfq, is upregulated during infection of porcine lungs. To investigate the role of this in vivo-induced gene in A. pleuropneumoniae, an hfq mutant strain was constructed. The hfq mutant was defective in biofilm formation on abiotic surfaces. The level of pgaC transcript, encoding the biosynthesis of poly-β-1,6-N-acetylglucosamine (PNAG), a major biofilm matrix component, was lower and PNAG content was 10-fold lower in the hfq mutant than in the wild-type strain. When outer membrane proteins were examined, cysteine synthase, implicated in resistance to oxidative stress and tellurite, was not found at detectable levels in the absence of Hfq. The hfq mutant displayed enhanced sensitivity to superoxide generated by methyl viologen and tellurite. These phenotypes were readily reversed by complementation with the hfq gene expressed from its native promoter. The role of Hfq in the fitness of A. pleuropneumoniae was assessed in a natural host infection model. The hfq mutant failed to colonize porcine lungs and was outcompeted by the wild-type strain (median competitive index of 2 × 10(-5)). Our data demonstrate that the in vivo-induced gene hfq is involved in the regulation of PNAG-dependent biofilm formation, resistance to superoxide stress, and the fitness and virulence of A. pleuropneumoniae in pigs and begin to elucidate the role of an in vivo-induced gene in the pathogenesis of pleuropneumonia.
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