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Liu P, Yue C, Liu L, Gao C, Lyu Y, Deng S, Tian H, Jia X. The function of small RNA in Pseudomonas aeruginosa. PeerJ 2022; 10:e13738. [PMID: 35891650 PMCID: PMC9308961 DOI: 10.7717/peerj.13738] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Accepted: 06/25/2022] [Indexed: 01/17/2023] Open
Abstract
Pseudomonas aeruginosa, the main conditional pathogen causing nosocomial infection, is a gram-negative bacterium with the largest genome among the known bacteria. The main reasons why Pseudomonas aeruginosa is prone to drug-resistant strains in clinic are: the drug-resistant genes in its genome and the drug resistance easily induced by single antibiotic treatment. With the development of high-throughput sequencing technology and bioinformatics, the functions of various small RNAs (sRNA) in Pseudomonas aeruginosa are being revealed. Different sRNAs regulate gene expression by binding to protein or mRNA to play an important role in the complex regulatory network. In this article, first, the importance and biological functions of different sRNAs in Pseudomonas aeruginosa are explored, and then the evidence and possibilities that sRNAs served as drug therapeutic targets are discussed, which may introduce new directions to develop novel disease treatment strategies.
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Affiliation(s)
- Pei Liu
- Yan’an University, Key Laboratory of Microbial Drugs Innovation and Transformation, Yan’an, Shaanxi, China
| | - Changwu Yue
- Yan’an University, Key Laboratory of Microbial Drugs Innovation and Transformation, Yan’an, Shaanxi, China
| | - Lihua Liu
- Chengdu Medical College, Non-coding RNA and Drug Discovery Key Laboratory of Sichuan Province, Chengdu, Sichuan, China
| | - Can Gao
- Yan’an University, Key Laboratory of Microbial Drugs Innovation and Transformation, Yan’an, Shaanxi, China
| | - Yuhong Lyu
- Yan’an University, Key Laboratory of Microbial Drugs Innovation and Transformation, Yan’an, Shaanxi, China
| | - Shanshan Deng
- Chengdu Medical College, Non-coding RNA and Drug Discovery Key Laboratory of Sichuan Province, Chengdu, Sichuan, China
| | - Hongying Tian
- Yan’an University, Key Laboratory of Microbial Drugs Innovation and Transformation, Yan’an, Shaanxi, China
| | - Xu Jia
- Chengdu Medical College, Non-coding RNA and Drug Discovery Key Laboratory of Sichuan Province, Chengdu, Sichuan, China,School of Basic Medical Science, Chengdu Medical College, Chengdu, Sichuan, China
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2
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Specific and Global RNA Regulators in Pseudomonas aeruginosa. Int J Mol Sci 2021; 22:ijms22168632. [PMID: 34445336 PMCID: PMC8395346 DOI: 10.3390/ijms22168632] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Revised: 08/05/2021] [Accepted: 08/08/2021] [Indexed: 01/20/2023] Open
Abstract
Pseudomonas aeruginosa (Pae) is an opportunistic pathogen showing a high intrinsic resistance to a wide variety of antibiotics. It causes nosocomial infections that are particularly detrimental to immunocompromised individuals and to patients suffering from cystic fibrosis. We provide a snapshot on regulatory RNAs of Pae that impact on metabolism, pathogenicity and antibiotic susceptibility. Different experimental approaches such as in silico predictions, co-purification with the RNA chaperone Hfq as well as high-throughput RNA sequencing identified several hundreds of regulatory RNA candidates in Pae. Notwithstanding, using in vitro and in vivo assays, the function of only a few has been revealed. Here, we focus on well-characterized small base-pairing RNAs, regulating specific target genes as well as on larger protein-binding RNAs that sequester and thereby modulate the activity of translational repressors. As the latter impact large gene networks governing metabolism, acute or chronic infections, these protein-binding RNAs in conjunction with their cognate proteins are regarded as global post-transcriptional regulators.
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3
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The LysR-Type Transcriptional Regulator BsrA (PA2121) Controls Vital Metabolic Pathways in Pseudomonas aeruginosa. mSystems 2021; 6:e0001521. [PMID: 34254827 PMCID: PMC8407307 DOI: 10.1128/msystems.00015-21] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Pseudomonas aeruginosa, a facultative human pathogen causing nosocomial infections, has complex regulatory systems involving many transcriptional regulators. LTTR (LysR-Type Transcriptional Regulator) family proteins are involved in the regulation of various processes, including stress responses, motility, virulence, and amino acid metabolism. The aim of this study was to characterize the LysR-type protein BsrA (PA2121), previously described as a negative regulator of biofilm formation in P. aeruginosa. Genome wide identification of BsrA binding sites using chromatin immunoprecipitation and sequencing analysis revealed 765 BsrA-bound regions in the P. aeruginosa PAO1161 genome, including 367 sites in intergenic regions. The motif T-N11-A was identified within sequences bound by BsrA. Transcriptomic analysis showed altered expression of 157 genes in response to BsrA excess; of these, 35 had a BsrA binding site within their promoter regions, suggesting a direct influence of BsrA on the transcription of these genes. BsrA-repressed loci included genes encoding proteins engaged in key metabolic pathways such as the tricarboxylic acid cycle. The panel of loci possibly directly activated by BsrA included genes involved in pilus/fimbria assembly, as well as secretion and transport systems. In addition, DNA pull-down and regulatory analyses showed the involvement of PA2551, PA3398, and PA5189 in regulation of bsrA expression, indicating that this gene is part of an intricate regulatory network. Taken together, these findings reveal the existence of a BsrA regulon, which performs important functions in P. aeruginosa. IMPORTANCE This study shows that BsrA, a LysR-type transcriptional regulator from Pseudomonas aeruginosa, previously identified as a repressor of biofilm synthesis, is part of an intricate global regulatory network. BsrA acts directly and/or indirectly as the repressor and/or activator of genes from vital metabolic pathways (e.g., pyruvate, acetate, and tricarboxylic acid cycle) and is involved in control of transport functions and the formation of surface appendages. Expression of the bsrA gene is increased in the presence of antibiotics, which suggests its induction in response to stress, possibly reflecting the need to redirect metabolism under stressful conditions. This is particularly relevant for the treatment of infections caused by P. aeruginosa. In summary, the findings of this study demonstrate that the BsrA regulator performs important roles in carbon metabolism, biofilm formation, and antibiotic resistance in P. aeruginosa.
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Hou S, Zhang J, Ma X, Hong Q, Fang L, Zheng G, Huang J, Gao Y, Xu Q, Zhuang X, Song X. Role of rgsA in Oxidative Stress Resistance in Pseudomonas aeruginosa. Curr Microbiol 2021; 78:3133-3141. [PMID: 34185129 DOI: 10.1007/s00284-021-02580-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Accepted: 06/13/2021] [Indexed: 10/21/2022]
Abstract
Pseudomonas aeruginosa is a common opportunistic pathogen that causes infections in vulnerable patients including those with metabolic disorders, hematologic diseases, and malignancies, and in those who have undergone surgery. In addition, P. aeruginosa exhibits high intrinsic resistance to numerous antibiotics and tends to form biofilms rendering it even more refractory to treatment. Among the mechanisms used by P. aeruginosa to adapt to environmental stresses are those involving small regulatory RNAs (sRNAs), which are 40-500 nucleotides long and are ubiquitous in bacteria. sRNAs play important regulatory roles in various vital processes in diverse bacteria, with their quantity and diversity of regulatory functions exceeding those of proteins. In this study, we show that deletion of the sRNA, rgsA, decreased the growth rate of P. aeruginosa. Furthermore, ΔrgsA P. aeruginosa exhibited decreased ability to resist the stress induced by exposure to different concentrations and durations of peroxides in both planktonic and biofilm growth modes compared with the wild-type strain. These results highlight the role of rgsA in the defense of P. aeruginosa against oxidative stress.
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Affiliation(s)
- Shuyi Hou
- Department of Clinical Laboratory, Xiang'an Hospital of Xiamen University, 2000 Xiangan Dong Road, Xiamen, 361000, Fujian, China
| | - Jiaqin Zhang
- Department of Clinical Laboratory, The First Affiliated Hospital of Xiamen University, 55 Zhenhai Road, Xiamen, 361000, Fujian, China. .,Xiamen Key Laboratory of Genetic Testing, 55 Zhenhai Road, Xiamen, 361000, Fujian, China.
| | - Xiaobo Ma
- Department of Clinical Laboratory, The First Affiliated Hospital of Xiamen University, 55 Zhenhai Road, Xiamen, 361000, Fujian, China
| | - Qiang Hong
- Department of Clinical Laboratory, The First Affiliated Hospital of Xiamen University, 55 Zhenhai Road, Xiamen, 361000, Fujian, China
| | - Lili Fang
- Department of Clinical Laboratory, The First Affiliated Hospital of Xiamen University, 55 Zhenhai Road, Xiamen, 361000, Fujian, China
| | - Gangsen Zheng
- Department of Clinical Laboratory, The First Affiliated Hospital of Xiamen University, 55 Zhenhai Road, Xiamen, 361000, Fujian, China
| | - Jiaming Huang
- Department of Clinical Laboratory, The Second Affiliated Hospital of Fujian Medical University, 34 Zhongshan North Road, Quanzhou, 362000, Fujian, China
| | - Yingchun Gao
- Department of Clinical Laboratory, The First People's Hospital of Xiaoshan District, 199 Shixin Nan Road, Hangzhou, 311200, Zhejiang, China
| | - Qiaoli Xu
- Department of Clinical Laboratory, Zhangzhou Affiliated Hospital of Fujian Medical University, 59 Shengli Road, Zhangzhou, 363000, Fujian, China
| | - Xinguo Zhuang
- Department of Clinical Laboratory, The First Affiliated Hospital of Xiamen University, 55 Zhenhai Road, Xiamen, 361000, Fujian, China
| | - Xiuyu Song
- Xiamen Blood Centre, 121 Hubin Nan Road, Xiamen, 361000, Fujian, China.
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5
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Ortet P, Fochesato S, Bitbol AF, Whitworth DE, Lalaouna D, Santaella C, Heulin T, Achouak W, Barakat M. Evolutionary history expands the range of signaling interactions in hybrid multikinase networks. Sci Rep 2021; 11:11763. [PMID: 34083699 PMCID: PMC8175716 DOI: 10.1038/s41598-021-91260-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Accepted: 05/19/2021] [Indexed: 12/02/2022] Open
Abstract
Two-component systems (TCSs) are ubiquitous signaling pathways, typically comprising a sensory histidine kinase (HK) and a response regulator, which communicate via intermolecular kinase-to-receiver domain phosphotransfer. Hybrid HKs constitute non-canonical TCS signaling pathways, with transmitter and receiver domains within a single protein communicating via intramolecular phosphotransfer. Here, we report how evolutionary relationships between hybrid HKs can be used as predictors of potential intermolecular and intramolecular interactions (‘phylogenetic promiscuity’). We used domain-swap genes chimeras to investigate the specificity of phosphotransfer within hybrid HKs of the GacS–GacA multikinase network of Pseudomonas brassicacearum. The receiver domain of GacS was replaced with those from nine donor hybrid HKs. Three chimeras with receivers from other hybrid HKs demonstrated correct functioning through complementation of a gacS mutant, which was dependent on strains having a functional gacA. Formation of functional chimeras was predictable on the basis of evolutionary heritage, and raises the possibility that HKs sharing a common ancestor with GacS might remain components of the contemporary GacS network. The results also demonstrate that understanding the evolutionary heritage of signaling domains in sophisticated networks allows their rational rewiring by simple domain transplantation, with implications for the creation of designer networks and inference of functional interactions.
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Affiliation(s)
- Philippe Ortet
- Aix Marseille Univ, CEA, CNRS, BIAM, LEMIRE, 13108, Saint Paul-Lez-Durance, France
| | - Sylvain Fochesato
- Aix Marseille Univ, CEA, CNRS, BIAM, LEMIRE, 13108, Saint Paul-Lez-Durance, France
| | - Anne-Florence Bitbol
- CNRS, Institut de Biologie Paris-Seine, Laboratoire Jean Perrin (UMR8237), Sorbonne Université, 75005, Paris, France.,Institute of Bioengineering, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015, Lausanne, Switzerland
| | - David E Whitworth
- Institute of Biological, Environmental and Rural Sciences, Aberystwyth University, Ceredigion, SY23 3DD, UK
| | - David Lalaouna
- Aix Marseille Univ, CEA, CNRS, BIAM, LEMIRE, 13108, Saint Paul-Lez-Durance, France.,CNRS, ARN UPR 9002, Université de Strasbourg, 67000, Strasbourg, France
| | - Catherine Santaella
- Aix Marseille Univ, CEA, CNRS, BIAM, LEMIRE, 13108, Saint Paul-Lez-Durance, France
| | - Thierry Heulin
- Aix Marseille Univ, CEA, CNRS, BIAM, LEMIRE, 13108, Saint Paul-Lez-Durance, France
| | - Wafa Achouak
- Aix Marseille Univ, CEA, CNRS, BIAM, LEMIRE, 13108, Saint Paul-Lez-Durance, France
| | - Mohamed Barakat
- Aix Marseille Univ, CEA, CNRS, BIAM, LEMIRE, 13108, Saint Paul-Lez-Durance, France.
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6
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Piattelli E, Peltier J, Soutourina O. Interplay between Regulatory RNAs and Signal Transduction Systems during Bacterial Infection. Genes (Basel) 2020; 11:E1209. [PMID: 33081172 PMCID: PMC7602753 DOI: 10.3390/genes11101209] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Revised: 10/08/2020] [Accepted: 10/13/2020] [Indexed: 12/13/2022] Open
Abstract
The ability of pathogenic bacteria to stably infect the host depends on their capacity to respond and adapt to the host environment and on the efficiency of their defensive mechanisms. Bacterial envelope provides a physical barrier protecting against environmental threats. It also constitutes an important sensory interface where numerous sensing systems are located. Signal transduction systems include Two-Component Systems (TCSs) and alternative sigma factors. These systems are able to sense and respond to the ever-changing environment inside the host, altering the bacterial transcriptome to mitigate the impact of the stress. The regulatory networks associated with signal transduction systems comprise small regulatory RNAs (sRNAs) that can be directly involved in the expression of virulence factors. The aim of this review is to describe the importance of TCS- and alternative sigma factor-associated sRNAs in human pathogens during infection. The currently available genome-wide approaches for studies of TCS-regulated sRNAs will be discussed. The differences in the signal transduction mediated by TCSs between bacteria and higher eukaryotes and the specificity of regulatory RNAs for their targets make them appealing targets for discovery of new strategies to fight against multi-resistant bacteria.
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Affiliation(s)
- Emma Piattelli
- Institute for Integrative Biology of the Cell (I2BC), CNRS, CEA, Université Paris-Saclay, 91198 Gif-sur-Yvette, France; (E.P.); (J.P.)
| | - Johann Peltier
- Institute for Integrative Biology of the Cell (I2BC), CNRS, CEA, Université Paris-Saclay, 91198 Gif-sur-Yvette, France; (E.P.); (J.P.)
- Laboratoire Pathogenèses des Bactéries Anaérobies, Institut Pasteur, UMR CNRS 2001, Université de Paris, 75015 Paris, France
| | - Olga Soutourina
- Institute for Integrative Biology of the Cell (I2BC), CNRS, CEA, Université Paris-Saclay, 91198 Gif-sur-Yvette, France; (E.P.); (J.P.)
- Institut Universitaire de France, CEDEX 05, 75231 Paris, France
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7
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Zhang Y, Zhang B, Wu X, Zhang LQ. Characterization the role of GacA-dependent small RNAs and RsmA family proteins on 2,4-diacetylphloroglucinol production in Pseudomonas fluorescens 2P24. Microbiol Res 2019; 233:126391. [PMID: 31865097 DOI: 10.1016/j.micres.2019.126391] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2019] [Revised: 11/26/2019] [Accepted: 12/07/2019] [Indexed: 10/25/2022]
Abstract
Pseudomonas fluorescens 2P24 is a plant-beneficial rhizobacteria that controls many root diseases caused by soil-borne pathogens, and the production of the antibiotic compound 2,4-diacetylphloroglucinol (2,4-DAPG) is essential for its biocontrol ability. In the present study, we investigated the regulatory mechanism acting on the production of 2,4-DAPG by the GacA-dependent small non-coding RNAs (sRNAs) and RsmA/E proteins in strain 2P24. Our results showed that the GacS-GacA system regulates the expression of the phlACBD locus, which is responsible for 2,4-DAPG production, by inducing the expression of rsmX, rsmX1, rsmY, and rsmZ. A novel GacA-regulated sRNA, RgsA, was found to negatively regulate 2,4-DAPG production. Activation of the phlACBD locus by the GacS-GacA system is mediated through RsmA and RsmE proteins (but not RsmI), which inhibit phlACBD translation by binding to the putative RsmA/E recognition element in the phlACBD leader. Taken together, our results suggested that in P. fluorescens 2P24, the GacS-GacA system controls the cellular 2,4-DAPG levels in the cell by fine-tuning the function of sRNAs in P. fluorescens.
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Affiliation(s)
- Yang Zhang
- College of Agriculture, Guangxi University, Nanning 530004, China
| | - Bo Zhang
- College of Agriculture, Guangxi University, Nanning 530004, China
| | - Xiaogang Wu
- College of Agriculture, Guangxi University, Nanning 530004, China.
| | - Li-Qun Zhang
- Department of Plant Pathology, China Agricultural University, Beijing 100193, China.
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8
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Hu G, Hu T, Zhan Y, Lu W, Lin M, Huang Y, Yan Y. NfiS, a species-specific regulatory noncoding RNA of Pseudomonas stutzeri, enhances oxidative stress tolerance in Escherichia coli. AMB Express 2019; 9:156. [PMID: 31555995 PMCID: PMC6761216 DOI: 10.1186/s13568-019-0881-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2019] [Accepted: 09/17/2019] [Indexed: 12/20/2022] Open
Abstract
Noncoding RNAs (ncRNAs) can finely control the expression of target genes at the posttranscriptional level in prokaryotes. Regulatory small RNAs (sRNAs) designed to control target gene expression for applications in metabolic engineering and synthetic biology have been successfully developed and used. However, the effect on the heterologous expression of species- or strain-specific ncRNAs in other bacterial strains remains poorly understood. In this work, a Pseudomonas stutzeri species-specific regulatory ncRNA, NfiS, which has been shown to play an important role in the response to oxidative stress as well as osmotic stress in P. stutzeri A1501, was cloned and transferred to the Escherichia coli strain Trans10. Recombinant NfiS-expressing E. coli, namely, Trans10-nfiS, exhibited significant enhancement of tolerance to oxidative stress. To map the possible gene regulatory networks mediated by NfiS in E. coli under oxidative stress, a microarray assay was performed to delineate the transcriptomic differences between Trans10-nfiS and wild-type E. coli under H2O2 shock treatment conditions. In all, 1184 genes were found to be significantly altered, and these genes were divided into mainly five functional categories: stress response, regulation, metabolism related, transport or membrane protein and unknown function. Our results suggest that the P. stutzeri species-specific ncRNA NfiS acts as a regulator that integrates adaptation to H2O2 with other cellular stress responses and helps protect E. coli cells against oxidative damage.
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9
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The Pseudomonas stutzeri-Specific Regulatory Noncoding RNA NfiS Targets katB mRNA Encoding a Catalase Essential for Optimal Oxidative Resistance and Nitrogenase Activity. J Bacteriol 2019; 201:JB.00334-19. [PMID: 31262840 PMCID: PMC6755748 DOI: 10.1128/jb.00334-19] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Accepted: 06/25/2019] [Indexed: 12/18/2022] Open
Abstract
Pseudomonas stutzeri A1501 is a versatile nitrogen-fixing bacterium capable of living in diverse environments and coping with various oxidative stresses. NfiS, a regulatory noncoding RNA (ncRNA) involved in the control of nitrogen fixation in A1501, was previously shown to be required for optimal resistance to H2O2; however, the precise role of NfiS and the target genes involved in the oxidative stress response is entirely unknown. In this work, we systematically investigated the NfiS-based mechanisms underlying the response of this bacterium to H2O2 at the cellular and molecular levels. A mutant strain carrying a deletion of nfiS showed significant downregulation of oxidative stress response genes, especially katB, a catalase gene, and oxyR, an essential regulator for transcription of catalase genes. Secondary structure prediction revealed two binding sites in NfiS for katB mRNA. Complementation experiments using truncated nfiS genes showed that each of two sites is functional, but not sufficient, for NfiS-mediated regulation of oxidative stress resistance and nitrogenase activities. Microscale thermophoresis assays further indicated direct base pairing between katB mRNA and NfiS at both sites 1 and 2, thus enhancing the half-life of the transcript. We also demonstrated that katB expression is dependent on OxyR and that both OxyR and KatB are essential for optimal oxidative stress resistance and nitrogenase activities. H2O2 at low concentrations was detoxified by KatB, leaving O2 as a by-product to support nitrogen fixation under O2-insufficient conditions. Moreover, our data suggest that the direct interaction between NfiS and katB mRNA is a conserved and widespread mechanism among P. stutzeri strains.IMPORTANCE Protection against oxygen damage is crucial for survival of nitrogen-fixing bacteria due to the extreme oxygen sensitivity of nitrogenase. This work exemplifies how the small ncRNA NfiS coordinates oxidative stress response and nitrogen fixation via base pairing with katB mRNA and nifK mRNA. Hence, NfiS acts as a molecular link to coordinate the expression of genes involved in oxidative stress response and nitrogen fixation. Our study provides the first insight into the biological functions of NfiS in oxidative stress regulation and adds a new regulation level to the mechanisms that contribute to the oxygen protection of the MoFe nitrogenase.
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10
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Fitting Pieces into the Puzzle of Pseudomonas aeruginosa Type III Secretion System Gene Expression. J Bacteriol 2019; 201:JB.00209-19. [PMID: 31010903 DOI: 10.1128/jb.00209-19] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Type III secretion systems (T3SS) are widely distributed in Gram-negative microorganisms and critical for host-pathogen and host-symbiont interactions with plants and animals. Central features of the T3SS are a highly conserved set of secretion and translocation genes and contact dependence wherein host-pathogen interactions trigger effector protein delivery and serve as an inducing signal for T3SS gene expression. In addition to these conserved features, there are pathogen-specific properties that include a unique repertoire of effector genes and mechanisms to control T3SS gene expression. The Pseudomonas aeruginosa T3SS serves as a model system to understand transcriptional and posttranscriptional mechanisms involved in the control of T3SS gene expression. The central regulatory feature is a partner-switching system that controls the DNA-binding activity of ExsA, the primary regulator of T3SS gene expression. Superimposed upon the partner-switching mechanism are cyclic AMP and cyclic di-GMP signaling systems, two-component systems, global regulators, and RNA-binding proteins that have positive and negative effects on ExsA transcription and/or synthesis. In the present review, we discuss advances in our understanding of how these regulatory systems orchestrate the activation of T3SS gene expression in the context of acute infections and repression of the T3SS as P. aeruginosa adapts to and colonizes the cystic fibrosis airways.
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11
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Liu Y, Wang Z, Bilal M, Hu H, Wang W, Huang X, Peng H, Zhang X. Enhanced Fluorescent Siderophore Biosynthesis and Loss of Phenazine-1-Carboxamide in Phenotypic Variant of Pseudomonas chlororaphis HT66. Front Microbiol 2018; 9:759. [PMID: 29740409 PMCID: PMC5924801 DOI: 10.3389/fmicb.2018.00759] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2017] [Accepted: 04/04/2018] [Indexed: 11/17/2022] Open
Abstract
Pseudomonas chlororaphis HT66 is a plant-beneficial bacterium that exhibits wider antagonistic spectrum against a variety of plant pathogenic fungi due to its main secondary metabolite, i.e., phenazine-1-carboxamide (PCN). In the present study, a spontaneous phenotypic variant designated as HT66-FLUO was isolated from the fermentation process of wild-type HT66 strain. The newly isolated phenotypic variant was morphologically distinct from the wild-type strain such as larger cell size, semi-transparent, non-production of PCN (Green or yellow crystals) and enhanced fluorescence under UV light. The whole-genome, RNA-sequencing, and phenotypic assays were performed to identify the reason of phenotypic variation in HT66-FLUO as compared to the HT66. Transcriptomic analysis revealed that 1,418 genes, representing approximately 22% of the 6393 open reading frames (ORFs) had undergone substantial reprogramming of gene expression in the HT66-FLUO. The whole-genome sequence indicated no gene alteration in HT66-FLUO as compared to HT66 according to the known reference sequence. The levels of global regulatory factor gacA and gacS expression were not significantly different between HT66 and HT66-FLUO. It was observed that overexpressing gacS rather than gacA in HT66-FLUO can recover switching of the variant to HT66. The β-galactosidase (LacZ) activity and qRT-PCR results indicate the downregulated expression of rsmX, rsmY, and rsmZ in HT66-FLUO as compared to HT66. Overexpressing three small RNAs in HT66-FLUO can revert switching of colony phenotype toward wild-type HT66 up to a certain degree, restore partial PCN production and reduces the fluorescent siderophores yield. However, the origin of the spontaneous phenotypic variant was difficult to be determined. In conclusion, this study helps to understand the gene regulatory effect in the spontaneous phenotypic variant.
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Affiliation(s)
- Yang Liu
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Zheng Wang
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Muhammad Bilal
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Hongbo Hu
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China.,National Experimental Teaching Center for Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Wei Wang
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Xianqing Huang
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Huasong Peng
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Xuehong Zhang
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
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12
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Lu P, Wang Y, Hu Y, Chen S. RgsA, an RpoS-dependent sRNA, negatively regulates rpoS expression in Pseudomonas aeruginosa. MICROBIOLOGY-SGM 2018; 164:716-724. [PMID: 29473822 DOI: 10.1099/mic.0.000632] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
As a master regulator, the alternative sigma factor RpoS coordinates the transcription of genes associated with protection against environmental stresses in bacteria. In Pseudomonas aeruginosa, RpoS is also involved in quorum sensing and virulence. The cellular RpoS level is regulated at multiple levels, whereas the post-transcriptional regulation of rpoS in P. aeruginosa remains unclear. To identify and characterize small regulatory RNAs (sRNAs) regulating RpoS in P. aeruginosa, an sRNA library expressing a total of 263 sRNAs was constructed to examine their regulatory roles on rpoS expression. Our results demonstrate that rpoS expression is repressed by the RpoS-dependent sRNA RgsA at the post-transcriptional level. Unlike OxyS, an sRNA previously known to repress rpoS expression under oxidative stress in Escherichia coli, RgsA represses rpoS expression during the exponential phase. This repression requires the RNA chaperone Hfq. Furthermore, the 71-77 conserved region of RgsA is necessary for full repression of rpoS expression, and the -25 to +27 region of rpoS mRNA is sufficient for RgsA-mediated rpoS repression. Together, our results not only add RgsA to the RpoS regulatory circuits but also highlight the complexity of interplay between sRNAs and transcriptional regulators in bacteria.
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Affiliation(s)
- Pei Lu
- Key Laboratory of Special Pathogens and Biosafety, Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, PR China
| | - Yifei Wang
- Key Laboratory of Special Pathogens and Biosafety, Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, PR China
| | - Yangbo Hu
- Key Laboratory of Special Pathogens and Biosafety, Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, PR China
| | - Shiyun Chen
- Key Laboratory of Special Pathogens and Biosafety, Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, PR China
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13
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Fuli X, Wenlong Z, Xiao W, Jing Z, Baohai H, Zhengzheng Z, Bin-Guang M, Youguo L. A Genome-Wide Prediction and Identification of Intergenic Small RNAs by Comparative Analysis in Mesorhizobium huakuii 7653R. Front Microbiol 2017; 8:1730. [PMID: 28943874 PMCID: PMC5596092 DOI: 10.3389/fmicb.2017.01730] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2017] [Accepted: 08/24/2017] [Indexed: 01/23/2023] Open
Abstract
In bacteria, small non-coding RNAs (sRNAs) are critical regulators of cellular adaptation to changes in metabolism, physiology, or the external environment. In the last decade, more than 2000 of sRNA families have been reported in the Rfam database and have been shown to exert various regulatory functions in bacterial transcription and translation. However, little is known about sRNAs and their functions in Mesorhizobium. Here, we predicted putative sRNAs in the intergenic regions (IGRs) of M. huakuii 7653R by genome-wide comparisons with four related Mesorhizobial strains. The expression and transcribed regions of candidate sRNAs were analyzed using a set of high-throughput RNA deep sequencing data. In all, 39 candidate sRNAs were found, with 5 located in the symbiotic megaplasmids and 34 in the chromosome of M. huakuii 7653R. Of these, 24 were annotated as functional sRNAs in the Rfam database and 15 were recognized as putative novel sRNAs. The expression of nine selected sRNAs was confirmed by Northern blotting, and most of the nine selected sRNAs were highly expressed in 28 dpi nodules and under symbiosis-mimicking conditions. For those putative novel sRNAs, functional categorizations of their target genes were performed by analyzing the enriched GO terms. In addition, MH_s15 was shown to be an abundant and conserved sRNA.
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Affiliation(s)
- Xie Fuli
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural UniversityWuhan, China
| | - Zhao Wenlong
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural UniversityWuhan, China
| | - Wang Xiao
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural UniversityWuhan, China
| | - Zhang Jing
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural UniversityWuhan, China
| | - Hao Baohai
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural UniversityWuhan, China
| | - Zou Zhengzheng
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural UniversityWuhan, China
| | - Ma Bin-Guang
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural UniversityWuhan, China
| | - Li Youguo
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural UniversityWuhan, China
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RsmA and AmrZ orchestrate the assembly of all three type VI secretion systems in Pseudomonas aeruginosa. Proc Natl Acad Sci U S A 2017; 114:7707-7712. [PMID: 28673999 DOI: 10.1073/pnas.1700286114] [Citation(s) in RCA: 107] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The type VI secretion system (T6SS) is a weapon of bacterial warfare and host cell subversion. The Gram-negative pathogen Pseudomonas aeruginosa has three T6SSs involved in colonization, competition, and full virulence. H1-T6SS is a molecular gun firing seven toxins, Tse1-Tse7, challenging survival of other bacteria and helping P. aeruginosa to prevail in specific niches. The H1-T6SS characterization was facilitated through studying a P. aeruginosa strain lacking the RetS sensor, which has a fully active H1-T6SS, in contrast to the parent. However, study of H2-T6SS and H3-T6SS has been neglected because of a poor understanding of the associated regulatory network. Here we performed a screen to identify H2-T6SS and H3-T6SS regulatory elements and found that the posttranscriptional regulator RsmA imposes a concerted repression on all three T6SS clusters. A higher level of complexity could be observed as we identified a transcriptional regulator, AmrZ, which acts as a negative regulator of H2-T6SS. Overall, although the level of T6SS transcripts is fine-tuned by AmrZ, all T6SS mRNAs are silenced by RsmA. We expanded this concept of global control by RsmA to VgrG spike and T6SS toxin transcripts whose genes are scattered on the chromosome. These observations triggered the characterization of a suite of H2-T6SS toxins and their implication in direct bacterial competition. Our study thus unveils a central mechanism that modulates the deployment of all T6SS weapons that may be simultaneously produced within a single cell.
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15
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Deng X, Li M, Pan X, Zheng R, Liu C, Chen F, Liu X, Cheng Z, Jin S, Wu W. Fis Regulates Type III Secretion System by Influencing the Transcription of exsA in Pseudomonas aeruginosa Strain PA14. Front Microbiol 2017; 8:669. [PMID: 28469612 PMCID: PMC5395579 DOI: 10.3389/fmicb.2017.00669] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2017] [Accepted: 03/31/2017] [Indexed: 11/21/2022] Open
Abstract
Fis is a versatile DNA binding protein in bacteria. It has been demonstrated in multiple bacteria that Fis plays crucial roles in regulating bacterial virulence factors and optimizing bacterial adaptation to various environments. However, the role of Fis in Pseudomonas aeruginosa virulence as well as gene regulation remains largely unknown. Here, we found that Fis was required for the virulence of P. aeruginosa in a murine acute pneumonia model. Transcriptome analysis revealed that expression of T3SS genes, including master regulator ExsA, was defective in a fis::Tn mutant. We further demonstrate that the continuous transcription of exsC, exsE, exsB, and exsA driven by the exsC promoter was required for the activation of T3SS. Fis was found to specifically bind to the exsB-exsA intergenic region and plays an essential role in the transcription elongation from exsB to exsA. Therefore, we found a novel role of Fis in the regulation of exsA expression.
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Affiliation(s)
- Xuan Deng
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai UniversityTianjin, China
| | - Mei Li
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai UniversityTianjin, China
| | - Xiaolei Pan
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai UniversityTianjin, China
| | - Ruiping Zheng
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai UniversityTianjin, China
| | - Chang Liu
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai UniversityTianjin, China
| | - Fei Chen
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai UniversityTianjin, China
| | - Xue Liu
- State Key Laboratory of Medicinal Chemical Biology, College of Life Sciences, Nankai UniversityTianjin, China
| | - Zhihui Cheng
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai UniversityTianjin, China
| | - Shouguang Jin
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai UniversityTianjin, China.,Department of Molecular Genetics and Microbiology, College of Medicine, University of FloridaGainesville, FL, USA
| | - Weihui Wu
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai UniversityTianjin, China
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16
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Small RNAs regulate the biocontrol property of fluorescent Pseudomonas strain Psd. Microbiol Res 2017; 196:80-88. [DOI: 10.1016/j.micres.2016.12.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2016] [Revised: 10/19/2016] [Accepted: 12/18/2016] [Indexed: 01/11/2023]
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17
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Miller CL, Van Laar TA, Chen T, Karna SLR, Chen P, You T, Leung KP. Global transcriptome responses including small RNAs during mixed-species interactions with methicillin-resistant Staphylococcus aureus and Pseudomonas aeruginosa. Microbiologyopen 2016; 6. [PMID: 27868360 PMCID: PMC5458535 DOI: 10.1002/mbo3.427] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Revised: 10/11/2016] [Accepted: 10/13/2016] [Indexed: 12/27/2022] Open
Abstract
Pseudomonas aeruginosa and Staphylococcus aureus mixed‐species biofilm infections are more resilient to biocide attacks compared to their single‐species counterparts. Therefore, this study used an in vitro model recapitulating bacterial burdens seen in in vivo infections to investigate the interactions of P. aeruginosa and S. aureus in biofilms. RNA sequencing (RNA‐seq) was utilized to identify the entire genomic response, both open reading frames (ORFs) and small RNAs (sRNAs), of each species. Using competitive indexes, transposon mutants validated uncharacterized PA1595 of P. aeruginosa and Panton–Valentine leukocidin ORFs of S. aureus are required for competitive success. Assessing spent media on biofilm development determined that the effects of these ORFs are not solely mediated by mechanisms of secretion. Unlike PA1595, leukocidin (lukS‐PV) mutants of S. aureus lack a competitive advantage through contact‐mediated mechanisms demonstrated by cross‐hatch assays. RNA‐seq results suggested that during planktonic mixed‐species growth there is a robust genomic response or active combat from both pathogens until a state of equilibrium is reached during the maturation of a biofilm. In mixed‐species biofilms, P. aeruginosa differentially expressed only 0.3% of its genome, with most ORFs necessary for growth and biofilm development, whereas S. aureus modulated approximately 5% of its genome, with ORFs suggestive of a phenotype of increased virulence and metabolic quiescence. Specific expression of characterized sRNAs aligned with the genomic response to presumably coordinate the adaptive changes necessary for this homeostatic mixed‐species biofilm and sRNAs may provide viable foci for the design of future therapeutics.
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Affiliation(s)
- Christine L Miller
- Microbiology Branch, Dental and Craniofacial Trauma Research and Tissue Regeneration Directorate, Institute of Surgical Research, JBSA Fort Sam Houston, TX, USA
| | - Tricia A Van Laar
- Microbiology Branch, Dental and Craniofacial Trauma Research and Tissue Regeneration Directorate, Institute of Surgical Research, JBSA Fort Sam Houston, TX, USA
| | - Tsute Chen
- The Forsyth Institute, Cambridge, MA, USA
| | - S L Rajasekhar Karna
- Microbiology Branch, Dental and Craniofacial Trauma Research and Tissue Regeneration Directorate, Institute of Surgical Research, JBSA Fort Sam Houston, TX, USA
| | - Ping Chen
- Microbiology Branch, Dental and Craniofacial Trauma Research and Tissue Regeneration Directorate, Institute of Surgical Research, JBSA Fort Sam Houston, TX, USA
| | - Tao You
- Microbiology Branch, Dental and Craniofacial Trauma Research and Tissue Regeneration Directorate, Institute of Surgical Research, JBSA Fort Sam Houston, TX, USA
| | - Kai P Leung
- Microbiology Branch, Dental and Craniofacial Trauma Research and Tissue Regeneration Directorate, Institute of Surgical Research, JBSA Fort Sam Houston, TX, USA
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18
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Lee K, Ha GS, Veeranagouda Y, Seo YS, Hwang I. A CHASE3/GAF sensor hybrid histidine kinase BmsA modulates biofilm formation and motility in Pseudomonas alkylphenolica. MICROBIOLOGY-SGM 2016; 162:1945-1954. [PMID: 27655385 DOI: 10.1099/mic.0.000373] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Pseudomonas alkylphenolica is an important strain in the biodegradation of toxic alkylphenols and mass production of bioactive polymannuronate polymers. This strain forms a diverse, 3D biofilm architecture, including mushroom-like aerial structures, circular pellicles and surface spreading, depending on culture conditions. A mutagenesis and complementation study showed that a predicted transmembrane kinase, PSAKL28_21690 (1164 aa), harbouring a periplasmic CHASE3 domain flanked by two transmembrane helices in addition to its cytoplasmic GAF, histidine kinase and three CheY-like response regulator domains, plays a positive role in the formation of the special biofilm architecture and a negative role in swimming activity. In addition, the gene, named here as bmsA, is co-transcribed with three genes encoding proteins with CheR (PSAKL28_21700) and CheB (PSAKL28_21710) domains and response regulator and histidine kinase domains (PSAKL28_21720). This gene cluster is thus named bmsABCD and is found widely distributed in pseudomonads and other bacteria. Deletion of the genes in the cluster, except forbmsA, did not result in changes in biofilm-related phenotypes. The RNA-seq analysis showed that the expression of genes coding for flagellar synthesis was increased when bmsA was mutated. In addition, the expression of rsmZ, which is one of final targets of the Gac regulon, was not significantly altered in the bmsA mutant, and overexpression of bmsA in the gacA mutant did not produce the WT phenotype. These results indicate that the sensory Bms regulon does not affect the upper cascade of the Gac signal transduction pathway for the biofilm-related phenotypes in P. alkylphenolica.
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Affiliation(s)
- Kyoung Lee
- Department of Bio Health Science, Changwon National University, Changwon-si, Kyongnam 51140, Republic of Korea
| | - Gwang Su Ha
- Department of Bio Health Science, Changwon National University, Changwon-si, Kyongnam 51140, Republic of Korea
| | - Yaligara Veeranagouda
- Department of Bio Health Science, Changwon National University, Changwon-si, Kyongnam 51140, Republic of Korea
| | - Young-Su Seo
- Department of Microbiology, Pusan National University, Busan 46241, Republic of Korea
| | - Ingyu Hwang
- Department of Agricultural Biotechnology, Seoul National University, Seoul 08826, Republic of Korea
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19
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Lu P, Wang Y, Zhang Y, Hu Y, Thompson KM, Chen S. RpoS-dependent sRNA RgsA regulates Fis and AcpP in Pseudomonas aeruginosa. Mol Microbiol 2016; 102:244-259. [PMID: 27381272 DOI: 10.1111/mmi.13458] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/02/2016] [Indexed: 12/01/2022]
Abstract
RgsA is a phylogenetically conserved small regulatory RNA (sRNA) in Pseudomonas species. This sRNA has been shown to be directly controlled by the major stationary phase and stress sigma factor σS (RpoS), and also indirectly regulated by the GacS/GacA two-component system. However, the role and the regulatory targets of this sRNA remain unclear. Here, two direct regulatory targets of RgsA, the mRNAs coding for the global transcriptional regulator Fis and the acyl carrier protein AcpP, were identified in P. aeruginosa. RgsA downregulates the synthesis of Fis and AcpP by base-pairing, and this regulation requires the RNA chaperone protein Hfq. Alignment of RgsA homologs in Pseudomonas revealed a conserved core region, which is strictly required for RgsA target recognition. Specifically, RgsA inhibits fis expression via an 11 + 11 bp RNA duplex, whereas this interaction region is not sufficient for repression and the 35 nt downstream region is also required. Interestingly, two functional start codons initiate fis mRNA translation and both are repressed by RgsA. Furthermore, deletion of rgsA significantly increased swarming motility in P. aeruginosa. Together, this study suggests a novel regulatory role of sRNA in which the versatile transcriptional regulator Fis and the stress regulator RpoS are connected by RgsA.
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Affiliation(s)
- Pei Lu
- Key Laboratory of Special Pathogens and Biosafety, Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China
| | - Yifei Wang
- Key Laboratory of Special Pathogens and Biosafety, Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China
| | - Yong Zhang
- Key Laboratory of Special Pathogens and Biosafety, Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China
| | - Yangbo Hu
- Key Laboratory of Special Pathogens and Biosafety, Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China
| | - Karl M Thompson
- Department of Microbiology, College of Medicine, Howard University, Washington, DC, 20059, USA
| | - Shiyun Chen
- Key Laboratory of Special Pathogens and Biosafety, Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China.
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20
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Huerta JM, Aguilar I, López-Pliego L, Fuentes-Ramírez LE, Castañeda M. The Role of the ncRNA RgsA in the Oxidative Stress Response and Biofilm Formation in Azotobacter vinelandii. Curr Microbiol 2016; 72:671-9. [PMID: 26858204 DOI: 10.1007/s00284-016-1003-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2015] [Accepted: 12/27/2015] [Indexed: 12/23/2022]
Abstract
Azotobacter vinelandii is a soil bacterium that forms desiccation-resistant cysts, and the exopolysaccharide alginate is essential for this process. A. vinelandii also produces alginate under vegetative growth conditions, and this production has biotechnological significance. Poly-β-hydroxybutyrate (PHB) is another polymer synthetized by A. vinelandii that is of biotechnological interest. The GacS/A two-component signal transduction system plays an important role in regulating alginate production, PHB synthesis, and encystment. GacS/A in turn controls other important regulators such as RpoS and the ncRNAs that belong to the Rsm family. In A. vinelandii, RpoS is necessary for resisting oxidative stress as a result of its control over the expression of the catalase Kat1. In this work, we characterized a new ncRNA in A. vinelandii that is homologous to the P16/RsgA reported in Pseudomonas. We found that the expression of rgsA is regulated by GacA and RpoS and that it was essential for oxidative stress resistance. However, the activity of the catalase Kat1 is unaffected in rgsA mutants. Unlike those reported in Pseudomonas, RgsA in A. vinelandii regulates biofilm formation but not polymer synthesis or the encystment process.
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Affiliation(s)
- Jesús Manuel Huerta
- CICM-Instituto de Ciencias, Benemérita Universidad Autónoma de Puebla, Puebla, Mexico
| | - Israel Aguilar
- CICM-Instituto de Ciencias, Benemérita Universidad Autónoma de Puebla, Puebla, Mexico
| | - Liliana López-Pliego
- CICM-Instituto de Ciencias, Benemérita Universidad Autónoma de Puebla, Puebla, Mexico
| | | | - Miguel Castañeda
- CICM-Instituto de Ciencias, Benemérita Universidad Autónoma de Puebla, Puebla, Mexico.
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21
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Chen Y, Yuan M, Mohanty A, Yam JKH, Liu Y, Chua SL, Nielsen TE, Tolker-Nielsen T, Givskov M, Cao B, Yang L. Multiple diguanylate cyclase-coordinated regulation of pyoverdine synthesis in Pseudomonas aeruginosa. ENVIRONMENTAL MICROBIOLOGY REPORTS 2015; 7:498-507. [PMID: 25683454 DOI: 10.1111/1758-2229.12278] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2014] [Accepted: 01/30/2015] [Indexed: 06/04/2023]
Abstract
The nucleotide signalling molecule bis-(3'-5')-cyclic dimeric guanosine monophosphate (c-di-GMP) plays an essential role in regulating microbial virulence and biofilm formation. C-di-GMP is synthesized by diguanylate cyclase (DGC) enzymes and degraded by phosphodiesterase (PDE) enzymes. One intrinsic feature of c-di-GMP signalling is the abundance of DGCs and PDEs encoded by many bacterial species. It is unclear whether the different DGCs or PDEs coordinately establish the c-di-GMP regulation or function independently of each other. Here, we provide evidence that multiple DGCs are involved in regulation of c-di-GMP on synthesis of the major iron siderophore pyoverdine in Pseudomonas aeruginosa. Constitutive expression of the WspG or YedQ DGC in P. aeruginosa is able to induce its pyoverdine synthesis. Induction of pyoverdine synthesis by high intracellular c-di-GMP depends on the synthesis of exopolysaccharides and another two DGCs, SiaD and SadC. SiaD was found to boost the c-di-GMP synthesis together with constitutively expressing YedQ. The exopolysaccharides and the SiaD DGC were found to modulate the expression of the RsmY/RsmZ ncRNAs. Induction of the RsmY/RsmZ ncRNAs might enhance the pyoverdine synthesis through SadC. Our study sheds light on a novel multiple DGC-coordinated c-di-GMP regulatory mechanism of bacteria.
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Affiliation(s)
- Yicai Chen
- Singapore Centre on Environmental Life Sciences Engineering (SCELSE), Nanyang Technological University, Nanyang, 637551, Singapore
| | - Mingjun Yuan
- Singapore Centre on Environmental Life Sciences Engineering (SCELSE), Nanyang Technological University, Nanyang, 637551, Singapore
| | - Anee Mohanty
- School of Civil and Environmental Engineering, Nanyang Technological University, Nanyang, 639798, Singapore
| | - Joey Kuok Hoong Yam
- Singapore Centre on Environmental Life Sciences Engineering (SCELSE), Nanyang Technological University, Nanyang, 637551, Singapore
- Interdisciplinary Graduate School, Nanyang Technological University, Nanyang, 637551, Singapore
| | - Yang Liu
- Singapore Centre on Environmental Life Sciences Engineering (SCELSE), Nanyang Technological University, Nanyang, 637551, Singapore
| | - Song Lin Chua
- Singapore Centre on Environmental Life Sciences Engineering (SCELSE), Nanyang Technological University, Nanyang, 637551, Singapore
- NUS Graduate School of Integrative Sciences and Engineering, National University of Singapore, Nanyang, 117543, Singapore
| | - Thomas E Nielsen
- Department of Chemistry, Technical University of Denmark, Kgs. Lyngby, DK-2800, Denmark
| | - Tim Tolker-Nielsen
- Costerton Biofilm Center, Department of International Health, Immunology and Microbiology, Panum Institute, University of Copenhagen, København N, 2200, Denmark
| | - Michael Givskov
- Singapore Centre on Environmental Life Sciences Engineering (SCELSE), Nanyang Technological University, Nanyang, 637551, Singapore
- Costerton Biofilm Center, Department of International Health, Immunology and Microbiology, Panum Institute, University of Copenhagen, København N, 2200, Denmark
| | - Bin Cao
- Singapore Centre on Environmental Life Sciences Engineering (SCELSE), Nanyang Technological University, Nanyang, 637551, Singapore
- School of Civil and Environmental Engineering, Nanyang Technological University, Nanyang, 639798, Singapore
| | - Liang Yang
- Singapore Centre on Environmental Life Sciences Engineering (SCELSE), Nanyang Technological University, Nanyang, 637551, Singapore
- School of Biological Sciences, Nanyang Technological University, Nanyang, 639798, Singapore
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22
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Gómez-Lozano M, Marvig RL, Molina-Santiago C, Tribelli PM, Ramos JL, Molin S. Diversity of small RNAs expressed in Pseudomonas species. ENVIRONMENTAL MICROBIOLOGY REPORTS 2015; 7:227-236. [PMID: 25394275 DOI: 10.1111/1758-2229.12233] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2014] [Revised: 10/18/2014] [Accepted: 10/28/2014] [Indexed: 06/04/2023]
Abstract
RNA sequencing (RNA-seq) has revealed several hundreds of previously undetected small RNAs (sRNAs) in all bacterial species investigated, including strains of Pseudomonas aeruginosa, Pseudomonas putida and Pseudomonas syringae. Nonetheless, only little is known about the extent of conservation of expressed sRNAs across strains and species. In this study, we have used RNA-seq to identify sRNAs in P. putida DOT-T1E and Pseudomonas extremaustralis 14-3b. This is the first strain of P. extremaustralis and the second strain of P. putida to have their transcriptomes analysed for sRNAs, and we identify the presence of around 150 novel sRNAs in each strain. Furthermore, we provide a comparison based on sequence conservation of all the sRNAs detected by RNA-seq in the Pseudomonas species investigated so far. Our results show that the extent of sRNA conservation across different species is very limited. In addition, when comparing the sRNAs expressed in different strains of the same species, we observe that numerous sRNAs exhibit a strain-specific expression pattern. These results support the idea that the evolution of most bacterial sRNAs is rapid, which limits the extent of both interspecies and intraspecies conservation.
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Affiliation(s)
- María Gómez-Lozano
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Hørsholm, DK-2970, Denmark
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23
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Balasubramanian D, Kumari H, Mathee K. Pseudomonas aeruginosa AmpR: an acute-chronic switch regulator. Pathog Dis 2015; 73:1-14. [PMID: 25066236 DOI: 10.1111/2049-632x.12208] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Pseudomonas aeruginosa is one of the most intractable human pathogens that pose serious clinical challenge due to extensive prevalence of multidrug-resistant clinical isolates. Armed with abundant virulence and antibiotic resistance mechanisms, it is a major etiologic agent in a number of acute and chronic infections. A complex and intricate network of regulators dictates the expression of pathogenicity factors in P. aeruginosa. Some proteins within the network play key roles and control multiple pathways. This review discusses the role of one such protein, AmpR, which was initially recognized for its role in antibiotic resistance by regulating AmpC β-lactamase. Recent genomic, proteomic and phenotypic analyses demonstrate that AmpR regulates expression of hundreds of genes that are involved in diverse pathways such as β-lactam and non-β-lactam resistance, quorum sensing and associated virulence phenotypes, protein phosphorylation, and physiological processes. Finally, ampR mutations in clinical isolates are reviewed to shed light on important residues required for its function in antibiotic resistance. The prevalence and evolutionary implications of AmpR in pathogenic and nonpathogenic proteobacteria are also discussed. A comprehensive understanding of proteins at nodal positions in the P. aeruginosa regulatory network is crucial in understanding, and ultimately targeting, the pathogenic stratagems of this organism.
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Affiliation(s)
| | - Hansi Kumari
- Department of Human & Molecular Genetics, Herbert Wertheim College of Medicine, Florida International University, Miami, FL, USA
| | - Kalai Mathee
- Department of Human & Molecular Genetics, Herbert Wertheim College of Medicine, Florida International University, Miami, FL, USA
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24
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Song C, van der Voort M, van de Mortel J, Hassan KA, Elbourne LDH, Paulsen IT, Loper JE, Raaijmakers JM. The Rsm regulon of plant growth-promoting Pseudomonas fluorescens SS101: role of small RNAs in regulation of lipopeptide biosynthesis. Microb Biotechnol 2014; 8:296-310. [PMID: 25488342 PMCID: PMC4353343 DOI: 10.1111/1751-7915.12190] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Revised: 09/29/2014] [Accepted: 10/02/2014] [Indexed: 11/28/2022] Open
Abstract
The rhizobacterium Pseudomonas fluorescens SS101 inhibits growth of oomycete and fungal pathogens, and induces resistance in plants against pathogens and insects. To unravel regulatory pathways of secondary metabolite production in SS101, we conducted a genome-wide search for sRNAs and performed transcriptomic analyses to identify genes associated with the Rsm (repressor of secondary metabolites) regulon. In silico analysis led to the identification of 16 putative sRNAs in the SS101 genome. In frame deletion of the sRNAs rsmY and rsmZ showed that the Rsm system regulates the biosynthesis of the lipopeptide massetolide A and involves the two repressor proteins RsmA and RsmE, with the LuxR-type transcriptional regulator MassAR as their most likely target. Transcriptome analyses of the rsmYZ mutant further revealed that genes associated with iron acquisition, motility and chemotaxis were significantly upregulated, whereas genes of the type VI secretion system were downregulated. Comparative transcriptomic analyses showed that most, but not all, of the genes controlled by RsmY/RsmZ are also controlled by the GacS/GacA two-component system. We conclude that the Rsm regulon of P. fluorescens SS101 plays a critical role in the regulation of lipopeptide biosynthesis and controls the expression of other genes involved in motility, competition and survival in the plant rhizosphere.
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Affiliation(s)
- Chunxu Song
- Laboratory of Phytopathology, Wageningen University, 6708 PD, Wageningen, the Netherlands; Department of Microbial Ecology, Netherlands Institute of Ecology, 6708 PB, Wageningen, the Netherlands
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Transcriptional analysis of the global regulatory networks active in Pseudomonas syringae during leaf colonization. mBio 2014; 5:e01683-14. [PMID: 25182327 PMCID: PMC4173789 DOI: 10.1128/mbio.01683-14] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The plant pathogen Pseudomonas syringae pv. syringae B728a grows and survives on leaf surfaces and in the leaf apoplast of its host, bean (Phaseolus vulgaris). To understand the contribution of distinct regulators to B728a fitness and pathogenicity, we performed a transcriptome analysis of strain B728a and nine regulatory mutants recovered from the surfaces and interior of leaves and exposed to environmental stresses in culture. The quorum-sensing regulators AhlR and AefR influenced few genes in planta or in vitro. In contrast, GacS and a downstream regulator, SalA, formed a large regulatory network that included a branch that regulated diverse traits and was independent of plant-specific environmental signals and a plant signal-dependent branch that positively regulated secondary metabolite genes and negatively regulated the type III secretion system. SalA functioned as a central regulator of iron status based on its reciprocal regulation of pyoverdine and achromobactin genes and also sulfur uptake, suggesting a role in the iron-sulfur balance. RetS functioned almost exclusively to repress secondary metabolite genes when the cells were not on leaves. Among the sigma factors examined, AlgU influenced many more genes than RpoS, and most AlgU-regulated genes depended on RpoN. RpoN differentially impacted many AlgU- and GacS-activated genes in cells recovered from apoplastic versus epiphytic sites, suggesting differences in environmental signals or bacterial stress status in these two habitats. Collectively, our findings illustrate a central role for GacS, SalA, RpoN, and AlgU in global regulation in B728a in planta and a high level of plasticity in these regulators’ responses to distinct environmental signals. Leaves harbor abundant microorganisms, all of which must withstand challenges such as active plant defenses and a highly dynamic environment. Some of these microbes can influence plant health. Despite knowledge of individual regulators that affect the fitness or pathogenicity of foliar pathogens, our understanding of the relative importance of various global regulators to leaf colonization is limited. Pseudomonas syringae strain B728a is a plant pathogen and a good colonist of both the surfaces and interior of leaves. This study used global transcript profiles of strain B728a to investigate the complex regulatory network of putative quorum-sensing regulators, two-component regulators, and sigma factors in cells colonizing the leaf surface and leaf interior under stressful in vitro conditions. The results highlighted the value of evaluating these networks in planta due to the impact of leaf-specific environmental signals and suggested signal differences that may enable cells to differentiate surface versus interior leaf habitats.
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The two-component GacS-GacA system activates lipA translation by RsmE but not RsmA in Pseudomonas protegens Pf-5. Appl Environ Microbiol 2014; 80:6627-37. [PMID: 25128345 DOI: 10.1128/aem.02184-14] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In Pseudomonas spp., the Gac-Rsm signal transduction system is required for the production of lipases. The current model assumes that the system induces lipase gene transcription mediated through the quorum-sensing (QS) system. However, there are no reports of a QS system based upon N-acyl homoserine lactones or the regulation of lipase gene expression in Pseudomonas protegens. In this study, we investigated the regulatory mechanism acting on lipA expression activated by the Gac-Rsm system in P. protegens Pf-5 through deletion and overexpression of gacA, overexpression of rsmA or rsmE, expression of various lacZ fusions, reverse transcription-PCR analysis, and determination of whole-cell lipase activity. The results demonstrated that the GacS-GacA (GacS/A) system activates lipA expression at both the transcriptional and the translational levels but that the translational level is the key regulatory pathway. Further results showed that the activation of lipA translation by the GacS/A system is mediated through RsmE, which inhibits lipA translation by binding to the ACAAGGAUGU sequence overlapping the Shine-Dalgarno (SD) sequence of lipA mRNA to hinder the access of the 30S ribosomal subunit to the SD sequence. Moreover, the GacS/A system promotes lipA transcription through the mediation of RsmA inhibiting lipA transcription via an unknown pathway. Besides the transcriptional repression, RsmA mainly activates lipA translation by negatively regulating rsmE translation. In summary, in P. protegens Pf-5, the Gac-RsmE system mainly and directly activates lipA translation and the Gac-RsmA system indirectly enhances lipA transcription.
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Wenner N, Maes A, Cotado-Sampayo M, Lapouge K. NrsZ: a novel, processed, nitrogen-dependent, small non-coding RNA that regulates Pseudomonas aeruginosa PAO1 virulence. Environ Microbiol 2014; 16:1053-68. [PMID: 24308329 PMCID: PMC4253122 DOI: 10.1111/1462-2920.12272] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2013] [Revised: 08/26/2013] [Accepted: 08/28/2013] [Indexed: 12/11/2022]
Abstract
The opportunistic pathogen Pseudomonas aeruginosa PAO1 has a remarkable capacity to adapt to various environments and to survive with limited nutrients. Here, we report the discovery and characterization of a novel small non-coding RNA: NrsZ (nitrogen-regulated sRNA). We show that under nitrogen limitation, NrsZ is induced by the NtrB/C two component system, an important regulator of nitrogen assimilation and P. aeruginosa's swarming motility, in concert with the alternative sigma factor RpoN. Furthermore, we demonstrate that NrsZ modulates P. aeruginosa motility by controlling the production of rhamnolipid surfactants, virulence factors notably needed for swarming motility. This regulation takes place through the post-transcriptional control of rhlA, a gene essential for rhamnolipids synthesis. Interestingly, we also observed that NrsZ is processed in three similar short modules, and that the first short module encompassing the first 60 nucleotides is sufficient for NrsZ regulatory functions.
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Affiliation(s)
- Nicolas Wenner
- Department of Fundamental Microbiology, University of LausanneLausanne, CH-1015, Switzerland
| | - Alexandre Maes
- Department of Fundamental Microbiology, University of LausanneLausanne, CH-1015, Switzerland
| | - Marta Cotado-Sampayo
- Fasteris SACh. du Pont-du-Centenaire 109, Case postale 28, Plan-les-Ouates, CH-1228, Switzerland
| | - Karine Lapouge
- Department of Fundamental Microbiology, University of LausanneLausanne, CH-1015, Switzerland
- *For correspondence. E-mail ; Tel. (+41) (0) 21 692 5601; Fax (+41) (0) 21 692 5605
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Kwon T, Huse HK, Vogel C, Whiteley M, Marcotte EM. Protein-to-mRNA ratios are conserved between Pseudomonas aeruginosa strains. J Proteome Res 2014; 13:2370-80. [PMID: 24742327 PMCID: PMC4012837 DOI: 10.1021/pr4011684] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Recent studies have shown that the concentrations of proteins expressed from orthologous genes are often conserved across organisms and to a greater extent than the abundances of the corresponding mRNAs. However, such studies have not distinguished between evolutionary (e.g., sequence divergence) and environmental (e.g., growth condition) effects on the regulation of steady-state protein and mRNA abundances. Here, we systematically investigated the transcriptome and proteome of two closely related Pseudomonas aeruginosa strains, PAO1 and PA14, under identical experimental conditions, thus controlling for environmental effects. For 703 genes observed by both shotgun proteomics and microarray experiments, we found that the protein-to-mRNA ratios are highly correlated between orthologous genes in the two strains to an extent comparable to protein and mRNA abundances. In spite of this high molecular similarity between PAO1 and PA14, we found that several metabolic, virulence, and antibiotic resistance genes are differentially expressed between the two strains, mostly at the protein but not at the mRNA level. Our data demonstrate that the magnitude and direction of the effect of protein abundance regulation occurring after the setting of mRNA levels is conserved between bacterial strains and is important for explaining the discordance between mRNA and protein abundances.
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Affiliation(s)
- Taejoon Kwon
- Center for Systems and Synthetic Biology, Institute for Cellular and Molecular Biology, University of Texas at Austin , 2500 Speedway, Austin, Texas 78712, United States
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Michaux C, Verneuil N, Hartke A, Giard JC. Physiological roles of small RNA molecules. MICROBIOLOGY-SGM 2014; 160:1007-1019. [PMID: 24694375 DOI: 10.1099/mic.0.076208-0] [Citation(s) in RCA: 90] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Unlike proteins, RNA molecules have emerged lately as key players in regulation in bacteria. Most reviews hitherto focused on the experimental and/or in silico methods used to identify genes encoding small RNAs (sRNAs) or on the diverse mechanisms of these RNA regulators to modulate expression of their targets. However, less is known about their biological functions and their implications in various physiological responses. This review aims to compile what is known presently about the diverse roles of sRNA transcripts in the regulation of metabolic processes, in different growth conditions, in adaptation to stress and in microbial pathogenesis. Several recent studies revealed that sRNA molecules are implicated in carbon metabolism and transport, amino acid metabolism or metal sensing. Moreover, regulatory RNAs participate in cellular adaptation to environmental changes, e.g. through quorum sensing systems or development of biofilms, and analyses of several sRNAs under various physiological stresses and culture conditions have already been performed. In addition, recent experiments performed with Gram-positive and Gram-negative pathogens showed that regulatory RNAs play important roles in microbial virulence and during infection. The combined results show the diversity of regulation mechanisms and physiological processes in which sRNA molecules are key actors.
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Affiliation(s)
- Charlotte Michaux
- Unité de Recherche Risques Microbiens (U2RM), Equipe Stress Virulence, Université de Caen, 14032 Caen, France
| | - Nicolas Verneuil
- Unité de Recherche Risques Microbiens (U2RM), Equipe Stress Virulence, Université de Caen, 14032 Caen, France
| | - Axel Hartke
- Unité de Recherche Risques Microbiens (U2RM), Equipe Stress Virulence, Université de Caen, 14032 Caen, France
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The phzA2-G2 transcript exhibits direct RsmA-mediated activation in Pseudomonas aeruginosa M18. PLoS One 2014; 9:e89653. [PMID: 24586939 PMCID: PMC3933668 DOI: 10.1371/journal.pone.0089653] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2013] [Accepted: 01/24/2014] [Indexed: 12/30/2022] Open
Abstract
In bacteria, RNA-binding proteins of the RsmA/CsrA family act as post-transcriptional regulators that modulate translation initiation at target transcripts. The Pseudomonas aeruginosa genome contains two phenazine biosynthetic (phz) gene clusters, phzA1-G1 (phz1) and phzA2-G2 (phz2), each of which is responsible for phenazine-1-carboxylic acid (PCA) biosynthesis. In the present study, we show that RsmA exhibits differential gene regulation on two phz clusters in P. aeruginosa M18 at the post-transcriptional level. Based on the sequence analysis, four GGA motifs, the potential RsmA binding sites, are found on the 5'-untranslated region (UTR) of the phz2 transcript. Studies with a series of lacZ reporter fusions, and gel mobility shift assays suggest that the third GGA motif (S3), located 21 nucleotides upstream of the Shine-Dalgarno (SD) sequence, is involved in direct RsmA-mediated activation of phz2 expression. We therefore propose a novel model in which the binding of RsmA to the target S3 results in the destabilization of the stem-loop structure and the enhancement of ribosome access. This model could be fully supported by RNA structure prediction, free energy calculations, and nucleotide replacement studies. In contrast, various RsmA-mediated translation repression mechanisms have been identified in which RsmA binds near the SD sequence of target transcripts, thereby blocking ribosome access. Similarly, RsmA is shown to negatively regulate phz1 expression. Our new findings suggest that the differential regulation exerted by RsmA on the two phz clusters may confer an advantage to P. aeruginosa over other pseudomonads containing only a single phz cluster in their genomes.
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Takeuchi K, Tsuchiya W, Noda N, Suzuki R, Yamazaki T, Haas D. Lon protease negatively affects GacA protein stability and expression of the Gac/Rsm signal transduction pathway inPseudomonas protegens. Environ Microbiol 2014; 16:2538-49. [DOI: 10.1111/1462-2920.12394] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2013] [Revised: 12/24/2013] [Accepted: 01/04/2014] [Indexed: 01/31/2023]
Affiliation(s)
- Kasumi Takeuchi
- Plant-Microbe Interactions Research Unit; National Institute of Agrobiological Sciences; 2-1-2 Kannondai Tsukuba Ibaraki 305-8602 Japan
| | - Wataru Tsuchiya
- Biomolecular Research Unit; National Institute of Agrobiological Sciences; 2-1-2 Kannondai Tsukuba Ibaraki 305-8602 Japan
| | - Naomi Noda
- Plant-Microbe Interactions Research Unit; National Institute of Agrobiological Sciences; 2-1-2 Kannondai Tsukuba Ibaraki 305-8602 Japan
| | - Rintaro Suzuki
- Biomolecular Research Unit; National Institute of Agrobiological Sciences; 2-1-2 Kannondai Tsukuba Ibaraki 305-8602 Japan
| | - Toshimasa Yamazaki
- Biomolecular Research Unit; National Institute of Agrobiological Sciences; 2-1-2 Kannondai Tsukuba Ibaraki 305-8602 Japan
| | - Dieter Haas
- Département de Microbiologie Fondamentale; Université de Lausanne; CH-1015 Lausanne Switzerland
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The global response regulator ExpA controls virulence gene expression through RsmA-mediated and RsmA-independent pathways in Pectobacterium wasabiae SCC3193. Appl Environ Microbiol 2014; 80:1972-84. [PMID: 24441162 DOI: 10.1128/aem.03829-13] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
ExpA (GacA) is a global response regulator that controls the expression of major virulence genes, such as those encoding plant cell wall-degrading enzymes (PCWDEs) in the model soft rot phytopathogen Pectobacterium wasabiae SCC3193. Several studies with pectobacteria as well as related phytopathogenic gammaproteobacteria, such as Dickeya and Pseudomonas, suggest that the control of virulence by ExpA and its homologues is executed partly by modulating the activity of RsmA, an RNA-binding posttranscriptional regulator. To elucidate the extent of the overlap between the ExpA and RsmA regulons in P. wasabiae, we characterized both regulons by microarray analysis. To do this, we compared the transcriptomes of the wild-type strain, an expA mutant, an rsmA mutant, and an expA rsmA double mutant. The microarray data for selected virulence-related genes were confirmed through quantitative reverse transcription (qRT-PCR). Subsequently, assays were performed to link the observed transcriptome differences to changes in bacterial phenotypes such as growth, motility, PCWDE production, and virulence in planta. An extensive overlap between the ExpA and RsmA regulons was observed, suggesting that a substantial portion of ExpA regulation appears to be mediated through RsmA. However, a number of genes involved in the electron transport chain and oligogalacturonide metabolism, among other processes, were identified as being regulated by ExpA independently of RsmA. These results suggest that ExpA may only partially impact fitness and virulence via RsmA.
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Balasubramanian D, Kumari H, Jaric M, Fernandez M, Turner KH, Dove SL, Narasimhan G, Lory S, Mathee K. Deep sequencing analyses expands the Pseudomonas aeruginosa AmpR regulon to include small RNA-mediated regulation of iron acquisition, heat shock and oxidative stress response. Nucleic Acids Res 2013; 42:979-98. [PMID: 24157832 PMCID: PMC3902932 DOI: 10.1093/nar/gkt942] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Pathogenicity of Pseudomonas aeruginosa, a major cause of many acute and chronic human infections, is determined by tightly regulated expression of multiple virulence factors. Quorum sensing (QS) controls expression of many of these pathogenic determinants. Previous microarray studies have shown that the AmpC β-lactamase regulator AmpR, a member of the LysR family of transcription factors, also controls non-β-lactam resistance and multiple virulence mechanisms. Using RNA-Seq and complementary assays, this study further expands the AmpR regulon to include diverse processes such as oxidative stress, heat shock and iron uptake. Importantly, AmpR affects many of these phenotypes, in part, by regulating expression of non-coding RNAs such as rgP32, asRgsA, asPrrF1 and rgRsmZ. AmpR positively regulates expression of the major QS regulators LasR, RhlR and MvfR, and genes of the Pseudomonas quinolone system. Chromatin immunoprecipitation (ChIP)-Seq and ChIP–quantitative real-time polymerase chain reaction studies show that AmpR binds to the ampC promoter both in the absence and presence of β-lactams. In addition, AmpR directly binds the lasR promoter, encoding the QS master regulator. Comparison of the AmpR-binding sequences from the transcriptome and ChIP-Seq analyses identified an AT-rich consensus-binding motif. This study further attests to the role of AmpR in regulating virulence and physiological processes in P. aeruginosa.
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Affiliation(s)
- Deepak Balasubramanian
- Department of Biological Sciences, College of Arts and Science, Florida International University, Miami, FL 33199, USA, Department of Molecular Microbiology and Infectious Diseases, Herbert Wertheim College of Medicine, Florida International University, Miami, FL 33199, USA, BioRG, School of Computing and Information Science, College of Engineering and Computing, Florida International University, Miami, FL 33199, USA, Division of Infectious Diseases, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA and Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA 02115, USA
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34
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Loza-Correa M, Sahr T, Rolando M, Daniels C, Petit P, Skarina T, Gomez Valero L, Dervins-Ravault D, Honoré N, Savchenko A, Buchrieser C. The Legionella pneumophila kai operon is implicated in stress response and confers fitness in competitive environments. Environ Microbiol 2013; 16:359-81. [PMID: 23957615 DOI: 10.1111/1462-2920.12223] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2013] [Revised: 07/16/2013] [Accepted: 07/19/2013] [Indexed: 01/22/2023]
Abstract
Legionella pneumophila uses aquatic protozoa as replication niche and protection from harsh environments. Although L. pneumophila is not known to have a circadian clock, it encodes homologues of the KaiBC proteins of Cyanobacteria that regulate circadian gene expression. We show that L. pneumophila kaiB, kaiC and the downstream gene lpp1114, are transcribed as a unit under the control of the stress sigma factor RpoS. KaiC and KaiB of L. pneumophila do not interact as evidenced by yeast and bacterial two-hybrid analyses. Fusion of the C-terminal residues of cyanobacterial KaiB to Legionella KaiB restores their interaction. In contrast, KaiC of L. pneumophila conserved autophosphorylation activity, but KaiB does not trigger the dephosphorylation of KaiC like in Cyanobacteria. The crystal structure of L. pneumophila KaiB suggests that it is an oxidoreductase-like protein with a typical thioredoxin fold. Indeed, mutant analyses revealed that the kai operon-encoded proteins increase fitness of L. pneumophila in competitive environments, and confer higher resistance to oxidative and sodium stress. The phylogenetic analysis indicates that L. pneumophila KaiBC resemble Synechosystis KaiC2B2 and not circadian KaiB1C1. Thus, the L. pneumophila Kai proteins do not encode a circadian clock, but enhance stress resistance and adaption to changes in the environments.
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Affiliation(s)
- Maria Loza-Correa
- Institut Pasteur, Biologie des Bactéries Intracellulaires, Paris, France; CNRS UMR 3525, Paris, France
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35
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Park SH, Butcher BG, Anderson Z, Pellegrini N, Bao Z, D’Amico K, Filiatrault MJ. Analysis of the small RNA P16/RgsA in the plant pathogen Pseudomonas syringae pv. tomato strain DC3000. MICROBIOLOGY-SGM 2012; 159:296-306. [PMID: 23258266 PMCID: PMC3709562 DOI: 10.1099/mic.0.063826-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Bacteria contain small non-coding RNAs (ncRNAs) that are responsible for altering transcription, translation or mRNA stability. ncRNAs are important because they regulate virulence factors and susceptibility to various stresses. Here, the regulation of a recently described ncRNA of Pseudomonas syringae pv. tomato DC3000, P16, was investigated. We determined that RpoS regulates the expression of P16. We found that deletion of P16 results in increased sensitivity to hydrogen peroxide compared to the wild-type strain, suggesting that P16 plays a role in the bacteria’s susceptibility to oxidative stress. Additionally the P16 mutant displayed enhanced resistance to heat stress. Our findings provide new information on the regulation and role of this ncRNA in P. syringae.
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Affiliation(s)
- So Hae Park
- Department of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, NY 14853, USA
| | - Bronwyn G. Butcher
- Department of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, NY 14853, USA
| | - Zoe Anderson
- Department of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, NY 14853, USA
| | - Nola Pellegrini
- Plant–Microbe Interactions Research Unit, Robert W. Holley Center for Agriculture and Health, Agricultural Research Service, United States Department of Agriculture, Ithaca, NY 14853, USA
| | - Zhongmeng Bao
- Department of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, NY 14853, USA
| | - Katherine D’Amico
- Department of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, NY 14853, USA
- Plant–Microbe Interactions Research Unit, Robert W. Holley Center for Agriculture and Health, Agricultural Research Service, United States Department of Agriculture, Ithaca, NY 14853, USA
| | - Melanie J. Filiatrault
- Department of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, NY 14853, USA
- Plant–Microbe Interactions Research Unit, Robert W. Holley Center for Agriculture and Health, Agricultural Research Service, United States Department of Agriculture, Ithaca, NY 14853, USA
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Ferrara S, Brugnoli M, De Bonis A, Righetti F, Delvillani F, Dehò G, Horner D, Briani F, Bertoni G. Comparative profiling of Pseudomonas aeruginosa strains reveals differential expression of novel unique and conserved small RNAs. PLoS One 2012; 7:e36553. [PMID: 22590564 PMCID: PMC3349714 DOI: 10.1371/journal.pone.0036553] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2012] [Accepted: 04/04/2012] [Indexed: 12/02/2022] Open
Abstract
Pseudomonas aeruginosa is a highly adaptable bacterium that thrives in a broad range of ecological niches and can infect multiple hosts as diverse as plants, nematodes and mammals. In humans, it is an important opportunistic pathogen. This wide adaptability correlates with its broad genetic diversity. In this study, we used a deep-sequencing approach to explore the complement of small RNAs (sRNAs) in P. aeruginosa as the number of such regulatory molecules previously identified in this organism is relatively low, considering its genome size, phenotypic diversity and adaptability. We have performed a comparative analysis of PAO1 and PA14 strains which share the same host range but differ in virulence, PA14 being considerably more virulent in several model organisms. Altogether, we have identified more than 150 novel candidate sRNAs and validated a third of them by Northern blotting. Interestingly, a number of these novel sRNAs are strain-specific or showed strain-specific expression, strongly suggesting that they could be involved in determining specific phenotypic traits.
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Affiliation(s)
- Silvia Ferrara
- Dipartimento di Scienze Biomolecolari e Biotecnologie, Università degli Studi di Milano, Milan, Italy
| | - Margherita Brugnoli
- Dipartimento di Scienze Biomolecolari e Biotecnologie, Università degli Studi di Milano, Milan, Italy
| | - Angela De Bonis
- Dipartimento di Scienze Biomolecolari e Biotecnologie, Università degli Studi di Milano, Milan, Italy
| | - Francesco Righetti
- Dipartimento di Scienze Biomolecolari e Biotecnologie, Università degli Studi di Milano, Milan, Italy
| | - Francesco Delvillani
- Dipartimento di Scienze Biomolecolari e Biotecnologie, Università degli Studi di Milano, Milan, Italy
| | - Gianni Dehò
- Dipartimento di Scienze Biomolecolari e Biotecnologie, Università degli Studi di Milano, Milan, Italy
| | - David Horner
- Dipartimento di Scienze Biomolecolari e Biotecnologie, Università degli Studi di Milano, Milan, Italy
| | - Federica Briani
- Dipartimento di Scienze Biomolecolari e Biotecnologie, Università degli Studi di Milano, Milan, Italy
- * E-mail: (GB); (FB)
| | - Giovanni Bertoni
- Dipartimento di Scienze Biomolecolari e Biotecnologie, Università degli Studi di Milano, Milan, Italy
- * E-mail: (GB); (FB)
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Gómez-Lozano M, Marvig RL, Molin S, Long KS. Genome-wide identification of novel small RNAs in Pseudomonas aeruginosa. Environ Microbiol 2012; 14:2006-16. [PMID: 22533370 DOI: 10.1111/j.1462-2920.2012.02759.x] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Bacterial small regulatory RNAs (sRNAs) function in post-transcriptional control of gene expression and control a variety of processes including metabolic reactions, stress responses and pathogenesis in response to environmental signals. A variety of approaches have been used previously to identify 44 sRNAs in the opportunistic human pathogen Pseudomonas aeruginosa. In this work, RNA sequencing (RNA-seq) is used to identify novel transcripts in P.aeruginosa involving a combination of three different sequencing libraries. Almost all known sRNAs and over 500 novel intergenic sRNAs are identified with this approach. Although the use of three libraries increased the number of novel transcripts identified, there were significant differences in the subset of transcripts detected in each library, underscoring the importance of library preparation strategy and relative sRNA abundance for successful sRNA detection. Nearly 90% of the novel sRNAs have no orthologous bacterial sequences outside of P.aeruginosa, supporting a limited degree of sequence conservation and rapid evolution of sRNAs at the species level. We anticipate that the data will be useful for the study of regulatory sRNAs in bacteria and that the approach described here may be applied to identify sRNAs in any bacterium under different growth and stress conditions.
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Affiliation(s)
- María Gómez-Lozano
- Department of Systems Biology, Technical University of Denmark, Lyngby, Denmark
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38
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Sonnleitner E, Romeo A, Bläsi U. Small regulatory RNAs in Pseudomonas aeruginosa. RNA Biol 2012; 9:364-71. [PMID: 22336763 DOI: 10.4161/rna.19231] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The opportunistic human pathogen Pseudomonas aeruginosa is frequently associated with nosocomial infections, and can be life threatening in immunosuppressed, cancer and cystic fibrosis patients. Virulence in P. aeruginosa is combinatorial, and results from the activation of several genetic programs that regulate motility, attachment to the host epithelium as well as the synthesis of exotoxins. The pathogen has a high survival capacity in the host owing to its metabolic versatility, nutrient scavenging and resistance against both, antibiotics and immune defenses. Adaptive responses to various environmental stresses and stimuli are often regulated by small regulatory RNAs (sRNA). In this review, we summarize the current knowledge on the regulation and function of P. aeruginosa sRNAs that titrate regulatory proteins, base-pair with target mRNAs, and which are derived from CRISPR elements.
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Affiliation(s)
- Elisabeth Sonnleitner
- Department of Microbiology, Immunobiology and Genetics, Max F. Perutz Laboratories, University of Vienna, Vienna, Austria
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The Pseudomonas aeruginosa transcriptome in planktonic cultures and static biofilms using RNA sequencing. PLoS One 2012; 7:e31092. [PMID: 22319605 PMCID: PMC3272035 DOI: 10.1371/journal.pone.0031092] [Citation(s) in RCA: 175] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2011] [Accepted: 01/02/2012] [Indexed: 11/25/2022] Open
Abstract
In this study, we evaluated how gene expression differs in mature Pseudomonas aeruginosa biofilms as opposed to planktonic cells by the use of RNA sequencing technology that gives rise to both quantitative and qualitative information on the transcriptome. Although a large proportion of genes were consistently regulated in both the stationary phase and biofilm cultures as opposed to the late exponential growth phase cultures, the global biofilm gene expression pattern was clearly distinct indicating that biofilms are not just surface attached cells in stationary phase. A large amount of the genes found to be biofilm specific were involved in adaptation to microaerophilic growth conditions, repression of type three secretion and production of extracellular matrix components. Additionally, we found many small RNAs to be differentially regulated most of them similarly in stationary phase cultures and biofilms. A qualitative analysis of the RNA-seq data revealed more than 3000 putative transcriptional start sites (TSS). By the use of rapid amplification of cDNA ends (5′-RACE) we confirmed the presence of three different TSS associated with the pqsABCDE operon, two in the promoter of pqsA and one upstream of the second gene, pqsB. Taken together, this study reports the first transcriptome study on P. aeruginosa that employs RNA sequencing technology and provides insights into the quantitative and qualitative transcriptome including the expression of small RNAs in P. aeruginosa biofilms.
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Phenotypic switching in Pseudomonas brassicacearum involves GacS- and GacA-dependent Rsm small RNAs. Appl Environ Microbiol 2012; 78:1658-65. [PMID: 22247157 DOI: 10.1128/aem.06769-11] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
The plant-beneficial bacterium Pseudomonas brassicacearum forms phenotypic variants in vitro as well as in planta during root colonization under natural conditions. Transcriptome analysis of typical phenotypic variants using microarrays containing coding as well as noncoding DNA fragments showed differential expression of several genes relevant to secondary metabolism and of the small RNA (sRNA) genes rsmX, rsmY, and rsmZ. Naturally occurring mutations in the gacS-gacA system accounted for phenotypic switching, which was characterized by downregulation of antifungal secondary metabolites (2,4-diacetylphloroglucinol and cyanide), indoleacetate, exoenzymes (lipase and protease), and three different N-acyl-homoserine lactone molecules. Moreover, in addition to abrogating these biocontrol traits, gacS and gacA mutations resulted in reduced expression of the type VI secretion machinery, alginate biosynthesis, and biofilm formation. In a gacA mutant, the expression of rsmX was completely abolished, unlike that of rsmY and rsmZ. Overexpression of any of the three sRNAs in the gacA mutant overruled the pleiotropic changes and restored the wild-type phenotypes, suggesting functional redundancy of these sRNAs. In conclusion, our data show that phenotypic switching in P. brassicacearum results from mutations in the gacS-gacA system.
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Small RNAs as regulators of primary and secondary metabolism in Pseudomonas species. Appl Microbiol Biotechnol 2011; 91:63-79. [PMID: 21607656 DOI: 10.1007/s00253-011-3332-1] [Citation(s) in RCA: 102] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2011] [Revised: 04/11/2011] [Accepted: 04/11/2011] [Indexed: 10/18/2022]
Abstract
Small RNAs (sRNAs) exert important functions in pseudomonads. Classical sRNAs comprise the 4.5S, 6S, 10Sa and 10Sb RNAs, which are known in enteric bacteria as part of the signal recognition particle, a regulatory component of RNA polymerase, transfer-messenger RNA (tmRNA) and the RNA component of RNase P, respectively. Their homologues in pseudomonads are presumed to have analogous functions. Other sRNAs of pseudomonads generally have little or no sequence similarity with sRNAs of enteric bacteria. Numerous sRNAs repress or activate the translation of target mRNAs by a base-pairing mechanism. Examples of this group in Pseudomonas aeruginosa are the iron-repressible PrrF1 and PrrF2 sRNAs, which repress the translation of genes encoding iron-containing proteins, and PhrS, an anaerobically inducible sRNA, which activates the expression of PqsR, a regulator of the Pseudomonas quinolone signal. Other sRNAs sequester RNA-binding proteins that act as translational repressors. Examples of this group in P. aeruginosa include RsmY and RsmZ, which are central regulatory elements in the GacS/GacA signal transduction pathway, and CrcZ, which is a key regulator in the CbrA/CbrB signal transduction pathway. These pathways largely control the extracellular activities (including virulence traits) and the selection of the energetically most favourable carbon sources, respectively, in pseudomonads.
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Azithromycin inhibits expression of the GacA-dependent small RNAs RsmY and RsmZ in Pseudomonas aeruginosa. Antimicrob Agents Chemother 2011; 55:3399-405. [PMID: 21537014 DOI: 10.1128/aac.01801-10] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Azithromycin at clinically relevant doses does not inhibit planktonic growth of the opportunistic pathogen Pseudomonas aeruginosa but causes markedly reduced formation of biofilms and quorum-sensing-regulated extracellular virulence factors. In the Gac/Rsm signal transduction pathway, which acts upstream of the quorum-sensing machinery in P. aeruginosa, the GacA-dependent untranslated small RNAs RsmY and RsmZ are key regulatory elements. As azithromycin treatment and mutational inactivation of gacA have strikingly similar phenotypic consequences, the effect of azithromycin on rsmY and rsmZ expression was investigated. In planktonically growing cells, the antibiotic strongly inhibited the expression of both small RNA genes but did not affect the expression of the housekeeping gene proC. The azithromycin treatment resulted in reduced expression of gacA and rsmA, which are known positive regulators of rsmY and rsmZ, and of the PA0588-PA0584 gene cluster, which was discovered as a novel positive regulatory element involved in rsmY and rsmZ expression. Deletion of this cluster resulted in diminished ability of P. aeruginosa to produce pyocyanin and to swarm. The results of this study indicate that azithromycin inhibits rsmY and rsmZ transcription indirectly by lowering the expression of positive regulators of these small RNA genes.
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Abstract
While many of the initial studies of regulatory small RNA (sRNA) function focused on Escherichia coli and Salmonella, there is expanding characterization of sRNAs in other bacteria. These studies are revealing unique permutations of the themes found in E. coli and Salmonella. This point is nicely illustrated by the Pseudomonas aeruginosa Hfq-binding RNA, PhrS, which activates the synthesis of the key quorum sensing transcription regulator PqsR as described by Sonnleitner et al. in the current issue of Molecular Microbiology. The PhrS RNA combines features of several previously characterized sRNAs; its expression is induced by low oxygen, it encodes a small protein, and it modulates the expression of a quorum sensing regulator by preventing the formation of an inhibitory secondary structure. However, in contrast to other base pairing sRNAs that activate translation, PhrS does not act directly on pqsR but rather increases the translation of a small upstream open reading frame (uof) whose translation is coupled to pqsR.
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Affiliation(s)
- Cynthia Mira Sharma
- Research Centre for Infectious Diseases (ZINF), University of Würzburg, Würzburg, Germany.
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Sonnleitner E, Gonzalez N, Sorger-Domenigg T, Heeb S, Richter AS, Backofen R, Williams P, Hüttenhofer A, Haas D, Bläsi U. The small RNA PhrS stimulates synthesis of the Pseudomonas aeruginosa quinolone signal. Mol Microbiol 2011; 80:868-85. [PMID: 21375594 DOI: 10.1111/j.1365-2958.2011.07620.x] [Citation(s) in RCA: 135] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Quorum sensing, a cell-to-cell communication system based on small signal molecules, is employed by the human pathogen Pseudomonas aeruginosa to regulate virulence and biofilm development. Moreover, regulation by small trans-encoded RNAs has become a focal issue in studies of virulence gene expression of bacterial pathogens. In this study, we have identified the small RNA PhrS as an activator of PqsR synthesis, one of the key quorum-sensing regulators in P. aeruginosa. Genetic studies revealed a novel mode of regulation by a sRNA, whereby PhrS uses a base-pairing mechanism to activate a short upstream open reading frame to which the pqsR gene is translationally coupled. Expression of phrS requires the oxygen-responsive regulator ANR. Thus, PhrS is the first bacterial sRNA that provides a regulatory link between oxygen availability and quorum sensing, which may impact on oxygen-limited growth in P. aeruginosa biofilms.
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Affiliation(s)
- Elisabeth Sonnleitner
- Max F. Perutz Laboratories, Department of Microbiology, Immunobiology and Genetics, University of Vienna, Dr Bohrgasse 9, 1030 Vienna, Austria.
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Frank S, Klockgether J, Hagendorf P, Geffers R, Schöck U, Pohl T, Davenport CF, Tümmler B. Pseudomonas putida KT2440 genome update by cDNA sequencing and microarray transcriptomics. Environ Microbiol 2011; 13:1309-26. [PMID: 21355971 DOI: 10.1111/j.1462-2920.2011.02430.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Pseudomonas putida KT2440 is a completely sequenced biosafety strain that has retained its capability to survive and function in the environment. The global mRNA expression profiles of the KT2440 strain grown at 10°C and 30°C were determined by deep cDNA sequencing to refine the genome annotation. Transcriptome sequencing identified 36 yet unknown small non-coding RNAs, 143 novel ORFs in 106 intergenic regions, 42 unclassified genes and eight highly expressed leaderless mRNA transcripts. The genome coordinates of eight genes and the organization of 57 operons were corrected. No overrepresented sequence motifs were detected in the 5'-untranslated regions. The 50 most highly expressed genes made up 60% of the total mRNA pool. Comparison of cDNA sequencing, Affymetrix and Progenika microarray data from the same mRNA preparation revealed a higher sensitivity and specificity of cDNA sequencing, a relatively poor correlation between the normalized cDNA reads and microarray signal intensities, and a systematic signal-dependent bias of microarrays in the detection of differentially regulated genes. The study demonstrates the power of next-generation cDNA sequencing for the quantitation of mRNA transcripts and the refinement of bacterial genome annotation.
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Affiliation(s)
- Sarah Frank
- Klinische Forschergruppe, Medizinische Hochschule Hannover, Carl-Neuberg-Strasse 1, Hannover, Germany
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A cis-encoded antisense small RNA regulated by the HP0165-HP0166 two-component system controls expression of ureB in Helicobacter pylori. J Bacteriol 2010; 193:40-51. [PMID: 20971914 DOI: 10.1128/jb.00800-10] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Expression of urease is essential for gastric colonization by Helicobacter pylori. The increased level of urease in gastric acidity is due, in part, to acid activation of the two-component system (TCS) consisting of the membrane sensor HP0165 and its response regulator, HP0166, which regulates transcription of the seven genes of the urease gene cluster. We now find that there are two major ureAB transcripts: a 2.7-kb full-length ureAB transcript and a 1.4-kb truncated transcript lacking 3' ureB. Acidic pH (pH 4.5) results in a significant increase in transcription of ureAB, while neutral pH (pH 7.4) increases the truncated 1.4-kb transcript. Northern blot analysis with sense RNA and strand-specific oligonucleotide probes followed by 5' rapid amplification of cDNA ends detects an antisense small RNA (sRNA) encoded by the 5' ureB noncoding strand consisting of ∼290 nucleotides (5'ureB-sRNA). Deletion of HP0165 elevates the level of the truncated 1.4-kb transcript along with that of the 5'ureB-sRNA at both pH 7.4 and pH 4.5. Overexpression of 5'ureB-sRNA increases the 1.4-kb transcript, decreases the 2.7-kb transcript, and decreases urease activity. Electrophoretic mobility shift assay shows that unphosphorylated HP0166 binds specifically to the 5'ureB-sRNA promoter. The ability of the HP0165-HP0166 TCS to both increase and decrease ureB expression at low and high pHs, respectively, facilitates gastric habitation and colonization over the wide range of intragastric pHs experienced by the organism.
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Chinni SV, Raabe CA, Zakaria R, Randau G, Hoe CH, Zemann A, Brosius J, Tang TH, Rozhdestvensky TS. Experimental identification and characterization of 97 novel npcRNA candidates in Salmonella enterica serovar Typhi. Nucleic Acids Res 2010; 38:5893-908. [PMID: 20460466 PMCID: PMC2943607 DOI: 10.1093/nar/gkq281] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
We experimentally identified and characterized 97 novel, non-protein-coding RNA candidates (npcRNAs) from the human pathogen Salmonella enterica serovar Typhi (hereafter referred to as S. typhi). Three were specific to S. typhi, 22 were restricted to Salmonella species and 33 were differentially expressed during S. typhi growth. We also identified Salmonella Pathogenicity Island-derived npcRNAs that might be involved in regulatory mechanisms of virulence, antibiotic resistance and pathogenic specificity of S. typhi. An in-depth characterization of S. typhi StyR-3 npcRNA showed that it specifically interacts with RamR, the transcriptional repressor of the ramA gene, which is involved in the multidrug resistance (MDR) of Salmonella. StyR-3 interfered with RamR–DNA binding activity and thus potentially plays a role in regulating ramA gene expression, resulting in the MDR phenotype. Our study also revealed a large number of cis-encoded antisense npcRNA candidates, supporting previous observations of global sense–antisense regulatory networks in bacteria. Finally, at least six of the npcRNA candidates interacted with the S. typhi Hfq protein, supporting an important role of Hfq in npcRNA networks. This study points to novel functional npcRNA candidates potentially involved in various regulatory roles including the pathogenicity of S. typhi.
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Affiliation(s)
- Suresh V Chinni
- Institute of Experimental Pathology (ZMBE), University of Muenster, Von-Esmarch-Str. 56, 48149 Muenster, Germany
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Bordi C, Lamy MC, Ventre I, Termine E, Hachani A, Fillet S, Roche B, Bleves S, Méjean V, Lazdunski A, Filloux A. Regulatory RNAs and the HptB/RetS signalling pathways fine-tune Pseudomonas aeruginosa pathogenesis. Mol Microbiol 2010; 76:1427-43. [PMID: 20398205 PMCID: PMC2904497 DOI: 10.1111/j.1365-2958.2010.07146.x] [Citation(s) in RCA: 116] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Bacterial pathogenesis often depends on regulatory networks, two-component systems and small RNAs (sRNAs). In Pseudomonas aeruginosa, the RetS sensor pathway downregulates expression of two sRNAs, rsmY and rsmZ. Consequently, biofilm and the Type Six Secretion System (T6SS) are repressed, whereas the Type III Secretion System (T3SS) is activated. We show that the HptB signalling pathway controls biofilm and T3SS, and fine-tunes P. aeruginosa pathogenesis. We demonstrate that RetS and HptB intersect at the GacA response regulator, which directly controls sRNAs production. Importantly, RetS controls both sRNAs, whereas HptB exclusively regulates rsmY expression. We reveal that HptB signalling is a complex regulatory cascade. This cascade involves a response regulator, with an output domain belonging to the phosphatase 2C family, and likely an anti-anti-σ factor. This reveals that the initial input in the Gac system comes from several signalling pathways, and the final output is adjusted by a differential control on rsmY and rsmZ. This is exemplified by the RetS-dependent but HptB-independent control on T6SS. We also demonstrate a redundant action of the two sRNAs on T3SS gene expression, while the impact on pel gene expression is additive. These features underpin a novel mechanism in the fine-tuned regulation of gene expression.
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Affiliation(s)
- Christophe Bordi
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires, UPR9027, CNRS-IMM, Université de la Méditerranée, 31 Chemin Joseph Aiguier, 13402 Marseille cedex 20, France
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Comparative genomics reveals 104 candidate structured RNAs from bacteria, archaea, and their metagenomes. Genome Biol 2010; 11:R31. [PMID: 20230605 PMCID: PMC2864571 DOI: 10.1186/gb-2010-11-3-r31] [Citation(s) in RCA: 284] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2009] [Revised: 01/18/2010] [Accepted: 03/15/2010] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Structured noncoding RNAs perform many functions that are essential for protein synthesis, RNA processing, and gene regulation. Structured RNAs can be detected by comparative genomics, in which homologous sequences are identified and inspected for mutations that conserve RNA secondary structure. RESULTS By applying a comparative genomics-based approach to genome and metagenome sequences from bacteria and archaea, we identified 104 candidate structured RNAs and inferred putative functions for many of these. Twelve candidate metabolite-binding RNAs were identified, three of which were validated, including one reported herein that binds the coenzyme S-adenosylmethionine. Newly identified cis-regulatory RNAs are implicated in photosynthesis or nitrogen regulation in cyanobacteria, purine and one-carbon metabolism, stomach infection by Helicobacter, and many other physiological processes. A candidate riboswitch termed crcB is represented in both bacteria and archaea. Another RNA motif may control gene expression from 3'-untranslated regions of mRNAs, which is unusual for bacteria. Many noncoding RNAs that likely act in trans are also revealed, and several of the noncoding RNA candidates are found mostly or exclusively in metagenome DNA sequences. CONCLUSIONS This work greatly expands the variety of highly structured noncoding RNAs known to exist in bacteria and archaea and provides a starting point for biochemical and genetic studies needed to validate their biologic functions. Given the sustained rate of RNA discovery over several similar projects, we expect that far more structured RNAs remain to be discovered from bacterial and archaeal organisms.
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Hassan KA, Johnson A, Shaffer BT, Ren Q, Kidarsa TA, Elbourne LDH, Hartney S, Duboy R, Goebel NC, Zabriskie TM, Paulsen IT, Loper JE. Inactivation of the GacA response regulator in Pseudomonas fluorescens Pf-5 has far-reaching transcriptomic consequences. Environ Microbiol 2010; 12:899-915. [PMID: 20089046 DOI: 10.1111/j.1462-2920.2009.02134.x] [Citation(s) in RCA: 100] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The GacS/GacA signal transduction system is a central regulator in Pseudomonas spp., including the biological control strain P. fluorescens Pf-5, in which GacS/GacA controls the production of secondary metabolites and exoenzymes that suppress plant pathogens. A whole genome oligonucleotide microarray was developed for Pf-5 and used to assess the global transcriptomic consequences of a gacA mutation in P. fluorescens Pf-5. In cultures at the transition from exponential to stationary growth phase, GacA significantly influenced transcript levels of 635 genes, representing more than 10% of the 6147 annotated genes in the Pf-5 genome. Transcripts of genes involved in the production of hydrogen cyanide, the antibiotic pyoluteorin and the extracellular protease AprA were at a low level in the gacA mutant, whereas those functioning in siderophore production and other aspects of iron homeostasis were significantly higher in the gacA mutant than in wild-type Pf-5. Notable effects of gacA inactivation were also observed in the transcription of genes encoding components of a type VI secretion system and cytochrome c oxidase subunits. Two novel gene clusters expressed under the control of gacA were identified from transcriptome analysis, and we propose global-regulator-based genome mining as an approach to decipher the secondary metabolome of Pseudomonas spp.
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Affiliation(s)
- Karl A Hassan
- Department of Chemistry and Biomolecular Sciences, Macquarie University, NSW, Australia
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