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Michaelis S, Gomez-Valero L, Chen T, Schmid C, Buchrieser C, Hilbi H. Small molecule communication of Legionella: the ins and outs of autoinducer and nitric oxide signaling. Microbiol Mol Biol Rev 2024; 88:e0009723. [PMID: 39162424 PMCID: PMC11426016 DOI: 10.1128/mmbr.00097-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/21/2024] Open
Abstract
SUMMARYLegionella pneumophila is a Gram-negative environmental bacterium, which survives in planktonic form, colonizes biofilms, and infects protozoa. Upon inhalation of Legionella-contaminated aerosols, the opportunistic pathogen replicates within and destroys alveolar macrophages, thereby causing a severe pneumonia termed Legionnaires' disease. Gram-negative bacteria employ low molecular weight organic compounds as well as the inorganic gas nitric oxide (NO) for cell-cell communication. L. pneumophila produces, secretes, and detects the α-hydroxyketone compound Legionella autoinducer-1 (LAI-1, 3-hydroxypentadecane-4-one). LAI-1 is secreted by L. pneumophila in outer membrane vesicles and not only promotes communication among bacteria but also triggers responses from eukaryotic cells. L. pneumophila detects NO through three different receptors, and signaling through the volatile molecule translates into fluctuations of the intracellular second messenger cyclic-di-guanylate monophosphate. The LAI-1 and NO signaling pathways are linked via the pleiotropic transcription factor LvbR. In this review, we summarize current knowledge about inter-bacterial and inter-kingdom signaling through LAI-1 and NO by Legionella species.
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Affiliation(s)
- Sarah Michaelis
- Institute of Medical Microbiology, University of Zürich, Zürich, Switzerland
| | - Laura Gomez-Valero
- Institut Pasteur, Université de Paris, Unité Biologie des Bactéries Intracellulaires, Paris, France
| | - Tong Chen
- Institute of Medical Microbiology, University of Zürich, Zürich, Switzerland
| | - Camille Schmid
- Institute of Medical Microbiology, University of Zürich, Zürich, Switzerland
| | - Carmen Buchrieser
- Institut Pasteur, Université de Paris, Unité Biologie des Bactéries Intracellulaires, Paris, France
| | - Hubert Hilbi
- Institute of Medical Microbiology, University of Zürich, Zürich, Switzerland
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Vaňková Hausnerová V, Shoman M, Kumar D, Schwarz M, Modrák M, Jirát Matějčková J, Mikesková E, Neva S, Herrmannová A, Šiková M, Halada P, Novotná I, Pajer P, Valášek LS, Převorovský M, Krásný L, Hnilicová J. RIP-seq reveals RNAs that interact with RNA polymerase and primary sigma factors in bacteria. Nucleic Acids Res 2024; 52:4604-4626. [PMID: 38348908 PMCID: PMC11077062 DOI: 10.1093/nar/gkae081] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2023] [Revised: 01/24/2024] [Accepted: 01/29/2024] [Indexed: 05/09/2024] Open
Abstract
Bacteria have evolved structured RNAs that can associate with RNA polymerase (RNAP). Two of them have been known so far-6S RNA and Ms1 RNA but it is unclear if any other types of RNAs binding to RNAP exist in bacteria. To identify all RNAs interacting with RNAP and the primary σ factors, we have established and performed native RIP-seq in Bacillus subtilis, Corynebacterium glutamicum, Streptomyces coelicolor, Mycobacterium smegmatis and the pathogenic Mycobacterium tuberculosis. Besides known 6S RNAs in B. subtilis and Ms1 in M. smegmatis, we detected MTS2823, a homologue of Ms1, on RNAP in M. tuberculosis. In C. glutamicum, we discovered novel types of structured RNAs that associate with RNAP. Furthermore, we identified other species-specific RNAs including full-length mRNAs, revealing a previously unknown landscape of RNAs interacting with the bacterial transcription machinery.
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Affiliation(s)
- Viola Vaňková Hausnerová
- Laboratory of Microbial Genetics and Gene Expression, Institute of Microbiology of the Czech Academy of Sciences, Prague142 20, Czech Republic
- Laboratory of Regulatory RNAs, Faculty of Science, Charles University, Prague128 44, Czech Republic
| | - Mahmoud Shoman
- Laboratory of Microbial Genetics and Gene Expression, Institute of Microbiology of the Czech Academy of Sciences, Prague142 20, Czech Republic
- Laboratory of Regulatory RNAs, Faculty of Science, Charles University, Prague128 44, Czech Republic
| | - Dilip Kumar
- Laboratory of Microbial Genetics and Gene Expression, Institute of Microbiology of the Czech Academy of Sciences, Prague142 20, Czech Republic
| | - Marek Schwarz
- Laboratory of Bioinformatics, Institute of Microbiology of the Czech Academy of Sciences, Prague142 20, Czech Republic
| | - Martin Modrák
- Laboratory of Bioinformatics, Institute of Microbiology of the Czech Academy of Sciences, Prague142 20, Czech Republic
- Department of Bioinformatics, Second Faculty of Medicine, Charles University, Prague150 06, Czech Republic
| | - Jitka Jirát Matějčková
- Laboratory of Microbial Genetics and Gene Expression, Institute of Microbiology of the Czech Academy of Sciences, Prague142 20, Czech Republic
- Laboratory of Regulatory RNAs, Faculty of Science, Charles University, Prague128 44, Czech Republic
| | - Eliška Mikesková
- Laboratory of Microbial Genetics and Gene Expression, Institute of Microbiology of the Czech Academy of Sciences, Prague142 20, Czech Republic
- Laboratory of Regulatory RNAs, Faculty of Science, Charles University, Prague128 44, Czech Republic
| | - Silvia Neva
- Laboratory of Microbial Genetics and Gene Expression, Institute of Microbiology of the Czech Academy of Sciences, Prague142 20, Czech Republic
- Laboratory of Regulatory RNAs, Faculty of Science, Charles University, Prague128 44, Czech Republic
| | - Anna Herrmannová
- Laboratory of Regulation of Gene Expression, Institute of Microbiology of the Czech Academy of Sciences, Prague142 20, Czech Republic
| | - Michaela Šiková
- Laboratory of Microbial Genetics and Gene Expression, Institute of Microbiology of the Czech Academy of Sciences, Prague142 20, Czech Republic
| | - Petr Halada
- Laboratory of Structural Biology and Cell Signaling, Institute of Microbiology of the Czech Academy of Sciences, Vestec252 50, Czech Republic
| | - Iva Novotná
- Military Health Institute, Military Medical Agency, Prague169 02, Czech Republic
| | - Petr Pajer
- Military Health Institute, Military Medical Agency, Prague169 02, Czech Republic
| | - Leoš Shivaya Valášek
- Laboratory of Regulation of Gene Expression, Institute of Microbiology of the Czech Academy of Sciences, Prague142 20, Czech Republic
| | - Martin Převorovský
- Department of Cell Biology, Faculty of Science, Charles University, Prague128 00, Czech Republic
| | - Libor Krásný
- Laboratory of Microbial Genetics and Gene Expression, Institute of Microbiology of the Czech Academy of Sciences, Prague142 20, Czech Republic
| | - Jarmila Hnilicová
- Laboratory of Microbial Genetics and Gene Expression, Institute of Microbiology of the Czech Academy of Sciences, Prague142 20, Czech Republic
- Laboratory of Regulatory RNAs, Faculty of Science, Charles University, Prague128 44, Czech Republic
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Majumder R, Ghosh S, Das A, Singh MK, Samanta S, Saha A, Saha RP. Prokaryotic ncRNAs: Master regulators of gene expression. CURRENT RESEARCH IN PHARMACOLOGY AND DRUG DISCOVERY 2022; 3:100136. [PMID: 36568271 PMCID: PMC9780080 DOI: 10.1016/j.crphar.2022.100136] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 09/11/2022] [Accepted: 10/14/2022] [Indexed: 12/14/2022] Open
Abstract
ncRNA plays a very pivotal role in various biological activities ranging from gene regulation to controlling important developmental networks. It is imperative to note that this small molecule is not only present in all three domains of cellular life, but is an important modulator of gene regulation too in all these domains. In this review, we discussed various aspects of ncRNA biology, especially their role in bacteria. The last two decades of scientific research have proved that this molecule plays an important role in the modulation of various regulatory pathways in bacteria including the adaptive immune system and gene regulation. It is also very surprising to note that this small molecule is also employed in various processes related to the pathogenicity of virulent microorganisms.
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Affiliation(s)
- Rajib Majumder
- Department of Biotechnology, School of Life Science & Biotechnology, Adamas University, Kolkata, 700126, India
| | - Sanmitra Ghosh
- Department of Biological Sciences, School of Life Science & Biotechnology, Adamas University, Kolkata, 700126, India
| | - Arpita Das
- Department of Biotechnology, School of Life Science & Biotechnology, Adamas University, Kolkata, 700126, India
| | - Manoj Kumar Singh
- Department of Biotechnology, School of Life Science & Biotechnology, Adamas University, Kolkata, 700126, India
| | - Saikat Samanta
- Department of Biotechnology, School of Life Science & Biotechnology, Adamas University, Kolkata, 700126, India
| | - Abinit Saha
- Department of Biotechnology, School of Life Science & Biotechnology, Adamas University, Kolkata, 700126, India,Corresponding authors.
| | - Rudra P. Saha
- Department of Biotechnology, School of Life Science & Biotechnology, Adamas University, Kolkata, 700126, India,Corresponding authors.
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Vaňková Hausnerová V, Marvalová O, Šiková M, Shoman M, Havelková J, Kambová M, Janoušková M, Kumar D, Halada P, Schwarz M, Krásný L, Hnilicová J, Pánek J. Ms1 RNA Interacts With the RNA Polymerase Core in Streptomyces coelicolor and Was Identified in Majority of Actinobacteria Using a Linguistic Gene Synteny Search. Front Microbiol 2022; 13:848536. [PMID: 35633709 PMCID: PMC9130861 DOI: 10.3389/fmicb.2022.848536] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Accepted: 02/22/2022] [Indexed: 11/15/2022] Open
Abstract
Bacteria employ small non-coding RNAs (sRNAs) to regulate gene expression. Ms1 is an sRNA that binds to the RNA polymerase (RNAP) core and affects the intracellular level of this essential enzyme. Ms1 is structurally related to 6S RNA that binds to a different form of RNAP, the holoenzyme bearing the primary sigma factor. 6S RNAs are widespread in the bacterial kingdom except for the industrially and medicinally important Actinobacteria. While Ms1 RNA was identified in Mycobacterium, it is not clear whether Ms1 RNA is present also in other Actinobacteria species. Here, using a computational search based on secondary structure similarities combined with a linguistic gene synteny approach, we identified Ms1 RNA in Streptomyces. In S. coelicolor, Ms1 RNA overlaps with the previously annotated scr3559 sRNA with an unknown function. We experimentally confirmed that Ms1 RNA/scr3559 associates with the RNAP core without the primary sigma factor HrdB in vivo. Subsequently, we applied the computational approach to other Actinobacteria and identified Ms1 RNA candidates in 824 Actinobacteria species, revealing Ms1 RNA as a widespread class of RNAP binding sRNAs, and demonstrating the ability of our multifactorial computational approach to identify weakly conserved sRNAs in evolutionarily distant genomes.
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Affiliation(s)
- Viola Vaňková Hausnerová
- Laboratory of Microbial Genetics and Gene Expression, Institute of Microbiology of the Czech Academy of Sciences, Prague, Czechia
| | - Olga Marvalová
- Laboratory of Microbial Genetics and Gene Expression, Institute of Microbiology of the Czech Academy of Sciences, Prague, Czechia
| | - Michaela Šiková
- Laboratory of Microbial Genetics and Gene Expression, Institute of Microbiology of the Czech Academy of Sciences, Prague, Czechia
| | - Mahmoud Shoman
- Laboratory of Microbial Genetics and Gene Expression, Institute of Microbiology of the Czech Academy of Sciences, Prague, Czechia
| | - Jarmila Havelková
- Laboratory of Microbial Genetics and Gene Expression, Institute of Microbiology of the Czech Academy of Sciences, Prague, Czechia
| | - Milada Kambová
- Laboratory of Microbial Genetics and Gene Expression, Institute of Microbiology of the Czech Academy of Sciences, Prague, Czechia
| | - Martina Janoušková
- Laboratory of Microbial Genetics and Gene Expression, Institute of Microbiology of the Czech Academy of Sciences, Prague, Czechia
| | - Dilip Kumar
- Laboratory of Microbial Genetics and Gene Expression, Institute of Microbiology of the Czech Academy of Sciences, Prague, Czechia
| | - Petr Halada
- Laboratory of Structural Biology and Cell Signaling, Institute of Microbiology of the Czech Academy of Sciences, Vestec, Czechia
| | - Marek Schwarz
- Laboratory of Bioinformatics, Institute of Microbiology of the Czech Academy of Sciences, Prague, Czechia
| | - Libor Krásný
- Laboratory of Microbial Genetics and Gene Expression, Institute of Microbiology of the Czech Academy of Sciences, Prague, Czechia
| | - Jarmila Hnilicová
- Laboratory of Microbial Genetics and Gene Expression, Institute of Microbiology of the Czech Academy of Sciences, Prague, Czechia
| | - Josef Pánek
- Laboratory of Bioinformatics, Institute of Microbiology of the Czech Academy of Sciences, Prague, Czechia
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Involvement of E. coli 6S RNA in Oxidative Stress Response. Int J Mol Sci 2022; 23:ijms23073653. [PMID: 35409013 PMCID: PMC8998176 DOI: 10.3390/ijms23073653] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 03/15/2022] [Accepted: 03/16/2022] [Indexed: 01/22/2023] Open
Abstract
6S RNA, a small non-coding RNA present in almost all bacteria, inhibits transcription via direct binding to RNA polymerase holoenzymes. The mechanism of 6S RNA action was investigated to a large extent in E. coli, however, lack of 6S RNA (ΔssrS) was demonstrated to be unfavorable but not essential for cell survival under various growth conditions. In the present study, we revealed, for the first time, a lethal phenotype of the ΔssrS strain in the presence of high concentrations of H2O2. This phenotype was rescued by complementation of the ssrS gene on a plasmid. We performed comparative qRT-PCR analyses on an enlarged set of mRNAs of genes associated with the oxidative stress response, allowing us to identify four genes known to be involved in this pathway (soxS, ahpC, sodA and tpx) that had decreased mRNA levels in the ΔssrS strain. Finally, we performed comparative proteomic analyses of the wild-type and ΔssrS strains, confirming that ΔssrS bacteria have reduced levels of the proteins AhpC and Tpx involved in H2O2 reduction. Our findings substantiate the crucial role of the riboregulator 6S RNA for bacterial coping with extreme stresses.
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The Tail-Specific Protease Is Important for Legionella pneumophila To Survive Thermal Stress in Water and inside Amoebae. Appl Environ Microbiol 2021; 87:AEM.02975-20. [PMID: 33608288 DOI: 10.1128/aem.02975-20] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Accepted: 02/09/2021] [Indexed: 12/26/2022] Open
Abstract
Legionella pneumophila (Lp) is an inhabitant of natural and human-made water systems, where it replicates within amoebae and ciliates and survives within biofilms. When Lp-contaminated aerosols are breathed in, Lp can enter the lungs and may infect human alveolar macrophages, causing severe pneumonia known as Legionnaires' disease. Lp is often found in hot water distribution systems (HWDS), which are linked to nosocomial outbreaks. Heat treatment is used to disinfect HWDS and reduce the concentration of Lp However, Lp is often able to recolonize these water systems, indicating an efficient heat shock response. Tail-specific proteases (Tsp) are typically periplasmic proteases implicated in degrading aberrant proteins in the periplasm and important for surviving thermal stress. In Lp Philadelphia-1, Tsp is encoded by the lpg0499 gene. In this paper, we show that Tsp is important for surviving thermal stress in water and for optimal infection of amoeba when a shift in temperature occurs during intracellular growth. We also demonstrate that Tsp is expressed in the postexponential phase but repressed in the exponential phase and that the cis-encoded small regulatory RNA Lpr17 shows the opposite expression, suggesting that it represses translation of tsp In addition, our results show that tsp is regulated by CpxR, a major regulator in Lp, in an Lpr17-independent manner. Deletion of CpxR also reduced the ability of Lp to survive heat shock. In conclusion, our study shows that Tsp is likely an important factor for the survival and growth of Lp in water systems.IMPORTANCE Lp is a major cause of nosocomial and community-acquired pneumonia. Lp is found in water systems, including hot water distribution systems. Heat treatment is a method of disinfection often used to limit the presence of Lp in such systems; however, the benefit is usually short term, as Lp is able to quickly recolonize these systems. Presumably, Lp responds efficiently to thermal stress, but so far, not much is known about the genes involved. In this paper, we show that the Tsp and the two-component system CpxRA are required for resistance to thermal stress when Lp is free in water and when it is inside host cells. Our study identifies critical systems for the survival of Lp in its natural environment under thermal stress.
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Saoud J, Carrier MC, Massé É, Faucher SP. The small regulatory RNA Lpr10 regulates the expression of RpoS in Legionella pneumophila. Mol Microbiol 2020; 115:789-806. [PMID: 33191583 DOI: 10.1111/mmi.14644] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Revised: 11/06/2020] [Accepted: 11/10/2020] [Indexed: 12/25/2022]
Abstract
Legionella pneumophila (Lp) is a waterborne bacterium able to infect human alveolar macrophages, causing Legionnaires' disease. Lp can survive for several months in water, while searching for host cells to grow in, such as ciliates and amoeba. In Lp, the sigma factor RpoS is essential for survival in water. A previous transcriptomic study showed that RpoS positively regulates the small regulatory RNA Lpr10. In the present study, deletion of lpr10 results in an increased survival of Lp in water. Microarray analysis and RT-qPCR revealed that Lpr10 negatively regulates the expression of RpoS in the postexponential phase. Electrophoretic mobility shift assay and in-line probing showed that Lpr10 binds to a region upstream of the previously identified transcription start sites (TSS) of rpoS. A third putative transcription start site was identified by primer extension analysis, upstream of the Lpr10 binding site. In addition, nlpD TSS produces a polycistronic mRNA including the downstream gene rpoS, indicating a fourth TSS for rpoS. Our results suggest that the transcripts from the third and fourth TSS are negatively regulated by the Lpr10 sRNA. Therefore, we propose that Lpr10 is involved in a negative regulatory feedback loop to maintain expression of RpoS to an optimal level.
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Affiliation(s)
- Joseph Saoud
- Department of Natural Resource Sciences, McGill University, Sainte-Anne-de-Bellevue, QC, Canada.,Centre de Recherche en Infectiologie Porcine et Avicole (CRIPA), Université de Montréal, Faculté de Médecine Vétérinaire, Saint-Hyacinthe, QC, Canada
| | - Marie-Claude Carrier
- Department of Biochemistry and Functional Genomics, RNA Group, Université de Sherbrooke, QC, Canada
| | - Éric Massé
- Department of Biochemistry and Functional Genomics, RNA Group, Université de Sherbrooke, QC, Canada
| | - Sébastien P Faucher
- Department of Natural Resource Sciences, McGill University, Sainte-Anne-de-Bellevue, QC, Canada.,Centre de Recherche en Infectiologie Porcine et Avicole (CRIPA), Université de Montréal, Faculté de Médecine Vétérinaire, Saint-Hyacinthe, QC, Canada
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Samuels DS, Lybecker MC, Yang XF, Ouyang Z, Bourret TJ, Boyle WK, Stevenson B, Drecktrah D, Caimano MJ. Gene Regulation and Transcriptomics. Curr Issues Mol Biol 2020; 42:223-266. [PMID: 33300497 DOI: 10.21775/cimb.042.223] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Borrelia (Borreliella) burgdorferi, along with closely related species, is the etiologic agent of Lyme disease. The spirochete subsists in an enzootic cycle that encompasses acquisition from a vertebrate host to a tick vector and transmission from a tick vector to a vertebrate host. To adapt to its environment and persist in each phase of its enzootic cycle, B. burgdorferi wields three systems to regulate the expression of genes: the RpoN-RpoS alternative sigma factor cascade, the Hk1/Rrp1 two-component system and its product c-di-GMP, and the stringent response mediated by RelBbu and DksA. These regulatory systems respond to enzootic phase-specific signals and are controlled or fine- tuned by transcription factors, including BosR and BadR, as well as small RNAs, including DsrABb and Bb6S RNA. In addition, several other DNA-binding and RNA-binding proteins have been identified, although their functions have not all been defined. Global changes in gene expression revealed by high-throughput transcriptomic studies have elucidated various regulons, albeit technical obstacles have mostly limited this experimental approach to cultivated spirochetes. Regardless, we know that the spirochete, which carries a relatively small genome, regulates the expression of a considerable number of genes required for the transitions between the tick vector and the vertebrate host as well as the adaptation to each.
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Affiliation(s)
- D Scott Samuels
- Division of Biological Sciences, University of Montana, Missoula, MT 59812, USA
| | - Meghan C Lybecker
- Department of Biology, University of Colorado, Colorado Springs, CO 80918, USA
| | - X Frank Yang
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Zhiming Ouyang
- Department of Molecular Medicine, University of South Florida, Tampa, FL 33612, USA
| | - Travis J Bourret
- Department of Medical Microbiology and Immunology, Creighton University, Omaha, NE, 68105 USA
| | - William K Boyle
- Department of Medical Microbiology and Immunology, Creighton University, Omaha, NE, 68105 USA
| | - Brian Stevenson
- Department of Microbiology, Immunology and Molecular Genetics, University of Kentucky School of Medicine, Lexington, KY 40536, USA
| | - Dan Drecktrah
- Division of Biological Sciences, University of Montana, Missoula, MT 59812, USA
| | - Melissa J Caimano
- Departments of Medicine, Pediatrics, and Molecular Biology and Biophysics, UConn Health, Farmington, CT, USA
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Similarities and differences between 6S RNAs from Bradyrhizobium japonicum and Sinorhizobium meliloti. J Microbiol 2020; 58:945-956. [PMID: 33125669 DOI: 10.1007/s12275-020-0283-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Revised: 08/03/2020] [Accepted: 08/03/2020] [Indexed: 10/23/2022]
Abstract
6S RNA, a conserved and abundant small non-coding RNA found in most bacteria, regulates gene expression by inhibiting RNA polymerase (RNAP) holoenzyme. 6S RNAs from α-proteobacteria have been studied poorly so far. Here, we present a first in-depth analysis of 6S RNAs from two α-proteobacteria species, Bradyrhizobium japonicum and Sinorhizobium meliloti. Although both belong to the order Rhizobiales and are typical nitrogen-fixing symbionts of legumes, their 6S RNA expression profiles were found to differ: B. japonicum 6S RNA accumulated in the stationary phase, thus being reminiscent of Escherichia coli 6S RNA, whereas S. meliloti 6S RNA level peaked at the transition to the stationary phase, similarly to Rhodobacter sphaeroides 6S RNA. We demonstrated in vitro that both RNAs have hallmarks of 6S RNAs: they bind to the σ70-type RNAP holoenzyme and serve as templates for de novo transcription of so-called product RNAs (pRNAs) ranging in length from ∼13 to 24 nucleotides, with further evidence of the synthesis of even longer pRNAs. Likewise, stably bound pRNAs were found to rearrange the 6S RNA structure to induce its dissociation from RNAP. Compared with B. japonicum 6S RNA, considerable conformational heterogeneity was observed for S. meliloti 6S RNA and its complexes with pRNAs, even though the two 6S RNAs share ∼75% sequence identity. Overall, our findings suggest that the two rhizobial 6S RNAs have diverged with respect to their regulatory impact on gene expression throughout the bacterial life cycle.
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Personnic N, Striednig B, Hilbi H. Quorum sensing controls persistence, resuscitation, and virulence of Legionella subpopulations in biofilms. ISME JOURNAL 2020; 15:196-210. [PMID: 32951019 DOI: 10.1038/s41396-020-00774-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Revised: 08/13/2020] [Accepted: 09/04/2020] [Indexed: 02/07/2023]
Abstract
The water-borne bacterium Legionella pneumophila is the causative agent of Legionnaires' disease. In the environment, the opportunistic pathogen colonizes different niches, including free-living protozoa and biofilms. The physiological state(s) of sessile Legionella in biofilms and their functional consequences are not well understood. Using single-cell techniques and fluorescent growth rate probes as well as promoter reporters, we show here that sessile L. pneumophila exhibits phenotypic heterogeneity and adopts growing and nongrowing ("dormant") states in biofilms and microcolonies. Phenotypic heterogeneity is controlled by the Legionella quorum sensing (Lqs) system, the transcription factor LvbR, and the temperature. The Lqs system and LvbR determine the ratio between growing and nongrowing sessile subpopulations, as well as the frequency of growth resumption ("resuscitation") and microcolony formation of individual bacteria. Nongrowing L. pneumophila cells are metabolically active, express virulence genes and show tolerance toward antibiotics. Therefore, these sessile nongrowers are persisters. Taken together, the Lqs system, LvbR and the temperature control the phenotypic heterogeneity of sessile L. pneumophila, and these factors regulate the formation of a distinct subpopulation of nongrowing, antibiotic tolerant, virulent persisters. Hence, the biofilm niche of L. pneumophila has a profound impact on the ecology and virulence of this opportunistic pathogen.
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Affiliation(s)
- Nicolas Personnic
- Institute of Medical Microbiology, University of Zürich, Gloriastrasse 30, 8006, Zürich, Switzerland.
| | - Bianca Striednig
- Institute of Medical Microbiology, University of Zürich, Gloriastrasse 30, 8006, Zürich, Switzerland
| | - Hubert Hilbi
- Institute of Medical Microbiology, University of Zürich, Gloriastrasse 30, 8006, Zürich, Switzerland.
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11
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Thüring M, Ganapathy S, Schlüter MAC, Lechner M, Hartmann RK. 6S-2 RNA deletion in the undomesticated B. subtilis strain NCIB 3610 causes a biofilm derepression phenotype. RNA Biol 2020; 18:79-92. [PMID: 32862759 DOI: 10.1080/15476286.2020.1795408] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
Abstract
Bacterial 6S RNA regulates transcription via binding to the active site of RNA polymerase holoenzymes. 6S RNA has been identified in the majority of bacteria, in most cases encoded by a single gene. Firmicutes including Bacillus subtilis encode two 6S RNA paralogs, 6S-1 and 6S-2 RNA. Hypothesizing that the regulatory role of 6S RNAs may be particularly important under natural, constantly changing environmental conditions, we constructed 6S RNA deletion mutants of the undomesticated B. subtilis wild-type strain NCIB 3610. We observed a strong phenotype for the ∆6S-2 RNA strain that showed increased biofilm formation on solid media and the ability to form surface-attached biofilms in liquid culture. This phenotype remained undetected in derived laboratory strains (168, PY79) that are defective in biofilm formation. Quantitative RT-PCR data revealed transcriptional upregulation of biofilm marker genes such as tasA, epsA and bslA in the ∆6S-2 RNA strain, particularly during transition from exponential to stationary growth phase. Salt stress, which blocks sporulation at a very early stage, was found to override the derepressed biofilm phenotype of the ∆6S-2 RNA strain. Furthermore, the ∆6S-2 RNA strain showed retarded swarming activity and earlier spore formation. Finally, the ∆6S-1&2 RNA double deletion strain showed a prolonged lag phase of growth under oxidative, high salt and alkaline stress conditions, suggesting that the interplay of both 6S RNAs in B. subtilis optimizes and fine-tunes transcriptomic adaptations, thereby contributing to the fitness of B. subtilis under the unsteady and temporarily harsh conditions encountered in natural habitats.
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Affiliation(s)
- Marietta Thüring
- Institute of Pharmaceutical Chemistry, Philipps-University Marburg , Marburg, Germany
| | - Sweetha Ganapathy
- Institute of Pharmaceutical Chemistry, Philipps-University Marburg , Marburg, Germany
| | - M Amri C Schlüter
- Institute of Pharmaceutical Chemistry, Philipps-University Marburg , Marburg, Germany
| | - Marcus Lechner
- Center for Synthetic Microbiology, Bioinformatics Core Facility , Marburg, Germany
| | - Roland K Hartmann
- Institute of Pharmaceutical Chemistry, Philipps-University Marburg , Marburg, Germany
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Riboregulation in Nitrogen-Fixing Endosymbiotic Bacteria. Microorganisms 2020; 8:microorganisms8030384. [PMID: 32164262 PMCID: PMC7143759 DOI: 10.3390/microorganisms8030384] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Revised: 03/04/2020] [Accepted: 03/05/2020] [Indexed: 01/21/2023] Open
Abstract
Small non-coding RNAs (sRNAs) are ubiquitous components of bacterial adaptive regulatory networks underlying stress responses and chronic intracellular infection of eukaryotic hosts. Thus, sRNA-mediated regulation of gene expression is expected to play a major role in the establishment of mutualistic root nodule endosymbiosis between nitrogen-fixing rhizobia and legume plants. However, knowledge about this level of genetic regulation in this group of plant-interacting bacteria is still rather scarce. Here, we review insights into the rhizobial non-coding transcriptome and sRNA-mediated post-transcriptional regulation of symbiotic relevant traits such as nutrient uptake, cell cycle, quorum sensing, or nodule development. We provide details about the transcriptional control and protein-assisted activity mechanisms of the functionally characterized sRNAs involved in these processes. Finally, we discuss the forthcoming research on riboregulation in legume symbionts.
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Hochstrasser R, Hilbi H. Legionella quorum sensing meets cyclic-di-GMP signaling. Curr Opin Microbiol 2020; 55:9-16. [PMID: 32045871 DOI: 10.1016/j.mib.2020.01.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Accepted: 01/06/2020] [Indexed: 12/25/2022]
Abstract
Bacterial gene regulation occurs through complex networks, wherein linear systems respond to intracellular or extracellular cues and engage on vivid crosstalk. The ubiquitous water-borne bacterium Legionella pneumophila colonizes various distinct environmental niches ranging from biofilms to protozoa, and - as an 'accidental' pathogen - the human lung. Consequently, L. pneumophila gene regulation evolved to integrate a broad spectrum of different endogenous and exogenous signals. Endogenous signals produced and detected by L. pneumophila comprise the quorum sensing autoinducer LAI-1 (3-hydroxypentadecane-4-one) and c-di-GMP. As an exogenous cue, nitric oxide controls the c-di-GMP regulatory network of L. pneumophila. The Legionella quorum sensing (Lqs) system regulates virulence, motility and natural competence of L. pneumophila. The Lqs system is linked to c-di-GMP signaling through the pleiotropic transcription factor LvbR, which also regulates the architecture of L. pneumophila biofilms. In this review, we highlight recent insights into the crosstalk of Legionella quorum sensing and c-di-GMP signaling.
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Affiliation(s)
- Ramon Hochstrasser
- Institute of Medical Microbiology, University of Zürich, Gloriastrasse 30, 8006 Zürich, Switzerland
| | - Hubert Hilbi
- Institute of Medical Microbiology, University of Zürich, Gloriastrasse 30, 8006 Zürich, Switzerland.
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Drecktrah D, Hall LS, Brinkworth AJ, Comstock JR, Wassarman KM, Samuels DS. Characterization of 6S RNA in the Lyme disease spirochete. Mol Microbiol 2020; 113:399-417. [PMID: 31742773 PMCID: PMC7047579 DOI: 10.1111/mmi.14427] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Revised: 11/05/2019] [Accepted: 11/16/2019] [Indexed: 12/31/2022]
Abstract
6S RNA binds to RNA polymerase and regulates gene expression, contributing to bacterial adaptation to environmental stresses. In this study, we examined the role of 6S RNA in murine infectivity and tick persistence of the Lyme disease spirochete Borrelia (Borreliella) burgdorferi. B. burgdorferi 6S RNA (Bb6S RNA) binds to RNA polymerase, is expressed independent of growth phase or nutrient stress in culture, and is processed by RNase Y. We found that rny (bb0504), the gene encoding RNase Y, is essential for B. burgdorferi growth, while ssrS, the gene encoding 6S RNA, is not essential, indicating a broader role for RNase Y activity in the spirochete. Bb6S RNA regulates expression of the ospC and dbpA genes encoding outer surface protein C and decorin binding protein A, respectively, which are lipoproteins important for host infection. The highest levels of Bb6S RNA are found when the spirochete resides in unfed nymphs. ssrS mutants lacking Bb6S RNA were compromised for infectivity by needle inoculation, but injected mice seroconverted, indicating an ability to activate the adaptive immune response. ssrS mutants were successfully acquired by larval ticks and persisted through fed nymphs. Bb6S RNA is one of the first regulatory RNAs identified in B. burgdorferi that controls the expression of lipoproteins involved in host infectivity.
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Affiliation(s)
- Dan Drecktrah
- Division of Biological Sciences, University of Montana, Missoula, MT 59812, USA
| | - Laura S. Hall
- Division of Biological Sciences, University of Montana, Missoula, MT 59812, USA
| | | | | | - Karen M. Wassarman
- Department of Bacteriology, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - D. Scott Samuels
- Division of Biological Sciences, University of Montana, Missoula, MT 59812, USA
- Center for Biomolecular Structure and Dynamics, University of Montana, Missoula, MT 59812, USA
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Abstract
Bacterial regulatory RNAs are key players in adaptation to changing environmental conditions and response to diverse cellular stresses. However, while regulatory RNAs of bacterial pathogens have been intensely studied under defined conditions in vitro, characterization of their role during the infection of eukaryotic host organisms is lagging behind. This review summarizes our current understanding of the contribution of the different classes of regulatory RNAs and RNA-binding proteins to bacterial virulence and illustrates their role in infection by reviewing the mechanisms of some prominent representatives of each class. Emerging technologies are described that bear great potential for global, unbiased studies of virulence-related RNAs in bacterial model and nonmodel pathogens in the future. The review concludes by deducing common principles of RNA-mediated gene expression control of virulence programs in different pathogens, and by defining important open questions for upcoming research in the field.
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Abstract
Small regulatory RNAs are now recognized as key regulators of gene expression in bacteria. They accumulate under specific conditions, most often because their synthesis is directly controlled by transcriptional regulators, including but not limited to alternative sigma factors and response regulators of two-component systems. In turn, small RNAs regulate, mostly at the posttranscriptional level, expression of multiple genes, among which are genes encoding transcriptional regulators. Small RNAs are thus embedded in mixed regulatory circuits combining transcriptional and posttranscriptional controls, and whose properties are discussed here.
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Wassarman KM. 6S RNA, a Global Regulator of Transcription. Microbiol Spectr 2018; 6:10.1128/microbiolspec.RWR-0019-2018. [PMID: 29916345 PMCID: PMC6013841 DOI: 10.1128/microbiolspec.rwr-0019-2018] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Indexed: 01/06/2023] Open
Abstract
6S RNA is a small RNA regulator of RNA polymerase (RNAP) that is present broadly throughout the bacterial kingdom. Initial functional studies in Escherichia coli revealed that 6S RNA forms a complex with RNAP resulting in regulation of transcription, and cells lacking 6S RNA have altered survival phenotypes. The last decade has focused on deepening the understanding of several aspects of 6S RNA activity, including (i) addressing questions of how broadly conserved 6S RNAs are in diverse organisms through continued identification and initial characterization of divergent 6S RNAs; (ii) the nature of the 6S RNA-RNAP interaction through examination of variant proteins and mutant RNAs, cross-linking approaches, and ultimately a cryo-electron microscopic structure; (iii) the physiological consequences of 6S RNA function through identification of the 6S RNA regulon and promoter features that determine 6S RNA sensitivity; and (iv) the mechanism and cellular impact of 6S RNA-directed synthesis of product RNAs (i.e., pRNA synthesis). Much has been learned about this unusual RNA, its mechanism of action, and how it is regulated; yet much still remains to be investigated, especially regarding potential differences in behavior of 6S RNAs in diverse bacteria.
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Affiliation(s)
- Karen M Wassarman
- Department of Bacteriology, University of Wisconsin-Madison, Madison, WI 53562
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18
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Legionella quorum sensing and its role in pathogen–host interactions. Curr Opin Microbiol 2018; 41:29-35. [DOI: 10.1016/j.mib.2017.11.010] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2017] [Revised: 11/06/2017] [Accepted: 11/07/2017] [Indexed: 12/21/2022]
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Elkina D, Weber L, Lechner M, Burenina O, Weisert A, Kubareva E, Hartmann RK, Klug G. 6S RNA in Rhodobacter sphaeroides: 6S RNA and pRNA transcript levels peak in late exponential phase and gene deletion causes a high salt stress phenotype. RNA Biol 2017; 14:1627-1637. [PMID: 28692405 DOI: 10.1080/15476286.2017.1342933] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
Abstract
The function of 6S RNA, a global regulator of transcription, was studied in the photosynthetic α-proteobacterium Rhodobacter sphaeroides. The cellular levels of R. sphaeroides 6S RNA peak toward the transition to stationary phase and strongly decrease during extended stationary phase. The synthesis of so-called product RNA transcripts (mainly 12-16-mers) on 6S RNA as template by RNA polymerase was found to be highest in late exponential phase. Product RNA ≥ 13-mers are expected to trigger the dissociation of 6S RNA:RNA polymerase complexes. A 6S RNA deletion in R. sphaeroides had no impact on growth under various metabolic and oxidative stress conditions (with the possible exception of tert-butyl hydroperoxide stress). However, the 6S RNA knockout resulted in a robust growth defect under high salt stress (0.25 M NaCl). Remarkably, the sspA gene encoding the putative salt stress-induced membrane protein SspA and located immediately downstream of the 6S RNA (ssrS) gene on the antisense strand was expressed at elevated levels in the ΔssrS strain when grown in the presence of 250 mM NaCl.
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Affiliation(s)
- Daria Elkina
- a Chemistry Department and A.N. Belozersky Institute of Physico-Chemical Biology , M.V. Lomonosov Moscow State University , Leninskie Gory 1, Moscow , Russia
| | - Lennart Weber
- b Institut für Mikrobiologie und Molekularbiologie, Justus-Liebig-University-Gießen, Heinrich-Buff-Ring 26-32 , Gießen , Germany
| | - Marcus Lechner
- c Institut für Pharmazeutische Chemie, Philipps-Universität Marburg, Marbacher Weg 6 , Marburg , Germany ; Skolkovo Institute for Science and Technology , Skoltech, Moscow
| | - Olga Burenina
- a Chemistry Department and A.N. Belozersky Institute of Physico-Chemical Biology , M.V. Lomonosov Moscow State University , Leninskie Gory 1, Moscow , Russia
| | - Andrea Weisert
- b Institut für Mikrobiologie und Molekularbiologie, Justus-Liebig-University-Gießen, Heinrich-Buff-Ring 26-32 , Gießen , Germany
| | - Elena Kubareva
- a Chemistry Department and A.N. Belozersky Institute of Physico-Chemical Biology , M.V. Lomonosov Moscow State University , Leninskie Gory 1, Moscow , Russia
| | - Roland K Hartmann
- c Institut für Pharmazeutische Chemie, Philipps-Universität Marburg, Marbacher Weg 6 , Marburg , Germany ; Skolkovo Institute for Science and Technology , Skoltech, Moscow
| | - Gabriele Klug
- b Institut für Mikrobiologie und Molekularbiologie, Justus-Liebig-University-Gießen, Heinrich-Buff-Ring 26-32 , Gießen , Germany
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Ren J, Sang Y, Qin R, Cui Z, Yao YF. 6S RNA is involved in acid resistance and invasion of epithelial cells in Salmonella enterica serovar Typhimurium. Future Microbiol 2017; 12:1045-1057. [PMID: 28796533 DOI: 10.2217/fmb-2017-0055] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
AIM Acid is an important environmental condition encountered frequently by Salmonella enterica serovar Typhimurium during its pathogenesis, but the role of small-noncoding RNAs (sRNAs) in response to acid stress is poorly understood. METHODS We used RNA sequencing to explore acid-responsive sRNAs in S. Typhimurium. RESULTS It identified that 6S RNA encoded by the ssrS was significantly upregulated at pH 3.0. The 6S RNA knockout strain showed a reduced ability to survive at pH 3.0. Additionally, genes in Salmonella pathogenicity island-1 were downregulated in the 6S RNA knockout strain. The loss of 6S RNA significantly reduced S. Typhimurium invasion ability in HeLa cells and virulence in a mouse model. CONCLUSION These findings demonstrate that 6S RNA plays an important role in S. Typhimurium survival under extremely acid conditions and for invasion of epithelial cells.
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Affiliation(s)
- Jie Ren
- Department of Microbiology & Immunology, Laboratory of Bacterial Pathogenesis, Institutes of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Yu Sang
- Department of Microbiology & Immunology, Laboratory of Bacterial Pathogenesis, Institutes of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Ran Qin
- Key Laboratory of Agricultural Environmental Microbiology, Ministry of Agriculture, Department of Microbiology, College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, China
| | - Zhongli Cui
- Key Laboratory of Agricultural Environmental Microbiology, Ministry of Agriculture, Department of Microbiology, College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, China
| | - Yu-Feng Yao
- Department of Microbiology & Immunology, Laboratory of Bacterial Pathogenesis, Institutes of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China.,Department of Laboratory Medicine, Shanghai East Hospital, Tongji University School of Medicine, Shanghai 200120, China
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Abstract
Bacterial pathogens must endure or adapt to different environments and stresses during transmission and infection. Posttranscriptional gene expression control by regulatory RNAs, such as small RNAs and riboswitches, is now considered central to adaptation in many bacteria, including pathogens. The study of RNA-based regulation (riboregulation) in pathogenic species has provided novel insight into how these bacteria regulate virulence gene expression. It has also uncovered diverse mechanisms by which bacterial small RNAs, in general, globally control gene expression. Riboregulators as well as their targets may also prove to be alternative targets or provide new strategies for antimicrobials. In this article, we present an overview of the general mechanisms that bacteria use to regulate with RNA, focusing on examples from pathogens. In addition, we also briefly review how deep sequencing approaches have aided in opening new perspectives in small RNA identification and the study of their functions. Finally, we discuss examples of riboregulators in two model pathogens that control virulence factor expression or survival-associated phenotypes, such as stress tolerance, biofilm formation, or cell-cell communication, to illustrate how riboregulation factors into regulatory networks in bacterial pathogens.
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Legionella pneumophila OxyR Is a Redundant Transcriptional Regulator That Contributes to Expression Control of the Two-Component CpxRA System. J Bacteriol 2017; 199:JB.00690-16. [PMID: 27994017 DOI: 10.1128/jb.00690-16] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Accepted: 12/13/2016] [Indexed: 12/27/2022] Open
Abstract
Nominally an environmental organism, Legionella pneumophila is an intracellular parasite of protozoa but is also the causative agent of the pneumonia termed Legionnaires' disease, which results from inhalation of aerosolized bacteria by susceptible humans. Coordination of gene expression by a number of identified regulatory factors, including OxyR, assists L. pneumophila in adapting to the stresses of changing environments. L. pneumophila OxyR (OxyRLp) is an ortholog of Escherichia coli OxyR; however, OxyRLp was shown elsewhere to be functionally divergent, such that it acts as a transcription regulator independently of the oxidative stress response. In this study, the use of improved gene deletion methods has enabled us to generate an unmarked in-frame deletion of oxyR in L. pneumophila Lack of OxyRLp did not affect in vitro growth or intracellular growth in Acanthamoeba castellanii protozoa and U937-derived macrophages. The expression of OxyRLp does not appear to be regulated by CpxR, even though purified recombinant CpxR bound a DNA sequence similar to that reported for CpxR elsewhere. Surprisingly, a lack of OxyRLp resulted in elevated activity of the promoters located upstream of icmR and the lpg1441-cpxA operon, and OxyRLp directly bound to these promoter regions, suggesting that OxyRLp is a direct repressor. Interestingly, a strain overexpressing OxyRLp demonstrated reduced intracellular growth in A. castellanii but not in U937-derived macrophages, suggesting that balanced expression control of the two-component CpxRA system is necessary for survival in protozoa. Taken together, this study suggests that OxyRLp is a functionally redundant transcriptional regulator in L. pneumophila under the conditions evaluated herein.IMPORTANCELegionella pneumophila is an environmental pathogen, with its transmission to the human host dependent upon its ability to replicate in protozoa and survive within its aquatic niche. Understanding the genetic factors that contribute to L. pneumophila survival within each of these unique environments will be key to limiting future point-source outbreaks of Legionnaires' disease. The transcriptional regulator L. pneumophila OxyR (OxyRLp) has been previously identified as a potential regulator of virulence traits warranting further investigation. This study demonstrated that oxyR is nonessential for L. pneumophila survival in vitro and in vivo via mutational analysis. While the mechanisms of how OxyRLp expression is regulated remain elusive, this study shows that OxyRLp negatively regulates the expression of the cpxRA two-component system necessary for intracellular survival in protozoa.
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Ahmed W, Zheng K, Liu ZF. Small Non-Coding RNAs: New Insights in Modulation of Host Immune Response by Intracellular Bacterial Pathogens. Front Immunol 2016; 7:431. [PMID: 27803700 PMCID: PMC5067535 DOI: 10.3389/fimmu.2016.00431] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2016] [Accepted: 10/03/2016] [Indexed: 12/20/2022] Open
Abstract
Pathogenic bacteria possess intricate regulatory networks that temporally control the production of virulence factors and enable the bacteria to survive and proliferate within host cell. Small non-coding RNAs (sRNAs) have been identified as important regulators of gene expression in diverse biological contexts. Recent research has shown bacterial sRNAs involved in growth and development, cell proliferation, differentiation, metabolism, cell signaling, and immune response through regulating protein–protein interactions or via their ability to base pair with RNA and DNA. In this review, we provide a brief overview of mechanism of action employed by immune-related sRNAs, their known functions in immunity, and how they can be integrated into regulatory circuits that govern virulence, which will facilitate our understanding of pathogenesis and the development of novel, more effective therapeutic approaches to treat infections caused by intracellular bacterial pathogens.
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Affiliation(s)
- Waqas Ahmed
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University , Wuhan , China
| | - Ke Zheng
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University , Wuhan , China
| | - Zheng-Fei Liu
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University , Wuhan , China
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Schroeder CLC, Narra HP, Rojas M, Sahni A, Patel J, Khanipov K, Wood TG, Fofanov Y, Sahni SK. Bacterial small RNAs in the Genus Rickettsia. BMC Genomics 2015; 16:1075. [PMID: 26679185 PMCID: PMC4683814 DOI: 10.1186/s12864-015-2293-7] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2015] [Accepted: 12/14/2015] [Indexed: 01/02/2023] Open
Abstract
Background Rickettsia species are obligate intracellular Gram-negative pathogenic bacteria and the etiologic agents of diseases such as Rocky Mountain spotted fever (RMSF), Mediterranean spotted fever, epidemic typhus, and murine typhus. Genome sequencing revealed that R. prowazekii has ~25 % non-coding DNA, the majority of which is thought to be either “junk DNA” or pseudogenes resulting from genomic reduction. These characteristics also define other Rickettsia genomes. Bacterial small RNAs, whose biogenesis is predominantly attributed to either the intergenic regions (trans-acting) or to the antisense strand of an open reading frame (cis-acting), are now appreciated to be among the most important post-transcriptional regulators of bacterial virulence and growth. We hypothesize that intergenic regions in rickettsial species encode for small, non-coding RNAs (sRNAs) involved in the regulation of its transcriptome, leading to altered virulence and adaptation depending on the host niche. Results We employed a combination of bioinformatics and in vitro approaches to explore the presence of sRNAs in a number of species within Genus Rickettsia. Using the sRNA Identification Protocol using High-throughput Technology (SIPHT) web interface, we predicted over 1,700 small RNAs present in the intergenic regions of 16 different strains representing 13 rickettsial species. We further characterized novel sRNAs from typhus (R. prowazekii and R. typhi) and spotted fever (R. rickettsii and R. conorii) groups for their promoters and Rho-independent terminators using Bacterial Promoter Prediction Program (BPROM) and TransTermHP prediction algorithms, respectively. Strong σ70 promoters were predicted upstream of all novel small RNAs, indicating the potential for transcriptional activity. Next, we infected human microvascular endothelial cells (HMECs) with R. prowazekii for 3 h and 24 h and performed Next Generation Sequencing to experimentally validate the expression of 26 sRNA candidates predicted in R. prowazekii. Reverse transcriptase PCR was also used to further verify the expression of six putative novel sRNA candidates in R. prowazekii. Conclusions Our results yield clear evidence for the expression of novel R. prowazekii sRNA candidates during infection of HMECs. This is the first description of novel small RNAs for a highly pathogenic species of Rickettsia, which should lead to new insights into rickettsial virulence and adaptation mechanisms. Electronic supplementary material The online version of this article (doi:10.1186/s12864-015-2293-7) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Casey L C Schroeder
- Department of Pathology, the University of Texas Medical Branch, 301 University Blvd, Galveston, TX, 77555, USA.
| | - Hema P Narra
- Department of Pathology, the University of Texas Medical Branch, 301 University Blvd, Galveston, TX, 77555, USA.
| | - Mark Rojas
- Department of Pharmacology, the University of Texas Medical Branch, 301 University Blvd, Galveston, TX, 77555, USA.
| | - Abha Sahni
- Department of Pathology, the University of Texas Medical Branch, 301 University Blvd, Galveston, TX, 77555, USA.
| | - Jignesh Patel
- Department of Pathology, the University of Texas Medical Branch, 301 University Blvd, Galveston, TX, 77555, USA.
| | - Kamil Khanipov
- Department of Pharmacology, the University of Texas Medical Branch, 301 University Blvd, Galveston, TX, 77555, USA.
| | - Thomas G Wood
- Department of Biochemistry and Molecular Biology, the University of Texas Medical Branch, 301 University Blvd, Galveston, TX, 77555, USA.
| | - Yuriy Fofanov
- Department of Pharmacology, the University of Texas Medical Branch, 301 University Blvd, Galveston, TX, 77555, USA.
| | - Sanjeev K Sahni
- Department of Pathology, the University of Texas Medical Branch, 301 University Blvd, Galveston, TX, 77555, USA.
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Schell U, Simon S, Sahr T, Hager D, Albers MF, Kessler A, Fahrnbauer F, Trauner D, Hedberg C, Buchrieser C, Hilbi H. The α-hydroxyketone LAI-1 regulates motility, Lqs-dependent phosphorylation signalling and gene expression ofLegionella pneumophila. Mol Microbiol 2015; 99:778-93. [DOI: 10.1111/mmi.13265] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/02/2015] [Indexed: 12/29/2022]
Affiliation(s)
- Ursula Schell
- Max von Pettenkofer Institute; Ludwig-Maximilians University; Pettenkoferstraße 9a 80336 Munich Germany
| | - Sylvia Simon
- Max von Pettenkofer Institute; Ludwig-Maximilians University; Pettenkoferstraße 9a 80336 Munich Germany
- Institute of Medical Microbiology; University of Zürich; Gloriastrasse 30/32 8006 Zürich Switzerland
| | - Tobias Sahr
- Institut Pasteur; Unité de Biologie des Bactéries Intracellulaires; Paris France
- CNRS UMR 3525; 28 Rue du Dr Roux 75724 Paris France
| | - Dominik Hager
- Department of Chemistry; Ludwig-Maximilians University; Butenandtstrasse 5-13, Building F 81377 Munich Germany
| | - Michael F. Albers
- Chemical Biology Center (KBC); Institute of Chemistry; Umeå University; S-90187 Umeå Sweden
| | - Aline Kessler
- Max von Pettenkofer Institute; Ludwig-Maximilians University; Pettenkoferstraße 9a 80336 Munich Germany
| | - Felix Fahrnbauer
- Department of Chemistry; Ludwig-Maximilians University; Butenandtstrasse 5-13, Building F 81377 Munich Germany
| | - Dirk Trauner
- Department of Chemistry; Ludwig-Maximilians University; Butenandtstrasse 5-13, Building F 81377 Munich Germany
| | - Christian Hedberg
- Chemical Biology Center (KBC); Institute of Chemistry; Umeå University; S-90187 Umeå Sweden
| | - Carmen Buchrieser
- Institut Pasteur; Unité de Biologie des Bactéries Intracellulaires; Paris France
- CNRS UMR 3525; 28 Rue du Dr Roux 75724 Paris France
| | - Hubert Hilbi
- Max von Pettenkofer Institute; Ludwig-Maximilians University; Pettenkoferstraße 9a 80336 Munich Germany
- Institute of Medical Microbiology; University of Zürich; Gloriastrasse 30/32 8006 Zürich Switzerland
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26
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Burenina OY, Elkina DA, Hartmann RK, Oretskaya TS, Kubareva EA. Small noncoding 6S RNAs of bacteria. BIOCHEMISTRY (MOSCOW) 2015; 80:1429-46. [DOI: 10.1134/s0006297915110048] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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27
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Abstract
6S RNA is a highly abundant small non-coding RNA widely spread among diverse bacterial groups. By competing with DNA promoters for binding to RNA polymerase (RNAP), the RNA regulates transcription on a global scale. RNAP produces small product RNAs derived from 6S RNA as template, which rearranges the 6S RNA structure leading to dissociation of 6S RNA:RNAP complexes. Although 6S RNA has been experimentally analysed in detail for some species, such as Escherichia coli and Bacillus subtilis, and was computationally predicted in many diverse bacteria, a complete and up-to-date overview of the distribution among all bacteria is missing. In this study we searched with new methods for 6S RNA genes in all currently available bacterial genomes. We ended up with a set of 1,750 6S RNA genes, of which 1,367 are novel and bona fide, distributed among 1,610 bacteria, and had a few tentative candidates among the remaining 510 assembled bacterial genomes accessible. We were able to confirm two tentative candidates by Northern blot analysis. We extended 6S RNA genes of the Flavobacteriia significantly in length compared to the present Rfam entry. We describe multiple homologs of 6S RNAs (including split 6S RNA genes) and performed a detailed synteny analysis.
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Affiliation(s)
- Stefanie Wehner
- a Department for Bioinformatics; Faculty of Mathematics and Computer Science ; Friedrich-Schiller-University of Jena , Jena , Germany
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28
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Li L, Mendis N, Trigui H, Faucher SP. Transcriptomic changes of Legionella pneumophila in water. BMC Genomics 2015; 16:637. [PMID: 26306795 PMCID: PMC4549902 DOI: 10.1186/s12864-015-1869-6] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2015] [Accepted: 08/19/2015] [Indexed: 11/10/2022] Open
Abstract
Background Legionella pneumophila (Lp) is a water-borne opportunistic pathogen. In water, Lp can survive for an extended period of time until it encounters a permissive host. Therefore, identifying genes that are required for survival in water may help develop strategies to prevent Legionella outbreaks. Results We compared the global transcriptomic response of Lp grown in a rich medium to that of Lp exposed to an artificial freshwater medium (Fraquil) for 2, 6 and 24 hours. We uncovered successive changes in gene expression required for the successful adaptation to a nutrient-limited water environment. The repression of major pathways involved in cell division, transcription and translation, suggests that Lp enters a quiescent state in water. The induction of flagella associated genes (flg, fli and mot), enhanced-entry genes (enh) and some Icm/Dot effector genes suggests that Lp is primed to invade a suitable host in response to water exposure. Moreover, many genes involved in resistance to antibiotic and oxidative stress were induced, suggesting that Lp may be more tolerant to these stresses in water. Indeed, Lp exposed to water is more resistant to erythromycin, gentamycin and kanamycin than Lp cultured in rich medium. In addition, the bdhA gene, involved in the degradation pathway of the intracellular energy storage compound polyhydroxybutyrate, is also highly expressed in water. Further characterization show that expression of bdhA during short-term water exposure is dependent upon RpoS, which is required for the survival of Lp in water. Deletion of bdhA reduces the survival of Lp in water at 37 °C. Conclusions The increase of antibiotic resistance and the importance of bdhA to the survival of Lp in water seem consistent with the observed induction of these genes when Lp is exposed to water. Other genes that are highly induced upon exposure to water could also be necessary for Lp to maintain viability in the water environment. Electronic supplementary material The online version of this article (doi:10.1186/s12864-015-1869-6) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Laam Li
- Department of Natural Resource Sciences, Faculty of Agricultural and Environmental Sciences, McGill University, 21,111 Lakeshore Road, Ste-Anne-de-Bellevue, Montreal, QC, H9X 3V9, Canada.
| | - Nilmini Mendis
- Department of Natural Resource Sciences, Faculty of Agricultural and Environmental Sciences, McGill University, 21,111 Lakeshore Road, Ste-Anne-de-Bellevue, Montreal, QC, H9X 3V9, Canada.
| | - Hana Trigui
- Department of Natural Resource Sciences, Faculty of Agricultural and Environmental Sciences, McGill University, 21,111 Lakeshore Road, Ste-Anne-de-Bellevue, Montreal, QC, H9X 3V9, Canada.
| | - Sébastien P Faucher
- Department of Natural Resource Sciences, Faculty of Agricultural and Environmental Sciences, McGill University, 21,111 Lakeshore Road, Ste-Anne-de-Bellevue, Montreal, QC, H9X 3V9, Canada.
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Oliva G, Sahr T, Buchrieser C. Small RNAs, 5′ UTR elements and RNA-binding proteins in intracellular bacteria: impact on metabolism and virulence. FEMS Microbiol Rev 2015; 39:331-349. [DOI: 10.1093/femsre/fuv022] [Citation(s) in RCA: 83] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/30/2023] Open
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Hoch PG, Burenina OY, Weber MHW, Elkina DA, Nesterchuk MV, Sergiev PV, Hartmann RK, Kubareva EA. Phenotypic characterization and complementation analysis of Bacillus subtilis 6S RNA single and double deletion mutants. Biochimie 2015; 117:87-99. [PMID: 25576829 DOI: 10.1016/j.biochi.2014.12.019] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2014] [Accepted: 12/22/2014] [Indexed: 10/24/2022]
Abstract
6S RNA, a global regulator of transcription in bacteria, binds to housekeeping RNA polymerase (RNAP) holoenzymes to competitively inhibit transcription from DNA promoters. Bacillus subtilis encodes two 6S RNA homologs whose differential functions are as yet unclear. We constructed derivative strains of B. subtilis PY79 lacking 6S-1 RNA (ΔbsrA), 6S-2 RNA (ΔbsrB) or both (ΔbsrAB) to study the physiological role of the two 6S RNAs. We observed two growth phenotypes of mutant strains: (i) accelerated decrease of optical density toward extended stationary phase and (ii) faster outgrowth from stationary phase under alkaline stress conditions (pH 9.8). The first phenotype was observed for bacteria lacking bsrA, and even more pronounced for ΔbsrAB bacteria, but not for those lacking bsrB. The magnitude of the second phenotype was relatively weak for ΔbsrB, moderate for ΔbsrA and again strongest for ΔbsrAB bacteria. Whereas ΔbsrAB bacteria complemented with bsrB or bsrA (strains ΔbsrAB + B and ΔbsrAB + A) mimicked the phenotypes of the ΔbsrA and ΔbsrB strains, respectively, complementation with the gene ssrS encoding Escherichia coli 6S RNA failed to cure the "low stationary optical density" phenotype of the double mutant, despite ssrS expression, in line with previous findings. Finally, proteomics (two-dimensional differential gel electrophoresis, 2D-DIGE) of B. subtilis 6S RNA deletion strains unveiled a set of proteins that were expressed at higher levels particularly during exponential growth and preferentially in mutant strains lacking 6S-2 RNA. Several of these proteins are involved in metabolism and stress responses.
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Affiliation(s)
- Philipp G Hoch
- Philipps-Universität Marburg, Fachbereich Pharmazie, Institut für Pharmazeutische Chemie, Marbacher Weg 6, D-35037 Marburg, Germany.
| | - Olga Y Burenina
- Chemistry Department and A.N. Belozersky Institute of Physico-Chemical Biology, M.V. Lomonosov Moscow State University, Leninskie Gory 1, 119991 Moscow, Russia.
| | - Michael H W Weber
- Philipps-Universität Marburg, Fachbereich Pharmazie, Institut für Pharmazeutische Chemie, Marbacher Weg 6, D-35037 Marburg, Germany.
| | - Daria A Elkina
- Chemistry Department and A.N. Belozersky Institute of Physico-Chemical Biology, M.V. Lomonosov Moscow State University, Leninskie Gory 1, 119991 Moscow, Russia.
| | - Mikhail V Nesterchuk
- Chemistry Department and A.N. Belozersky Institute of Physico-Chemical Biology, M.V. Lomonosov Moscow State University, Leninskie Gory 1, 119991 Moscow, Russia.
| | - Petr V Sergiev
- Chemistry Department and A.N. Belozersky Institute of Physico-Chemical Biology, M.V. Lomonosov Moscow State University, Leninskie Gory 1, 119991 Moscow, Russia.
| | - Roland K Hartmann
- Philipps-Universität Marburg, Fachbereich Pharmazie, Institut für Pharmazeutische Chemie, Marbacher Weg 6, D-35037 Marburg, Germany.
| | - Elena A Kubareva
- Chemistry Department and A.N. Belozersky Institute of Physico-Chemical Biology, M.V. Lomonosov Moscow State University, Leninskie Gory 1, 119991 Moscow, Russia.
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Ortega AD, Quereda JJ, Pucciarelli MG, García-del Portillo F. Non-coding RNA regulation in pathogenic bacteria located inside eukaryotic cells. Front Cell Infect Microbiol 2014; 4:162. [PMID: 25429360 PMCID: PMC4228915 DOI: 10.3389/fcimb.2014.00162] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2014] [Accepted: 10/20/2014] [Indexed: 01/06/2023] Open
Abstract
Intracellular bacterial pathogens have evolved distinct lifestyles inside eukaryotic cells. Some pathogens coexist with the infected cell in an obligate intracellular state, whereas others transit between the extracellular and intracellular environment. Adaptation to these intracellular lifestyles is regulated in both space and time. Non-coding small RNAs (sRNAs) are post-transcriptional regulatory molecules that fine-tune important processes in bacterial physiology including cell envelope architecture, intermediate metabolism, bacterial communication, biofilm formation, and virulence. Recent studies have shown production of defined sRNA species by intracellular bacteria located inside eukaryotic cells. The molecules targeted by these sRNAs and their expression dynamics along the intracellular infection cycle remain, however, poorly characterized. Technical difficulties linked to the isolation of “intact” intracellular bacteria from infected host cells might explain why sRNA regulation in these specialized pathogens is still a largely unexplored field. Transition from the extracellular to the intracellular lifestyle provides an ideal scenario in which regulatory sRNAs are intended to participate; so much work must be done in this direction. This review focuses on sRNAs expressed by intracellular bacterial pathogens during the infection of eukaryotic cells, strategies used with these pathogens to identify sRNAs required for virulence, and the experimental technical challenges associated to this type of studies. We also discuss varied techniques for their potential application to study RNA regulation in intracellular bacterial infections.
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Affiliation(s)
- Alvaro D Ortega
- Centro Nacional de Biotecnología - Consejo Superior de Investigaciones Científicas (CNB-CSIC) Madrid, Spain
| | - Juan J Quereda
- Centro Nacional de Biotecnología - Consejo Superior de Investigaciones Científicas (CNB-CSIC) Madrid, Spain
| | - M Graciela Pucciarelli
- Centro Nacional de Biotecnología - Consejo Superior de Investigaciones Científicas (CNB-CSIC) Madrid, Spain ; Departamento de Biología Molecular, Universidad Autónoma de Madrid, Centro de Biología Molecular 'Severo Ochoa' (CBMSO-CSIC) Madrid, Spain
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Caswell CC, Oglesby-Sherrouse AG, Murphy ER. Sibling rivalry: related bacterial small RNAs and their redundant and non-redundant roles. Front Cell Infect Microbiol 2014; 4:151. [PMID: 25389522 PMCID: PMC4211561 DOI: 10.3389/fcimb.2014.00151] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2014] [Accepted: 10/07/2014] [Indexed: 11/13/2022] Open
Abstract
Small RNA molecules (sRNAs) are now recognized as key regulators controlling bacterial gene expression, as sRNAs provide a quick and efficient means of positively or negatively altering the expression of specific genes. To date, numerous sRNAs have been identified and characterized in a myriad of bacterial species, but more recently, a theme in bacterial sRNAs has emerged: the presence of more than one highly related sRNAs produced by a given bacterium, here termed sibling sRNAs. Sibling sRNAs are those that are highly similar at the nucleotide level, and while it might be expected that sibling sRNAs exert identical regulatory functions on the expression of target genes based on their high degree of relatedness, emerging evidence is demonstrating that this is not always the case. Indeed, there are several examples of bacterial sibling sRNAs with non-redundant regulatory functions, but there are also instances of apparent regulatory redundancy between sibling sRNAs. This review provides a comprehensive overview of the current knowledge of bacterial sibling sRNAs, and also discusses important questions about the significance and evolutionary implications of this emerging class of regulators.
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Affiliation(s)
- Clayton C Caswell
- Department of Biomedical Sciences and Pathobiology, Center for Molecular Medicine and Infectious Diseases, VA-MD Regional College of Veterinary Medicine, Virginia Tech Blacksburg, VA, USA
| | - Amanda G Oglesby-Sherrouse
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland Baltimore, MD, USA ; Department of Microbiology and Immunology, School of Medicine, University of Maryland Baltimore, MD, USA
| | - Erin R Murphy
- Department of Biomedical Sciences, Ohio University Heritage College of Osteopathic Medicine Athens, OH, USA
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Hnilicová J, Jirát Matějčková J, Šiková M, Pospíšil J, Halada P, Pánek J, Krásný L. Ms1, a novel sRNA interacting with the RNA polymerase core in mycobacteria. Nucleic Acids Res 2014; 42:11763-76. [PMID: 25217589 PMCID: PMC4191392 DOI: 10.1093/nar/gku793] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2014] [Revised: 08/19/2014] [Accepted: 08/20/2014] [Indexed: 11/12/2022] Open
Abstract
Small RNAs (sRNAs) are molecules essential for a number of regulatory processes in the bacterial cell. Here we characterize Ms1, a sRNA that is highly expressed in Mycobacterium smegmatis during stationary phase of growth. By glycerol gradient ultracentrifugation, RNA binding assay, and RNA co-immunoprecipitation, we show that Ms1 interacts with the RNA polymerase (RNAP) core that is free of the primary sigma factor (σA) or any other σ factor. This contrasts with the situation in most other species where it is 6S RNA that interacts with RNAP and this interaction requires the presence of σA. The difference in the interaction of the two types of sRNAs (Ms1 or 6S RNA) with RNAP possibly reflects the difference in the composition of the transcriptional machinery between mycobacteria and other species. Unlike Escherichia coli, stationary phase M. smegmatis cells contain relatively few RNAP molecules in complex with σA. Thus, Ms1 represents a novel type of small RNAs interacting with RNAP.
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Affiliation(s)
- Jarmila Hnilicová
- Department of Molecular Genetics of Bacteria, Institute of Microbiology, Academy of Sciences of the Czech Republic, Prague 142 20, Czech Republic
| | - Jitka Jirát Matějčková
- Department of Molecular Genetics of Bacteria, Institute of Microbiology, Academy of Sciences of the Czech Republic, Prague 142 20, Czech Republic
| | - Michaela Šiková
- Department of Molecular Genetics of Bacteria, Institute of Microbiology, Academy of Sciences of the Czech Republic, Prague 142 20, Czech Republic
| | - Jiří Pospíšil
- Department of Molecular Genetics of Bacteria, Institute of Microbiology, Academy of Sciences of the Czech Republic, Prague 142 20, Czech Republic
| | - Petr Halada
- Department of Molecular Structure Characterization, Institute of Microbiology, Academy of Sciences of the Czech Republic, Prague 142 20, Czech Republic
| | - Josef Pánek
- Department of Bioinformatics, Institute of Microbiology, Academy of Sciences of the Czech Republic, Prague 142 20, Czech Republic
| | - Libor Krásný
- Department of Molecular Genetics of Bacteria, Institute of Microbiology, Academy of Sciences of the Czech Republic, Prague 142 20, Czech Republic
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Mendis N, Lin YR, Faucher SP. Comparison of virulence properties of Pseudomonas aeruginosa exposed to water and grown in rich broth. Can J Microbiol 2014; 60:777-81. [PMID: 25352257 DOI: 10.1139/cjm-2014-0519] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Pseudomonas aeruginosa is an opportunistic pathogen that can infect susceptible patients suffering from cystic fibrosis, immunosuppression, and severe burns. Nosocomial- and community-acquired infection is likely due to contact with water sources contaminated with P. aeruginosa. Most of what is known about the virulence properties of P. aeruginosa was derived from studies using fairly rich broths, which do not represent conditions found in water, such as low nutrient concentrations. Here, we compare biofilm production, invasion of epithelial cells, cytotoxicity, and pyocyanin production of P. aeruginosa in water with P. aeruginosa grown in rich broth. Since tap water is variable, we used a defined water medium, Fraquil, to ensure reproducibility of the results. We found that P. aeruginosa does not readily form biofilm in Fraquil. Pseudomonas aeruginosa is equally able to attach to and invade epithelial cells but is more cytotoxic after incubation in water for 30 days than when it is grown in rich broth. Moreover, P. aeruginosa produces less pyocyanin when exposed to water. Our results show that P. aeruginosa seems to have different properties when exposed to water than when grown in rich broth.
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Affiliation(s)
- Nilmini Mendis
- Department of Natural Resource Sciences, Faculty of Agricultural and Environmental Sciences, Macdonald Campus, McGill University, 21 111 Lakeshore Road, Ste-Anne-de-Bellevue, QC H9X 3V9, Canada
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Cavanagh AT, Wassarman KM. 6S RNA, a Global Regulator of Transcription inEscherichia coli,Bacillus subtilis, and Beyond. Annu Rev Microbiol 2014; 68:45-60. [DOI: 10.1146/annurev-micro-092611-150135] [Citation(s) in RCA: 82] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Amy T. Cavanagh
- Department of Bacteriology, University of Wisconsin–Madison, Madison, Wisconsin 53706;
| | - Karen M. Wassarman
- Department of Bacteriology, University of Wisconsin–Madison, Madison, Wisconsin 53706;
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36
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Identification of novel small RNAs and characterization of the 6S RNA of Coxiella burnetii. PLoS One 2014; 9:e100147. [PMID: 24949863 PMCID: PMC4064990 DOI: 10.1371/journal.pone.0100147] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2014] [Accepted: 05/20/2014] [Indexed: 11/30/2022] Open
Abstract
Coxiella burnetii, an obligate intracellular bacterial pathogen that causes Q fever, undergoes a biphasic developmental cycle that alternates between a metabolically-active large cell variant (LCV) and a dormant small cell variant (SCV). As such, the bacterium undoubtedly employs complex modes of regulating its lifecycle, metabolism and pathogenesis. Small RNAs (sRNAs) have been shown to play important regulatory roles in controlling metabolism and virulence in several pathogenic bacteria. We hypothesize that sRNAs are involved in regulating growth and development of C. burnetii and its infection of host cells. To address the hypothesis and identify potential sRNAs, we subjected total RNA isolated from Coxiella cultured axenically and in Vero host cells to deep-sequencing. Using this approach, we identified fifteen novel C. burnetii sRNAs (CbSRs). Fourteen CbSRs were validated by Northern blotting. Most CbSRs showed differential expression, with increased levels in LCVs. Eight CbSRs were upregulated (≥2-fold) during intracellular growth as compared to growth in axenic medium. Along with the fifteen sRNAs, we also identified three sRNAs that have been previously described from other bacteria, including RNase P RNA, tmRNA and 6S RNA. The 6S regulatory sRNA of C. burnetii was found to accumulate over log phase-growth with a maximum level attained in the SCV stage. The 6S RNA-encoding gene (ssrS) was mapped to the 5′ UTR of ygfA; a highly conserved linkage in eubacteria. The predicted secondary structure of the 6S RNA possesses three highly conserved domains found in 6S RNAs of other eubacteria. We also demonstrate that Coxiella’s 6S RNA interacts with RNA polymerase (RNAP) in a specific manner. Finally, transcript levels of 6S RNA were found to be at much higher levels when Coxiella was grown in host cells relative to axenic culture, indicating a potential role in regulating the bacterium’s intracellular stress response by interacting with RNAP during transcription.
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Vercruysse M, Köhrer C, Davies BW, Arnold MFF, Mekalanos JJ, RajBhandary UL, Walker GC. The highly conserved bacterial RNase YbeY is essential in Vibrio cholerae, playing a critical role in virulence, stress regulation, and RNA processing. PLoS Pathog 2014; 10:e1004175. [PMID: 24901994 PMCID: PMC4047096 DOI: 10.1371/journal.ppat.1004175] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2014] [Accepted: 04/24/2014] [Indexed: 11/18/2022] Open
Abstract
YbeY, a highly conserved protein, is an RNase in E. coli and plays key roles in both processing of the critical 3′ end of 16 S rRNA and in 70 S ribosome quality control under stress. These central roles account for YbeY's inclusion in the postulated minimal bacterial genome. However, YbeY is not essential in E. coli although loss of ybeY severely sensitizes it to multiple physiological stresses. Here, we show that YbeY is an essential endoribonuclease in Vibrio cholerae and is crucial for virulence, stress regulation, RNA processing and ribosome quality control, and is part of a core set of RNases essential in most representative pathogens. To understand its function, we analyzed the rRNA and ribosome profiles of a V. cholerae strain partially depleted for YbeY and other RNase mutants associated with 16 S rRNA processing; our results demonstrate that YbeY is also crucial for 16 S rRNA 3′ end maturation in V. cholerae and that its depletion impedes subunit assembly into 70 S ribosomes. YbeY's importance to V. cholerae pathogenesis was demonstrated by the complete loss of mice colonization and biofilm formation, reduced cholera toxin production, and altered expression levels of virulence-associated small RNAs of a V. cholerae strain partially depleted for YbeY. Notably, the ybeY genes of several distantly related pathogens can fully complement an E. coli ΔybeY strain under various stress conditions, demonstrating the high conservation of YbeY's activity in stress regulation. Taken together, this work provides the first comprehensive exploration of YbeY's physiological role in a human pathogen, showing its conserved function across species in essential cellular processes. Bacteria adapt and survive unfavorable environments by quickly changing their gene expression and physiology, for example as pathogens do during infection of host cells. Gene expression is often determined by RNA turnover, a balance between transcription and RNA decay carried out by multiple RNases. The recently identified RNase YbeY was shown in E. coli to participate in rRNA maturation and 70 S ribosome quality control, however YbeY's roles in other organisms and the extent of functional conservation is unknown. Here, we show that YbeY is an essential RNase in the pathogen Vibrio cholerae, critical for cell fitness and general stress tolerance. We demonstrate that YbeY is crucial for 16 S rRNA 3′ end maturation, assembly of functional 70 S ribosomes and ribosome quality control. Moreover, YbeY regulates virulence-associated small RNAs and its depletion leads to an overall reduction in pathogenesis, exemplified by significantly decreased biofilm formation, mouse colonization and cholera toxin production. We also show that YbeY belongs to a minimal core set of RNases essential in most representative pathogens. The multifaceted roles of YbeY in several essential cellular processes and its highly conserved function across bacterial species, suggest that YbeY could be an attractive new antimicrobial target.
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Affiliation(s)
- Maarten Vercruysse
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - Caroline Köhrer
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - Bryan W. Davies
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, Texas, United States of America
| | - Markus F. F. Arnold
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - John J. Mekalanos
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, Massachussets, United States of America
| | - Uttam L. RajBhandary
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - Graham C. Walker
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
- * E-mail:
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Mikulík K, Bobek J, Zídková J, Felsberg J. 6S RNA modulates growth and antibiotic production in Streptomyces coelicolor. Appl Microbiol Biotechnol 2014; 98:7185-97. [DOI: 10.1007/s00253-014-5806-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2014] [Revised: 04/26/2014] [Accepted: 04/29/2014] [Indexed: 10/25/2022]
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Nasrallah GK, Abdelhady H, Tompkins NP, Carson KR, Garduño RA. Deletion of potD, encoding a putative spermidine-binding protein, results in a complex phenotype in Legionella pneumophila. Int J Med Microbiol 2014; 304:703-16. [PMID: 24928741 DOI: 10.1016/j.ijmm.2014.05.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2014] [Revised: 03/16/2014] [Accepted: 05/11/2014] [Indexed: 11/28/2022] Open
Abstract
L. pneumophila is an intracellular pathogen that replicates in a membrane-bound compartment known as the Legionella-containing vacuole (LCV). We previously observed that the polyamine spermidine, produced by host cells or added exogenously, enhances the intracellular growth of L. pneumophila. To study this enhancing effect and determine whether polyamines are used as nutrients, we deleted potD from L. pneumophila strain JR32. The gene potD encodes a spermidine-binding protein that in other bacteria is essential for the function of the PotABCD polyamine transporter. Deletion of potD did not affect L. pneumophila growth in vitro in the presence or absence of spermidine and putrescine, suggesting that PotD plays a redundant or no role in polyamine uptake. However, deletion of potD resulted in a puzzlingly complex phenotype that included defects in L. pneumophila's ability to form filaments, tolerate Na(+), associate with macrophages and amoeba, recruit host vesicles to the LCV, and initiate intracellular growth. Moreover, the ΔpotD mutant was completely unable to grow in L929 cells treated with a pharmacological inhibitor of spermidine synthesis. These complex and disparate effects suggest that the L. pneumophila potD encodes either: (i) a multifunctional protein, (ii) a protein that interacts with, or regulates a, multifunctional protein, or (iii) a protein that contributes (directly or indirectly) to a regulatory network. Protein function studies with the L. pneumophila PotD protein are thus warranted.
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Affiliation(s)
- Gheyath K Nasrallah
- Department of Health Sciences, Biomedical Sciences Program, College of Arts and Sciences, Qatar University, Doha, Qatar.
| | - Hany Abdelhady
- Department of Microbiology and Immunology, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Nicholas P Tompkins
- Department of Microbiology and Immunology, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Kaitlyn R Carson
- Department of Microbiology and Immunology, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Rafael A Garduño
- Department of Microbiology and Immunology, Dalhousie University, Halifax, Nova Scotia, Canada; Department of Medicine - Division of Infectious Diseases, Dalhousie University, Halifax, Nova Scotia, Canada
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Steuten B, Hoch PG, Damm K, Schneider S, Köhler K, Wagner R, Hartmann RK. Regulation of transcription by 6S RNAs: insights from the Escherichia coli and Bacillus subtilis model systems. RNA Biol 2014; 11:508-21. [PMID: 24786589 DOI: 10.4161/rna.28827] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Whereas, the majority of bacterial non-coding RNAs and functional RNA elements regulate post-transcriptional processes, either by interacting with other RNAs via base-pairing or through binding of small ligands (riboswitches), 6S RNAs affect transcription itself by binding to the housekeeping holoenzyme of RNA polymerase (RNAP). Remarkably, 6S RNAs serve as RNA templates for bacterial RNAP, giving rise to the de novo synthesis of short transcripts, termed pRNAs (product RNAs). Hence, 6S RNAs prompt the enzyme to act as an RNA-dependent RNA polymerase (RdRP). Synthesis of pRNAs exceeding a certain length limit (~13 nt) persistently rearrange the 6S RNA structure, which in turn, disrupts the 6S RNA:RNAP complex. This pRNA synthesis-mediated "reanimation" of sequestered RNAP molecules represents the conceivably fastest mechanism for resuming transcription in cells that enter a new exponential growth phase. The many different 6S RNAs found in a wide variety of bacteria do not share strong sequence homology but have in common a conserved rod-shaped structure with a large internal loop, termed the central bulge; this architecture mediates specific binding to the active site of RNAP. In this article, we summarize the overall state of knowledge as well as very recent findings on the structure, function, and physiological effects of 6S RNA examples from the two model organisms, Escherichia coli and Bacillus subtilis. Comparison of the presently known properties of 6S RNAs in the two organisms highlights common principles as well as diverse features.
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Affiliation(s)
- Benedikt Steuten
- Heinrich-Heine-Universität Düsseldorf; Institut für Physikalische Biologie Universitätsstr; Düsseldorf, Germany
| | | | - Katrin Damm
- Philipps-Universität Marburg; Marburg, Germany
| | - Sabine Schneider
- Heinrich-Heine-Universität Düsseldorf; Institut für Physikalische Biologie Universitätsstr; Düsseldorf, Germany
| | | | - Rolf Wagner
- Heinrich-Heine-Universität Düsseldorf; Institut für Physikalische Biologie Universitätsstr; Düsseldorf, Germany
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Nitzan M, Wassarman KM, Biham O, Margalit H. Global regulation of transcription by a small RNA: a quantitative view. Biophys J 2014; 106:1205-14. [PMID: 24606944 DOI: 10.1016/j.bpj.2014.01.025] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2013] [Revised: 01/02/2014] [Accepted: 01/10/2014] [Indexed: 11/16/2022] Open
Abstract
Small RNAs are integral regulators of bacterial gene expression, the majority of which act posttranscriptionally by basepairing with target mRNAs, altering translation or mRNA stability. 6S RNA, however, is a small RNA that is a transcriptional regulator, acting by binding directly to σ(70)-RNA polymerase (σ(70)-RNAP) and preventing its binding to gene promoters. At the transition from exponential to stationary phase, 6S RNA accumulates and globally downregulates the transcription of hundreds of genes. At the transition from stationary to exponential phase (outgrowth), 6S RNA is released from σ(70)-RNAP, resulting in a fast increase in free σ(70)-RNAP and transcription of many genes. The transition from stationary to exponential phase is sharp, and is thus accessible for experimental study. However, the transition from exponential to stationary phase is gradual and complicated by changes in other factors, making it more difficult to isolate 6S RNA effects experimentally at this transition. Here, we use mathematical modeling and simulation to study the dynamics of 6S RNA-dependent regulation, focusing on transitions in growth mediated by altered nutrient availability. We first show that our model reproduces the sharp increase in σ(70)-RNAP at outgrowth, as well as the behavior of two experimentally tested mutants, thus justifying its use for characterizing the less accessible dynamics of the transition from exponential to stationary phase. We characterize the dynamics of the two transitions for Escherichia coli wild-type, as well as for mutants with various 6S RNA-RNAP affinities, demonstrating that the 6S RNA regulation mechanism is generally robust to a wide range of such mutations, although the level of regulation at single promoters and their resulting expression fold change will be altered with changes in affinity. Our results provide insight into the potential advantage of transcription regulation by 6S RNA, as it enables storage and efficient release of σ(70)-RNAP during transitions in nutrient availability, which is likely to give a competitive advantage to cells encountering diverse environmental conditions.
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Affiliation(s)
- Mor Nitzan
- Racah Institute of Physics, The Hebrew University, Jerusalem, Israel; Faculty of Medicine, The Hebrew University, Jerusalem, Israel
| | - Karen M Wassarman
- Department of Bacteriology, University of Wisconsin-Madison, Madison, Wisconsin.
| | - Ofer Biham
- Racah Institute of Physics, The Hebrew University, Jerusalem, Israel.
| | - Hanah Margalit
- Faculty of Medicine, The Hebrew University, Jerusalem, Israel.
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Steuten B, Schneider S, Wagner R. 6S RNA: recent answers--future questions. Mol Microbiol 2014; 91:641-8. [PMID: 24308327 DOI: 10.1111/mmi.12484] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/04/2013] [Indexed: 01/31/2023]
Abstract
6S RNA is a non-coding RNA, found in almost all phylogenetic branches of bacteria. Through its conserved secondary structure, resembling open DNA promoters, it binds to RNA polymerase and interferes with transcription at many promoters. That way, it functions as transcriptional regulator facilitating adaptation to stationary phase conditions. Strikingly, 6S RNA acts as template for the synthesis of small RNAs (pRNA), which trigger the disintegration of the inhibitory RNA polymerase-6S RNA complex releasing 6S RNA-dependent repression. The regulatory implications of 6S RNAs vary among different bacterial species depending on the lifestyle and specific growth conditions that they have to face. The influence of 6S RNA can be seen on many different processes including stationary growth, sporulation, light adaptation or intracellular growth of pathogenic bacteria. Recent structural and functional studies have yielded details of the interaction between E. coli 6S RNA and RNA polymerase. Genome-wide transcriptome analyses provided insight into the functional diversity of 6S RNAs. Moreover, the mechanism and physiological consequences of pRNA synthesis have been explored in several systems. A major function of 6S RNA as a guardian regulating the economic use of cellular resources under limiting conditions and stress emerges as a common perception from numerous recent studies.
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Affiliation(s)
- Benedikt Steuten
- Molecular Biology of Bacteria, Heinrich-Heine-University Düsseldorf, Universitätsstr. 1, D-40225, Düsseldorf, Germany
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Venkataramanan KP, Jones SW, McCormick KP, Kunjeti SG, Ralston MT, Meyers BC, Papoutsakis ET. The Clostridium small RNome that responds to stress: the paradigm and importance of toxic metabolite stress in C. acetobutylicum. BMC Genomics 2013; 14:849. [PMID: 24299206 PMCID: PMC3879012 DOI: 10.1186/1471-2164-14-849] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2013] [Accepted: 11/14/2013] [Indexed: 01/01/2023] Open
Abstract
Background Small non-coding RNAs (sRNA) are emerging as major components of the cell’s regulatory network, several possessing their own regulons. A few sRNAs have been reported as being involved in general or toxic-metabolite stress, mostly in Gram- prokaryotes, but hardly any in Gram+ prokaryotes. Significantly, the role of sRNAs in the stress response remains poorly understood at the genome-scale level. It was previously shown that toxic-metabolite stress is one of the most comprehensive and encompassing stress responses in the cell, engaging both the general stress (or heat-shock protein, HSP) response as well as specialized metabolic programs. Results Using RNA deep sequencing (RNA-seq) we examined the sRNome of C. acetobutylicum in response to the native but toxic metabolites, butanol and butyrate. 7.5% of the RNA-seq reads mapped to genome outside annotated ORFs, thus demonstrating the richness and importance of the small RNome. We used comparative expression analysis of 113 sRNAs we had previously computationally predicted, and of annotated mRNAs to set metrics for reliably identifying sRNAs from RNA-seq data, thus discovering 46 additional sRNAs. Under metabolite stress, these 159 sRNAs displayed distinct expression patterns, a select number of which was verified by Northern analysis. We identified stress-related expression of sRNAs affecting transcriptional (6S, S-box & solB) and translational (tmRNA & SRP-RNA) processes, and 65 likely targets of the RNA chaperone Hfq. Conclusions Our results support an important role for sRNAs for understanding the complexity of the regulatory network that underlies the stress response in Clostridium organisms, whether related to normophysiology, pathogenesis or biotechnological applications.
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Integrated transcriptomic and proteomic analysis of the global response of Wolbachia to doxycycline-induced stress. ISME JOURNAL 2013; 8:925-37. [PMID: 24152719 PMCID: PMC3960535 DOI: 10.1038/ismej.2013.192] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/15/2013] [Revised: 09/12/2013] [Accepted: 09/20/2013] [Indexed: 01/05/2023]
Abstract
The bacterium Wolbachia (order Rickettsiales), representing perhaps the most abundant vertically transmitted microbe worldwide, infects arthropods and filarial nematodes. In arthropods, Wolbachia can induce reproductive alterations and interfere with the transmission of several arthropod-borne pathogens. In addition, Wolbachia is an obligate mutualist of the filarial parasites that cause lymphatic filariasis and onchocerciasis in the tropics. Targeting Wolbachia with tetracycline antibiotics leads to sterilisation and ultimately death of adult filariae. However, several weeks of treatment are required, restricting the implementation of this control strategy. To date, the response of Wolbachia to stress has not been investigated, and almost nothing is known about global regulation of gene expression in this organism. We exposed an arthropod Wolbachia strain to doxycycline in vitro, and analysed differential expression by directional RNA-seq and label-free, quantitative proteomics. We found that Wolbachia responded not only by modulating expression of the translation machinery, but also by upregulating nucleotide synthesis and energy metabolism, while downregulating outer membrane proteins. Moreover, Wolbachia increased the expression of a key component of the twin-arginine translocase (tatA) and a phosphate ABC transporter ATPase (PstB); the latter is associated with decreased susceptibility to antimicrobials in free-living bacteria. Finally, the downregulation of 6S RNA during translational inhibition suggests that this small RNA is involved in growth rate control. Despite its highly reduced genome, Wolbachia shows a surprising ability to regulate gene expression during exposure to a potent stressor. Our findings have general relevance for the chemotherapy of obligate intracellular bacteria and the mechanistic basis of persistence in the Rickettsiales.
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Yan Y, Su S, Meng X, Ji X, Qu Y, Liu Z, Wang X, Cui Y, Deng Z, Zhou D, Jiang W, Yang R, Han Y. Determination of sRNA expressions by RNA-seq in Yersinia pestis grown in vitro and during infection. PLoS One 2013; 8:e74495. [PMID: 24040259 PMCID: PMC3770706 DOI: 10.1371/journal.pone.0074495] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2013] [Accepted: 08/02/2013] [Indexed: 12/21/2022] Open
Abstract
Background Small non-coding RNAs (sRNAs) facilitate host-microbe interactions. They have a central function in the post-transcriptional regulation during pathogenic lifestyles. Hfq, an RNA-binding protein that many sRNAs act in conjunction with, is required for Y. pestis pathogenesis. However, information on how Yersinia pestis modulates the expression of sRNAs during infection is largely unknown. Methodology and Principal Findings We used RNA-seq technology to identify the sRNA candidates expressed from Y. pestis grown invitro and in the infected lungs of mice. A total of 104 sRNAs were found, including 26 previously annotated sRNAs, by searching against the Rfam database with 78 novel sRNA candidates. Approximately 89% (93/104) of these sRNAs from Y. pestis are shared with its ancestor Y. pseudotuberculosis. Ninety-seven percent of these sRNAs (101/104) are shared among more than 80 sequenced genomes of 135 Y. pestis strains. These 78 novel sRNAs include 62 intergenic and 16 antisense sRNAs. Fourteen sRNAs were selected for verification by independent Northern blot analysis. Results showed that nine selected sRNA transcripts were Hfq-dependent. Interestingly, three novel sRNAs were identified as new members of the transcription factor CRP regulon. Semi-quantitative analysis revealed that Y. pestis from the infected lungs induced the expressions of six sRNAs including RyhB1, RyhB2, CyaR/RyeE, 6S RNA, RybB and sR039 and repressed the expressions of four sRNAs, including CsrB, CsrC, 4.5S RNA and sR027. Conclusions and Significance This study is the first attempt to subject RNA from Y. pestis-infected samples to direct high-throughput sequencing. Many novel sRNAs were identified and the expression patterns of relevant sRNAs in Y. pestis during invitro growth and invivo infection were revealed. The annotated sRNAs accounted for the most abundant sRNAs either expressed in bacteria grown invitro or differentially expressed in the infected lungs. These findings suggested these sRNAs may have important functions in Y. pestis physiology or pathogenesis.
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Affiliation(s)
- Yanfeng Yan
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Shanchun Su
- Microbiology Laboratory, Sichuan Agricultural University, Yaan, Sichuan province, China
| | - Xiangrong Meng
- Clinical Laboratory, Huzhong Hispital, Guangzhou, Guangdong province, China
| | - Xiaolan Ji
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Yi Qu
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Zizhong Liu
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Xiaoyi Wang
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Yujun Cui
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Zhongliang Deng
- Department of Sanitary Inspection, School of Public Health, University of South China, Hengyang, Hunan province, China
| | - Dongsheng Zhou
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Wencan Jiang
- Microbiology Laboratory, Sichuan Agricultural University, Yaan, Sichuan province, China
| | - Ruifu Yang
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
- * E-mail: (YH); (RY)
| | - Yanping Han
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
- * E-mail: (YH); (RY)
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46
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Caldelari I, Chao Y, Romby P, Vogel J. RNA-mediated regulation in pathogenic bacteria. Cold Spring Harb Perspect Med 2013; 3:a010298. [PMID: 24003243 DOI: 10.1101/cshperspect.a010298] [Citation(s) in RCA: 130] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Pathogenic bacteria possess intricate regulatory networks that temporally control the production of virulence factors, and enable the bacteria to survive and proliferate after host infection. Regulatory RNAs are now recognized as important components of these networks, and their study may not only identify new approaches to combat infectious diseases but also reveal new general control mechanisms involved in bacterial gene expression. In this review, we illustrate the diversity of regulatory RNAs in bacterial pathogens, their mechanism of action, and how they can be integrated into the regulatory circuits that govern virulence-factor production.
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Affiliation(s)
- Isabelle Caldelari
- Architecture et Réactivité de l'ARN, Université de Strasbourg, CNRS, IBMC, F-67084 Strasbourg, France
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Cabrera-Ostertag IJ, Cavanagh AT, Wassarman KM. Initiating nucleotide identity determines efficiency of RNA synthesis from 6S RNA templates in Bacillus subtilis but not Escherichia coli. Nucleic Acids Res 2013; 41:7501-11. [PMID: 23761441 PMCID: PMC3753640 DOI: 10.1093/nar/gkt517] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The 6S RNA is a non-coding small RNA that binds within the active site of housekeeping forms of RNA polymerases (e.g. Eσ70 in Escherichia coli, EσA in Bacillus subtilis) and regulates transcription. Efficient release of RNA polymerase from 6S RNA regulation during outgrowth from stationary phase is dependent on use of 6S RNA as a template to generate a product RNA (pRNA). Interestingly, B. subtilis has two 6S RNAs, 6S-1 and 6S-2, but only 6S-1 RNA appears to be used efficiently as a template for pRNA synthesis during outgrowth. Here, we demonstrate that the identity of the initiating nucleotide is particularly important for the B. subtilis RNA polymerase to use RNA templates. Specifically, initiation with guanosine triphosphate (GTP) is required for efficient pRNA synthesis, providing mechanistic insight into why 6S-2 RNA does not support robust pRNA synthesis as it initiates with adenosine triphosphate (ATP). Intriguingly, E. coli RNA polymerase does not have a strong preference for initiating nucleotide identity. These observations highlight an important difference in biochemical properties of B. subtilis and E. coli RNA polymerases, specifically in their ability to use RNA templates efficiently, which also may reflect the differences in GTP and ATP metabolism in these two organisms.
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48
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Trigui H, Dudyk P, Sum J, Shuman HA, Faucher SP. Analysis of the transcriptome of Legionella pneumophila hfq mutant reveals a new mobile genetic element. MICROBIOLOGY-SGM 2013; 159:1649-1660. [PMID: 23728622 DOI: 10.1099/mic.0.067983-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Hfq is a small RNA-binding protein involved in the post-transcriptional regulation of gene expression by affecting the stability of the mRNA and by mediating efficient pairing between small regulatory RNAs and their target mRNAs. In Legionella pneumophila, the aetiological agent of Legionnaires' disease, mutation of hfq results in increased duration of the lag phase and reduced growth in low-iron medium. In an effort to uncover genes potentially regulated by Hfq, the transcriptome of an hfq mutant strain was compared to that of the wild-type. Unexpectedly, many genes located within a 100 kb genomic island, including a section of the previously identified efflux island, were overexpressed in the hfq mutant strain. Since this island contains a putative conjugative system and an integrase, it was postulated that it could be a new integrated mobile genetic element. PCR analysis revealed that this region exists both as an integrated and as an episomal form in the cell population and that it undergoes differential excision in the hfq mutant background, which was further confirmed by trans-complementation of the hfq mutation. This new plasmid-like element was named pLP100. Differential excision did not affect the copy number of pLP100 at the population level. This region contains a copper efflux pump encoded by copA, and increased resistance to copper was observed for the hfq mutant strain that was abrogated in the complemented strain. A strain carrying a mutation of hfq and a deletion of the right side recombination site, attR, showed that overexpression of pLP100 genes and increased copper resistance in the hfq mutant strain were dependent upon excision of pLP100.
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Affiliation(s)
- Hana Trigui
- Department of Natural Resource Sciences, Faculty of Agricultural and Environmental Sciences, McGill University, Ste-Anne-de-Bellevue, QC, Canada
| | - Paulina Dudyk
- Department of Natural Resource Sciences, Faculty of Agricultural and Environmental Sciences, McGill University, Ste-Anne-de-Bellevue, QC, Canada
| | - Janet Sum
- Department of Microbiology and Immunology, Columbia University Medical Center, New York, NY, USA
| | - Howard A Shuman
- Department of Microbiology and Immunology, Columbia University Medical Center, New York, NY, USA
| | - Sebastien P Faucher
- Department of Natural Resource Sciences, Faculty of Agricultural and Environmental Sciences, McGill University, Ste-Anne-de-Bellevue, QC, Canada
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de Barsy M, Greub G. Functional genomics of intracellular bacteria. Brief Funct Genomics 2013; 12:341-53. [DOI: 10.1093/bfgp/elt012] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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50
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Jiménez-Zurdo JI, Valverde C, Becker A. Insights into the noncoding RNome of nitrogen-fixing endosymbiotic α-proteobacteria. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2013; 26:160-167. [PMID: 22991999 DOI: 10.1094/mpmi-07-12-0186-cr] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Symbiotic chronic infection of legumes by rhizobia involves transition of invading bacteria from a free-living environment in soil to an intracellular state as differentiated nitrogen-fixing bacteroids within the nodules elicited in the host plant. The adaptive flexibility demanded by this complex lifestyle is likely facilitated by the large set of regulatory proteins encoded by rhizobial genomes. However, proteins are not the only relevant players in the regulation of gene expression in bacteria. Large-scale high-throughput analysis of prokaryotic genomes is evidencing the expression of an unexpected plethora of small untranslated transcripts (sRNAs) with housekeeping or regulatory roles. sRNAs mostly act in response to environmental cues as post-transcriptional regulators of gene expression through protein-assisted base-pairing interactions with target mRNAs. Riboregulation contributes to fine-tune a wide range of bacterial processes which, in intracellular animal pathogens, largely compromise virulence traits. Here, we summarize the incipient knowledge about the noncoding RNome structure of nitrogen-fixing endosymbiotic bacteria as inferred from genome-wide searches for sRNA genes in the alfalfa partner Sinorhizobium meliloti and further comparative genomics analysis. The biology of relevant S. meliloti RNA chaperones (e.g., Hfq) is also reviewed as a first global indicator of the impact of riboregulation in the establishment of the symbiotic interaction.
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Affiliation(s)
- José I Jiménez-Zurdo
- Grupo de Ecología Genética de la Rizosfera, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas (CSIC), 18008 Granada, Spain.
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