1
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Lv F, Zhan Y, Feng H, Sun W, Yin C, Han Y, Shao Y, Xue W, Jiang S, Ma Y, Hu H, Wei J, Yan Y, Lin M. Integrated Hfq-interacting RNAome and transcriptomic analysis reveals complex regulatory networks of nitrogen fixation in root-associated Pseudomonas stutzeri A1501. mSphere 2024; 9:e0076223. [PMID: 38747590 PMCID: PMC11332353 DOI: 10.1128/msphere.00762-23] [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] [Received: 12/17/2023] [Accepted: 04/10/2024] [Indexed: 06/26/2024] Open
Abstract
The RNA chaperone Hfq acts as a global regulator of numerous biological processes, such as carbon/nitrogen metabolism and environmental adaptation in plant-associated diazotrophs; however, its target RNAs and the mechanisms underlying nitrogen fixation remain largely unknown. Here, we used enhanced UV cross-linking immunoprecipitation coupled with high-throughput sequencing to identify hundreds of Hfq-binding RNAs probably involved in nitrogen fixation, carbon substrate utilization, biofilm formation, and other functions. Collectively, these processes endow strain A1501 with the requisite capabilities to thrive in the highly competitive rhizosphere. Our findings revealed a previously uncharted landscape of Hfq target genes. Notable among these is nifM, encoding an isomerase necessary for nitrogenase reductase solubility; amtB, encoding an ammonium transporter; oprB, encoding a carbohydrate porin; and cheZ, encoding a chemotaxis protein. Furthermore, we identified more than 100 genes of unknown function, which expands the potential direct regulatory targets of Hfq in diazotrophs. Our data showed that Hfq directly interacts with the mRNA of regulatory proteins (RsmA, AlgU, and NifA), regulatory ncRNA RsmY, and other potential targets, thus revealing the mechanistic links in nitrogen fixation and other metabolic pathways. IMPORTANCE Numerous experimental approaches often face challenges in distinguishing between direct and indirect effects of Hfq-mediated regulation. New technologies based on high-throughput sequencing are increasingly providing insight into the global regulation of Hfq in gene expression. Here, enhanced UV cross-linking immunoprecipitation coupled with high-throughput sequencing was employed to identify the Hfq-binding sites and potential targets in the root-associated Pseudomonas stutzeri A1501 and identify hundreds of novel Hfq-binding RNAs that are predicted to be involved in metabolism, environmental adaptation, and nitrogen fixation. In particular, we have shown Hfq interactions with various regulatory proteins' mRNA and their potential targets at the posttranscriptional level. This study not only enhances our understanding of Hfq regulation but, importantly, also provides a framework for addressing integrated regulatory network underlying root-associated nitrogen fixation.
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Affiliation(s)
- Fanyang Lv
- Biotechnology Research Institute/National Key Laboratory of Agricultural Microbiology, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Yuhua Zhan
- Biotechnology Research Institute/National Key Laboratory of Agricultural Microbiology, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Haichao Feng
- College of Agriculture, Henan University, Kaifeng, Henan, China
| | - Wenyue Sun
- Biotechnology Research Institute/National Key Laboratory of Agricultural Microbiology, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Changyan Yin
- Biotechnology Research Institute/National Key Laboratory of Agricultural Microbiology, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Yueyue Han
- Biotechnology Research Institute/National Key Laboratory of Agricultural Microbiology, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Yahui Shao
- Biotechnology Research Institute/National Key Laboratory of Agricultural Microbiology, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Wei Xue
- Biotechnology Research Institute/National Key Laboratory of Agricultural Microbiology, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Shanshan Jiang
- Biotechnology Research Institute/National Key Laboratory of Agricultural Microbiology, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Yiyuan Ma
- Biotechnology Research Institute/National Key Laboratory of Agricultural Microbiology, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Haonan Hu
- Biotechnology Research Institute/National Key Laboratory of Agricultural Microbiology, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Jinfeng Wei
- College of Agriculture, Henan University, Kaifeng, Henan, China
| | - Yongliang Yan
- Biotechnology Research Institute/National Key Laboratory of Agricultural Microbiology, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Min Lin
- College of Agriculture, Henan University, Kaifeng, Henan, China
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2
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Jung YJ, Park KH, Jang TY, Yoo SM. Gene expression regulation by modulating Hfq expression in coordination with tailor-made sRNA-based knockdown in Escherichia coli. J Biotechnol 2024; 388:1-10. [PMID: 38616040 DOI: 10.1016/j.jbiotec.2024.04.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2024] [Revised: 04/04/2024] [Accepted: 04/11/2024] [Indexed: 04/16/2024]
Abstract
The tailor-made synthetic sRNA-based gene expression knockdown system has demonstrated its efficacy in achieving pathway balancing in microbes, facilitating precise target gene repression and fine-tuned control of gene expression. This system operates under a competitive mode of gene regulation, wherein the tailor-made synthetic sRNA shares the intrinsic intracellular Hfq protein with other RNAs. The limited intracellular Hfq amount has the potential to become a constraining factor in the post-transcription regulation of sRNAs. To enhance the efficiency of the tailor-made sRNA gene expression regulation platform, we introduced an Hfq expression level modulation-coordinated sRNA-based gene knockdown system. This system comprises tailor-made sRNA expression cassettes that produce varying Hfq expression levels using different strength promoters. Modulating the expression levels of Hfq significantly improved the repressing capacity of sRNA, as evidenced by evaluations with four fluorescence proteins. In order to validate the practical application of this system, we applied the Hfq-modulated sRNA-based gene knockdown cassette to Escherichia coli strains producing 5-aminolevulinic acid and L-tyrosine. Diversifying the expression levels of metabolic enzymes through this cassette resulted in substantial increases of 74.6% in 5-aminolevulinic acid and 144% in L-tyrosine production. Tailor-made synthetic sRNA-based gene expression knockdown system, coupled with Hfq copy modulation, exhibits potential for optimizing metabolic fluxes through biosynthetic pathways, thereby enhancing the production yields of bioproducts.
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Affiliation(s)
- Yu Jung Jung
- School of Integrative Engineering, Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul 06974, Republic of Korea
| | - Keun Ha Park
- School of Integrative Engineering, Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul 06974, Republic of Korea
| | - Tae Yeong Jang
- School of Integrative Engineering, Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul 06974, Republic of Korea
| | - Seung Min Yoo
- School of Integrative Engineering, Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul 06974, Republic of Korea.
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3
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Lorenzetti APR, Kusebauch U, Zaramela LS, Wu WJ, de Almeida JPP, Turkarslan S, L. G. de Lomana A, Gomes-Filho JV, Vêncio RZN, Moritz RL, Koide T, Baliga NS. A Genome-Scale Atlas Reveals Complex Interplay of Transcription and Translation in an Archaeon. mSystems 2023; 8:e0081622. [PMID: 36912639 PMCID: PMC10134880 DOI: 10.1128/msystems.00816-22] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2022] [Accepted: 02/10/2023] [Indexed: 03/14/2023] Open
Abstract
The scale of post-transcriptional regulation and the implications of its interplay with other forms of regulation in environmental acclimation are underexplored for organisms of the domain Archaea. Here, we have investigated the scale of post-transcriptional regulation in the extremely halophilic archaeon Halobacterium salinarum NRC-1 by integrating the transcriptome-wide locations of transcript processing sites (TPSs) and SmAP1 binding, the genome-wide locations of antisense RNAs (asRNAs), and the consequences of RNase_2099C knockout on the differential expression of all genes. This integrated analysis has discovered that 54% of all protein-coding genes in the genome of this haloarchaeon are likely targeted by multiple mechanisms for putative post-transcriptional processing and regulation, with about 20% of genes likely being regulated by combinatorial schemes involving SmAP1, asRNAs, and RNase_2099C. Comparative analysis of mRNA levels (transcriptome sequencing [RNA-Seq]) and protein levels (sequential window acquisition of all theoretical fragment ion spectra mass spectrometry [SWATH-MS]) for 2,579 genes over four phases of batch culture growth in complex medium generated additional evidence for the conditional post-transcriptional regulation of 7% of all protein-coding genes. We demonstrate that post-transcriptional regulation may act to fine-tune specialized and rapid acclimation to stressful environments, e.g., as a switch to turn on gas vesicle biogenesis to promote vertical relocation under anoxic conditions and modulate the frequency of transposition by insertion sequence (IS) elements of the IS200/IS605, IS4, and ISH3 families. Findings from this study are provided as an atlas in a public Web resource (https://halodata.systemsbiology.net). IMPORTANCE While the transcriptional regulation landscape of archaea has been extensively investigated, we currently have limited knowledge about post-transcriptional regulation and its driving mechanisms in this domain of life. In this study, we collected and integrated omics data from multiple sources and technologies to infer post-transcriptionally regulated genes and the putative mechanisms modulating their expression at the protein level in Halobacterium salinarum NRC-1. The results suggest that post-transcriptional regulation may drive environmental acclimation by regulating hallmark biological processes. To foster discoveries by other research groups interested in the topic, we extended our integrated data to the public in the form of an interactive atlas (https://halodata.systemsbiology.net).
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Affiliation(s)
- Alan P. R. Lorenzetti
- Department of Biochemistry and Immunology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, Brazil
- Institute for Systems Biology, Seattle, Washington, USA
| | | | - Lívia S. Zaramela
- Department of Biochemistry and Immunology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, Brazil
| | - Wei-Ju Wu
- Institute for Systems Biology, Seattle, Washington, USA
| | - João P. P. de Almeida
- Department of Biochemistry and Immunology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, Brazil
| | | | | | - José V. Gomes-Filho
- Department of Biochemistry and Immunology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, Brazil
| | - Ricardo Z. N. Vêncio
- Department of Computation and Mathematics, Faculty of Philosophy, Sciences and Letters at Ribeirão Preto, University of São Paulo, Ribeirão Preto, Brazil
| | | | - Tie Koide
- Department of Biochemistry and Immunology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, Brazil
| | - Nitin S. Baliga
- Institute for Systems Biology, Seattle, Washington, USA
- Department of Biology, University of Washington, Seattle, Washington, USA
- Department of Microbiology, University of Washington, Seattle, Washington, USA
- Molecular and Cellular Biology Program, University of Washington, Seattle, Washington, USA
- Lawrence Berkeley National Lab, Berkeley, California, USA
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4
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Synthetic Genetic Interactions Reveal a Dense and Cryptic Regulatory Network of Small Noncoding RNAs in Escherichia coli. mBio 2022; 13:e0122522. [PMID: 35920556 PMCID: PMC9426594 DOI: 10.1128/mbio.01225-22] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022] Open
Abstract
Over the past 20 years, we have learned that bacterial small noncoding RNAs (sRNAs) can rapidly effect changes in gene expression in response to stress. However, the broader role and impact of sRNA-mediated regulation in promoting bacterial survival has remained elusive. Indeed, there are few examples where disruption of sRNA-mediated gene regulation results in a discernible change in bacterial growth or survival. The lack of phenotypes attributable to loss of sRNA function suggests that either sRNAs are wholly dispensable or functional redundancies mask the impact of deleting a single sRNA. We investigated synthetic genetic interactions among sRNA genes in Escherichia coli by constructing pairwise deletions in 54 genes, including 52 sRNAs. Some 1,373 double deletion strains were studied for growth defects under 32 different nutrient stress conditions and revealed 1,131 genetic interactions. In one example, we identified a profound synthetic lethal interaction between ArcZ and CsrC when E. coli was grown on pyruvate, lactate, oxaloacetate, or d-/l-alanine, and we provide evidence that the expression of ppsA is dysregulated in the double deletion background, causing the conditionally lethal phenotype. This work employs a unique platform for studying sRNA-mediated gene regulation and sheds new light on the genetic network of sRNAs that underpins bacterial growth.
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5
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Katsuya-Gaviria K, Paris G, Dendooven T, Bandyra KJ. Bacterial RNA chaperones and chaperone-like riboregulators: behind the scenes of RNA-mediated regulation of cellular metabolism. RNA Biol 2021; 19:419-436. [PMID: 35438047 PMCID: PMC9037510 DOI: 10.1080/15476286.2022.2048565] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Accepted: 02/26/2022] [Indexed: 11/02/2022] Open
Abstract
In all domains of life, RNA chaperones safeguard and guide the fate of the cellular RNA pool. RNA chaperones comprise structurally diverse proteins that ensure proper folding, stability, and ribonuclease resistance of RNA, and they support regulatory activities mediated by RNA. RNA chaperones constitute a topologically diverse group of proteins that often present an unstructured region and bind RNA with limited nucleotide sequence preferences. In bacteria, three main proteins - Hfq, ProQ, and CsrA - have been shown to regulate numerous complex processes, including bacterial growth, stress response and virulence. Hfq and ProQ have well-studied activities as global chaperones with pleiotropic impact, while CsrA has a chaperone-like role with more defined riboregulatory function. Here, we describe relevant novel insights into their common features, including RNA binding properties, unstructured domains, and interplay with other proteins important to RNA metabolism.
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Affiliation(s)
- Kai Katsuya-Gaviria
- Department of Biochemistry, University of Cambridge, Tennis Court Road, CambridgeCB2 1GA, UK
| | - Giulia Paris
- Department of Biochemistry, University of Cambridge, Tennis Court Road, CambridgeCB2 1GA, UK
| | - Tom Dendooven
- Department of Structural Studies, MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, UK
| | - Katarzyna J. Bandyra
- Biological and Chemical Research Centre, Department of Chemistry, University of Warsaw, 02-089Warsaw, Poland
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6
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Sudo N, Lee K, Sekine Y, Ohnishi M, Iyoda S. RNA-binding protein Hfq downregulates locus of enterocyte effacement-encoded regulators independent of small regulatory RNA in enterohemorrhagic Escherichia coli. Mol Microbiol 2021; 117:86-101. [PMID: 34411346 DOI: 10.1111/mmi.14799] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Revised: 08/16/2021] [Accepted: 08/16/2021] [Indexed: 11/25/2022]
Abstract
Enterohemorrhagic Escherichia coli (EHEC) causes severe human diseases worldwide. The type 3 secretion system and effector proteins are essential for EHEC infection, and are encoded by the locus of enterocyte effacement (LEE). RNA-binding protein Hfq is essential for small regulatory RNA (sRNA)-mediated regulation at a posttranscriptional level and full virulence of many pathogenic bacteria. Although two early studies indicated that Hfq represses LEE expression by posttranscriptionally controlling the expression of genes grlRA and/or ler, both of which encode LEE regulators mediating a positive regulatory loop, the detailed molecular mechanism and biological significance remain unclear. Herein, we show that LEE overexpression was caused by defective RNA-binding activity of the Hfq distal face, which posttranscriptionally represses grlA and ler expression. In vitro analyses revealed that the Hfq distal face directly binds near the translational initiation site of grlA and ler mRNAs, and inhibits their translation. Taken together, we conclude that Hfq inhibits grlA and ler translation by binding their mRNAs through the distal face in an sRNA-independent manner. Additionally, we show that Hfq-mediated repression of LEE is critical for normal EHEC growth because all suppressor mutations that restored the growth defect in the hfq mutant abolished hfq deletion-induced overexpression of LEE.
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Affiliation(s)
- Naoki Sudo
- Department of Bacteriology I, National Institute of Infectious Diseases, Tokyo, Japan
| | - Kenichi Lee
- Department of Bacteriology I, National Institute of Infectious Diseases, Tokyo, Japan
| | - Yasuhiko Sekine
- Department of Life Science, College of Science, Rikkyo University, Tokyo, Japan
| | - Makoto Ohnishi
- Department of Bacteriology I, National Institute of Infectious Diseases, Tokyo, Japan
| | - Sunao Iyoda
- Department of Bacteriology I, National Institute of Infectious Diseases, Tokyo, Japan
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7
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Fu Y, Yu Z, Zhu L, Li Z, Yin W, Shang X, Chou SH, Tan Q, He J. The Multiple Regulatory Relationship Between RNA-Chaperone Hfq and the Second Messenger c-di-GMP. Front Microbiol 2021; 12:689619. [PMID: 34335515 PMCID: PMC8323549 DOI: 10.3389/fmicb.2021.689619] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Accepted: 06/18/2021] [Indexed: 11/25/2022] Open
Abstract
RNA chaperone protein Hfq is an important post-transcriptional regulator in bacteria, while c-di-GMP is a second messenger signaling molecule widely distributed in bacteria. Both factors have been found to play key roles in post-transcriptional regulation and signal transduction pathways, respectively. Intriguingly, the two factors show some common aspects in the regulation of certain physiological functions such as bacterial motility, biofilm formation, pathogenicity and so on. Therefore, there may be regulatory relationship between Hfq and c-di-GMP. For example, Hfq can directly regulate the activity of c-di-GMP metabolic enzymes or alter the c-di-GMP level through other systems, while c-di-GMP can indirectly enhance or inhibit the hfq gene expression through intermediate factors. In this article, after briefly introducing the Hfq and c-di-GMP regulatory systems, we will focus on the direct and indirect regulation reported between Hfq and c-di-GMP, aiming to compare and link the two regulatory systems to further study the complicated physiological and metabolic systems of bacteria, and to lay a solid foundation for drawing a more complete global regulatory network.
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Affiliation(s)
- Yang Fu
- National Engineering Research Center of Edible Fungi, Institute of Edible Fungi, Shanghai Academy of Agricultural Sciences, Shanghai, China.,State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Zhaoqing Yu
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Li Zhu
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Zhou Li
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Wen Yin
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Xiaodong Shang
- National Engineering Research Center of Edible Fungi, Institute of Edible Fungi, Shanghai Academy of Agricultural Sciences, Shanghai, China
| | - Shan-Ho Chou
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Qi Tan
- National Engineering Research Center of Edible Fungi, Institute of Edible Fungi, Shanghai Academy of Agricultural Sciences, Shanghai, China
| | - Jin He
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China
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8
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Krepl M, Dendooven T, Luisi BF, Sponer J. MD simulations reveal the basis for dynamic assembly of Hfq-RNA complexes. J Biol Chem 2021; 296:100656. [PMID: 33857481 PMCID: PMC8121710 DOI: 10.1016/j.jbc.2021.100656] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Revised: 04/06/2021] [Accepted: 04/09/2021] [Indexed: 01/05/2023] Open
Abstract
The conserved protein Hfq is a key factor in the RNA-mediated control of gene expression in most known bacteria. The transient intermediates Hfq forms with RNA support intricate and robust regulatory networks. In Pseudomonas, Hfq recognizes repeats of adenine–purine–any nucleotide (ARN) in target mRNAs via its distal binding side, and together with the catabolite repression control (Crc) protein, assembles into a translation–repression complex. Earlier experiments yielded static, ensemble-averaged structures of the complex, but details of its interface dynamics and assembly pathway remained elusive. Using explicit solvent atomistic molecular dynamics simulations, we modeled the extensive dynamics of the Hfq–RNA interface and found implications for the assembly of the complex. We predict that syn/anti flips of the adenine nucleotides in each ARN repeat contribute to a dynamic recognition mechanism between the Hfq distal side and mRNA targets. We identify a previously unknown binding pocket that can accept any nucleotide and propose that it may serve as a ‘status quo’ staging point, providing nonspecific binding affinity, until Crc engages the Hfq–RNA binary complex. The dynamical components of the Hfq–RNA recognition can speed up screening of the pool of the surrounding RNAs, participate in rapid accommodation of the RNA on the protein surface, and facilitate competition among different RNAs. The register of Crc in the ternary assembly could be defined by the recognition of a guanine-specific base–phosphate interaction between the first and last ARN repeats of the bound RNA. This dynamic substrate recognition provides structural rationale for the stepwise assembly of multicomponent ribonucleoprotein complexes nucleated by Hfq–RNA binding.
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Affiliation(s)
- Miroslav Krepl
- Institute of Biophysics of the Czech Academy of Sciences, Brno, Czech Republic.
| | - Tom Dendooven
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom; MRC-LMB, Cambridge, United Kingdom
| | - Ben F Luisi
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
| | - Jiri Sponer
- Institute of Biophysics of the Czech Academy of Sciences, Brno, Czech Republic
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9
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Gerovac M, Vogel J, Smirnov A. The World of Stable Ribonucleoproteins and Its Mapping With Grad-Seq and Related Approaches. Front Mol Biosci 2021; 8:661448. [PMID: 33898526 PMCID: PMC8058203 DOI: 10.3389/fmolb.2021.661448] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2021] [Accepted: 03/04/2021] [Indexed: 12/13/2022] Open
Abstract
Macromolecular complexes of proteins and RNAs are essential building blocks of cells. These stable supramolecular particles can be viewed as minimal biochemical units whose structural organization, i.e., the way the RNA and the protein interact with each other, is directly linked to their biological function. Whether those are dynamic regulatory ribonucleoproteins (RNPs) or integrated molecular machines involved in gene expression, the comprehensive knowledge of these units is critical to our understanding of key molecular mechanisms and cell physiology phenomena. Such is the goal of diverse complexomic approaches and in particular of the recently developed gradient profiling by sequencing (Grad-seq). By separating cellular protein and RNA complexes on a density gradient and quantifying their distributions genome-wide by mass spectrometry and deep sequencing, Grad-seq charts global landscapes of native macromolecular assemblies. In this review, we propose a function-based ontology of stable RNPs and discuss how Grad-seq and related approaches transformed our perspective of bacterial and eukaryotic ribonucleoproteins by guiding the discovery of new RNA-binding proteins and unusual classes of noncoding RNAs. We highlight some methodological aspects and developments that permit to further boost the power of this technique and to look for exciting new biology in understudied and challenging biological models.
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Affiliation(s)
- Milan Gerovac
- Institute of Molecular Infection Biology (IMIB), University of Würzburg, Würzburg, Germany
| | - Jörg Vogel
- Institute of Molecular Infection Biology (IMIB), University of Würzburg, Würzburg, Germany
- Helmholtz Institute for RNA-based Infection Research (HIRI), Helmholtz Centre for Infection Research (HZI), Würzburg, Germany
| | - Alexandre Smirnov
- UMR 7156—Génétique Moléculaire, Génomique, Microbiologie (GMGM), University of Strasbourg, CNRS, Strasbourg, France
- University of Strasbourg Institute for Advanced Study (USIAS), Strasbourg, France
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10
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Irastortza-Olaziregi M, Amster-Choder O. Coupled Transcription-Translation in Prokaryotes: An Old Couple With New Surprises. Front Microbiol 2021; 11:624830. [PMID: 33552035 PMCID: PMC7858274 DOI: 10.3389/fmicb.2020.624830] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2020] [Accepted: 12/18/2020] [Indexed: 01/17/2023] Open
Abstract
Coupled transcription-translation (CTT) is a hallmark of prokaryotic gene expression. CTT occurs when ribosomes associate with and initiate translation of mRNAs whose transcription has not yet concluded, therefore forming "RNAP.mRNA.ribosome" complexes. CTT is a well-documented phenomenon that is involved in important gene regulation processes, such as attenuation and operon polarity. Despite the progress in our understanding of the cellular signals that coordinate CTT, certain aspects of its molecular architecture remain controversial. Additionally, new information on the spatial segregation between the transcriptional and the translational machineries in certain species, and on the capability of certain mRNAs to localize translation-independently, questions the unanimous occurrence of CTT. Furthermore, studies where transcription and translation were artificially uncoupled showed that transcription elongation can proceed in a translation-independent manner. Here, we review studies supporting the occurrence of CTT and findings questioning its extent, as well as discuss mechanisms that may explain both coupling and uncoupling, e.g., chromosome relocation and the involvement of cis- or trans-acting elements, such as small RNAs and RNA-binding proteins. These mechanisms impact RNA localization, stability, and translation. Understanding the two options by which genes can be expressed and their consequences should shed light on a new layer of control of bacterial transcripts fate.
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Affiliation(s)
- Mikel Irastortza-Olaziregi
- Department of Microbiology and Molecular Genetics, Faculty of Medicine, IMRIC, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Orna Amster-Choder
- Department of Microbiology and Molecular Genetics, Faculty of Medicine, IMRIC, The Hebrew University of Jerusalem, Jerusalem, Israel
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11
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Orans J, Kovach AR, Hoff KE, Horstmann NM, Brennan RG. Crystal structure of an Escherichia coli Hfq Core (residues 2-69)-DNA complex reveals multifunctional nucleic acid binding sites. Nucleic Acids Res 2020; 48:3987-3997. [PMID: 32133526 PMCID: PMC7144919 DOI: 10.1093/nar/gkaa149] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Accepted: 02/26/2020] [Indexed: 12/13/2022] Open
Abstract
Hfq regulates bacterial gene expression post-transcriptionally by binding small RNAs and their target mRNAs, facilitating sRNA-mRNA annealing, typically resulting in translation inhibition and RNA turnover. Hfq is also found in the nucleoid and binds double-stranded (ds) DNA with a slight preference for A-tracts. Here, we present the crystal structure of the Escherichia coli Hfq Core bound to a 30 bp DNA, containing three 6 bp A-tracts. Although previously postulated to bind to the ‘distal’ face, three statistically disordered double stranded DNA molecules bind across the proximal face of the Hfq hexamer as parallel, straight rods with B-DNA like conformational properties. One DNA duplex spans the diameter of the hexamer and passes over the uridine-binding proximal-face pore, whereas the remaining DNA duplexes interact with the rims and serve as bridges between adjacent hexamers. Binding is sequence-independent with residues N13, R16, R17 and Q41 interacting exclusively with the DNA backbone. Atomic force microscopy data support the sequence-independent nature of the Hfq-DNA interaction and a role for Hfq in DNA compaction and nucleoid architecture. Our structure and nucleic acid-binding studies also provide insight into the mechanism of sequence-independent binding of Hfq to dsRNA stems, a function that is critical for proper riboregulation.
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Affiliation(s)
- Jillian Orans
- Department of Biochemistry, Duke University School of Medicine, Durham, NC 27710, USA
| | - Alexander R Kovach
- Department of Biochemistry, Duke University School of Medicine, Durham, NC 27710, USA
| | - Kirsten E Hoff
- Department of Biochemistry, Duke University School of Medicine, Durham, NC 27710, USA
| | - Nicola M Horstmann
- Department of Infectious Diseases, Infection Control Research, University of Texas MD Anderson Cancer Center, Houston TX 77054, USA
| | - Richard G Brennan
- Department of Biochemistry, Duke University School of Medicine, Durham, NC 27710, USA
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12
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Widespread targeting of nascent transcripts by RsmA in Pseudomonas aeruginosa. Proc Natl Acad Sci U S A 2020; 117:10520-10529. [PMID: 32332166 DOI: 10.1073/pnas.1917587117] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
In the opportunistic pathogen Pseudomonas aeruginosa, RsmA is an RNA-binding protein that plays critical roles in the control of virulence, interbacterial interactions, and biofilm formation. Although RsmA is thought to exert its regulatory effects by binding full-length transcripts, the extent to which RsmA binds nascent transcripts has not been addressed. Moreover, which transcripts are direct targets of this key posttranscriptional regulator is largely unknown. Using chromatin immunoprecipitation coupled with high-throughput DNA sequencing, with cells grown in the presence and absence of the RNA polymerase inhibitor rifampicin, we identify hundreds of nascent transcripts that RsmA associates with in P. aeruginosa We also find that the RNA chaperone Hfq targets a subset of those nascent transcripts that RsmA associates with and that the two RNA-binding proteins can exert regulatory effects on common targets. Our findings establish that RsmA associates with many transcripts as they are being synthesized in P. aeruginosa, identify the transcripts targeted by RsmA, and suggest that RsmA and Hfq may act in a combinatorial fashion on certain transcripts. The binding of posttranscriptional regulators to nascent transcripts may be commonplace in bacteria where distinct regulators can function alone or in concert to achieve control over the translation of transcripts as soon as they emerge from RNA polymerase.
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13
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Dos Santos RF, Arraiano CM, Andrade JM. New molecular interactions broaden the functions of the RNA chaperone Hfq. Curr Genet 2019; 65:1313-1319. [PMID: 31104083 DOI: 10.1007/s00294-019-00990-y] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Revised: 05/03/2019] [Accepted: 05/06/2019] [Indexed: 01/09/2023]
Abstract
The RNA chaperone Hfq is an important bacterial post-transcriptional regulator. Most studies on Hfq are focused on the role of this protein on small non-coding RNAs (sRNAs) and messenger RNAs (mRNAs). The most well-characterized function of Hfq is its role as RNA matchmaker, promoting the base-pairing between sRNAs and their mRNA targets. However, novel substrates and previous unrecognized functions of Hfq have now been identified, which expanded the regulatory spectrum of this protein. Hfq was recently found to bind rRNA and act as a new ribosome biogenesis factor, affecting rRNA processing, ribosome assembly, translational efficiency and translational fidelity. Hfq was also found to bind tRNAs, which could provide an additional mechanism for its role on the accuracy of protein synthesis. The list of substrates does not include RNA exclusively since Hfq was shown to bind DNA, playing an important role in DNA compaction. Additionally, Hfq is also capable to establish many protein-protein interactions. Overall, the functions of the RNA-binding protein Hfq have been expanded beyond its function in small RNA-mediated regulation. The identification of additional substrates and new functions provides alternative explanations for the importance of the chaperone Hfq as a global regulator.
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Affiliation(s)
- Ricardo F Dos Santos
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Avenida da República, 2780-157, Oeiras, Portugal
| | - Cecília M Arraiano
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Avenida da República, 2780-157, Oeiras, Portugal.
| | - José M Andrade
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Avenida da República, 2780-157, Oeiras, Portugal.
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14
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Pei XY, Dendooven T, Sonnleitner E, Chen S, Bläsi U, Luisi BF. Architectural principles for Hfq/Crc-mediated regulation of gene expression. eLife 2019; 8:e43158. [PMID: 30758287 PMCID: PMC6422490 DOI: 10.7554/elife.43158] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2018] [Accepted: 02/11/2019] [Indexed: 12/24/2022] Open
Abstract
In diverse bacterial species, the global regulator Hfq contributes to post-transcriptional networks that control expression of numerous genes. Hfq of the opportunistic pathogen Pseudomonas aeruginosa inhibits translation of target transcripts by forming a regulatory complex with the catabolite repression protein Crc. This repressive complex acts as part of an intricate mechanism of preferred nutrient utilisation. We describe high-resolution cryo-EM structures of the assembly of Hfq and Crc bound to the translation initiation site of a target mRNA. The core of the assembly is formed through interactions of two cognate RNAs, two Hfq hexamers and a Crc pair. Additional Crc protomers are recruited to the core to generate higher-order assemblies with demonstrated regulatory activity in vivo. This study reveals how Hfq cooperates with a partner protein to regulate translation, and provides a structural basis for an RNA code that guides global regulators to interact cooperatively and regulate different RNA targets.
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Affiliation(s)
- Xue Yuan Pei
- Department of BiochemistryUniversity of CambridgeCambridgeUnited Kingdom
| | - Tom Dendooven
- Department of BiochemistryUniversity of CambridgeCambridgeUnited Kingdom
| | - Elisabeth Sonnleitner
- Department of Microbiology, Immunobiology and Genetics, Max F Perutz Laboratories, Center of Molecular BiologyUniversity of Vienna, Vienna BiocenterViennaAustria
| | - Shaoxia Chen
- MRC Laboratory of Molecular BiologyCambridgeUnited Kingdom
| | - Udo Bläsi
- Department of Microbiology, Immunobiology and Genetics, Max F Perutz Laboratories, Center of Molecular BiologyUniversity of Vienna, Vienna BiocenterViennaAustria
| | - Ben F Luisi
- Department of BiochemistryUniversity of CambridgeCambridgeUnited Kingdom
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15
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Morita T, Aiba H. Mechanism and physiological significance of autoregulation of the Escherichia coli hfq gene. RNA (NEW YORK, N.Y.) 2019; 25:264-276. [PMID: 30487269 PMCID: PMC6348989 DOI: 10.1261/rna.068106.118] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Accepted: 11/23/2018] [Indexed: 06/09/2023]
Abstract
The RNA chaperone Hfq plays a critical role in sRNA-mediated gene regulation in enteric bacteria. The major role of Hfq is to stimulate base-pairing between sRNAs and target mRNAs by binding both RNAs through three RNA-binding surfaces. To understand the post-transcriptional network exerted by Hfq and its associated sRNAs, it is important to know how the cellular concentration of Hfq is regulated. While an early study showed that hfq translation is repressed by Hfq, the detailed mechanism and biological significance of the hfq autoregulation remain to be studied. Here, we show that the synthesis of Hfq is strictly autoregulated to maintain the cellular concentration of Hfq within a limited range even when the hfq mRNA is overexpressed from a plasmid-borne hfq gene. Mutational and biochemical studies demonstrate that Hfq represses its own translation primarily by binding to the hfq mRNA through the distal face. The growth of cells harboring the hfq plasmid is markedly inhibited due to an increased Hfq level when the distal face of Hfq is mutated or the 5'-UTR of hfq is mutated. A mutation in the rim suppresses the growth inhibition caused by the distal face mutation, suggesting that the interaction of Hfq with undefined RNAs through the rim is responsible for the growth inhibition by the increased Hfq level. In addition, the data suggest that the hfq autoregulation operates not only in cells harboring a multicopy hfq gene but also in the wild-type cells.
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Affiliation(s)
- Teppei Morita
- Faculty of Pharmaceutical Sciences, Suzuka University of Medical Sciences, Suzuka, Mie, 513-8670, Japan
| | - Hiroji Aiba
- Faculty of Pharmaceutical Sciences, Suzuka University of Medical Sciences, Suzuka, Mie, 513-8670, Japan
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16
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Abstract
RNA-binding proteins chaperone the biological functions of noncoding RNA by reducing RNA misfolding, improving matchmaking between regulatory RNA and targets, and exerting quality control over RNP biogenesis. Recent studies of Escherichia coli CspA, HIV NCp, and E. coli Hfq are beginning to show how RNA-binding proteins remodel RNA structures. These different protein families use common strategies for disrupting or annealing RNA double helices, which can be used to understand the mechanisms by which proteins chaperone RNA-dependent regulation in bacteria.
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17
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Kambara TK, Ramsey KM, Dove SL. Pervasive Targeting of Nascent Transcripts by Hfq. Cell Rep 2018; 23:1543-1552. [PMID: 29719264 PMCID: PMC5990048 DOI: 10.1016/j.celrep.2018.03.134] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Revised: 03/02/2018] [Accepted: 03/29/2018] [Indexed: 12/18/2022] Open
Abstract
Hfq is an RNA chaperone and an important post-transcriptional regulator in bacteria. Using chromatin immunoprecipitation coupled with high-throughput DNA sequencing (ChIP-seq), we show that Hfq associates with hundreds of different regions of the Pseudomonas aeruginosa chromosome. These associations are abolished when transcription is inhibited, indicating that they reflect Hfq binding to transcripts during their synthesis. Analogous ChIP-seq analyses with the post-transcriptional regulator Crc reveal that it associates with many of the same nascent transcripts as Hfq, an activity we show is Hfq dependent. Our findings indicate that Hfq binds many transcripts co-transcriptionally in P. aeruginosa, often in concert with Crc, and uncover direct regulatory targets of these proteins. They also highlight a general approach for studying the interactions of RNA-binding proteins with nascent transcripts in bacteria. The binding of post-transcriptional regulators to nascent mRNAs may represent a prevalent means of controlling translation in bacteria where transcription and translation are coupled.
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Affiliation(s)
- Tracy K Kambara
- Division of Infectious Diseases, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Kathryn M Ramsey
- Division of Infectious Diseases, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Simon L Dove
- Division of Infectious Diseases, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA.
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18
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Azam MS, Vanderpool CK. Translational regulation by bacterial small RNAs via an unusual Hfq-dependent mechanism. Nucleic Acids Res 2018; 46:2585-2599. [PMID: 29294046 PMCID: PMC5861419 DOI: 10.1093/nar/gkx1286] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2017] [Revised: 12/08/2017] [Accepted: 12/21/2017] [Indexed: 01/06/2023] Open
Abstract
In bacteria, the canonical mechanism of translational repression by small RNAs (sRNAs) involves sRNA-mRNA base pairing that occludes the ribosome binding site (RBS), directly preventing translation. In this mechanism, the sRNA is the direct regulator, while the RNA chaperone Hfq plays a supporting role by stabilizing the sRNA. There are a few examples where the sRNA does not directly interfere with ribosome binding, yet translation of the target mRNA is still inhibited. Mechanistically, this non-canonical regulation by sRNAs is poorly understood. Our previous work demonstrated repression of the mannose transporter manX mRNA by the sRNA SgrS, but the regulatory mechanism was unknown. Here, we report that manX translation is controlled by a molecular role-reversal mechanism where Hfq, not the sRNA, is the direct repressor. Hfq binding adjacent to the manX RBS is required for sRNA-mediated translational repression. Translation of manX is also regulated by another sRNA, DicF, via the same non-canonical Hfq-dependent mechanism. Our results suggest that the sRNAs recruit Hfq to its binding site or stabilize the mRNA-Hfq complex. This work adds to the growing number of examples of diverse mechanisms of translational regulation by sRNAs in bacteria.
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Affiliation(s)
- Muhammad S Azam
- Department of Microbiology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Carin K Vanderpool
- Department of Microbiology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
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19
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Cho SH, Haning K, Shen W, Blome C, Li R, Yang S, Contreras LM. Identification and Characterization of 5' Untranslated Regions (5'UTRs) in Zymomonas mobilis as Regulatory Biological Parts. Front Microbiol 2017; 8:2432. [PMID: 29375488 PMCID: PMC5770649 DOI: 10.3389/fmicb.2017.02432] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Accepted: 11/23/2017] [Indexed: 01/03/2023] Open
Abstract
Regulatory RNA regions within a transcript, particularly in the 5' untranslated region (5'UTR), have been shown in a variety of organisms to control the expression levels of these mRNAs in response to various metabolites or environmental conditions. Considering the unique tolerance of Zymomonas mobilis to ethanol and the growing interest in engineering microbial strains with enhanced tolerance to industrial inhibitors, we searched natural cis-regulatory regions in this microorganism using transcriptomic data and bioinformatics analysis. Potential regulatory 5'UTRs were identified and filtered based on length, gene function, relative gene counts, and conservation in other organisms. An in vivo fluorescence-based screening system was developed to confirm the responsiveness of 36 5'UTR candidates to ethanol, acetate, and xylose stresses. UTR_ZMO0347 (5'UTR of gene ZMO0347 encoding the RNA binding protein Hfq) was found to down-regulate downstream gene expression under ethanol stress. Genomic deletion of UTR_ZMO0347 led to a general decrease of hfq expression at the transcript level and increased sensitivity for observed changes in Hfq expression at the protein level. The role of UTR_ZMO0347 and other 5'UTRs gives us insight into the regulatory network of Z. mobilis in response to stress and unlocks new strategies for engineering robust industrial strains as well as for harvesting novel responsive regulatory biological parts for controllable gene expression platforms in this organism.
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Affiliation(s)
- Seung Hee Cho
- Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX, United States
| | - Katie Haning
- Department of Chemical Engineering, Cockrell School of Engineering, University of Texas at Austin, Austin, TX, United States
| | - Wei Shen
- Hubei Key Laboratory of Industrial Biotechnology, Hubei Collaborative Innovation Center for Green Transformation of Bio-resources, Environmental Microbial Technology Center of Hubei Province, College of Life Sciences, Hubei University, Wuhan, China
| | - Cameron Blome
- Department of Chemical Engineering, Cockrell School of Engineering, University of Texas at Austin, Austin, TX, United States
| | - Runxia Li
- Hubei Key Laboratory of Industrial Biotechnology, Hubei Collaborative Innovation Center for Green Transformation of Bio-resources, Environmental Microbial Technology Center of Hubei Province, College of Life Sciences, Hubei University, Wuhan, China
| | - Shihui Yang
- Hubei Key Laboratory of Industrial Biotechnology, Hubei Collaborative Innovation Center for Green Transformation of Bio-resources, Environmental Microbial Technology Center of Hubei Province, College of Life Sciences, Hubei University, Wuhan, China
| | - Lydia M Contreras
- Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX, United States.,Department of Chemical Engineering, Cockrell School of Engineering, University of Texas at Austin, Austin, TX, United States
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20
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Chen J, Gottesman S. Hfq links translation repression to stress-induced mutagenesis in E. coli. Genes Dev 2017; 31:1382-1395. [PMID: 28794186 PMCID: PMC5580658 DOI: 10.1101/gad.302547.117] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2017] [Accepted: 07/17/2017] [Indexed: 01/08/2023]
Abstract
Here, Chen et al. show an example of Hfq repressing translation in the absence of sRNAs via major remodeling of the mRNA. They demonstrate that, by interacting with the mutS leader, Hfq serves as a critical switch that modulates bacteria from high-fidelity DNA replication to stress-induced mutagenesis. Mismatch repair (MMR) is a conserved mechanism exploited by cells to correct DNA replication errors both in growing cells and under nongrowing conditions. Hfq (host factor for RNA bacteriophage Qβ replication), a bacterial Lsm family RNA-binding protein, chaperones RNA–RNA interactions between regulatory small RNAs (sRNAs) and target messenger RNAs (mRNAs), leading to alterations of mRNA translation and/or stability. Hfq has been reported to post-transcriptionally repress the DNA MMR gene mutS in stationary phase, possibly limiting MMR to allow increased mutagenesis. Here we report that Hfq deploys dual mechanisms to control mutS expression. First, Hfq binds directly to an (AAN)3 motif within the mutS 5′ untranslated region (UTR), repressing translation in the absence of sRNA partners both in vivo and in vitro. Second, Hfq acts in a canonical pathway, promoting base-pairing of ArcZ sRNA with the mutS leader to inhibit translation. Most importantly, using pathway-specific mutS chromosomal alleles that specifically abrogate either regulatory pathway or both, we demonstrate that tight control of MutS levels in stationary phase contributes to stress-induced mutagenesis. By interacting with the mutS leader, Hfq serves as a critical switch that modulates bacteria from high-fidelity DNA replication to stress-induced mutagenesis.
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Affiliation(s)
- Jiandong Chen
- Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland 20892, USA
| | - Susan Gottesman
- Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland 20892, USA
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21
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Sonnleitner E, Prindl K, Bläsi U. The Pseudomonas aeruginosa CrcZ RNA interferes with Hfq-mediated riboregulation. PLoS One 2017; 12:e0180887. [PMID: 28686727 PMCID: PMC5501646 DOI: 10.1371/journal.pone.0180887] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Accepted: 06/22/2017] [Indexed: 12/17/2022] Open
Abstract
The RNA chaperone Hfq regulates virulence and metabolism in the opportunistic pathogen Pseudomonas aeruginosa. During carbon catabolite repression (CCR) Hfq together with the catabolite repression control protein Crc can act as a translational repressor of catabolic genes. Upon relief of CCR, the level of the Hfq-titrating RNA CrcZ is increasing, which in turn abrogates Hfq-mediated translational repression. As the interdependence of Hfq-mediated and RNA based control mechanisms is poorly understood, we explored the possibility whether the regulatory RNA CrcZ can interfere with riboregulation. We first substantiate that the P. aeruginosa Hfq is proficient and required for riboregulation of the transcriptional activator gene antR by the small RNA PrrF1-2. Our studies further revealed that CrcZ can interfere with PrrF1-2/Hfq-mediated regulation of antR. The competition for Hfq can be rationalized by the higher affinity of Hfq for CrcZ than for antR mRNA.
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Affiliation(s)
- Elisabeth Sonnleitner
- Department of Microbiology, Immunobiology and Genetics, Max F. Perutz Laboratories, Center of Molecular Biology, University of Vienna, Vienna Biocenter (VBC), Vienna, Austria
- * E-mail:
| | - Konstantin Prindl
- Department of Microbiology, Immunobiology and Genetics, Max F. Perutz Laboratories, Center of Molecular Biology, University of Vienna, Vienna Biocenter (VBC), Vienna, Austria
| | - Udo Bläsi
- Department of Microbiology, Immunobiology and Genetics, Max F. Perutz Laboratories, Center of Molecular Biology, University of Vienna, Vienna Biocenter (VBC), Vienna, Austria
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22
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Langer A, Moldovan A, Harmath C, Joyce SA, Clarke DJ, Heermann R. HexA is a versatile regulator involved in the control of phenotypic heterogeneity of Photorhabdus luminescens. PLoS One 2017; 12:e0176535. [PMID: 28448559 PMCID: PMC5407808 DOI: 10.1371/journal.pone.0176535] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Accepted: 04/12/2017] [Indexed: 12/04/2022] Open
Abstract
Phenotypic heterogeneity in microbial communities enables genetically identical organisms to behave differently even under the same environmental conditions. Photorhabdus luminescens, a bioluminescent Gram-negative bacterium, contains a complex life cycle, which involves a symbiotic interaction with nematodes as well as a pathogenic association with insect larvae. P. luminescens exists in two distinct phenotypic cell types, designated as the primary (1°) and secondary (2°) cells. The 1° cells are bioluminescent, pigmented and can support nematode growth and development. Individual 1° cells undergo phenotypic switching after prolonged cultivation and convert to 2° cells, which lack the 1° specific phenotypes. The LysR-type regulator HexA has been described as major regulator of this switching process. Here we show that HexA controls phenotypic heterogeneity in a versatile way, directly and indirectly. Expression of hexA is enhanced in 2° cells, and the corresponding regulator inhibits 1° specific traits in 2° cells. HexA does not directly affect bioluminescence, a predominant 1° specific phenotype. Since the respective luxCDABE operon is repressed at the post-transcriptional level and transcriptional levels of the RNA chaperone gene hfq are also enhanced in 2° cells, small regulatory RNAs are presumably involved that are under control of HexA. Another phenotypic trait that is specific for 1° cells is quorum sensing mediated cell clumping. The corresponding pcfABCDEF operon could be identified as the first direct target of HexA, since the regulator binds to the pcfA promoter region and thereby blocks expression of the target operon. In summary, our data show that HexA fulfills the task as repressor of 1° specific features in 2° cells in a versatile way and gives first insights into the complexity of regulating phenotypic heterogeneity in Photorhabdus bacteria.
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Affiliation(s)
- Angela Langer
- Bereich Mikrobiologie, Biozentrum Martinsried, Ludwig-Maximilians-Universität München, München, Germany
| | - Adriana Moldovan
- Bereich Mikrobiologie, Biozentrum Martinsried, Ludwig-Maximilians-Universität München, München, Germany
| | - Christian Harmath
- Bereich Mikrobiologie, Biozentrum Martinsried, Ludwig-Maximilians-Universität München, München, Germany
| | - Susan A. Joyce
- School of Microbiology and Microbiome Institute, University College Cork, Cork, Ireland
| | - David J. Clarke
- School of Microbiology and Microbiome Institute, University College Cork, Cork, Ireland
| | - Ralf Heermann
- Bereich Mikrobiologie, Biozentrum Martinsried, Ludwig-Maximilians-Universität München, München, Germany
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23
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A Unique cis-Encoded Small Noncoding RNA Is Regulating Legionella pneumophila Hfq Expression in a Life Cycle-Dependent Manner. mBio 2017; 8:mBio.02182-16. [PMID: 28074027 PMCID: PMC5225317 DOI: 10.1128/mbio.02182-16] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Legionella pneumophila is an environmental bacterium that parasitizes protozoa, but it may also infect humans, thereby causing a severe pneumonia called Legionnaires’ disease. To cycle between the environment and a eukaryotic host, L. pneumophila is regulating the expression of virulence factors in a life cycle-dependent manner: replicating bacteria do not express virulence factors, whereas transmissive bacteria are highly motile and infective. Here we show that Hfq is an important regulator in this network. Hfq is highly expressed in transmissive bacteria but is expressed at very low levels in replicating bacteria. A L. pneumophila hfq deletion mutant exhibits reduced abilities to infect and multiply in Acanthamoeba castellanii at environmental temperatures. The life cycle-dependent regulation of Hfq expression depends on a unique cis-encoded small RNA named Anti-hfq that is transcribed antisense of the hfq transcript and overlaps its 5′ untranslated region. The Anti-hfq sRNA is highly expressed only in replicating L. pneumophila where it regulates hfq expression through binding to the complementary regions of the hfq transcripts. This results in reduced Hfq protein levels in exponentially growing cells. Both the small noncoding RNA (sRNA) and hfq mRNA are bound and stabilized by the Hfq protein, likely leading to the cleavage of the RNA duplex by the endoribonuclease RNase III. In contrast, after the switch to transmissive bacteria, the sRNA is not expressed, allowing now an efficient expression of the hfq gene and consequently Hfq. Our results place Hfq and its newly identified sRNA anti-hfq in the center of the regulatory network governing L. pneumophila differentiation from nonvirulent to virulent bacteria. The abilities of L. pneumophila to replicate intracellularly and to cause disease depend on its capacity to adapt to different extra- and intracellular environmental conditions. Therefore, a timely and fine-tuned expression of virulence factors and adaptation traits is crucial. Yet, the regulatory circuits governing the life cycle of L. pneumophila from replicating to virulent bacteria are only partly uncovered. Here we show that the life cycle-dependent regulation of the RNA chaperone Hfq relies on a small regulatory RNA encoded antisense to the hfq-encoding gene through a base pairing mechanism. Furthermore, Hfq regulates its own expression in an autoregulatory loop. The discovery of this RNA regulatory mechanism in L. pneumophila is an important step forward in the understanding of how the switch from inoffensive, replicating to highly virulent, transmissive L. pneumophila is regulated.
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24
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Abstract
Over the last decade, small (often noncoding) RNA molecules have been discovered as important regulators influencing myriad aspects of bacterial physiology and virulence. In particular, small RNAs (sRNAs) have been implicated in control of both primary and secondary metabolic pathways in many bacterial species. This chapter describes characteristics of the major classes of sRNA regulators, and highlights what is known regarding their mechanisms of action. Specific examples of sRNAs that regulate metabolism in gram-negative bacteria are discussed, with a focus on those that regulate gene expression by base pairing with mRNA targets to control their translation and stability.
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25
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Ellis MJ, Haniford DB. Riboregulation of bacterial and archaeal transposition. WILEY INTERDISCIPLINARY REVIEWS-RNA 2016; 7:382-98. [DOI: 10.1002/wrna.1341] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2015] [Revised: 01/07/2016] [Accepted: 01/10/2016] [Indexed: 12/31/2022]
Affiliation(s)
- Michael J. Ellis
- Department of Biochemistry; University of Western Ontario; London Canada
| | - David B. Haniford
- Department of Biochemistry; University of Western Ontario; London Canada
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26
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Feliciano JR, Grilo AM, Guerreiro SI, Sousa SA, Leitão JH. Hfq: a multifaceted RNA chaperone involved in virulence. Future Microbiol 2015; 11:137-51. [PMID: 26685037 DOI: 10.2217/fmb.15.128] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Hfq has emerged in recent years as a master regulator of gene expression in bacteria, mainly due to its ability to mediate the interaction of small noncoding RNAs with their mRNA targets, including those related to virulence in Gram-negative bacteria. In this work, we review current knowledge on the involvement of Hfq in the regulation of virulence traits related to secretion systems, alternative sigma factors, outer membrane proteins, polysaccharides and iron metabolism. Recent data from transcriptomics and proteomics studies performed for major pathogens are included. We also summarize and correlate current knowledge on how Hfq protein impacts pathogenicity of bacterial pathogens.
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Affiliation(s)
- Joana R Feliciano
- iBB - Instituto de Bioengenharia e Biociências, Instituto Superior Técnico, Universidade de Lisboa. Av. Rovisco Pais, 1049-001 Lisboa, Portugal
| | | | - Soraia I Guerreiro
- iBB - Instituto de Bioengenharia e Biociências, Instituto Superior Técnico, Universidade de Lisboa. Av. Rovisco Pais, 1049-001 Lisboa, Portugal
| | - Sílvia A Sousa
- iBB - Instituto de Bioengenharia e Biociências, Instituto Superior Técnico, Universidade de Lisboa. Av. Rovisco Pais, 1049-001 Lisboa, Portugal
| | - Jorge H Leitão
- iBB - Instituto de Bioengenharia e Biociências, Instituto Superior Técnico, Universidade de Lisboa. Av. Rovisco Pais, 1049-001 Lisboa, Portugal.,Departamento de Bioengenharia, Instituto Superior Técnico, Universidade de Lisboa. Av. Rovisco Pais, 1049-001 Lisboa, Portugal
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27
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Sagawa S, Shin JE, Hussein R, Lim HN. Paradoxical suppression of small RNA activity at high Hfq concentrations due to random-order binding. Nucleic Acids Res 2015; 43:8502-15. [PMID: 26261213 PMCID: PMC4787825 DOI: 10.1093/nar/gkv777] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2015] [Accepted: 07/20/2015] [Indexed: 11/15/2022] Open
Abstract
Small RNAs (sRNAs) are important regulators of gene expression during bacterial stress and pathogenesis. sRNAs act by forming duplexes with mRNAs to alter their translation and degradation. In some bacteria, duplex formation is mediated by the Hfq protein, which can bind the sRNA and mRNA in each pair in a random order. Here we investigate the consequences of this random-order binding and experimentally demonstrate that it can counterintuitively cause high Hfq concentrations to suppress rather than promote sRNA activity in Escherichia coli. As a result, maximum sRNA activity occurs when the Hfq concentration is neither too low nor too high relative to the sRNA and mRNA concentrations (‘Hfq set-point’). We further show with models and experiments that random-order binding combined with the formation of a dead-end mRNA–Hfq complex causes high concentrations of an mRNA to inhibit its own duplex formation by sequestering Hfq. In such cases, maximum sRNA activity requires an optimal mRNA concentration (‘mRNA set-point’) as well as an optimal Hfq concentration. The Hfq and mRNA set-points generate novel regulatory properties that can be harnessed by native and synthetic gene circuits to provide greater control over sRNA activity, generate non-monotonic responses and enhance the robustness of expression.
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Affiliation(s)
- Shiori Sagawa
- Department of Integrative Biology, University of California, Berkeley, CA 94720-3140, USA
| | - Jung-Eun Shin
- Department of Integrative Biology, University of California, Berkeley, CA 94720-3140, USA
| | - Razika Hussein
- Department of Integrative Biology, University of California, Berkeley, CA 94720-3140, USA
| | - Han N Lim
- Department of Integrative Biology, University of California, Berkeley, CA 94720-3140, USA
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Ellis MJ, Trussler RS, Haniford DB. Hfq binds directly to the ribosome-binding site of IS10 transposase mRNA to inhibit translation. Mol Microbiol 2015; 96:633-50. [PMID: 25649688 PMCID: PMC5006887 DOI: 10.1111/mmi.12961] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/02/2015] [Indexed: 12/31/2022]
Abstract
Hfq is a critical component of post‐transcriptional regulatory networks in most bacteria. It usually functions as a chaperone for base‐pairing small RNAs, although non‐canonical regulatory roles are continually emerging. We have previously shown that Hfq represses IS10/Tn10 transposase expression through both antisense RNA‐dependent and independent mechanisms. In the current work, we set out to define the regulatory role of Hfq in the absence of the IS10 antisense RNA. We show here that an interaction between the distal surface of Hfq and the ribosome‐binding site of transposase mRNA (RNA‐IN) is required for repressing translation initiation. Additionally, this interaction was critical for the in vivo association of Hfq and RNA‐IN. Finally, we present evidence that the small RNA ChiX activates transposase expression by titrating Hfq away from RNA‐IN. The current results are considered in the broader context of Hfq biology and implications for Hfq titration by ChiX are discussed.
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Affiliation(s)
- Michael J Ellis
- Department of Biochemistry, University of Western Ontario, London, Ontario, N6A 5C1, Canada
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Van Assche E, Van Puyvelde S, Vanderleyden J, Steenackers HP. RNA-binding proteins involved in post-transcriptional regulation in bacteria. Front Microbiol 2015; 6:141. [PMID: 25784899 PMCID: PMC4347634 DOI: 10.3389/fmicb.2015.00141] [Citation(s) in RCA: 93] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2014] [Accepted: 02/06/2015] [Indexed: 11/19/2022] Open
Abstract
Post-transcriptional regulation is a very important mechanism to control gene expression in changing environments. In the past decade, a lot of interest has been directed toward the role of small RNAs (sRNAs) in bacterial post-transcriptional regulation. However, sRNAs are not the only molecules controlling gene expression at this level, RNA-binding proteins (RBPs) play an important role as well. CsrA and Hfq are the two best studied bacterial proteins of this type, but recently, additional proteins involved in post-transcriptional control have been identified. This review focuses on the general working mechanisms of post-transcriptionally active RBPs, which include (i) adaptation of the susceptibility of mRNAs and sRNAs to RNases, (ii) modulating the accessibility of the ribosome binding site of mRNAs, (iii) recruiting and assisting in the interaction of mRNAs with other molecules and (iv) regulating transcription terminator/antiterminator formation, and gives an overview of both the well-studied and the newly identified proteins that are involved in post-transcriptional regulatory processes. Additionally, the post-transcriptional mechanisms by which the expression or the activity of these proteins is regulated, are described. For many of the newly identified proteins, however, mechanistic questions remain. Most likely, more post-transcriptionally active proteins will be identified in the future.
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Affiliation(s)
- Elke Van Assche
- Centre of Microbial and Plant Genetics, Department of Molecular and Microbial Systems, KU Leuven Leuven, Belgium
| | - Sandra Van Puyvelde
- Centre of Microbial and Plant Genetics, Department of Molecular and Microbial Systems, KU Leuven Leuven, Belgium
| | - Jos Vanderleyden
- Centre of Microbial and Plant Genetics, Department of Molecular and Microbial Systems, KU Leuven Leuven, Belgium
| | - Hans P Steenackers
- Centre of Microbial and Plant Genetics, Department of Molecular and Microbial Systems, KU Leuven Leuven, Belgium
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Möller P, Overlöper A, Förstner KU, Wen TN, Sharma CM, Lai EM, Narberhaus F. Profound impact of Hfq on nutrient acquisition, metabolism and motility in the plant pathogen Agrobacterium tumefaciens. PLoS One 2014; 9:e110427. [PMID: 25330313 PMCID: PMC4201532 DOI: 10.1371/journal.pone.0110427] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2014] [Accepted: 09/14/2014] [Indexed: 01/18/2023] Open
Abstract
As matchmaker between mRNA and sRNA interactions, the RNA chaperone Hfq plays a key role in riboregulation of many bacteria. Often, the global influence of Hfq on the transcriptome is reflected by substantially altered proteomes and pleiotropic phenotypes in hfq mutants. Using quantitative proteomics and co-immunoprecipitation combined with RNA-sequencing (RIP-seq) of Hfq-bound RNAs, we demonstrate the pervasive role of Hfq in nutrient acquisition, metabolism and motility of the plant pathogen Agrobacterium tumefaciens. 136 of 2544 proteins identified by iTRAQ (isobaric tags for relative and absolute quantitation) were affected in the absence of Hfq. Most of them were associated with ABC transporters, general metabolism and motility. RIP-seq of chromosomally encoded Hfq3xFlag revealed 1697 mRNAs and 209 non-coding RNAs (ncRNAs) associated with Hfq. 56 ncRNAs were previously undescribed. Interestingly, 55% of the Hfq-bound ncRNAs were encoded antisense (as) to a protein-coding sequence suggesting that A. tumefaciens Hfq plays an important role in asRNA-target interactions. The exclusive enrichment of 296 mRNAs and 31 ncRNAs under virulence conditions further indicates a role for post-transcriptional regulation in A. tumefaciens-mediated plant infection. On the basis of the iTRAQ and RIP-seq data, we assembled a comprehensive model of the Hfq core regulon in A. tumefaciens.
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Affiliation(s)
- Philip Möller
- Microbial Biology, Ruhr University Bochum, Bochum, Germany
| | | | - Konrad U. Förstner
- Research Center for Infectious Diseases (ZINF), Julius-Maximilian's University of Würzburg, Würzburg, Germany
| | - Tuan-Nan Wen
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan
| | - Cynthia M. Sharma
- Research Center for Infectious Diseases (ZINF), Julius-Maximilian's University of Würzburg, Würzburg, Germany
| | - Erh-Min Lai
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan
| | - Franz Narberhaus
- Microbial Biology, Ruhr University Bochum, Bochum, Germany
- * E-mail:
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Caillet J, Gracia C, Fontaine F, Hajnsdorf E. Clostridium difficile Hfq can replace Escherichia coli Hfq for most of its function. RNA (NEW YORK, N.Y.) 2014; 20:1567-1578. [PMID: 25147238 PMCID: PMC4174439 DOI: 10.1261/rna.043372.113] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/12/2013] [Accepted: 05/31/2014] [Indexed: 06/03/2023]
Abstract
A gene for the Hfq protein is present in the majority of sequenced bacterial genomes. Its characteristic hexameric ring-like core structure is formed by the highly conserved N-terminal regions. In contrast, the C-terminal forms an extension, which varies in length, lacks homology, and is predicted to be unstructured. In Gram-negative bacteria, Hfq facilitates the pairing of sRNAs with their mRNA target and thus affects gene expression, either positively or negatively, and modulates sRNA degradation. In Gram-positive bacteria, its role is still poorly characterized. Numerous sRNAs have been detected in many Gram-positive bacteria, but it is not yet known whether these sRNAs act in association with Hfq. Compared with all other Hfqs, the C. difficile Hfq exhibits an unusual C-terminal sequence with 75% asparagine and glutamine residues, while the N-terminal core part is more conserved. To gain insight into the functionality of the C. difficile Hfq (Cd-Hfq) protein in processes regulated by sRNAs, we have tested the ability of Cd-Hfq to fulfill the functions of the E. coli Hfq (Ec-Hfq) by examining various functions associated with Hfq in both positive and negative controls of gene expression. We found that Cd-Hfq substitutes for most but not all of the tested functions of the Ec-Hfq protein. We also investigated the role of the C-terminal part of the Hfq proteins. We found that the C-terminal part of both Ec-Hfq and Cd-Hfq is not essential but contributes to some functions of both the E. coli and C. difficile chaperons.
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Affiliation(s)
- Joel Caillet
- CNRS FRE3630 (previously UPR9073), University Paris Diderot, Sorbonne Paris Cité, Institut de Biologie Physico-Chimique, 75005 Paris, France
| | - Céline Gracia
- CNRS FRE3630 (previously UPR9073), University Paris Diderot, Sorbonne Paris Cité, Institut de Biologie Physico-Chimique, 75005 Paris, France
| | - Fanette Fontaine
- CNRS FRE3630 (previously UPR9073), University Paris Diderot, Sorbonne Paris Cité, Institut de Biologie Physico-Chimique, 75005 Paris, France
| | - Eliane Hajnsdorf
- CNRS FRE3630 (previously UPR9073), University Paris Diderot, Sorbonne Paris Cité, Institut de Biologie Physico-Chimique, 75005 Paris, France
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Sonnleitner E, Bläsi U. Regulation of Hfq by the RNA CrcZ in Pseudomonas aeruginosa carbon catabolite repression. PLoS Genet 2014; 10:e1004440. [PMID: 24945892 PMCID: PMC4063720 DOI: 10.1371/journal.pgen.1004440] [Citation(s) in RCA: 122] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2014] [Accepted: 04/30/2014] [Indexed: 01/10/2023] Open
Abstract
Carbon Catabolite repression (CCR) allows a fast adaptation of Bacteria to changing nutrient supplies. The Pseudomonas aeruginosa (PAO1) catabolite repression control protein (Crc) was deemed to act as a translational regulator, repressing functions involved in uptake and utilization of carbon sources. However, Crc of PAO1 was recently shown to be devoid of RNA binding activity. In this study the RNA chaperone Hfq was identified as the principle post-transcriptional regulator of CCR in PAO1. Hfq is shown to bind to A-rich sequences within the ribosome binding site of the model mRNA amiE, and to repress translation in vitro and in vivo. We further report that Crc plays an unknown ancillary role, as full-fledged repression of amiE and other CCR-regulated mRNAs in vivo required its presence. Moreover, we show that the regulatory RNA CrcZ, transcription of which is augmented when CCR is alleviated, binds to Hfq with high affinity. This study on CCR in PAO1 revealed a novel concept for Hfq function, wherein the regulatory RNA CrcZ acts as a decoy to abrogate Hfq-mediated translational repression of catabolic genes and thus highlights the central role of RNA based regulation in CCR of PAO1. Carbon assimilation in Bacteria is governed by a mechanism known as carbon catabolite repression (CCR). In contrast to several other bacterial clades CCR in Pseudomonas species appears to be primarily regulated at the post-transcriptional level. In this study, we have identified the RNA chaperone Hfq as the principle post-transcriptional regulator of CCR in P. aeruginosa (PAO1). Hfq is shown to act as a translational regulator and to prevent ribosome loading through binding to A-rich sequences within the ribosome binding site of mRNAs, which encode enzymes involved in carbon utilization. It has been previously shown that the synthesis of the RNA CrcZ is augmented in the presence of non-preferred carbon sources. Here, we show that the CrcZ RNA binds to and sequesters Hfq, which in turn abrogates Hfq-mediated translational repression of mRNAs, the encoded functions of which are required for the breakdown of non-preferred carbon sources. This novel mechanistic twist on Hfq function not only highlights the central role of RNA based regulation in CCR of PAO1 but also broadens the view of Hfq-mediated post-transcriptional mechanisms.
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Affiliation(s)
- Elisabeth Sonnleitner
- Department of Microbiology, Immunobiology and Genetics, Max F. Perutz Laboratories, Center of Molecular Biology, University of Vienna, Vienna, Austria
- * E-mail: (ES); (UB)
| | - Udo Bläsi
- Department of Microbiology, Immunobiology and Genetics, Max F. Perutz Laboratories, Center of Molecular Biology, University of Vienna, Vienna, Austria
- * E-mail: (ES); (UB)
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Ramos CG, Grilo AM, Sousa SA, Feliciano JR, da Costa PJP, Leitão JH. Regulation of Hfq mRNA and protein levels in Escherichia coli and Pseudomonas aeruginosa by the Burkholderia cenocepacia MtvR sRNA. PLoS One 2014; 9:e98813. [PMID: 24901988 PMCID: PMC4046987 DOI: 10.1371/journal.pone.0098813] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2014] [Accepted: 05/07/2014] [Indexed: 11/19/2022] Open
Abstract
Small non-coding RNAs (sRNAs) are important players of gene expression regulation in bacterial pathogens. MtvR is a 136-nucleotide long sRNA previously identified in the human pathogen Burkholderia cenocepacia J2315 and with homologues restricted to bacteria of the Burkholderia cepacia complex. In this work we have investigated the effects of expressing MtvR in Escherichia coli and Pseudomonas aeruginosa. Results are presented showing that MtvR negatively regulates the hfq mRNA levels in both bacterial species. In the case of E. coli, this negative regulation is shown to involve binding of MtvR to the 5′-UTR region of the hfqEc mRNA. Results presented also show that expression of MtvR in E. coli and P. aeruginosa originates multiple phenotypes, including reduced resistance to selected stresses, biofilm formation ability, and increased susceptibility to various antibiotics.
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Affiliation(s)
- Christian G. Ramos
- Department of Bioengineering and Institute for Biotechnology and Bioengineering, Instituto Superior Técnico, Universidade de Lisboa, Lisboa, Portugal
| | - André M. Grilo
- Department of Bioengineering and Institute for Biotechnology and Bioengineering, Instituto Superior Técnico, Universidade de Lisboa, Lisboa, Portugal
| | - Sílvia A. Sousa
- Department of Bioengineering and Institute for Biotechnology and Bioengineering, Instituto Superior Técnico, Universidade de Lisboa, Lisboa, Portugal
| | - Joana R. Feliciano
- Department of Bioengineering and Institute for Biotechnology and Bioengineering, Instituto Superior Técnico, Universidade de Lisboa, Lisboa, Portugal
| | - Paulo J. P. da Costa
- Department of Bioengineering and Institute for Biotechnology and Bioengineering, Instituto Superior Técnico, Universidade de Lisboa, Lisboa, Portugal
| | - Jorge H. Leitão
- Department of Bioengineering and Institute for Biotechnology and Bioengineering, Instituto Superior Técnico, Universidade de Lisboa, Lisboa, Portugal
- * E-mail:
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Moreno R, Hernández-Arranz S, La Rosa R, Yuste L, Madhushani A, Shingler V, Rojo F. The Crc and Hfq proteins of Pseudomonas putida cooperate in catabolite repression and formation of ribonucleic acid complexes with specific target motifs. Environ Microbiol 2014; 17:105-18. [PMID: 24803210 DOI: 10.1111/1462-2920.12499] [Citation(s) in RCA: 83] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2014] [Accepted: 04/28/2014] [Indexed: 12/22/2022]
Abstract
The Crc protein is a global regulator that has a key role in catabolite repression and optimization of metabolism in Pseudomonads. Crc inhibits gene expression post-transcriptionally, preventing translation of mRNAs bearing an AAnAAnAA motif [the catabolite activity (CA) motif] close to the translation start site. Although Crc was initially believed to bind RNA by itself, this idea was recently challenged by results suggesting that a protein co-purifying with Crc, presumably the Hfq protein, could account for the detected RNA-binding activity. Hfq is an abundant protein that has a central role in post-transcriptional gene regulation. Herein, we show that the Pseudomonas putida Hfq protein can recognize the CA motifs of RNAs through its distal face and that Crc facilitates formation of a more stable complex at these targets. Crc was unable to bind RNA in the absence of Hfq. However, pull-down assays showed that Crc and Hfq can form a co-complex with RNA containing a CA motif in vitro. Inactivation of the hfq or the crc gene impaired catabolite repression to a similar extent. We propose that Crc and Hfq cooperate in catabolite repression, probably through forming a stable co-complex with RNAs containing CA motifs to result in inhibition of translation initiation.
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Affiliation(s)
- Renata Moreno
- Departamento de Biotecnología Microbiana, Centro Nacional de Biotecnología, CSIC, Darwin 3, Cantoblanco, 28049, Madrid, Spain
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Torres-Quesada O, Reinkensmeier J, Schlüter JP, Robledo M, Peregrina A, Giegerich R, Toro N, Becker A, Jiménez-Zurdo JI. Genome-wide profiling of Hfq-binding RNAs uncovers extensive post-transcriptional rewiring of major stress response and symbiotic regulons in Sinorhizobium meliloti. RNA Biol 2014; 11:563-79. [PMID: 24786641 DOI: 10.4161/rna.28239] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The RNA chaperone Hfq is a global post-transcriptional regulator in bacteria. Here, we used RNAseq to analyze RNA populations from the legume symbiont Sinorhizobium meliloti that were co-immunoprecipitated (CoIP-RNA) with a FLAG-tagged Hfq in five growth/stress conditions. Hfq-bound transcripts (1315) were largely identified in stressed bacteria and derived from small RNAs (sRNAs), both trans-encoded (6.4%) and antisense (asRNAs; 6.3%), and mRNAs (86%). Pull-down with Hfq recovered a small proportion of annotated S. meliloti sRNAs (14% of trans-sRNAs and 2% of asRNAs) suggesting a discrete impact of this protein in sRNA pathways. Nonetheless, Hfq selectively stabilized CoIP-enriched sRNAs, anticipating that these interactions are functionally significant. Transcription of 26 Hfq-bound sRNAs was predicted to occur from promoters recognized by the major stress σ factors σ(E2) or σ(H1/2). Recovery rates of sRNAs in each of the CoIP-RNA libraries suggest a large impact of Hfq-assisted riboregulation in S. meliloti osmoadaptation. Hfq directly targeted 18% of the predicted S. meliloti mRNAs, which encode functionally diverse proteins involved in transport and metabolism, σ(E2)-dependent stress responses, quorum sensing, flagella biosynthesis, ribosome, and membrane assembly or symbiotic nitrogen fixation. Canonical targeting of the 5' regions of two of the ABC transporter mRNAs by the homologous Hfq-binding AbcR1 and AbcR2 sRNAs leading to inhibition of protein synthesis was confirmed in vivo. We therefore provide a comprehensive resource for the systems-level deciphering of hitherto unexplored S. meliloti stress and symbiotic post-transcriptional regulons and the identification of Hfq-dependent sRNA-mRNA regulatory pairs.
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Affiliation(s)
- Omar Torres-Quesada
- Grupo de Ecología Genética de la Rizosfera; Estación Experimental del Zaidín; Consejo Superior de Investigaciones Científicas; CSIC, Granada, Spain
| | - Jan Reinkensmeier
- Center for Biotechnology (CeBiTec); Bielefeld University; Bielefeld, Germany
| | - Jan-Philip Schlüter
- LOEWE Center for Synthetic Microbiology (SYNMIKRO) and Department of Biology; Philipps-Universität Marburg; Marburg, Germany
| | - Marta Robledo
- LOEWE Center for Synthetic Microbiology (SYNMIKRO) and Department of Biology; Philipps-Universität Marburg; Marburg, Germany
| | - Alexandra Peregrina
- Grupo de Ecología Genética de la Rizosfera; Estación Experimental del Zaidín; Consejo Superior de Investigaciones Científicas; CSIC, Granada, Spain
| | - Robert Giegerich
- Center for Biotechnology (CeBiTec); Bielefeld University; Bielefeld, Germany
| | - Nicolás Toro
- Grupo de Ecología Genética de la Rizosfera; Estación Experimental del Zaidín; Consejo Superior de Investigaciones Científicas; CSIC, Granada, Spain
| | - Anke Becker
- LOEWE Center for Synthetic Microbiology (SYNMIKRO) and Department of Biology; Philipps-Universität Marburg; Marburg, Germany
| | - Jose I Jiménez-Zurdo
- Grupo de Ecología Genética de la Rizosfera; Estación Experimental del Zaidín; Consejo Superior de Investigaciones Científicas; CSIC, Granada, Spain
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Robinson KE, Orans J, Kovach AR, Link TM, Brennan RG. Mapping Hfq-RNA interaction surfaces using tryptophan fluorescence quenching. Nucleic Acids Res 2013; 42:2736-49. [PMID: 24288369 PMCID: PMC3936774 DOI: 10.1093/nar/gkt1171] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Hfq is a posttranscriptional riboregulator and RNA chaperone that binds small RNAs and target mRNAs to effect their annealing and message-specific regulation in response to environmental stressors. Structures of Hfq-RNA complexes indicate that U-rich sequences prefer the proximal face and A-rich sequences the distal face; however, the Hfq-binding sites of most RNAs are unknown. Here, we present an Hfq-RNA mapping approach that uses single tryptophan-substituted Hfq proteins, all of which retain the wild-type Hfq structure, and tryptophan fluorescence quenching (TFQ) by proximal RNA binding. TFQ properly identified the respective distal and proximal binding of A15 and U6 RNA to Gram-negative Escherichia coli (Ec) Hfq and the distal face binding of (AA)3A, (AU)3A and (AC)3A to Gram-positive Staphylococcus aureus (Sa) Hfq. The inability of (GU)3G to bind the distal face of Sa Hfq reveals the (R-L)n binding motif is a more restrictive (A-L)n binding motif. Remarkably Hfq from Gram-positive Listeria monocytogenes (Lm) binds (GU)3G on its proximal face. TFQ experiments also revealed the Ec Hfq (A-R-N)n distal face-binding motif should be redefined as an (A-A-N)n binding motif. TFQ data also demonstrated that the 5'-untranslated region of hfq mRNA binds both the proximal and distal faces of Ec Hfq and the unstructured C-terminus.
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Affiliation(s)
- Kirsten E Robinson
- Department of Biochemistry, Duke University, Durham, NC 27710, USA and Department of Biochemistry and Molecular Biology, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
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Jutras BL, Jones GS, Verma A, Brown NA, Antonicello AD, Chenail AM, Stevenson B. Posttranscriptional self-regulation by the Lyme disease bacterium's BpuR DNA/RNA-binding protein. J Bacteriol 2013; 195:4915-23. [PMID: 23974034 PMCID: PMC3807498 DOI: 10.1128/jb.00819-13] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2013] [Accepted: 08/21/2013] [Indexed: 01/21/2023] Open
Abstract
Bacteria require explicit control over their proteomes in order to compete and survive in dynamic environments. The Lyme disease spirochete Borrelia burgdorferi undergoes substantial protein profile changes during its cycling between vector ticks and vertebrate hosts. In an effort to understand regulation of these transitions, we recently isolated and functionally characterized the borrelial nucleic acid-binding protein BpuR, a PUR domain-containing protein. We now report that this regulatory protein governs its own synthesis through direct interactions with bpuR mRNA. In vitro and in vivo techniques indicate that BpuR binds with high affinity and specificity to the 5' region of its message, thereby inhibiting translation. This negative feedback could permit the bacteria to fine-tune cellular BpuR concentrations. These data add to the understanding of this newly described class of prokaryotic DNA- and RNA-binding regulatory proteins.
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Affiliation(s)
| | - Grant S. Jones
- Department of Microbiology, Immunology, and Molecular Genetics, University of Kentucky College of Medicine, Lexington, Kentucky, USA
| | | | - Nicholas A. Brown
- Department of Microbiology, Immunology, and Molecular Genetics, University of Kentucky College of Medicine, Lexington, Kentucky, USA
| | - Alyssa D. Antonicello
- Department of Microbiology, Immunology, and Molecular Genetics, University of Kentucky College of Medicine, Lexington, Kentucky, USA
| | - Alicia M. Chenail
- Department of Microbiology, Immunology, and Molecular Genetics, University of Kentucky College of Medicine, Lexington, Kentucky, USA
| | - Brian Stevenson
- Department of Microbiology, Immunology, and Molecular Genetics, University of Kentucky College of Medicine, Lexington, Kentucky, USA
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The RNA chaperone Hfq promotes fitness of Actinobacillus pleuropneumoniae during porcine pleuropneumonia. Infect Immun 2013; 81:2952-61. [PMID: 23732171 DOI: 10.1128/iai.00392-13] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Actinobacillus pleuropneumoniae is the etiological agent of porcine pleuropneumonia, an economically important disease of pigs. The hfq gene in A. pleuropneumoniae, encoding the RNA chaperone and posttranscriptional regulator Hfq, is upregulated during infection of porcine lungs. To investigate the role of this in vivo-induced gene in A. pleuropneumoniae, an hfq mutant strain was constructed. The hfq mutant was defective in biofilm formation on abiotic surfaces. The level of pgaC transcript, encoding the biosynthesis of poly-β-1,6-N-acetylglucosamine (PNAG), a major biofilm matrix component, was lower and PNAG content was 10-fold lower in the hfq mutant than in the wild-type strain. When outer membrane proteins were examined, cysteine synthase, implicated in resistance to oxidative stress and tellurite, was not found at detectable levels in the absence of Hfq. The hfq mutant displayed enhanced sensitivity to superoxide generated by methyl viologen and tellurite. These phenotypes were readily reversed by complementation with the hfq gene expressed from its native promoter. The role of Hfq in the fitness of A. pleuropneumoniae was assessed in a natural host infection model. The hfq mutant failed to colonize porcine lungs and was outcompeted by the wild-type strain (median competitive index of 2 × 10(-5)). Our data demonstrate that the in vivo-induced gene hfq is involved in the regulation of PNAG-dependent biofilm formation, resistance to superoxide stress, and the fitness and virulence of A. pleuropneumoniae in pigs and begin to elucidate the role of an in vivo-induced gene in the pathogenesis of pleuropneumonia.
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MtvR is a global small noncoding regulatory RNA in Burkholderia cenocepacia. J Bacteriol 2013; 195:3514-23. [PMID: 23729649 DOI: 10.1128/jb.00242-13] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Burkholderia cenocepacia J2315 is a highly epidemic and transmissible clinical isolate of the Burkholderia cepacia complex (Bcc), a group of bacteria causing life-threatening respiratory infections among cystic fibrosis patients. This work describes the functional analysis of the 136-nucleotide (nt)-long MtvR small noncoding RNA (sRNA) from the Bcc member B. cenocepacia J2315, with homologues restricted to the genus Burkholderia. Bioinformatic target predictions revealed a total of 309 mRNAs to be putative MtvR targets. The mRNA levels corresponding to 17 of 19 selected genes were found to be affected when MtvR was either overexpressed or silenced. Analysis of the interaction between MtvR and the hfq mRNA, one of its targets, showed that the sRNA binds exclusively to the 5' untranslated region (UTR) of the hfq mRNA. This interaction resulted in decreased protein synthesis, suggesting a negative regulatory effect of MtvR on the RNA chaperone Hfq. Bacterial strains with MtvR silenced or overexpressed exhibited pleiotropic phenotypes related to growth and survival after several stresses, swimming and swarming motilities, biofilm formation, resistance to antibiotics, and ability to colonize and kill the nematode Caenorhabditis elegans. Together, the results indicate that the MtvR sRNA is a major posttranscriptional regulator in B. cenocepacia.
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Ross JA, Ellis MJ, Hossain S, Haniford DB. Hfq restructures RNA-IN and RNA-OUT and facilitates antisense pairing in the Tn10/IS10 system. RNA (NEW YORK, N.Y.) 2013; 19:670-84. [PMID: 23510801 PMCID: PMC3677282 DOI: 10.1261/rna.037747.112] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2012] [Accepted: 02/11/2013] [Indexed: 05/23/2023]
Abstract
Hfq functions in post-transcriptional gene regulation in a wide range of bacteria, usually by promoting base-pairing of mRNAs and trans-encoded sRNAs that share partial sequence complementarity. It is less clear if Hfq is required for pairing of cis-encoded RNAs (i.e., antisense RNAs) with their target mRNAs. In the current work, we have characterized the interactions between Escherichia coli Hfq and the components of the Tn10/IS10 antisense system, RNA-IN and RNA-OUT. We show that Hfq interacts with RNA-OUT through its proximal RNA-binding surface, as is typical for Hfq and trans-encoded sRNAs. In contrast, RNA-IN binds both proximal and distal RNA-binding surfaces in Hfq with a higher affinity for the latter, as is typical for mRNA interactions in canonical sRNA-mRNA pairs. Importantly, an amino acid substitution in Hfq that interferes with RNA binding to the proximal site negatively impacts RNA-IN:OUT pairing in vitro and suppresses the ability of Hfq to negatively regulate IS10 transposition in vivo. We also show that Hfq binding to RNA-IN and RNA-OUT alters secondary structure elements in both of these RNAs and speculate that this could be important in how Hfq facilitates RNA-IN:OUT pairing. Based on the results presented here, we suggest that Hfq could be involved in regulating RNA pairing in other antisense systems, including systems encoded by other transposable elements.
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42
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New insights into small RNA-dependent translational regulation in prokaryotes. Trends Genet 2013; 29:92-8. [DOI: 10.1016/j.tig.2012.10.004] [Citation(s) in RCA: 83] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2012] [Revised: 09/14/2012] [Accepted: 10/04/2012] [Indexed: 12/16/2022]
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Ramos CG, da Costa PJP, Döring G, Leitão JH. The novel cis-encoded small RNA h2cR is a negative regulator of hfq2 in Burkholderia cenocepacia. PLoS One 2012; 7:e47896. [PMID: 23082228 PMCID: PMC3474761 DOI: 10.1371/journal.pone.0047896] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2012] [Accepted: 09/17/2012] [Indexed: 12/16/2022] Open
Abstract
Small non-coding regulatory RNAs (sRNAs) post-transcriptionally affect multiple phenotypes in prokaryotes and eukaryotes, yet most of the underlying regulatory mechanisms and the nature of the target mRNAs remain unclear. Here we report the identification and functional analysis of the novel cis-encoded sRNA h2cR, from the human opportunistic pathogen Burkholderia cenocepacia J2315. The sRNA was found to negatively regulate the hfq2 mRNA, through binding to part of the 5′-UTR region of the hfq2 mRNA, resulting in accelerated hfq2 mRNA decay and reduced protein levels in exponentially growing cells. Both the h2cR transcript and the hfq2 mRNA are stabilized by the other B. cenocepacia RNA chaperone, Hfq. Infection experiments using the nematode Caenorhabditis elegans revealed that down-regulation of Hfq2 by h2cR decreases the B. cenocepacia ability to colonize and persist within the nematode, suggesting a role for h2cR on bacterial persistence in the host.
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Affiliation(s)
- Christian G. Ramos
- Institute for Biotechnology and Bioengineering, Instituto Superior Técnico, Universidade Técnica de Lisboa, Lisboa, Portugal
| | - Paulo J. P. da Costa
- Institute for Biotechnology and Bioengineering, Instituto Superior Técnico, Universidade Técnica de Lisboa, Lisboa, Portugal
| | - Gerd Döring
- Institut für Medizinische Mikrobiologie und Hygiene, University of Tübingen, Tübingen, Germany
| | - Jorge H. Leitão
- Institute for Biotechnology and Bioengineering, Instituto Superior Técnico, Universidade Técnica de Lisboa, Lisboa, Portugal
- Department of Bioengineering, Instituto Superior Técnico, Universidade Técnica de Lisboa, Lisboa, Portugal
- * E-mail:
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44
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Multiple activities of RNA-binding proteins S1 and Hfq. Biochimie 2012; 94:1544-53. [DOI: 10.1016/j.biochi.2012.02.010] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2011] [Accepted: 02/10/2012] [Indexed: 01/16/2023]
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Murina VN, Nikulin AD. RNA-binding Sm-like proteins of bacteria and archaea. similarity and difference in structure and function. BIOCHEMISTRY (MOSCOW) 2012; 76:1434-49. [PMID: 22339597 DOI: 10.1134/s0006297911130050] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
RNA-binding proteins play a significant role in many processes of RNA metabolism, such as splicing and processing, regulation of DNA transcription and RNA translation, etc. Among the great number of RNA-binding proteins, so-called RNA-chaperones occupy an individual niche; they were named for their ability to assist RNA molecules to gain their accurate native spatial structure. When binding with RNAs, they possess the capability of altering (melting) their secondary structure, thus providing a possibility for formation of necessary intramolecular contacts between individual RNA sites for proper folding. These proteins also have an additional helper function in RNA-RNA and RNA-protein interactions. Members of such class of the RNA-binding protein family are Sm and Sm-like proteins (Sm-Like, LSm). The presence of these proteins in bacteria, archaea, and eukaryotes emphasizes their biological significance. These proteins are now attractive for researchers because of their implication in many processes associated with RNAs in bacterial and archaeal cells. This review is focused on a comparison of architecture of bacterial and archaeal LSm proteins and their interaction with different RNA molecules.
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Affiliation(s)
- V N Murina
- Institute of Protein Research, Russian Academy of Sciences, Pushchino, Moscow Region, Russia
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46
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Sobrero P, Valverde C. The bacterial protein Hfq: much more than a mere RNA-binding factor. Crit Rev Microbiol 2012; 38:276-99. [DOI: 10.3109/1040841x.2012.664540] [Citation(s) in RCA: 116] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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47
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The RNA chaperone Hfq regulates antibiotic biosynthesis in the rhizobacterium Pseudomonas aeruginosa M18. J Bacteriol 2012; 194:2443-57. [PMID: 22427627 DOI: 10.1128/jb.00029-12] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
The rhizosphere microbe Pseudomonas aeruginosa M18 shows strong antifungal activities, mainly due to the biosynthesis of antibiotics like pyoluteorin (Plt) and phenazine-1-carboxylic acid (PCA). The ubiquitous RNA chaperone Hfq regulates bacterial virulence and stress tolerance through global posttranscriptional regulation. Here, we explored the molecular mechanism by which Hfq controls antibiotic biosynthesis in P. aeruginosa M18. The robust downregulation of Plt biosynthesis by Hfq was mediated exclusively by the posttranscriptional downregulation of the plt transcriptional activator PltR. Hfq posttranscriptionally repressed phzM expression and consequently reduced the conversion of PCA to pyocyanin. However, Hfq positively controlled the phz2 operon and PCA biosynthesis through both QscR-mediated transcriptional regulation at the promoter and an unknown regulation at the operator. Also, Hfq was shown to directly bind at the mRNA 5' untranslated leaders of pltR, qscR, and phzM. These three negatively regulated target genes of Hfq shared a similar secondary structure with a short single-stranded AU-rich spacer (a potential Hfq-binding motif) linking two stem-loops. Taken together, these results indicate that Hfq, potentially in collaboration with unknown small noncoding RNAs (sRNAs), tightly controls antibiotic biosynthesis through both direct posttranscriptional inhibition and indirect transcriptional regulation.
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48
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Someya T, Baba S, Fujimoto M, Kawai G, Kumasaka T, Nakamura K. Crystal structure of Hfq from Bacillus subtilis in complex with SELEX-derived RNA aptamer: insight into RNA-binding properties of bacterial Hfq. Nucleic Acids Res 2011; 40:1856-67. [PMID: 22053080 PMCID: PMC3287200 DOI: 10.1093/nar/gkr892] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Bacterial Hfq is a protein that plays an important role in the regulation of genes in cooperation with sRNAs. Escherichia coli Hfq (EcHfq) has two or more sites that bind RNA(s) including U-rich and/or the poly(A) tail of mRNA. However, functional and structural information about Bacillus subtilis Hfq (BsHfq) including the RNA sequences that specifically bind to it remain unknown. Here, we describe RNA aptamers including fragment (AG)(3)A that are recognized by BsHfq and crystal structures of the BsHfq-(AG)(3)A complex at 2.2 Å resolution. Mutational and structural studies revealed that the RNA fragment binds to the distal site, one of the two binding sites on Hfq, and identified amino acid residues that are critical for sequence-specific interactions between BsHfq and (AG)(3)A. In particular, R32 appears to interact with G bases in (AG)(3)A. Poly(A) also binds to the distal site of EcHfq, but the overall RNA structure and protein-RNA interaction patterns engaged in the R32 residues of BsHfq-(AG)(3)A differ from those of EcHfq-poly(A). These findings provide novel insight into how the Hfq homologue recognizes RNA.
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Affiliation(s)
- Tatsuhiko Someya
- Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba-shi, Ibaraki 305-8572, Japan.
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Abstract
Hfq is an RNA-binding protein that is common to diverse bacterial lineages and has key roles in the control of gene expression. By facilitating the pairing of small RNAs with their target mRNAs, Hfq affects the translation and turnover rates of specific transcripts and contributes to complex post-transcriptional networks. These functions of Hfq can be attributed to its ring-like oligomeric architecture, which presents two non-equivalent binding surfaces that are capable of multiple interactions with RNA molecules. Distant homologues of Hfq occur in archaea and eukaryotes, reflecting an ancient origin for the protein family and hinting at shared functions. In this Review, we describe the salient structural and functional features of Hfq and discuss possible mechanisms by which this protein can promote RNA interactions to catalyse specific and rapid regulatory responses in vivo.
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Affiliation(s)
- Jörg Vogel
- Institute for Molecular Infection Biology, University of Würzburg, Joseph-Schneider-Strasse 2, D-97080 Würzburg, Germany.
| | - Ben F. Luisi
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1GA, UK.
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50
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Chiang MK, Lu MC, Liu LC, Lin CT, Lai YC. Impact of Hfq on global gene expression and virulence in Klebsiella pneumoniae. PLoS One 2011; 6:e22248. [PMID: 21779404 PMCID: PMC3136514 DOI: 10.1371/journal.pone.0022248] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2011] [Accepted: 06/17/2011] [Indexed: 11/18/2022] Open
Abstract
Klebsiella pneumoniae is responsible for a wide range of clinical symptoms. How this bacterium adapts itself to ever-changing host milieu is still a mystery. Recently, small non-coding RNAs (sRNAs) have received considerable attention for their functions in fine-tuning gene expression at a post-transcriptional level to promote bacterial adaptation. Here we demonstrate that Hfq, an RNA-binding protein, which facilitates interactions between sRNAs and their mRNA targets, is critical for K. pneumoniae virulence. A K. pneumoniae mutant lacking hfq (Δhfq) failed to disseminate into extra-intestinal organs and was attenuated on induction of a systemic infection in a mouse model. The absence of Hfq was associated with alteration in composition of envelope proteins, increased production of capsular polysaccharides, and decreased resistance to H2O2, heat shock, and UV irradiation. Microarray-based transcriptome analyses revealed that 897 genes involved in numerous cellular processes were deregulated in the Δhfq strain. Interestingly, Hfq appeared to govern expression of many genes indirectly by affecting sigma factor RpoS and RpoE, since 19.5% (175/897) and 17.3% (155/897) of Hfq-dependent genes belong to the RpoE- and RpoS-regulon, respectively. These results indicate that Hfq regulates global gene expression at multiple levels to modulate the physiological fitness and virulence potential of K. pneumoniae.
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Affiliation(s)
- Ming-Ko Chiang
- Department of Life Science, National Chung-Cheng University, Chia-Yi, Taiwan
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