1
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Nandana V, Al-Husini N, Vaishnav A, Dilrangi KH, Schrader JM. Caulobacter crescentus RNase E condensation contributes to autoregulation and fitness. Mol Biol Cell 2024; 35:ar104. [PMID: 38865176 PMCID: PMC11321048 DOI: 10.1091/mbc.e23-12-0493] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2023] [Revised: 05/29/2024] [Accepted: 06/03/2024] [Indexed: 06/13/2024] Open
Abstract
RNase E is the most common RNA decay nuclease in bacteria, setting the global mRNA decay rate and scaffolding formation of the RNA degradosome complex and BR-bodies. To properly set the global mRNA decay rate, RNase E from Escherichia coli and neighboring γ-proteobacteria were found to autoregulate RNase E levels via the decay of its mRNA's 5' untranslated region (UTR). While the 5' UTR is absent from other groups of bacteria in the Rfam database, we identified that the α-proteobacterium Caulobacter crescentus RNase E contains a similar 5' UTR structure that promotes RNase E autoregulation. In both bacteria, the C-terminal intrinsically disordered region (IDR) of RNase E is required for proper autoregulation to occur, and this IDR is also necessary and sufficient for RNase E to phase-separate, generating BR-bodies. Using in vitro purified RNase E, we find that the IDR's ability to promote phase separation correlates with enhanced 5' UTR cleavage, suggesting that phase separation of RNase E with the 5' UTR enhances autoregulation. Finally, using growth competition experiments, we find that a strain capable of autoregulation rapidly outcompetes a strain with a 5' UTR mutation that cannot autoregulate, suggesting autoregulation promotes optimal cellular fitness.
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Affiliation(s)
- Vidhyadhar Nandana
- Department of Biological Sciences, Wayne State University, Detroit, MI 48202
| | - Nadra Al-Husini
- Department of Biological Sciences, Wayne State University, Detroit, MI 48202
| | - Arti Vaishnav
- Department of Biological Sciences, Wayne State University, Detroit, MI 48202
| | | | - Jared M. Schrader
- Department of Biological Sciences, Wayne State University, Detroit, MI 48202
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2
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Liu SJ, Lin GM, Yuan YQ, Chen W, Zhang JY, Zhang CC. A conserved protein inhibitor brings under check the activity of RNase E in cyanobacteria. Nucleic Acids Res 2024; 52:404-419. [PMID: 38000383 PMCID: PMC10783494 DOI: 10.1093/nar/gkad1094] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2023] [Revised: 09/21/2023] [Accepted: 10/31/2023] [Indexed: 11/26/2023] Open
Abstract
The bacterial ribonuclease RNase E plays a key role in RNA metabolism. Yet, with a large substrate spectrum and poor substrate specificity, its activity must be well controlled under different conditions. Only a few regulators of RNase E are known, limiting our understanding on posttranscriptional regulatory mechanisms in bacteria. Here we show that, RebA, a protein universally present in cyanobacteria, interacts with RNase E in the cyanobacterium Anabaena PCC 7120. Distinct from those known regulators of RNase E, RebA interacts with the catalytic region of RNase E, and suppresses the cleavage activities of RNase E for all tested substrates. Consistent with the inhibitory function of RebA on RNase E, depletion of RNase E and overproduction of RebA caused formation of elongated cells, whereas the absence of RebA and overproduction of RNase E resulted in a shorter-cell phenotype. We further showed that the morphological changes caused by altered levels of RNase E or RebA are dependent on their physical interaction. The action of RebA represents a new mechanism, potentially conserved in cyanobacteria, for RNase E regulation. Our findings provide insights into the regulation and the function of RNase E, and demonstrate the importance of balanced RNA metabolism in bacteria.
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Affiliation(s)
- Su-Juan Liu
- Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430070, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Gui-Ming Lin
- Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430070, China
| | - Yu-Qi Yuan
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, China
| | - Wenli Chen
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, China
| | - Ju-Yuan Zhang
- Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430070, China
| | - Cheng-Cai Zhang
- Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430070, China
- Key Laboratory of Lake and Watershed Science for Water Security, Chinese Academy of Sciences, Nanjing 210008, China
- Hubei Hongshan Laboratory, Wuhan 430070, China
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3
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Hoffmann UA, Lichtenberg E, Rogh SN, Bilger R, Reimann V, Heyl F, Backofen R, Steglich C, Hess WR, Wilde A. The role of the 5' sensing function of ribonuclease E in cyanobacteria. RNA Biol 2024; 21:1-18. [PMID: 38469716 PMCID: PMC10939160 DOI: 10.1080/15476286.2024.2328438] [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] [Accepted: 03/05/2024] [Indexed: 03/13/2024] Open
Abstract
RNA degradation is critical for synchronising gene expression with changing conditions in prokaryotic and eukaryotic organisms. In bacteria, the preference of the central ribonucleases RNase E, RNase J and RNase Y for 5'-monophosphorylated RNAs is considered important for RNA degradation. For RNase E, the underlying mechanism is termed 5' sensing, contrasting to the alternative 'direct entry' mode, which is independent of monophosphorylated 5' ends. Cyanobacteria, such as Synechocystis sp. PCC 6803 (Synechocystis), encode RNase E and RNase J homologues. Here, we constructed a Synechocystis strain lacking the 5' sensing function of RNase E and mapped on a transcriptome-wide level 283 5'-sensing-dependent cleavage sites. These included so far unknown targets such as mRNAs encoding proteins related to energy metabolism and carbon fixation. The 5' sensing function of cyanobacterial RNase E is important for the maturation of rRNA and several tRNAs, including tRNAGluUUC. This tRNA activates glutamate for tetrapyrrole biosynthesis in plant chloroplasts and in most prokaryotes. Furthermore, we found that increased RNase activities lead to a higher copy number of the major Synechocystis plasmids pSYSA and pSYSM. These results provide a first step towards understanding the importance of the different target mechanisms of RNase E outside Escherichia coli.
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Affiliation(s)
- Ute A. Hoffmann
- Molecular Genetics of Prokaryotes, Institute of Biology III, University of Freiburg, Freiburg, Germany
- School of Engineering Sciences in Chemistry, Biotechnology and Health, Science for Life Laboratory, KTH - Royal Institute of Technology, Stockholm, Sweden
| | - Elisabeth Lichtenberg
- Molecular Genetics of Prokaryotes, Institute of Biology III, University of Freiburg, Freiburg, Germany
| | - Said N. Rogh
- Molecular Genetics of Prokaryotes, Institute of Biology III, University of Freiburg, Freiburg, Germany
| | - Raphael Bilger
- Genetics and Experimental Bioinformatics, Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Viktoria Reimann
- Genetics and Experimental Bioinformatics, Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Florian Heyl
- Bioinformatics Group, Department of Computer Science, University of Freiburg, Freiburg, Germany
| | - Rolf Backofen
- Bioinformatics Group, Department of Computer Science, University of Freiburg, Freiburg, Germany
- Signalling Research Centres BIOSS and CIBSS, University of Freiburg, Freiburg, Germany
| | - Claudia Steglich
- Genetics and Experimental Bioinformatics, Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Wolfgang R. Hess
- Genetics and Experimental Bioinformatics, Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Annegret Wilde
- Molecular Genetics of Prokaryotes, Institute of Biology III, University of Freiburg, Freiburg, Germany
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4
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Nandana V, Al-Husini N, Vaishnav A, Dilrangi KH, Schrader JM. Caulobacter crescentus RNase E condensation contributes to autoregulation and fitness. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.15.571756. [PMID: 38168245 PMCID: PMC10760160 DOI: 10.1101/2023.12.15.571756] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2024]
Abstract
RNase E is the most common RNA decay nuclease in bacteria, setting the global mRNA decay rate and scaffolding formation of the RNA degradosome complex and BR-bodies. To properly set the global mRNA decay rate, RNase E from Escherichia coli and neighboring γ-proteobacteria were found to autoregulate RNase E levels via the decay of its mRNA's 5' UTR. While the 5' UTR is absent from other groups of bacteria in the Rfam database, we identified that the α-proteobacterium Caulobacter crescentus RNase E contains a similar 5' UTR structure that promotes RNase E autoregulation. In both bacteria, the C-terminal IDR of RNase E is required for proper autoregulation to occur, and this IDR is also necessary and sufficient for RNase E to phase-separate, generating BR-bodies. Using in vitro purified RNase E, we find that the IDR's ability to promote phase-separation correlates with enhanced 5' UTR cleavage, suggesting that phase-separation of RNase E with the 5' UTR enhances autoregulation. Finally, using growth competition experiments we find that a strain capable of autoregulation rapidly outcompetes a strain with a 5' UTR mutation that cannot autoregulate, suggesting autoregulation promotes optimal cellular fitness.
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Affiliation(s)
- Vidhyadhar Nandana
- Department of Biological Sciences, Wayne State University, Detroit, MI 48202
| | - Nadra Al-Husini
- Department of Biological Sciences, Wayne State University, Detroit, MI 48202
| | | | | | - Jared M. Schrader
- Department of Biological Sciences, Wayne State University, Detroit, MI 48202
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5
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Watanabe S, Stazic D, Georg J, Ohtake S, Sakamaki Y, Numakura M, Asayama M, Chibazakura T, Wilde A, Steglich C, Hess WR. Regulation of RNase E during the UV stress response in the cyanobacterium Synechocystis sp. PCC 6803. MLIFE 2023; 2:43-57. [PMID: 38818332 PMCID: PMC10989929 DOI: 10.1002/mlf2.12056] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/01/2022] [Revised: 12/07/2022] [Accepted: 12/15/2022] [Indexed: 06/01/2024]
Abstract
Endoribonucleases govern the maturation and degradation of RNA and are indispensable in the posttranscriptional regulation of gene expression. A key endoribonuclease in Gram-negative bacteria is RNase E. To ensure an appropriate supply of RNase E, some bacteria, such as Escherichia coli, feedback-regulate RNase E expression via the rne 5'-untranslated region (5' UTR) in cis. However, the mechanisms involved in the control of RNase E in other bacteria largely remain unknown. Cyanobacteria rely on solar light as an energy source for photosynthesis, despite the inherent ultraviolet (UV) irradiation. In this study, we first investigated globally the changes in gene expression in the cyanobacterium Synechocystis sp. PCC 6803 after a brief exposure to UV. Among the 407 responding genes 2 h after UV exposure was a prominent upregulation of rne mRNA level. Moreover, the enzymatic activity of RNase E rapidly increased as well, although the protein stability decreased. This unique response was underpinned by the increased accumulation of full-length rne mRNA caused by the stabilization of its 5' UTR and suppression of premature transcriptional termination, but not by an increased transcription rate. Mapping of RNA 3' ends and in vitro cleavage assays revealed that RNase E cleaves within a stretch of six consecutive uridine residues within the rne 5' UTR, indicating autoregulation. These observations suggest that RNase E in cyanobacteria contributes to reshaping the transcriptome during the UV stress response and that its required activity level is secured at the RNA level despite the enhanced turnover of the protein.
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Affiliation(s)
- Satoru Watanabe
- Faculty of Biology, Genetics and Experimental BioinformaticsUniversity of FreiburgFreiburgGermany
| | - Damir Stazic
- Department of BioscienceTokyo University of AgricultureSetagaya‐kuTokyoJapan
- Present address:
NexxiotPrime Tower (Hardstrasse 201)ZurichSwitzerland
| | - Jens Georg
- Department of BioscienceTokyo University of AgricultureSetagaya‐kuTokyoJapan
| | - Shota Ohtake
- Faculty of Biology, Genetics and Experimental BioinformaticsUniversity of FreiburgFreiburgGermany
| | - Yutaka Sakamaki
- Faculty of Biology, Genetics and Experimental BioinformaticsUniversity of FreiburgFreiburgGermany
| | - Megumi Numakura
- Faculty of Biology, Genetics and Experimental BioinformaticsUniversity of FreiburgFreiburgGermany
| | - Munehiko Asayama
- School of Agriculture, Molecular GeneticsIbaraki UniversityIbarakiJapan
| | - Taku Chibazakura
- Faculty of Biology, Genetics and Experimental BioinformaticsUniversity of FreiburgFreiburgGermany
| | - Annegret Wilde
- Faculty of Biology, Molecular GeneticsUniversity of FreiburgFreiburgGermany
| | - Claudia Steglich
- Department of BioscienceTokyo University of AgricultureSetagaya‐kuTokyoJapan
| | - Wolfgang R. Hess
- Department of BioscienceTokyo University of AgricultureSetagaya‐kuTokyoJapan
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6
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Relaxed Cleavage Specificity of Hyperactive Variants of Escherichia coli RNase E on RNA I. J Microbiol 2023; 61:211-220. [PMID: 36814003 DOI: 10.1007/s12275-023-00013-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Revised: 12/26/2022] [Accepted: 12/27/2022] [Indexed: 02/24/2023]
Abstract
RNase E is an essential enzyme in Escherichia coli. The cleavage site of this single-stranded specific endoribonuclease is well-characterized in many RNA substrates. Here, we report that the upregulation of RNase E cleavage activity by a mutation that affects either RNA binding (Q36R) or enzyme multimerization (E429G) was accompanied by relaxed cleavage specificity. Both mutations led to enhanced RNase E cleavage in RNA I, an antisense RNA of ColE1-type plasmid replication, at a major site and other cryptic sites. Expression of a truncated RNA I with a major RNase E cleavage site deletion at the 5'-end (RNA I-5) resulted in an approximately twofold increase in the steady-state levels of RNA I-5 and the copy number of ColE1-type plasmid in E. coli cells expressing wild-type or variant RNase E compared to those expressing RNA I. These results indicate that RNA I-5 does not efficiently function as an antisense RNA despite having a triphosphate group at the 5'-end, which protects the RNA from ribonuclease attack. Our study suggests that increased cleavage rates of RNase E lead to relaxed cleavage specificity on RNA I and the inability of the cleavage product of RNA I as an antisense regulator in vivo does not stem from its instability by having 5'-monophosphorylated end.
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7
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Clarke JE, Sabharwal K, Kime L, McDowall KJ. The recognition of structured elements by a conserved groove distant from domains associated with catalysis is an essential determinant of RNase E. Nucleic Acids Res 2023; 51:365-379. [PMID: 36594161 PMCID: PMC9841416 DOI: 10.1093/nar/gkac1228] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Revised: 11/11/2022] [Accepted: 12/08/2022] [Indexed: 01/04/2023] Open
Abstract
RNase E is an endoribonuclease found in many bacteria, including important human pathogens. Within Escherichia coli, it has been shown to have a major role in both the maturation of all classes of RNA involved in translation and the initiation of mRNA degradation. Thus, knowledge of the major determinants of RNase E cleavage is central to our understanding and manipulation of bacterial gene expression. We show here that the binding of RNase E to structured RNA elements is crucial for the processing of tRNA, can activate catalysis and may be important in mRNA degradation. The recognition of structured elements by RNase E is mediated by a recently discovered groove that is distant from the domains associated with catalysis. The functioning of this groove is shown here to be essential for E. coli cell viability and may represent a key point of evolutionary divergence from the paralogous RNase G family, which we show lack amino acid residues conserved within the RNA-binding groove of members of the RNase E family. Overall, this work provides new insights into the recognition and cleavage of RNA by RNase E and provides further understanding of the basis of RNase E essentiality in E. coli.
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Affiliation(s)
| | | | - Louise Kime
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK
| | - Kenneth J McDowall
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK
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8
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Lambrecht SJ, Stappert N, Sommer F, Schroda M, Steglich C. A Cyanophage MarR-Type Transcription Factor Regulates Host RNase E Expression during Infection. Microorganisms 2022; 10:2245. [PMID: 36422315 PMCID: PMC9692554 DOI: 10.3390/microorganisms10112245] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Revised: 11/04/2022] [Accepted: 11/10/2022] [Indexed: 06/30/2024] Open
Abstract
The marine picocyanobacterium Prochlorococcus contributes significantly to global primary production, and its abundance and diversity is shaped in part by viral infection. Here, we identified a cyanophage-encoded MarR-type transcription factor that induces the gene expression of host Prochlorococcus MED4 endoribonuclease (RNase) E during phage infection. The increase in rne transcript levels relies on the phage (p)MarR-mediated activation of an alternative promoter that gives rise to a truncated yet enzymatically fully functional RNase E isoform. In this study, we demonstrate that pMarR binds to an atypical activator site downstream of the transcriptional start site and that binding is enhanced in the presence of Ca2+ ions. Furthermore, we show that dimeric pMarR interacts with the α subunit of RNA polymerase, and we identified amino acid residues S66, R67, and G106, which are important for Ca2+ binding, DNA binding, and dimerization of pMarR, respectively.
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Affiliation(s)
- S. Joke Lambrecht
- Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany
- Medical Faculty, Medical Center, Institute for Surgical Pathology, University of Freiburg, 79106 Freiburg, Germany
| | - Nils Stappert
- Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany
| | - Frederik Sommer
- Molecular Biotechnology & Systems Biology, TU Kaiserslautern, 67663 Kaiserslautern, Germany
| | - Michael Schroda
- Molecular Biotechnology & Systems Biology, TU Kaiserslautern, 67663 Kaiserslautern, Germany
| | - Claudia Steglich
- Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany
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9
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Mohanty BK, Kushner SR. Regulation of mRNA decay in E. coli. Crit Rev Biochem Mol Biol 2022; 57:48-72. [PMID: 34547957 PMCID: PMC9973670 DOI: 10.1080/10409238.2021.1968784] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Revised: 08/03/2021] [Accepted: 08/12/2021] [Indexed: 10/20/2022]
Abstract
Detailed studies of the Gram-negative model bacterium, Escherichia coli, have demonstrated that post-transcriptional events exert important and possibly greater control over gene regulation than transcription initiation or effective translation. Thus, over the past 30 years, considerable effort has been invested in understanding the pathways of mRNA turnover in E. coli. Although it is assumed that most of the ribonucleases and accessory proteins involved in mRNA decay have been identified, our understanding of the regulation of mRNA decay is still incomplete. Furthermore, the vast majority of the studies on mRNA decay have been conducted on exponentially growing cells. Thus, the mechanism of mRNA decay as currently outlined may not accurately reflect what happens when cells find themselves under a variety of stress conditions, such as, nutrient starvation, changes in pH and temperature, as well as a host of others. While the cellular machinery for degradation is relatively constant over a wide range of conditions, intracellular levels of specific ribonucleases can vary depending on the growth conditions. Substrate competition will also modulate ribonucleolytic activity. Post-transcriptional modifications of transcripts by polyadenylating enzymes may favor a specific ribonuclease activity. Interactions with small regulatory RNAs and RNA binding proteins add additional complexities to mRNA functionality and stability. Since many of the ribonucleases are found at the inner membrane, the physical location of a transcript may help determine its half-life. Here we discuss the properties and role of the enzymes involved in mRNA decay as well as the multiple factors that may affect mRNA decay under various in vivo conditions.
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Affiliation(s)
| | - Sidney R. Kushner
- Department of Genetics, University of Georgia, Athens GA 30602
- Department of Microbiology, University of Georgia, Athens GA 30602
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10
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Hoffmann UA, Heyl F, Rogh SN, Wallner T, Backofen R, Hess WR, Steglich C, Wilde A. Transcriptome-wide in vivo mapping of cleavage sites for the compact cyanobacterial ribonuclease E reveals insights into its function and substrate recognition. Nucleic Acids Res 2021; 49:13075-13091. [PMID: 34871439 PMCID: PMC8682795 DOI: 10.1093/nar/gkab1161] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Revised: 10/26/2021] [Accepted: 11/16/2021] [Indexed: 12/13/2022] Open
Abstract
Ribonucleases are crucial enzymes in RNA metabolism and post-transcriptional regulatory processes in bacteria. Cyanobacteria encode the two essential ribonucleases RNase E and RNase J. Cyanobacterial RNase E is shorter than homologues in other groups of bacteria and lacks both the chloroplast-specific N-terminal extension as well as the C-terminal domain typical for RNase E of enterobacteria. In order to investigate the function of RNase E in the model cyanobacterium Synechocystis sp. PCC 6803, we engineered a temperature-sensitive RNase E mutant by introducing two site-specific mutations, I65F and the spontaneously occurred V94A. This enabled us to perform RNA-seq after the transient inactivation of RNase E by a temperature shift (TIER-seq) and to map 1472 RNase-E-dependent cleavage sites. We inferred a dominating cleavage signature consisting of an adenine at the -3 and a uridine at the +2 position within a single-stranded segment of the RNA. The data identified mRNAs likely regulated jointly by RNase E and an sRNA and potential 3' end-derived sRNAs. Our findings substantiate the pivotal role of RNase E in post-transcriptional regulation and suggest the redundant or concerted action of RNase E and RNase J in cyanobacteria.
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Affiliation(s)
- Ute A Hoffmann
- Molecular Genetics of Prokaryotes, Institute of Biology III, University of Freiburg, 79104 Freiburg, Germany
| | - Florian Heyl
- Bioinformatics Group, Department of Computer Science, University of Freiburg, 79110 Freiburg, Germany
| | - Said N Rogh
- Molecular Genetics of Prokaryotes, Institute of Biology III, University of Freiburg, 79104 Freiburg, Germany
| | - Thomas Wallner
- Molecular Genetics of Prokaryotes, Institute of Biology III, University of Freiburg, 79104 Freiburg, Germany
| | - Rolf Backofen
- Bioinformatics Group, Department of Computer Science, University of Freiburg, 79110 Freiburg, Germany.,Signalling Research Centres BIOSS and CIBSS, University of Freiburg, 79104 Freiburg, Germany
| | - Wolfgang R Hess
- Genetics and Experimental Bioinformatics, Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany
| | - Claudia Steglich
- Genetics and Experimental Bioinformatics, Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany
| | - Annegret Wilde
- Molecular Genetics of Prokaryotes, Institute of Biology III, University of Freiburg, 79104 Freiburg, Germany
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11
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Tailoring the evolution of BL21(DE3) uncovers a key role for RNA stability in gene expression toxicity. Commun Biol 2021; 4:963. [PMID: 34385596 PMCID: PMC8361080 DOI: 10.1038/s42003-021-02493-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Accepted: 07/20/2021] [Indexed: 02/07/2023] Open
Abstract
Gene expression toxicity is an important biological phenomenon and a major bottleneck in biotechnology. Escherichia coli BL21(DE3) is the most popular choice for recombinant protein production, and various derivatives have been evolved or engineered to facilitate improved yield and tolerance to toxic genes. However, previous efforts to evolve BL21, such as the Walker strains C41 and C43, resulted only in decreased expression strength of the T7 system. This reveals little about the mechanisms at play and constitutes only marginal progress towards a generally higher producing cell factory. Here, we restrict the solution space for BL21(DE3) to evolve tolerance and isolate a mutant strain Evo21(DE3) with a truncation in the essential RNase E. This suggests that RNA stability plays a central role in gene expression toxicity. The evolved rne truncation is similar to a mutation previously engineered into the commercially available BL21Star(DE3), which challenges the existing assumption that this strain is unsuitable for expressing toxic proteins. We isolated another dominant mutation in a presumed substrate binding site of RNase E that improves protein production further when provided as an auxiliary plasmid. This makes it easy to improve other BL21 variants and points to RNases as prime targets for cell factory optimisation.
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12
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Jaso-Vera ME, Domínguez-Malfavón L, Curiel-Quesada E, García-Mena J. Dynamics of the canonical RNA degradosome components during glucose stress. Biochimie 2021; 187:67-74. [PMID: 34022290 DOI: 10.1016/j.biochi.2021.05.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Revised: 04/21/2021] [Accepted: 05/12/2021] [Indexed: 11/19/2022]
Abstract
The RNA Degradosome (RNAD) is a multi-enzyme complex, which performs important functions in post-transcriptional regulation in Escherichia coli with the assistance of regulatory sRNAs and the RNA chaperone Hfq. Although the interaction of the canonical RNAD components with RNase E has been extensively studied, the dynamic nature of the interactions in vivo remains largely unknown. In this work, we explored the rearrangements upon glucose stress using fluorescence energy transfer (hetero-FRET). Results revealed differences in the proximity of the canonical components with 1% (55.5 mM) glucose concentration, with the helicase RhlB and the glycolytic enzyme Enolase exhibiting the largest changes to the C-terminus of RNase E, followed by PNPase. We quantified ptsG mRNA decay and SgrS sRNA synthesis as they mediate bacterial adaptation to glucose stress conditions. We propose that once the mRNA degradation is completed, the RhlB, Enolase and PNPase decrease their proximity to the C-terminus of RNase E. Based on the results, we present a model where the canonical components of the RNAD coalesce when the bacteria is under glucose-6-phosphate stress and associate it with RNA decay. Our results demonstrate that FRET is a helpful tool to study conformational rearrangements in enzymatic complexes in bacteria in vivo.
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Affiliation(s)
- Marcos Emmanuel Jaso-Vera
- Departamento de Genética y Biología Molecular, Cinvestav, Unidad Zacatenco, Ciudad de México, 07360, Mexico
| | - Lilianha Domínguez-Malfavón
- Department of Biotechnology, Universidad Autónoma Metropolitana (Unidad Iztapalapa), Ciudad de México, 09340, Mexico
| | - Everardo Curiel-Quesada
- Departamento de Bioquímica, Escuela Nacional de Ciencias Biológicas del Instituto Politécnico Nacional (ENCB-IPN), Ciudad de México, 11340, Mexico
| | - Jaime García-Mena
- Departamento de Genética y Biología Molecular, Cinvestav, Unidad Zacatenco, Ciudad de México, 07360, Mexico.
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13
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Lee J, Lee M, Lee K. Trans-acting regulators of ribonuclease activity. J Microbiol 2021; 59:341-359. [PMID: 33779951 DOI: 10.1007/s12275-021-0650-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Revised: 12/28/2020] [Accepted: 12/28/2020] [Indexed: 12/16/2022]
Abstract
RNA metabolism needs to be tightly regulated in response to changes in cellular physiology. Ribonucleases (RNases) play an essential role in almost all aspects of RNA metabolism, including processing, degradation, and recycling of RNA molecules. Thus, living systems have evolved to regulate RNase activity at multiple levels, including transcription, post-transcription, post-translation, and cellular localization. In addition, various trans-acting regulators of RNase activity have been discovered in recent years. This review focuses on the physiological roles and underlying mechanisms of trans-acting regulators of RNase activity.
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Affiliation(s)
- Jaejin Lee
- Department of Life Science, Chung-Ang University, Seoul, 06974, Republic of Korea
| | - Minho Lee
- Department of Life Science, Chung-Ang University, Seoul, 06974, Republic of Korea.
| | - Kangseok Lee
- Department of Life Science, Chung-Ang University, Seoul, 06974, Republic of Korea.
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14
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Lee J, Lee M, Lee K. Trans-acting regulators of ribonuclease activity. J Microbiol 2021:10.1007/s12275-021-0650-3. [PMID: 33565052 DOI: 10.1007/s12275-021-0650-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Revised: 12/28/2020] [Accepted: 12/28/2020] [Indexed: 11/29/2022]
Abstract
RNA metabolism needs to be tightly regulated in response to changes in cellular physiology. Ribonucleases (RNases) play an essential role in almost all aspects of RNA metabolism, including processing, degradation, and recycling of RNA molecules. Thus, living systems have evolved to regulate RNase activity at multiple levels, including transcription, post-transcription, post-translation, and cellular localization. In addition, various trans-acting regulators of RNase activity have been discovered in recent years. This review focuses on the physiological roles and underlying mechanisms of trans-acting regulators of RNase activity.
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Affiliation(s)
- Jaejin Lee
- Department of Life Science, Chung-Ang University, Seoul, 06974, Republic of Korea
| | - Minho Lee
- Department of Life Science, Chung-Ang University, Seoul, 06974, Republic of Korea.
| | - Kangseok Lee
- Department of Life Science, Chung-Ang University, Seoul, 06974, Republic of Korea.
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15
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Lee M, Ryu M, Joo M, Seo YJ, Lee J, Kim HM, Shin E, Yeom JH, Kim YH, Bae J, Lee K. Endoribonuclease-mediated control of hns mRNA stability constitutes a key regulatory pathway for Salmonella Typhimurium pathogenicity island 1 expression. PLoS Pathog 2021; 17:e1009263. [PMID: 33524062 PMCID: PMC7877770 DOI: 10.1371/journal.ppat.1009263] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Revised: 02/11/2021] [Accepted: 01/01/2021] [Indexed: 01/04/2023] Open
Abstract
Bacteria utilize endoribonuclease-mediated RNA processing and decay to rapidly adapt to environmental changes. Here, we report that the modulation of hns mRNA stability by the endoribonuclease RNase G plays a key role in Salmonella Typhimurium pathogenicity. We found that RNase G determines the half-life of hns mRNA by cleaving its 5′ untranslated region and that altering its cleavage sites by genome editing stabilizes hns mRNA, thus decreasing S. Typhimurium virulence in mice. Under anaerobic conditions, the FNR-mediated transcriptional repression of rnc encoding RNase III, which degrades rng mRNA, and simultaneous induction of rng transcription resulted in rapid hns mRNA degradation, leading to the derepression of genes involved in the Salmonella pathogenicity island 1 (SPI-1) type III secretion system (T3SS). Together, our findings show that RNase III and RNase G levels-mediated control of hns mRNA abundance acts as a regulatory pathway upstream of a complex feed-forward loop for SPI-1 expression. Recent studies have shown that pathogenic bacteria with ribonuclease mutations display attenuated virulence, impaired mobility, and reduced proliferation in host cells. However, the molecular mechanisms underlying ribonuclease-associated pathogenesis have not yet been characterised. Here, we provide strong experimental evidence that the coordinated modulation of endoribonuclease activity constitutes an additional regulatory layer upstream of a complex feed-forward loop controlling global regulatory systems in the Salmonella pathogenicity island 1 (SPI-1) type III secretion system (T3SS). In addition, we showed that this regulatory pathway plays a key role in the virulence of S. Typhimurium in the host. Thus, our study improves the understanding of the mechanisms through which bacterial pathogens sense the host environment and respond precisely by expressing gene products required for adaptation to that particular niche.
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Affiliation(s)
- Minho Lee
- Department of Life Science, Chung-Ang University, Dongjak-Gu, Seoul, Republic of Korea
| | - Minkyung Ryu
- Department of Life Science, Chung-Ang University, Dongjak-Gu, Seoul, Republic of Korea
| | - Minju Joo
- Department of Life Science, Chung-Ang University, Dongjak-Gu, Seoul, Republic of Korea
| | - Young-Jin Seo
- Department of Life Science, Chung-Ang University, Dongjak-Gu, Seoul, Republic of Korea
| | - Jaejin Lee
- Department of Life Science, Chung-Ang University, Dongjak-Gu, Seoul, Republic of Korea
| | - Hong-Man Kim
- Department of Life Science, Chung-Ang University, Dongjak-Gu, Seoul, Republic of Korea
| | - Eunkyoung Shin
- Department of Pharmacy, Chung-Ang University, Dongjak-Gu, Seoul, Republic of Korea
| | - Ji-Hyun Yeom
- Department of Life Science, Chung-Ang University, Dongjak-Gu, Seoul, Republic of Korea
| | - Yong-Hak Kim
- Department of Microbiology, Daegu Catholic University School of Medicine, Daegu, Republic of Korea
- * E-mail: (Y-HK); (JB); (KL)
| | - Jeehyeon Bae
- Department of Pharmacy, Chung-Ang University, Dongjak-Gu, Seoul, Republic of Korea
- * E-mail: (Y-HK); (JB); (KL)
| | - Kangseok Lee
- Department of Life Science, Chung-Ang University, Dongjak-Gu, Seoul, Republic of Korea
- * E-mail: (Y-HK); (JB); (KL)
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16
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Substrate-dependent effects of quaternary structure on RNase E activity. Genes Dev 2021; 35:286-299. [PMID: 33446571 PMCID: PMC7849360 DOI: 10.1101/gad.335828.119] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2019] [Accepted: 12/15/2020] [Indexed: 11/25/2022]
Abstract
RNase E is an essential, multifunctional ribonuclease encoded in E. coli by the rne gene. Structural analysis indicates that the ribonucleolytic activity of this enzyme is conferred by rne-encoded polypeptide chains that (1) dimerize to form a catalytic site at the protein-protein interface, and (2) multimerize further to generate a tetrameric quaternary structure consisting of two dimerized Rne-peptide chains. We identify here a mutation in the Rne protein's catalytic region (E429G), as well as a bacterial cell wall peptidoglycan hydrolase (Amidase C [AmiC]), that selectively affect the specific activity of the RNase E enzyme on long RNA substrates, but not on short synthetic oligonucleotides, by enhancing enzyme multimerization. Unlike the increase in specific activity that accompanies concentration-induced multimerization, enhanced multimerization associated with either the E429G mutation or interaction of the Rne protein with AmiC is independent of the substrate's 5' terminus phosphorylation state. Our findings reveal a previously unsuspected substrate length-dependent regulatory role for RNase E quaternary structure and identify cis-acting and trans-acting factors that mediate such regulation.
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17
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Etienne TA, Cocaign-Bousquet M, Ropers D. Competitive effects in bacterial mRNA decay. J Theor Biol 2020; 504:110333. [PMID: 32615126 DOI: 10.1016/j.jtbi.2020.110333] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Revised: 05/08/2020] [Accepted: 05/12/2020] [Indexed: 12/15/2022]
Abstract
In living organisms, the same enzyme catalyses the degradation of thousands of different mRNAs, but the possible influence of competing substrates has been largely ignored so far. We develop a simple mechanistic model of the coupled degradation of all cell mRNAs using the total quasi-steady-state approximation of the Michaelis-Menten framework. Numerical simulations of the model using carefully chosen parameters and analyses of rate sensitivity coefficients show how substrate competition alters mRNA decay. The model predictions reproduce and explain a number of experimental observations on mRNA decay following transcription arrest, such as delays before the onset of degradation, the occurrence of variable degradation profiles with increased non linearities and the negative correlation between mRNA half-life and concentration. The competition acts at different levels, through the initial concentration of cell mRNAs and by modifying the enzyme affinity for its targets. The consequence is a global slow down of mRNA decay due to enzyme titration and the amplification of its apparent affinity. Competition happens to stabilize weakly affine mRNAs and to destabilize the most affine ones. We believe that this mechanistic model is an interesting alternative to the exponential models commonly used for the determination of mRNA half-lives. It allows analysing regulatory mechanisms of mRNA degradation and its predictions are directly comparable to experimental data.
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Affiliation(s)
- Thibault A Etienne
- TBI, Université de Toulouse, CNRS, INRA, INSA, Toulouse, France; Univ. Grenoble Alpes, Inria, 38000 Grenoble, France
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18
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Ojha S, Jain C. Dual-level autoregulation of the E. coli DeaD RNA helicase via mRNA stability and Rho-dependent transcription termination. RNA (NEW YORK, N.Y.) 2020; 26:1160-1169. [PMID: 32414857 PMCID: PMC7430678 DOI: 10.1261/rna.074112.119] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Accepted: 05/11/2020] [Indexed: 06/11/2023]
Abstract
DEAD-box proteins (DBPs) are RNA remodeling factors associated with RNA helicase activity that are found in nearly all organisms. Despite extensive studies on the mechanisms used by DBPs to regulate RNA function, very little is known about how DBPs themselves are regulated. In this work, we have analyzed the expression and regulation of DeaD/CsdA, the largest of the DBPs in Escherichia coli (E. coli). We show that deaD transcription initiates 838 nt upstream of the start of the coding region. We have also found that DeaD is autoregulated through a negative feedback mechanism that operates both at the level of deaD mRNA stability and Rho-dependent transcription termination, and this regulation is dependent upon its mRNA 5' untranslated region (5' UTR). These findings suggest that DeaD might be regulating the conformation of its own mRNA through its RNA helicase activity to facilitate ribonuclease and Rho access to its 5' UTR.
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Affiliation(s)
- Sandeep Ojha
- Department of Biochemistry and Molecular Biology, University of Miami Miller School of Medicine, Miami, Florida 33136, USA
| | - Chaitanya Jain
- Department of Biochemistry and Molecular Biology, University of Miami Miller School of Medicine, Miami, Florida 33136, USA
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19
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Ali N, Gowrishankar J. Cross-subunit catalysis and a new phenomenon of recessive resurrection in Escherichia coli RNase E. Nucleic Acids Res 2020; 48:847-861. [PMID: 31802130 PMCID: PMC6954427 DOI: 10.1093/nar/gkz1152] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Revised: 11/21/2019] [Accepted: 11/26/2019] [Indexed: 12/13/2022] Open
Abstract
RNase E is a 472-kDa homo-tetrameric essential endoribonuclease involved in RNA processing and turnover in Escherichia coli. In its N-terminal half (NTH) is the catalytic active site, as also a substrate 5′-sensor pocket that renders enzyme activity maximal on 5′-monophosphorylated RNAs. The protein's non-catalytic C-terminal half (CTH) harbours RNA-binding motifs and serves as scaffold for a multiprotein degradosome complex, but is dispensable for viability. Here, we provide evidence that a full-length hetero-tetramer, composed of a mixture of wild-type and (recessive lethal) active-site mutant subunits, exhibits identical activity in vivo as the wild-type homo-tetramer itself (‘recessive resurrection’). When all of the cognate polypeptides lacked the CTH, the active-site mutant subunits were dominant negative. A pair of C-terminally truncated polypeptides, which were individually inactive because of additional mutations in their active site and 5′-sensor pocket respectively, exhibited catalytic function in combination, both in vivo and in vitro (i.e. intragenic or allelic complementation). Our results indicate that adjacent subunits within an oligomer are separately responsible for 5′-sensing and cleavage, and that RNA binding facilitates oligomerization. We propose also that the CTH mediates a rate-determining initial step for enzyme function, which is likely the binding and channelling of substrate for NTH’s endonucleolytic action.
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Affiliation(s)
- Nida Ali
- Laboratory of Bacterial Genetics, Centre for DNA Fingerprinting and Diagnostics, Hyderabad 500039, India.,Graduate Studies, Manipal Academy of Higher Education, Manipal 576104, India
| | - Jayaraman Gowrishankar
- Laboratory of Bacterial Genetics, Centre for DNA Fingerprinting and Diagnostics, Hyderabad 500039, India
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20
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Kusmierek M, Hoßmann J, Witte R, Opitz W, Vollmer I, Volk M, Heroven AK, Wolf-Watz H, Dersch P. A bacterial secreted translocator hijacks riboregulators to control type III secretion in response to host cell contact. PLoS Pathog 2019; 15:e1007813. [PMID: 31173606 PMCID: PMC6583979 DOI: 10.1371/journal.ppat.1007813] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Revised: 06/19/2019] [Accepted: 05/02/2019] [Indexed: 02/05/2023] Open
Abstract
Numerous Gram-negative pathogens use a Type III Secretion System (T3SS) to promote virulence by injecting effector proteins into targeted host cells, which subvert host cell processes. Expression of T3SS and the effectors is triggered upon host cell contact, but the underlying mechanism is poorly understood. Here, we report a novel strategy of Yersinia pseudotuberculosis in which this pathogen uses a secreted T3SS translocator protein (YopD) to control global RNA regulators. Secretion of the YopD translocator upon host cell contact increases the ratio of post-transcriptional regulator CsrA to its antagonistic small RNAs CsrB and CsrC and reduces the degradosome components PNPase and RNase E levels. This substantially elevates the amount of the common transcriptional activator (LcrF) of T3SS/Yop effector genes and triggers the synthesis of associated virulence-relevant traits. The observed hijacking of global riboregulators allows the pathogen to coordinate virulence factor expression and also readjusts its physiological response upon host cell contact.
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Affiliation(s)
- Maria Kusmierek
- Department of Molecular Infection Biology, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Jörn Hoßmann
- Department of Molecular Infection Biology, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Rebekka Witte
- Department of Molecular Infection Biology, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Wiebke Opitz
- Department of Molecular Infection Biology, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Ines Vollmer
- Department of Molecular Infection Biology, Helmholtz Centre for Infection Research, Braunschweig, Germany
- Institute for Infectiology, University of Münster, Germany
| | - Marcel Volk
- Department of Molecular Infection Biology, Helmholtz Centre for Infection Research, Braunschweig, Germany
- Institute for Infectiology, University of Münster, Germany
| | - Ann Kathrin Heroven
- Department of Molecular Infection Biology, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Hans Wolf-Watz
- Department of Molecular Biology, Umea University, Sweden
| | - Petra Dersch
- Department of Molecular Infection Biology, Helmholtz Centre for Infection Research, Braunschweig, Germany
- Institute for Infectiology, University of Münster, Germany
- * E-mail:
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21
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Bechhofer DH, Deutscher MP. Bacterial ribonucleases and their roles in RNA metabolism. Crit Rev Biochem Mol Biol 2019; 54:242-300. [PMID: 31464530 PMCID: PMC6776250 DOI: 10.1080/10409238.2019.1651816] [Citation(s) in RCA: 109] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Revised: 07/22/2019] [Accepted: 07/31/2019] [Indexed: 12/16/2022]
Abstract
Ribonucleases (RNases) are mediators in most reactions of RNA metabolism. In recent years, there has been a surge of new information about RNases and the roles they play in cell physiology. In this review, a detailed description of bacterial RNases is presented, focusing primarily on those from Escherichia coli and Bacillus subtilis, the model Gram-negative and Gram-positive organisms, from which most of our current knowledge has been derived. Information from other organisms is also included, where relevant. In an extensive catalog of the known bacterial RNases, their structure, mechanism of action, physiological roles, genetics, and possible regulation are described. The RNase complement of E. coli and B. subtilis is compared, emphasizing the similarities, but especially the differences, between the two. Included are figures showing the three major RNA metabolic pathways in E. coli and B. subtilis and highlighting specific steps in each of the pathways catalyzed by the different RNases. This compilation of the currently available knowledge about bacterial RNases will be a useful tool for workers in the RNA field and for others interested in learning about this area.
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Affiliation(s)
- David H. Bechhofer
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Murray P. Deutscher
- Department of Biochemistry and Molecular Biology, University of Miami Miller School of Medicine, Miami, FL, USA
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22
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Fredens J, Wang K, de la Torre D, Funke LFH, Robertson WE, Christova Y, Chia T, Schmied WH, Dunkelmann DL, Beránek V, Uttamapinant C, Llamazares AG, Elliott TS, Chin JW. Total synthesis of Escherichia coli with a recoded genome. Nature 2019; 569:514-518. [PMID: 31092918 DOI: 10.1038/s41586-019-1192-5] [Citation(s) in RCA: 281] [Impact Index Per Article: 56.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Accepted: 04/09/2019] [Indexed: 11/09/2022]
Abstract
Nature uses 64 codons to encode the synthesis of proteins from the genome, and chooses 1 sense codon-out of up to 6 synonyms-to encode each amino acid. Synonymous codon choice has diverse and important roles, and many synonymous substitutions are detrimental. Here we demonstrate that the number of codons used to encode the canonical amino acids can be reduced, through the genome-wide substitution of target codons by defined synonyms. We create a variant of Escherichia coli with a four-megabase synthetic genome through a high-fidelity convergent total synthesis. Our synthetic genome implements a defined recoding and refactoring scheme-with simple corrections at just seven positions-to replace every known occurrence of two sense codons and a stop codon in the genome. Thus, we recode 18,214 codons to create an organism with a 61-codon genome; this organism uses 59 codons to encode the 20 amino acids, and enables the deletion of a previously essential transfer RNA.
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Affiliation(s)
- Julius Fredens
- Medical Research Council Laboratory of Molecular Biology, Cambridge, UK
| | - Kaihang Wang
- Medical Research Council Laboratory of Molecular Biology, Cambridge, UK.,Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA
| | | | - Louise F H Funke
- Medical Research Council Laboratory of Molecular Biology, Cambridge, UK
| | | | - Yonka Christova
- Medical Research Council Laboratory of Molecular Biology, Cambridge, UK
| | - Tiongsun Chia
- Medical Research Council Laboratory of Molecular Biology, Cambridge, UK
| | | | | | - Václav Beránek
- Medical Research Council Laboratory of Molecular Biology, Cambridge, UK
| | - Chayasith Uttamapinant
- Medical Research Council Laboratory of Molecular Biology, Cambridge, UK.,School of Biomolecular Science and Engineering, Vidyasirimedhi Institute of Science and Technology (VISTEC), Rayong, Thailand
| | | | - Thomas S Elliott
- Medical Research Council Laboratory of Molecular Biology, Cambridge, UK
| | - Jason W Chin
- Medical Research Council Laboratory of Molecular Biology, Cambridge, UK.
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23
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Hadjeras L, Poljak L, Bouvier M, Morin-Ogier Q, Canal I, Cocaign-Bousquet M, Girbal L, Carpousis AJ. Detachment of the RNA degradosome from the inner membrane of Escherichia coli results in a global slowdown of mRNA degradation, proteolysis of RNase E and increased turnover of ribosome-free transcripts. Mol Microbiol 2019; 111:1715-1731. [PMID: 30903628 PMCID: PMC6850036 DOI: 10.1111/mmi.14248] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/16/2019] [Indexed: 01/03/2023]
Abstract
The reason for RNase E attachment to the inner membrane is largely unknown. To understand the cell biology of RNA degradation, we have characterized a strain expressing RNase E lacking the membrane attachment site (cytoplasmic RNase E). Genome‐wide data show a global slowdown in mRNA degradation. There is no correlation between mRNA stabilization and the function or cellular location of encoded proteins. The activity of cRNase E is comparable to the wild‐type enzyme in vitro, but the mutant protein is unstable in vivo. Autoregulation of cRNase E synthesis compensates for protein instability. cRNase E associates with other proteins to assemble a cytoplasmic RNA degradosome. CsrB/C sRNAs, whose stability is regulated by membrane‐associated CsrD, are stabilized. Membrane attachment of RNase E is thus necessary for CsrB/C turnover. In contrast to mRNA stability, ribosome‐free transcripts are sensitive to inactivation by cRNase E. Our results show that effects on RNA degradation are not due to the differences in the activity or level of cRNase E, or failure to assemble the RNA degradosome. We propose that membrane attachment is necessary for RNase E stability, functional interactions with membrane‐associated regulatory factors and protection of ribosome‐free transcripts from premature interactions with RNase E in the nucleoid.
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Affiliation(s)
- Lydia Hadjeras
- Laboratoire de Microbiologie et de Génétique Moléculaires, Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, UPS, Toulouse, France
| | - Leonora Poljak
- Laboratoire de Microbiologie et de Génétique Moléculaires, Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, UPS, Toulouse, France
| | - Marie Bouvier
- Laboratoire de Microbiologie et de Génétique Moléculaires, Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, UPS, Toulouse, France
| | - Quentin Morin-Ogier
- Laboratoire de Microbiologie et de Génétique Moléculaires, Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, UPS, Toulouse, France
| | - Isabelle Canal
- Laboratoire de Microbiologie et de Génétique Moléculaires, Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, UPS, Toulouse, France
| | | | - Laurence Girbal
- LISBP, Université de Toulouse, CNRS, INRA, INSA, Toulouse, France
| | - Agamemnon J Carpousis
- Laboratoire de Microbiologie et de Génétique Moléculaires, Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, UPS, Toulouse, France
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24
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Component Characterization in a Growth-Dependent Physiological Context: Optimal Experimental Design. Processes (Basel) 2019. [DOI: 10.3390/pr7010052] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Synthetic biology design challenges have driven the use of mathematical models to characterize genetic components and to explore complex design spaces. Traditional approaches to characterization have largely ignored the effect of strain and growth conditions on the dynamics of synthetic genetic circuits, and have thus confounded intrinsic features of the circuit components with cell-level context effects. We present a model that distinguishes an activated gene’s intrinsic kinetics from its physiological context. We then demonstrate an optimal experimental design approach to identify dynamic induction experiments for efficient estimation of the component’s intrinsic parameters. Maximally informative experiments are chosen by formulating the design as an optimal control problem; direct multiple-shooting is used to identify the optimum. Our numerical results suggest that the intrinsic parameters of a genetic component can be more accurately estimated using optimal experimental designs, and that the choice of growth rates, sampling schedule, and input profile each play an important role. The proposed approach to coupled component–host modelling can support gene circuit design across a range of physiological conditions.
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25
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Al-Husini N, Tomares DT, Bitar O, Childers WS, Schrader JM. α-Proteobacterial RNA Degradosomes Assemble Liquid-Liquid Phase-Separated RNP Bodies. Mol Cell 2018; 71:1027-1039.e14. [PMID: 30197298 DOI: 10.1016/j.molcel.2018.08.003] [Citation(s) in RCA: 117] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Revised: 06/11/2018] [Accepted: 07/31/2018] [Indexed: 12/30/2022]
Abstract
Ribonucleoprotein (RNP) granules play an important role in organizing eukaryotic mRNA metabolism via liquid-liquid phase separation (LLPS) of mRNA decay factors into membrane-less organelles in the cytoplasm. Here we show that the bacterium Caulobacter crescentus Ribonuclease (RNase) E assembles RNP LLPS condensates that we term bacterial RNP-bodies (BR-bodies), similar to eukaryotic P-bodies and stress granules. RNase E requires RNA to assemble a BR-body, and disassembly requires RNA cleavage, suggesting BR-bodies provide localized sites of RNA degradation. The unstructured C-terminal domain of RNase E is both necessary and sufficient to assemble the core of the BR-body, is functionally conserved in related α-proteobacteria, and influences mRNA degradation. BR-bodies are rapidly induced under cellular stresses and provide enhanced cell growth under stress. To our knowledge, Caulobacter RNase E is the first bacterial protein identified that forms LLPS condensates, providing an effective strategy for subcellular organization in cells lacking membrane-bound compartments.
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Affiliation(s)
- Nadra Al-Husini
- Department of Biological Sciences, Wayne State University, Detroit, MI, 48202, USA
| | - Dylan T Tomares
- Department of Chemistry, University of Pittsburgh, Pittsburgh, PA, 15260, USA
| | - Obaidah Bitar
- Department of Biological Sciences, Wayne State University, Detroit, MI, 48202, USA
| | - W Seth Childers
- Department of Chemistry, University of Pittsburgh, Pittsburgh, PA, 15260, USA.
| | - Jared M Schrader
- Department of Biological Sciences, Wayne State University, Detroit, MI, 48202, USA.
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26
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Mohanty BK, Kushner SR. Enzymes Involved in Posttranscriptional RNA Metabolism in Gram-Negative Bacteria. Microbiol Spectr 2018; 6:10.1128/microbiolspec.RWR-0011-2017. [PMID: 29676246 PMCID: PMC5912700 DOI: 10.1128/microbiolspec.rwr-0011-2017] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2017] [Indexed: 02/08/2023] Open
Abstract
Gene expression in Gram-negative bacteria is regulated at many levels, including transcription initiation, RNA processing, RNA/RNA interactions, mRNA decay, and translational controls involving enzymes that alter translational efficiency. In this review, we discuss the various enzymes that control transcription, translation, and RNA stability through RNA processing and degradation. RNA processing is essential to generate functional RNAs, while degradation helps control the steady-state level of each individual transcript. For example, all the pre-tRNAs are transcribed with extra nucleotides at both their 5' and 3' termini, which are subsequently processed to produce mature tRNAs that can be aminoacylated. Similarly, rRNAs that are transcribed as part of a 30S polycistronic transcript are matured to individual 16S, 23S, and 5S rRNAs. Decay of mRNAs plays a key role in gene regulation through controlling the steady-state level of each transcript, which is essential for maintaining appropriate protein levels. In addition, degradation of both translated and nontranslated RNAs recycles nucleotides to facilitate new RNA synthesis. To carry out all these reactions, Gram-negative bacteria employ a large number of endonucleases, exonucleases, RNA helicases, and poly(A) polymerase, as well as proteins that regulate the catalytic activity of particular RNases. Under certain stress conditions, an additional group of specialized endonucleases facilitate the cell's ability to adapt and survive. Many of the enzymes, such as RNase E, RNase III, polynucleotide phosphorylase, RNase R, and poly(A) polymerase I, participate in multiple RNA processing and decay pathways.
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Affiliation(s)
| | - Sidney R Kushner
- Department of Genetics
- Department of Microbiology, University of Georgia, Athens, GA 30602
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27
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The Sole DEAD-Box RNA Helicase of the Gastric Pathogen Helicobacter pylori Is Essential for Colonization. mBio 2018; 9:mBio.02071-17. [PMID: 29588407 PMCID: PMC5874925 DOI: 10.1128/mbio.02071-17] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Present in every kingdom of life, generally in multiple copies, DEAD-box RNA helicases are specialized enzymes that unwind RNA secondary structures. They play major roles in mRNA decay, ribosome biogenesis, and adaptation to cold temperatures. Most bacteria have multiple DEAD-box helicases that present both specialized and partially redundant functions. By using phylogenomics, we revealed that the Helicobacter genus, including the major gastric pathogen H. pylori, is among the exceptions, as it encodes a sole DEAD-box RNA helicase. In H. pylori, this helicase, designated RhpA, forms a minimal RNA degradosome together with the essential RNase, RNase J, a major player in the control of RNA decay. Here, we used H. pylori as a model organism with a sole DEAD-box helicase and investigated the role of this helicase in H. pylori physiology, ribosome assembly, and during in vivo colonization. Our data showed that RhpA is dispensable for growth at 37°C but crucial at 33°C, suggesting an essential role of the helicase in cold adaptation. Moreover, we found that a ΔrhpA mutant was impaired in motility and deficient in colonization of the mouse model. RhpA is involved in the maturation of 16S rRNA at 37°C and is associated with translating ribosomes. At 33°C, RhpA is, in addition, recruited to individual ribosomal subunits. Finally, via its role in the RNA degradosome, RhpA directs the regulation of the expression of its partner, RNase J. RhpA is thus a multifunctional enzyme that, in H. pylori, plays a central role in gene regulation and in the control of virulence.IMPORTANCE We present the results of our study on the role of RhpA, the sole DEAD-box RNA helicase encoded by the major gastric pathogen Helicobacter pylori We observed that all the Helicobacter species possess such a sole helicase, in contrast to most free-living bacteria. RhpA is not essential for growth of H. pylori under normal conditions. However, deletion of rhpA leads to a motility defect and to total inhibition of the ability of H. pylori to colonize a mouse model. We also demonstrated that this helicase encompasses most of the functions of its specialized orthologs described so far. We found that RhpA is a key element of the bacterial adaptation to colder temperatures and plays a minor role in ribosome biogenesis. Finally, RhpA regulates transcription of the rnj gene encoding RNase J, its essential partner in the minimal H. pylori RNA degradosome, and thus plays a crucial role in the control of RNA decay.
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Absolute Regulatory Small Noncoding RNA Concentration and Decay Rates Measurements in Escherichia coli. Methods Mol Biol 2018; 1737:231-248. [PMID: 29484597 DOI: 10.1007/978-1-4939-7634-8_14] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Regulation of RNA turnover is of utmost importance for controlling the concentration of transcripts and consequently cellular protein levels. Among the processes controlling RNA decay, small noncoding regulatory RNAs (sRNAs) have recently emerged as major new players. In this chapter, we describe and discuss protocols that can be used to measure sRNA concentration in vivo and to assess sRNA decay rates in Gram-negative bacteria. Precisely, we focus our analyses on the Escherichia coli Gram-negative bacterium as a model. The information described in this chapter provides a guideline to help develop a protocol in order to assess these important parameters and to identify RNA-processing enzymes involved in sRNA degradation processes.
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Song S, Hong S, Jang J, Yeom JH, Park N, Lee J, Lim Y, Jeon JY, Choi HK, Lee M, Ha NC, Lee K. Functional implications of hexameric assembly of RraA proteins from Vibrio vulnificus. PLoS One 2017; 12:e0190064. [PMID: 29261778 PMCID: PMC5738090 DOI: 10.1371/journal.pone.0190064] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2017] [Accepted: 12/07/2017] [Indexed: 11/18/2022] Open
Abstract
RNase E has a pivotal role in the degradation and processing of RNAs in Escherichia coli, and protein inhibitors RraA and RraB control its enzymatic activity. The halophilic pathogenic bacterium Vibrio vulnificus also expresses orthologs of RNase E and RraA—RNase EV, RraAV1, and RraAV2 (herein renamed as VvRNase E, VvRraA1, and VvRraA2). A previous study showed that VvRraA1 actively inhibits the ribonucleolytic activity of VvRNase E by interacting with the C-terminal region of VvRNase E. However, the molecular mechanism underlying the effect of VvRraA1 on the ribonucleolytic activity of VvRNase E has not yet been elucidated. In this study, we report that the oligomer formation of VvRraA proteins affects binding efficiency to VvRNase E as well as inhibitory activity on VvRNase E action. The hexameric structure of VvRraA1 was converted to lower oligomeric forms when the Cys 9 residue was substituted with an Asp residue (VvRraA1-C9D), showing decreased inhibitory activity of VvRraA1 on VvRNase E in vivo. These results indicated that the intermolecular disulfide linkage contributed critically to the hexamerization of VvRraA1 for its proper function. On the contrary, the VvRraA2 that existed in a trimeric state did not bind to or inhibit VvRNase E. An in vitro cleavage assay further showed the reduced inhibitory effect of VvRraA-C9D on VvRNase E activity compared to wild-type VvRraA1. These findings provide insight into how VvRraA proteins can regulate VvRNase E action on its substrate RNA in V. vulnificus. In addition, based on structural and functional comparison of RraA homologs, we suggest that hexameric assembly of RraA homologs may well be required for their action on RNase E-like proteins.
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Affiliation(s)
- Saemee Song
- Department of Agricultural Biotechnology, Seoul National University, Seoul, Republic of Korea
- Department of Molecular Biosciences, Northwestern University, Evanston, Illinois, United States of America
| | - Seokho Hong
- Department of Agricultural Biotechnology, Seoul National University, Seoul, Republic of Korea
| | - Jinyang Jang
- Department of Life Science, Chung-Ang University, Seoul, Republic of Korea
| | - Ji-Hyun Yeom
- Department of Life Science, Chung-Ang University, Seoul, Republic of Korea
| | - Nohra Park
- Department of Agricultural Biotechnology, Seoul National University, Seoul, Republic of Korea
| | - Jaejin Lee
- Department of Life Science, Chung-Ang University, Seoul, Republic of Korea
| | - Yeri Lim
- Department of Life Science, Chung-Ang University, Seoul, Republic of Korea
| | - Jun-Yeong Jeon
- School of Pharmacy, Chung-Ang University, Seoul, Republic of Korea
| | - Hyung-Kyoon Choi
- School of Pharmacy, Chung-Ang University, Seoul, Republic of Korea
| | - Minho Lee
- Department of Life Science, Chung-Ang University, Seoul, Republic of Korea
| | - Nam-Chul Ha
- Department of Agricultural Biotechnology, Seoul National University, Seoul, Republic of Korea
- * E-mail: (NCH); (KL)
| | - Kangseok Lee
- Department of Life Science, Chung-Ang University, Seoul, Republic of Korea
- * E-mail: (NCH); (KL)
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Chao Y, Li L, Girodat D, Förstner KU, Said N, Corcoran C, Śmiga M, Papenfort K, Reinhardt R, Wieden HJ, Luisi BF, Vogel J. In Vivo Cleavage Map Illuminates the Central Role of RNase E in Coding and Non-coding RNA Pathways. Mol Cell 2017; 65:39-51. [PMID: 28061332 PMCID: PMC5222698 DOI: 10.1016/j.molcel.2016.11.002] [Citation(s) in RCA: 186] [Impact Index Per Article: 26.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Revised: 09/26/2016] [Accepted: 10/31/2016] [Indexed: 01/21/2023]
Abstract
Understanding RNA processing and turnover requires knowledge of cleavages by major endoribonucleases within a living cell. We have employed TIER-seq (transiently inactivating an endoribonuclease followed by RNA-seq) to profile cleavage products of the essential endoribonuclease RNase E in Salmonella enterica. A dominating cleavage signature is the location of a uridine two nucleotides downstream in a single-stranded segment, which we rationalize structurally as a key recognition determinant that may favor RNase E catalysis. Our results suggest a prominent biogenesis pathway for bacterial regulatory small RNAs whereby RNase E acts together with the RNA chaperone Hfq to liberate stable 3' fragments from various precursor RNAs. Recapitulating this process in vitro, Hfq guides RNase E cleavage of a representative small-RNA precursor for interaction with a mRNA target. In vivo, the processing is required for target regulation. Our findings reveal a general maturation mechanism for a major class of post-transcriptional regulators.
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Affiliation(s)
- Yanjie Chao
- Institute of Molecular Infection Biology, University of Würzburg, 97080 Würzburg, Germany
| | - Lei Li
- Institute of Molecular Infection Biology, University of Würzburg, 97080 Würzburg, Germany; Core Unit Systems Medicine, University of Würzburg, 97080 Würzburg, Germany
| | - Dylan Girodat
- Alberta RNA Research and Training Institute, Department of Chemistry and Biochemistry, University of Lethbridge, Lethbridge, Alberta T1K 3M4, Canada
| | - Konrad U Förstner
- Institute of Molecular Infection Biology, University of Würzburg, 97080 Würzburg, Germany; Core Unit Systems Medicine, University of Würzburg, 97080 Würzburg, Germany
| | - Nelly Said
- Laboratory of Structural Biochemistry, Freie Universität Berlin, 14195 Berlin, Germany
| | - Colin Corcoran
- Institute of Molecular Infection Biology, University of Würzburg, 97080 Würzburg, Germany
| | - Michał Śmiga
- Institute of Molecular Infection Biology, University of Würzburg, 97080 Würzburg, Germany
| | - Kai Papenfort
- Institute of Molecular Infection Biology, University of Würzburg, 97080 Würzburg, Germany; Department of Biology I, Microbiology, Ludwig-Maximilians-Universität Munich, 82152 Martinsried, Germany
| | - Richard Reinhardt
- Max Planck Genome Centre Cologne, Max Planck Institute for Plant Breeding Research, 50829 Cologne, Germany
| | - Hans-Joachim Wieden
- Alberta RNA Research and Training Institute, Department of Chemistry and Biochemistry, University of Lethbridge, Lethbridge, Alberta T1K 3M4, Canada
| | - Ben F Luisi
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1GA, UK
| | - Jörg Vogel
- Institute of Molecular Infection Biology, University of Würzburg, 97080 Würzburg, Germany; Helmholtz Institute for RNA-based Infection Research (HIRI), 97080 Würzburg, Germany.
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Decreased Expression of Stable RNA Can Alleviate the Lethality Associated with RNase E Deficiency in Escherichia coli. J Bacteriol 2017; 199:JB.00724-16. [PMID: 28167522 DOI: 10.1128/jb.00724-16] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2016] [Accepted: 01/28/2017] [Indexed: 11/20/2022] Open
Abstract
The endoribonuclease RNase E participates in mRNA degradation, rRNA processing, and tRNA maturation in Escherichia coli, but the precise reasons for its essentiality are unclear and much debated. The enzyme is most active on RNA substrates with a 5'-terminal monophosphate, which is sensed by a domain in the enzyme that includes residue R169; E. coli also possesses a 5'-pyrophosphohydrolase, RppH, that catalyzes conversion of 5'-terminal triphosphate to 5'-terminal monophosphate on RNAs. Although the C-terminal half (CTH), beyond residue approximately 500, of RNase E is dispensable for viability, deletion of the CTH is lethal when combined with an R169Q mutation or with deletion of rppH In this work, we show that both these lethalities can be rescued in derivatives in which four or five of the seven rrn operons in the genome have been deleted. We hypothesize that the reduced stable RNA levels under these conditions minimize the need of RNase E to process them, thereby allowing for its diversion for mRNA degradation. In support of this hypothesis, we have found that other conditions that are known to reduce stable RNA levels also suppress one or both lethalities: (i) alterations in relA and spoT, which are expected to lead to increased basal ppGpp levels; (ii) stringent rpoB mutations, which mimic high intracellular ppGpp levels; and (iii) overexpression of DksA. Lethality suppression by these perturbations was RNase R dependent. Our work therefore suggests that its actions on the various substrates (mRNA, rRNA, and tRNA) jointly contribute to the essentiality of RNase E in E. coliIMPORTANCE The endoribonuclease RNase E is essential for viability in many Gram-negative bacteria, including Escherichia coli Different explanations have been offered for its essentiality, including its roles in global mRNA degradation or in the processing of several tRNA and rRNA species. Our work suggests that, rather than its role in the processing of any one particular substrate, its distributed functions on all the different substrates (mRNA, rRNA, and tRNA) are responsible for the essentiality of RNase E in E. coli.
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Seo S, Kim D, Song W, Heo J, Joo M, Lim Y, Yeom JH, Lee K. RraAS1 inhibits the ribonucleolytic activity of RNase ES by interacting with its catalytic domain in Streptomyces coelicolor. J Microbiol 2016; 55:37-43. [PMID: 28035598 DOI: 10.1007/s12275-017-6518-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Revised: 12/15/2016] [Accepted: 12/20/2016] [Indexed: 11/26/2022]
Abstract
RraA is a protein inhibitor of RNase E, which degrades and processes numerous RNAs in Escherichia coli. Streptomyces coelicolor also contains homologs of RNase E and RraA, RNase ES and RraAS1/RraAS2, respectively. Here, we report that, unlike other RraA homologs, RraAS1 directly interacts with the catalytic domain of RNase ES to exert its inhibitory effect. We further show that rraAS1 gene deletion in S. coelicolor results in a higher growth rate and increased production of actinorhodin and undecylprodigiosin, compared with the wild-type strain, suggesting that RraAS1-mediated regulation of RNase ES activity contributes to modulating the cellular physiology of S. coelicolor.
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Affiliation(s)
- Sojin Seo
- Department of Life Science, Chung-Ang University, Seoul, 06974, Republic of Korea
| | - Daeyoung Kim
- Department of Life Science, Chung-Ang University, Seoul, 06974, Republic of Korea
| | - Wooseok Song
- Department of Life Science, Chung-Ang University, Seoul, 06974, Republic of Korea
| | - Jihune Heo
- Department of Life Science, Chung-Ang University, Seoul, 06974, Republic of Korea
| | - Minju Joo
- Department of Life Science, Chung-Ang University, Seoul, 06974, Republic of Korea
| | - Yeri Lim
- Department of Life Science, Chung-Ang University, Seoul, 06974, Republic of Korea
| | - Ji-Hyun Yeom
- Department of Life Science, Chung-Ang University, Seoul, 06974, Republic of Korea.
| | - Kangseok Lee
- Department of Life Science, Chung-Ang University, Seoul, 06974, Republic of Korea.
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Stazic D, Pekarski I, Kopf M, Lindell D, Steglich C. A Novel Strategy for Exploitation of Host RNase E Activity by a Marine Cyanophage. Genetics 2016; 203:1149-59. [PMID: 27182944 PMCID: PMC4937493 DOI: 10.1534/genetics.115.183475] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2015] [Accepted: 05/04/2016] [Indexed: 11/18/2022] Open
Abstract
Previous studies have shown that infection of Prochlorococcus MED4 by the cyanophage P-SSP7 leads to increased transcript levels of host endoribonuclease (RNase) E. However, it has remained enigmatic whether this is part of a host defense mechanism to degrade phage messenger RNA (mRNA) or whether this single-strand RNA-specific RNase is utilized by the phage. Here we describe a hitherto unknown means through which this cyanophage increases expression of RNase E during phage infection and concomitantly protects its own RNA from degradation. We identified two functionally different RNase E mRNA variants, one of which is significantly induced during phage infection. This transcript lacks the 5' UTR, is considerably more stable than the other transcript, and is likely responsible for increased RNase E protein levels during infection. Furthermore, selective enrichment and in vivo analysis of double-stranded RNA (dsRNA) during infection revealed that phage antisense RNAs (asRNAs) sequester complementary mRNAs to form dsRNAs, such that the phage protein-coding transcriptome is nearly completely covered by asRNAs. In contrast, the host protein-coding transcriptome is only partially covered by asRNAs. These data suggest that P-SSP7 orchestrates degradation of host RNA by increasing RNase E expression while masking its own transcriptome from RNase E degradation in dsRNA complexes. We propose that this combination of strategies contributes significantly to phage progeny production.
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Affiliation(s)
- Damir Stazic
- Faculty of Biology, University of Freiburg, D-79104 Freiburg, Germany
| | - Irena Pekarski
- Department of Biology, Technion Institute of Technology, Haifa 32000, Israel
| | - Matthias Kopf
- Faculty of Biology, University of Freiburg, D-79104 Freiburg, Germany
| | - Debbie Lindell
- Department of Biology, Technion Institute of Technology, Haifa 32000, Israel
| | - Claudia Steglich
- Faculty of Biology, University of Freiburg, D-79104 Freiburg, Germany
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34
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Abstract
Gram-negative and gram-positive bacteria use a variety of enzymatic pathways to degrade mRNAs. Although several recent reviews have outlined these pathways, much less attention has been paid to the regulation of mRNA decay. The functional half-life of a particular mRNA, which affects how much protein is synthesized from it, is determined by a combination of multiple factors. These include, but are not necessarily limited to, (a) stability elements at either the 5' or the 3' terminus, (b) posttranscriptional modifications, (c) ribosome density on individual mRNAs, (d) small regulatory RNA (sRNA) interactions with mRNAs, (e) regulatory proteins that alter ribonuclease binding affinities, (f) the presence or absence of endonucleolytic cleavage sites, (g) control of intracellular ribonuclease levels, and (h) physical location within the cell. Changes in physiological conditions associated with environmental alterations can significantly alter the impact of these factors in the decay of a particular mRNA.
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Affiliation(s)
- Bijoy K Mohanty
- Department of Genetics, University of Georgia, Athens, Georgia 30602;
| | - Sidney R Kushner
- Department of Genetics, University of Georgia, Athens, Georgia 30602;
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Abstract
This review provides a description of the known Escherichia coli ribonucleases (RNases), focusing on their structures, catalytic properties, genes, physiological roles, and possible regulation. Currently, eight E. coli exoribonucleases are known. These are RNases II, R, D, T, PH, BN, polynucleotide phosphorylase (PNPase), and oligoribonuclease (ORNase). Based on sequence analysis and catalytic properties, the eight exoribonucleases have been grouped into four families. These are the RNR family, including RNase II and RNase R; the DEDD family, including RNase D, RNase T, and ORNase; the RBN family, consisting of RNase BN; and the PDX family, including PNPase and RNase PH. Seven well-characterized endoribonucleases are known in E. coli. These are RNases I, III, P, E, G, HI, and HII. Homologues to most of these enzymes are also present in Salmonella. Most of the endoribonucleases cleave RNA in the presence of divalent cations, producing fragments with 3'-hydroxyl and 5'-phosphate termini. RNase H selectively hydrolyzes the RNA strand of RNA?DNA hybrids. Members of the RNase H family are widely distributed among prokaryotic and eukaryotic organisms in three distinct lineages, RNases HI, HII, and HIII. It is likely that E. coli contains additional endoribonucleases that have not yet been characterized. First of all, endonucleolytic activities are needed for certain known processes that cannot be attributed to any of the known enzymes. Second, homologues of known endoribonucleases are present in E. coli. Third, endonucleolytic activities have been observed in cell extracts that have different properties from known enzymes.
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36
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Quantitative characterization of gene regulation by Rho dependent transcription termination. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2015; 1849:940-54. [DOI: 10.1016/j.bbagrm.2015.05.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Revised: 04/03/2015] [Accepted: 05/07/2015] [Indexed: 11/23/2022]
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37
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Deutscher MP. How bacterial cells keep ribonucleases under control. FEMS Microbiol Rev 2015; 39:350-61. [PMID: 25878039 DOI: 10.1093/femsre/fuv012] [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] [Accepted: 03/02/2015] [Indexed: 11/13/2022] Open
Abstract
Ribonucleases (RNases) play an essential role in essentially every aspect of RNA metabolism, but they also can be destructive enzymes that need to be regulated to avoid unwanted degradation of RNA molecules. As a consequence, cells have evolved multiple strategies to protect RNAs against RNase action. They also utilize a variety of mechanisms to regulate the RNases themselves. These include post-transcriptional regulation, post-translational modification, trans-acting inhibitors, cellular localization, as well as others that are less well studied. In this review, I will briefly discuss how RNA molecules are protected and then examine in detail our current understanding of the mechanisms known to regulate individual RNases.
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Affiliation(s)
- Murray P Deutscher
- Biochemistry & Molecular Biology, University of Miami, Miami, FL 33136-6129, USA
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38
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Membrane recognition and dynamics of the RNA degradosome. PLoS Genet 2015; 11:e1004961. [PMID: 25647427 PMCID: PMC4372235 DOI: 10.1371/journal.pgen.1004961] [Citation(s) in RCA: 72] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Accepted: 12/17/2014] [Indexed: 01/07/2023] Open
Abstract
RNase E, which is the central component of the multienzyme RNA degradosome, serves as a scaffold for interaction with other enzymes involved in mRNA degradation including the DEAD-box RNA helicase RhlB. Epifluorescence microscopy under live cell conditions shows that RNase E and RhlB are membrane associated, but neither protein forms cytoskeletal-like structures as reported earlier by Taghbalout and Rothfield. We show that association of RhlB with the membrane depends on a direct protein interaction with RNase E, which is anchored to the inner cytoplasmic membrane through an MTS (Membrane Targeting Sequence). Molecular dynamics simulations show that the MTS interacts with the phospholipid bilayer by forming a stabilized amphipathic α-helix with the helical axis oriented parallel to the plane of the bilayer and hydrophobic side chains buried deep in the acyl core of the membrane. Based on the molecular dynamics simulations, we propose that the MTS freely diffuses in the membrane by a novel mechanism in which a large number of weak contacts are rapidly broken and reformed. TIRFm (Total Internal Reflection microscopy) shows that RNase E in live cells rapidly diffuses over the entire inner membrane forming short-lived foci. Diffusion could be part of a scanning mechanism facilitating substrate recognition and cooperativity. Remarkably, RNase E foci disappear and the rate of RNase E diffusion increases with rifampicin treatment. Control experiments show that the effect of rifampicin is specific to RNase E and that the effect is not a secondary consequence of the shut off of E. coli transcription. We therefore interpret the effect of rifampicin as being due to the depletion of RNA substrates for degradation. We propose a model in which formation of foci and constraints on diffusion arise from the transient clustering of RNase E into cooperative degradation bodies. Recent discoveries that two ribonucleases with major roles in mRNA degradation, RNase E of Escherichia coli and RNase Y of Bacillus subtilis, are localized to the inner cytoplasmic membrane suggest that spatial separation of transcription and mRNA degradation are general features of the bacterial cell. Here we show that RNase E rapidly diffuses over the entire inner membrane forming short-lived foci. Results of molecular dynamics simulations lead us to suggest that RNase E interacts with the lipid membrane by a novel mechanism permitting a high degree of translational freedom. We show that RNA substrate is necessary for the formation of RNase E foci and that formation of foci correlates with constraints on the diffusion of RNase E. We therefore propose that foci are degradation bodies in which several RNase E molecules engage an RNA substrate. The sequestration of the mRNA degradation machinery to the inner cytoplasmic membrane has important consequences for mRNA turnover. This organization likely favors formation of polyribosomes on nascent transcripts before they are exposed to the degradation machinery. Rapid diffusion of RNase E on the inner cytoplasmic membrane could be part of a scanning mechanism that facilitates recognition of cytoplasmic polyribosomes and cooperative degradation of mRNA.
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Abstract
mRNA degradation is an important mechanism for controlling gene expression in bacterial cells. This process involves the orderly action of a battery of cellular endonucleases and exonucleases, some universal and others present only in certain species. These ribonucleases function with the assistance of ancillary enzymes that covalently modify the 5' or 3' end of RNA or unwind base-paired regions. Triggered by initiating events at either the 5' terminus or an internal site, mRNA decay occurs at diverse rates that are transcript specific and governed by RNA sequence and structure, translating ribosomes, and bound sRNAs or proteins. In response to environmental cues, bacteria are able to orchestrate widespread changes in mRNA lifetimes by modulating the concentration or specific activity of cellular ribonucleases or by unmasking the mRNA-degrading activity of cellular toxins.
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Affiliation(s)
- Monica P Hui
- Kimmel Center for Biology and Medicine at the Skirball Institute and Department of Microbiology, New York University School of Medicine, New York, NY 10016;
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Esquerré T, Laguerre S, Turlan C, Carpousis AJ, Girbal L, Cocaign-Bousquet M. Dual role of transcription and transcript stability in the regulation of gene expression in Escherichia coli cells cultured on glucose at different growth rates. Nucleic Acids Res 2014; 42:2460-72. [PMID: 24243845 PMCID: PMC3936743 DOI: 10.1093/nar/gkt1150] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2013] [Revised: 10/23/2013] [Accepted: 10/25/2013] [Indexed: 11/13/2022] Open
Abstract
Microorganisms extensively reorganize gene expression to adjust growth rate to changes in growth conditions. At the genomic scale, we measured the contribution of both transcription and transcript stability to regulating messenger RNA (mRNA) concentration in Escherichia coli. Transcriptional control was the dominant regulatory process. Between growth rates of 0.10 and 0.63 h(-1), there was a generic increase in the bulk mRNA transcription. However, many transcripts became less stable and the median mRNA half-life decreased from 4.2 to 2.8 min. This is the first evidence that mRNA turnover is slower at extremely low-growth rates. The destabilization of many, but not all, transcripts at high-growth rate correlated with transcriptional upregulation of genes encoding the mRNA degradation machinery. We identified five classes of growth-rate regulation ranging from mainly transcriptional to mainly degradational. In general, differential stability within polycistronic messages encoded by operons does not appear to be affected by growth rate. We show here that the substantial reorganization of gene expression involving downregulation of tricarboxylic acid cycle genes and acetyl-CoA synthetase at high-growth rates is controlled mainly by transcript stability. Overall, our results demonstrate that the control of transcript stability has an important role in fine-tuning mRNA concentration during changes in growth rate.
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Affiliation(s)
- Thomas Esquerré
- Université de Toulouse; INSA, UPS, INP; LISBP, 135, avenue de Rangueil, 31077 Toulouse, France, INRA, UMR792 Ingénierie des systèmes biologiques et des procédés, 31400 Toulouse, France, CNRS, UMR5504, 31400 Toulouse, France and Laboratoire de Microbiologie et Génétique Moléculaires, UMR5100, Centre National de la Recherche Scientifique et Université Paul Sabatier, 118 Route de Narbonne, 31062 Toulouse, France
| | - Sandrine Laguerre
- Université de Toulouse; INSA, UPS, INP; LISBP, 135, avenue de Rangueil, 31077 Toulouse, France, INRA, UMR792 Ingénierie des systèmes biologiques et des procédés, 31400 Toulouse, France, CNRS, UMR5504, 31400 Toulouse, France and Laboratoire de Microbiologie et Génétique Moléculaires, UMR5100, Centre National de la Recherche Scientifique et Université Paul Sabatier, 118 Route de Narbonne, 31062 Toulouse, France
| | - Catherine Turlan
- Université de Toulouse; INSA, UPS, INP; LISBP, 135, avenue de Rangueil, 31077 Toulouse, France, INRA, UMR792 Ingénierie des systèmes biologiques et des procédés, 31400 Toulouse, France, CNRS, UMR5504, 31400 Toulouse, France and Laboratoire de Microbiologie et Génétique Moléculaires, UMR5100, Centre National de la Recherche Scientifique et Université Paul Sabatier, 118 Route de Narbonne, 31062 Toulouse, France
| | - Agamemnon J. Carpousis
- Université de Toulouse; INSA, UPS, INP; LISBP, 135, avenue de Rangueil, 31077 Toulouse, France, INRA, UMR792 Ingénierie des systèmes biologiques et des procédés, 31400 Toulouse, France, CNRS, UMR5504, 31400 Toulouse, France and Laboratoire de Microbiologie et Génétique Moléculaires, UMR5100, Centre National de la Recherche Scientifique et Université Paul Sabatier, 118 Route de Narbonne, 31062 Toulouse, France
| | - Laurence Girbal
- Université de Toulouse; INSA, UPS, INP; LISBP, 135, avenue de Rangueil, 31077 Toulouse, France, INRA, UMR792 Ingénierie des systèmes biologiques et des procédés, 31400 Toulouse, France, CNRS, UMR5504, 31400 Toulouse, France and Laboratoire de Microbiologie et Génétique Moléculaires, UMR5100, Centre National de la Recherche Scientifique et Université Paul Sabatier, 118 Route de Narbonne, 31062 Toulouse, France
| | - Muriel Cocaign-Bousquet
- Université de Toulouse; INSA, UPS, INP; LISBP, 135, avenue de Rangueil, 31077 Toulouse, France, INRA, UMR792 Ingénierie des systèmes biologiques et des procédés, 31400 Toulouse, France, CNRS, UMR5504, 31400 Toulouse, France and Laboratoire de Microbiologie et Génétique Moléculaires, UMR5100, Centre National de la Recherche Scientifique et Université Paul Sabatier, 118 Route de Narbonne, 31062 Toulouse, France
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Iost I, Bizebard T, Dreyfus M. Functions of DEAD-box proteins in bacteria: current knowledge and pending questions. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2013; 1829:866-77. [PMID: 23415794 DOI: 10.1016/j.bbagrm.2013.01.012] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2012] [Revised: 01/30/2013] [Accepted: 01/31/2013] [Indexed: 11/18/2022]
Abstract
DEAD-box proteins are RNA-dependent ATPases that are widespread in all three kingdoms of life. They are thought to rearrange the structures of RNA or ribonucleoprotein complexes but their exact mechanism of action is rarely known. Whereas in yeast most DEAD-box proteins are essential, no example of an essential bacterial DEAD-box protein has been reported so far; at most, their absence results in cold-sensitive growth. Moreover, whereas yeast DEAD-box proteins are implicated in virtually all reactions involving RNA, in E. coli (the bacterium where DEAD-box proteins have been mostly studied) their role is limited to ribosome biogenesis, mRNA degradation, and possibly translation initiation. Plausible reasons for these differences are discussed here. In spite of their dispensability, E. coli DEAD-box proteins are valuable models for the mechanism of action of DEAD-box proteins in general because the reactions in which they participate can be reproduced in vitro. Here we review our present understanding of this mechanism of action. Using selected examples for which information is available: (i) we describe how, by interacting directly with a particular RNA motif or by binding to proteins that themselves recognize such a motif, DEAD-box proteins are brought to their specific RNA substrate(s); (ii) we discuss the nature of the structural transitions that DEAD-box proteins induce on their substrates; and (iii) we analyze the reasons why these proteins are mostly important at low temperatures. This article is part of a Special Issue entitled: The Biology of RNA helicases-Modulation for life.
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Affiliation(s)
- Isabelle Iost
- Univ. Bordeaux, ARNA Laboratory, F-33000 Bordeaux, France.
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42
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Mackie GA. RNase E: at the interface of bacterial RNA processing and decay. Nat Rev Microbiol 2012; 11:45-57. [DOI: 10.1038/nrmicro2930] [Citation(s) in RCA: 236] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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When ribonucleases come into play in pathogens: a survey of gram-positive bacteria. Int J Microbiol 2012; 2012:592196. [PMID: 22550495 PMCID: PMC3328962 DOI: 10.1155/2012/592196] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2011] [Accepted: 11/27/2011] [Indexed: 11/20/2022] Open
Abstract
It is widely acknowledged that RNA stability plays critical roles in bacterial adaptation and survival in different environments like those encountered when bacteria infect a host. Bacterial ribonucleases acting alone or in concert with regulatory RNAs or RNA binding proteins are the mediators of the regulatory outcome on RNA stability. We will give a current update of what is known about ribonucleases in the model Gram-positive organism Bacillus subtilis and will describe their established roles in virulence in several Gram-positive pathogenic bacteria that are imposing major health concerns worldwide. Implications on bacterial evolution through stabilization/transfer of genetic material (phage or plasmid DNA) as a result of ribonucleases' functions will be covered. The role of ribonucleases in emergence of antibiotic resistance and new concepts in drug design will additionally be discussed.
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Anupama K, Leela JK, Gowrishankar J. Two pathways for RNase E action in Escherichia coli in vivo and bypass of its essentiality in mutants defective for Rho-dependent transcription termination. Mol Microbiol 2011; 82:1330-48. [PMID: 22026368 DOI: 10.1111/j.1365-2958.2011.07895.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The endonuclease RNase E of Escherichia coli is essential for viability, but deletion of its C-terminal half (CTH) is not lethal. RNase E preferentially acts on 5'-monophosphorylated RNA whose generation from primary transcripts is catalysed by RppH, but ΔRppH strains are viable. Here we show that the RNase E-ΔCTH ΔRppH combination is lethal, and that the lethality is suppressed by rho or nusG mutations impairing Rho-dependent transcription termination. Lethality was correlated with defects in bulk mRNA decay and tRNA processing, which were reversed by the rho suppressor. Lethality suppression was dependent on RNase H1 or the helicase UvsW of phage T4, both of which act to remove RNA-DNA hybrids (R-loops). The rho and nusG mutations also rescued inviability of a double alteration R169Q (that abolishes 5'-sensing) with ΔCTH in RNase E, as also that of conditional RNase E deficiency. We suggest that the ΔCTH alteration leads to loss of a second 5'-end-independent pathway of RNase E action. We further propose that an increased abundance of R-loops in the rho and nusG mutants, although ordinarily inimical to growth, contributes to rescue the lethality associated with loss of the two RNase E cleavage pathways by providing an alternative means of RNA degradation.
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Affiliation(s)
- K Anupama
- Laboratory of Bacterial Genetics, Centre for DNA Fingerprinting and Diagnostics, Hyderabad 500 001, India
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45
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Silva IJ, Saramago M, Dressaire C, Domingues S, Viegas SC, Arraiano CM. Importance and key events of prokaryotic RNA decay: the ultimate fate of an RNA molecule. WILEY INTERDISCIPLINARY REVIEWS-RNA 2011; 2:818-36. [PMID: 21976285 DOI: 10.1002/wrna.94] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Affiliation(s)
- Inês Jesus Silva
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Apartado 127, Oeiras, Portugal
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46
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Nguyen LK, Kulasiri D. Distinct noise-controlling roles of multiple negative feedback mechanisms in a prokaryotic operon system. IET Syst Biol 2011; 5:145-56. [PMID: 21405203 DOI: 10.1049/iet-syb.2010.0020] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Molecular fluctuations are known to affect dynamics of cellular systems in important ways. Studies aimed at understanding how molecular systems of certain regulatory architectures control noise therefore become essential. The interplay between feedback regulation and noise has been previously explored for cellular networks governed by a single negative feedback loop. However, similar issues within networks consisting of more complex regulatory structures remain elusive. The authors investigate how negative feedback loops manage noise within a biochemical cascade concurrently governed by multiple negative feedback loops, using the prokaryotic tryptophan (trp) operon system in Escherechia coli as the model system. To the authors knowledge, this is the first study of noise in the trp operon system. They show that the loops in the trp operon system possess distinct, even opposing, noise-controlling effects despite their seemingly analogous feedback structures. The enzyme inhibition loop, although controlling the last reaction of the cascade, was found to suppress noise not only for the tryptophan output but also for other upstream components. In contrast, the Repression (Rep) loop enhances noise for all systems components. Attenuation (Att) poses intermediate effects by attenuating noise for the upstream components but promoting noise for components downstream of its target. Regarding noise at the output tryptophan, Rep and Att can be categorised as noise-enhancing loops whereas Enzyme Inhibition as a noise-reducing loop. These findings suggest novel implications in how cellular systems with multiple feedback mechanisms control noise. [Includes supplementary material].
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48
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Tang J, Luo M, Niu S, Zhou H, Cai X, Zhang W, Hu Y, Yin Y, Huang A, Wang D. The crystal structure of hexamer RraA from Pseudomonas aeruginosa reveals six conserved protein-protein interaction sites. Protein J 2011; 29:583-90. [PMID: 21063756 DOI: 10.1007/s10930-010-9293-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
RNase E functions as the rate-limiting enzyme in the global mRNA metabolism as well as in the maturation of functional RNAs. The endoribonuclease, binding to the PNPase trimer, the RhlB monomer, and the enolase dimer, assembles into an RNA degradosome necessary for effective RNA metabolism. The RNase E processing is found to be negatively regulated by the protein modulator RraA which appears to work by interacting with the non-catalytic region of the endoribonuclease and significantly reduce the interaction between RNase E and PNPase, RhlB and enolase of the RNA degradosome. Here we report the crystal structure of RraA from P. aeruginosa to a resolution of 2.0 Å. The overall architecture of RraA is very similar to other known RraAs, which are highly structurally conserved. Gel filtration and dynamic light scattering experiments suggest that the protein regulator is arranged as a hexamer, consistent with the crystal packing of "a dimer of trimer" arrangement. Structure and sequence conservation analysis suggests that the hexamer RraA contains six putative charged protein-protein interaction sites which may serve as binding sites for RNase E.
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Affiliation(s)
- Jian Tang
- Key Laboratory of Molecular Biology on Infectious Diseases, Ministry of Education, Chongqing Medical University, Chongqing 400016, People's Republic of China
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49
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Condon C, Bechhofer DH. Regulated RNA stability in the Gram positives. Curr Opin Microbiol 2011; 14:148-54. [PMID: 21334965 DOI: 10.1016/j.mib.2011.01.010] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2010] [Accepted: 01/28/2011] [Indexed: 10/18/2022]
Abstract
Regulation of bacterial gene expression at the post-transcriptional level has emerged as a major control mechanism, although not yet as well recognized as the mechanisms of control at the transcriptional level. In this article, we focus on regulated RNA decay in the control of gene expression in Gram-positive organisms, with an emphasis on Bacillus subtilis. Discovery of new ribonuclease activities in B. subtilis and other Gram-positive species, especially the dual-functioning RNase J1, which specifies both an endonuclease activity and the long-sought bacterial 5'-to-3' exoribonuclease activity, has led to the recognition of intriguing mechanisms of gene regulation at the level of RNA decay.
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Affiliation(s)
- Ciarán Condon
- CNRS UPR 9073 (affiliated with Université de Paris 7 - Denis Diderot), Institut de Biologie Physico-Chimique, 13 rue Pierre et Marie Curie, 75005 Paris, France
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50
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Karzbrun E, Shin J, Bar-Ziv RH, Noireaux V. Coarse-grained dynamics of protein synthesis in a cell-free system. PHYSICAL REVIEW LETTERS 2011; 106:048104. [PMID: 21405367 DOI: 10.1103/physrevlett.106.048104] [Citation(s) in RCA: 92] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2010] [Indexed: 05/30/2023]
Abstract
A complete gene expression reaction is reconstituted in a cell-free system comprising the entire endogenous transcription, translation, as well as mRNA and protein degradation machinery of E. coli. In dissecting the major reaction steps, we derive a coarse-grained enzymatic description of biosynthesis and degradation, from which ten relevant rate constants and concentrations are determined. Governed by zeroth-order degradation, protein expression follows a sharp transition from undetectable levels to constant-rate accumulation, without reaching steady state.
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Affiliation(s)
- Eyal Karzbrun
- Department of Materials and Interfaces, the Weizmann Institute of Science, Rehovot, Israel
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