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Kretz J, Börner J, Friedrich T, McIntosh M, Procida-Kowalski T, Gerken F, Wilhelm J, Klug G. Function of the RNA-targeting class 2 type VI CRISPR Cas system of Rhodobacter capsulatus. Front Microbiol 2024; 15:1384543. [PMID: 38741736 PMCID: PMC11089165 DOI: 10.3389/fmicb.2024.1384543] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2024] [Accepted: 04/15/2024] [Indexed: 05/16/2024] Open
Abstract
Bacteria use CRISPR Cas systems to defend against invading foreign nucleic acids, e.g., phage genomes, plasmids or mobile genetic elements. Some CRISPR Cas systems were reported to have physiological importance under a variety of abiotic stress conditions. We used physiological tests under different stress conditions and RNA-seq analyses to address the possible function of the RNA-targeting class 2 type VI CRISPR Cas system of the facultative phototrophic α-proteobacterium Rhodobacter capsulatus. Expression of the system was low under exponential non-stress conditions and high during oxidative stress, membrane stress and in stationary phase. Induction of the CRISPR Cas system in presence of a target protospacer RNA resulted in a growth arrest of R. capsulatus. RNA-seq revealed a strong alteration of the R. capsulatus transcriptome when cas13a was induced in presence of a target protospacer. RNA 5' end mapping indicated that the CRISPR Cas-dependent transcriptome remodeling is accompanied by fragmentation of cellular RNAs, e.g., for mRNAs originating from a genomic locus which encodes multiple ribosomal proteins and the RNA polymerase subunits RpoA, RpoB and RpoC. The data suggest a function of this CRISPR Cas system in regulated growth arrest, which may prevent the spread of phages within the population.
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Affiliation(s)
- Jonas Kretz
- Institute of Microbiology and Molecular Biology, Justus-Liebig-University, Giessen, Germany
| | - Janek Börner
- Institute of Microbiology and Molecular Biology, Justus-Liebig-University, Giessen, Germany
| | - Tobias Friedrich
- Institute of Biochemistry, Justus-Liebig-University, Giessen, Germany
- Biomedical Informatics and Systems Medicine, Justus-Liebig-University, Giessen, Germany
| | - Matthew McIntosh
- Institute of Microbiology and Molecular Biology, Justus-Liebig-University, Giessen, Germany
| | | | - Florian Gerken
- Institute of Microbiology and Molecular Biology, Justus-Liebig-University, Giessen, Germany
| | - Jochen Wilhelm
- Institute for Lung Health, Justus-Liebig-University, Giessen, Germany
| | - Gabriele Klug
- Institute of Microbiology and Molecular Biology, Justus-Liebig-University, Giessen, Germany
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2
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Börner J, Friedrich T, Klug G. RNase III participates in control of quorum sensing, pigmentation and oxidative stress resistance in Rhodobacter sphaeroides. Mol Microbiol 2023; 120:874-892. [PMID: 37823424 DOI: 10.1111/mmi.15181] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2023] [Revised: 09/21/2023] [Accepted: 09/26/2023] [Indexed: 10/13/2023]
Abstract
RNase III is a dsRNA-specific endoribonuclease, highly conserved in bacteria and eukarya. In this study, we analysed the effects of inactivation of RNase III on the transcriptome and the phenotype of the facultative phototrophic α-proteobacterium Rhodobacter sphaeroides. RNA-seq revealed an unexpectedly high amount of genes with increased expression located directly downstream to the rRNA operons. Chromosomal insertion of additional transcription terminators restored wild type-like expression of the downstream genes, indicating that RNase III may modulate the rRNA transcription termination in R. sphaeroides. Furthermore, we identified RNase III as a major regulator of quorum-sensing autoinducer synthesis in R. sphaeroides. It negatively controls the expression of the autoinducer synthase CerI by reducing cerI mRNA stability. In addition, RNase III inactivation caused altered resistance against oxidative stress and impaired formation of photosynthetically active pigment-protein complexes. We also observed an increase in the CcsR small RNAs that were previously shown to promote resistance to oxidative stress. Taken together, our data present interesting insights into RNase III-mediated regulation and expand the knowledge on the function of this important enzyme in bacteria.
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Affiliation(s)
- Janek Börner
- Institute of Microbiology and Molecular Biology, Justus-Liebig-University Giessen, Giessen, Germany
| | - Tobias Friedrich
- Biomedical Informatics and Systems Medicine, Justus-Liebig-University Giessen, Giessen, Germany
- Institute of Biochemistry, Justus-Liebig-University Giessen, Giessen, Germany
| | - Gabriele Klug
- Institute of Microbiology and Molecular Biology, Justus-Liebig-University Giessen, Giessen, Germany
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3
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Broglia L, Le Rhun A, Charpentier E. Methodologies for bacterial ribonuclease characterization using RNA-seq. FEMS Microbiol Rev 2023; 47:fuad049. [PMID: 37656885 PMCID: PMC10503654 DOI: 10.1093/femsre/fuad049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2023] [Revised: 08/06/2023] [Accepted: 08/23/2023] [Indexed: 09/03/2023] Open
Abstract
Bacteria adjust gene expression at the post-transcriptional level through an intricate network of small regulatory RNAs and RNA-binding proteins, including ribonucleases (RNases). RNases play an essential role in RNA metabolism, regulating RNA stability, decay, and activation. These enzymes exhibit species-specific effects on gene expression, bacterial physiology, and different strategies of target recognition. Recent advances in high-throughput RNA sequencing (RNA-seq) approaches have provided a better understanding of the roles and modes of action of bacterial RNases. Global studies aiming to identify direct targets of RNases have highlighted the diversity of RNase activity and RNA-based mechanisms of gene expression regulation. Here, we review recent RNA-seq approaches used to study bacterial RNases, with a focus on the methods for identifying direct RNase targets.
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Affiliation(s)
- Laura Broglia
- Max Planck Unit for the Science of Pathogens, D-10117 Berlin, Germany
- Center for Human Technologies, Istituto Italiano di Tecnologia, 16152 Genova, Italy
| | - Anaïs Le Rhun
- Max Planck Unit for the Science of Pathogens, D-10117 Berlin, Germany
- Univ. Bordeaux, CNRS, INSERM, ARNA, UMR 5320, U1212, F-33000 Bordeaux, France
| | - Emmanuelle Charpentier
- Max Planck Unit for the Science of Pathogens, D-10117 Berlin, Germany
- Institute for Biology, Humboldt University, D-10115 Berlin, Germany
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4
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Sazykin IS, Sazykina MA. The role of oxidative stress in genome destabilization and adaptive evolution of bacteria. Gene X 2023; 857:147170. [PMID: 36623672 DOI: 10.1016/j.gene.2023.147170] [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: 08/09/2022] [Revised: 12/14/2022] [Accepted: 01/03/2023] [Indexed: 01/09/2023] Open
Abstract
The review is devoted to bacterial genome destabilization by oxidative stress. The article discusses the main groups of substances causing such stress. Stress regulons involved in destabilization of genetic material and mechanisms enhancing mutagenesis, bacterial genome rearrangements, and horizontal gene transfer, induced by oxidative damage to cell components are also considered. Based on the analysis of publications, it can be claimed that rapid development of new food substrates and ecological niches by microorganisms occurs due to acceleration of genetic changes induced by oxidative stress, mediated by several stress regulons (SOS, RpoS and RpoE) and under selective pressure. The authors conclude that non-lethal oxidative stress is probably-one of the fundamental processes that guide evolution of prokaryotes and a powerful universal trigger for adaptive destabilization of bacterial genome under changing environmental conditions.
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Affiliation(s)
- I S Sazykin
- Southern Federal University, 194/2 Stachki Avenue, Rostov-on-Don 344090, Russian Federation
| | - M A Sazykina
- Southern Federal University, 194/2 Stachki Avenue, Rostov-on-Don 344090, Russian Federation.
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5
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Spanka DT, Grützner J, Jäger A, Klug G. A Small RNA, UdsC, Interacts with the R poHII mRNA and Affects the Motility and Stress Resistance of Rhodobacter sphaeroides. Int J Mol Sci 2022; 23:ijms232415486. [PMID: 36555125 PMCID: PMC9779115 DOI: 10.3390/ijms232415486] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Revised: 12/01/2022] [Accepted: 12/02/2022] [Indexed: 12/12/2022] Open
Abstract
sRNAs have an important role in the regulation of bacterial gene expression. The sRNA, UdsC, of Rhodobacter sphaeroides is derived from the 3' UTR of the RSP_7527 mRNA, which encodes a hypothetical protein. Here, we showed the effect of UdsC on the resistance of Rhodobacter sphaeroides to hydrogen peroxide and on its motility. In vitro binding assays supported the direct interaction of UdsC with the 5' UTR of the rpoHII mRNA. RpoHII is an alternative sigma factor with an important role in stress responses in R. sphaeroides, including its response to hydrogen peroxide. We also demonstrated that RpoHII controls the expression of the torF gene, which encodes an important regulator of motility genes. This strongly suggested that the observed effect of UdsC on TorF expression is indirect and mediated by RpoHII.
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Regmi R, Penton CR, Anderson J, Gupta VVSR. Do small RNAs unlock the below ground microbiome-plant interaction mystery? Front Mol Biosci 2022; 9:1017392. [PMID: 36406267 PMCID: PMC9670543 DOI: 10.3389/fmolb.2022.1017392] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Accepted: 10/18/2022] [Indexed: 11/02/2023] Open
Abstract
Over the past few decades, regulatory RNAs, such as small RNAs (sRNAs), have received increasing attention in the context of host-microbe interactions due to their diverse roles in controlling various biological processes in eukaryotes. In addition, studies have identified an increasing number of sRNAs with novel functions across a wide range of bacteria. What is not well understood is why cells regulate gene expression through post-transcriptional mechanisms rather than at the initiation of transcription. The finding of a multitude of sRNAs and their identified associated targets has allowed further investigation into the role of sRNAs in mediating gene regulation. These foundational data allow for further development of hypotheses concerning how a precise control of gene activity is accomplished through the combination of transcriptional and post-transcriptional regulation. Recently, sRNAs have been reported to participate in interkingdom communication and signalling where sRNAs originating from one kingdom are able to target or control gene expression in another kingdom. For example, small RNAs of fungal pathogens that silence plant genes and vice-versa plant sRNAs that mediate bacterial gene expression. However, there is currently a lack of evidence regarding sRNA-based inter-kingdom signalling across more than two interacting organisms. A habitat that provides an excellent opportunity to investigate interconnectivity is the plant rhizosphere, a multifaceted ecosystem where plants and associated soil microbes are known to interact. In this paper, we discuss how the interconnectivity of bacteria, fungi, and plants within the rhizosphere may be mediated by bacterial sRNAs with a particular focus on disease suppressive and non-suppressive soils. We discuss the potential roles sRNAs may play in the below-ground world and identify potential areas of future research, particularly in reference to the regulation of plant immunity genes by bacterial and fungal communities in disease-suppressive and non-disease-suppressive soils.
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Affiliation(s)
- Roshan Regmi
- CSIRO Microbiomes for One Systems Health, Waite Campus, Canberra, SA, Australia
- CSIRO Agriculture and Food, Waite Campus, Canberra, SA, Australia
| | - C. Ryan Penton
- CSIRO Agriculture and Food, Waite Campus, Canberra, SA, Australia
- College of Integrative Sciences and Arts, Arizona State University, Mesa, AZ, United States
- Center for Fundamental and Applied Microbiomics, Biodesign Institute, Arizona State University, Tempe, AZ, United States
| | - Jonathan Anderson
- CSIRO Microbiomes for One Systems Health, Waite Campus, Canberra, SA, Australia
- CSIRO Agriculture and Food, Canberra, SA, Australia
| | - Vadakattu V. S. R. Gupta
- CSIRO Microbiomes for One Systems Health, Waite Campus, Canberra, SA, Australia
- CSIRO Agriculture and Food, Waite Campus, Canberra, SA, Australia
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Spanka DT, Klug G. Maturation of UTR-Derived sRNAs Is Modulated during Adaptation to Different Growth Conditions. Int J Mol Sci 2021; 22:ijms222212260. [PMID: 34830143 PMCID: PMC8625941 DOI: 10.3390/ijms222212260] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Revised: 11/02/2021] [Accepted: 11/08/2021] [Indexed: 12/02/2022] Open
Abstract
Small regulatory RNAs play a major role in bacterial gene regulation by binding their target mRNAs, which mostly influences the stability or translation of the target. Expression levels of sRNAs are often regulated by their own promoters, but recent reports have highlighted the presence and importance of sRNAs that are derived from mRNA 3′ untranslated regions (UTRs). In this study, we investigated the maturation of 5′ and 3′ UTR-derived sRNAs on a global scale in the facultative phototrophic alphaproteobacterium Rhodobacter sphaeroides. Including some already known UTR-derived sRNAs like UpsM or CcsR1-4, 14 sRNAs are predicted to be located in 5 UTRs and 16 in 3′ UTRs. The involvement of different ribonucleases during maturation was predicted by a differential RNA 5′/3′ end analysis based on RNA next generation sequencing (NGS) data from the respective deletion strains. The results were validated in vivo and underline the importance of polynucleotide phosphorylase (PNPase) and ribonuclease E (RNase E) during processing and maturation. The abundances of some UTR-derived sRNAs changed when cultures were exposed to external stress conditions, such as oxidative stress and also during different growth phases. Promoter fusions revealed that this effect cannot be solely attributed to an altered transcription rate. Moreover, the RNase E dependent cleavage of several UTR-derived sRNAs varied significantly during the early stationary phase and under iron depletion conditions. We conclude that an alteration of ribonucleolytic processing influences the levels of UTR-derived sRNAs, and may thus indirectly affect their mRNA targets.
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Gelsinger DR, Reddy R, Whittington K, Debic S, DiRuggiero J. Post-transcriptional regulation of redox homeostasis by the small RNA SHOxi in haloarchaea. RNA Biol 2021; 18:1867-1881. [PMID: 33522404 PMCID: PMC8583180 DOI: 10.1080/15476286.2021.1874717] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2020] [Revised: 01/06/2021] [Accepted: 01/07/2021] [Indexed: 11/13/2022] Open
Abstract
While haloarchaea are highly resistant to oxidative stress, a comprehensive understanding of the processes regulating this remarkable response is lacking. Oxidative stress-responsive small non-coding RNAs (sRNAs) have been reported in the model archaeon, Haloferax volc anii, but targets and mechanisms have not been elucidated. Using a combination of high throughput and reverse molecular genetic approaches, we elucidated the functional role of the most up-regulated intergenic sRNA during oxidative stress in H. volcanii, named Small RNA in Haloferax Oxidative Stress (SHOxi). SHOxi was predicted to form a stable secondary structure with a conserved stem-loop region as the potential binding site for trans-targets. NAD-dependent malic enzyme mRNA, identified as a putative target of SHOxi, interacted directly with a putative 'seed' region within the predicted stem loop of SHOxi. Malic enzyme catalyzes the oxidative decarboxylation of malate into pyruvate using NAD+ as a cofactor. The destabilization of malic enzyme mRNA, and the decrease in the NAD+/NADH ratio, resulting from the direct RNA-RNA interaction between SHOxi and its trans-target was essential for the survival of H. volcanii to oxidative stress. These findings indicate that SHOxi likely regulates redox homoeostasis during oxidative stress by the post-transcriptional destabilization of malic enzyme mRNA. SHOxi-mediated regulation provides evidence that the fine-tuning of metabolic cofactors could be a core strategy to mitigate damage from oxidative stress and confer resistance. This study is the first to establish the regulatory effects of sRNAs on mRNAs during the oxidative stress response in Archaea.
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Affiliation(s)
| | - Rahul Reddy
- Department of Biology, The Johns Hopkins University, Baltimore, Maryland, USA
| | | | - Sara Debic
- Department of Biology, The Johns Hopkins University, Baltimore, Maryland, USA
| | - Jocelyne DiRuggiero
- Department of Biology, The Johns Hopkins University, Baltimore, Maryland, USA
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McIntosh M, Köchling T, Latz A, Kretz J, Heinen S, Konzer A, Klug G. A major checkpoint for protein expression in Rhodobacter sphaeroides during heat stress response occurs at the level of translation. Environ Microbiol 2021; 23:6483-6502. [PMID: 34668288 DOI: 10.1111/1462-2920.15818] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Accepted: 10/05/2021] [Indexed: 12/24/2022]
Abstract
Temperature above the physiological optimum is a stress condition frequently faced by bacteria in their natural environments. Here, we were interested in the correlation between levels of RNA and protein under heat stress. Changes in RNA and protein levels were documented in cultures of Rhodobacter sphaeroides using RNA sequencing, quantitative mass spectrometry, western blot analysis, in vivo [35 S] methionine-labelling and plasmid-borne reporter fusions. Changes in the transcriptome were extensive. Strikingly, the proteome remained unchanged except for very few proteins. Examples include a heat shock protein, a DUF1127 protein of unknown function and sigma factor proteins from leaderless transcripts. Insight from this study indicates that R. sphaeroides responds to heat stress by producing a broad range of transcripts while simultaneously preventing translation from nearly all of them, and that this selective production of protein depends on the untranslated region of the transcript. We conclude that measurements of transcript abundance are insufficient to understand gene regulation. Rather, translation can be an important checkpoint for protein expression under certain environmental conditions. Furthermore, during heat shock, regulation at the level of transcription might represent preparation for survival in an unpredictable environment while regulation at translation ensures production of only a few proteins.
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Affiliation(s)
- Matthew McIntosh
- Institute of Microbiology und Molecular Biology, IFZ, Justus-Liebig-Universität, 35292, Giessen, Germany
| | - Thorsten Köchling
- Institute of Microbiology und Molecular Biology, IFZ, Justus-Liebig-Universität, 35292, Giessen, Germany
| | - Anna Latz
- Institute of Microbiology und Molecular Biology, IFZ, Justus-Liebig-Universität, 35292, Giessen, Germany
| | - Jonas Kretz
- Institute of Microbiology und Molecular Biology, IFZ, Justus-Liebig-Universität, 35292, Giessen, Germany
| | - Sandra Heinen
- Institute of Microbiology und Molecular Biology, IFZ, Justus-Liebig-Universität, 35292, Giessen, Germany
| | - Anne Konzer
- Biomolecular Mass Spectrometry, Max-Planck-Institute for Heart and Lung Research, Bad Nauheim, Germany
| | - Gabriele Klug
- Institute of Microbiology und Molecular Biology, IFZ, Justus-Liebig-Universität, 35292, Giessen, Germany
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Evguenieva-Hackenberg E. Riboregulation in bacteria: From general principles to novel mechanisms of the trp attenuator and its sRNA and peptide products. WILEY INTERDISCIPLINARY REVIEWS-RNA 2021; 13:e1696. [PMID: 34651439 DOI: 10.1002/wrna.1696] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Revised: 08/25/2021] [Accepted: 09/10/2021] [Indexed: 12/26/2022]
Abstract
Gene expression strategies ensuring bacterial survival and competitiveness rely on cis- and trans-acting RNA-regulators (riboregulators). Among the cis-acting riboregulators are transcriptional and translational attenuators, and antisense RNAs (asRNAs). The trans-acting riboregulators are small RNAs (sRNAs) that bind proteins or base pairs with other RNAs. This classification is artificial since some regulatory RNAs act both in cis and in trans, or function in addition as small mRNAs. A prominent example is the archetypical, ribosome-dependent attenuator of tryptophan (Trp) biosynthesis genes. It responds by transcription attenuation to two signals, Trp availability and inhibition of translation, and gives rise to two trans-acting products, the attenuator sRNA rnTrpL and the leader peptide peTrpL. In Escherichia coli, rnTrpL links Trp availability to initiation of chromosome replication and in Sinorhizobium meliloti, it coordinates regulation of split tryptophan biosynthesis operons. Furthermore, in S. meliloti, peTrpL is involved in mRNA destabilization in response to antibiotic exposure. It forms two types of asRNA-containing, antibiotic-dependent ribonucleoprotein complexes (ARNPs), one of them changing the target specificity of rnTrpL. The posttranscriptional role of peTrpL indicates two emerging paradigms: (1) sRNA reprograming by small molecules and (2) direct involvement of antibiotics in regulatory RNPs. They broaden our view on RNA-based mechanisms and may inspire new approaches for studying, detecting, and using antibacterial compounds. This article is categorized under: RNA Interactions with Proteins and Other Molecules > Small Molecule-RNA Interactions RNA Interactions with Proteins and Other Molecules > RNA-Protein Complexes Regulatory RNAs/RNAi/Riboswitches > Regulatory RNAs.
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Adnan F, Jalil A, Ahmed T, Rahman A, Dawood N, Haider G, Siddiqui MF, Rostock L, Guenther S, Schaufler K. TRAP transporter TakP: a key player in the resistance against selenite-induced oxidative stress in Rhodobacter sphaeroides. Microbiol Res 2021; 252:126828. [PMID: 34543948 DOI: 10.1016/j.micres.2021.126828] [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: 06/25/2020] [Revised: 03/28/2021] [Accepted: 07/20/2021] [Indexed: 11/24/2022]
Abstract
Almost one-third of all proteins require metal ions as an essential component in key biological processes and approximately half of all enzymes are associated with one or more metal ions. The naturally occurring selenium is very toxic at higher levels, but few bacteria can reduce it into the less toxic insoluble elemental selenium. Selenium is required for the synthesis of selenocysteine, an essential residue involved in the active sites of various enzymes. The purple non-sulphur bacteria, Rhodobacter sphaeroidesis demonstrated for its selenite reduction capacity. The exact mechanism of selenite toxicity is unknown but it reacts with glutathione to form selenodiglutathione, producing the highly toxic compounds namely, H2O2and O2-. A R. sphaeroidesstrain with mutated takP gene, a member of the TRAP (tripartite ATP-independent periplasmic) family of transporter, was reported to be showing more resistance towards selenite in the growth medium but the reason for the resistance is unknown. TRAP transporters are the best-studied family of substrate-binding protein and in our previous study it was confirmed that the gene takP in R. sphaeroides is down-regulated by a small non-coding RNA SorY, providing more resistance to the bacterium against the oxidative stress. By comparative growth analysis and sensitivity assays in the presence of 2 mM selenite, it was observed that the SorY knockout strain is more sensitive to selenite while overexpression of the sRNA conferred more resistance to the bacterium like the takP mutant strain. TakP is involved in the import of malate into the cell, which under oxidative stress needs to be down-regulated to limit malate flux into the cell. Limited malate flux leads to metabolic rearrangements in the cell to avoid excessive generation of prooxidant NADH and facilitate constant generation of antioxidant NADPH. In the presence and absence of selenite, a drastic increase in the NADPH and decrease in the NADH levels are reported respectively. Accumulation of metallic selenium in the cytoplasm was detected via atomic absorption spectrophotometer and our analysis clearly demonstrated the presence of more selenium in the electron micrographs of the SorY knockout strain compared to the takP mutant grown under dark semi-aerobic growth conditions in the presence of selenite. Hence based on our analysis, it is confirmed that lack of TakP transporter led to reduced selenite influx into the cytoplasm, relieving cells with limited generation of ROS, eventually exhibiting more resistance against selenite-induced oxidative stress.
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Affiliation(s)
- Fazal Adnan
- Atta ur Rahman School of Applied Biosciences (ASAB), National University of Sciences & Technology (NUST), Islamabad, Pakistan.
| | - Amna Jalil
- Atta ur Rahman School of Applied Biosciences (ASAB), National University of Sciences & Technology (NUST), Islamabad, Pakistan.
| | - Tahir Ahmed
- Atta ur Rahman School of Applied Biosciences (ASAB), National University of Sciences & Technology (NUST), Islamabad, Pakistan.
| | - Afra Rahman
- Atta ur Rahman School of Applied Biosciences (ASAB), National University of Sciences & Technology (NUST), Islamabad, Pakistan.
| | - Nawal Dawood
- Atta ur Rahman School of Applied Biosciences (ASAB), National University of Sciences & Technology (NUST), Islamabad, Pakistan.
| | - Ghulam Haider
- Atta ur Rahman School of Applied Biosciences (ASAB), National University of Sciences & Technology (NUST), Islamabad, Pakistan.
| | | | - Leon Rostock
- Institute of Pharmacy, Pharmaceutical Biology, University of Greifswald, Germany.
| | - Sebastian Guenther
- Institute of Pharmacy, Pharmaceutical Biology, University of Greifswald, Germany.
| | - Katharina Schaufler
- Institute of Pharmacy, Pharmaceutical Microbiology, University of Greifswald, Germany; Institute of infection medicine, Kiel University, Germany.
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Eisenhardt KMH, Remes B, Grützner J, Spanka DT, Jäger A, Klug G. A Complex Network of Sigma Factors and sRNA StsR Regulates Stress Responses in R. sphaeroides. Int J Mol Sci 2021; 22:ijms22147557. [PMID: 34299177 PMCID: PMC8307010 DOI: 10.3390/ijms22147557] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Revised: 07/01/2021] [Accepted: 07/09/2021] [Indexed: 11/16/2022] Open
Abstract
Adaptation of bacteria to a changing environment is often accompanied by remodeling of the transcriptome. In the facultative phototroph Rhodobacter sphaeroides the alternative sigma factors RpoE, RpoHI and RpoHII play an important role in a variety of stress responses, including heat, oxidative stress and nutrient limitation. Photooxidative stress caused by the simultaneous presence of chlorophylls, light and oxygen is a special challenge for phototrophic organisms. Like alternative sigma factors, several non-coding sRNAs have important roles in the defense against photooxidative stress. RNAseq-based transcriptome data pointed to an influence of the stationary phase-induced StsR sRNA on levels of mRNAs and sRNAs with a role in the photooxidative stress response. Furthermore, StsR also affects expression of photosynthesis genes and of genes for regulators of photosynthesis genes. In vivo and in vitro interaction studies revealed that StsR, that is under control of the RpoHI and RpoHII sigma factors, targets rpoE mRNA and affects its abundance by altering its stability. RpoE regulates expression of the rpoHII gene and, consequently, expression of stsR. These data provide new insights into a complex regulatory network of protein regulators and sRNAs involved in defense against photooxidative stress and the regulation of photosynthesis genes.
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Fasnacht M, Polacek N. Oxidative Stress in Bacteria and the Central Dogma of Molecular Biology. Front Mol Biosci 2021; 8:671037. [PMID: 34041267 PMCID: PMC8141631 DOI: 10.3389/fmolb.2021.671037] [Citation(s) in RCA: 83] [Impact Index Per Article: 27.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Accepted: 04/26/2021] [Indexed: 11/13/2022] Open
Abstract
Ever since the "great oxidation event," Earth's cellular life forms had to cope with the danger of reactive oxygen species (ROS) affecting the integrity of biomolecules and hampering cellular metabolism circuits. Consequently, increasing ROS levels in the biosphere represented growing stress levels and thus shaped the evolution of species. Whether the ROS were produced endogenously or exogenously, different systems evolved to remove the ROS and repair the damage they inflicted. If ROS outweigh the cell's capacity to remove the threat, we speak of oxidative stress. The injuries through oxidative stress in cells are diverse. This article reviews the damage oxidative stress imposes on the different steps of the central dogma of molecular biology in bacteria, focusing in particular on the RNA machines involved in transcription and translation.
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Affiliation(s)
- Michel Fasnacht
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Bern, Switzerland.,Graduate School for Cellular and Biomedical Sciences, University of Bern, Bern, Switzerland
| | - Norbert Polacek
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Bern, Switzerland
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Grützner J, Billenkamp F, Spanka DT, Rick T, Monzon V, Förstner KU, Klug G. The small DUF1127 protein CcaF1 from Rhodobacter sphaeroides is an RNA-binding protein involved in sRNA maturation and RNA turnover. Nucleic Acids Res 2021; 49:3003-3019. [PMID: 33706375 PMCID: PMC8034643 DOI: 10.1093/nar/gkab146] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Revised: 02/10/2021] [Accepted: 02/26/2021] [Indexed: 12/16/2022] Open
Abstract
Many different protein domains are conserved among numerous species, but their function remains obscure. Proteins with DUF1127 domains number >17 000 in current databases, but a biological function has not yet been assigned to any of them. They are mostly found in alpha- and gammaproteobacteria, some of them plant and animal pathogens, symbionts or species used in industrial applications. Bioinformatic analyses revealed similarity of the DUF1127 domain of bacterial proteins to the RNA binding domain of eukaryotic Smaug proteins that are involved in RNA turnover and have a role in development from Drosophila to mammals. This study demonstrates that the 71 amino acid DUF1127 protein CcaF1 from the alphaproteobacterium Rhodobacter sphaeroides participates in maturation of the CcsR sRNAs that are processed from the 3' UTR of the ccaF mRNA and have a role in the oxidative stress defense. CcaF1 binds to many cellular RNAs of different type, several mRNAs with a function in cysteine / methionine / sulfur metabolism. It affects the stability of the CcsR RNAs and other non-coding RNAs and mRNAs. Thus, the widely distributed DUF1127 domain can mediate RNA-binding, affect stability of its binding partners and consequently modulate the bacterial transcriptome, thereby influencing different physiological processes.
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Affiliation(s)
- Julian Grützner
- Institute of Microbiology and Molecular Biology, Justus Liebig University Giessen, IFZ, Heinrich-Buff-Ring 26–32, D-35292 Giessen, Germany
| | - Fabian Billenkamp
- Institute of Microbiology and Molecular Biology, Justus Liebig University Giessen, IFZ, Heinrich-Buff-Ring 26–32, D-35292 Giessen, Germany
- Institute of Animal Nutrition, Friedrich Loeffler Institute, Bundesalle 37, D-38116 Braunschweig, Germany
| | - Daniel-Timon Spanka
- Institute of Microbiology and Molecular Biology, Justus Liebig University Giessen, IFZ, Heinrich-Buff-Ring 26–32, D-35292 Giessen, Germany
| | - Tim Rick
- Institute of Microbiology and Molecular Biology, Justus Liebig University Giessen, IFZ, Heinrich-Buff-Ring 26–32, D-35292 Giessen, Germany
| | | | - Konrad U Förstner
- ZB MED-Information Center of Life Science, Germany
- Institute of Information Science, TH Köln, University of Applied Science, Gustav-Heinemann-Ufer 54, D-50968 Köln, Cologne, Germany
| | - Gabriele Klug
- Institute of Microbiology and Molecular Biology, Justus Liebig University Giessen, IFZ, Heinrich-Buff-Ring 26–32, D-35292 Giessen, Germany
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Sánchez-Ortiz VJ, Domenzain C, Poggio S, Dreyfus G, Camarena L. The periplasmic component of the DctPQM TRAP-transporter is part of the DctS/DctR sensory pathway in Rhodobacter sphaeroides. MICROBIOLOGY-SGM 2021; 167. [PMID: 33620307 DOI: 10.1099/mic.0.001037] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Rhodobacter sphaeroides can use C4-dicarboxylic acids to grow heterotrophically or photoheterotropically, and it was previously demonstrated in Rhodobacter capsulatus that the DctPQM transporter system is essential to support growth using these organic acids under heterotrophic but not under photoheterotrophic conditions. In this work we show that in R. sphaeroides this transporter system is essential for photoheterotrophic and heterotrophic growth, when C4-dicarboxylic acids are used as a carbon source. We also found that over-expression of dctPQM is detrimental for photoheterotrophic growth in the presence of succinic acid in the culture medium. In agreement with this, we observed a reduction of the dctPQM promoter activity in cells growing under these conditions, indicating that the amount of DctPQM needs to be reduced under photoheterotrophic growth. It has been reported that the two-component system DctS and DctR activates the expression of dctPQM. Our results demonstrate that in the absence of DctR, dctPQM is still expressed albeit at a low level. In this work, we have found that the periplasmic component of the transporter system, DctP, has a role in both transport and in signalling the DctS/DctR two-component system.
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Affiliation(s)
- Veronica Jazmín Sánchez-Ortiz
- Posgrado en Ciencias Biológicas, Instituto de Investigaciones Biomédicas, Universidad Nacional Autonoma de México, Mexico.,Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico
| | - Clelia Domenzain
- Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico
| | - Sebastian Poggio
- Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico
| | - Georges Dreyfus
- Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico
| | - Laura Camarena
- Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico
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Spanka DT, Reuscher CM, Klug G. Impact of PNPase on the transcriptome of Rhodobacter sphaeroides and its cooperation with RNase III and RNase E. BMC Genomics 2021; 22:106. [PMID: 33549057 PMCID: PMC7866481 DOI: 10.1186/s12864-021-07409-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Accepted: 01/26/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The polynucleotide phosphorylase (PNPase) is conserved among both Gram-positive and Gram-negative bacteria. As a core part of the Escherichia coli degradosome, PNPase is involved in maintaining proper RNA levels within the bacterial cell. It plays a major role in RNA homeostasis and decay by acting as a 3'-to-5' exoribonuclease. Furthermore, PNPase can catalyze the reverse reaction by elongating RNA molecules in 5'-to-3' end direction which has a destabilizing effect on the prolonged RNA molecule. RNA degradation is often initiated by an endonucleolytic cleavage, followed by exoribonucleolytic decay from the new 3' end. RESULTS The PNPase mutant from the facultative phototrophic Rhodobacter sphaeroides exhibits several phenotypical characteristics, including diminished adaption to low temperature, reduced resistance to organic peroxide induced stress and altered growth behavior. The transcriptome composition differs in the pnp mutant strain, resulting in a decreased abundance of most tRNAs and rRNAs. In addition, PNPase has a major influence on the half-lives of several regulatory sRNAs and can have both a stabilizing or a destabilizing effect. Moreover, we globally identified and compared differential RNA 3' ends in RNA NGS sequencing data obtained from PNPase, RNase E and RNase III mutants for the first time in a Gram-negative organism. The genome wide RNA 3' end analysis revealed that 885 3' ends are degraded by PNPase. A fair percentage of these RNA 3' ends was also identified at the same genomic position in RNase E or RNase III mutant strains. CONCLUSION The PNPase has a major influence on RNA processing and maturation and thus modulates the transcriptome of R. sphaeroides. This includes sRNAs, emphasizing the role of PNPase in cellular homeostasis and its importance in regulatory networks. The global 3' end analysis indicates a sequential RNA processing: 5.9% of all RNase E-dependent and 9.7% of all RNase III-dependent RNA 3' ends are subsequently degraded by PNPase. Moreover, we provide a modular pipeline which greatly facilitates the identification of RNA 5'/3' ends. It is publicly available on GitHub and is distributed under ICS license.
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Affiliation(s)
- Daniel-Timon Spanka
- Institute of Microbiology and Molecular Biology, Justus Liebig University Giessen, IFZ, Giessen, Germany
| | - Carina Maria Reuscher
- Institute of Microbiology and Molecular Biology, Justus Liebig University Giessen, IFZ, Giessen, Germany
| | - Gabriele Klug
- Institute of Microbiology and Molecular Biology, Justus Liebig University Giessen, IFZ, Giessen, Germany.
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Adaptation to Photooxidative Stress: Common and Special Strategies of the Alphaproteobacteria Rhodobacter sphaeroides and Rhodobacter capsulatus. Microorganisms 2020; 8:microorganisms8020283. [PMID: 32093084 PMCID: PMC7074977 DOI: 10.3390/microorganisms8020283] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Revised: 02/10/2020] [Accepted: 02/13/2020] [Indexed: 12/20/2022] Open
Abstract
Photosynthetic bacteria have to deal with the risk of photooxidative stress that occurs in presence of light and oxygen due to the photosensitizing activity of (bacterio-) chlorophylls. Facultative phototrophs of the genus Rhodobacter adapt the formation of photosynthetic complexes to oxygen and light conditions, but cannot completely avoid this stress if environmental conditions suddenly change. R. capsulatus has a stronger pigmentation and faster switches to phototrophic growth than R. sphaeroides. However, its photooxidative stress response has not been investigated. Here, we compare both species by transcriptomics and proteomics, revealing that proteins involved in oxidation-reduction processes, DNA, and protein damage repair play pivotal roles. These functions are likely universal to many phototrophs. Furthermore, the alternative sigma factors RpoE and RpoHII are induced in both species, even though the genetic localization of the rpoE gene, the RpoE protein itself, and probably its regulon, are different. Despite sharing the same habitats, our findings also suggest individual strategies. The crtIB-tspO operon, encoding proteins for biosynthesis of carotenoid precursors and a regulator of photosynthesis, and cbiX, encoding a putative ferrochelatase, are induced in R. capsulatus. This specific response might support adaptation by maintaining high carotenoid-to-bacteriochlorophyll ratios and preventing the accumulation of porphyrin-derived photosensitizers.
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18
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McIntosh M, Eisenhardt K, Remes B, Konzer A, Klug G. Adaptation of the Alphaproteobacterium Rhodobacter sphaeroides to stationary phase. Environ Microbiol 2019; 21:4425-4445. [PMID: 31579997 DOI: 10.1111/1462-2920.14809] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2018] [Revised: 08/30/2019] [Accepted: 09/18/2019] [Indexed: 12/20/2022]
Abstract
Exhaustion of nutritional resources stimulates bacterial populations to adapt their growth behaviour. General mechanisms are known to facilitate this adaptation by sensing the environmental change and coordinating gene expression. However, the existence of such mechanisms among the Alphaproteobacteria remains unclear. This study focusses on global changes in transcript levels during growth under carbon-limiting conditions in a model Alphaproteobacterium, Rhodobacter sphaeroides, a metabolically diverse organism capable of multiple modes of growth including aerobic and anaerobic respiration, anaerobic anoxygenic photosynthesis and fermentation. We identified genes that showed changed transcript levels independently of oxygen levels during the adaptation to stationary phase. We selected a subset of these genes and subjected them to mutational analysis, including genes predicted to be involved in manganese uptake, polyhydroxybutyrate production and quorum sensing and an alternative sigma factor. Although these genes have not been previously associated with the adaptation to stationary phase, we found that all were important to varying degrees. We conclude that while R. sphaeroides appears to lack a rpoS-like master regulator of stationary phase adaptation, this adaptation is nonetheless enabled through the impact of multiple genes, each responding to environmental conditions and contributing to the adaptation to stationary phase.
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Affiliation(s)
- Matthew McIntosh
- Institut für Mikrobiologie und Molekularbiologie, IFZ, Justus-Liebig-Universität, 35392, Giessen, Germany
| | - Katrin Eisenhardt
- Institut für Mikrobiologie und Molekularbiologie, IFZ, Justus-Liebig-Universität, 35392, Giessen, Germany
| | - Bernhard Remes
- Institut für Mikrobiologie und Molekularbiologie, IFZ, Justus-Liebig-Universität, 35392, Giessen, Germany
| | - Anne Konzer
- Biomolecular Mass Spectrometry, Max-Planck-Institute for Heart and Lung Research, Bad Nauheim, Germany
| | - Gabriele Klug
- Institut für Mikrobiologie und Molekularbiologie, IFZ, Justus-Liebig-Universität, 35392, Giessen, Germany
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19
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Zhao Z, Peng T, Oh JI, Glaeser J, Weber L, Li Q, Klug G. A response regulator of the OmpR family is part of the regulatory network controlling the oxidative stress response of Rhodobacter sphaeroides. ENVIRONMENTAL MICROBIOLOGY REPORTS 2019; 11:118-128. [PMID: 30451391 DOI: 10.1111/1758-2229.12718] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2017] [Accepted: 11/12/2018] [Indexed: 06/09/2023]
Abstract
As a free-living bacterium Rhodobacter sphaeroides needs to respond to many environmental stresses. Oxidative stress, membrane stress or heat stress induce the ompR-1 gene encoding a protein of the OmpR family. Overexpression of OmpR-1 results in increased resistance to organic peroxides and diamide. Our data demonstrate that OmpR-1 positively affects expression of several sRNAs with an established role in R. sphaeroides stress defences and negatively affects the promoter of the rpoHI gene. The RpoHI sigma factor has a main role in the activation of many stress responses. Thus OmpR-1 has a balancing effect on the activation of the RpoHI regulon. We present a model with OmpR-1 as part of a regulatory network controlling stress defences in R. sphaeroides.
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Affiliation(s)
- Zhiping Zhao
- Institut für Mikrobiologie und Molekularbiologie, Interdiziplinäres Forschungszentrum, Justus-Liebig-Universität Giessen, Giessen, Germany
- Department of Pharmaceutical Engineering, Sichuan University of Science and Engineering, Zigong, China
| | | | - Jeong-Il Oh
- Department of Microbiology, Pusan National University, Busan, South Korea
| | - Jens Glaeser
- Institut für Mikrobiologie und Molekularbiologie, Interdiziplinäres Forschungszentrum, Justus-Liebig-Universität Giessen, Giessen, Germany
| | - Lennart Weber
- Institut für Mikrobiologie und Molekularbiologie, Interdiziplinäres Forschungszentrum, Justus-Liebig-Universität Giessen, Giessen, Germany
| | - Qingfeng Li
- Institut für Mikrobiologie und Molekularbiologie, Interdiziplinäres Forschungszentrum, Justus-Liebig-Universität Giessen, Giessen, Germany
| | - Gabriele Klug
- Institut für Mikrobiologie und Molekularbiologie, Interdiziplinäres Forschungszentrum, Justus-Liebig-Universität Giessen, Giessen, Germany
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20
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Peng T, Kan J, Lun J, Hu Z. Identification of novel sRNAs involved in oxidative stress response in the fish pathogen Vibrio alginolyticus by transcriptome analysis. JOURNAL OF FISH DISEASES 2019; 42:277-291. [PMID: 30488970 DOI: 10.1111/jfd.12926] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Revised: 10/23/2018] [Accepted: 10/25/2018] [Indexed: 06/09/2023]
Abstract
Vibrio alginolyticus as an important pathogen in aquaculture can encounter the oxidative stress produced by the immune system during infection. Previous studies showed that sRNAs have important functions in response to oxidative stress in bacteria; however, less of sRNAs related to oxidative stress response were identified in V. alginolyticus. In this study, a total of 749 novel sRNAs were identified by RNA sequencing; among them, 128 sRNAs were up- or downregulated in response to oxidative stress. In addition, 1,870 genes exhibited variation on mRNA levels in oxidative stress response. By analysing the target genes of the sRNAs, we concluded that these sRNAs could regulate expressions of genes responsible for iron transport, catalase, GSH-dependent defence system, electron transferred and stress response. Moreover, the functions of the sRNAs are also seemed related to the pathogenicity in V. alginolyticus. Based on the results, we constructed the oxidative stress model in V. alginolyticus. This study provides us the first outlook of sRNAs function in oxidative stress response in V. alginolyticus. Furthermore, this study can help us to prevent and control this important opportunistic pathogen in aquaculture.
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Affiliation(s)
- Tao Peng
- Department of Biology, Shantou University, Shantou, China
| | - Jie Kan
- Department of Biology, Shantou University, Shantou, China
| | - Jingsheng Lun
- Department of Biology, Shantou University, Shantou, China
| | - Zhong Hu
- Department of Biology, Shantou University, Shantou, China
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21
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Gupta D, Mohammed M, Mekala LP, Chintalapati S, Chintalapati VR. iTRAQ-based quantitative proteomics reveals insights into metabolic and molecular responses of glucose-grown cells of Rubrivivax benzoatilyticus JA2. J Proteomics 2018; 194:49-59. [PMID: 30597313 DOI: 10.1016/j.jprot.2018.12.027] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2018] [Revised: 12/19/2018] [Accepted: 12/26/2018] [Indexed: 01/28/2023]
Abstract
Anoxygenic photosynthetic bacteria thrive under diverse habitats utilising an extended range of inorganic/organic compounds under different growth modes. Although they display incredible metabolic flexibility, their responses and adaptations to changing carbon regimes is largely unexplored. In the present study, we employed iTRAQ-based global proteomic profiling and physiological studies to uncover the adaptive strategies of a phototrophic bacterium, Rubrivivax benzoatilyticus JA2 to glucose. Strain JA2 displayed altered growth rates, reduced cell size and progressive loss of pigmentation when grown on glucose compared to malate under photoheterotrophic condition. A ten-fold increase in the saturated to unsaturated fatty acid ratio of glucose-grown cells indicates a possible membrane adaptation. Proteomic profiling revealed extensive metabolic remodelling in the glucose-grown cells wherein signal-transduction, selective-transcription, DNA-repair, transport and protein quality control processes were up-regulated to cope with the changing milieu. Proteins involved in DNA replication, translation, electron-transport, photosynthetic machinery were down-regulated possibly to conserve the energy. Glycolysis/gluconeogenesis, TCA cycle and pigment biosynthesis were also down-regulated. The cell has activated alternative energy metabolic pathways viz., fatty acid β-oxidation, glyoxylate, acetate-switch and Entner-Doudoroff pathways. Overall, the present study deciphered the molecular/metabolic events associated with glucose-grown cells of strain JA2 and also unraveled how a carbon source modulates the metabolic phenotypes. SIGNIFICANCE: Anoxygenic photosynthetic bacteria (APB) exhibit incredible metabolic flexibility leading to diverse phenotypes. They thrive under diverse habitat using an array of inorganic/organic compounds as carbon sources, yet their metabolic adaptation to varying carbon regime is mostly unexplored. Present study uncovered the proteomic insights of the cellular responses of strain JA2 to changing carbon sources viz. malate and glucose under photoheterotrophic conditions. Our study suggests that carbon source can also determine the metabolic fate of the cells and reshape the energy dynamics of APB. Here, for the first time study highlighted the plausible carbon source (glucose) mediated regulation of photosynthesis in APB. The study sheds light on the plausible cellular events and adaptive metabolic strategies employed by strain JA2 in presence of non-preferred carbon source. It also revealed new insights into the metabolic plasticity of APB to the changing milieu.
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Affiliation(s)
- Deepshikha Gupta
- Department of Plant Sciences, P.O. Central University, University of Hyderabad, Hyderabad 500046, India
| | - Mujahid Mohammed
- Department of Plant Sciences, P.O. Central University, University of Hyderabad, Hyderabad 500046, India
| | - Lakshmi Prasuna Mekala
- Department of Plant Sciences, P.O. Central University, University of Hyderabad, Hyderabad 500046, India
| | - Sasikala Chintalapati
- Bacterial Discovery Laboratory, Centre for Environment, IST, JNT University Hyderabad, Kukatpally, Hyderabad 500085, India
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Eisenhardt KMH, Reuscher CM, Klug G. PcrX, an sRNA derived from the 3'- UTR of the Rhodobacter sphaeroides puf operon modulates expression of puf genes encoding proteins of the bacterial photosynthetic apparatus. Mol Microbiol 2018; 110:325-334. [PMID: 29995316 DOI: 10.1111/mmi.14076] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/03/2018] [Indexed: 11/30/2022]
Abstract
Facultative phototrophic bacteria like Rhodobacter sphaeroides can produce ATP by anoxygenic photosynthesis, which is of advantage under conditions with limiting oxygen. However, the simultaneous presence of pigments, light and oxygen leads to the generation of harmful singlet oxygen. In order to avoid this stress situation, the formation of photosynthetic complexes is tightly regulated by light and oxygen signals. In a complex regulatory network several regulatory proteins and the small non-coding RNA PcrZ contribute to the balanced expression of photosynthesis genes. With PcrX this study identifies a second sRNA that is part of this network. The puf operon encodes pigment binding proteins of the light-harvesting I complex (PufBA) and of the reaction center (PufLM), a protein regulating porphyrin flux (PufQ), and a scaffolding protein (PufX). The PcrX sRNA is derived from the 3' UTR of the puf operon mRNA by RNase E-mediated cleavage. It targets the pufX mRNA segment, reduces the half-life of the pufBALMX mRNA and as a consequence affects the level of photosynthetic complexes. By its action PcrX counteracts the increased expression of photosynthesis genes that is mediated by protein regulators and is thus involved in balancing the formation of photosynthetic complexes in response to external stimuli.
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Affiliation(s)
- Katrin M H Eisenhardt
- Institut für Mikrobiologie und Molekularbiologie, Justus Liebig Universität Giessen, IFZ, Giessen, Germany
| | - Carina M Reuscher
- Institut für Mikrobiologie und Molekularbiologie, Justus Liebig Universität Giessen, IFZ, Giessen, Germany
| | - Gabriele Klug
- Institut für Mikrobiologie und Molekularbiologie, Justus Liebig Universität Giessen, IFZ, Giessen, Germany
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23
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Förstner KU, Reuscher CM, Haberzettl K, Weber L, Klug G. RNase E cleavage shapes the transcriptome ofRhodobacter sphaeroidesand strongly impacts phototrophic growth. Life Sci Alliance 2018; 1:e201800080. [PMID: 30456366 PMCID: PMC6238624 DOI: 10.26508/lsa.201800080] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2018] [Revised: 07/13/2018] [Accepted: 07/13/2018] [Indexed: 11/24/2022] Open
Abstract
This study identifies the cleavage sites of the endoribonuclease RNase E in the Rhodobacter sphaeroides transcriptome and demonstrates its effect on oxidative stress resistance and phototrophic growth. Bacteria adapt to changing environmental conditions by rapid changes in their transcriptome. This is achieved not only by adjusting rates of transcription but also by processing and degradation of RNAs. We applied TIER-Seq (transiently inactivating an endoribonuclease followed by RNA-Seq) for the transcriptome-wide identification of RNase E cleavage sites and of 5′ RNA ends, which are enriched when RNase E activity is reduced in Rhodobacter sphaeroides. These results reveal the importance of RNase E for the maturation and turnover of mRNAs, rRNAs, and sRNAs in this guanine-cytosine-rich α-proteobacterium, some of the latter have well-described functions in the oxidative stress response. In agreement with this, a role of RNase E in the oxidative stress response is demonstrated. A remarkably strong phenotype of a mutant with reduced RNase E activity was observed regarding the formation of photosynthetic complexes and phototrophic growth, whereas there was no effect on chemotrophic growth.
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Affiliation(s)
- Konrad U Förstner
- German National Library of Medicine—Information Center for Life Sciences, Cologne, Germany
- Technical University of Cologne, Faculty for Information and Communication Sciences, Cologne, Germany
- Core Unit Systems Medicine, Institutes of Molecular Infection Biology, University of Würzburg, Würzburg, Germany
- Correspondence:
| | - Carina M Reuscher
- Institut für Mikrobiologie und Molekularbiologie, Interdisciplinary Research Center for Biosystems, Universität Giessen, Giessen, Germany
| | - Kerstin Haberzettl
- Institut für Mikrobiologie und Molekularbiologie, Interdisciplinary Research Center for Biosystems, Universität Giessen, Giessen, Germany
| | - Lennart Weber
- Institut für Mikrobiologie und Molekularbiologie, Interdisciplinary Research Center for Biosystems, Universität Giessen, Giessen, Germany
| | - Gabriele Klug
- Institut für Mikrobiologie und Molekularbiologie, Interdisciplinary Research Center for Biosystems, Universität Giessen, Giessen, Germany
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24
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Elkina D, Weber L, Lechner M, Burenina O, Weisert A, Kubareva E, Hartmann RK, Klug G. 6S RNA in Rhodobacter sphaeroides: 6S RNA and pRNA transcript levels peak in late exponential phase and gene deletion causes a high salt stress phenotype. RNA Biol 2017; 14:1627-1637. [PMID: 28692405 DOI: 10.1080/15476286.2017.1342933] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
Abstract
The function of 6S RNA, a global regulator of transcription, was studied in the photosynthetic α-proteobacterium Rhodobacter sphaeroides. The cellular levels of R. sphaeroides 6S RNA peak toward the transition to stationary phase and strongly decrease during extended stationary phase. The synthesis of so-called product RNA transcripts (mainly 12-16-mers) on 6S RNA as template by RNA polymerase was found to be highest in late exponential phase. Product RNA ≥ 13-mers are expected to trigger the dissociation of 6S RNA:RNA polymerase complexes. A 6S RNA deletion in R. sphaeroides had no impact on growth under various metabolic and oxidative stress conditions (with the possible exception of tert-butyl hydroperoxide stress). However, the 6S RNA knockout resulted in a robust growth defect under high salt stress (0.25 M NaCl). Remarkably, the sspA gene encoding the putative salt stress-induced membrane protein SspA and located immediately downstream of the 6S RNA (ssrS) gene on the antisense strand was expressed at elevated levels in the ΔssrS strain when grown in the presence of 250 mM NaCl.
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Affiliation(s)
- Daria Elkina
- a Chemistry Department and A.N. Belozersky Institute of Physico-Chemical Biology , M.V. Lomonosov Moscow State University , Leninskie Gory 1, Moscow , Russia
| | - Lennart Weber
- b Institut für Mikrobiologie und Molekularbiologie, Justus-Liebig-University-Gießen, Heinrich-Buff-Ring 26-32 , Gießen , Germany
| | - Marcus Lechner
- c Institut für Pharmazeutische Chemie, Philipps-Universität Marburg, Marbacher Weg 6 , Marburg , Germany ; Skolkovo Institute for Science and Technology , Skoltech, Moscow
| | - Olga Burenina
- a Chemistry Department and A.N. Belozersky Institute of Physico-Chemical Biology , M.V. Lomonosov Moscow State University , Leninskie Gory 1, Moscow , Russia
| | - Andrea Weisert
- b Institut für Mikrobiologie und Molekularbiologie, Justus-Liebig-University-Gießen, Heinrich-Buff-Ring 26-32 , Gießen , Germany
| | - Elena Kubareva
- a Chemistry Department and A.N. Belozersky Institute of Physico-Chemical Biology , M.V. Lomonosov Moscow State University , Leninskie Gory 1, Moscow , Russia
| | - Roland K Hartmann
- c Institut für Pharmazeutische Chemie, Philipps-Universität Marburg, Marbacher Weg 6 , Marburg , Germany ; Skolkovo Institute for Science and Technology , Skoltech, Moscow
| | - Gabriele Klug
- b Institut für Mikrobiologie und Molekularbiologie, Justus-Liebig-University-Gießen, Heinrich-Buff-Ring 26-32 , Gießen , Germany
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An RpoHI-Dependent Response Promotes Outgrowth after Extended Stationary Phase in the Alphaproteobacterium Rhodobacter sphaeroides. J Bacteriol 2017; 199:JB.00249-17. [PMID: 28507242 DOI: 10.1128/jb.00249-17] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2017] [Accepted: 05/05/2017] [Indexed: 12/31/2022] Open
Abstract
Under unfavorable growth conditions, bacteria enter stationary phase and can maintain cell viability over prolonged periods with no increase in cell number. To obtain insights into the regulatory mechanisms that allow bacteria to resume growth when conditions become favorable again (outgrowth), we performed global transcriptome analyses at different stages of growth for the alphaproteobacterium Rhodobacter sphaeroides The majority of genes were not differentially expressed across growth phases. After a short stationary phase (about 20 h after growth starts to slow down), only 7% of the genes showed altered expression (fold change of >1.6 or less than -1.6, corresponding to a log2 fold change of >0.65 or less than -0.65, respectively) compared to expression at exponential phase. Outgrowth induced a distinct response in gene expression which was strongly influenced by the length of the preceding stationary phase. After a long stationary phase (about 64 h after growth starts to slow down), a much larger number of genes (15.1%) was induced in outgrowth than after a short stationary phase (1.7%). Many of those genes are known members of the RpoHI/RpoHII regulons and have established functions in stress responses. A main effect of RpoHI on the transcriptome in outgrowth after a long stationary phase was confirmed. Growth experiments with mutant strains further support an important function in outgrowth after prolonged stationary phase for the RpoHI and RpoHII sigma factors.IMPORTANCE In natural environments, the growth of bacteria is limited mostly by lack of nutrients or other unfavorable conditions. It is important for bacterial populations to efficiently resume growth after being in stationary phase, which may last for long periods. Most previous studies on growth-phase-dependent gene expression did not address outgrowth after stationary phase. This study on growth-phase-dependent gene regulation in a model alphaproteobacterium reveals, for the first time, that the length of the stationary phase strongly impacts the transcriptome during outgrowth. The alternative sigma factors RpoHI and RpoHII, which are important regulators of stress responses in alphaproteobacteria, play a major role during outgrowth following prolonged stationary phase. These findings provide the first insight into the regulatory mechanisms enabling efficient outgrowth.
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Prasse D, Förstner KU, Jäger D, Backofen R, Schmitz RA. sRNA 154 a newly identified regulator of nitrogen fixation in Methanosarcina mazei strain Gö1. RNA Biol 2017; 14:1544-1558. [PMID: 28296572 DOI: 10.1080/15476286.2017.1306170] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
Abstract
Trans-encoded sRNA154 is exclusively expressed under nitrogen (N)-deficiency in Methanosarcina mazei strain Gö1. The sRNA154 deletion strain showed a significant decrease in growth under N-limitation, pointing toward a regulatory role of sRNA154 in N-metabolism. Aiming to elucidate its regulatory function we characterized sRNA154 by means of biochemical and genetic approaches. 24 homologs of sRNA154 were identified in recently reported draft genomes of Methanosarcina strains, demonstrating high conservation in sequence and predicted secondary structure with two highly conserved single stranded loops. Transcriptome studies of sRNA154 deletion mutants by an RNA-seq approach uncovered nifH- and nrpA-mRNA, encoding the α-subunit of nitrogenase and the transcriptional activator of the nitrogen fixation (nif)-operon, as potential targets besides other components of the N-metabolism. Furthermore, results obtained from stability, complementation and western blot analysis, as well as in silico target predictions combined with electrophoretic mobility shift-assays, argue for a stabilizing effect of sRNA154 on the polycistronic nif-mRNA and nrpA-mRNA by binding with both loops. Further identified N-related targets were studied, which demonstrates that translation initiation of glnA2-mRNA, encoding glutamine synthetase2, appears to be affected by sRNA154 masking the ribosome binding site, whereas glnA1-mRNA appears to be stabilized by sRNA154. Overall, we propose that sRNA154 has a crucial regulatory role in N-metabolism in M. mazei by stabilizing the polycistronic mRNA encoding nitrogenase and glnA1-mRNA, as well as allowing a feed forward regulation of nif-gene expression by stabilizing nrpA-mRNA. Consequently, sRNA154 represents the first archaeal sRNA, for which a positive posttranscriptional regulation is demonstrated as well as inhibition of translation initiation.
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Affiliation(s)
- Daniela Prasse
- a Institut für Allgemeine Mikrobiologie, Christian-Albrechts-Universität zu Kiel , Am Botanischen Garten 1-9, Kiel , Germany
| | - Konrad U Förstner
- b Zentrum für Infektionsforschung , Universität Würzburg , Josef Schneider-Str. 2/ Bau D15, Würzburg
| | - Dominik Jäger
- a Institut für Allgemeine Mikrobiologie, Christian-Albrechts-Universität zu Kiel , Am Botanischen Garten 1-9, Kiel , Germany
| | - Rolf Backofen
- c Institut für Informatik, Albert-Ludwigs-Universität zu Freiburg , Georges-Koehler-Allee, Freiburg , Germany
| | - Ruth A Schmitz
- a Institut für Allgemeine Mikrobiologie, Christian-Albrechts-Universität zu Kiel , Am Botanischen Garten 1-9, Kiel , Germany
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Colameco S, Elliot MA. Non-coding RNAs as antibiotic targets. Biochem Pharmacol 2016; 133:29-42. [PMID: 28012959 DOI: 10.1016/j.bcp.2016.12.015] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2016] [Accepted: 12/12/2016] [Indexed: 02/07/2023]
Abstract
Antibiotics inhibit a wide range of essential processes in the bacterial cell, including replication, transcription, translation and cell wall synthesis. In many instances, these antibiotics exert their effects through association with non-coding RNAs. This review highlights many classical antibiotic targets (e.g. rRNAs and the ribosome), explores a number of emerging targets (e.g. tRNAs, RNase P, riboswitches and small RNAs), and discusses the future directions and challenges associated with non-coding RNAs as antibiotic targets.
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Affiliation(s)
- Savannah Colameco
- Department of Biology and Institute for Infectious Disease Research, McMaster University, 1280 Main Street West, Hamilton, ON L8S 4K1, Canada
| | - Marie A Elliot
- Department of Biology and Institute for Infectious Disease Research, McMaster University, 1280 Main Street West, Hamilton, ON L8S 4K1, Canada.
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Weber L, Thoelken C, Volk M, Remes B, Lechner M, Klug G. The Conserved Dcw Gene Cluster of R. sphaeroides Is Preceded by an Uncommonly Extended 5' Leader Featuring the sRNA UpsM. PLoS One 2016; 11:e0165694. [PMID: 27802301 PMCID: PMC5089854 DOI: 10.1371/journal.pone.0165694] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2016] [Accepted: 10/17/2016] [Indexed: 11/18/2022] Open
Abstract
Cell division and cell wall synthesis mechanisms are similarly conserved among bacteria. Consequently some bacterial species have comparable sets of genes organized in the dcw (division andcellwall) gene cluster. Dcw genes, their regulation and their relative order within the cluster are outstandingly conserved among rod shaped and gram negative bacteria to ensure an efficient coordination of growth and division. A well studied representative is the dcw gene cluster of E. coli. The first promoter of the gene cluster (mraZ1p) gives rise to polycistronic transcripts containing a 38 nt long 5’ UTR followed by the first gene mraZ. Despite reported conservation we present evidence for a much longer 5’ UTR in the gram negative and rod shaped bacterium Rhodobacter sphaeroides and in the family of Rhodobacteraceae. This extended 268 nt long 5’ UTR comprises a Rho independent terminator, which in case of termination gives rise to a non-coding RNA (UpsM). This sRNA is conditionally cleaved by RNase E under stress conditions in an Hfq- and very likely target mRNA-dependent manner, implying its function in trans. These results raise the question for the regulatory function of this extended 5’ UTR. It might represent the rarely described case of a trans acting sRNA derived from a riboswitch with exclusive presence in the family of Rhodobacteraceae.
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Affiliation(s)
- Lennart Weber
- Institute of Microbiology and Molecular Biology, IFZ, Justus-Liebig-University Giessen, Giessen, Germany
| | - Clemens Thoelken
- Institute of Pharmaceutical Chemistry, Philipps-University Marburg, Marburg, Germany
| | - Marcel Volk
- Institute of Microbiology and Molecular Biology, IFZ, Justus-Liebig-University Giessen, Giessen, Germany
| | - Bernhard Remes
- Institute of Microbiology and Molecular Biology, IFZ, Justus-Liebig-University Giessen, Giessen, Germany
| | - Marcus Lechner
- Institute of Pharmaceutical Chemistry, Philipps-University Marburg, Marburg, Germany
| | - Gabriele Klug
- Institute of Microbiology and Molecular Biology, IFZ, Justus-Liebig-University Giessen, Giessen, Germany
- * E-mail:
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Müller KMH, Berghoff BA, Eisenhardt BD, Remes B, Klug G. Characteristics of Pos19 - A Small Coding RNA in the Oxidative Stress Response of Rhodobacter sphaeroides. PLoS One 2016; 11:e0163425. [PMID: 27669425 PMCID: PMC5036791 DOI: 10.1371/journal.pone.0163425] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2016] [Accepted: 09/08/2016] [Indexed: 02/07/2023] Open
Abstract
The phototrophic bacterium Rhodobacter sphaeroides induces several small RNAs (sRNAs) when singlet oxygen (1O2) levels are elevated, a situation also referred to as photo-oxidative stress. An RNA-seq study identified the RSs0019 sRNA, which is renamed Pos19 (photo-oxidative stress induced sRNA 19). Pos19 is part of the RpoE regulon and consequently induced upon 1O2 and peroxide stress. The 219 nt long Pos19 transcript contains a small open reading frame (sORF) of 150 nt, which is translated in vivo. Over-expression of Pos19 results in reduced mRNA levels for several genes, of which numerous are involved in sulfur metabolism. The negative effect on the potential targets is maintained even when translation of the sORF is abolished, arguing that regulation is entailed by the sRNA itself. Reporter studies further revealed that regulation of the most affected mRNA, namely RSP_0557, by Pos19 is Hfq-dependent. Direct binding of Pos19 to Hfq was shown by co-immunoprecipitation. Physiological experiments indicated Pos19 to be involved in the balance of glutathione biosynthesis. Moreover, a lack of Pos19 leads to elevated reactive oxygen species levels. Taken together our data identify the sRNA Pos19 as a coding sRNA with a distinct expression pattern and potential role under oxidative stress in the phototrophic bacterium R. sphaeroides.
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Affiliation(s)
- Katrin M. H. Müller
- Institut für Mikrobiologie und Molekularbiologie, Justus-Liebig-Universität, Heinrich-Buff-Ring 26, 35392, Giessen, Germany
| | - Bork A. Berghoff
- Institut für Mikrobiologie und Molekularbiologie, Justus-Liebig-Universität, Heinrich-Buff-Ring 26, 35392, Giessen, Germany
| | - Benjamin D. Eisenhardt
- Institut für Mikrobiologie und Molekularbiologie, Justus-Liebig-Universität, Heinrich-Buff-Ring 26, 35392, Giessen, Germany
| | - Bernhard Remes
- Institut für Mikrobiologie und Molekularbiologie, Justus-Liebig-Universität, Heinrich-Buff-Ring 26, 35392, Giessen, Germany
| | - Gabriele Klug
- Institut für Mikrobiologie und Molekularbiologie, Justus-Liebig-Universität, Heinrich-Buff-Ring 26, 35392, Giessen, Germany
- * E-mail:
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Peng T, Berghoff BA, Oh JI, Weber L, Schirmer J, Schwarz J, Glaeser J, Klug G. Regulation of a polyamine transporter by the conserved 3' UTR-derived sRNA SorX confers resistance to singlet oxygen and organic hydroperoxides in Rhodobacter sphaeroides. RNA Biol 2016; 13:988-999. [PMID: 27420112 DOI: 10.1080/15476286.2016.1212152] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Singlet oxygen is generated by bacteriochlorophylls when light and oxygen are simultaneously present in Rhodobacter sphaeroides. Singlet oxygen triggers a specific response that is partly regulated by the alternative sigma factor RpoHI/HII. The sRNA RSs2461 has previously been identified as an RpoHI/HII-dependent sRNA and is derived from the 3' UTR of the mRNA for an OmpR-type transcriptional regulator. Similar to the RpoHI/HII-dependent CcsR and SorY sRNAs, RSs2461 affects the resistance of R. sphaeroides against singlet oxygen and was therefore renamed here SorX. Furthermore, SorX has a strong impact on resistance against organic hydroperoxides that usually occur as secondary damages downstream of singlet oxygen. The 75-nt SorX 3' fragment, which is generated by RNase E cleavage and highly conserved among related species, represents the functional entity. A target search identified potA mRNA, which encodes a subunit of a polyamine transporter, as a direct SorX target and stress resistance via SorX could be linked to potA. The PotABCD transporter is an uptake system for spermidine in E. coli. While spermidine is generally described as beneficial during oxidative stress, we observed significantly increased sensitivity of R. sphaeroides to organic hydroperoxides in the presence of spermidine. We therefore propose that the diminished import of spermidine, due to down-regulation of potA by SorX, counteracts oxidative stress. Together with results from other studies this underlines the importance of regulated transport to bacterial stress defense.
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Affiliation(s)
- Tao Peng
- a Institut für Mikrobiologie und Molekularbiologie, IFZ, Universität Giessen , Giessen , Germany
| | - Bork A Berghoff
- a Institut für Mikrobiologie und Molekularbiologie, IFZ, Universität Giessen , Giessen , Germany
| | - Jeong-Il Oh
- b Department of Microbiology , Pusan National University , Busan , Korea
| | - Lennart Weber
- a Institut für Mikrobiologie und Molekularbiologie, IFZ, Universität Giessen , Giessen , Germany
| | - Jasmin Schirmer
- a Institut für Mikrobiologie und Molekularbiologie, IFZ, Universität Giessen , Giessen , Germany
| | - Johannes Schwarz
- a Institut für Mikrobiologie und Molekularbiologie, IFZ, Universität Giessen , Giessen , Germany
| | - Jens Glaeser
- a Institut für Mikrobiologie und Molekularbiologie, IFZ, Universität Giessen , Giessen , Germany
| | - Gabriele Klug
- a Institut für Mikrobiologie und Molekularbiologie, IFZ, Universität Giessen , Giessen , Germany
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Tuning fresh: radiation through rewiring of central metabolism in streamlined bacteria. ISME JOURNAL 2016; 10:1902-14. [PMID: 26784354 PMCID: PMC5029164 DOI: 10.1038/ismej.2015.260] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/28/2015] [Revised: 11/24/2015] [Accepted: 12/10/2015] [Indexed: 11/08/2022]
Abstract
Most free-living planktonic cells are streamlined and in spite of their limitations in functional flexibility, their vast populations have radiated into a wide range of aquatic habitats. Here we compared the metabolic potential of subgroups in the Alphaproteobacteria lineage SAR11 adapted to marine and freshwater habitats. Our results suggest that the successful leap from marine to freshwaters in SAR11 was accompanied by a loss of several carbon degradation pathways and a rewiring of the central metabolism. Examples for these are C1 and methylated compounds degradation pathways, the Entner–Doudouroff pathway, the glyoxylate shunt and anapleuretic carbon fixation being absent from the freshwater genomes. Evolutionary reconstructions further suggest that the metabolic modules making up these important freshwater metabolic traits were already present in the gene pool of ancestral marine SAR11 populations. The loss of the glyoxylate shunt had already occurred in the common ancestor of the freshwater subgroup and its closest marine relatives, suggesting that the adaptation to freshwater was a gradual process. Furthermore, our results indicate rapid evolution of TRAP transporters in the freshwater clade involved in the uptake of low molecular weight carboxylic acids. We propose that such gradual tuning of metabolic pathways and transporters toward locally available organic substrates is linked to the formation of subgroups within the SAR11 clade and that this process was critical for the freshwater clade to find and fix an adaptive phenotype.
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