1
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Arbour CA, Nagar R, Bernstein HM, Ghosh S, Al-Sammarraie Y, Dorfmueller HC, Ferguson MAJ, Stanley-Wall NR, Imperiali B. Defining early steps in Bacillus subtilis biofilm biosynthesis. mBio 2023; 14:e0094823. [PMID: 37650625 PMCID: PMC10653937 DOI: 10.1128/mbio.00948-23] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Accepted: 05/08/2023] [Indexed: 09/01/2023] Open
Abstract
IMPORTANCE Biofilms are the communal way of life that microbes adopt to increase survival. Key to our ability to systematically promote or ablate biofilm formation is a detailed understanding of the biofilm matrix macromolecules. Here, we identify the first two essential steps in the Bacillus subtilis biofilm matrix exopolysaccharide (EPS) synthesis pathway. Together, our studies and approaches provide the foundation for the sequential characterization of the steps in EPS biosynthesis, using prior steps to enable chemoenzymatic synthesis of the undecaprenyl diphosphate-linked glycan substrates.
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Affiliation(s)
- Christine A. Arbour
- Department of Biology and Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Rupa Nagar
- Division of Molecular Microbiology, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Hannah M. Bernstein
- Department of Biology and Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Soumi Ghosh
- Department of Biology and Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Yusra Al-Sammarraie
- Division of Molecular Microbiology, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Helge C. Dorfmueller
- Division of Molecular Microbiology, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Michael A. J. Ferguson
- Wellcome Centre for Anti-Infectives Research, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Nicola R. Stanley-Wall
- Division of Molecular Microbiology, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Barbara Imperiali
- Department of Biology and Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
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2
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Arbour CA, Nagar R, Bernstein HM, Ghosh S, Al-Sammarraie Y, Dorfmueller HC, Ferguson MAJ, Stanley-Wall NR, Imperiali B. Defining Early Steps in B. subtilis Biofilm Biosynthesis. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.22.529487. [PMID: 36865097 PMCID: PMC9980142 DOI: 10.1101/2023.02.22.529487] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
Abstract
The Bacillus subtilis extracellular biofilm matrix includes an exopolysaccharide that is critical for the architecture and function of the community. To date, our understanding of the biosynthetic machinery and the molecular composition of the exopolysaccharide of B. subtilis remains unclear and incomplete. This report presents synergistic biochemical and genetic studies built from a foundation of comparative sequence analyses targeted at elucidating the activities of the first two membrane-committed steps in the exopolysaccharide biosynthetic pathway. By taking this approach, we determined the nucleotide sugar donor and lipid-linked acceptor substrates for the first two enzymes in the B. subtilis biofilm exopolysaccharide biosynthetic pathway. EpsL catalyzes the first phosphoglycosyl transferase step using UDP-di- N -acetyl bacillosamine as phospho-sugar donor. EpsD is a GT-B fold glycosyl transferase that facilitates the second step in the pathway that utilizes the product of EpsL as an acceptor substrate and UDP- N -acetyl glucosamine as the sugar donor. Thus, the study defines the first two monosaccharides at the reducing end of the growing exopolysaccharide unit. In doing so we provide the first evidence of the presence of bacillosamine in an exopolysaccharide synthesized by a Gram-positive bacterium. IMPORTANCE Biofilms are the communal way of life that microbes adopt to increase survival. Key to our ability to systematically promote or ablate biofilm formation is a detailed understanding of the biofilm matrix macromolecules. Here we identify the first two essential steps in the Bacillus subtilis biofilm matrix exopolysaccharide synthesis pathway. Together our studies and approaches provide the foundation for the sequential characterization of the steps in exopolysaccharide biosynthesis, using prior steps to enable chemoenzymatic synthesis of the undecaprenol diphosphate-linked glycan substrates.
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Affiliation(s)
- Christine A. Arbour
- Department of Biology and Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139 (USA)
| | - Rupa Nagar
- Division of Molecular Microbiology, School of Life Sciences, University of Dundee, Dundee, DD1 5EH, UK
| | - Hannah M. Bernstein
- Department of Biology and Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139 (USA)
| | - Soumi Ghosh
- Department of Biology and Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139 (USA)
| | - Yusra Al-Sammarraie
- Division of Molecular Microbiology, School of Life Sciences, University of Dundee, Dundee, DD1 5EH, UK
| | - Helge C. Dorfmueller
- Division of Molecular Microbiology, School of Life Sciences, University of Dundee, Dundee, DD1 5EH, UK
| | - Michael A. J. Ferguson
- Wellcome Centre for Anti-Infectives Research, School of Life Sciences, University of Dundee, Dundee, DD1 5EH, UK
| | - Nicola R. Stanley-Wall
- Division of Molecular Microbiology, School of Life Sciences, University of Dundee, Dundee, DD1 5EH, UK
| | - Barbara Imperiali
- Department of Biology and Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139 (USA)
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3
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Lenkeit F, Eckert I, Sinn M, Hauth F, Hartig JS, Weinberg Z. A variant of guanidine-IV riboswitches exhibits evidence of a distinct ligand specificity. RNA Biol 2023; 20:10-19. [PMID: 36548032 PMCID: PMC9788692 DOI: 10.1080/15476286.2022.2160562] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Riboswitches are regulatory RNAs that specifically bind a small molecule or ion. Like metabolite-binding proteins, riboswitches can evolve new ligand specificities, and some examples of this phenomenon have been validated. As part of work based on comparative genomics to discover novel riboswitches, we encountered a candidate riboswitch with striking similarities to the recently identified guanidine-IV riboswitch. This candidate riboswitch, the Gd4v motif, is predicted in four distinct bacterial phyla, thus almost as widespread as the guanidine-IV riboswitch. Bioinformatic and experimental analysis suggest that the Gd4v motif is a riboswitch that binds a ligand other than guanidine. It is found associated with gene classes that differ from genes regulated by confirmed guanidine riboswitches. In inline-probing assays, we showed that free guanidine binds only weakly to one of the tested sequences of the variant. Further tested compounds did not show binding, attenuation of transcription termination, or activation of a genetic reporter construct. We characterized an N-acetyltransferase frequently associated with the Gd4v motif and compared its substrate preference to an N-acetyltransferase that occurs under control of guanidine-IV riboswitches. The substrates of this Gd4v-motif-associated enzyme did not show activity for Gd4v RNA binding or transcription termination. Hence, the ligand of the candidate riboswitch motif remains unidentified. The variant RNA motif is predominantly found in gut metagenome sequences, hinting at a ligand that is highly relevant in this environment. This finding is a first step to determining the identity of this unknown ligand, and understanding how guanidine-IV-riboswitch-like structures can evolve to bind different ligands.
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Affiliation(s)
- Felina Lenkeit
- Department of Chemistry and Konstanz Research School Chemical Biology (KoRS-CB), University of Konstanz, Universitätsstraße 10, 78457Konstanz, Germany
| | - Iris Eckert
- Bioinformatics Group, Department of Computer Science and Interdisciplinary Centre for Bioinformatics, Leipzig University, Härtelstraße 16-18, 04107Leipzig, Germany
| | - Malte Sinn
- Department of Chemistry and Konstanz Research School Chemical Biology (KoRS-CB), University of Konstanz, Universitätsstraße 10, 78457Konstanz, Germany
| | - Franziskus Hauth
- Department of Chemistry and Konstanz Research School Chemical Biology (KoRS-CB), University of Konstanz, Universitätsstraße 10, 78457Konstanz, Germany
| | - Jörg S. Hartig
- Department of Chemistry and Konstanz Research School Chemical Biology (KoRS-CB), University of Konstanz, Universitätsstraße 10, 78457Konstanz, Germany,CONTACT Jörg S. Hartig
| | - Zasha Weinberg
- Bioinformatics Group, Department of Computer Science and Interdisciplinary Centre for Bioinformatics, Leipzig University, Härtelstraße 16-18, 04107Leipzig, Germany,Zasha Weinberg Bioinformatics Group, Department of Computer Science and Interdisciplinary Centre for Bioinformatics, Leipzig University, Härtelstraße 16-18, 04107Leipzig, Germany
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4
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Kikuchi K, Galera-Laporta L, Weatherwax C, Lam JY, Moon EC, Theodorakis EA, Garcia-Ojalvo J, Süel GM. Electrochemical potential enables dormant spores to integrate environmental signals. Science 2022; 378:43-49. [PMID: 36201591 PMCID: PMC10593254 DOI: 10.1126/science.abl7484] [Citation(s) in RCA: 28] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/13/2023]
Abstract
The dormant state of bacterial spores is generally thought to be devoid of biological activity. We show that despite continued dormancy, spores can integrate environmental signals over time through a preexisting electrochemical potential. Specifically, we studied thousands of individual Bacillus subtilis spores that remain dormant when exposed to transient nutrient pulses. Guided by a mathematical model of bacterial electrophysiology, we modulated the decision to exit dormancy by genetically and chemically targeting potassium ion flux. We confirmed that short nutrient pulses result in step-like changes in the electrochemical potential of persistent spores. During dormancy, spores thus gradually release their stored electrochemical potential to integrate extracellular information over time. These findings reveal a decision-making mechanism that operates in physiologically inactive cells.
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Affiliation(s)
- Kaito Kikuchi
- Molecular Biology Section, Division of Biological Sciences, University of California San Diego; La Jolla, CA 92093, USA
| | - Leticia Galera-Laporta
- Molecular Biology Section, Division of Biological Sciences, University of California San Diego; La Jolla, CA 92093, USA
| | - Colleen Weatherwax
- Molecular Biology Section, Division of Biological Sciences, University of California San Diego; La Jolla, CA 92093, USA
| | - Jamie Y Lam
- Department of Chemistry and Biochemistry, University of California San Diego; La Jolla, CA 92093, USA
| | - Eun Chae Moon
- Molecular Biology Section, Division of Biological Sciences, University of California San Diego; La Jolla, CA 92093, USA
| | - Emmanuel A Theodorakis
- Department of Chemistry and Biochemistry, University of California San Diego; La Jolla, CA 92093, USA
| | - Jordi Garcia-Ojalvo
- Department of Medicine and Life Sciences, Universitat Pompeu Fabra; 08003 Barcelona, Spain
- Senior author
| | - Gürol M Süel
- Molecular Biology Section, Division of Biological Sciences, University of California San Diego; La Jolla, CA 92093, USA
- San Diego Center for Systems Biology, University of California San Diego; La Jolla, CA 92093-0380, USA
- Center for Microbiome Innovation, University of California San Diego; La Jolla, CA 92093-0380, USA
- Senior author
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5
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Dey S, Batisse C, Shukla J, Webster MW, Takacs M, Saint-André C, Weixlbaumer A. Structural insights into RNA-mediated transcription regulation in bacteria. Mol Cell 2022; 82:3885-3900.e10. [DOI: 10.1016/j.molcel.2022.09.020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Revised: 07/07/2022] [Accepted: 09/19/2022] [Indexed: 11/06/2022]
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6
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González-Tortuero E, Anthon C, Havgaard JH, Geissler AS, Breüner A, Hjort C, Gorodkin J, Seemann SE. The Bacillaceae-1 RNA motif comprises two distinct classes. Gene 2022; 841:146756. [PMID: 35905857 DOI: 10.1016/j.gene.2022.146756] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2022] [Revised: 06/10/2022] [Accepted: 07/24/2022] [Indexed: 11/04/2022]
Abstract
Non-coding RNAs are key regulatory players in bacteria. Many computationally predicted non-coding RNAs, however, lack functional associations. An example is the Bacillaceae-1 RNA motif, whose Rfam model consists of two hairpin loops. We find the motif conserved in nine of 13 non-pathogenic strains of the genus Bacillus but only in one pathogenic strain. To elucidate functional characteristics, we studied 118 hits of the Rfam model in 11 Bacillus spp. and found two distinct classes based on the ensemble diversity of their RNA secondary structure and the genomic context concerning the ribosomal RNA (rRNA) cluster. Forty hits are associated with the rRNA cluster, of which all 19 hits upstream flanking of 16S rRNA have a reverse complementary structure of low structural diversity. Fifty-two hits have large ensemble diversity, of which 38 are located between two coding genes. For eight hits in Bacillus subtilis, we investigated public expression data under various conditions and observed either the forward or the reverse complementary motif expressed. Five hits are associated with the rRNA cluster. Four of them are located upstream of the 16S rRNA and are not transcriptionally active, but instead, their reverse complements with low structural diversity are expressed together with the rRNA cluster. The three other hits are located between two coding genes in non-conserved genomic loci. Two of them are independently expressed from their surrounding genes and are structurally diverse. In summary, we found that Bacillaceae-1 RNA motifs upstream flanking of ribosomal RNA clusters tend to have one stable structure with the reverse complementary motif expressed in B. subtilis. In contrast, a subgroup of intergenic motifs has the thermodynamic potential for structural switches.
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Affiliation(s)
- Enrique González-Tortuero
- Center for non-coding RNA in Technology and Health (RTH), Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg, Denmark
| | - Christian Anthon
- Center for non-coding RNA in Technology and Health (RTH), Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg, Denmark
| | - Jakob H Havgaard
- Center for non-coding RNA in Technology and Health (RTH), Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg, Denmark
| | - Adrian S Geissler
- Center for non-coding RNA in Technology and Health (RTH), Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg, Denmark
| | | | | | - Jan Gorodkin
- Center for non-coding RNA in Technology and Health (RTH), Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg, Denmark.
| | - Stefan E Seemann
- Center for non-coding RNA in Technology and Health (RTH), Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg, Denmark.
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7
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A Sporulation-Specific sRNA Bvs196 Contributing to the Developing Spore in Bacillus velezensis. Microorganisms 2022; 10:microorganisms10051015. [PMID: 35630459 PMCID: PMC9147052 DOI: 10.3390/microorganisms10051015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2022] [Revised: 05/07/2022] [Accepted: 05/11/2022] [Indexed: 02/01/2023] Open
Abstract
Many putative sRNAs have been characterized using bioinformatic analysis and high-throughput sequencing in Gram-positive Bacillus strains, but there are only a few functional studies on the sRNAs involved in the spore formation developmental process. In particular, there is no sRNA confirmed experimentally to regulate the late stages of sporulation. Bvs196 is an sRNA with a length of 294 nucleotides that is abundantly expressed in the stationary phase of several media and independently transcribed in Bacillus velezensis strain PEBA20, as validated by RNA-seq and Northern blot,. It is also confirmed, by qRT-PCR, that Bvs196 is transcribed abundantly throughout the intermediate and late stages of sporulation. Using the gfpmut3a gene transcriptional reporter demonstrates that Bvs196 is expressed specifically in the forespore during sporulation and controlled by σF and σG (mainly by σG). This was observed by fluorescence microscopy and multi-function microplate reader. Further evolutionary conservation analysis found that Bvs196 is widely present in Bacillus with a strongly conserved and stable secondary structure. Resistance phenotypic assays of spores formed from the Bvs196 deletion mutant, the overexpressed Bvs196 mutant, and the wild-type strain revealed that the absence of Bvs196 led to reduced heat and UV resistance and enhanced formaldehyde resistance. We determined, by MST analysis, that Bvs196 can directly interact with spo0A and sspN-tlp mRNAs in vitro, and that short incomplete complementary paired bases affect the binding affinity of Bvs196 to target mRNAs. Our results suggest that Bvs196 is a novel sporulation-specific sRNA of B. velezensis, 294 nt in length, independently transcribed under the control of σF and σG in the forespore during sporulation, and that it affects spore resistance, and is able to directly interact with spo0A and sspN-tlp mRNAs. The remarkable conservation and impressive expression level of Bvs196 imply that it acts as an important conservative regulator, presumably by interacting with many other unknown targets in the forespore, and therefore contributing to spore properties. This work provides new clues for further understanding of the spore formation regulatory network.
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8
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Miguel-Arribas A, Wu LJ, Michaelis C, Yoshida KI, Grohmann E, Meijer WJJ. Conjugation Operons in Gram-Positive Bacteria with and without Antitermination Systems. Microorganisms 2022; 10:microorganisms10030587. [PMID: 35336162 PMCID: PMC8955417 DOI: 10.3390/microorganisms10030587] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Revised: 03/03/2022] [Accepted: 03/04/2022] [Indexed: 02/01/2023] Open
Abstract
Genes involved in the same cellular process are often clustered together in an operon whose expression is controlled by an upstream promoter. Generally, the activity of the promoter is strictly controlled. However, spurious transcription undermines this strict regulation, particularly affecting large operons. The negative effects of spurious transcription can be mitigated by the presence of multiple terminators inside the operon, in combination with an antitermination system. Antitermination systems modify the transcription elongation complexes and enable them to bypass terminators. Bacterial conjugation is the process by which a conjugative DNA element is transferred from a donor to a recipient cell. Conjugation involves many genes that are mostly organized in one or a few large operons. It has recently been shown that many conjugation operons present on plasmids replicating in Gram-positive bacteria possess a bipartite antitermination system that allows not only many terminators inside the conjugation operon to be bypassed, but also the differential expression of a subset of genes. Here, we show that some conjugation operons on plasmids belonging to the Inc18 family of Gram-positive broad host-range plasmids do not possess an antitermination system, suggesting that the absence of an antitermination system may have advantages. The possible (dis)advantages of conjugation operons possessing (or not) an antitermination system are discussed.
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Affiliation(s)
- Andrés Miguel-Arribas
- Centro de Biología Molecular Severo Ochoa (CSIC-UAM), Instituto de Biología Molecular Eladio Viñuela (CSIC), C. Nicolás Cabrera 1, Universidad Autónoma, Canto Blanco, 28049 Madrid, Spain;
| | - Ling Juan Wu
- Centre for Bacterial Cell Biology, Medical Faculty, Biosciences Institute, Newcastle University, Richardson Road, Newcastle upon Tyne NE2 4AX, UK;
| | - Claudia Michaelis
- School of Life Sciences and Technology, Berlin University of Applied Sciences, Seestrasse 64, 13347 Berlin, Germany;
| | - Ken-ichi Yoshida
- Department of Science, Technology and Innovation, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501, Japan;
| | - Elisabeth Grohmann
- School of Life Sciences and Technology, Berlin University of Applied Sciences, Seestrasse 64, 13347 Berlin, Germany;
- Correspondence: (E.G.); (W.J.J.M.); Tel.: +49-30-4504-3942 (E.G.); +34-91-196-4539 (W.J.J.M.)
| | - Wilfried J. J. Meijer
- Centro de Biología Molecular Severo Ochoa (CSIC-UAM), Instituto de Biología Molecular Eladio Viñuela (CSIC), C. Nicolás Cabrera 1, Universidad Autónoma, Canto Blanco, 28049 Madrid, Spain;
- Correspondence: (E.G.); (W.J.J.M.); Tel.: +49-30-4504-3942 (E.G.); +34-91-196-4539 (W.J.J.M.)
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9
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Abstract
To exert their functions, RNAs adopt diverse structures, ranging from simple secondary to complex tertiary and quaternary folds. In vivo, RNA folding starts with RNA transcription, and a wide variety of processes are coupled to co-transcriptional RNA folding events, including the regulation of fundamental transcription dynamics, gene regulation by mechanisms like attenuation, RNA processing or ribonucleoprotein particle formation. While co-transcriptional RNA folding and associated co-transcriptional processes are by now well accepted as pervasive regulatory principles in all organisms, investigations into the role of the transcription machinery in co-transcriptional folding processes have so far largely focused on effects of the order in which RNA regions are produced and of transcription kinetics. Recent structural and structure-guided functional analyses of bacterial transcription complexes increasingly point to an additional role of RNA polymerase and associated transcription factors in supporting co-transcriptional RNA folding by fostering or preventing strategic contacts to the nascent transcripts. In general, the results support the view that transcription complexes can act as RNA chaperones, a function that has been suggested over 30 years ago. Here, we discuss transcription complexes as RNA chaperones based on recent examples from bacterial transcription.
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Affiliation(s)
- Nelly Said
- Freie Universität Berlin, Department Biology, Chemistry, Pharmacy, Institute of Chemistry and Biochemistry, Laboratory of Structural Biochemistry, Berlin, Germany
| | - Markus C Wahl
- Freie Universität Berlin, Department Biology, Chemistry, Pharmacy, Institute of Chemistry and Biochemistry, Laboratory of Structural Biochemistry, Berlin, Germany.,Helmholtz-Zentrum Berlin Für Materialien Und Energie, Macromolecular Crystallography, Berlin, Germany
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10
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Konikkat S, Scribner MR, Eutsey R, Hiller NL, Cooper VS, McManus J. Quantitative mapping of mRNA 3' ends in Pseudomonas aeruginosa reveals a pervasive role for premature 3' end formation in response to azithromycin. PLoS Genet 2021; 17:e1009634. [PMID: 34252072 PMCID: PMC8297930 DOI: 10.1371/journal.pgen.1009634] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Revised: 07/22/2021] [Accepted: 06/01/2021] [Indexed: 01/06/2023] Open
Abstract
Pseudomonas aeruginosa produces serious chronic infections in hospitalized patients and immunocompromised individuals, including patients with cystic fibrosis. The molecular mechanisms by which P. aeruginosa responds to antibiotics and other stresses to promote persistent infections may provide new avenues for therapeutic intervention. Azithromycin (AZM), an antibiotic frequently used in cystic fibrosis treatment, is thought to improve clinical outcomes through a number of mechanisms including impaired biofilm growth and quorum sensing (QS). The mechanisms underlying the transcriptional response to AZM remain unclear. Here, we interrogated the P. aeruginosa transcriptional response to AZM using a fast, cost-effective genome-wide approach to quantitate RNA 3’ ends (3pMap). We also identified hundreds of P. aeruginosa genes with high incidence of premature 3’ end formation indicative of riboregulation in their transcript leaders using 3pMap. AZM treatment of planktonic and biofilm cultures alters the expression of hundreds of genes, including those involved in QS, biofilm formation, and virulence. Strikingly, most genes downregulated by AZM in biofilms had increased levels of intragenic 3’ ends indicating premature transcription termination, transcriptional pausing, or accumulation of stable intermediates resulting from the action of nucleases. Reciprocally, AZM reduced premature intragenic 3’ end termini in many upregulated genes. Most notably, reduced termination accompanied robust induction of obgE, a GTPase involved in persister formation in P. aeruginosa. Our results support a model in which AZM-induced changes in 3’ end formation alter the expression of central regulators which in turn impairs the expression of QS, biofilm formation and stress response genes, while upregulating genes associated with persistence. Pseudomonas aeruginosa is a common source of hospital-acquired infections and causes prolonged illness in patients with cystic fibrosis. P. aeruginosa infections are often treated with the macrolide antibiotic azithromycin, which changes the expression of many genes involved in infection. By examining such expression changes at nucleotide resolution, we found azithromycin treatment alters the locations of mRNA 3’ ends suggesting most downregulated genes are subject to premature 3’ end formation. We further identified candidate RNA regulatory elements that P. aeruginosa may use to control gene expression. Our work provides new insights in P. aeruginosa gene regulation and its response to antibiotics.
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Affiliation(s)
- Salini Konikkat
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States of America
| | - Michelle R. Scribner
- Department of Microbiology and Molecular Genetics, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Rory Eutsey
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States of America
| | - N. Luisa Hiller
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States of America
| | - Vaughn S. Cooper
- Department of Microbiology and Molecular Genetics, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Joel McManus
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States of America
- * E-mail:
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11
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Bange G, Bedrunka P. Physiology of guanosine-based second messenger signaling in Bacillus subtilis. Biol Chem 2021; 401:1307-1322. [PMID: 32881708 DOI: 10.1515/hsz-2020-0241] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Accepted: 08/22/2020] [Indexed: 12/19/2022]
Abstract
The guanosine-based second messengers (p)ppGpp and c-di-GMP are key players of the physiological regulation of the Gram-positive model organism Bacillus subtilis. Their regulatory spectrum ranges from key metabolic processes over motility to biofilm formation. Here we review our mechanistic knowledge on their synthesis and degradation in response to environmental and stress signals as well as what is known on their cellular effectors and targets. Moreover, we discuss open questions and our gaps in knowledge on these two important second messengers.
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Affiliation(s)
- Gert Bange
- Center for Synthetic Microbiology (SYNMIKRO) and Department of Chemistry, Philipps-University Marburg, Hans-Meerwein-Strasse 6, C07, Marburg, D-35043,Germany
| | - Patricia Bedrunka
- Center for Synthetic Microbiology (SYNMIKRO) and Department of Chemistry, Philipps-University Marburg, Hans-Meerwein-Strasse 6, C07, Marburg, D-35043,Germany
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12
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Elghondakly A, Wu CH, Klupt S, Goodson J, Winkler WC. A NusG Specialized Paralog That Exhibits Specific, High-Affinity RNA-Binding Activity. J Mol Biol 2021; 433:167100. [PMID: 34119489 DOI: 10.1016/j.jmb.2021.167100] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Revised: 05/17/2021] [Accepted: 06/05/2021] [Indexed: 10/21/2022]
Abstract
Bacterial NusG associates with RNA polymerase (RNAP) through its N-terminal domain, while the C-terminal domain (CTD) forms dynamic interactions with Rho, S10, NusB and NusA to affect transcription elongation. While virtually all bacteria encode for a core NusG, many also synthesize paralogs that transiently bind RNAP to alter expression of targeted genes. Yet, despite the importance of the genes they regulate, most of the subfamilies of NusG paralogs (e.g., UpxY, TaA, ActX and LoaP) have not been investigated in depth. Herein, we discover that LoaP requires a small RNA hairpin located within the 5' leader region of its targeted operons. LoaP binds the RNA element with nanomolar affinity and high specificity, in contrast to other NusG proteins, which have not been shown to exhibit RNA-binding activity. These data reveal a sequence feature that can be used to identify LoaP-regulated operons. This discovery also expands the repertoire of macromolecular interactions exhibited by the NusG CTD during transcription elongation to include an RNA ligand.
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Affiliation(s)
- Amr Elghondakly
- The University of Maryland, Department of Chemistry and Biochemistry, College Park, MD, United States
| | - Chih Hao Wu
- The University of Maryland, Department of Cell Biology and Molecular Genetics, College Park, MD, United States
| | - Steven Klupt
- The University of Maryland, Department of Cell Biology and Molecular Genetics, College Park, MD, United States
| | - Jonathan Goodson
- The University of Maryland, Department of Cell Biology and Molecular Genetics, College Park, MD, United States
| | - Wade C Winkler
- The University of Maryland, Department of Chemistry and Biochemistry, College Park, MD, United States; The University of Maryland, Department of Cell Biology and Molecular Genetics, College Park, MD, United States.
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13
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Miguel-Arribas A, Val-Calvo J, Gago-Córdoba C, Izquierdo JM, Abia D, Wu LJ, Errington J, Meijer WJJ. A novel bipartite antitermination system widespread in conjugative elements of Gram-positive bacteria. Nucleic Acids Res 2021; 49:5553-5567. [PMID: 33999173 PMCID: PMC8191782 DOI: 10.1093/nar/gkab360] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Revised: 04/09/2021] [Accepted: 04/23/2021] [Indexed: 11/18/2022] Open
Abstract
Transcriptional regulation allows adaptive and coordinated gene expression, and is essential for life. Processive antitermination systems alter the transcription elongation complex to allow the RNA polymerase to read through multiple terminators in an operon. Here, we describe the discovery of a novel bipartite antitermination system that is widespread among conjugative elements from Gram-positive bacteria, which we named conAn. This system is composed of a large RNA element that exerts antitermination, and a protein that functions as a processivity factor. Besides allowing coordinated expression of very long operons, we show that these systems allow differential expression of genes within an operon, and probably contribute to strict regulation of the conjugation genes by minimizing the effects of spurious transcription. Mechanistic features of the conAn system are likely to decisively influence its host range, with important implications for the spread of antibiotic resistance and virulence genes.
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Affiliation(s)
- Andrés Miguel-Arribas
- Centro de Biología Molecular "Severo Ochoa" (CSIC-UAM), C. Nicolás Cabrera 1, Universidad Autónoma de Madrid, Canto Blanco, 28049 Madrid, Spain
| | - Jorge Val-Calvo
- Centro de Biología Molecular "Severo Ochoa" (CSIC-UAM), C. Nicolás Cabrera 1, Universidad Autónoma de Madrid, Canto Blanco, 28049 Madrid, Spain
| | - César Gago-Córdoba
- Centro de Biología Molecular "Severo Ochoa" (CSIC-UAM), C. Nicolás Cabrera 1, Universidad Autónoma de Madrid, Canto Blanco, 28049 Madrid, Spain
| | - José M Izquierdo
- Centro de Biología Molecular "Severo Ochoa" (CSIC-UAM), C. Nicolás Cabrera 1, Universidad Autónoma de Madrid, Canto Blanco, 28049 Madrid, Spain
| | - David Abia
- Bioinformatics Facility, Centro de Biología Molecular "Severo Ochoa", (CSIC-UAM), C. Nicolás Cabrera 1, Universidad Autónoma de Madrid, Canto Blanco, 28049 Madrid, Spain
| | - Ling Juan Wu
- Centre for Bacterial Cell Biology, Biosciences Institute, Newcastle University, Richardson Road, Newcastle Upon Tyne, NE2 4AX, UK
| | - Jeff Errington
- Centre for Bacterial Cell Biology, Biosciences Institute, Newcastle University, Richardson Road, Newcastle Upon Tyne, NE2 4AX, UK
| | - Wilfried J J Meijer
- Centro de Biología Molecular "Severo Ochoa" (CSIC-UAM), C. Nicolás Cabrera 1, Universidad Autónoma de Madrid, Canto Blanco, 28049 Madrid, Spain
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14
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Sharipova MR, Mardanova AM, Rudakova NL, Pudova DS. Bistability and Formation of the Biofilm Matrix as Adaptive Mechanisms during the Stationary Phase of Bacillus subtilis. Microbiology (Reading) 2021. [DOI: 10.1134/s002626172006017x] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
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15
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Irastortza-Olaziregi M, Amster-Choder O. Coupled Transcription-Translation in Prokaryotes: An Old Couple With New Surprises. Front Microbiol 2021; 11:624830. [PMID: 33552035 PMCID: PMC7858274 DOI: 10.3389/fmicb.2020.624830] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2020] [Accepted: 12/18/2020] [Indexed: 01/17/2023] Open
Abstract
Coupled transcription-translation (CTT) is a hallmark of prokaryotic gene expression. CTT occurs when ribosomes associate with and initiate translation of mRNAs whose transcription has not yet concluded, therefore forming "RNAP.mRNA.ribosome" complexes. CTT is a well-documented phenomenon that is involved in important gene regulation processes, such as attenuation and operon polarity. Despite the progress in our understanding of the cellular signals that coordinate CTT, certain aspects of its molecular architecture remain controversial. Additionally, new information on the spatial segregation between the transcriptional and the translational machineries in certain species, and on the capability of certain mRNAs to localize translation-independently, questions the unanimous occurrence of CTT. Furthermore, studies where transcription and translation were artificially uncoupled showed that transcription elongation can proceed in a translation-independent manner. Here, we review studies supporting the occurrence of CTT and findings questioning its extent, as well as discuss mechanisms that may explain both coupling and uncoupling, e.g., chromosome relocation and the involvement of cis- or trans-acting elements, such as small RNAs and RNA-binding proteins. These mechanisms impact RNA localization, stability, and translation. Understanding the two options by which genes can be expressed and their consequences should shed light on a new layer of control of bacterial transcripts fate.
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Affiliation(s)
- Mikel Irastortza-Olaziregi
- Department of Microbiology and Molecular Genetics, Faculty of Medicine, IMRIC, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Orna Amster-Choder
- Department of Microbiology and Molecular Genetics, Faculty of Medicine, IMRIC, The Hebrew University of Jerusalem, Jerusalem, Israel
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16
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Kim S, Beltran B, Irnov I, Jacobs-Wagner C. Long-Distance Cooperative and Antagonistic RNA Polymerase Dynamics via DNA Supercoiling. Cell 2020; 179:106-119.e16. [PMID: 31539491 DOI: 10.1016/j.cell.2019.08.033] [Citation(s) in RCA: 58] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Revised: 06/14/2019] [Accepted: 08/16/2019] [Indexed: 12/12/2022]
Abstract
Genes are often transcribed by multiple RNA polymerases (RNAPs) at densities that can vary widely across genes and environmental conditions. Here, we provide in vitro and in vivo evidence for a built-in mechanism by which co-transcribing RNAPs display either collaborative or antagonistic dynamics over long distances (>2 kb) through transcription-induced DNA supercoiling. In Escherichia coli, when the promoter is active, co-transcribing RNAPs translocate faster than a single RNAP, but their average speed is not altered by large variations in promoter strength and thus RNAP density. Environmentally induced promoter repression reduces the elongation efficiency of already-loaded RNAPs, causing premature termination and quick synthesis arrest of no-longer-needed proteins. This negative effect appears independent of RNAP convoy formation and is abrogated by topoisomerase I activity. Antagonistic dynamics can also occur between RNAPs from divergently transcribed gene pairs. Our findings may be broadly applicable given that transcription on topologically constrained DNA is the norm across organisms.
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Affiliation(s)
- Sangjin Kim
- Microbial Sciences Institute, Yale University, West Haven, CT 06516, USA; Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06511, USA; Howard Hughes Medical Institute, Yale University, New Haven, CT 06536, USA.
| | - Bruno Beltran
- Microbial Sciences Institute, Yale University, West Haven, CT 06516, USA; Howard Hughes Medical Institute, Yale University, New Haven, CT 06536, USA
| | - Irnov Irnov
- Microbial Sciences Institute, Yale University, West Haven, CT 06516, USA; Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06511, USA; Howard Hughes Medical Institute, Yale University, New Haven, CT 06536, USA
| | - Christine Jacobs-Wagner
- Microbial Sciences Institute, Yale University, West Haven, CT 06516, USA; Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06511, USA; Howard Hughes Medical Institute, Yale University, New Haven, CT 06536, USA; Department of Microbial Pathogenesis, Yale School of Medicine, New Haven, CT 06536, USA.
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17
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Yang CY, Bialecka-Fornal M, Weatherwax C, Larkin JW, Prindle A, Liu J, Garcia-Ojalvo J, Süel GM. Encoding Membrane-Potential-Based Memory within a Microbial Community. Cell Syst 2020; 10:417-423.e3. [PMID: 32343961 PMCID: PMC7286314 DOI: 10.1016/j.cels.2020.04.002] [Citation(s) in RCA: 58] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Revised: 02/13/2020] [Accepted: 04/02/2020] [Indexed: 12/29/2022]
Abstract
Cellular membrane potential plays a key role in the formation and retrieval of memories in the metazoan brain, but it remains unclear whether such memory can also be encoded in simpler organisms like bacteria. Here, we show that single-cell-level memory patterns can be imprinted in bacterial biofilms by light-induced changes in the membrane potential. We demonstrate that transient optical perturbations generate a persistent and robust potassium-channel-mediated change in the membrane potential of bacteria within the biofilm. The light-exposed cells respond in an anti-phase manner, relative to unexposed cells, to both natural and induced oscillations in extracellular ion concentrations. This anti-phase response, which persists for hours following the transient optical stimulus, enables a direct single-cell resolution visualization of spatial memory patterns within the biofilm. The ability to encode robust and persistent membrane-potential-based memory patterns could enable computations within prokaryotic communities and suggests a parallel between neurons and bacteria.
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Affiliation(s)
- Chih-Yu Yang
- Division of Biological Sciences, University of California, San Diego, Pacific Hall Room 2225B, Mail Code 0347, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Maja Bialecka-Fornal
- Division of Biological Sciences, University of California, San Diego, Pacific Hall Room 2225B, Mail Code 0347, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Colleen Weatherwax
- Division of Biological Sciences, University of California, San Diego, Pacific Hall Room 2225B, Mail Code 0347, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Joseph W Larkin
- Division of Biological Sciences, University of California, San Diego, Pacific Hall Room 2225B, Mail Code 0347, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Arthur Prindle
- Division of Biological Sciences, University of California, San Diego, Pacific Hall Room 2225B, Mail Code 0347, 9500 Gilman Drive, La Jolla, CA 92093, USA; Department of Biochemistry and Molecular Genetics, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Jintao Liu
- Division of Biological Sciences, University of California, San Diego, Pacific Hall Room 2225B, Mail Code 0347, 9500 Gilman Drive, La Jolla, CA 92093, USA; Center for Infectious Diseases Research and Tsinghua-Peking Center for Life Sciences, School of Medicine, Tsinghua University, Beijing 100084, People's Republic of China
| | - Jordi Garcia-Ojalvo
- Department of Experimental and Health Sciences, Universitat Pompeu Fabra, Barcelona Biomedical Research Park, Barcelona 08003, Spain
| | - Gürol M Süel
- Division of Biological Sciences, University of California, San Diego, Pacific Hall Room 2225B, Mail Code 0347, 9500 Gilman Drive, La Jolla, CA 92093, USA; San Diego Center for Systems Biology, University of California, San Diego, La Jolla, CA 92093, USA; Center for Microbiome Innovation, University of California, San Diego, La Jolla, CA 92093-0380, USA.
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18
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Richts B, Rosenberg J, Commichau FM. A Survey of Pyridoxal 5'-Phosphate-Dependent Proteins in the Gram-Positive Model Bacterium Bacillus subtilis. Front Mol Biosci 2019; 6:32. [PMID: 31134210 PMCID: PMC6522883 DOI: 10.3389/fmolb.2019.00032] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2019] [Accepted: 04/18/2019] [Indexed: 11/13/2022] Open
Abstract
The B6 vitamer pyridoxal 5′-phosphate (PLP) is a co-factor for proteins and enzymes that are involved in diverse cellular processes. Therefore, PLP is essential for organisms from all kingdoms of life. Here we provide an overview about the PLP-dependent proteins from the Gram-positive soil bacterium Bacillus subtilis. Since B. subtilis serves as a model system in basic research and as a production host in industry, knowledge about the PLP-dependent proteins could facilitate engineering the bacteria for biotechnological applications. The survey revealed that the majority of the PLP-dependent proteins are involved in metabolic pathways like amino acid biosynthesis and degradation, biosynthesis of antibacterial compounds, utilization of nucleotides as well as in iron and carbon metabolism. Many PLP-dependent proteins participate in de novo synthesis of the co-factors biotin, folate, heme, and NAD+ as well as in cell wall metabolism, tRNA modification, regulation of gene expression, sporulation, and biofilm formation. A surprisingly large group of PLP-dependent proteins (29%) belong to the group of poorly characterized proteins. This review underpins the need to characterize the PLP-dependent proteins of unknown function to fully understand the “PLP-ome” of B. subtilis.
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Affiliation(s)
- Björn Richts
- Department of General Microbiology, University of Goettingen, Göttingen, Germany
| | - Jonathan Rosenberg
- Department of General Microbiology, University of Goettingen, Göttingen, Germany
| | - Fabian M Commichau
- Department of General Microbiology, University of Goettingen, Göttingen, Germany
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19
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Abstract
Transcription is a discontinuous process, where each nucleotide incorporation cycle offers a decision between elongation, pausing, halting, or termination. Many cis-acting regulatory RNAs, such as riboswitches, exert their influence over transcription elongation. Through such mechanisms, certain RNA elements can couple physiological or environmental signals to transcription attenuation, a process where cis-acting regulatory RNAs directly influence formation of transcription termination signals. However, through another regulatory mechanism called processive antitermination (PA), RNA polymerase can bypass termination sites over much greater distances than transcription attenuation. PA mechanisms are widespread in bacteria, although only a few classes have been discovered overall. Also, although traditional, signal-responsive riboswitches have not yet been discovered to promote PA, it is increasingly clear that small RNA elements are still oftentimes required. In some instances, small RNA elements serve as loading sites for cellular factors that promote PA. In other instances, larger, more complicated RNA elements participate in PA in unknown ways, perhaps even acting alone to trigger PA activity. These discoveries suggest that what is now needed is a systematic exploration of PA in bacteria, to determine how broadly these transcription elongation mechanisms are utilized, to reveal the diversity in their molecular mechanisms, and to understand the general logic behind their cellular applications. This review covers the known examples of PA regulatory mechanisms and speculates that they may be broadly important to bacteria.
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Affiliation(s)
- Jonathan R. Goodson
- The University of Maryland, Department of Cell Biology and Molecular Genetics, College Park, MD 20742
| | - Wade C. Winkler
- The University of Maryland, Department of Cell Biology and Molecular Genetics, College Park, MD 20742
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20
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Larkin JW, Zhai X, Kikuchi K, Redford SE, Prindle A, Liu J, Greenfield S, Walczak AM, Garcia-Ojalvo J, Mugler A, Süel GM. Signal Percolation within a Bacterial Community. Cell Syst 2018; 7:137-145.e3. [PMID: 30056004 DOI: 10.1016/j.cels.2018.06.005] [Citation(s) in RCA: 58] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Revised: 05/08/2018] [Accepted: 06/07/2018] [Indexed: 12/29/2022]
Abstract
Signal transmission among cells enables long-range coordination in biological systems. However, the scarcity of quantitative measurements hinders the development of theories that relate signal propagation to cellular heterogeneity and spatial organization. We address this problem in a bacterial community that employs electrochemical cell-to-cell communication. We developed a model based on percolation theory, which describes how signals propagate through a heterogeneous medium. Our model predicts that signal transmission becomes possible when the community is organized near a critical phase transition between a disconnected and a fully connected conduit of signaling cells. By measuring population-level signal transmission with single-cell resolution in wild-type and genetically modified communities, we confirm that the spatial distribution of signaling cells is organized at the predicted phase transition. Our findings suggest that at this critical point, the population-level benefit of signal transmission outweighs the single-cell level cost. The bacterial community thus appears to be organized according to a theoretically predicted spatial heterogeneity that promotes efficient signal transmission.
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Affiliation(s)
- Joseph W Larkin
- Division of Biological Sciences, University of California San Diego, Pacific Hall Room 2225B, Mail Code 0347, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Xiaoling Zhai
- Department of Physics and Astronomy, Purdue University, West Lafayette, IN 47907, USA
| | - Kaito Kikuchi
- Division of Biological Sciences, University of California San Diego, Pacific Hall Room 2225B, Mail Code 0347, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Samuel E Redford
- Division of Biological Sciences, University of California San Diego, Pacific Hall Room 2225B, Mail Code 0347, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Arthur Prindle
- Department of Biochemistry and Molecular Genetics, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA; Center for Synthetic Biology, Northwestern University, Evanston, IL 60208, USA
| | - Jintao Liu
- Center for Infectious Diseases Research and Tsinghua-Peking Center for Life Sciences, School of Medicine, Tsinghua University, 100084 Beijing, China
| | - Sacha Greenfield
- Department of Physics and Astronomy, Purdue University, West Lafayette, IN 47907, USA; Department of Physics and Astronomy, Carleton College, Northfield, MN 55057, USA
| | - Aleksandra M Walczak
- Laboratoire de Physique Théorique, CNRS, PSL, Université Pierre et Marie Curie and École Normale Supérieure, Paris 75231, France
| | - Jordi Garcia-Ojalvo
- Department of Experimental and Health Sciences, Universitat Pompeu Fabra, Barcelona 08003, Spain
| | - Andrew Mugler
- Department of Physics and Astronomy, Purdue University, West Lafayette, IN 47907, USA
| | - Gürol M Süel
- Division of Biological Sciences, University of California San Diego, Pacific Hall Room 2225B, Mail Code 0347, 9500 Gilman Drive, La Jolla, CA 92093, USA; San Diego Center for Systems Biology, University of California San Diego, La Jolla, CA 92093, USA.
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21
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Greenlee EB, Stav S, Atilho RM, Brewer KI, Harris KA, Malkowski SN, Mirihana Arachchilage G, Perkins KR, Sherlock ME, Breaker RR. Challenges of ligand identification for the second wave of orphan riboswitch candidates. RNA Biol 2018; 15:377-390. [PMID: 29135333 PMCID: PMC5927730 DOI: 10.1080/15476286.2017.1403002] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2017] [Revised: 10/25/2017] [Accepted: 10/30/2017] [Indexed: 12/18/2022] Open
Abstract
Orphan riboswitch candidates are noncoding RNA motifs whose representatives are believed to function as genetic regulatory elements, but whose target ligands have yet to be identified. The study of certain orphans, particularly classes that have resisted experimental validation for many years, has led to the discovery of important biological pathways and processes once their ligands were identified. Previously, we highlighted details for four of the most common and intriguing orphan riboswitch candidates. This facilitated the validation of riboswitches for the signaling molecules c-di-AMP, ZTP, and ppGpp, the metal ion Mn2+, and the metabolites guanidine and PRPP. Such studies also yield useful linkages between the ligands sensed by the riboswitches and numerous biochemical pathways. In the current report, we describe the known characteristics of 30 distinct classes of orphan riboswitch candidates - some of which have remained unsolved for over a decade. We also discuss the prospects for uncovering novel biological insights via focused studies on these RNAs. Lastly, we make recommendations for experimental objectives along the path to finding ligands for these mysterious RNAs.
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Affiliation(s)
- Etienne B. Greenlee
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT, USA
| | - Shira Stav
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT, USA
| | - Ruben M. Atilho
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, USA
| | - Kenneth I. Brewer
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, USA
| | - Kimberly A. Harris
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT, USA
| | | | | | - Kevin R. Perkins
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT, USA
| | - Madeline E. Sherlock
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, USA
| | - Ronald R. Breaker
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT, USA
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, USA
- Howard Hughes Medical Institute, Yale University, New Haven, CT, USA
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22
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Bidnenko V, Nicolas P, Grylak-Mielnicka A, Delumeau O, Auger S, Aucouturier A, Guerin C, Repoila F, Bardowski J, Aymerich S, Bidnenko E. Termination factor Rho: From the control of pervasive transcription to cell fate determination in Bacillus subtilis. PLoS Genet 2017; 13:e1006909. [PMID: 28723971 PMCID: PMC5540618 DOI: 10.1371/journal.pgen.1006909] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2017] [Revised: 08/02/2017] [Accepted: 07/06/2017] [Indexed: 02/07/2023] Open
Abstract
In eukaryotes, RNA species originating from pervasive transcription are regulators of various cellular processes, from the expression of individual genes to the control of cellular development and oncogenesis. In prokaryotes, the function of pervasive transcription and its output on cell physiology is still unknown. Most bacteria possess termination factor Rho, which represses pervasive, mostly antisense, transcription. Here, we investigate the biological significance of Rho-controlled transcription in the Gram-positive model bacterium Bacillus subtilis. Rho inactivation strongly affected gene expression in B. subtilis, as assessed by transcriptome and proteome analysis of a rho-null mutant during exponential growth in rich medium. Subsequent physiological analyses demonstrated that a considerable part of Rho-controlled transcription is connected to balanced regulation of three mutually exclusive differentiation programs: cell motility, biofilm formation, and sporulation. In the absence of Rho, several up-regulated sense and antisense transcripts affect key structural and regulatory elements of these differentiation programs, thereby suppressing motility and biofilm formation and stimulating sporulation. We dissected how Rho is involved in the activity of the cell fate decision-making network, centered on the master regulator Spo0A. We also revealed a novel regulatory mechanism of Spo0A activation through Rho-dependent intragenic transcription termination of the protein kinase kinB gene. Altogether, our findings indicate that distinct Rho-controlled transcripts are functional and constitute a previously unknown built-in module for the control of cell differentiation in B. subtilis. In a broader context, our results highlight the recruitment of the termination factor Rho, for which the conserved biological role is probably to repress pervasive transcription, in highly integrated, bacterium-specific, regulatory networks.
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Affiliation(s)
- Vladimir Bidnenko
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, France
| | - Pierre Nicolas
- MaIAGE, INRA, Université Paris-Saclay, Jouy-en-Josas, France
| | - Aleksandra Grylak-Mielnicka
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, France
- Institute of Biochemistry and Biophysics PAS, Warsaw, Poland
| | - Olivier Delumeau
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, France
| | - Sandrine Auger
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, France
| | - Anne Aucouturier
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, France
| | - Cyprien Guerin
- MaIAGE, INRA, Université Paris-Saclay, Jouy-en-Josas, France
| | - Francis Repoila
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, France
| | - Jacek Bardowski
- Institute of Biochemistry and Biophysics PAS, Warsaw, Poland
| | - Stéphane Aymerich
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, France
| | - Elena Bidnenko
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, France
- * E-mail:
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23
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Sedlyarova N, Rescheneder P, Magán A, Popitsch N, Rziha N, Bilusic I, Epshtein V, Zimmermann B, Lybecker M, Sedlyarov V, Schroeder R, Nudler E. Natural RNA Polymerase Aptamers Regulate Transcription in E. coli. Mol Cell 2017; 67:30-43.e6. [PMID: 28648779 PMCID: PMC5535762 DOI: 10.1016/j.molcel.2017.05.025] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2017] [Revised: 04/10/2017] [Accepted: 05/23/2017] [Indexed: 01/19/2023]
Abstract
In search for RNA signals that modulate transcription via direct interaction with RNA polymerase (RNAP), we deep sequenced an E. coli genomic library enriched for RNAP-binding RNAs. Many natural RNAP-binding aptamers, termed RAPs, were mapped to the genome. Over 60% of E. coli genes carry RAPs in their mRNA. Combining in vitro and in vivo approaches, we characterized a subset of inhibitory RAPs (iRAPs) that promote Rho-dependent transcription termination. A representative iRAP within the coding region of the essential gene, nadD, greatly reduces its transcriptional output in stationary phase and under oxidative stress, demonstrating that iRAPs control gene expression in response to changing environment. The mechanism of iRAPs involves active uncoupling of transcription and translation, making nascent RNA accessible to Rho. iRAPs encoded in the antisense strand also promote gene expression by reducing transcriptional interference. In essence, our work uncovers a broad class of cis-acting RNA signals that globally control bacterial transcription.
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Affiliation(s)
- Nadezda Sedlyarova
- Department of Biochemistry and Cell Biology, Max F. Perutz Laboratories, University of Vienna, Dr. Bohrgasse 9/5, 1030 Vienna, Austria
| | - Philipp Rescheneder
- Center for Integrative Bioinformatics Vienna, Max F. Perutz Laboratories, University of Vienna & Medical University of Vienna, 1030 Vienna, Austria
| | - Andrés Magán
- Department of Biochemistry and Cell Biology, Max F. Perutz Laboratories, University of Vienna, Dr. Bohrgasse 9/5, 1030 Vienna, Austria
| | - Niko Popitsch
- Children's Cancer Research Institute, St. Anna Kinderkrebsforschung, 1090 Vienna, Austria
| | - Natascha Rziha
- Department of Biochemistry and Cell Biology, Max F. Perutz Laboratories, University of Vienna, Dr. Bohrgasse 9/5, 1030 Vienna, Austria
| | - Ivana Bilusic
- Department of Biochemistry and Cell Biology, Max F. Perutz Laboratories, University of Vienna, Dr. Bohrgasse 9/5, 1030 Vienna, Austria
| | - Vitaly Epshtein
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY 10016, USA
| | - Bob Zimmermann
- Department of Molecular Evolution and Development, University of Vienna, Althanstrasse 14, 1090 Vienna, Austria
| | - Meghan Lybecker
- University of Colorado, 1420 Austin Bluffs Parkway, Colorado Springs, CO 80918, USA
| | - Vitaly Sedlyarov
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, 1090 Vienna, Austria
| | - Renée Schroeder
- Department of Biochemistry and Cell Biology, Max F. Perutz Laboratories, University of Vienna, Dr. Bohrgasse 9/5, 1030 Vienna, Austria.
| | - Evgeny Nudler
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY 10016, USA; Howard Hughes Medical Institute, New York University School of Medicine, New York, NY 10016, USA.
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24
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Goodson JR, Klupt S, Zhang C, Straight P, Winkler WC. LoaP is a broadly conserved antiterminator protein that regulates antibiotic gene clusters in Bacillus amyloliquefaciens. Nat Microbiol 2017; 2:17003. [PMID: 28191883 DOI: 10.1038/nmicrobiol.2017.3] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Accepted: 01/04/2017] [Indexed: 01/22/2023]
Abstract
A valuable resource available in the search for new natural products is the diverse microbial life that spans the planet. A large subset of these microorganisms synthesize complex specialized metabolites exhibiting biomedically important activities. A limiting step to the characterization of these compounds is an elucidation of the genetic regulatory mechanisms that oversee their production. Although proteins that control transcription initiation of specialized metabolite gene clusters have been identified, those affecting transcription elongation have not been broadly investigated. In this study, we analysed the phylogenetic distribution of the large, widespread NusG family of transcription elongation proteins and found that it includes a cohesive outgroup of paralogues (herein coined LoaP), which are often positioned adjacent or within gene clusters for specialized metabolites. We established Bacillus amyloliquefaciens LoaP as a paradigm for this protein subgroup and showed that it regulated the transcriptional readthrough of termination sites located within two different antibiotic biosynthesis operons. Both of these antibiotics have been implicated in plant-protective activities, demonstrating that LoaP controls an important regulon of specialized metabolite genes for this microorganism. These data therefore reveal transcription elongation as a point of regulatory control for specialized metabolite pathways and introduce a subgroup of NusG proteins for this purpose.
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Affiliation(s)
- Jonathan R Goodson
- Department of Cell Biology and Molecular Genetics, The University of Maryland, 3112 Biosciences Research Building, College Park, Maryland 20742, USA
| | - Steven Klupt
- Department of Cell Biology and Molecular Genetics, The University of Maryland, 3112 Biosciences Research Building, College Park, Maryland 20742, USA
| | - Chengxi Zhang
- Department of Biochemistry and Biophysics, Texas A&M University, TAMU 2128 - Rm 435, College Station, Texas 77843, USA
| | - Paul Straight
- Department of Biochemistry and Biophysics, Texas A&M University, TAMU 2128 - Rm 435, College Station, Texas 77843, USA
| | - Wade C Winkler
- Department of Cell Biology and Molecular Genetics, The University of Maryland, 3112 Biosciences Research Building, College Park, Maryland 20742, USA
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25
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Humphries J, Xiong L, Liu J, Prindle A, Yuan F, Arjes HA, Tsimring L, Süel GM. Species-Independent Attraction to Biofilms through Electrical Signaling. Cell 2017; 168:200-209.e12. [PMID: 28086091 DOI: 10.1016/j.cell.2016.12.014] [Citation(s) in RCA: 172] [Impact Index Per Article: 24.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Revised: 10/17/2016] [Accepted: 12/09/2016] [Indexed: 12/30/2022]
Abstract
Bacteria residing within biofilm communities can coordinate their behavior through cell-to-cell signaling. However, it remains unclear if these signals can also influence the behavior of distant cells that are not part of the community. Using a microfluidic approach, we find that potassium ion channel-mediated electrical signaling generated by a Bacillus subtilis biofilm can attract distant cells. Integration of experiments and mathematical modeling indicates that extracellular potassium emitted from the biofilm alters the membrane potential of distant cells, thereby directing their motility. This electrically mediated attraction appears to be a generic mechanism that enables cross-species interactions, as Pseudomonas aeruginosa cells also become attracted to the electrical signal released by the B. subtilis biofilm. Cells within a biofilm community can thus not only coordinate their own behavior but also influence the behavior of diverse bacteria at a distance through long-range electrical signaling. PAPERCLIP.
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Affiliation(s)
- Jacqueline Humphries
- Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA
| | - Liyang Xiong
- Department of Physics, University of California, San Diego, La Jolla, CA 92093, USA
| | - Jintao Liu
- Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA
| | - Arthur Prindle
- Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA
| | - Fang Yuan
- Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA
| | - Heidi A Arjes
- Department of Bioengineering, Stanford University, Stanford, CA 94305, USA; Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA 94305-5101, USA
| | - Lev Tsimring
- BioCircuits Institute, University of California, San Diego, La Jolla, CA 92093, USA; San Diego Center for Systems Biology, University of California, San Diego, La Jolla, CA 92093, USA
| | - Gürol M Süel
- Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA; BioCircuits Institute, University of California, San Diego, La Jolla, CA 92093, USA; San Diego Center for Systems Biology, University of California, San Diego, La Jolla, CA 92093, USA; Center for Microbiome Innovation, Jacobs School of Engineering, University of California, San Diego, La Jolla, CA 92093, USA.
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26
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Regulatory RNAs in Bacillus subtilis: a Gram-Positive Perspective on Bacterial RNA-Mediated Regulation of Gene Expression. Microbiol Mol Biol Rev 2016; 80:1029-1057. [PMID: 27784798 DOI: 10.1128/mmbr.00026-16] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Bacteria can employ widely diverse RNA molecules to regulate their gene expression. Such molecules include trans-acting small regulatory RNAs, antisense RNAs, and a variety of transcriptional attenuation mechanisms in the 5' untranslated region. Thus far, most regulatory RNA research has focused on Gram-negative bacteria, such as Escherichia coli and Salmonella. Hence, there is uncertainty about whether the resulting insights can be extrapolated directly to other bacteria, such as the Gram-positive soil bacterium Bacillus subtilis. A recent study identified 1,583 putative regulatory RNAs in B. subtilis, whose expression was assessed across 104 conditions. Here, we review the current understanding of RNA-based regulation in B. subtilis, and we categorize the newly identified putative regulatory RNAs on the basis of their conservation in other bacilli and the stability of their predicted secondary structures. Our present evaluation of the publicly available data indicates that RNA-mediated gene regulation in B. subtilis mostly involves elements at the 5' ends of mRNA molecules. These can include 5' secondary structure elements and metabolite-, tRNA-, or protein-binding sites. Importantly, sense-independent segments are identified as the most conserved and structured potential regulatory RNAs in B. subtilis. Altogether, the present survey provides many leads for the identification of new regulatory RNA functions in B. subtilis.
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27
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Kriner MA, Groisman EA. RNA secondary structures regulate three steps of Rho-dependent transcription termination within a bacterial mRNA leader. Nucleic Acids Res 2016; 45:631-642. [PMID: 28123036 PMCID: PMC5314796 DOI: 10.1093/nar/gkw889] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2016] [Revised: 09/20/2016] [Accepted: 09/30/2016] [Indexed: 11/14/2022] Open
Abstract
Transcription termination events in bacteria often require the RNA helicase Rho. Typically, Rho promotes termination at the end of coding sequences, but it can also terminate transcription within leader regions to implement regulatory decisions. Rho-dependent termination requires initial recognition of a Rho utilization (rut) site on a nascent RNA by Rho's primary binding surface. However, it is presently unclear what factors determine the location of transcription termination, how RNA secondary structures influence this process and whether mechanistic differences distinguish constitutive from regulated Rho-dependent terminators. We previously demonstrated that the 5′ leader mRNA of the Salmonella corA gene can adopt two mutually exclusive conformations that dictate accessibility of a rut site to Rho. We now report that the corA leader also controls two subsequent steps of Rho-dependent termination. First, the RNA conformation that presents an accessible rut site promotes pausing of RNA polymerase (RNAP) at a single Rho-dependent termination site over 100 nt downstream. Second, an additional RNA stem-loop promotes Rho activity and controls the location at which Rho-dependent termination occurs, despite having no effect on initial Rho binding to the corA leader. Thus, the multi-step nature of Rho-dependent termination may facilitate regulation of a given coding region by multiple cytoplasmic signals.
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Affiliation(s)
- Michelle A Kriner
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT 06536, USA.,Microbial Sciences Institute, Yale University, West Haven, CT 06516, USA
| | - Eduardo A Groisman
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT 06536, USA .,Microbial Sciences Institute, Yale University, West Haven, CT 06516, USA
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Majed R, Faille C, Kallassy M, Gohar M. Bacillus cereus Biofilms-Same, Only Different. Front Microbiol 2016; 7:1054. [PMID: 27458448 PMCID: PMC4935679 DOI: 10.3389/fmicb.2016.01054] [Citation(s) in RCA: 119] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2016] [Accepted: 06/23/2016] [Indexed: 12/24/2022] Open
Abstract
Bacillus cereus displays a high diversity of lifestyles and ecological niches and include beneficial as well as pathogenic strains. These strains are widespread in the environment, are found on inert as well as on living surfaces and contaminate persistently the production lines of the food industry. Biofilms are suspected to play a key role in this ubiquitous distribution and in this persistency. Indeed, B. cereus produces a variety of biofilms which differ in their architecture and mechanism of formation, possibly reflecting an adaptation to various environments. Depending on the strain, B. cereus has the ability to grow as immersed or floating biofilms, and to secrete within the biofilm a vast array of metabolites, surfactants, bacteriocins, enzymes, and toxins, all compounds susceptible to act on the biofilm itself and/or on its environment. Within the biofilm, B. cereus exists in different physiological states and is able to generate highly resistant and adhesive spores, which themselves will increase the resistance of the bacterium to antimicrobials or to cleaning procedures. Current researches show that, despite similarities with the regulation processes and effector molecules involved in the initiation and maturation of the extensively studied Bacillus subtilis biofilm, important differences exists between the two species. The present review summarizes the up to date knowledge on biofilms produced by B. cereus and by two closely related pathogens, Bacillus thuringiensis and Bacillus anthracis. Economic issues caused by B. cereus biofilms and management strategies implemented to control these biofilms are included in this review, which also discuss the ecological and functional roles of biofilms in the lifecycle of these bacterial species and explore future developments in this important research area.
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Affiliation(s)
- Racha Majed
- Micalis Institute, INRA, AgroParisTech, CNRS, Université Paris-SaclayJouy-en-Josas, France; Unité de Recherche Technologies et Valorisation Alimentaire, Laboratoire de Biotechnologie, Université Saint-JosephBeirut, Lebanon
| | - Christine Faille
- UMR UMET: Unité Matériaux et Transformations, Centre National de la Recherche Scientifique, Institut National de la Recherche Agronomique, Université de Lille Villeneuve d'Ascq, France
| | - Mireille Kallassy
- Unité de Recherche Technologies et Valorisation Alimentaire, Laboratoire de Biotechnologie, Université Saint-Joseph Beirut, Lebanon
| | - Michel Gohar
- Micalis Institute, INRA, AgroParisTech, CNRS, Université Paris-SaclayJouy-en-Josas, France; Unité de Recherche Technologies et Valorisation Alimentaire, Laboratoire de Biotechnologie, Université Saint-JosephBeirut, Lebanon
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29
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Dar D, Shamir M, Mellin JR, Koutero M, Stern-Ginossar N, Cossart P, Sorek R. Term-seq reveals abundant ribo-regulation of antibiotics resistance in bacteria. Science 2016; 352:aad9822. [PMID: 27120414 DOI: 10.1126/science.aad9822] [Citation(s) in RCA: 227] [Impact Index Per Article: 28.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2015] [Accepted: 02/24/2016] [Indexed: 12/12/2022]
Abstract
Riboswitches and attenuators are cis-regulatory RNA elements, most of which control bacterial gene expression via metabolite-mediated, premature transcription termination. We developed an unbiased experimental approach for genome-wide discovery of such ribo-regulators in bacteria. We also devised an experimental platform that quantitatively measures the in vivo activity of all such regulators in parallel and enables rapid screening for ribo-regulators that respond to metabolites of choice. Using this approach, we detected numerous antibiotic-responsive ribo-regulators that control antibiotic resistance genes in pathogens and in the human microbiome. Studying one such regulator in Listeria monocytogenes revealed an attenuation mechanism mediated by antibiotic-stalled ribosomes. Our results expose broad roles for conditional termination in regulating antibiotic resistance and provide a tool for discovering riboswitches and attenuators that respond to previously unknown ligands.
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Affiliation(s)
- Daniel Dar
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Maya Shamir
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - J R Mellin
- Institut Pasteur, Unité des Interactions Bactéries-Cellules, Paris, F-75015 France. INSERM, U604, Paris, F-75015 France. Institut National de la Recherche Agronomique, USC2020, Paris, F-75015 France
| | - Mikael Koutero
- Institut Pasteur, Unité des Interactions Bactéries-Cellules, Paris, F-75015 France. INSERM, U604, Paris, F-75015 France. Institut National de la Recherche Agronomique, USC2020, Paris, F-75015 France
| | - Noam Stern-Ginossar
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Pascale Cossart
- Institut Pasteur, Unité des Interactions Bactéries-Cellules, Paris, F-75015 France. INSERM, U604, Paris, F-75015 France. Institut National de la Recherche Agronomique, USC2020, Paris, F-75015 France
| | - Rotem Sorek
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel.
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30
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Zhang J, Landick R. A Two-Way Street: Regulatory Interplay between RNA Polymerase and Nascent RNA Structure. Trends Biochem Sci 2016; 41:293-310. [PMID: 26822487 DOI: 10.1016/j.tibs.2015.12.009] [Citation(s) in RCA: 99] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2015] [Revised: 12/21/2015] [Accepted: 12/22/2015] [Indexed: 02/06/2023]
Abstract
The vectorial (5'-to-3' at varying velocity) synthesis of RNA by cellular RNA polymerases (RNAPs) creates a rugged kinetic landscape, demarcated by frequent, sometimes long-lived, pauses. In addition to myriad gene-regulatory roles, these pauses temporally and spatially program the co-transcriptional, hierarchical folding of biologically active RNAs. Conversely, these RNA structures, which form inside or near the RNA exit channel, interact with the polymerase and adjacent protein factors to influence RNA synthesis by modulating pausing, termination, antitermination, and slippage. Here, we review the evolutionary origin, mechanistic underpinnings, and regulatory consequences of this interplay between RNAP and nascent RNA structure. We categorize and rationalize the extensive linkage between the transcriptional machinery and its product, and provide a framework for future studies.
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Affiliation(s)
- Jinwei Zhang
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD 20892, USA.
| | - Robert Landick
- Departments of Biochemistry and Bacteriology, University of Wisconsin-Madison, Madison, WI 53706, USA.
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31
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Ion channels enable electrical communication in bacterial communities. Nature 2015; 527:59-63. [PMID: 26503040 DOI: 10.1038/nature15709] [Citation(s) in RCA: 427] [Impact Index Per Article: 47.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Accepted: 09/10/2015] [Indexed: 12/15/2022]
Abstract
The study of bacterial ion channels has provided fundamental insights into the structural basis of neuronal signalling; however, the native role of ion channels in bacteria has remained elusive. Here we show that ion channels conduct long-range electrical signals within bacterial biofilm communities through spatially propagating waves of potassium. These waves result from a positive feedback loop, in which a metabolic trigger induces release of intracellular potassium, which in turn depolarizes neighbouring cells. Propagating through the biofilm, this wave of depolarization coordinates metabolic states among cells in the interior and periphery of the biofilm. Deletion of the potassium channel abolishes this response. As predicted by a mathematical model, we further show that spatial propagation can be hindered by specific genetic perturbations to potassium channel gating. Together, these results demonstrate a function for ion channels in bacterial biofilms, and provide a prokaryotic paradigm for active, long-range electrical signalling in cellular communities.
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32
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Abstract
Cells that reside within a community can cooperate and also compete with each other for resources. It remains unclear how these opposing interactions are resolved at the population level. Here we investigate such an internal conflict within a microbial (Bacillus subtilis) biofilm community: cells in the biofilm periphery not only protect interior cells from external attack but also starve them through nutrient consumption. We discover that this conflict between protection and starvation is resolved through emergence of long-range metabolic co-dependence between peripheral and interior cells. As a result, biofilm growth halts periodically, increasing nutrient availability for the sheltered interior cells. We show that this collective oscillation in biofilm growth benefits the community in the event of a chemical attack. These findings indicate that oscillations support population-level conflict resolution by coordinating competing metabolic demands in space and time, suggesting new strategies to control biofilm growth.
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33
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Zhang F, Kwan A, Xu A, Süel GM. A Synthetic Quorum Sensing System Reveals a Potential Private Benefit for Public Good Production in a Biofilm. PLoS One 2015. [PMID: 26196509 PMCID: PMC4510612 DOI: 10.1371/journal.pone.0132948] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Bacteria predominantly reside in microbial communities known as biofilms, where cells are encapsulated and protected by the extracellular matrix (ECM). While all biofilm cells benefit from the ECM, only a subgroup of cells carries the burden of producing this public good. This dilemma provokes the question of how these cells balance the cost of ECM production. Here we show that ECM producing cells have a higher gene expression response to quorum sensing (QS) signals, which can lead to a private benefit. Specifically, we constructed a synthetic quorum-sensing system with designated “Sender” and “Receiver” cells in Bacillus subtilis. This synthetic QS system allowed us to uncouple and independently investigate ECM production and QS in both biofilms and single cells. Results revealed that ECM production directly enhances the response to QS signals, which may offset the cost of ECM production.
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Affiliation(s)
- Fang Zhang
- Division of Biological Sciences, Section of Molecular Biology, University of California San Diego, San Diego, California, United States of America
- University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Anna Kwan
- Division of Biological Sciences, Section of Molecular Biology, University of California San Diego, San Diego, California, United States of America
| | - Amy Xu
- Division of Biological Sciences, Section of Molecular Biology, University of California San Diego, San Diego, California, United States of America
| | - Gürol M. Süel
- Division of Biological Sciences, Section of Molecular Biology, University of California San Diego, San Diego, California, United States of America
- * E-mail:
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34
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Cooper CA, Mainprize IL, Nickerson NN. Genetic, Biochemical, and Structural Analyses of Bacterial Surface Polysaccharides. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2015; 883:295-315. [PMID: 26621474 DOI: 10.1007/978-3-319-23603-2_16] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Surface polysaccharides are an often essential component of the outer surface of bacteria. They may serve to protect organisms from harsh environmental conditions and to increase virulence. The focus of this review will be to introduce polysaccharide biosynthesis and export from the cell, and the associated techniques used to determine these glycostructures. Protein interactions and proteomics will then be discussed while introducing systems biology approaches used to determine protein-protein and protein-polysaccharide interactions. The final section will address related screening methods used to study gene regulation in bacteria relating to polysaccharide gene clusters and their associated regulators. The goal of this review will be to highlight key studies that have increased our knowledge of glycobiology and discuss novel methods that examine this field at the cellular level using systems biology.
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Affiliation(s)
- Colin A Cooper
- Agriculture and Food Laboratory, Laboratory Services, University of Guelph, 95 Stone Rd. W., Guelph, ON, N1H 8J7, Canada.
| | - Iain L Mainprize
- Department of Molecular and Cellular Biology, University of Guelph, 95 Stone Road, Guelph, ON, N1H 8J7, Canada
| | - Nicholas N Nickerson
- Department of Molecular and Cellular Biology, University of Guelph, 95 Stone Road, Guelph, ON, N1H 8J7, Canada.,Department of Infectious Diseases, Genentech Inc., South San Francisco, CA, 94080, USA
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35
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36
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Abstract
Bacterial flagellar motility is among the most extensively studied physiological systems in biology, but most research has been restricted to using the highly similar Gram-negative species Escherichia coli and Salmonella enterica. Here, we review the recent advances in the study of flagellar structure and regulation of the distantly related and genetically tractable Gram-positive bacterium Bacillus subtilis. B. subtilis has a thicker layer of peptidoglycan and lacks the outer membrane of the Gram-negative bacteria; thus, not only phylogenetic separation but also differences in fundamental cell architecture contribute to deviations in flagellar structure and regulation. We speculate that a large number of flagella and the absence of a periplasm make B. subtilis a premier organism for the study of the earliest events in flagellar morphogenesis and the type III secretion system. Furthermore, B. subtilis has been instrumental in the study of heterogeneous gene transcription in subpopulations and of flagellar regulation at the translational and functional level.
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37
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Fu Y, Deiorio-Haggar K, Soo MW, Meyer MM. Bacterial RNA motif in the 5' UTR of rpsF interacts with an S6:S18 complex. RNA (NEW YORK, N.Y.) 2014; 20:168-76. [PMID: 24310371 PMCID: PMC3895269 DOI: 10.1261/rna.041285.113] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Approximately half the transcripts encoding ribosomal proteins in Escherichia coli include a structured RNA motif that interacts with a specific ribosomal protein to inhibit gene expression, thus allowing stoichiometric production of ribosome components. However, many of these RNA structures are not widely distributed across bacterial phyla. It is increasingly common for RNA motifs associated with ribosomal protein genes to be identified using comparative genomic methods, yet these are rarely experimentally validated. In this work, we characterize one such motif that precedes operons containing rpsF and rpsR, which encode ribosomal proteins S6 and S18. This RNA structure is widely distributed across many phyla of bacteria despite differences within the downstream operon, and examples are present in both E. coli and Bacillus subtilis. We demonstrate a direct interaction between an example of the RNA from B. subtilis and an S6:S18 complex using in vitro binding assays, verify our predicted secondary structure, and identify a putative protein-binding site. The proposed binding site bears a strong resemblance to the S18 binding site within the 16S rRNA, suggesting molecular mimicry. This interaction is a valuable addition to the canon of ribosomal protein mRNA interactions. This work shows how experimental verification translates computational results into concrete knowledge of biological systems.
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38
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Fagerlund A, Dubois T, Økstad OA, Verplaetse E, Gilois N, Bennaceur I, Perchat S, Gominet M, Aymerich S, Kolstø AB, Lereclus D, Gohar M. SinR controls enterotoxin expression in Bacillus thuringiensis biofilms. PLoS One 2014; 9:e87532. [PMID: 24498128 PMCID: PMC3909190 DOI: 10.1371/journal.pone.0087532] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2013] [Accepted: 12/29/2013] [Indexed: 11/21/2022] Open
Abstract
The entomopathogen Bacillus thuringiensis produces dense biofilms under various conditions. Here, we report that the transition phase regulators Spo0A, AbrB and SinR control biofilm formation and swimming motility in B. thuringiensis, just as they control biofilm formation and swarming motility in the closely related saprophyte species B. subtilis. However, microarray analysis indicated that in B. thuringiensis, in contrast to B. subtilis, SinR does not control an eps operon involved in exopolysaccharides production, but regulates genes involved in the biosynthesis of the lipopeptide kurstakin. This lipopeptide is required for biofilm formation and was previously shown to be important for survival in the host cadaver (necrotrophism). Microarray analysis also revealed that the SinR regulon contains genes coding for the Hbl enterotoxin. Transcriptional fusion assays, Western blots and hemolysis assays confirmed that SinR controls Hbl expression, together with PlcR, the main virulence regulator in B. thuringiensis. We show that Hbl is expressed in a sustained way in a small subpopulation of the biofilm, whereas almost all the planktonic population transiently expresses Hbl. The gene coding for SinI, an antagonist of SinR, is expressed in the same biofilm subpopulation as hbl, suggesting that hbl transcription heterogeneity is SinI-dependent. B. thuringiensis and B. cereus are enteric bacteria which possibly form biofilms lining the host intestinal epithelium. Toxins produced in biofilms could therefore be delivered directly to the target tissue.
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Affiliation(s)
- Annette Fagerlund
- Laboratory for Microbial Dynamics (LaMDa) and Department of Pharmaceutical Biosciences, School of Pharmacy, University of Oslo, Oslo, Norway
| | - Thomas Dubois
- Micalis, INRA (UMR1319), Domaine de Vilvert, Jouy-en-Josas, France
- Micalis, AgroParistech (UMR1319), Domaine de Vilvert, Jouy-en-Josas, France
| | - Ole-Andreas Økstad
- Laboratory for Microbial Dynamics (LaMDa) and Department of Pharmaceutical Biosciences, School of Pharmacy, University of Oslo, Oslo, Norway
| | - Emilie Verplaetse
- Micalis, INRA (UMR1319), Domaine de Vilvert, Jouy-en-Josas, France
- Micalis, AgroParistech (UMR1319), Domaine de Vilvert, Jouy-en-Josas, France
| | - Nathalie Gilois
- Micalis, INRA (UMR1319), Domaine de Vilvert, Jouy-en-Josas, France
- Micalis, AgroParistech (UMR1319), Domaine de Vilvert, Jouy-en-Josas, France
| | - Imène Bennaceur
- Micalis, INRA (UMR1319), Domaine de Vilvert, Jouy-en-Josas, France
- Micalis, AgroParistech (UMR1319), Domaine de Vilvert, Jouy-en-Josas, France
| | - Stéphane Perchat
- Micalis, INRA (UMR1319), Domaine de Vilvert, Jouy-en-Josas, France
- Micalis, AgroParistech (UMR1319), Domaine de Vilvert, Jouy-en-Josas, France
| | - Myriam Gominet
- Institut Pasteur, CNRS URA 2172, Unité de Biologie des Bactéries Pathogènes à Gram positif, Paris, France
| | - Stéphane Aymerich
- Micalis, INRA (UMR1319), Domaine de Vilvert, Jouy-en-Josas, France
- Micalis, AgroParistech (UMR1319), Domaine de Vilvert, Jouy-en-Josas, France
| | - Anne-Brit Kolstø
- Laboratory for Microbial Dynamics (LaMDa) and Department of Pharmaceutical Biosciences, School of Pharmacy, University of Oslo, Oslo, Norway
| | - Didier Lereclus
- Micalis, INRA (UMR1319), Domaine de Vilvert, Jouy-en-Josas, France
- Micalis, AgroParistech (UMR1319), Domaine de Vilvert, Jouy-en-Josas, France
| | - Michel Gohar
- Micalis, INRA (UMR1319), Domaine de Vilvert, Jouy-en-Josas, France
- Micalis, AgroParistech (UMR1319), Domaine de Vilvert, Jouy-en-Josas, France
- * E-mail:
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39
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Guttenplan SB, Kearns DB. Regulation of flagellar motility during biofilm formation. FEMS Microbiol Rev 2013; 37:849-71. [PMID: 23480406 DOI: 10.1111/1574-6976.12018] [Citation(s) in RCA: 378] [Impact Index Per Article: 34.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2012] [Revised: 01/07/2013] [Accepted: 02/07/2013] [Indexed: 11/30/2022] Open
Abstract
Many bacteria swim in liquid or swarm over solid surfaces by synthesizing rotary flagella. The same bacteria that are motile also commonly form nonmotile multicellular aggregates called biofilms. Biofilms are an important part of the lifestyle of pathogenic bacteria, and it is assumed that there is a motility-to-biofilm transition wherein the inhibition of motility promotes biofilm formation. The transition is largely inferred from regulatory mutants that reveal the opposite regulation of the two phenotypes. Here, we review the regulation of motility during biofilm formation in Bacillus, Pseudomonas, Vibrio, and Escherichia, and we conclude that the motility-to-biofilm transition, if necessary, likely involves two steps. In the short term, flagella are functionally regulated to either inhibit rotation or modulate the basal flagellar reversal frequency. Over the long term, flagellar gene transcription is inhibited and in the absence of de novo synthesis, flagella are diluted to extinction through growth. Both short-term and long-term motility inhibition is likely important to stabilize cell aggregates and optimize resource investment. We emphasize the newly discovered flagellar functional regulators and speculate that others await discovery in the context of biofilm formation.
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Abstract
We have discovered that 6S-1 RNA (encoded by bsrA) is important for appropriate timing of sporulation in Bacillus subtilis in that cells lacking 6S-1 RNA sporulate earlier than wild-type cells. The time to generate a mature spore once the decision to sporulate has been made is unaffected by 6S-1 RNA, and, therefore, we propose that it is the timing of onset of sporulation that is altered. Interestingly, the presence of cells lacking 6S-1 RNA in coculture leads to all cell types exhibiting an early-sporulation phenotype. We propose that cells lacking 6S-1 RNA modify their environment in a manner that promotes early sporulation. In support of this model, resuspension of wild-type cells in conditioned medium from ΔbsrA cultures also resulted in early sporulation. Use of Escherichia coli growth as a reporter of the nutritional status of conditioned media suggested that B. subtilis cells lacking 6S-1 RNA reduce the nutrient content of their environment earlier than wild-type cells. Several pathways known to impact the timing of sporulation, such as the skf- and sdp-dependent cannibalism pathways, were eliminated as potential targets of 6S-1 RNA-mediated changes, suggesting that 6S-1 RNA activity defines a novel mechanism for altering the timing of onset of sporulation. In addition, 6S-2 RNA does not influence the timing of sporulation, providing further evidence of the independent influences of these two related RNAs on cell physiology.
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Vlamakis H, Chai Y, Beauregard P, Losick R, Kolter R. Sticking together: building a biofilm the Bacillus subtilis way. Nat Rev Microbiol 2013; 11:157-68. [PMID: 23353768 DOI: 10.1038/nrmicro2960] [Citation(s) in RCA: 599] [Impact Index Per Article: 54.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Biofilms are ubiquitous communities of tightly associated bacteria encased in an extracellular matrix. Bacillus subtilis has long served as a robust model organism to examine the molecular mechanisms of biofilm formation, and a number of studies have revealed that this process is regulated by several integrated pathways. In this Review, we focus on the molecular mechanisms that control B. subtilis biofilm assembly, and then briefly summarize the current state of knowledge regarding biofilm disassembly. We also discuss recent progress that has expanded our understanding of B. subtilis biofilm formation on plant roots, which are a natural habitat for this soil bacterium.
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Affiliation(s)
- Hera Vlamakis
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, Massachusetts 02115, USA
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Abstract
Antiterminator RNA directly modifies the transcription elongation complex so that it terminates less efficiently at intrinsic and factor-dependent terminators. These unusual RNAs were first discovered in bacteriophage HK022, where the nascent transcripts of the phage put sites promote full expression of phage genes during lytic infection. The activity of antiterminator RNA depends on specific structural elements that form as the transcript exits RNA polymerase. To further our understanding of the critical sequence features that permit RNA to serve as a transcriptional antiterminator, we have identified eight antiterminator RNA sequences in bacteriophages or prophages. There is strong sequence conservation among most of the put sequences, but sequence divergence is tolerated if critical structural elements are preserved. The most diverged antiterminator RNA is found in bacteriophage HK639. The HK639 putL transcript is an efficient antiterminator, and it has a novel structural feature that is critical for its activity. HK639 also displays a unique pattern of sensitivity to amino acid substitutions in the β' subunit zinc binding domain of RNA polymerase, adding to existing evidence that this domain interacts specifically with antiterminator RNA.
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Karunakaran E, Mukherjee J, Ramalingam B, Biggs CA. "Biofilmology": a multidisciplinary review of the study of microbial biofilms. Appl Microbiol Biotechnol 2011; 90:1869-81. [PMID: 21538113 DOI: 10.1007/s00253-011-3293-4] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2010] [Revised: 03/26/2011] [Accepted: 03/27/2011] [Indexed: 11/29/2022]
Abstract
The observation of biofilm formation is not a new phenomenon. The prevalence and significance of biofilm and aggregate formation in various processes have encouraged extensive research in this field for more than 40 years. In this review, we highlight techniques from different disciplines that have been used to successfully describe the extracellular, surface and intracellular elements that are predominant in understanding biofilm formation. To reduce the complexities involved in studying biofilms, researchers in the past have generally taken a parts-based, disciplinary specific approach to understand the different components of biofilms in isolation from one another. Recently, a few studies have looked into combining the different techniques to achieve a more holistic understanding of biofilms, yet this approach is still in its infancy. In order to attain a global understanding of the processes involved in the formation of biofilms and to formulate effective biofilm control strategies, researchers in the next decade should recognise that the study of biofilms, i.e. biofilmology, has evolved into a discipline in its own right and that mutual cooperation between the various disciplines towards a multidisciplinary research vision is vital in this field.
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Affiliation(s)
- Esther Karunakaran
- Department of Chemical and Biological Engineering, ChELSI Institute, The University of Sheffield, Sheffield, UK
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Bastet L, Dubé A, Massé E, Lafontaine DA. New insights into riboswitch regulation mechanisms. Mol Microbiol 2011; 80:1148-54. [PMID: 21477128 DOI: 10.1111/j.1365-2958.2011.07654.x] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Riboswitches are genetic elements located in non-coding regions of some messenger RNAs (mRNAs) that are present in all three domains of life. The binding of ligands to riboswitches induces conformational changes in the mRNA molecule, resulting in modulation of gene transcription, or RNA splicing, translation or stability. This mechanism of regulation is particularly widespread in bacteria and allows a direct response to various metabolic changes. A large number of riboswitches have been discovered in the last few years, suggesting the existence of a huge diversity of regulatory ligands and genetic mechanisms of regulation. This review focuses on recent discoveries in riboswitch regulatory mechanisms as well as current outstanding challenges.
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Affiliation(s)
- Laurène Bastet
- Département de biologie, Faculté des sciences, Groupe ARN/RNA Group, Université de Sherbrooke, Sherbrooke, Québec, Canada
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Santangelo TJ, Artsimovitch I. Termination and antitermination: RNA polymerase runs a stop sign. Nat Rev Microbiol 2011; 9:319-29. [PMID: 21478900 DOI: 10.1038/nrmicro2560] [Citation(s) in RCA: 141] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Termination signals induce rapid and irreversible dissociation of the nascent transcript from RNA polymerase. Terminators at the end of genes prevent unintended transcription into the downstream genes, whereas terminators in the upstream regulatory leader regions adjust expression of the structural genes in response to metabolic and environmental signals. Premature termination within an operon leads to potentially deleterious defects in the expression of the downstream genes, but also provides an important surveillance mechanism. This Review discusses the actions of bacterial and phage antiterminators that allow RNA polymerase to override a terminator when the circumstances demand it.
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Affiliation(s)
- Thomas J Santangelo
- Department of Microbiology and The RNA Group, The Ohio State University, Columbus, Ohio 43210, USA
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Martini L, Mansy SS. Cell-like systems with riboswitch controlled gene expression. Chem Commun (Camb) 2011; 47:10734-6. [DOI: 10.1039/c1cc13930d] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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Zhang J, Lau MW, Ferré-D'Amaré AR. Ribozymes and riboswitches: modulation of RNA function by small molecules. Biochemistry 2010; 49:9123-31. [PMID: 20931966 DOI: 10.1021/bi1012645] [Citation(s) in RCA: 127] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Diverse small molecules interact with catalytic RNAs (ribozymes) as substrates and cofactors, and their intracellular concentrations are sensed by gene-regulatory mRNA domains (riboswitches) that modulate transcription, splicing, translation, or RNA stability. Although recognition mechanisms vary from RNA to RNA, structural analyses reveal recurring strategies that arise from the intrinsic properties of RNA such as base pairing and stacking with conjugated heterocycles, and cation-dependent recognition of anionic functional groups. These studies also suggest that, to a first approximation, the magnitude of ligand-induced reorganization of an RNA is inversely proportional to the complexity of the riboswitch or ribozyme. How these small molecule binding-induced changes in RNA lead to alteration in gene expression is less well understood. While different riboswitches have been proposed to be under either kinetic or thermodynamic control, the biochemical and structural mechanisms that give rise to regulatory consequences downstream of small molecule recognition by RNAs mostly remain to be elucidated.
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Affiliation(s)
- Jinwei Zhang
- Howard Hughes Medical Institute, Seattle, Washington 98109-1024, USA
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Burrell M, Hanfrey CC, Murray EJ, Stanley-Wall NR, Michael AJ. Evolution and multiplicity of arginine decarboxylases in polyamine biosynthesis and essential role in Bacillus subtilis biofilm formation. J Biol Chem 2010; 285:39224-38. [PMID: 20876533 DOI: 10.1074/jbc.m110.163154] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Arginine decarboxylases (ADCs; EC 4.1.1.19) from four different protein fold families are important for polyamine biosynthesis in bacteria, archaea, and plants. Biosynthetic alanine racemase fold (AR-fold) ADC is widespread in bacteria and plants. We report the discovery and characterization of an ancestral form of the AR-fold ADC in the bacterial Chloroflexi and Bacteroidetes phyla. The ancestral AR-fold ADC lacks a large insertion found in Escherichia coli and plant AR-fold ADC and is more similar to the lysine biosynthetic enzyme meso-diaminopimelate decarboxylase, from which it has evolved. An E. coli acid-inducible ADC belonging to the aspartate aminotransferase fold (AAT-fold) is involved in acid resistance but not polyamine biosynthesis. We report here that the acid-inducible AAT-fold ADC has evolved from a shorter, ancestral biosynthetic AAT-fold ADC by fusion of a response regulator receiver domain protein to the N terminus. Ancestral biosynthetic AAT-fold ADC appears to be limited to firmicute bacteria. The phylogenetic distribution of different forms of ADC distinguishes bacteria from archaea, euryarchaeota from crenarchaeota, double-membraned from single-membraned bacteria, and firmicutes from actinobacteria. Our findings extend to eight the different enzyme forms carrying out the activity described by EC 4.1.1.19. ADC gene clustering reveals that polyamine biosynthesis employs diverse and exchangeable synthetic modules. We show that in Bacillus subtilis, ADC and polyamines are essential for biofilm formation, and this appears to be an ancient, evolutionarily conserved function of polyamines in bacteria. Also of relevance to human health, we found that arginine decarboxylation is the dominant pathway for polyamine biosynthesis in human gut microbiota.
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Affiliation(s)
- Matthew Burrell
- Institute of Food Research, Norwich Research Park, Colney, Norwich NR4 7UA, United Kingdom
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