The Role of RNA Secondary Structure in Regulation of Gene Expression in Bacteria
Total Page:16
File Type:pdf, Size:1020Kb
Load more
Recommended publications
-
Chapter 18 Regulation of Gene Expression Regulation of Gene Expression • Important for Cellular Control and Differentiation
Chapter 18 Regulation of Gene Expression Regulation of Gene Expression • Important for cellular control and differentiation. • Understanding “expression” is a “hot” area in Biology. General Mechanisms 1. Regulate Gene Expression 2. Regulate Protein Activity Operon Model • Jacob and Monod (1961) - Prokaryotic model of gene control. • Always on the National AP Biology exam! Operon Structure 1. Regulatory Gene 2. Operon Area a. Promoter b. Operator c. Structural Genes Gene Structures Regulatory Gene • Makes Repressor Protein which may bind to the operator. • Repressor protein blocks transcription. Promoter • Attachment sequence on the DNA for RNA polymerase to start transcription. Operator • The "Switch”, binding site for Repressor Protein. • If blocked, will not permit RNA polymerase to pass, preventing transcription. Structural Genes • Make the enzymes for the metabolic pathway. Lac Operon • For digesting Lactose. • Inducible Operon - only works (on) when the substrate (lactose) is present. If no Lactose • Repressor binds to operator. • Operon is "off”, no transcription, no enzymes made If Lactose is absent If Lactose is present • Repressor binds to Lactose instead of operator. • Operon is "on”, transcription occurs, enzymes are made. If Lactose is present Enzymes • Digest Lactose. • When enough Lactose is digested, the Repressor can bind to the operator and switch the Operon "off”. Net Result • The cell only makes the Lactose digestive enzymes when the substrate is present, saving time and energy. Animation • http://www.biostudio.com/d_%20Lac%20Ope ron.htm trp Operon • Makes/synthesizes Tryptophan. • Repressible Operon. – Predict how it is different from the inducible operon… If no Tryptophan • Repressor protein is inactive, Operon "on” Tryptophan made. • “Normal” state for the cell. -
Bacterial RNA Polymerase Can Retain Σ Throughout Transcription
Bacterial RNA polymerase can retain σ70 throughout transcription Timothy T. Hardena,b, Christopher D. Wellsc, Larry J. Friedmanb, Robert Landickd,e, Ann Hochschildc, Jane Kondeva,1, and Jeff Gellesb,1 aDepartment of Physics, Brandeis University, Waltham, MA 02454; bDepartment of Biochemistry, Brandeis University, Waltham, MA 02454; cDepartment of Microbiology and Immunobiology, Harvard Medical School, Boston, MA 02115; dDepartment of Biochemistry, University of Wisconsin, Madison, WI 53706; and eDepartment of Bacteriology, University of Wisconsin, Madison, WI 53706 Edited by Jeffrey W. Roberts, Cornell University, Ithaca, NY, and approved December 10, 2015 (received for review July 15, 2015) Production of a messenger RNA proceeds through sequential stages early elongation pause. This early elongation pause, in turn, al- of transcription initiation and transcript elongation and termination. lows loading of an antitermination factor that enables tran- During each of these stages, RNA polymerase (RNAP) function is scription of the late gene operon (10, 13–15). Similar promoter- regulated by RNAP-associated protein factors. In bacteria, RNAP- proximal pause elements are also associated with many E. coli associated σ factors are strictly required for promoter recognition promoters (16–19), but the function of these elements is yet and have historically been regarded as dedicated initiation factors. unknown. Furthermore, σ70 interaction sites on core RNAP par- However, the primary σ factor in Escherichia coli, σ70,canremain tially overlap with those of transcription elongation factors such as associated with RNAP during the transition from initiation to elon- NusA, NusG, and RfaH (20–23). This and other evidence raises the gation, influencing events that occur after initiation. Quantitative possibility that σ70 retained in TECs sterically occludes the binding studies on the extent of σ70 retention have been limited to com- of other factors, which in turn could affect processes modulated by plexes halted during early elongation. -
High-Resolution RNA 3 -Ends Mapping of Bacterial Rho-Dependent
Nucleic Acids Research, 2018 1 doi: 10.1093/nar/gky274 High-resolution RNA 3-ends mapping of bacterial Rho-dependent transcripts Daniel Dar and Rotem Sorek* Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel Received February 21, 2018; Revised March 29, 2018; Editorial Decision March 31, 2018; Accepted April 04, 2018 ABSTRACT defined according to their dependence on the proteinaceous termination factor, Rho (4). Transcription termination in bacteria can occur ei- Rho-independent terminators, also known as intrinsic ther via Rho-dependent or independent (intrinsic) terminators, efficiently destabilize the elongating RNA- mechanisms. Intrinsic terminators are composed of polymerase (RNAP) complex in the absence of Rho and a stem-loop RNA structure followed by a uridine are encoded by a short ∼30nt DNA sequence downstream stretch and are known to terminate in a precise man- of the protein-coding region of the gene, as well as in some ner. In contrast, Rho-dependent terminators have regulatory 5 mRNA leaders (5,6). These terminators are more loosely defined characteristics and are thought composed of two main modules: a GC-rich sequence that to terminate in a diffuse manner. While transcripts folds into an energetically stable stem-loop RNA structure ending in an intrinsic terminator are protected from and a 7–8 nt uridine rich sequence (7–10). Termination ini- 3-5 exonuclease digestion due to the stem-loop tiates when the U-rich tract is transcribed and occupies the transcription bubble, causing the RNAP to pause and al- structure of the terminator, it remains unclear what lowing the upstream stem-loop forming sequence to nucle- protects Rho-dependent transcripts from being de- ate, which disrupts the transcription complex (8,9,11). -
Recent Developments in Terminator Technology in Saccharomyces Cerevisiae
Journal of Bioscience and Bioengineering VOL. 128 No. 6, 655e661, 2019 www.elsevier.com/locate/jbiosc REVIEW Recent developments in terminator technology in Saccharomyces cerevisiae Takashi Matsuyama1 Toyota Central R&D Lab, Nagakute, Aichi 480-1192, Japan Received 20 March 2019; accepted 7 June 2019 Available online 16 July 2019 Metabolically engineered microorganisms that produce useful organic compounds will be helpful for realizing a sustainable society. The budding yeast Saccharomyces cerevisiae has high utility as a metabolic engineering platform because of its high fermentation ability, non-pathogenicity, and ease of handling. When producing yeast strains that produce exogenous compounds, it is a prerequisite to control the expression of exogenous enzyme-encoding genes. Terminator region in a gene expression cassette, as well as promoter region, could be used to improve metabolically engineered yeasts by increasing or decreasing the expression of the target enzyme-encoding genes. The findings on terminators have grown rapidly in the last decade, so an overview of these findings should provide a foothold for new developments. Ó 2019, The Society for Biotechnology, Japan. All rights reserved. [Key words: Terminator; Metabolic engineering; Genetic switch; Gene expression; Synthetic biology; Saccharomyces cerevisiae] In order to realize a sustainable society, many studies have been metabolic engineering, (iv) terminator selection for optimization of conducted to develop microorganisms that efficiently produce gene expression, (v) use of terminators as genetic switches, (vi) useful organic compounds using metabolic engineering (1). mechanism of action of highly active terminators and (vii) chal- Saccharomyces cerevisiae is considered to have high utility as a lenges in artificial terminator development. platform for these genetically-modified microorganisms for rea- sons such as high fermentation ability, high safety and easy BASIC FUNCTIONS OF THE TERMINATOR handling (2). -
RNA-Based Regulation of Genes of Tryptophan Synthesis and Degradation, in Bacteria
REVIEW RNA-based regulation of genes of tryptophan synthesis and degradation, in bacteria CHARLES YANOFSKY Department of Biological Sciences, Stanford University Stanford, California 94305, USA ABSTRACT We are now aware that RNA-based regulatory mechanisms are commonly used to control gene expression in many organisms. These mechanisms offer the opportunity to exploit relatively short, unique RNA sequences, in altering transcription, translation, and/or mRNA stability, in response to the presence of a small or large signal molecule. The ability of an RNA segment to fold and form alternative hairpin secondary structures—each dedicated to a different regulatory function—permits selection of specific sequences that can affect transcription and/or translation. In the present paper I will focus on our current understanding of the RNA-based regulatory mechanisms used by Escherichia coli and Bacillus subtilis in controlling expression of the tryptophan biosynthetic operon. The regulatory mechanisms they use for this purpose differ, suggesting that these organisms, or their ancestors, adopted different strategies during their evolution. I will also describe the RNA-based mechanism used by E. coli in regulating expression of its operon responsible for tryptophan degradation, the tryptophanase operon. Keywords: trp operon; trp suboperon; aro supraoperon; tna operon; transcription attenuation; T box regulation; tryptophan as a regulatory signal; tRNATrp as a regulatory signal; peptidyl-tRNA; ribosome mediated regulation INTRODUCTION A second regulatory lesson learned over the years is that information within mRNAs, or other RNAs, as well as small Studies over the past 50+ years have revealed that metabolites and other molecules—in addition to DNA and optimization of gene expression has been a major evolu- proteins—often provides specific regulatory signals, or tionary objective for most species. -
RNA Polymerase Clamp Movement Aids Dissociation from DNA but Is Not Required for RNA Release at Intrinsic Terminators
bioRxiv preprint doi: https://doi.org/10.1101/453969; this version posted October 26, 2018. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-NC-ND 4.0 International license. RNA polymerase clamp movement aids dissociation from DNA but is not required for RNA release at intrinsic terminators Michael J Bellecourta, Ananya Ray-Sonia,1, Alex Harwiga, Rachel Anne Mooneya, Robert Landicka,b* Departments of aBiochemistry and bBacteriology, University of Wisconsin–Madison, Madison, WI 53706, USA 1Present address: Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, 02114, USA *To whom correspondence should be addressed; Tel: +1 (608) 265-8475; Fax: +1 (608) 890- 2415; E-mail: [email protected] Highlights • The contributions of RNAP conformation changes during termination are ill-defined • Restricting RNAP clamp movement affects elongation rate, but not termination rate • RNA but not DNA can release at terminators when clamp movement is restricted • Inhibiting TL conformational flexibility impairs both RNA and DNA release Keywords: Escherichia coli, Termination commitment, Transcription elongation, Transcription pausing, Trigger loop Abbreviations: EC, elongating transcription complex; fxlink, crosslinking efficiency; Cys-pair, cysteine-pair; MccJ25, microcin J25; NA, nucleic acid; RNAP, RNA polymerase; TE, termination (commitment) efficiency; Thp, terminator hairpin; TL, trigger loop Declarations of interest: none Bellecourt et al. Page 1 10/25/2018 bioRxiv preprint doi: https://doi.org/10.1101/453969; this version posted October 26, 2018. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. -
Chapter 3. the Beginnings of Genomic Biology – Molecular
Chapter 3. The Beginnings of Genomic Biology – Molecular Genetics Contents 3. The beginnings of Genomic Biology – molecular genetics 3.1. DNA is the Genetic Material 3.6.5. Translation initiation, elongation, and termnation 3.2. Watson & Crick – The structure of DNA 3.6.6. Protein Sorting in Eukaryotes 3.3. Chromosome structure 3.7. Regulation of Eukaryotic Gene Expression 3.3.1. Prokaryotic chromosome structure 3.7.1. Transcriptional Control 3.3.2. Eukaryotic chromosome structure 3.7.2. Pre-mRNA Processing Control 3.3.3. Heterochromatin & Euchromatin 3.4. DNA Replication 3.7.3. mRNA Transport from the Nucleus 3.4.1. DNA replication is semiconservative 3.7.4. Translational Control 3.4.2. DNA polymerases 3.7.5. Protein Processing Control 3.4.3. Initiation of replication 3.7.6. Degradation of mRNA Control 3.4.4. DNA replication is semidiscontinuous 3.7.7. Protein Degradation Control 3.4.5. DNA replication in Eukaryotes. 3.8. Signaling and Signal Transduction 3.4.6. Replicating ends of chromosomes 3.8.1. Types of Cellular Signals 3.5. Transcription 3.8.2. Signal Recognition – Sensing the Environment 3.5.1. Cellular RNAs are transcribed from DNA 3.8.3. Signal transduction – Responding to the Environment 3.5.2. RNA polymerases catalyze transcription 3.5.3. Transcription in Prokaryotes 3.5.4. Transcription in Prokaryotes - Polycistronic mRNAs are produced from operons 3.5.5. Beyond Operons – Modification of expression in Prokaryotes 3.5.6. Transcriptions in Eukaryotes 3.5.7. Processing primary transcripts into mature mRNA 3.6. Translation 3.6.1. -
Bicyclomycin Sensitivity and Resistance Affect Rho Factor-Mediated Transcription Termination in the Tna Operon of Escherichia Coli
JOURNAL OF BACTERIOLOGY, Aug. 1995, p. 4451–4456 Vol. 177, No. 15 0021-9193/95/$04.0010 Copyright 1995, American Society for Microbiology Bicyclomycin Sensitivity and Resistance Affect Rho Factor-Mediated Transcription Termination in the tna Operon of Escherichia coli CHARLES YANOFSKY* AND VIRGINIA HORN Department of Biological Sciences, Stanford University, Stanford, California 94305-5020 Received 13 March 1995/Accepted 27 May 1995 The growth-inhibiting drug bicyclomycin, known to be an inhibitor of Rho factor activity in Escherichia coli, was shown to increase basal level expression of the tryptophanase (tna) operon and to allow growth of a tryptophan auxotroph on indole. The drug also relieved polarity in the trp operon and permitted growth of a trp double nonsense mutant on indole. Nine bicyclomycin-resistant mutants were isolated and partially characterized. Recombination data and genetic and biochemical complementation analyses suggest that five have mutations that affect rho, three have mutations that affect rpoB, and one has a mutation that affects a third locus, near rpoB. Individual mutants showed decreased, normal, or increased basal-level expression of the tna operon. All but one of the resistant mutants displayed greatly increased tna operon expression when grown in the presence of bicyclomycin. The tna operon of the wild-type drug-sensitive parent was also shown to be highly expressed during growth with noninhibitory concentrations of bicyclomycin. These findings demonstrate that resistance to this drug may be acquired by mutations at any one of three loci, two of which appear to be rho and rpoB. Zwiefka et al. (24) found that the antibiotic bicyclomycin segment and interacts with the transcribing RNA polymerase (bicozamycin), an inhibitor of the growth of several gram- molecule, causing it to terminate transcription (7, 9). -
Structural and Mechanistic Studies of the THI Box and SMK Box Riboswitches
Structural and Mechanistic Studies of the THI Box and SMK Box Riboswitches Dissertation Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of The Ohio State University By Angela Mae Smith, M.S. Graduate Program in Microbiology The Ohio State University 2009 Dissertation Committee: Professor Tina Henkin, Advisor Professor Kurt Fredrick Professor Michael Ibba Professor Ross Dalbey ABSTRACT Organisms have evolved a variety of mechanisms for regulating gene expression. Expression of individual genes is carefully modulated during different stages of cell development and in response to changing environmental conditions. A number of regulatory mechanisms involve structural elements within messenger RNAs (mRNAs) that, in response to an environmental signal, undergo a conformational change that affects expression of a gene encoded on that mRNA. RNA elements of this type that operate independently of proteins or translating ribosomes are termed riboswitches. In this work, the THI box and SMK box riboswitches were investigated in order to gain insight into the structural basis for ligand recognition and the mechanism of regulation employed by each of these RNAs. Both riboswitches are predicted to regulate at the level of translation initiation using a mechanism in which the Shine-Dalgarno (SD) sequence is occluded in response to ligand binding. For the THI box riboswitch, the studies presented here demonstrated that 30S ribosomal subunit binding at the SD region decreases in the presence of thiamin pyrophosphate (TPP). Mutation of conserved residues in the ligand binding domain resulted in loss of TPP-dependent repression in vivo. Based on these experiments two classes of mutant phenotypes were identified. -
The RNA Hairpin (Escherichia Coli/RNA Polymerase/Rho-Independent Termination) KEVIN S
Proc. Natl. Acad. Sci. USA Vol. 92, pp. 8793-8797, September 1995 Biochemistry Transcription termination at intrinsic terminators: The role of the RNA hairpin (Escherichia coli/RNA polymerase/rho-independent termination) KEVIN S. WILSONt AND PETER H. VON HIPPEL Institute of Molecular Biology and Department of Chemistry, University of Oregon, Eugene, OR 97403 Contributed by Peter H. von Hippel, April 28, 1995 ABSTRACT Intrinsic termination of transcription in protein-dependent antitermination (Rees et al., unpublished Escherichia coli involves the formation of an RNA hairpin in data) and is likely to be quite general. In this view transcript the nascent RNA. This hairpin plays a central role in the termination is considered to be possible, in principle, at every release of the transcript and polymerase at intrinsic termi- template position. In practice, however, termination does not nation sites on the DNA template. We have created variants of occur at most template positions because the stability of the the AtR2 terminator hairpin and examined the relationship elongation complex results in characteristic half-times for between the structure and stability of this hairpin and the complex dissociation and RNA release of hours or days, while template positions and efficiencies of termination. The results the average dwell-time for elongation at a given template were used to test the simple nucleic acid destabilization model position at saturating NTP concentrations is 10-50 msec (3). of Yager and von Hippel and showed that this model must be It has been shown for the AtR2 terminator (2) and confirmed modified to provide a distinct role for the rU-rich sequence in for the AtR' terminator (Rees et al., unpublished data) that the the nascent RNA, since a perfect palindromic sequence that is termination pathway becomes accessible at intrinsic termina- sufficiently long to form an RNA hairpin that could destabilize tors because the transcription complex is massively destabi- the entire putative 12-bp RNADNA hybrid does not trigger lized in the vicinity of these sites. -
Subcellular Localization in Bacteria: from Envz/Ompr to Transertion
University of Pennsylvania ScholarlyCommons Publicly Accessible Penn Dissertations Summer 2011 Subcellular Localization in Bacteria: From EnvZ/OmpR to Transertion Elizabeth Libby University of Pennsylvania, [email protected] Follow this and additional works at: https://repository.upenn.edu/edissertations Part of the Biological and Chemical Physics Commons, and the Microbiology Commons Recommended Citation Libby, Elizabeth, "Subcellular Localization in Bacteria: From EnvZ/OmpR to Transertion" (2011). Publicly Accessible Penn Dissertations. 974. https://repository.upenn.edu/edissertations/974 This paper is posted at ScholarlyCommons. https://repository.upenn.edu/edissertations/974 For more information, please contact [email protected]. Subcellular Localization in Bacteria: From EnvZ/OmpR to Transertion Abstract The internal structures of the bacterial cell and the associated dynamic changes as a function of physiological state have only recently begun to be characterized. Here we explore two aspects of subcellular localization in E. coli cells: the cytoplasmic distribution of the response regulator OmpR and its regulated chromosomal genes, and the subcellular repositioning of chromosomal loci encoding membrane proteins upon induction. To address these questions by quantitative fluorescence microscopy, we developed a simple system to tag virtually any chromosomal location with arrays of lacO or tetO by extending and modifying existing tools. An unexplained subcellular localization was reported for a functional fluorescent protein fusion to the response regulator OmpR in Escherichia coli. The pronounced regions of increased fluorescence, or foci, are dependent on OmpR phosphorylation, and do not occupy fixed, easily identifiable positions, such as the poles or midcell. Here we show that the foci are due to OmpR-YFP binding specific sites in the chromosome. -
I = Chpt 15. Positive and Negative Transcriptional Control at Lac BMB
BMB 400 Part Four - I = Chpt 15. Positive and Negative Transcriptional Control at lac B M B 400 Part Four: Gene Regulation Section I = Chapter 15 POSITIVE AND NEGATIVE CONTROL SHOWN BY THE lac OPERON OF E. COLI A. Definitions and general comments 1. Operons An operon is a cluster of coordinately regulated genes. It includes structural genes (generally encoding enzymes), regulatory genes (encoding, e.g. activators or repressors) and regulatory sites (such as promoters and operators). 2. Negative versus positive control a. The type of control is defined by the response of the operon when no regulatory protein is present. b. In the case of negative control, the genes in the operon are expressed unless they are switched off by a repressor protein. Thus the operon will be turned on constitutively (the genes will be expressed) when the repressor in inactivated. c. In the case of positive control, the genes are expressed only when an active regulator protein, e.g. an activator, is present. Thus the operon will be turned off when the positive regulatory protein is absent or inactivated. Table 4.1.1. Positive vs. negative control BMB 400 Part Four - I = Chpt 15. Positive and Negative Transcriptional Control at lac 3. Catabolic versus biosynthetic operons a. Catabolic pathways catalyze the breakdown of nutrients (the substrate for the pathway) to generate energy, or more precisely ATP, the energy currency of the cell. In the absence of the substrate, there is no reason for the catabolic enzymes to be present, and the operon encoding them is repressed. In the presence of the substrate, when the enzymes are needed, the operon is induced or de-repressed.