1
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Kannaiah S, Goldberger O, Alam N, Barnabas G, Pozniak Y, Nussbaum-Shochat A, Schueler-Furman O, Geiger T, Amster-Choder O. MinD-RNase E interplay controls localization of polar mRNAs in E. coli. EMBO J 2024; 43:637-662. [PMID: 38243117 PMCID: PMC10897333 DOI: 10.1038/s44318-023-00026-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Revised: 12/11/2023] [Accepted: 12/18/2023] [Indexed: 01/21/2024] Open
Abstract
The E. coli transcriptome at the cell's poles (polar transcriptome) is unique compared to the membrane and cytosol. Several factors have been suggested to mediate mRNA localization to the membrane, but the mechanism underlying polar localization of mRNAs remains unknown. Here, we combined a candidate system approach with proteomics to identify factors that mediate mRNAs localization to the cell poles. We identified the pole-to-pole oscillating protein MinD as an essential factor regulating polar mRNA localization, although it is not able to bind RNA directly. We demonstrate that RNase E, previously shown to interact with MinD, is required for proper localization of polar mRNAs. Using in silico modeling followed by experimental validation, the membrane-binding site in RNase E was found to mediate binding to MinD. Intriguingly, not only does MinD affect RNase E interaction with the membrane, but it also affects its mode of action and dynamics. Polar accumulation of RNase E in ΔminCDE cells resulted in destabilization and depletion of mRNAs from poles. Finally, we show that mislocalization of polar mRNAs may prevent polar localization of their protein products. Taken together, our findings show that the interplay between MinD and RNase E determines the composition of the polar transcriptome, thus assigning previously unknown roles for both proteins.
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Affiliation(s)
- Shanmugapriya Kannaiah
- Department of Microbiology and Molecular Genetics, IMRIC, The Hebrew University Faculty of Medicine, P.O.Box 12272, 91120, Jerusalem, Israel.
- Department of Molecular Microbiology, Washington University School of Medicine, St Louis, MO, 63110, USA.
| | - Omer Goldberger
- Department of Microbiology and Molecular Genetics, IMRIC, The Hebrew University Faculty of Medicine, P.O.Box 12272, 91120, Jerusalem, Israel
| | - Nawsad Alam
- Department of Microbiology and Molecular Genetics, IMRIC, The Hebrew University Faculty of Medicine, P.O.Box 12272, 91120, Jerusalem, Israel
- Department of Biochemistry, University of Oxford, Oxford, OX1 3QU, UK
| | - Georgina Barnabas
- Department of Human Molecular Genetics and Biochemistry, Sackler School of Medicine, Tel Aviv University, 6997801, Tel-Aviv, Israel
- Department of Pathology, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
| | - Yair Pozniak
- Department of Human Molecular Genetics and Biochemistry, Sackler School of Medicine, Tel Aviv University, 6997801, Tel-Aviv, Israel
| | - Anat Nussbaum-Shochat
- Department of Microbiology and Molecular Genetics, IMRIC, The Hebrew University Faculty of Medicine, P.O.Box 12272, 91120, Jerusalem, Israel
| | - Ora Schueler-Furman
- Department of Microbiology and Molecular Genetics, IMRIC, The Hebrew University Faculty of Medicine, P.O.Box 12272, 91120, Jerusalem, Israel
| | - Tamar Geiger
- Department of Human Molecular Genetics and Biochemistry, Sackler School of Medicine, Tel Aviv University, 6997801, Tel-Aviv, Israel
- Department of Molecular Cell Biology, Weizmann Institute of Science, 76100001, Rehovot, Israel
| | - Orna Amster-Choder
- Department of Microbiology and Molecular Genetics, IMRIC, The Hebrew University Faculty of Medicine, P.O.Box 12272, 91120, Jerusalem, Israel.
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2
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Zhang B, Yang H, Wu Z, Pan J, Li S, Chen L, Cai X, Liu Z, Zheng Y. Spatiotemporal Gene Expression by a Genetic Circuit for Chemical Production in Escherichia coli. ACS Synth Biol 2023; 12:768-779. [PMID: 36821871 DOI: 10.1021/acssynbio.2c00568] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/25/2023]
Abstract
Gene expression in spatiotemporal distribution improves the ability of cells to respond to changing environments. For microbial cell factories in artificial environments, reconstruction of the target compound's biosynthetic pathway in a new spatiotemporal dimension/scale promotes the production of chemicals. Here, a genetic circuit based on the Esa quorum sensing and lac operon was designed to achieve the dynamic temporal gene expression. Meanwhile, the pathway was regulated by an l-cysteine-specific sensor and relocalized to the plasma membrane for further flux enhancement to l-cysteine and toxicity reduction on a spatial scale. Finally, the integrated spatiotemporal regulation circuit for l-cysteine biosynthesis enabled a 14.16 g/L l-cysteine yield in Escherichia coli. Furthermore, this spatiotemporal regulation circuit was also applied in our previously constructed engineered strain for pantothenic acid, methionine, homoserine, and 2-aminobutyric acid production, and the titer increased by 29, 33, 28, and 41%, respectively. These results highlighted the applicability of our spatiotemporal regulation circuit to enhance the performance of microbial cell factories.
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Affiliation(s)
- Bo Zhang
- The National and Local Joint Engineering Research Center for Biomanufacturing of Chiral Chemicals, Zhejiang University of Technology, Hangzhou 310014, P. R. China.,Key Laboratory of Bioorganic Synthesis of Zhejiang Province, College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou 310014, P. R. China
| | - Hui Yang
- The National and Local Joint Engineering Research Center for Biomanufacturing of Chiral Chemicals, Zhejiang University of Technology, Hangzhou 310014, P. R. China.,Key Laboratory of Bioorganic Synthesis of Zhejiang Province, College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou 310014, P. R. China
| | - Zidan Wu
- The National and Local Joint Engineering Research Center for Biomanufacturing of Chiral Chemicals, Zhejiang University of Technology, Hangzhou 310014, P. R. China.,Key Laboratory of Bioorganic Synthesis of Zhejiang Province, College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou 310014, P. R. China
| | - Jiayuan Pan
- The National and Local Joint Engineering Research Center for Biomanufacturing of Chiral Chemicals, Zhejiang University of Technology, Hangzhou 310014, P. R. China.,Key Laboratory of Bioorganic Synthesis of Zhejiang Province, College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou 310014, P. R. China
| | - Shirong Li
- The National and Local Joint Engineering Research Center for Biomanufacturing of Chiral Chemicals, Zhejiang University of Technology, Hangzhou 310014, P. R. China.,Key Laboratory of Bioorganic Synthesis of Zhejiang Province, College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou 310014, P. R. China
| | - Lifeng Chen
- The National and Local Joint Engineering Research Center for Biomanufacturing of Chiral Chemicals, Zhejiang University of Technology, Hangzhou 310014, P. R. China.,Key Laboratory of Bioorganic Synthesis of Zhejiang Province, College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou 310014, P. R. China
| | - Xue Cai
- The National and Local Joint Engineering Research Center for Biomanufacturing of Chiral Chemicals, Zhejiang University of Technology, Hangzhou 310014, P. R. China.,Key Laboratory of Bioorganic Synthesis of Zhejiang Province, College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou 310014, P. R. China
| | - Zhiqiang Liu
- The National and Local Joint Engineering Research Center for Biomanufacturing of Chiral Chemicals, Zhejiang University of Technology, Hangzhou 310014, P. R. China.,Key Laboratory of Bioorganic Synthesis of Zhejiang Province, College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou 310014, P. R. China
| | - Yuguo Zheng
- The National and Local Joint Engineering Research Center for Biomanufacturing of Chiral Chemicals, Zhejiang University of Technology, Hangzhou 310014, P. R. China.,Key Laboratory of Bioorganic Synthesis of Zhejiang Province, College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou 310014, P. R. China
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3
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Irastortza-Olaziregi M, Amster-Choder O. RNA localization in prokaryotes: Where, when, how, and why. WILEY INTERDISCIPLINARY REVIEWS-RNA 2020; 12:e1615. [PMID: 32851805 DOI: 10.1002/wrna.1615] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Revised: 05/27/2020] [Accepted: 06/02/2020] [Indexed: 12/27/2022]
Abstract
Only recently has it been recognized that the transcriptome of bacteria and archaea can be spatiotemporally regulated. All types of prokaryotic transcripts-rRNAs, tRNAs, mRNAs, and regulatory RNAs-may acquire specific localization and these patterns can be temporally regulated. In some cases bacterial RNAs reside in the vicinity of the transcription site, but in many others, transcripts show distinct localizations to the cytoplasm, the inner membrane, or the pole of rod-shaped species. This localization, which often overlaps with that of the encoded proteins, can be achieved either in a translation-dependent or translation-independent fashion. The latter implies that RNAs carry sequence-level features that determine their final localization with the aid of RNA-targeting factors. Localization of transcripts regulates their posttranscriptional fate by affecting their degradation and processing, translation efficiency, sRNA-mediated regulation, and/or propensity to undergo RNA modifications. By facilitating complex assembly and liquid-liquid phase separation, RNA localization is not only a consequence but also a driver of subcellular spatiotemporal complexity. We foresee that in the coming years the study of RNA localization in prokaryotes will produce important novel insights regarding the fundamental understanding of membrane-less subcellular organization and lead to practical outputs with biotechnological and therapeutic implications. This article is categorized under: RNA Export and Localization > RNA Localization Regulatory RNAs/RNAi/Riboswitches > Regulatory RNAs RNA Interactions with Proteins and Other Molecules > Protein-RNA Interactions: Functional Implications.
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Affiliation(s)
- Mikel Irastortza-Olaziregi
- Department of Microbiology and Molecular Genetics, IMRIC, Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Orna Amster-Choder
- Department of Microbiology and Molecular Genetics, IMRIC, Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem, Israel
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4
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Kannaiah S, Livny J, Amster-Choder O. Spatiotemporal Organization of the E. coli Transcriptome: Translation Independence and Engagement in Regulation. Mol Cell 2019; 76:574-589.e7. [PMID: 31540875 DOI: 10.1016/j.molcel.2019.08.013] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Revised: 06/28/2019] [Accepted: 08/13/2019] [Indexed: 12/22/2022]
Abstract
RNA localization in eukaryotes is a mechanism to regulate transcripts fate. Conversely, bacterial transcripts were not assumed to be specifically localized. We previously demonstrated that E. coli mRNAs may localize to where their products localize in a translation-independent manner, thus challenging the transcription-translation coupling extent. However, the scope of RNA localization in bacteria remained unknown. Here, we report the distribution of the E. coli transcriptome between the membrane, cytoplasm, and poles by combining cell fractionation with deep-sequencing (Rloc-seq). Our results reveal asymmetric RNA distribution on a transcriptome-wide scale, significantly correlating with proteome localization and prevalence of translation-independent RNA localization. The poles are enriched with stress-related mRNAs and small RNAs, the latter becoming further enriched upon stress in an Hfq-dependent manner. Genome organization may play a role in localizing membrane protein-encoding transcripts. Our results show an unexpected level of intricacy in bacterial transcriptome organization and highlight the poles as hubs for regulation.
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Affiliation(s)
- Shanmugapriya Kannaiah
- Department of Microbiology and Molecular Genetics, IMRIC, The Hebrew University Faculty of Medicine, P.O. Box 12272, Jerusalem 91120, Israel
| | - Jonathan Livny
- Infectious Disease and Microbiome Program, Broad Institute of MIT and Harvard, 415 Main Street, Cambridge, MA 02140, USA
| | - Orna Amster-Choder
- Department of Microbiology and Molecular Genetics, IMRIC, The Hebrew University Faculty of Medicine, P.O. Box 12272, Jerusalem 91120, Israel.
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5
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Abstract
RNA localization mechanisms have been intensively studied and include localized protection of mRNA from degradation, diffusion-coupled local entrapment of mRNA, and directed transport of mRNAs along the cytoskeleton. While it is well understood how cells utilize these three mechanisms to organize mRNAs within the cytoplasm, a newly appreciated mechanism of RNA localization has emerged in recent years in which mRNAs phase-separate and form liquid-like droplets. mRNAs both contribute to condensation of proteins into liquid-like structures and are themselves regulated by being incorporated into membraneless organelles. This ability to condense into droplets is in many instances contributing to previously appreciated mRNA localization phenomena. Here we review how phase separation enables mRNAs to selectively and efficiently colocalize and be coregulated, allowing control of gene expression in time and space.
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Affiliation(s)
- Erin M Langdon
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA;
| | - Amy S Gladfelter
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA; .,Marine Biological Laboratory, Woods Hole, Massachusetts 02543, USA
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6
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Abstract
Diverse mechanisms and functions of posttranscriptional regulation by small regulatory RNAs and RNA-binding proteins have been described in bacteria. In contrast, little is known about the spatial organization of RNAs in bacterial cells. In eukaryotes, subcellular localization and transport of RNAs play important roles in diverse physiological processes, such as embryonic patterning, asymmetric cell division, epithelial polarity, and neuronal plasticity. It is now clear that bacterial RNAs also can accumulate at distinct sites in the cell. However, due to the small size of bacterial cells, RNA localization and localization-associated functions are more challenging to study in bacterial cells, and the underlying molecular mechanisms of transcript localization are less understood. Here, we review the emerging examples of RNAs localized to specific subcellular locations in bacteria, with indications that subcellular localization of transcripts might be important for gene expression and regulatory processes. Diverse mechanisms for bacterial RNA localization have been suggested, including close association to their genomic site of transcription, or to the localizations of their protein products in translation-dependent or -independent processes. We also provide an overview of the state of the art of technologies to visualize and track bacterial RNAs, ranging from hybridization-based approaches in fixed cells to in vivo imaging approaches using fluorescent protein reporters and/or RNA aptamers in single living bacterial cells. We conclude with a discussion of open questions in the field and ongoing technological developments regarding RNA imaging in eukaryotic systems that might likewise provide novel insights into RNA localization in bacteria.
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7
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Sachdeva G, Myhrvold C, Yin P, Silver PA. Synthetic RNA Scaffolds for Spatial Engineering in Cells. Synth Biol (Oxf) 2018. [DOI: 10.1002/9783527688104.ch13] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Affiliation(s)
- Gairik Sachdeva
- Harvard John A. Paulson School of Engineering and Applied Sciences, 29 Oxford Street; Cambridge MA 02138 USA
- Harvard University; Wyss Institute for Biologically Inspired Engineering, 3 Blackfan Circle; Boston MA 02115 USA
- Harvard Medical School; Department of Systems Biology, 200 Longwood Avenue; Boston MA 02115 USA
| | - Cameron Myhrvold
- Harvard University; Wyss Institute for Biologically Inspired Engineering, 3 Blackfan Circle; Boston MA 02115 USA
- Harvard Medical School; Department of Systems Biology, 200 Longwood Avenue; Boston MA 02115 USA
| | - Peng Yin
- Harvard University; Wyss Institute for Biologically Inspired Engineering, 3 Blackfan Circle; Boston MA 02115 USA
| | - Pamela A. Silver
- Harvard University; Wyss Institute for Biologically Inspired Engineering, 3 Blackfan Circle; Boston MA 02115 USA
- Harvard Medical School; Department of Systems Biology, 200 Longwood Avenue; Boston MA 02115 USA
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8
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van Gijtenbeek LA, Kok J. Illuminating Messengers: An Update and Outlook on RNA Visualization in Bacteria. Front Microbiol 2017; 8:1161. [PMID: 28690601 PMCID: PMC5479882 DOI: 10.3389/fmicb.2017.01161] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2017] [Accepted: 06/07/2017] [Indexed: 01/04/2023] Open
Abstract
To be able to visualize the abundance and spatiotemporal features of RNAs in bacterial cells would permit obtaining a pivotal understanding of many mechanisms underlying bacterial cell biology. The first methods that allowed observing single mRNA molecules in individual cells were introduced by Bertrand et al. (1998) and Femino et al. (1998). Since then, a plethora of techniques to image RNA molecules with the aid of fluorescence microscopy has emerged. Many of these approaches are useful for the large eukaryotic cells but their adaptation to study RNA, specifically mRNA molecules, in bacterial cells progressed relatively slow. Here, an overview will be given of fluorescent techniques that can be used to reveal specific RNA molecules inside fixed and living single bacterial cells. It includes a critical evaluation of their caveats as well as potential solutions.
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Affiliation(s)
- Lieke A van Gijtenbeek
- Department of Molecular Genetics, Faculty of Science and Engineering, University of GroningenGroningen, Netherlands
| | - Jan Kok
- Department of Molecular Genetics, Faculty of Science and Engineering, University of GroningenGroningen, Netherlands
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9
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BiFCROS: A Low-Background Fluorescence Repressor Operator System for Labeling of Genomic Loci. G3-GENES GENOMES GENETICS 2017; 7:1969-1977. [PMID: 28450375 PMCID: PMC5473772 DOI: 10.1534/g3.117.040782] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Fluorescence-based methods are widely used to analyze elementary cell processes such as DNA replication or chromosomal folding and segregation. Labeling DNA with a fluorescent protein allows the visualization of its temporal and spatial organization. One popular approach is FROS (fluorescence repressor operator system). This method specifically labels DNA in vivo through binding of a fusion of a fluorescent protein and a repressor protein to an operator array, which contains numerous copies of the repressor binding site integrated into the genomic site of interest. Bound fluorescent proteins are then visible as foci in microscopic analyses and can be distinguished from the background fluorescence caused by unbound fusion proteins. Even though this method is widely used, no attempt has been made so far to decrease the background fluorescence to facilitate analysis of the actual signal of interest. Here, we present a new method that greatly reduces the background signal of FROS. BiFCROS (Bimolecular Fluorescence Complementation and Repressor Operator System) is based on fusions of repressor proteins to halves of a split fluorescent protein. Binding to a hybrid FROS array results in fluorescence signals due to bimolecular fluorescence complementation. Only proteins bound to the hybrid FROS array fluoresce, greatly improving the signal to noise ratio compared to conventional FROS. We present the development of BiFCROS and discuss its potential to be used as a fast and single-cell readout for copy numbers of genetic loci.
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10
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Kellermann SJ, Rentmeister A. A FACS-based screening strategy to assess sequence-specific RNA-binding of Pumilio protein variants in E. coli. Biol Chem 2017; 398:69-75. [DOI: 10.1515/hsz-2016-0214] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2016] [Accepted: 09/15/2016] [Indexed: 12/22/2022]
Abstract
Abstract
Sequence-specific and programmable binding of proteins to RNA bears the potential to detect and manipulate target RNAs. Applications include analysis of subcellular RNA localization or post-transcriptional regulation but require sequence-specificity to be readily adjustable to any target RNA. The Pumilio homology domain binds an eight nucleotide target sequence in a predictable manner allowing for rational design of variants with new specificities. We describe a high-throughput system for screening Pumilio variants based on fluorescence-activated cell sorting of E. coli. Our approach should help optimizing variants obtained from rational design regarding folding and stability or identifying new variants with alternative binding modes.
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11
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Abstract
Gram-negative and gram-positive bacteria use a variety of enzymatic pathways to degrade mRNAs. Although several recent reviews have outlined these pathways, much less attention has been paid to the regulation of mRNA decay. The functional half-life of a particular mRNA, which affects how much protein is synthesized from it, is determined by a combination of multiple factors. These include, but are not necessarily limited to, (a) stability elements at either the 5' or the 3' terminus, (b) posttranscriptional modifications, (c) ribosome density on individual mRNAs, (d) small regulatory RNA (sRNA) interactions with mRNAs, (e) regulatory proteins that alter ribonuclease binding affinities, (f) the presence or absence of endonucleolytic cleavage sites, (g) control of intracellular ribonuclease levels, and (h) physical location within the cell. Changes in physiological conditions associated with environmental alterations can significantly alter the impact of these factors in the decay of a particular mRNA.
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Affiliation(s)
- Bijoy K Mohanty
- Department of Genetics, University of Georgia, Athens, Georgia 30602;
| | - Sidney R Kushner
- Department of Genetics, University of Georgia, Athens, Georgia 30602;
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12
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Moffitt JR, Pandey S, Boettiger AN, Wang S, Zhuang X. Spatial organization shapes the turnover of a bacterial transcriptome. eLife 2016; 5. [PMID: 27198188 PMCID: PMC4874777 DOI: 10.7554/elife.13065] [Citation(s) in RCA: 103] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2015] [Accepted: 03/20/2016] [Indexed: 12/21/2022] Open
Abstract
Spatial organization of the transcriptome has emerged as a powerful means for regulating the post-transcriptional fate of RNA in eukaryotes; however, whether prokaryotes use RNA spatial organization as a mechanism for post-transcriptional regulation remains unclear. Here we used super-resolution microscopy to image the E. coli transcriptome and observed a genome-wide spatial organization of RNA: mRNAs encoding inner-membrane proteins are enriched at the membrane, whereas mRNAs encoding outer-membrane, cytoplasmic and periplasmic proteins are distributed throughout the cytoplasm. Membrane enrichment is caused by co-translational insertion of signal peptides recognized by the signal-recognition particle. Time-resolved RNA-sequencing revealed that degradation rates of inner-membrane-protein mRNAs are on average greater that those of the other mRNAs and that this selective destabilization of inner-membrane-protein mRNAs is abolished by dissociating the RNA degradosome from the membrane. Together, these results demonstrate that the bacterial transcriptome is spatially organized and suggest that this organization shapes the post-transcriptional dynamics of mRNAs. DOI:http://dx.doi.org/10.7554/eLife.13065.001 Within a cell, molecules of messenger RNA (mRNA) encode the proteins that the cell needs to survive and thrive. The amount of mRNA within a cell therefore plays an important role in determining both the amount and types of proteins that a cell contains and, thus, the behavior of the cell. In eukaryotic organisms, like humans, it has been established that it is not just the amount of mRNA that influences cell behavior, but also where the mRNA molecules are found within the cell. However, in bacteria, which are much smaller than human cells, it has long been believed that the location of an mRNA within the cell does not affect its behavior. Despite this, recent studies that have looked at small numbers of bacterial mRNAs have shown that some of these molecules are found in larger numbers than usual at certain sites inside cells. This suggests that location may actually affect the activity of some bacterial mRNAs. But do similar localization patterns occur for all of the thousands of different mRNAs that bacteria can make? To address this question, Moffitt et al. developed an approach that allows large, defined sets of mRNAs to be imaged in bacteria. Using this approach to study E. coli revealed that a considerable fraction of all the mRNAs that these bacteria can make locate themselves at specific sites within a cell. For example, mRNAs that encode proteins that reside inside the cell’s inner membrane are found enriched at this membrane. This localization also plays an important role in the life of these mRNAs, as they are degraded more quickly than those found elsewhere in the cell. This enhanced degradation rate arises partly because the enzymes that break down mRNA molecules are also found at the membrane. Thus, bacteria can shape the process by which an mRNA is made into protein by controlling where in a cell the mRNA is located. The next steps are to understand why bacteria use cell location to influence the rate of mRNA degradation. DOI:http://dx.doi.org/10.7554/eLife.13065.002
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Affiliation(s)
- Jeffrey R Moffitt
- Howard Hughes Medical Institute, Harvard University, Cambridge, United States.,Department of Chemistry and Chemical Biology, Harvard University, Cambridge, United States
| | - Shristi Pandey
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, United States
| | - Alistair N Boettiger
- Howard Hughes Medical Institute, Harvard University, Cambridge, United States.,Department of Chemistry and Chemical Biology, Harvard University, Cambridge, United States
| | - Siyuan Wang
- Howard Hughes Medical Institute, Harvard University, Cambridge, United States.,Department of Chemistry and Chemical Biology, Harvard University, Cambridge, United States
| | - Xiaowei Zhuang
- Howard Hughes Medical Institute, Harvard University, Cambridge, United States.,Department of Chemistry and Chemical Biology, Harvard University, Cambridge, United States.,Department of Physics, Harvard University, Cambridge, United States
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13
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Holstein JM, Rentmeister A. Current covalent modification methods for detecting RNA in fixed and living cells. Methods 2015; 98:18-25. [PMID: 26615954 DOI: 10.1016/j.ymeth.2015.11.016] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2015] [Revised: 11/20/2015] [Accepted: 11/22/2015] [Indexed: 12/13/2022] Open
Abstract
Labeling RNAs is of particular interest for elucidating localization, transport, and regulation of specific transcripts, ideally in living cells. Numerous methods have been developed ranging from hybridizing probes to genetically encoded reporters and chemo-enzymatic approaches. This review focuses on covalent labeling approaches that rely on the introduction of a small reactive group into the nascent or completed transcript followed by bioorthogonal click chemistry. State of the approaches for labeling RNA in fixed and living cells will be presented and emerging strategies with great potential for application in the complex cellular environment will be discussed.
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Affiliation(s)
- Josephin M Holstein
- Westfälische Wilhelms-Universität Münster, Institute of Biochemistry, 48149 Muenster, Germany
| | - Andrea Rentmeister
- Westfälische Wilhelms-Universität Münster, Institute of Biochemistry, 48149 Muenster, Germany; Cells-in-Motion Cluster of Excellence (EXC 1003 - CiM), University of Muenster, 48149 Muenster, Germany.
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14
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Smolina I, Broude N. 80 RNA labeling and dynamics in live bacterial cells. J Biomol Struct Dyn 2015. [DOI: 10.1080/07391102.2015.1032697] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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15
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Smurthwaite CA, Williams W, Fetsko A, Abbadessa D, Stolp ZD, Reed CW, Dharmawan A, Wolkowicz R. Genetic barcoding with fluorescent proteins for multiplexed applications. J Vis Exp 2015:52452. [PMID: 25938804 PMCID: PMC4541556 DOI: 10.3791/52452] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Fluorescent proteins, fluorescent dyes and fluorophores in general have revolutionized the field of molecular cell biology. In particular, the discovery of fluorescent proteins and their genes have enabled the engineering of protein fusions for localization, the analysis of transcriptional activation and translation of proteins of interest, or the general tracking of individual cells and cell populations. The use of fluorescent protein genes in combination with retroviral technology has further allowed the expression of these proteins in mammalian cells in a stable and reliable manner. Shown here is how one can utilize these genes to give cells within a population of cells their own biosignature. As the biosignature is achieved with retroviral technology, cells are barcoded 'indefinitely'. As such, they can be individually tracked within a mixture of barcoded cells and utilized in more complex biological applications. The tracking of distinct populations in a mixture of cells is ideal for multiplexed applications such as discovery of drugs against a multitude of targets or the activation profile of different promoters. The protocol describes how to elegantly develop and amplify barcoded mammalian cells with distinct genetic fluorescent markers, and how to use several markers at once or one marker at different intensities. Finally, the protocol describes how the cells can be further utilized in combination with cell-based assays to increase the power of analysis through multiplexing.
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16
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Genetically encoded tools for RNA imaging in living cells. Curr Opin Biotechnol 2015; 31:42-9. [DOI: 10.1016/j.copbio.2014.07.012] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Accepted: 07/30/2014] [Indexed: 12/11/2022]
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17
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Abstract
The spectrum of RNA functions in the cell continues to widen and new types of RNA molecules continue to be discovered. However, methods to access and manipulate endogenous RNAs in live cells are limited. Here we describe a universal technique for labeling natural RNAs in live cells with the probes synthesized by the cell. The method is based on fluorescent protein complementation in combination with a split aptamer approach. Two RNA probes containing split aptamer sequences flanked with the antisense RNA target sequences are assembled on the target RNA to form a fluorescent ribonucleoprotein (RNP) complex. The mechanism of complex formation ensures highly sensitive RNA detection allowing visualization of endogenous bacterial mRNAs. We demonstrate the great potential of this method by detecting chromosomally low-level expressed unmodified bacterial mRNA in living bacterial cells. This method holds promise to become a broadly used tool in basic research, and eventually in diagnostics and therapeutics.
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Affiliation(s)
- Irina Smolina
- Department of Biomedical Engineering, Boston University, Boston, MA, 01225, USA,
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18
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Ding Y, Wu F, Tan C. Synthetic Biology: A Bridge between Artificial and Natural Cells. Life (Basel) 2014; 4:1092-116. [PMID: 25532531 PMCID: PMC4284483 DOI: 10.3390/life4041092] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Revised: 12/02/2014] [Accepted: 12/11/2014] [Indexed: 12/24/2022] Open
Abstract
Artificial cells are simple cell-like entities that possess certain properties of natural cells. In general, artificial cells are constructed using three parts: (1) biological membranes that serve as protective barriers, while allowing communication between the cells and the environment; (2) transcription and translation machinery that synthesize proteins based on genetic sequences; and (3) genetic modules that control the dynamics of the whole cell. Artificial cells are minimal and well-defined systems that can be more easily engineered and controlled when compared to natural cells. Artificial cells can be used as biomimetic systems to study and understand natural dynamics of cells with minimal interference from cellular complexity. However, there remain significant gaps between artificial and natural cells. How much information can we encode into artificial cells? What is the minimal number of factors that are necessary to achieve robust functioning of artificial cells? Can artificial cells communicate with their environments efficiently? Can artificial cells replicate, divide or even evolve? Here, we review synthetic biological methods that could shrink the gaps between artificial and natural cells. The closure of these gaps will lead to advancement in synthetic biology, cellular biology and biomedical applications.
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Affiliation(s)
- Yunfeng Ding
- Department of Biomedical Engineering, University of California Davis, One Shields Ave., Davis, CA 95616-5270, USA.
| | - Fan Wu
- Department of Biomedical Engineering, University of California Davis, One Shields Ave., Davis, CA 95616-5270, USA.
| | - Cheemeng Tan
- Department of Biomedical Engineering, University of California Davis, One Shields Ave., Davis, CA 95616-5270, USA.
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19
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Abstract
One of the most important discoveries in the field of microbiology in the last two decades is that bacterial cells have intricate subcellular organization. This understanding has emerged mainly from the depiction of spatial and temporal organization of proteins in specific domains within bacterial cells, e.g., midcell, cell poles, membrane and periplasm. Because translation of bacterial RNA molecules was considered to be strictly coupled to their synthesis, they were not thought to specifically localize to regions outside the nucleoid. However, the increasing interest in RNAs, including non-coding RNAs, encouraged researchers to explore the spatial and temporal localization of RNAs in bacteria. The recent technological improvements in the field of fluorescence microscopy allowed subcellular imaging of RNAs even in the tiny bacterial cells. It has been reported by several groups, including ours that transcripts may specifically localize in such cells. Here we review what is known about localization of RNA and of the pathways that determine RNA fate in bacteria, and discuss the possible cues and mechanisms underlying these distribution patterns.
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Affiliation(s)
- Avi-ad Avraam Buskila
- a Department of Microbiology and Molecular Genetics; IMRIC ; The Hebrew University Faculty of Medicine ; Israel
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20
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Yoshimura H, Ozawa T. Methods of Split Reporter Reconstitution for the Analysis of Biomolecules. CHEM REC 2014; 14:492-501. [DOI: 10.1002/tcr.201402001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2014] [Indexed: 12/31/2022]
Affiliation(s)
- Hideaki Yoshimura
- Department of Chemistry; Graduate School of Science; The University of Tokyo; 7-3-1 Hongo, Bunkyo-ku Tokyo 113-0033 Japan
| | - Takeaki Ozawa
- Department of Chemistry; Graduate School of Science; The University of Tokyo; 7-3-1 Hongo, Bunkyo-ku Tokyo 113-0033 Japan
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21
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Toran P, Smolina I, Driscoll H, Ding F, Sun Y, Cantor CR, Broude NE. Labeling native bacterial RNA in live cells. Cell Res 2014; 24:894-7. [PMID: 24732010 DOI: 10.1038/cr.2014.47] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Affiliation(s)
- Paul Toran
- Cell Biology, Molecular Biology and Biochemistry Program, Boston University, Boston, MA 01225, USA
| | - Irina Smolina
- Department of Biomedical Engineering, Boston University, Boston, MA 01225, USA
| | - Harry Driscoll
- Department of Biomedical Engineering, Boston University, Boston, MA 01225, USA
| | - Feng Ding
- Department of Physics and Astronomy, 118 Kinard Lab, Clemson University, Clemson, SC 29634, USA
| | - Yingjie Sun
- Department of Biomedical Engineering, Boston University, Boston, MA 01225, USA
| | - Charles R Cantor
- Sequenom Inc, 3595 John Hopkins Court, San Diego, CA 92121-1331, USA
| | - Natalia E Broude
- 1] Cell Biology, Molecular Biology and Biochemistry Program, Boston University, Boston, MA 01225, USA [2] Department of Biomedical Engineering, Boston University, Boston, MA 01225, USA
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22
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Pitchiaya S, Heinicke LA, Custer TC, Walter NG. Single molecule fluorescence approaches shed light on intracellular RNAs. Chem Rev 2014; 114:3224-65. [PMID: 24417544 PMCID: PMC3968247 DOI: 10.1021/cr400496q] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- Sethuramasundaram Pitchiaya
- Single Molecule Analysis in Real-Time (SMART)
Center, University of Michigan, Ann Arbor, MI 48109-1055, USA
- Single Molecule Analysis Group, Department of
Chemistry, University of Michigan, Ann Arbor, MI 48109-1055, USA
| | - Laurie A. Heinicke
- Single Molecule Analysis Group, Department of
Chemistry, University of Michigan, Ann Arbor, MI 48109-1055, USA
| | - Thomas C. Custer
- Program in Chemical Biology, University of Michigan,
Ann Arbor, MI 48109-1055, USA
| | - Nils G. Walter
- Single Molecule Analysis in Real-Time (SMART)
Center, University of Michigan, Ann Arbor, MI 48109-1055, USA
- Single Molecule Analysis Group, Department of
Chemistry, University of Michigan, Ann Arbor, MI 48109-1055, USA
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23
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Hadizadeh Yazdi N, Guet CC, Johnson RC, Marko JF. Variation of the folding and dynamics of the Escherichia coli chromosome with growth conditions. Mol Microbiol 2013; 86:1318-33. [PMID: 23078205 DOI: 10.1111/mmi.12071] [Citation(s) in RCA: 108] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/14/2012] [Indexed: 11/30/2022]
Abstract
We examine whether the Escherichia coli chromosome is folded into a self-adherent nucleoprotein complex, or alternately is a confined but otherwise unconstrained self-avoiding polymer. We address this through in vivo visualization, using an inducible GFP fusion to the nucleoid-associated protein Fis to non-specifically decorate the entire chromosome. For a range of different growth conditions, the chromosome is a compact structure that does not fill the volume of the cell, and which moves from the new pole to the cell centre. During rapid growth, chromosome segregation occurs well before cell division, with daughter chromosomes coupled by a thin inter-daughter filament before complete segregation, whereas during slow growth chromosomes stay adjacent until cell division occurs. Image correlation analysis indicates that sub-nucleoid structure is stable on a 1 min timescale, comparable to the timescale for redistribution time measured for GFP-Fis after photobleaching. Optical deconvolution and writhe calculation analysis indicate that the nucleoid has a large-scale coiled organization rather than being an amorphous mass. Our observations are consistent with the chromosome having a self-adherent filament organization.
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24
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Mackie GA. RNase E: at the interface of bacterial RNA processing and decay. Nat Rev Microbiol 2012; 11:45-57. [DOI: 10.1038/nrmicro2930] [Citation(s) in RCA: 236] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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25
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Abstract
Molecular imaging has greatly advanced basic biology and translational medicine through visualization and quantification of single/multiple molecular events temporally and spatially in a cellular context and in living organisms. Aptamers, short single-stranded nucleic acids selected in vitro to bind a broad range of target molecules avidly and specifically, are ideal molecular recognition elements for probe development in molecular imaging. This review summarizes the current state of aptamer-based biosensor development (probe design and imaging modalities) and their application in imaging small molecules, nucleic acids and proteins mostly in a cellular context with some animal studies. The article is concluded with a brief discussion on the perspective of aptamer-based molecular imaging.
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Affiliation(s)
- Tianjiao Wang
- Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, IA 50011, USA.
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26
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Govindarajan S, Nevo-Dinur K, Amster-Choder O. Compartmentalization and spatiotemporal organization of macromolecules in bacteria. FEMS Microbiol Rev 2012; 36:1005-22. [DOI: 10.1111/j.1574-6976.2012.00348.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2011] [Revised: 06/27/2012] [Accepted: 06/28/2012] [Indexed: 12/18/2022] Open
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27
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Norris V, Menu-Bouaouiche L, Becu JM, Legendre R, Norman R, Rosenzweig JA. Hyperstructure interactions influence the virulence of the type 3 secretion system in yersiniae and other bacteria. Appl Microbiol Biotechnol 2012; 96:23-36. [PMID: 22949045 DOI: 10.1007/s00253-012-4325-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2012] [Revised: 07/18/2012] [Accepted: 07/18/2012] [Indexed: 01/06/2023]
Abstract
A paradigm shift in our thinking about the intricacies of the host-parasite interaction is required that considers bacterial structures and their relationship to bacterial pathogenesis. It has been proposed that interactions between extended macromolecular assemblies, termed hyperstructures (which include multiprotein complexes), determine bacterial phenotypes. In particular, it has been proposed that hyperstructures can alter virulence. Two such hyperstructures have been characterized in both pathogenic and nonpathogenic bacteria. Present within a number of both human and plant Gram-negative pathogens is the type 3 secretion system (T3SS) injectisome which in some bacteria serves to inject toxic effector proteins directly into targeted host cells resulting in their paralysis and eventual death (but which in other bacteria prevents the death of the host). The injectisome itself comprises multiple protein subunits, which are all essential for its function. The degradosome is another multiprotein complex thought to be involved in cooperative RNA decay and processing of mRNA transcripts and has been very well characterized in nonpathogenic Escherichia coli. Recently, experimental evidence has suggested that a degradosome exists in the yersiniae as well and that its interactions within the pathogens modulate their virulence. Here, we explore the possibility that certain interactions between hyperstructures, like the T3SS and the degradosome, can ultimately influence the virulence potential of the pathogen based upon the physical locations of hyperstructures within the cell.
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Affiliation(s)
- Vic Norris
- Department of Biology, University of Rouen, 76821 Mont-Saint-Aignan, Rouen, France.
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28
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Nevo-Dinur K, Govindarajan S, Amster-Choder O. Subcellular localization of RNA and proteins in prokaryotes. Trends Genet 2012; 28:314-22. [DOI: 10.1016/j.tig.2012.03.008] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2011] [Revised: 03/15/2012] [Accepted: 03/19/2012] [Indexed: 10/28/2022]
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29
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Trevors JT. Physical and biochemical nature of the bacterial cytoplasm: movement and localization of mRNA and the 30S subunits of ribosomes. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2012; 109:1-5. [PMID: 22710107 DOI: 10.1016/j.pbiomolbio.2012.01.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2011] [Accepted: 01/30/2012] [Indexed: 11/25/2022]
Abstract
There is a paucity of knowledge on how mRNA transcripts in the spatially crowded, but molecularly organized bacterial cytoplasm contact the 30S ribosomal subunits. Does simple diffusion in the cytoplasm account for transcript-ribosome interactions given that a large number of ribosomes (e.g., about 72,000 in Escherichia coli during exponential growth) can be present in the cytoplasm? Or are undiscovered mechanisms present where specific transcripts are directed to specific ribosomes at specific cytoplasmic locations, while others are mobilized in a random manner? Moreover, is it possible that cytoplasmic mobilization occurs in bacteria, driven possibly by thermal infrared (IR) radiation and the generation of exclusion zone (EZ) water? These aspects will be discussed in this article and hypotheses presented.
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Affiliation(s)
- J T Trevors
- School of Environmental Sciences, Laboratory of Microbiology, University of Guelph, Guelph, Ontario N1G 2W1, Canada.
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30
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Russell JH, Keiler KC. RNA visualization in bacteria by fluorescence in situ hybridization. Methods Mol Biol 2012; 905:87-95. [PMID: 22736000 DOI: 10.1007/978-1-61779-949-5_7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Detecting localized RNA in bacteria is difficult due to the properties of RNA and the small size of the cell. Fluorescence in situ hybridization (FISH) has been an invaluable method for detecting and imaging RNA. In FISH, RNA is fixed in its native subcellular position through chemical cross-linking. An oligonucleotide probe conjugated to a fluorophore is annealed to the target RNA, and the target RNA/probe hybrid is visualized using fluorescence microscopy. This chapter describes the use of FISH to visualize tmRNA, a regulatory RNA required for trans-translation. The method can be adapted to visualize the localization of other regulatory and messenger RNAs as well.
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Affiliation(s)
- Jay H Russell
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, MD, USA.
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31
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Harriman OLJ, Leake MC. Single molecule experimentation in biological physics: exploring the living component of soft condensed matter one molecule at a time. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2011; 23:503101. [PMID: 22067659 DOI: 10.1088/0953-8984/23/50/503101] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The soft matter of biological systems consists of mesoscopic length scale building blocks, composed of a variety of different types of biological molecules. Most single biological molecules are so small that 1 billion would fit on the full-stop at the end of this sentence, but collectively they carry out the vital activities in living cells whose length scale is at least three orders of magnitude greater. Typically, the number of molecules involved in any given cellular process at any one time is relatively small, and so real physiological events may often be dominated by stochastics and fluctuation behaviour at levels comparable to thermal noise, and are generally heterogeneous in nature. This challenging combination of heterogeneity and stochasticity is best investigated experimentally at the level of single molecules, as opposed to more conventional bulk ensemble-average techniques. In recent years, the use of such molecular experimental approaches has become significantly more widespread in research laboratories around the world. In this review we discuss recent experimental approaches in biological physics which can be applied to investigate the living component of soft condensed matter to a precision of a single molecule.
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Affiliation(s)
- O L J Harriman
- Clarendon Laboratory, Department of Physics, Oxford University, Parks Road, Oxford OX1 3PU, UK
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32
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Ingerson-Mahar M, Gitai Z. A growing family: the expanding universe of the bacterial cytoskeleton. FEMS Microbiol Rev 2011; 36:256-66. [PMID: 22092065 DOI: 10.1111/j.1574-6976.2011.00316.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2011] [Revised: 11/02/2011] [Accepted: 11/10/2011] [Indexed: 12/16/2022] Open
Abstract
Cytoskeletal proteins are important mediators of cellular organization in both eukaryotes and bacteria. In the past, cytoskeletal studies have largely focused on three major cytoskeletal families, namely the eukaryotic actin, tubulin, and intermediate filament (IF) proteins and their bacterial homologs MreB, FtsZ, and crescentin. However, mounting evidence suggests that these proteins represent only the tip of the iceberg, as the cellular cytoskeletal network is far more complex. In bacteria, each of MreB, FtsZ, and crescentin represents only one member of large families of diverse homologs. There are also newly identified bacterial cytoskeletal proteins with no eukaryotic homologs, such as WACA proteins and bactofilins. Furthermore, there are universally conserved proteins, such as the metabolic enzyme CtpS, that assemble into filamentous structures that can be repurposed for structural cytoskeletal functions. Recent studies have also identified an increasing number of eukaryotic cytoskeletal proteins that are unrelated to actin, tubulin, and IFs, such that expanding our understanding of cytoskeletal proteins is advancing the understanding of the cell biology of all organisms. Here, we summarize the recent explosion in the identification of new members of the bacterial cytoskeleton and describe a hypothesis for the evolution of the cytoskeleton from self-assembling enzymes.
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Abstract
The bacterial RNA network includes most of the same components found in eukaryotes, and many of the interactions that under lie transcription, RNA processing and stability, translation, and protein secretion are conserved. The major difference is that all of these functions take place in a single cellular compartment. In spite of the absence of membrane-bound organelles, or in some cases because of it, key components of the RNA network are localized to specific subcellular spaces or structures to ensure proper processing and regulation. This chapter focuses on what is known about subcellular localization of the bacterial RNA network and what insights localization provides to regulation of the RNA infrastructure of the cell.
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34
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Zeng J, Wang J, Gao W, Mohammadreza A, Kelbauskas L, Zhang W, Johnson RH, Meldrum DR. Quantitative single-cell gene expression measurements of multiple genes in response to hypoxia treatment. Anal Bioanal Chem 2011; 401:3-13. [PMID: 21614642 DOI: 10.1007/s00216-011-5084-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2011] [Revised: 04/26/2011] [Accepted: 04/29/2011] [Indexed: 01/28/2023]
Abstract
Cell-to-cell heterogeneity in gene transcription plays a central role in a variety of vital cell processes. To quantify gene expression heterogeneity patterns among cells and to determine their biological significance, methods to measure gene expression levels at the single-cell level are highly needed. We report an experimental technique based on the DNA-intercalating fluorescent dye SYBR green for quantitative expression level analysis of up to ten selected genes in single mammalian cells. The method features a two-step procedure consisting of a step to isolate RNA from a single mammalian cell, synthesize cDNA from it, and a qPCR step. We applied the method to cell populations exposed to hypoxia, quantifying expression levels of seven different genes spanning a wide dynamic range of expression in randomly picked single cells. In the experiment, 72 single Barrett's esophageal epithelial (CP-A) cells, 36 grown under normal physiological conditions (controls) and 36 exposed to hypoxia for 30 min, were randomly collected and used for measuring the expression levels of 28S rRNA, PRKAA1, GAPDH, Angptl4, MT3, PTGES, and VEGFA genes. The results demonstrate that the method is sensitive enough to measure alterations in gene expression at the single-cell level, clearly showing heterogeneity within a cell population. We present technical details of the method development and implementation, and experimental results obtained by use of the procedure. We expect the advantages of this technique will facilitate further developments and advances in the field of single-cell gene expression profiling on a nanotechnological scale, and eventually as a tool for future point-of-care medical applications.
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Affiliation(s)
- Jia Zeng
- Center for Biosignatures Discovery Automation, The Biodesign Institute, Arizona State University, Tempe, AZ 85287-6501, USA
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35
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Broude NE. Analysis of RNA localization and metabolism in single live bacterial cells: achievements and challenges. Mol Microbiol 2011; 80:1137-47. [DOI: 10.1111/j.1365-2958.2011.07652.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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36
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Kim MC, Isenberg BC, Sutin J, Meller A, Wong JY, Klapperich CM. Programmed trapping of individual bacteria using micrometre-size sieves. LAB ON A CHIP 2011; 11:1089-95. [PMID: 21293825 DOI: 10.1039/c0lc00362j] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Monitoring the real-time behavior of spatial arrays of single living bacteria cells is only achieved with much experimental difficulty due to the small size and mobility of the cells. To address this problem, we have designed and constructed a simple microfluidic device capable of trapping single bacteria cells in spatially well-defined locations without the use of chemical surface treatments. The device exploits hydrodynamics to slow down and trap cells flowing near a narrow aperture. We have modeled this system numerically by approximating the motion of Escherichia coli cells as rigid 3-D ellipsoids. The numerical predictions for the speed and efficiency of trapping were tested by fabricating the devices and imaging GFP expressing E. coli at a high spatio-temporal resolution. We find that our numerical simulations agree well with the actual cell flow for varying trap geometries. The trapped cells are optically accessible, and combined with our ability to predict their spatial location we demonstrate the ease of this method for monitoring multiple single cells over a time course. The simplicity of the design, inexpensive materials and straightforward fabrication make it an accessible tool for any systems biology laboratory.
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Affiliation(s)
- Min-Cheol Kim
- Department of Biomedical Engineering, Boston University, 44 Cummington St., Boston, MA 02215, USA
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37
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Nevo-Dinur K, Nussbaum-Shochat A, Ben-Yehuda S, Amster-Choder O. Translation-independent localization of mRNA in E. coli. Science 2011; 331:1081-4. [PMID: 21350180 DOI: 10.1126/science.1195691] [Citation(s) in RCA: 204] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Understanding the organization of a bacterial cell requires the elucidation of the mechanisms by which proteins localize to particular subcellular sites. Thus far, such mechanisms have been suggested to rely on embedded features of the localized proteins. Here, we report that certain messenger RNAs (mRNAs) in Escherichia coli are targeted to the future destination of their encoded proteins, cytoplasm, poles, or inner membrane in a translation-independent manner. Cis-acting sequences within the transmembrane-coding sequence of the membrane proteins are necessary and sufficient for mRNA targeting to the membrane. In contrast to the view that transcription and translation are coupled in bacteria, our results show that, subsequent to their synthesis, certain mRNAs are capable of migrating to particular domains in the cell where their future protein products are required.
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Affiliation(s)
- Keren Nevo-Dinur
- Department of Microbiology and Molecular Genetics, Institute for Medical Research Israel-Canada, The Hebrew University Faculty of Medicine, Post Office Box 12272, Jerusalem 91120, Israel
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38
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RNA Detection in Live Bacterial Cells Using Fluorescent Protein Complementation Triggered by Interaction of Two RNA Aptamers with Two RNA-Binding Peptides. Pharmaceuticals (Basel) 2011. [PMCID: PMC4053799 DOI: 10.3390/ph4030494] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Many genetic and infectious diseases can be targeted at the RNA level as RNA is more accessible than DNA. We seek to develop new approaches for detection and tracking RNA in live cells, which is necessary for RNA-based diagnostics and therapy. We recently described a method for RNA visualization in live bacterial cells based on fluorescent protein complementation [1-3]. The RNA is tagged with an RNA aptamer that binds an RNA-binding protein with high affinity. This RNA-binding protein is expressed as two split fragments fused to the fragments of a split fluorescent protein. In the presence of RNA the fragments of the RNA-binding protein bind the aptamer and bring together the fragments of the fluorescent protein, which results in its re-assembly and fluorescence development [1-3]. Here we describe a new version of the RNA labeling method where fluorescent protein complementation is triggered by paired interactions of two different closely-positioned RNA aptamers with two different RNA-binding viral peptides. The new method, which has been developed in bacteria as a model system, uses a smaller ribonucleoprotein complementation complex, as compared with the method using split RNA-binding protein, and it can potentially be applied to a broad variety of RNA targets in both prokaryotic and eukaryotic cells. We also describe experiments exploring background fluorescence in these RNA detection systems and conditions that improve the signal-to-background ratio.
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39
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Keiler KC. RNA localization in bacteria. Curr Opin Microbiol 2011; 14:155-9. [PMID: 21354362 DOI: 10.1016/j.mib.2011.01.009] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2010] [Accepted: 01/28/2011] [Indexed: 11/24/2022]
Abstract
Bacteria localize proteins and DNA regions to specific subcellular sites, and several recent publications show that RNAs are localized within the cell as well. Localization of tmRNA and some mRNAs indicates that RNAs can be sequestered at specific sites by RNA binding proteins, or can be trapped at the location where they are transcribed. Although the functions of RNA localization are not yet completely understood, it appears that one function of RNA localization is to regulate RNA abundance by controlling access to nucleases. New techniques for visualizing RNAs will likely lead to increased examination of spatial control of RNAs and the role this control plays in the regulation of gene expression and bacterial physiology.
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Affiliation(s)
- Kenneth C Keiler
- Department of Biochemistry and Molecular Biology, Penn State University, 401 Althouse Laboratory, University Park, PA 16802,
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40
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41
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Spatial organization of the flow of genetic information in bacteria. Nature 2010; 466:77-81. [PMID: 20562858 PMCID: PMC2896451 DOI: 10.1038/nature09152] [Citation(s) in RCA: 290] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2009] [Accepted: 04/28/2010] [Indexed: 11/10/2022]
Abstract
Eukaryotic cells spatially organize mRNA processes such as translation and mRNA decay. Much less is clear in bacterial cells where the spatial distribution of mature mRNA remains ambiguous. Using a sensitive, quantitative fluorescence in situ hybridization based-method, we show here that in Caulobacter crescentus and Escherichia coli, chromosomally-expressed mRNAs largely display limited dispersion from their site of transcription during their lifetime. We estimate apparent diffusion coefficients at least 2 orders of magnitude lower than expected for freely diffusing mRNA, and provide evidence in C. crescentus that this mRNA localization restricts ribosomal mobility. Furthermore, C. crescentus RNase E appears associated with the DNA independently of its mRNA substrates. Collectively, our findings reveal that bacteria can spatially organize translation and potentially mRNA decay by using the chromosome layout as a template. This chromosome-centric organization has important implications for cellular physiology and for our understanding of gene expression in bacteria.
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