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Su Y, Wu J, Chen W, Shan J, Chen D, Zhu G, Ge S, Liu Y. Spliceosomal snRNAs, the Essential Players in pre-mRNA Processing in Eukaryotic Nucleus: From Biogenesis to Functions and Spatiotemporal Characteristics. Adv Biol (Weinh) 2024:e2400006. [PMID: 38797893 DOI: 10.1002/adbi.202400006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2024] [Revised: 04/30/2024] [Indexed: 05/29/2024]
Abstract
Spliceosomal small nuclear RNAs (snRNAs) are a fundamental class of non-coding small RNAs abundant in the nucleoplasm of eukaryotic cells, playing a crucial role in splicing precursor messenger RNAs (pre-mRNAs). They are transcribed by DNA-dependent RNA polymerase II (Pol II) or III (Pol III), and undergo subsequent processing and 3' end cleavage to become mature snRNAs. Numerous protein factors are involved in the transcription initiation, elongation, termination, splicing, cellular localization, and terminal modification processes of snRNAs. The transcription and processing of snRNAs are regulated spatiotemporally by various mechanisms, and the homeostatic balance of snRNAs within cells is of great significance for the growth and development of organisms. snRNAs assemble with specific accessory proteins to form small nuclear ribonucleoprotein particles (snRNPs) that are the basal components of spliceosomes responsible for pre-mRNA maturation. This article provides an overview of the biological functions, biosynthesis, terminal structure, and tissue-specific regulation of snRNAs.
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Affiliation(s)
- Yuan Su
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Life Science and Technology, Guangxi University, Nanning, Guangxi, 530004, China
| | - Jiaming Wu
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Life Science and Technology, Guangxi University, Nanning, Guangxi, 530004, China
| | - Wei Chen
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Life Science and Technology, Guangxi University, Nanning, Guangxi, 530004, China
| | - Junling Shan
- Department of basic medicine, Guangxi Medical University of Nursing College, Nanning, Guangxi, 530021, China
| | - Dan Chen
- Ruikang Hospital Affiliated to Guangxi University of Chinese Medicine, Nanning, Guangxi, 530011, China
| | - Guangyu Zhu
- Guangxi Medical University Hospital of Stomatology, Nanning, Guangxi, 530021, China
| | - Shengchao Ge
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Life Science and Technology, Guangxi University, Nanning, Guangxi, 530004, China
| | - Yunfeng Liu
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Life Science and Technology, Guangxi University, Nanning, Guangxi, 530004, China
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2
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Peleke FF, Zumkeller SM, Gültas M, Schmitt A, Szymański J. Deep learning the cis-regulatory code for gene expression in selected model plants. Nat Commun 2024; 15:3488. [PMID: 38664394 PMCID: PMC11045779 DOI: 10.1038/s41467-024-47744-0] [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: 04/28/2023] [Accepted: 04/09/2024] [Indexed: 04/28/2024] Open
Abstract
Elucidating the relationship between non-coding regulatory element sequences and gene expression is crucial for understanding gene regulation and genetic variation. We explored this link with the training of interpretable deep learning models predicting gene expression profiles from gene flanking regions of the plant species Arabidopsis thaliana, Solanum lycopersicum, Sorghum bicolor, and Zea mays. With over 80% accuracy, our models enabled predictive feature selection, highlighting e.g. the significant role of UTR regions in determining gene expression levels. The models demonstrated remarkable cross-species performance, effectively identifying both conserved and species-specific regulatory sequence features and their predictive power for gene expression. We illustrated the application of our approach by revealing causal links between genetic variation and gene expression changes across fourteen tomato genomes. Lastly, our models efficiently predicted genotype-specific expression of key functional gene groups, exemplified by underscoring known phenotypic and metabolic differences between Solanum lycopersicum and its wild, drought-resistant relative, Solanum pennellii.
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Affiliation(s)
- Fritz Forbang Peleke
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Corrensstraße 3, D-06466 Seeland, OT, Gatersleben, Germany
| | - Simon Maria Zumkeller
- Institute of Bio- and Geosciences, IBG-4: Bioinformatics, Forschungszentrum Jülich, D-52428, Jülich, Germany
- Cluster of Excellence on Plant Sciences (CEPLAS), Heinrich-Heine-Universität Düsseldorf, 40225, Düsseldorf, Germany
| | - Mehmet Gültas
- Faculty of Agriculture, South Westphalia University of Applied Sciences, Soest, 59494, Germany
| | - Armin Schmitt
- Breeding Informatics Group, University of Göttingen, Göttingen, 37075, Germany
- Center of Integrated Breeding Research (CiBreed), Göttingen, 37075, Germany
| | - Jędrzej Szymański
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Corrensstraße 3, D-06466 Seeland, OT, Gatersleben, Germany.
- Institute of Bio- and Geosciences, IBG-4: Bioinformatics, Forschungszentrum Jülich, D-52428, Jülich, Germany.
- Cluster of Excellence on Plant Sciences (CEPLAS), Heinrich-Heine-Universität Düsseldorf, 40225, Düsseldorf, Germany.
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3
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Song E, Han S, Hohng S, Kang C. Compatibility of termination mechanisms in bacterial transcription with inference on eukaryotic models. Biochem Soc Trans 2024; 52:887-897. [PMID: 38533838 DOI: 10.1042/bst20231229] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2024] [Revised: 03/18/2024] [Accepted: 03/18/2024] [Indexed: 03/28/2024]
Abstract
Transcription termination has evolved to proceed through diverse mechanisms. For several classes of terminators, multiple models have been debatably proposed. Recent single-molecule studies on bacterial terminators have resolved several long-standing controversies. First, termination mode or outcome is twofold rather than single. RNA is released alone before DNA or together with DNA from RNA polymerase (RNAP), i.e. with RNA release for termination, RNAP retains on or dissociates off DNA, respectively. The concomitant release, described in textbooks, results in one-step decomposition of transcription complexes, and this 'decomposing termination' prevails at ρ factor-dependent terminators. Contrastingly, the sequential release was recently discovered abundantly from RNA hairpin-dependent intrinsic terminations. RNA-only release allows RNAP to diffuse on DNA in both directions and recycle for reinitiation. This 'recycling termination' enables one-dimensional reinitiation, which would be more expeditious than three-dimensional reinitiation by RNAP dissociated at decomposing termination. Second, while both recycling and decomposing terminations occur at a hairpin-dependent terminator, four termination mechanisms compatibly operate at a ρ-dependent terminator with ρ in alternative modes and even intrinsically without ρ. RNA-bound catch-up ρ mediates recycling termination first and decomposing termination later, while RNAP-prebound stand-by ρ invokes only decomposing termination slowly. Without ρ, decomposing termination occurs slightly and sluggishly. These four mechanisms operate on distinct timescales, providing orderly fail-safes. The stand-by mechanism is benefited by terminational pause prolongation and modulated by accompanying riboswitches more greatly than the catch-up mechanisms. Conclusively, any mechanism alone is insufficient to perfect termination, and multiple mechanisms operate compatibly to achieve maximum possible efficiency under separate controls.
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Affiliation(s)
- Eunho Song
- Department of Physics and Astronomy, and Institute of Applied Physics, Seoul National University, Seoul 08826, Republic of Korea
| | - Sun Han
- Department of Physics and Astronomy, and Institute of Applied Physics, Seoul National University, Seoul 08826, Republic of Korea
| | - Sungchul Hohng
- Department of Physics and Astronomy, and Institute of Applied Physics, Seoul National University, Seoul 08826, Republic of Korea
| | - Changwon Kang
- Department of Biological Sciences, and KAIST Stem Cell Center, Korea Advanced Institute of Science and Technology, Daejeon 34141, Republic of Korea
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4
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Chen Q, Li D, Jiang L, Wu Y, Yuan H, Shi G, Liu F, Wu P, Jiang K. Biological functions and clinical significance of tRNA-derived small fragment (tsRNA) in tumors: Current state and future perspectives. Cancer Lett 2024; 587:216701. [PMID: 38369004 DOI: 10.1016/j.canlet.2024.216701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Revised: 01/30/2024] [Accepted: 01/31/2024] [Indexed: 02/20/2024]
Abstract
A new class of noncoding RNAs, tsRNAs are not only abundant in humans but also have high tissue specificity. Recently, an increasing number of studies have explored the correlations between tsRNAs and tumors, showing that tsRNAs can affect biological behaviors of tumor cells, such as proliferation, apoptosis and metastasis, by modulating protein translation, RNA transcription or posttranscriptional regulation. In addition, tsRNAs are widely distributed and stably expressed, which endows them with broad application prospects in diagnosing and predicting the prognosis of tumors, and they are expected to become new biomarkers. However, notably, the current research on tsRNAs still faces problems that need to be solved. In this review, we describe the characteristics of tsRNAs as well as their unique features and functions in tumors. Moreover, we also discuss the potential opportunities and challenges in clinical applications and research of tsRNAs.
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Affiliation(s)
- Qun Chen
- Pancreas Center, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Danrui Li
- Pancreas Center, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Luyang Jiang
- Pancreas Center, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Yang Wu
- Pancreas Center, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Hao Yuan
- Pancreas Center, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Guodong Shi
- Pancreas Center, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Fengyuan Liu
- Pancreas Center, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Pengfei Wu
- Pancreas Center, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China.
| | - Kuirong Jiang
- Pancreas Center, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China.
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Jacobs RQ, Schneider DA. Transcription elongation mechanisms of RNA polymerases I, II, and III and their therapeutic implications. J Biol Chem 2024; 300:105737. [PMID: 38336292 PMCID: PMC10907179 DOI: 10.1016/j.jbc.2024.105737] [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: 11/10/2023] [Revised: 01/30/2024] [Accepted: 02/01/2024] [Indexed: 02/12/2024] Open
Abstract
Transcription is a tightly regulated, complex, and essential cellular process in all living organisms. Transcription is comprised of three steps, transcription initiation, elongation, and termination. The distinct transcription initiation and termination mechanisms of eukaryotic RNA polymerases I, II, and III (Pols I, II, and III) have long been appreciated. Recent methodological advances have empowered high-resolution investigations of the Pols' transcription elongation mechanisms. Here, we review the kinetic similarities and differences in the individual steps of Pol I-, II-, and III-catalyzed transcription elongation, including NTP binding, bond formation, pyrophosphate release, and translocation. This review serves as an important summation of Saccharomyces cerevisiae (yeast) Pol I, II, and III kinetic investigations which reveal that transcription elongation by the Pols is governed by distinct mechanisms. Further, these studies illustrate how basic, biochemical investigations of the Pols can empower the development of chemotherapeutic compounds.
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Affiliation(s)
- Ruth Q Jacobs
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - David A Schneider
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, Alabama, USA.
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Yang ZX, Fu YW, Zhao JJ, Zhang F, Li SA, Zhao M, Wen W, Zhang L, Cheng T, Zhang JP, Zhang XB. Superior Fidelity and Distinct Editing Outcomes of SaCas9 Compared with SpCas9 in Genome Editing. GENOMICS, PROTEOMICS & BIOINFORMATICS 2023; 21:1206-1220. [PMID: 36549468 PMCID: PMC11082263 DOI: 10.1016/j.gpb.2022.12.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Revised: 11/09/2022] [Accepted: 12/13/2022] [Indexed: 12/24/2022]
Abstract
A series of clustered regularly interspaced short palindromic repeats (CRISPR)-CRISPR associated protein 9 (Cas9) systems have been engineered for genome editing. The most widely used Cas9 is SpCas9 from Streptococcus pyogenes and SaCas9 from Staphylococcus aureus. However, a comparison of their detailed gene editing outcomes is still lacking. By characterizing the editing outcomes of 11 sites in human induced pluripotent stem cells (iPSCs) and K562 cells, we found that SaCas9 could edit the genome with greater efficiencies than SpCas9. We also compared the effects of spacer lengths of single-guide RNAs (sgRNAs; 18-21 nt for SpCas9 and 19-23 nt for SaCas9) and found that the optimal spacer lengths were 20 nt and 21 nt for SpCas9 and SaCas9, respectively. However, the optimal spacer length for a particular sgRNA was 18-21 nt for SpCas9 and 21-22 nt for SaCas9. Furthermore, SpCas9 exhibited a more substantial bias than SaCas9 for nonhomologous end-joining (NHEJ) +1 insertion at the fourth nucleotide upstream of the protospacer adjacent motif (PAM), indicating a characteristic of a staggered cut. Accordingly, editing with SaCas9 led to higher efficiencies of NHEJ-mediated double-stranded oligodeoxynucleotide (dsODN) insertion or homology-directed repair (HDR)-mediated adeno-associated virus serotype 6 (AAV6) donor knock-in. Finally, GUIDE-seq analysis revealed that SaCas9 exhibited significantly reduced off-target effects compared with SpCas9. Our work indicates the superior performance of SaCas9 to SpCas9 in transgene integration-based therapeutic gene editing and the necessity to identify the optimal spacer length to achieve desired editing results.
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Affiliation(s)
- Zhi-Xue Yang
- State Key Laboratory of Experimental Hematology, National Clinical Research Center for Blood Diseases, Haihe Laboratory of Cell Ecosystem, Institute of Hematology & Blood Diseases Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Tianjin 300020, China
| | - Ya-Wen Fu
- State Key Laboratory of Experimental Hematology, National Clinical Research Center for Blood Diseases, Haihe Laboratory of Cell Ecosystem, Institute of Hematology & Blood Diseases Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Tianjin 300020, China
| | - Juan-Juan Zhao
- State Key Laboratory of Experimental Hematology, National Clinical Research Center for Blood Diseases, Haihe Laboratory of Cell Ecosystem, Institute of Hematology & Blood Diseases Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Tianjin 300020, China
| | - Feng Zhang
- State Key Laboratory of Experimental Hematology, National Clinical Research Center for Blood Diseases, Haihe Laboratory of Cell Ecosystem, Institute of Hematology & Blood Diseases Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Tianjin 300020, China
| | - Si-Ang Li
- State Key Laboratory of Experimental Hematology, National Clinical Research Center for Blood Diseases, Haihe Laboratory of Cell Ecosystem, Institute of Hematology & Blood Diseases Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Tianjin 300020, China
| | - Mei Zhao
- State Key Laboratory of Experimental Hematology, National Clinical Research Center for Blood Diseases, Haihe Laboratory of Cell Ecosystem, Institute of Hematology & Blood Diseases Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Tianjin 300020, China
| | - Wei Wen
- State Key Laboratory of Experimental Hematology, National Clinical Research Center for Blood Diseases, Haihe Laboratory of Cell Ecosystem, Institute of Hematology & Blood Diseases Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Tianjin 300020, China
| | - Lei Zhang
- State Key Laboratory of Experimental Hematology, National Clinical Research Center for Blood Diseases, Haihe Laboratory of Cell Ecosystem, Institute of Hematology & Blood Diseases Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Tianjin 300020, China
| | - Tao Cheng
- State Key Laboratory of Experimental Hematology, National Clinical Research Center for Blood Diseases, Haihe Laboratory of Cell Ecosystem, Institute of Hematology & Blood Diseases Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Tianjin 300020, China; Center for Stem Cell Medicine, Chinese Academy of Medical Sciences, Tianjin 300020, China; Department of Stem Cell & Regenerative Medicine, Peking Union Medical College, Tianjin 300020, China
| | - Jian-Ping Zhang
- State Key Laboratory of Experimental Hematology, National Clinical Research Center for Blood Diseases, Haihe Laboratory of Cell Ecosystem, Institute of Hematology & Blood Diseases Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Tianjin 300020, China.
| | - Xiao-Bing Zhang
- State Key Laboratory of Experimental Hematology, National Clinical Research Center for Blood Diseases, Haihe Laboratory of Cell Ecosystem, Institute of Hematology & Blood Diseases Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Tianjin 300020, China.
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Zhou S, Van Bortle K. The Pol III transcriptome: Basic features, recurrent patterns, and emerging roles in cancer. WILEY INTERDISCIPLINARY REVIEWS. RNA 2023; 14:e1782. [PMID: 36754845 PMCID: PMC10498592 DOI: 10.1002/wrna.1782] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2022] [Revised: 01/13/2023] [Accepted: 01/18/2023] [Indexed: 02/10/2023]
Abstract
The RNA polymerase III (Pol III) transcriptome is universally comprised of short, highly structured noncoding RNA (ncRNA). Through RNA-protein interactions, the Pol III transcriptome actuates functional activities ranging from nuclear gene regulation (7SK), splicing (U6, U6atac), and RNA maturation and stability (RMRP, RPPH1, Y RNA), to cytoplasmic protein targeting (7SL) and translation (tRNA, 5S rRNA). In higher eukaryotes, the Pol III transcriptome has expanded to include additional, recently evolved ncRNA species that effectively broaden the footprint of Pol III transcription to additional cellular activities. Newly evolved ncRNAs function as riboregulators of autophagy (vault), immune signaling cascades (nc886), and translation (Alu, BC200, snaR). Notably, upregulation of Pol III transcription is frequently observed in cancer, and multiple ncRNA species are linked to both cancer progression and poor survival outcomes among cancer patients. In this review, we outline the basic features and functions of the Pol III transcriptome, and the evidence for dysregulation and dysfunction for each ncRNA in cancer. When taken together, recurrent patterns emerge, ranging from shared functional motifs that include molecular scaffolding and protein sequestration, overlapping protein interactions, and immunostimulatory activities, to the biogenesis of analogous small RNA fragments and noncanonical miRNAs, augmenting the function of the Pol III transcriptome and further broadening its role in cancer. This article is categorized under: RNA in Disease and Development > RNA in Disease RNA Processing > Processing of Small RNAs RNA Interactions with Proteins and Other Molecules > Protein-RNA Interactions: Functional Implications.
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Affiliation(s)
- Sihang Zhou
- Department of Cell and Developmental Biology, University of Illinois Urbana-Champaign, Urbana, Illinois, USA
| | - Kevin Van Bortle
- Department of Cell and Developmental Biology, University of Illinois Urbana-Champaign, Urbana, Illinois, USA
- Cancer Center at Illinois, University of Illinois Urbana-Champaign, Urbana, Illinois, USA
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8
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Fang R, Chen X, Shen J, Wang B. Targeted mRNA demethylation in Arabidopsis using plant m6A editor. PLANT METHODS 2023; 19:81. [PMID: 37559087 PMCID: PMC10413771 DOI: 10.1186/s13007-023-01053-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Accepted: 07/14/2023] [Indexed: 08/11/2023]
Abstract
BACKGROUND N6-methyladenosine (m6A) is an important epigenetic modification involved in RNA stability and translation regulation. Manipulating the expression of RNA m6A methyltransferases or demethylases makes it difficult to study the effect of specific RNA methylation. RESULTS In this study, we report the development of Plant m6A Editors (PMEs) using dLwaCas13a (from L. wadei) and human m6A demethylase ALKBH5 catalytic domain. PMEs specifically demethylates m6A of targeted mRNAs (WUS, STM, FT, SPL3 and SPL9) to increase mRNAs stability. In addition, we discovered that a double ribozyme system can significantly improve the efficiency of RNA editing. CONCLUSION PMEs specifically demethylates m6A of targeted mRNAs to increase mRNAs stability, suggesting that this engineered tool is instrumental for biotechnological applications.
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Affiliation(s)
- Ruiqiu Fang
- Institute of Maize and Featured Upland Crops, Zhejiang Academy of Agricultural Sciences, Dongyang, 322100, Zhejiang, China.
| | - Xiaolong Chen
- Institute of Maize and Featured Upland Crops, Zhejiang Academy of Agricultural Sciences, Dongyang, 322100, Zhejiang, China
| | - Jie Shen
- Department of Life Sciences, Changzhi University, Changzhi, 046011, Shanxi, China
| | - Bin Wang
- Institute of Vegetables, Zhejiang Academy of Agricultural Sciences, Hangzhou, 310021, Zhejiang, China.
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Kawamata M, Suzuki HI, Kimura R, Suzuki A. Optimization of Cas9 activity through the addition of cytosine extensions to single-guide RNAs. Nat Biomed Eng 2023; 7:672-691. [PMID: 37037965 DOI: 10.1038/s41551-023-01011-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2021] [Accepted: 02/17/2023] [Indexed: 04/12/2023]
Abstract
The precise regulation of the activity of Cas9 is crucial for safe and efficient editing. Here we show that the genome-editing activity of Cas9 can be constrained by the addition of cytosine stretches to the 5'-end of conventional single-guide RNAs (sgRNAs). Such a 'safeguard sgRNA' strategy, which is compatible with Cas12a and with systems for gene activation and interference via CRISPR (clustered regularly interspaced short palindromic repeats), leads to the length-dependent inhibition of the formation of functional Cas9 complexes. Short cytosine extensions reduced p53 activation and cytotoxicity in human pluripotent stem cells, and enhanced homology-directed repair while maintaining bi-allelic editing. Longer extensions further decreased on-target activity yet improved the specificity and precision of mono-allelic editing. By monitoring indels through a fluorescence-based allele-specific system and computational simulations, we identified optimal windows of Cas9 activity for a number of genome-editing applications, including bi-allelic and mono-allelic editing, and the generation and correction of disease-associated single-nucleotide substitutions via homology-directed repair. The safeguard-sgRNA strategy may improve the safety and applicability of genome editing.
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Affiliation(s)
- Masaki Kawamata
- Division of Organogenesis and Regeneration, Medical Institute of Bioregulation, Kyushu University, Fukuoka, Japan.
| | - Hiroshi I Suzuki
- Division of Molecular Oncology, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya, Japan.
- Institute for Glyco-core Research (iGCORE), Nagoya University, Nagoya, Japan.
- Center for One Medicine Innovative Translational Research, Gifu University Institute for Advanced Study, Gifu, Japan.
- David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA, USA.
| | - Ryota Kimura
- Division of Organogenesis and Regeneration, Medical Institute of Bioregulation, Kyushu University, Fukuoka, Japan
| | - Atsushi Suzuki
- Division of Organogenesis and Regeneration, Medical Institute of Bioregulation, Kyushu University, Fukuoka, Japan.
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Pekarsky Y, Balatti V, Croce CM. tRNA-derived fragments (tRFs) in cancer. J Cell Commun Signal 2023; 17:47-54. [PMID: 36036848 PMCID: PMC10030754 DOI: 10.1007/s12079-022-00690-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2022] [Accepted: 08/07/2022] [Indexed: 10/15/2022] Open
Abstract
tRNA fragments (tRNA derived fragments or tRFs) are small single stranded RNA molecules derived from pre-tRNAs and mature tRNAs. tRFs have been known for a number of years, but previously they were believed to be not important products of tRNA degradation. tRFs can be unique, like tRF-1 s, or redundant, like tRF-3 s and tRF-5 s. Scientific interest in tRFs has drastically increased in the last 5 years. Many studies have found that tRFs are differentially expressed in many normal cellular processes as well as in transformed cancer cells. Dysregulation of tRFs expression have been reported in multiple major types of cancer including solid cancers and lymphoid malignancies. However the exact molecular role of these molecules is not entirely clear. A number of studies proposed that tRFs can work as microRNAs by targeting gene expression. Here we discuss recent studies showing differential expression of tRFs in many cancers as well as what is currently known about tRFs biological functions in cancer cells.
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Affiliation(s)
- Yuri Pekarsky
- Department of Cancer Biology and Genetics, Comprehensive Cancer Center, The Ohio State University, Biomedical Research Tower, Room 1082, 460 West 12th Avenue, Columbus, OH, 43210, USA.
| | - Veronica Balatti
- Department of Cancer Biology and Genetics, Comprehensive Cancer Center, The Ohio State University, Biomedical Research Tower, Room 1082, 460 West 12th Avenue, Columbus, OH, 43210, USA
| | - Carlo M Croce
- Department of Cancer Biology and Genetics, Comprehensive Cancer Center, The Ohio State University, Biomedical Research Tower, Room 1082, 460 West 12th Avenue, Columbus, OH, 43210, USA.
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11
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Dremel SE, Jimenez AR, Tucker JM. "Transfer" of power: The intersection of DNA virus infection and tRNA biology. Semin Cell Dev Biol 2023; 146:31-39. [PMID: 36682929 PMCID: PMC10101907 DOI: 10.1016/j.semcdb.2023.01.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Revised: 01/17/2023] [Accepted: 01/17/2023] [Indexed: 01/21/2023]
Abstract
Transfer RNAs (tRNAs) are at the heart of the molecular biology central dogma, functioning to decode messenger RNAs into proteins. As obligate intracellular parasites, viruses depend on the host translation machinery, including host tRNAs. Thus, the ability of a virus to fine-tune tRNA expression elicits the power to impact the outcome of infection. DNA viruses commonly upregulate the output of RNA polymerase III (Pol III)-dependent transcripts, including tRNAs. Decades after these initial discoveries we know very little about how mature tRNA pools change during viral infection, as tRNA sequencing methodology has only recently reached proficiency. Here, we review perturbation of tRNA biogenesis by DNA virus infection, including an emerging player called tRNA-derived fragments (tRFs). We discuss how tRNA dysregulation shifts the power landscape between the host and virus, highlighting the potential for tRNA-based antivirals as a future therapeutic.
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Affiliation(s)
- Sarah E Dremel
- HIV and AIDS Malignancy Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Ariana R Jimenez
- Interdisciplinary Graduate Program in Immunology, University of Iowa, Iowa City, IA, USA
| | - Jessica M Tucker
- Department of Microbiology and Immunology, University of Iowa, Iowa City, IA, USA.
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12
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Jacobs RQ, Carter ZI, Lucius AL, Schneider DA. Uncovering the mechanisms of transcription elongation by eukaryotic RNA polymerases I, II, and III. iScience 2022; 25:105306. [PMID: 36304104 PMCID: PMC9593817 DOI: 10.1016/j.isci.2022.105306] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Revised: 08/16/2022] [Accepted: 10/03/2022] [Indexed: 11/01/2022] Open
Abstract
Eukaryotes express three nuclear RNA polymerases (Pols I, II, and III) that are essential for cell survival. Despite extensive investigation of the three Pols, significant knowledge gaps regarding their biochemical properties remain because each Pol has been evaluated independently under disparate experimental conditions and methodologies. To advance our understanding of the Pols, we employed identical in vitro transcription assays for direct comparison of their elongation rates, elongation complex (EC) stabilities, and fidelities. Pol I is the fastest, most likely to misincorporate, forms the least stable EC, and is most sensitive to alterations in reaction buffers. Pol II is the slowest of the Pols, forms the most stable EC, and negligibly misincorporated an incorrect nucleotide. The enzymatic properties of Pol III were intermediate between Pols I and II in all assays examined. These results reveal unique enzymatic characteristics of the Pols that provide new insights into their evolutionary divergence.
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Affiliation(s)
- Ruth Q. Jacobs
- Department of Biochemistry and Molecular Genetics, School of Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Zachariah I. Carter
- Department of Chemistry, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Aaron L. Lucius
- Department of Chemistry, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - David A. Schneider
- Department of Biochemistry and Molecular Genetics, School of Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA
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13
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Marshall CJ, Qayyum MZ, Walker JE, Murakami KS, Santangelo TJ. The structure and activities of the archaeal transcription termination factor Eta detail vulnerabilities of the transcription elongation complex. Proc Natl Acad Sci U S A 2022; 119:e2207581119. [PMID: 35917344 PMCID: PMC9371683 DOI: 10.1073/pnas.2207581119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Accepted: 06/22/2022] [Indexed: 02/04/2023] Open
Abstract
Transcription must be properly regulated to ensure dynamic gene expression underlying growth, development, and response to environmental cues. Regulation is imposed throughout the transcription cycle, and while many efforts have detailed the regulation of transcription initiation and early elongation, the termination phase of transcription also plays critical roles in regulating gene expression. Transcription termination can be driven by only a few proteins in each domain of life. Detailing the mechanism(s) employed provides insight into the vulnerabilities of transcription elongation complexes (TECs) that permit regulated termination to control expression of many genes and operons. Here, we describe the biochemical activities and crystal structure of the superfamily 2 helicase Eta, one of two known factors capable of disrupting archaeal transcription elongation complexes. Eta retains a twin-translocase core domain common to all superfamily 2 helicases and a well-conserved C terminus wherein individual amino acid substitutions can critically abrogate termination activities. Eta variants that perturb ATPase, helicase, single-stranded DNA and double-stranded DNA translocase and termination activities identify key regions of the C terminus of Eta that, when combined with modeling Eta-TEC interactions, provide a structural model of Eta-mediated termination guided in part by structures of Mfd and the bacterial TEC. The susceptibility of TECs to disruption by termination factors that target the upstream surface of RNA polymerase and potentially drive termination through forward translocation and allosteric mechanisms that favor opening of the clamp to release the encapsulated nucleic acids emerges as a common feature of transcription termination mechanisms.
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Affiliation(s)
- Craig J. Marshall
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO 80523
| | - M. Zuhaib Qayyum
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA 16802
| | - Julie E. Walker
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO 80523
| | - Katsuhiko S. Murakami
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA 16802
| | - Thomas J. Santangelo
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO 80523
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14
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Xie J, Aiello U, Clement Y, Haidara N, Girbig M, Schmitzova J, Pena V, Müller CW, Libri D, Porrua O. An integrated model for termination of RNA polymerase III transcription. SCIENCE ADVANCES 2022; 8:eabm9875. [PMID: 35857496 PMCID: PMC9278858 DOI: 10.1126/sciadv.abm9875] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
RNA polymerase III (RNAPIII) synthesizes essential and abundant noncoding RNAs such as transfer RNAs. Controlling RNAPIII span of activity by accurate and efficient termination is a challenging necessity to ensure robust gene expression and to prevent conflicts with other DNA-associated machineries. The mechanism of RNAPIII termination is believed to be simpler than that of other eukaryotic RNA polymerases, solely relying on the recognition of a T-tract in the nontemplate strand. Here, we combine high-resolution genome-wide analyses and in vitro transcription termination assays to revisit the mechanism of RNAPIII transcription termination in budding yeast. We show that T-tracts are necessary but not always sufficient for termination and that secondary structures of the nascent RNAs are important auxiliary cis-acting elements. Moreover, we show that the helicase Sen1 plays a key role in a fail-safe termination pathway. Our results provide a comprehensive model illustrating how multiple mechanisms cooperate to ensure efficient RNAPIII transcription termination.
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Affiliation(s)
- Juanjuan Xie
- Université Paris Cité, CNRS, Institut Jacques Monod, F-75013 Paris, France
| | - Umberto Aiello
- Université Paris Cité, CNRS, Institut Jacques Monod, F-75013 Paris, France
| | - Yves Clement
- Université Paris Cité, CNRS, Institut Jacques Monod, F-75013 Paris, France
| | - Nouhou Haidara
- Université Paris Cité, CNRS, Institut Jacques Monod, F-75013 Paris, France
| | - Mathias Girbig
- European Molecular Biology Laboratory (EMBL), Structural and Computational Biology Unit, 69117 Heidelberg, Germany
- Joint PhD degree from EMBL and Heidelberg University, Faculty of Biosciences, Heidelberg, Germany
| | - Jana Schmitzova
- Max Planck Institute for Biophysical Chemistry, Macromolecular Crystallography, Am Fassberg 11, 37077 Goettingen, Germany
| | - Vladimir Pena
- Max Planck Institute for Biophysical Chemistry, Macromolecular Crystallography, Am Fassberg 11, 37077 Goettingen, Germany
| | - Christoph W. Müller
- European Molecular Biology Laboratory (EMBL), Structural and Computational Biology Unit, 69117 Heidelberg, Germany
| | - Domenico Libri
- Université Paris Cité, CNRS, Institut Jacques Monod, F-75013 Paris, France
- Corresponding author. (D.L.); (O.P.)
| | - Odil Porrua
- Université Paris Cité, CNRS, Institut Jacques Monod, F-75013 Paris, France
- Corresponding author. (D.L.); (O.P.)
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15
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Ball CB, Parida M, Li M, Spector BM, Suarez GA, Meier JL, Price DH. Human Cytomegalovirus Infection Elicits Global Changes in Host Transcription by RNA Polymerases I, II, and III. Viruses 2022; 14:v14040779. [PMID: 35458509 PMCID: PMC9026722 DOI: 10.3390/v14040779] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Revised: 03/29/2022] [Accepted: 03/30/2022] [Indexed: 12/29/2022] Open
Abstract
How human cytomegalovirus (HCMV) infection impacts the transcription of the host genome remains incompletely understood. Here, we examine the global consequences of infection of primary human foreskin fibroblasts (HFFs) on transcription by RNA polymerase I, II, and III over the course of a lytic infection using PRO-Seq. The expected rapid induction of innate immune response genes is observed with specific subsets of genes exhibiting dissimilar expression kinetics. We find minimal effects on Pol II initiation, but increased rates of the release of paused Pol II into productive elongation are detected by 24 h postinfection and pronounced at late times postinfection. Pol I transcription increases during infection and we provide evidence for a potential Pol I elongation control mechanism. Pol III transcription of tRNA genes is dramatically altered, with many induced and some repressed. All effects are partially dependent on viral genome replication, suggesting a link to viral mRNA levels and/or a viral early–late or late gene product. Changes in tRNA transcription are connected to distinct alterations in the chromatin state around tRNA genes, which were probed with high-resolution DFF-ChIP. Additionally, evidence is provided that the Pol III PIC stably contacts an upstream −1 nucleosome. Finally, we compared and contrasted our HCMV data with results from published experiments with HSV-1, EBV, KSHV, and MHV68. We report disparate effects on Pol II transcription and potentially similar effects on Pol III transcription.
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Affiliation(s)
- Christopher B. Ball
- Department of Biochemistry and Molecular Biology, University of Iowa, Iowa City, IA 52242, USA; (C.B.B.); (M.P.); (B.M.S.); (G.A.S.)
| | - Mrutyunjaya Parida
- Department of Biochemistry and Molecular Biology, University of Iowa, Iowa City, IA 52242, USA; (C.B.B.); (M.P.); (B.M.S.); (G.A.S.)
| | - Ming Li
- Departments of Internal Medicine and Epidemiology, University of Iowa and Iowa City Veterans Affairs Health Care System, Iowa City, IA 52242, USA; (M.L.); (J.L.M.)
| | - Benjamin M. Spector
- Department of Biochemistry and Molecular Biology, University of Iowa, Iowa City, IA 52242, USA; (C.B.B.); (M.P.); (B.M.S.); (G.A.S.)
| | - Gustavo A. Suarez
- Department of Biochemistry and Molecular Biology, University of Iowa, Iowa City, IA 52242, USA; (C.B.B.); (M.P.); (B.M.S.); (G.A.S.)
| | - Jeffery L. Meier
- Departments of Internal Medicine and Epidemiology, University of Iowa and Iowa City Veterans Affairs Health Care System, Iowa City, IA 52242, USA; (M.L.); (J.L.M.)
| | - David H. Price
- Department of Biochemistry and Molecular Biology, University of Iowa, Iowa City, IA 52242, USA; (C.B.B.); (M.P.); (B.M.S.); (G.A.S.)
- Correspondence:
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16
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Merkl PE, Schächner C, Pilsl M, Schwank K, Schmid C, Längst G, Milkereit P, Griesenbeck J, Tschochner H. Specialization of RNA Polymerase I in Comparison to Other Nuclear RNA Polymerases of Saccharomyces cerevisiae. Methods Mol Biol 2022; 2533:63-70. [PMID: 35796982 PMCID: PMC9761553 DOI: 10.1007/978-1-0716-2501-9_4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
In archaea and bacteria the major classes of RNAs are synthesized by one DNA-dependent RNA polymerase (RNAP). In contrast, most eukaryotes have three highly specialized RNAPs to transcribe the nuclear genome. RNAP I synthesizes almost exclusively ribosomal (r)RNA, RNAP II synthesizes mRNA as well as many noncoding RNAs involved in RNA processing or RNA silencing pathways and RNAP III synthesizes mainly tRNA and 5S rRNA. This review discusses functional differences of the three nuclear core RNAPs in the yeast S. cerevisiae with a particular focus on RNAP I transcription of nucleolar ribosomal (r)DNA chromatin.
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Affiliation(s)
- Philipp E Merkl
- Universität Regensburg, Regensburg Center for Biochemistry (RCB), Lehrstuhl Biochemie III, Regensburg, Germany
- TUM ForTe, Technische Universität München, Munich, Germany
| | - Christopher Schächner
- Universität Regensburg, Regensburg Center for Biochemistry (RCB), Lehrstuhl Biochemie III, Regensburg, Germany
| | - Michael Pilsl
- Universität Regensburg, Regensburg Center for Biochemistry (RCB), Lehrstuhl Biochemie III, Regensburg, Germany
| | - Katrin Schwank
- Universität Regensburg, Regensburg Center for Biochemistry (RCB), Lehrstuhl Biochemie III, Regensburg, Germany
| | - Catharina Schmid
- Universität Regensburg, Regensburg Center for Biochemistry (RCB), Lehrstuhl Biochemie III, Regensburg, Germany
| | - Gernot Längst
- Universität Regensburg, Regensburg Center for Biochemistry (RCB), Lehrstuhl Biochemie III, Regensburg, Germany
| | - Philipp Milkereit
- Universität Regensburg, Regensburg Center for Biochemistry (RCB), Lehrstuhl Biochemie III, Regensburg, Germany.
| | - Joachim Griesenbeck
- Universität Regensburg, Regensburg Center for Biochemistry (RCB), Lehrstuhl Biochemie III, Regensburg, Germany
| | - Herbert Tschochner
- Universität Regensburg, Regensburg Center for Biochemistry (RCB), Lehrstuhl Biochemie III, Regensburg, Germany.
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17
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Hou H, Li Y, Wang M, Liu A, Yu Z, Chen K, Zhao D, Xu Y. Structural insights into RNA polymerase III-mediated transcription termination through trapping poly-deoxythymidine. Nat Commun 2021; 12:6135. [PMID: 34675218 PMCID: PMC8531034 DOI: 10.1038/s41467-021-26402-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Accepted: 09/24/2021] [Indexed: 01/11/2023] Open
Abstract
Termination of the RNA polymerase III (Pol III)-mediated transcription requires the conversion of an elongation complex (EC) to a pre-termination complex (PTC) on poly-deoxythymidine (dT)-containing non-template strand, a mechanism distinct from Pol I and Pol II. Here, our in vitro transcription elongation assay showed that 5-7 dT-containing DNA template led to transcription termination of Pol III, but not Pol I or Pol II. We assembled human Pol III PTC on a 7 dT-containing DNA template and determined the structure at 3.6 Å resolution. The structure reveals that poly-dT are trapped in a narrow exit tunnel formed by RPC2. A hydrophobic gate of the exit tunnel separates the bases of two connected deoxythymidines and may prevent translocation of the non-template strand. The fork loop 2 stabilizes both template and non-template strands around the transcription fork, and may further prevent strand translocation. Our study shows that the Pol III-specific exit tunnel and FL2 allow for efficient translocation of non-poly-dT sequence during transcription elongation but trap poly-dT to promote DNA retention of Pol III, revealing molecular mechanism of poly-dT-dependent transcription termination of Pol III.
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Affiliation(s)
- Haifeng Hou
- Fudan University Shanghai Cancer Center, Institutes of Biomedical Sciences, State Key Laboratory of Genetic Engineering, Shanghai Key Laboratory of Radiation Oncology, and Shanghai Key Laboratory of Medical Epigenetics, Shanghai Medical College of Fudan University, Shanghai, 200032, China
| | - Yan Li
- Fudan University Shanghai Cancer Center, Institutes of Biomedical Sciences, State Key Laboratory of Genetic Engineering, Shanghai Key Laboratory of Radiation Oncology, and Shanghai Key Laboratory of Medical Epigenetics, Shanghai Medical College of Fudan University, Shanghai, 200032, China
| | - Mo Wang
- Fudan University Shanghai Cancer Center, Institutes of Biomedical Sciences, State Key Laboratory of Genetic Engineering, Shanghai Key Laboratory of Radiation Oncology, and Shanghai Key Laboratory of Medical Epigenetics, Shanghai Medical College of Fudan University, Shanghai, 200032, China
| | - Aijun Liu
- Fudan University Shanghai Cancer Center, Institutes of Biomedical Sciences, State Key Laboratory of Genetic Engineering, Shanghai Key Laboratory of Radiation Oncology, and Shanghai Key Laboratory of Medical Epigenetics, Shanghai Medical College of Fudan University, Shanghai, 200032, China
| | - Zishuo Yu
- Fudan University Shanghai Cancer Center, Institutes of Biomedical Sciences, State Key Laboratory of Genetic Engineering, Shanghai Key Laboratory of Radiation Oncology, and Shanghai Key Laboratory of Medical Epigenetics, Shanghai Medical College of Fudan University, Shanghai, 200032, China
| | - Ke Chen
- Fudan University Shanghai Cancer Center, Institutes of Biomedical Sciences, State Key Laboratory of Genetic Engineering, Shanghai Key Laboratory of Radiation Oncology, and Shanghai Key Laboratory of Medical Epigenetics, Shanghai Medical College of Fudan University, Shanghai, 200032, China
| | - Dan Zhao
- Fudan University Shanghai Cancer Center, Institutes of Biomedical Sciences, State Key Laboratory of Genetic Engineering, Shanghai Key Laboratory of Radiation Oncology, and Shanghai Key Laboratory of Medical Epigenetics, Shanghai Medical College of Fudan University, Shanghai, 200032, China
| | - Yanhui Xu
- Fudan University Shanghai Cancer Center, Institutes of Biomedical Sciences, State Key Laboratory of Genetic Engineering, Shanghai Key Laboratory of Radiation Oncology, and Shanghai Key Laboratory of Medical Epigenetics, Shanghai Medical College of Fudan University, Shanghai, 200032, China.
- The International Co-laboratory of Medical Epigenetics and Metabolism, Ministry of Science and Technology, China, Department of Systems Biology for Medicine, School of Basic Medical Sciences, Shanghai Medical College of Fudan University, Shanghai, 200032, China.
- Human Phenome Institute, Collaborative Innovation Center of Genetics and Development, School of Life Sciences, Fudan University, Shanghai, 200433, China.
- State Key Laboratory of Reproductive Regulation and Breeding of Grassland Livestock School of Life Sciences, Inner Mongolia University, Hohhot, 010070, P. R. China.
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18
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Abdelrahman M, Wei Z, Rohila JS, Zhao K. Multiplex Genome-Editing Technologies for Revolutionizing Plant Biology and Crop Improvement. FRONTIERS IN PLANT SCIENCE 2021; 12:721203. [PMID: 34691102 PMCID: PMC8526792 DOI: 10.3389/fpls.2021.721203] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2021] [Accepted: 09/01/2021] [Indexed: 05/26/2023]
Abstract
Multiplex genome-editing (MGE) technologies are recently developed versatile bioengineering tools for modifying two or more specific DNA loci in a genome with high precision. These genome-editing tools have greatly increased the feasibility of introducing desired changes at multiple nucleotide levels into a target genome. In particular, clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein (Cas) [CRISPR/Cas] system-based MGE tools allow the simultaneous generation of direct mutations precisely at multiple loci in a gene or multiple genes. MGE is enhancing the field of plant molecular biology and providing capabilities for revolutionizing modern crop-breeding methods as it was virtually impossible to edit genomes so precisely at the single base-pair level with prior genome-editing tools, such as zinc-finger nucleases (ZFNs) and transcription activator-like effector nucleases (TALENs). Recently, researchers have not only started using MGE tools to advance genome-editing applications in certain plant science fields but also have attempted to decipher and answer basic questions related to plant biology. In this review, we discuss the current progress that has been made toward the development and utilization of MGE tools with an emphasis on the improvements in plant biology after the discovery of CRISPR/Cas9. Furthermore, the most recent advancements involving CRISPR/Cas applications for editing multiple loci or genes are described. Finally, insights into the strengths and importance of MGE technology in advancing crop-improvement programs are presented.
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Affiliation(s)
- Mohamed Abdelrahman
- National Key Facility for Crop Gene Resources and Genetic Improvement, Institute of Crop Science, Chinese Academy of Agricultural Sciences, Beijing, China
- Rice Research and Training Center, Field Crops Research Institute, Agricultural Research Center, Kafr El-Shaikh, Egypt
| | - Zheng Wei
- National Key Facility for Crop Gene Resources and Genetic Improvement, Institute of Crop Science, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Jai S. Rohila
- Dale Bumpers National Rice Research Center, United States Department of Agriculture - Agricultural Research Services, Stuttgart, AR, United States
| | - Kaijun Zhao
- National Key Facility for Crop Gene Resources and Genetic Improvement, Institute of Crop Science, Chinese Academy of Agricultural Sciences, Beijing, China
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19
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Analysis of SINE Families B2, Dip, and Ves with Special Reference to Polyadenylation Signals and Transcription Terminators. Int J Mol Sci 2021; 22:ijms22189897. [PMID: 34576060 PMCID: PMC8466645 DOI: 10.3390/ijms22189897] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Revised: 09/05/2021] [Accepted: 09/06/2021] [Indexed: 01/09/2023] Open
Abstract
Short Interspersed Elements (SINEs) are eukaryotic non-autonomous retrotransposons transcribed by RNA polymerase III (pol III). The 3′-terminus of many mammalian SINEs has a polyadenylation signal (AATAAA), pol III transcription terminator, and A-rich tail. The RNAs of such SINEs can be polyadenylated, which is unique for pol III transcripts. Here, B2 (mice and related rodents), Dip (jerboas), and Ves (vespertilionid bats) SINE families were thoroughly studied. They were divided into subfamilies reliably distinguished by relatively long indels. The age of SINE subfamilies can be estimated, which allows us to reconstruct their evolution. The youngest and most active variants of SINE subfamilies were given special attention. The shortest pol III transcription terminators are TCTTT (B2), TATTT (Ves and Dip), and the rarer TTTT. The last nucleotide of the terminator is often not transcribed; accordingly, the truncated terminator of its descendant becomes nonfunctional. The incidence of complete transcription of the TCTTT terminator is twice higher compared to TTTT and thus functional terminators are more likely preserved in daughter SINE copies. Young copies have long poly(A) tails; however, they gradually shorten in host generations. Unexpectedly, the tail shortening below A10 increases the incidence of terminator elongation by Ts thus restoring its efficiency. This process can be critical for the maintenance of SINE activity in the genome.
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20
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Moreb EA, Lynch MD. Genome dependent Cas9/gRNA search time underlies sequence dependent gRNA activity. Nat Commun 2021; 12:5034. [PMID: 34413309 PMCID: PMC8377084 DOI: 10.1038/s41467-021-25339-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Accepted: 08/04/2021] [Indexed: 02/08/2023] Open
Abstract
CRISPR-Cas9 is a powerful DNA editing tool. A gRNA directs Cas9 to cleave any DNA sequence with a PAM. However, some gRNA sequences mediate cleavage at higher efficiencies than others. To understand this, numerous studies have screened large gRNA libraries and developed algorithms to predict gRNA sequence dependent activity. These algorithms do not predict other datasets as well as their training dataset and do not predict well between species. Here, to better understand these discrepancies, we retrospectively examine sequence features that impact gRNA activity in 44 published data sets. We find strong evidence that gRNA sequence dependent activity is largely influenced by the ability of the Cas9/gRNA complex to find the target site rather than activity at the target site and that this drives sequence dependent differences in gRNA activity between different species. This understanding will help guide future work to understand Cas9 activity as well as efforts to identify optimal gRNAs and improve Cas9 variants.
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Affiliation(s)
- E A Moreb
- Department of Biomedical Engineering, Duke University, Durham, USA
| | - M D Lynch
- Department of Biomedical Engineering, Duke University, Durham, USA.
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21
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Structure of human RNA polymerase III elongation complex. Cell Res 2021; 31:791-800. [PMID: 33674783 PMCID: PMC8249397 DOI: 10.1038/s41422-021-00472-2] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Accepted: 01/06/2021] [Indexed: 01/31/2023] Open
Abstract
RNA polymerase III (Pol III) transcribes essential structured small RNAs, such as tRNAs, 5S rRNA and U6 snRNA. The transcriptional activity of Pol III is tightly controlled and its dysregulation is associated with human diseases, such as cancer. Human Pol III has two isoforms with difference only in one of its subunits RPC7 (α and β). Despite structural studies of yeast Pol III, structure of human Pol III remains unsolved. Here, we determined the structures of 17-subunit human Pol IIIα complex in the backtracked and post-translocation states, respectively. Human Pol III contains a generally conserved catalytic core, similar to that of yeast counterpart, and structurally unique RPC3-RPC6-RPC7 heterotrimer and RPC10. The N-ribbon of TFIIS-like RPC10 docks on the RPC4-RPC5 heterodimer and the C-ribbon inserts into the funnel of Pol III in the backtracked state but is more flexible in the post-translocation state. RPC7 threads through the heterotrimer and bridges the stalk and Pol III core module. The winged helix 1 domain of RPC6 and the N-terminal region of RPC7α stabilize each other and may prevent Maf1-mediated repression of Pol III activity. The C-terminal FeS cluster of RPC6 coordinates a network of interactions that mediate core-heterotrimer contacts and stabilize Pol III. Our structural analysis sheds new light on the molecular mechanism of human Pol IIIα-specific transcriptional regulation and provides explanations for upregulated Pol III activity in RPC7α-dominant cancer cells.
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22
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Tálas A, Huszár K, Kulcsár PI, Varga JK, Varga É, Tóth E, Welker Z, Erdős G, Pach PF, Welker Á, Györgypál Z, Tusnády GE, Welker E. A method for characterizing Cas9 variants via a one-million target sequence library of self-targeting sgRNAs. Nucleic Acids Res 2021; 49:e31. [PMID: 33450024 PMCID: PMC8034649 DOI: 10.1093/nar/gkaa1220] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Revised: 11/16/2020] [Accepted: 01/06/2021] [Indexed: 12/26/2022] Open
Abstract
Detailed target-selectivity information and experiment-based efficacy prediction tools are primarily available for Streptococcus pyogenes Cas9 (SpCas9). One obstacle to develop such tools is the rarity of accurate data. Here, we report a method termed ‘Self-targeting sgRNA Library Screen’ (SLS) for assaying the activity of Cas9 nucleases in bacteria using random target/sgRNA libraries of self-targeting sgRNAs. Exploiting more than a million different sequences, we demonstrate the use of the method with the SpCas9-HF1 variant to analyse its activity and reveal motifs that influence its target-selectivity. We have also developed an algorithm for predicting the activity of SpCas9-HF1 with an accuracy matching those of existing tools. SLS is a facile alternative to the much more expensive and laborious approaches used currently and has the capability of delivering sufficient amount of data for most of the orthologs and variants of SpCas9.
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Affiliation(s)
- András Tálas
- Institute of Enzymology, Research Centre for Natural Sciences, Budapest, Hungary.,School of Ph.D. Studies, Semmelweis University, Budapest, Hungary
| | - Krisztina Huszár
- Institute of Enzymology, Research Centre for Natural Sciences, Budapest, Hungary.,Gene Design Ltd, Szeged, Hungary
| | - Péter István Kulcsár
- Institute of Enzymology, Research Centre for Natural Sciences, Budapest, Hungary.,Biospiral-2006 Ltd, Szeged, Hungary.,School of Ph.D. Studies, University of Szeged, Hungary
| | - Julia K Varga
- Institute of Enzymology, Research Centre for Natural Sciences, Budapest, Hungary
| | - Éva Varga
- Institute of Enzymology, Research Centre for Natural Sciences, Budapest, Hungary.,School of Ph.D. Studies, University of Szeged, Hungary.,Institute of Biochemistry, Biological Research Centre, Szeged, Hungary
| | - Eszter Tóth
- Institute of Enzymology, Research Centre for Natural Sciences, Budapest, Hungary
| | | | | | | | - Ágnes Welker
- Institute of Enzymology, Research Centre for Natural Sciences, Budapest, Hungary
| | - Zoltán Györgypál
- Institute of Biophysics, Biological Research Centre, Szeged, Hungary
| | - Gábor E Tusnády
- Institute of Enzymology, Research Centre for Natural Sciences, Budapest, Hungary
| | - Ervin Welker
- Institute of Enzymology, Research Centre for Natural Sciences, Budapest, Hungary.,Institute of Biochemistry, Biological Research Centre, Szeged, Hungary
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23
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Verosloff MS, Corcoran WK, Dolberg TB, Bushhouse DZ, Leonard JN, Lucks JB. RNA Sequence and Structure Determinants of Pol III Transcriptional Termination in Human Cells. J Mol Biol 2021; 433:166978. [PMID: 33811918 DOI: 10.1016/j.jmb.2021.166978] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Revised: 03/23/2021] [Accepted: 03/24/2021] [Indexed: 01/25/2023]
Abstract
The precise mechanism of transcription termination of the eukaryotic RNA polymerase III (Pol III) has been a subject of considerable debate. Although previous studies have clearly shown that multiple uracils at the end of RNA transcripts are required for Pol III termination, the effects of upstream RNA secondary structure in the nascent transcript on transcriptional termination is still unclear. To address this, we developed an in cellulo Pol III transcription termination assay using the recently developed Tornado-Corn RNA aptamer system to create a Pol III-transcribed RNA that produces a detectable fluorescent signal when transcribed in human cells. To study the effects of RNA sequence and structure on Pol III termination, we systematically varied the sequence context upstream of the aptamer and identified sequence characteristics that enhance or diminish termination. For transcription from Pol III type 3 promoters, we found that only poly-U tracts longer than the average length found in the human genome efficiently terminate Pol III transcription without RNA secondary structure elements. We observed that RNA secondary structure elements placed in proximity to shorter poly-U tracts induced termination, and RNA secondary structure by itself was not sufficient to induce termination. For Pol III type 2 promoters, we found that the shorter poly-U tract lengths of 4 uracils were sufficient to induce termination. These findings demonstrate a key role for sequence and structural elements within Pol III-transcribed nascent RNA for efficient transcription termination, and demonstrate a generalizable assay for characterizing Pol III transcription in human cells.
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Affiliation(s)
- Matthew S Verosloff
- Interdisciplinary Biological Sciences Graduate Program, Northwestern University, 2204 Tech Drive, Evanston, IL 60208, USA; Center for Synthetic Biology, Northwestern University, 2145 Sheridan Rd, Evanston, IL 60208, USA
| | - William K Corcoran
- Interdisciplinary Biological Sciences Graduate Program, Northwestern University, 2204 Tech Drive, Evanston, IL 60208, USA; Center for Synthetic Biology, Northwestern University, 2145 Sheridan Rd, Evanston, IL 60208, USA
| | - Taylor B Dolberg
- Center for Synthetic Biology, Northwestern University, 2145 Sheridan Rd, Evanston, IL 60208, USA; Department of Chemical and Biological Engineering, Northwestern University, 2145 Sheridan Rd, Evanston, IL 60208, USA
| | - David Z Bushhouse
- Interdisciplinary Biological Sciences Graduate Program, Northwestern University, 2204 Tech Drive, Evanston, IL 60208, USA; Center for Synthetic Biology, Northwestern University, 2145 Sheridan Rd, Evanston, IL 60208, USA
| | - Joshua N Leonard
- Center for Synthetic Biology, Northwestern University, 2145 Sheridan Rd, Evanston, IL 60208, USA; Department of Chemical and Biological Engineering, Northwestern University, 2145 Sheridan Rd, Evanston, IL 60208, USA.
| | - Julius B Lucks
- Center for Synthetic Biology, Northwestern University, 2145 Sheridan Rd, Evanston, IL 60208, USA; Department of Chemical and Biological Engineering, Northwestern University, 2145 Sheridan Rd, Evanston, IL 60208, USA.
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24
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Spt4 Promotes Pol I Processivity and Transcription Elongation. Genes (Basel) 2021; 12:genes12030413. [PMID: 33809333 PMCID: PMC8000598 DOI: 10.3390/genes12030413] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Revised: 03/03/2021] [Accepted: 03/09/2021] [Indexed: 01/25/2023] Open
Abstract
RNA polymerases (Pols) I, II, and III collectively synthesize most of the RNA in a eukaryotic cell. Transcription by Pols I, II, and III is regulated by hundreds of trans-acting factors. One such protein, Spt4, has been previously identified as a transcription factor that influences both Pols I and II. Spt4 forms a complex with Spt5, described as the Spt4/5 complex (or DSIF in mammalian cells). This complex has been shown previously to directly interact with Pol I and potentially affect transcription elongation. The previous literature identified defects in transcription by Pol I when SPT4 was deleted, but the necessary tools to characterize the mechanism of this effect were not available at the time. Here, we use a technique called Native Elongating Transcript Sequencing (NET-seq) to probe for the global occupancy of Pol I in wild-type (WT) and spt4△ Saccharomyces cerevisiae (yeast) cells at single nucleotide resolution in vivo. Analysis of NET-seq data reveals that Spt4 promotes Pol I processivity and enhances transcription elongation through regions of the ribosomal DNA that are particularly G-rich. These data suggest that Spt4/5 may directly affect transcription elongation by Pol I in vivo.
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25
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Bousquet L, Hemon C, Malburet P, Bucchini F, Vandepoele K, Grimsley N, Moreau H, Echeverria M. The medium-size noncoding RNA transcriptome of Ostreococcus tauri, the smallest living eukaryote, reveals a large family of small nucleolar RNAs displaying multiple genomic expression strategies. NAR Genom Bioinform 2020; 2:lqaa080. [PMID: 33575626 PMCID: PMC7671301 DOI: 10.1093/nargab/lqaa080] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Revised: 08/31/2020] [Accepted: 09/17/2020] [Indexed: 11/14/2022] Open
Abstract
The small nucleolar RNAs (snoRNAs), essential for ribosome biogenesis, constitute a major family of medium-size noncoding RNAs (mncRNAs) in all eukaryotes. We present here, for the first time in a marine unicellular alga, the characterization of the snoRNAs family in Ostreococcus tauri, the smallest photosynthetic eukaryote. Using a transcriptomic approach, we identified 131 O. tauri snoRNAs (Ot–snoRNA) distributed in three classes: the C/D snoRNAs, the H/ACA snoRNAs and the MRP RNA. Their genomic organization revealed a unique combination of both the intronic organization of animals and the polycistronic organization of plants. Remarkably, clustered genes produced Ot–snoRNAs with unusual structures never previously described in plants. Their abundances, based on quantification of reads and northern blots, showed extreme differences in Ot–snoRNA accumulation, mainly determined by their differential stability. Most of these Ot–snoRNAs were predicted to target rRNAs or snRNAs. Seventeen others were orphan Ot–snoRNAs that would not target rRNA. These were specific to O. tauri or Mamiellophyceae and could have functions unrelated to ribosome biogenesis. Overall, these data reveal an ‘evolutionary response’ adapted to the extreme compactness of the O. tauri genome that accommodates the essential Ot–snoRNAs, developing multiple strategies to optimize their coordinated expression with a minimal cost on regulatory circuits.
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Affiliation(s)
- Laurie Bousquet
- Sorbonne Université, CNRS, Laboratoire de Biologie Intégrative des Organismes Marins , UMR7232, F-66650 Banyuls sur Mer, France
| | - Claire Hemon
- Sorbonne Université, CNRS, Laboratoire de Biologie Intégrative des Organismes Marins , UMR7232, F-66650 Banyuls sur Mer, France
| | - Paul Malburet
- Sorbonne Université, CNRS, Laboratoire de Biologie Intégrative des Organismes Marins , UMR7232, F-66650 Banyuls sur Mer, France
| | - François Bucchini
- Department of Plant Systems Biology,VIB, 9052 Ghent, Belgium
- Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Ghent, Belgium
| | - Klaas Vandepoele
- Department of Plant Systems Biology,VIB, 9052 Ghent, Belgium
- Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Ghent, Belgium
- Bioinformatic Institute Ghent, Ghent University, 9052 Ghent, Belgium
| | - Nigel Grimsley
- Sorbonne Université, CNRS, Laboratoire de Biologie Intégrative des Organismes Marins , UMR7232, F-66650 Banyuls sur Mer, France
| | - Hervé Moreau
- Sorbonne Université, CNRS, Laboratoire de Biologie Intégrative des Organismes Marins , UMR7232, F-66650 Banyuls sur Mer, France
| | - Manuel Echeverria
- Sorbonne Université, CNRS, Laboratoire de Biologie Intégrative des Organismes Marins , UMR7232, F-66650 Banyuls sur Mer, France
- Département de Biologie, Université de Perpignan via Domitia, 66860 Perpignan Cedex, France
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26
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Wenck BR, Santangelo TJ. Archaeal transcription. Transcription 2020; 11:199-210. [PMID: 33112729 PMCID: PMC7714419 DOI: 10.1080/21541264.2020.1838865] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Revised: 10/12/2020] [Accepted: 10/13/2020] [Indexed: 12/15/2022] Open
Abstract
Increasingly sophisticated biochemical and genetic techniques are unraveling the regulatory factors and mechanisms that control gene expression in the Archaea. While some similarities in regulatory strategies are universal, archaeal-specific regulatory strategies are emerging to complement a complex patchwork of shared archaeal-bacterial and archaeal-eukaryotic regulatory mechanisms employed in the archaeal domain. The prokaryotic archaea encode core transcription components with homology to the eukaryotic transcription apparatus and also share a simplified eukaryotic-like initiation mechanism, but also deploy tactics common to bacterial systems to regulate promoter usage and influence elongation-termination decisions. We review the recently established complete archaeal transcription cycle, highlight recent findings of the archaeal transcription community and detail the expanding post-initiation regulation imposed on archaeal transcription.
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Affiliation(s)
- Breanna R. Wenck
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO, USA
| | - Thomas J. Santangelo
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO, USA
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27
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Yang B, Schwartz M, McJunkin K. In vivo CRISPR screening for phenotypic targets of the mir-35-42 family in C. elegans. Genes Dev 2020; 34:1227-1238. [PMID: 32820039 PMCID: PMC7462058 DOI: 10.1101/gad.339333.120] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Accepted: 07/27/2020] [Indexed: 12/26/2022]
Abstract
In this study, Yang et al. devised a novel strategy to test the phenotypic impact of individual microRNA–target interactions by disrupting each predicted miRNA-binding site by CRISPR–Cas9 genome editing in C. elegans. They developed a multiplexed negative selection screening approach, in which edited loci are deep sequenced, and candidate sites are prioritized based on apparent selection pressure against mutations that disrupt miRNA binding. Identifying miRNA target genes is difficult, and delineating which targets are the most biologically important is even more difficult. We devised a novel strategy to test the phenotypic impact of individual microRNA–target interactions by disrupting each predicted miRNA-binding site by CRISPR–Cas9 genome editing in C. elegans. We developed a multiplexed negative selection screening approach in which edited loci are deep sequenced, and candidate sites are prioritized based on apparent selection pressure against mutations that disrupt miRNA binding. Importantly, our screen was conducted in vivo on mutant animals, allowing us to interrogate organism-level phenotypes. We used this approach to screen for phenotypic targets of the essential mir-35-42 family. By generating 1130 novel 3′UTR alleles across all predicted targets, we identified egl-1 as a phenotypic target whose derepression partially phenocopies the mir-35-42 mutant phenotype by inducing embryonic lethality and low fecundity. These phenotypes can be rescued by compensatory CRISPR mutations that retarget mir-35 to the mutant egl-1 3′UTR. This study demonstrates that the application of in vivo whole organismal CRISPR screening has great potential to accelerate the discovery of phenotypic negative regulatory elements in the noncoding genome.
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Affiliation(s)
- Bing Yang
- National Institute of Diabetes and Digestive and Kidney Diseases Intramural Research Program, National Institutes of Health, Bethesda, Maryland 20815, USA
| | - Matthew Schwartz
- Department of Biology, University of Utah, Salt Lake City, Utah 84112, USA
| | - Katherine McJunkin
- National Institute of Diabetes and Digestive and Kidney Diseases Intramural Research Program, National Institutes of Health, Bethesda, Maryland 20815, USA
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28
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CRISPR-Cas9 System for Plant Genome Editing: Current Approaches and Emerging Developments. AGRONOMY-BASEL 2020. [DOI: 10.3390/agronomy10071033] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Targeted genome editing using CRISPR-Cas9 has been widely adopted as a genetic engineering tool in various biological systems. This editing technology has been in the limelight due to its simplicity and versatility compared to other previously known genome editing platforms. Several modifications of this editing system have been established for adoption in a variety of plants, as well as for its improved efficiency and portability, bringing new opportunities for the development of transgene-free improved varieties of economically important crops. This review presents an overview of CRISPR-Cas9 and its application in plant genome editing. A catalog of the current and emerging approaches for the implementation of the system in plants is also presented with details on the existing gaps and limitations. Strategies for the establishment of the CRISPR-Cas9 molecular construct such as the selection of sgRNAs, PAM compatibility, choice of promoters, vector architecture, and multiplexing approaches are emphasized. Progress in the delivery and transgene detection methods, together with optimization approaches for improved on-target efficiency are also detailed in this review. The information laid out here will provide options useful for the effective and efficient exploitation of the system for plant genome editing and will serve as a baseline for further developments of the system. Future combinations and fine-tuning of the known parameters or factors that contribute to the editing efficiency, fidelity, and portability of CRISPR-Cas9 will indeed open avenues for new technological advancements of the system for targeted gene editing in plants.
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29
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Fueller J, Herbst K, Meurer M, Gubicza K, Kurtulmus B, Knopf JD, Kirrmaier D, Buchmuller BC, Pereira G, Lemberg MK, Knop M. CRISPR-Cas12a-assisted PCR tagging of mammalian genes. J Cell Biol 2020; 219:e201910210. [PMID: 32406907 PMCID: PMC7265327 DOI: 10.1083/jcb.201910210] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Revised: 02/10/2020] [Accepted: 03/26/2020] [Indexed: 12/20/2022] Open
Abstract
Here we describe a time-efficient strategy for endogenous C-terminal gene tagging in mammalian tissue culture cells. An online platform is used to design two long gene-specific oligonucleotides for PCR with generic template cassettes to create linear dsDNA donors, termed PCR cassettes. PCR cassettes encode the tag (e.g., GFP), a Cas12a CRISPR RNA for cleavage of the target locus, and short homology arms for directed integration via homologous recombination. The integrated tag is coupled to a generic terminator shielding the tagged gene from the co-inserted auxiliary sequences. Co-transfection of PCR cassettes with a Cas12a-encoding plasmid leads to robust endogenous expression of tagged genes, with tagging efficiency of up to 20% without selection, and up to 60% when selection markers are used. We used target-enrichment sequencing to investigate all potential sources of artifacts. Our work outlines a quick strategy particularly suitable for exploratory studies using endogenous expression of fluorescent protein-tagged genes.
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Affiliation(s)
- Julia Fueller
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), German Cancer Research Center (DKFZ)-ZMBH Alliance, Heidelberg, Germany
| | - Konrad Herbst
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), German Cancer Research Center (DKFZ)-ZMBH Alliance, Heidelberg, Germany
| | - Matthias Meurer
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), German Cancer Research Center (DKFZ)-ZMBH Alliance, Heidelberg, Germany
| | - Krisztina Gubicza
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), German Cancer Research Center (DKFZ)-ZMBH Alliance, Heidelberg, Germany
| | - Bahtiyar Kurtulmus
- Center for Organismal Studies, University of Heidelberg and DKFZ, DKFZ-ZMBH Alliance, Heidelberg, Germany
| | - Julia D. Knopf
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), German Cancer Research Center (DKFZ)-ZMBH Alliance, Heidelberg, Germany
| | - Daniel Kirrmaier
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), German Cancer Research Center (DKFZ)-ZMBH Alliance, Heidelberg, Germany
- Cell Morphogenesis and Signal Transduction, DKFZ-ZMBH Alliance and DKFZ, Heidelberg, Germany
| | - Benjamin C. Buchmuller
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), German Cancer Research Center (DKFZ)-ZMBH Alliance, Heidelberg, Germany
| | - Gislene Pereira
- Center for Organismal Studies, University of Heidelberg and DKFZ, DKFZ-ZMBH Alliance, Heidelberg, Germany
| | - Marius K. Lemberg
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), German Cancer Research Center (DKFZ)-ZMBH Alliance, Heidelberg, Germany
| | - Michael Knop
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), German Cancer Research Center (DKFZ)-ZMBH Alliance, Heidelberg, Germany
- Cell Morphogenesis and Signal Transduction, DKFZ-ZMBH Alliance and DKFZ, Heidelberg, Germany
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30
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Berkemer SJ, Maier LK, Amman F, Bernhart SH, Wörtz J, Märkle P, Pfeiffer F, Stadler PF, Marchfelder A. Identification of RNA 3´ ends and termination sites in Haloferax volcanii. RNA Biol 2020; 17:663-676. [PMID: 32041469 PMCID: PMC7237163 DOI: 10.1080/15476286.2020.1723328] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Archaeal genomes are densely packed; thus, correct transcription termination is an important factor for orchestrated gene expression. A systematic analysis of RNA 3´ termini, to identify transcription termination sites (TTS) using RNAseq data has hitherto only been performed in two archaea, Methanosarcina mazei and Sulfolobus acidocaldarius. In this study, only regions directly downstream of annotated genes were analysed, and thus, only part of the genome had been investigated. Here, we developed a novel algorithm (Internal Enrichment-Peak Calling) that allows an unbiased, genome-wide identification of RNA 3´ termini independent of annotation. In an RNA fraction enriched for primary transcripts by terminator exonuclease (TEX) treatment we identified 1,543 RNA 3´ termini. Approximately half of these were located in intergenic regions, and the remainder were found in coding regions. A strong sequence signature consistent with known termination events at intergenic loci indicates a clear enrichment for native TTS among them. Using these data we determined distinct putative termination motifs for intergenic (a T stretch) and coding regions (AGATC). In vivo reporter gene tests of selected TTS confirmed termination at these sites, which exemplify the different motifs. For several genes, more than one termination site was detected, resulting in transcripts with different lengths of the 3´ untranslated region (3´ UTR).
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Affiliation(s)
- Sarah J Berkemer
- Bioinformatics Group, Department of Computer Science - and Interdisciplinary Center for Bioinformatics, University of Leipzig, Leipzig, Germany.,Max Planck Institute for Mathematics in the Sciences, Leipzig, Germany
| | | | - Fabian Amman
- Institute for Theoretical Chemistry, University of Vienna, Vienna, Austria.,Division of Cell and Developmental Biology, Medical University Vienna, Vienna, Austria
| | - Stephan H Bernhart
- Bioinformatics Group, Department of Computer Science - and Interdisciplinary Center for Bioinformatics, University of Leipzig, Leipzig, Germany.,Transcriptome Bioinformatics, Interdisciplinary Center for Bioinformatics, Leipzig University, Leipzig, Germany
| | | | | | - Friedhelm Pfeiffer
- Computational Biology Group, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Peter F Stadler
- Bioinformatics Group, Department of Computer Science - and Interdisciplinary Center for Bioinformatics, University of Leipzig, Leipzig, Germany.,Max Planck Institute for Mathematics in the Sciences, Leipzig, Germany.,Institute for Theoretical Chemistry, University of Vienna, Vienna, Austria.,Facultad de Ciencias, Universidad Nacional de Colombia, Bogotá, Colombia.,Center for RNA in Technology and Health, University Copenhagen, Frederiksberg C, Denmark.,Santa Fe Institute, Santa Fe, NM, USA.,German Centre for Integrative Biodiversity Research (iDiv), Halle, Jena and Leipzig, Germany.,Competence Center for Scalable Data Services and Solutions, and Leipzig, Research Center for Civilization Diseases, University Leipzig, Leipzig, Germany
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31
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Simultaneous Measurement of Transcriptional and Post-transcriptional Parameters by 3' End RNA-Seq. Cell Rep 2020; 24:2468-2478.e4. [PMID: 30157438 PMCID: PMC6130049 DOI: 10.1016/j.celrep.2018.07.104] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2017] [Revised: 05/31/2018] [Accepted: 07/30/2018] [Indexed: 11/23/2022] Open
Abstract
Cellular RNA levels are determined by transcription and decay rates, which are fundamental in understanding gene expression regulation. Measurement of these two parameters is usually performed independently, complicating analysis as well as introducing methodological biases and batch effects that hamper direct comparison. Here, we present a simple approach of concurrent sequencing of S. cerevisiae poly(A)+ and poly(A)- RNA 3' ends to simultaneously estimate total RNA levels, transcription, and decay rates from the same RNA sample. The transcription data generated correlate well with reported estimates and also reveal local RNA polymerase stalling and termination sites with high precision. Although the method by design uses brief metabolic labeling of newly synthesized RNA with 4-thiouracil, the results demonstrate that transcription estimates can also be gained from unlabeled RNA samples. These findings underscore the potential of the approach, which should be generally applicable to study a range of biological questions in diverse organisms.
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32
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Xiong HB, Wang J, Huang C, Rochaix JD, Lin FM, Zhang JX, Ye LS, Shi XH, Yu QB, Yang ZN. mTERF8, a Member of the Mitochondrial Transcription Termination Factor Family, Is Involved in the Transcription Termination of Chloroplast Gene psbJ. PLANT PHYSIOLOGY 2020; 182:408-423. [PMID: 31685645 PMCID: PMC6945865 DOI: 10.1104/pp.19.00906] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Accepted: 10/21/2019] [Indexed: 05/28/2023]
Abstract
Members of the mitochondrial transcription terminator factor (mTERF) family, originally identified in vertebrate mitochondria, are involved in the termination of organellular transcription. In plants, mTERF proteins are mainly localized in chloroplasts and mitochondria. In Arabidopsis (Arabidopsis thaliana), mTERF8/pTAC15 was identified in the plastid-encoded RNA polymerase (PEP) complex, the major RNA polymerase of chloroplasts. In this work, we demonstrate that mTERF8 is associated with the PEP complex. An mTERF8 knockout line displayed a wild-type-like phenotype under standard growth conditions, but showed impaired efficiency of photosystem II electron flow. Transcription of most chloroplast genes was not substantially affected in the mterf8 mutant; however, the level of the psbJ transcript from the psbEFLJ polycistron was increased. RNA blot analysis showed that a larger transcript accumulates in mterf8 than in the wild type. Thus, abnormal transcription and/or RNA processing occur for the psbEFLJ polycistron. Circular reverse transcription PCR and sequence analysis showed that the psbJ transcript terminates 95 nucleotides downstream of the translation stop codon in the wild type, whereas its termination is aberrant in mterf8 Both electrophoresis mobility shift assays and chloroplast chromatin immunoprecipitation analysis showed that mTERF8 specifically binds to the 3' terminal region of psbJ Transcription analysis using the in vitro T7 RNA polymerase system showed that mTERF8 terminates psbJ transcription. Together, these results suggest that mTERF8 is specifically involved in the transcription termination of the chloroplast gene psbJ.
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Affiliation(s)
- Hai-Bo Xiong
- Shanghai Key Laboratory of Plant Molecular Sciences, College of Life Sciences, Shanghai Normal University, Shanghai 200234, China
| | - Jing Wang
- Shanghai Key Laboratory of Plant Molecular Sciences, College of Life Sciences, Shanghai Normal University, Shanghai 200234, China
| | - Chao Huang
- Hunan Provincial Key Laboratory of Phytohormones and Growth Development, Hunan Agricultural University, Changsha 410128, China
| | - Jean-David Rochaix
- Departments of Molecular Biology and Plant Biology, University of Geneva, 1211 Geneva, Switzerland
| | - Fei-Min Lin
- Shanghai Key Laboratory of Plant Molecular Sciences, College of Life Sciences, Shanghai Normal University, Shanghai 200234, China
| | - Jia-Xing Zhang
- Shanghai Key Laboratory of Plant Molecular Sciences, College of Life Sciences, Shanghai Normal University, Shanghai 200234, China
| | - Lin-Shan Ye
- Shanghai Key Laboratory of Plant Molecular Sciences, College of Life Sciences, Shanghai Normal University, Shanghai 200234, China
| | - Xiao-He Shi
- Shanghai Key Laboratory of Plant Molecular Sciences, College of Life Sciences, Shanghai Normal University, Shanghai 200234, China
| | - Qing-Bo Yu
- Shanghai Key Laboratory of Plant Molecular Sciences, College of Life Sciences, Shanghai Normal University, Shanghai 200234, China
| | - Zhong-Nan Yang
- Shanghai Key Laboratory of Plant Molecular Sciences, College of Life Sciences, Shanghai Normal University, Shanghai 200234, China
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33
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Thornlow BP, Armstrong J, Holmes AD, Howard JM, Corbett-Detig RB, Lowe TM. Predicting transfer RNA gene activity from sequence and genome context. Genome Res 2020; 30:85-94. [PMID: 31857444 PMCID: PMC6961574 DOI: 10.1101/gr.256164.119] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Accepted: 12/12/2019] [Indexed: 01/25/2023]
Abstract
Transfer RNA (tRNA) genes are among the most highly transcribed genes in the genome owing to their central role in protein synthesis. However, there is evidence for a broad range of gene expression across tRNA loci. This complexity, combined with difficulty in measuring transcript abundance and high sequence identity across transcripts, has severely limited our collective understanding of tRNA gene expression regulation and evolution. We establish sequence-based correlates to tRNA gene expression and develop a tRNA gene classification method that does not require, but benefits from, comparative genomic information and achieves accuracy comparable to molecular assays. We observe that guanine + cytosine (G + C) content and CpG density surrounding tRNA loci is exceptionally well correlated with tRNA gene activity, supporting a prominent regulatory role of the local genomic context in combination with internal sequence features. We use our tRNA gene activity predictions in conjunction with a comprehensive tRNA gene ortholog set spanning 29 placental mammals to estimate the evolutionary rate of functional changes among orthologs. Our method adds a new dimension to large-scale tRNA functional prediction and will help prioritize characterization of functional tRNA variants. Its simplicity and robustness should enable development of similar approaches for other clades, as well as exploration of functional diversification of members of large gene families.
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Affiliation(s)
- Bryan P Thornlow
- Department of Biomolecular Engineering, University of California, Santa Cruz, California 95064, USA
| | - Joel Armstrong
- Department of Biomolecular Engineering, University of California, Santa Cruz, California 95064, USA
- Genomics Institute, University of California, Santa Cruz, California 95064, USA
| | - Andrew D Holmes
- Department of Biomolecular Engineering, University of California, Santa Cruz, California 95064, USA
| | - Jonathan M Howard
- Department of Biomolecular Engineering, University of California, Santa Cruz, California 95064, USA
| | - Russell B Corbett-Detig
- Department of Biomolecular Engineering, University of California, Santa Cruz, California 95064, USA
- Genomics Institute, University of California, Santa Cruz, California 95064, USA
| | - Todd M Lowe
- Department of Biomolecular Engineering, University of California, Santa Cruz, California 95064, USA
- Genomics Institute, University of California, Santa Cruz, California 95064, USA
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34
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Rivosecchi J, Larochelle M, Teste C, Grenier F, Malapert A, Ricci EP, Bernard P, Bachand F, Vanoosthuyse V. Senataxin homologue Sen1 is required for efficient termination of RNA polymerase III transcription. EMBO J 2019; 38:e101955. [PMID: 31294478 DOI: 10.15252/embj.2019101955] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Revised: 06/03/2019] [Accepted: 06/11/2019] [Indexed: 01/13/2023] Open
Abstract
R-loop disassembly by the human helicase Senataxin contributes to genome integrity and to proper transcription termination at a subset of RNA polymerase II genes. Whether Senataxin also contributes to transcription termination at other classes of genes has remained unclear. Here, we show that Sen1, one of two fission yeast homologues of Senataxin, promotes efficient termination of RNA polymerase III (RNAP3) transcription in vivo. In the absence of Sen1, RNAP3 accumulates downstream of RNAP3-transcribed genes and produces long exosome-sensitive 3'-extended transcripts. Importantly, neither of these defects was affected by the removal of R-loops. The finding that Sen1 acts as an ancillary factor for RNAP3 transcription termination in vivo challenges the pre-existing view that RNAP3 terminates transcription autonomously. We propose that Sen1 is a cofactor for transcription termination that has been co-opted by different RNA polymerases in the course of evolution.
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Affiliation(s)
- Julieta Rivosecchi
- Laboratoire de Biologie et Modélisation de la Cellule, Université de Lyon, CNRS, UMR 5239, Ecole Normale Supérieure de Lyon, Université Claude Bernard Lyon 1, Lyon, France
| | - Marc Larochelle
- Département de Biochimie, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Camille Teste
- Laboratoire de Biologie et Modélisation de la Cellule, Université de Lyon, CNRS, UMR 5239, Ecole Normale Supérieure de Lyon, Université Claude Bernard Lyon 1, Lyon, France
| | - Frédéric Grenier
- Département de Biochimie, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Amélie Malapert
- Laboratoire de Biologie et Modélisation de la Cellule, Université de Lyon, CNRS, UMR 5239, Ecole Normale Supérieure de Lyon, Université Claude Bernard Lyon 1, Lyon, France
| | - Emiliano P Ricci
- Laboratoire de Biologie et Modélisation de la Cellule, Université de Lyon, CNRS, UMR 5239, Ecole Normale Supérieure de Lyon, Université Claude Bernard Lyon 1, Lyon, France
| | - Pascal Bernard
- Laboratoire de Biologie et Modélisation de la Cellule, Université de Lyon, CNRS, UMR 5239, Ecole Normale Supérieure de Lyon, Université Claude Bernard Lyon 1, Lyon, France
| | - François Bachand
- Département de Biochimie, Université de Sherbrooke, Sherbrooke, QC, Canada.,Centre de Recherche du CHUS, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Vincent Vanoosthuyse
- Laboratoire de Biologie et Modélisation de la Cellule, Université de Lyon, CNRS, UMR 5239, Ecole Normale Supérieure de Lyon, Université Claude Bernard Lyon 1, Lyon, France
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35
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Pooled clone collections by multiplexed CRISPR-Cas12a-assisted gene tagging in yeast. Nat Commun 2019; 10:2960. [PMID: 31273196 PMCID: PMC6609715 DOI: 10.1038/s41467-019-10816-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2018] [Accepted: 05/31/2019] [Indexed: 12/27/2022] Open
Abstract
Clone collections of modified strains (“libraries”) are a major resource for systematic studies with the yeast Saccharomyces cerevisiae. Construction of such libraries is time-consuming, costly and confined to the genetic background of a specific yeast strain. To overcome these limitations, we present CRISPR-Cas12a (Cpf1)-assisted tag library engineering (CASTLING) for multiplexed strain construction. CASTLING uses microarray-synthesized oligonucleotide pools and in vitro recombineering to program the genomic insertion of long DNA constructs via homologous recombination. One simple transformation yields pooled libraries with >90% of correctly tagged clones. Up to several hundred genes can be tagged in a single step and, on a genomic scale, approximately half of all genes are tagged with only ~10-fold oversampling. We report several parameters that affect tagging success and provide a quantitative targeted next-generation sequencing method to analyze such pooled collections. Thus, CASTLING unlocks avenues for increasing throughput in functional genomics and cell biology research. Construction of yeast libraries is time-consuming, costly and limited to the genetic background of the chosen strain. Here the authors present CASTLING which uses CRISPR-Cas12a and oligonucleotide pools to rapidly generate pooled libraries with large insertions such as fluorescent protein tags.
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Abstract
In all living organisms, the flow of genetic information is a two-step process: first DNA is transcribed into RNA, which is subsequently used as template for protein synthesis during translation. In bacteria, archaea and eukaryotes, transcription is carried out by multi-subunit RNA polymerases (RNAPs) sharing a conserved architecture of the RNAP core. RNAPs catalyse the highly accurate polymerisation of RNA from NTP building blocks, utilising DNA as template, being assisted by transcription factors during the initiation, elongation and termination phase of transcription. The complexity of this highly dynamic process is reflected in the intricate network of protein-protein and protein-nucleic acid interactions in transcription complexes and the substantial conformational changes of the RNAP as it progresses through the transcription cycle.In this chapter, we will first briefly describe the early work that led to the discovery of multisubunit RNAPs. We will then discuss the three-dimensional organisation of RNAPs from the bacterial, archaeal and eukaryotic domains of life, highlighting the conserved nature, but also the domain-specific features of the transcriptional apparatus. Another section will focus on transcription factors and their role in regulating the RNA polymerase throughout the different phases of the transcription cycle. This includes a discussion of the molecular mechanisms and dynamic events that govern transcription initiation, elongation and termination.
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Chen J, Morita T, Gottesman S. Regulation of Transcription Termination of Small RNAs and by Small RNAs: Molecular Mechanisms and Biological Functions. Front Cell Infect Microbiol 2019; 9:201. [PMID: 31249814 PMCID: PMC6582626 DOI: 10.3389/fcimb.2019.00201] [Citation(s) in RCA: 52] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2019] [Accepted: 05/23/2019] [Indexed: 01/19/2023] Open
Abstract
Accurate and efficient transcription termination is an important step for cells to generate functional RNA transcripts. In bacteria, two mechanisms are responsible for terminating transcription: intrinsic (Rho-independent) termination and Rho-dependent termination. Growing examples suggest that neither type of transcription termination is static, but instead are highly dynamic and regulated. Regulatory small RNAs (sRNAs) are key players in bacterial stress responses, are frequently expressed under specific growth conditions, and are predominantly terminated through the intrinsic termination mechanism. Once made, sRNAs can base-pair with mRNA targets and regulate mRNA translation and stability. Recent findings suggest that alterations in the efficiency of intrinsic termination for sRNAs under various growth conditions may affect the availability of a given sRNA and the ability of the sRNA to function properly. Moreover, alterations of mRNA structure, translation, and accessibility by sRNAs have the potential to impact the access of Rho factor to mRNAs and thus termination of the mRNA. Indeed, recent studies have revealed that some sRNAs can modulate target gene expression by stimulating or inhibiting Rho-dependent termination, thus expanding the regulatory power of bacterial sRNAs. Here we review the current knowledge on intrinsic termination of sRNAs and sRNA-mediated Rho-dependent termination of protein coding genes in bacteria.
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Affiliation(s)
- Jiandong Chen
- Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, Bethesda, MD, United States
| | - Teppei Morita
- Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, Bethesda, MD, United States.,Faculty of Pharmaceutical Sciences, Suzuka University of Medical Sciences, Suzuka, Japan
| | - Susan Gottesman
- Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, Bethesda, MD, United States
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The A12.2 Subunit Is an Intrinsic Destabilizer of the RNA Polymerase I Elongation Complex. Biophys J 2019; 114:2507-2515. [PMID: 29874602 DOI: 10.1016/j.bpj.2018.04.015] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Revised: 03/20/2018] [Accepted: 04/10/2018] [Indexed: 01/25/2023] Open
Abstract
Despite sharing a highly conserved core architecture with their prokaryotic counterparts, eukaryotic multisubunit RNA polymerases (Pols) have undergone structural divergence and biological specialization. Interesting examples of structural divergence are the A12.2 and C11 subunits of Pols I and III, respectively. Whereas all known cellular Pols possess cognate protein factors that stimulate cleavage of the nascent RNA, Pols I and III have incorporated their cleavage factors as bona fide subunits. Although it is not yet clear why these polymerases have incorporated their cleavage factors as subunits, a picture is emerging that identifies roles for these subunits beyond providing nucleolytic activity. Specifically, it appears that both A12.2 and C11 are required for efficient termination of transcription by Pols I and III. Given that termination involves destabilization of the elongation complex (EC), we tested whether A12.2 influences stability of the Pol I EC. Using, to our knowledge, a novel assay to measure EC dissociation kinetics, we have determined that A12.2 is an intrinsic destabilizer of the Pol I EC. In addition, the salt concentration dependence of Pol I EC dissociation kinetics suggests that A12.2 alters electrostatic interactions within the EC. Importantly, these data present a mechanistic basis for the requirement of A12.2 in Pol I termination. Combined with recent work demonstrating the direct involvement of A12.2 in Pol I nucleotide incorporation, this study further supports the concept that A12.2 cannot be viewed solely as a cleavage factor.
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Reines D. A fluorescent assay for the genetic dissection of the RNA polymerase II termination machinery. Methods 2019; 159-160:124-128. [PMID: 30616008 DOI: 10.1016/j.ymeth.2018.12.011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Revised: 12/27/2018] [Accepted: 12/28/2018] [Indexed: 01/25/2023] Open
Abstract
RNA polymerase II is a highly processive enzyme that synthesizes mRNAs and some non-protein coding RNAs. Termination of transcription, which entails release of the transcript and disengagement of the polymerase, requires an active process. In yeast, there are at least two multi-protein complexes needed for termination of transcription, depending upon which class of RNAs are being acted upon. In general, the two classes are relatively short non-coding RNAs (e.g. snoRNAs) and relatively long mRNAs, although there are exceptions. Here, a procedure is described in which defective termination can be detected in living cells, resulting in a method that allows strains with mutations in termination factors or cis-acting sequences, to be identified and recovered. The strategy employs a reporter plasmid with a galactose inducible promoter driving transcription of green fluorescent protein which yields highly fluorescent cells. When a test terminator is inserted between the promoter and the fluorescent protein reading frame, cells fail to fluoresce. Mutant strains that have lost termination capability, so called terminator-override mutants, gain expression of the fluorescent protein and can be collected by fluorescence activated cell sorting. The strategy is robust since acquisition of fluorescence is a positive trait that has a low probability of happening adventitiously. Live mutant cells can easily be cloned from the population of positive candidates. Flow sorting is a sensitive, high-throughput detection step capable of discovering spontaneous mutations in yeast with high fidelity.
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Affiliation(s)
- Daniel Reines
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322, United States.
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40
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It's all about the T: transcription termination in archaea. Biochem Soc Trans 2019; 47:461-468. [PMID: 30783016 DOI: 10.1042/bst20180557] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Revised: 01/25/2019] [Accepted: 01/28/2019] [Indexed: 01/06/2023]
Abstract
One of the most fundamental biological processes driving all life on earth is transcription. The, at first glance, relatively simple cycle is divided into three stages: initiation at the promoter site, elongation throughout the open reading frame, and finally termination and product release at the terminator. In all three processes, motifs of the template DNA and protein factors of the transcription machinery including the multisubunit polymerase itself as well as a broad range of associated transcription factors work together and mutually influence each other. Despite several decades of research, this interplay holds delicate mechanistic and structural details as well as interconnections yet to be explored. One of the surprising characteristics of archaeal biology is the use of eukaryotic-like information processing systems against a backdrop of a bacterial-like genome. Archaeal genomes usually comprise main chromosomes alongside chromosomal plasmids, and the genetic information is encoded in single transcriptional units as well as in multicistronic operons alike their bacterial counterparts. Moreover, archaeal genomes are densely packed and this necessitates a tight regulation of transcription and especially assured termination events in order to prevent read-through into downstream coding regions and the accumulation of antisense transcripts.
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41
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Contrasting roles of the RSC and ISW1/CHD1 chromatin remodelers in RNA polymerase II elongation and termination. Genome Res 2019; 29:407-417. [PMID: 30683752 PMCID: PMC6396426 DOI: 10.1101/gr.242032.118] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Accepted: 01/22/2019] [Indexed: 12/17/2022]
Abstract
Most yeast genes have a nucleosome-depleted region (NDR) at the promoter and an array of regularly spaced nucleosomes phased relative to the transcription start site. We have examined the interplay between RSC (a conserved essential SWI/SNF-type complex that determines NDR size) and the ISW1, CHD1, and ISW2 nucleosome spacing enzymes in chromatin organization and transcription, using isogenic strains lacking all combinations of these enzymes. The contributions of these remodelers to chromatin organization are largely combinatorial, distinct, and nonredundant, supporting a model in which the +1 nucleosome is positioned by RSC and then used as a reference nucleosome by the spacing enzymes. Defective chromatin organization correlates with altered RNA polymerase II (Pol II) distribution. RSC-depleted cells exhibit low levels of elongating Pol II and high levels of terminating Pol II, consistent with defects in both termination and initiation, suggesting that RSC facilitates both. Cells lacking both ISW1 and CHD1 show the opposite Pol II distribution, suggesting elongation and termination defects. These cells have extremely disrupted chromatin, with high levels of closely packed dinucleosomes involving the second (+2) nucleosome. We propose that ISW1 and CHD1 facilitate Pol II elongation by separating closely packed nucleosomes.
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42
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Fouqueau T, Blombach F, Cackett G, Carty AE, Matelska DM, Ofer S, Pilotto S, Phung DK, Werner F. The cutting edge of archaeal transcription. Emerg Top Life Sci 2018; 2:517-533. [PMID: 33525828 PMCID: PMC7289017 DOI: 10.1042/etls20180014] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Revised: 10/01/2018] [Accepted: 10/04/2018] [Indexed: 12/26/2022]
Abstract
The archaeal RNA polymerase (RNAP) is a double-psi β-barrel enzyme closely related to eukaryotic RNAPII in terms of subunit composition and architecture, promoter elements and basal transcription factors required for the initiation and elongation phase of transcription. Understanding archaeal transcription is, therefore, key to delineate the universally conserved fundamental mechanisms of transcription as well as the evolution of the archaeo-eukaryotic transcription machineries. The dynamic interplay between RNAP subunits, transcription factors and nucleic acids dictates the activity of RNAP and ultimately gene expression. This review focusses on recent progress in our understanding of (i) the structure, function and molecular mechanisms of known and less characterized factors including Elf1 (Elongation factor 1), NusA (N-utilization substance A), TFS4, RIP and Eta, and (ii) their evolution and phylogenetic distribution across the expanding tree of Archaea.
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Affiliation(s)
- Thomas Fouqueau
- RNAP laboratory, Institute of Structural and Molecular Biology, Division of Biosciences, University College London, Gower Street, London WC1E 6BT, U.K
| | - Fabian Blombach
- RNAP laboratory, Institute of Structural and Molecular Biology, Division of Biosciences, University College London, Gower Street, London WC1E 6BT, U.K
| | - Gwenny Cackett
- RNAP laboratory, Institute of Structural and Molecular Biology, Division of Biosciences, University College London, Gower Street, London WC1E 6BT, U.K
| | - Alice E Carty
- RNAP laboratory, Institute of Structural and Molecular Biology, Division of Biosciences, University College London, Gower Street, London WC1E 6BT, U.K
| | - Dorota M Matelska
- RNAP laboratory, Institute of Structural and Molecular Biology, Division of Biosciences, University College London, Gower Street, London WC1E 6BT, U.K
| | - Sapir Ofer
- RNAP laboratory, Institute of Structural and Molecular Biology, Division of Biosciences, University College London, Gower Street, London WC1E 6BT, U.K
| | - Simona Pilotto
- RNAP laboratory, Institute of Structural and Molecular Biology, Division of Biosciences, University College London, Gower Street, London WC1E 6BT, U.K
| | - Duy Khanh Phung
- RNAP laboratory, Institute of Structural and Molecular Biology, Division of Biosciences, University College London, Gower Street, London WC1E 6BT, U.K
| | - Finn Werner
- RNAP laboratory, Institute of Structural and Molecular Biology, Division of Biosciences, University College London, Gower Street, London WC1E 6BT, U.K
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43
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Nomura Y, Roston D, Montemayor EJ, Cui Q, Butcher SE. Structural and mechanistic basis for preferential deadenylation of U6 snRNA by Usb1. Nucleic Acids Res 2018; 46:11488-11501. [PMID: 30215753 PMCID: PMC6265477 DOI: 10.1093/nar/gky812] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Revised: 08/27/2018] [Accepted: 08/29/2018] [Indexed: 01/08/2023] Open
Abstract
Post-transcriptional modification of snRNA is central to spliceosome function. Usb1 is an exoribonuclease that shortens the oligo-uridine tail of U6 snRNA, resulting in a terminal 2',3' cyclic phosphate group in most eukaryotes, including humans. Loss of function mutations in human Usb1 cause the rare disorder poikiloderma with neutropenia (PN), and result in U6 snRNAs with elongated 3' ends that are aberrantly adenylated. Here, we show that human Usb1 removes 3' adenosines with 20-fold greater efficiency than uridines, which explains the presence of adenylated U6 snRNAs in cells lacking Usb1. We determined three high-resolution co-crystal structures of Usb1: wild-type Usb1 bound to the substrate analog adenosine 5'-monophosphate, and an inactive mutant bound to RNAs with a 3' terminal adenosine and uridine. These structures, along with QM/MM MD simulations of the catalytic mechanism, illuminate the molecular basis for preferential deadenylation of U6 snRNA. The extent of Usb1 processing is influenced by the secondary structure of U6 snRNA.
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Affiliation(s)
- Yuichiro Nomura
- Department of Biochemistry, University of Wisconsin, Madison, WI 53706, USA
| | - Daniel Roston
- Department of Biochemistry, University of Wisconsin, Madison, WI 53706, USA
- Department of Chemistry, University of Wisconsin, Madison, WI 53706, USA
| | - Eric J Montemayor
- Department of Biochemistry, University of Wisconsin, Madison, WI 53706, USA
- Department of Biomolecular Chemistry, University of Wisconsin, Madison, WI 53706, USA
| | - Qiang Cui
- Department of Chemistry, University of Wisconsin, Madison, WI 53706, USA
| | - Samuel E Butcher
- Department of Biochemistry, University of Wisconsin, Madison, WI 53706, USA
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44
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A Drosophila CRISPR/Cas9 Toolkit for Conditionally Manipulating Gene Expression in the Prothoracic Gland as a Test Case for Polytene Tissues. G3-GENES GENOMES GENETICS 2018; 8:3593-3605. [PMID: 30213867 PMCID: PMC6222582 DOI: 10.1534/g3.118.200539] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Targeting gene function with spatial or temporal specificity is a key goal in molecular genetics. CRISPR-Cas9 has greatly facilitated this strategy, but some standard approaches are problematic. For instance, simple tissue-specific or global overexpression of Cas9 can cause significant lethality or developmental delays even in the absence of gRNAs. In particular, we found that Gal4-mediated expression of UAS-Cas9 in the Drosophila prothoracic gland (PG) was not a suitable strategy to disrupt gene expression, since Cas9 alone caused widespread lethality. The PG is widely used for studying endocrine gland function during animal development, but tools validating PG-specific RNAi phenotypes are lacking. Here, we present a collection of modular gateway-compatible CRISPR-Cas9 tools that allow precise modulation of target gene activity with temporal and spatial specificity. We also demonstrate that Cas9 fused to the progesterone ligand-binding domain can be used to activate gene expression via RU486. Using these approaches, we were able to avoid the lethality associated with simple GAL4-mediated overexpression of Cas9 in the PG. Given that the PG is a polytene tissue, we conclude that these tools work effectively in endoreplicating cells where Cas9 has to target multiple copies of the same locus. Our toolkit can be easily adapted for other tissues and can be used both for gain- and loss-of-function studies.
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45
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Roy KR, Smith JD, Vonesch SC, Lin G, Tu CS, Lederer AR, Chu A, Suresh S, Nguyen M, Horecka J, Tripathi A, Burnett WT, Morgan MA, Schulz J, Orsley KM, Wei W, Aiyar RS, Davis RW, Bankaitis VA, Haber JE, Salit ML, St Onge RP, Steinmetz LM. Multiplexed precision genome editing with trackable genomic barcodes in yeast. Nat Biotechnol 2018; 36:512-520. [PMID: 29734294 PMCID: PMC5990450 DOI: 10.1038/nbt.4137] [Citation(s) in RCA: 102] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2017] [Accepted: 03/12/2018] [Indexed: 12/26/2022]
Abstract
Our understanding of how genotype controls phenotype is limited by the scale at which we can precisely alter the genome and assess the phenotypic consequences of each perturbation. Here we describe a CRISPR-Cas9-based method for multiplexed accurate genome editing with short, trackable, integrated cellular barcodes (MAGESTIC) in Saccharomyces cerevisiae. MAGESTIC uses array-synthesized guide-donor oligos for plasmid-based high-throughput editing and features genomic barcode integration to prevent plasmid barcode loss and to enable robust phenotyping. We demonstrate that editing efficiency can be increased more than fivefold by recruiting donor DNA to the site of breaks using the LexA-Fkh1p fusion protein. We performed saturation editing of the essential gene SEC14 and identified amino acids critical for chemical inhibition of lipid signaling. We also constructed thousands of natural genetic variants, characterized guide mismatch tolerance at the genome scale, and ascertained that cryptic Pol III termination elements substantially reduce guide efficacy. MAGESTIC will be broadly useful to uncover the genetic basis of phenotypes in yeast.
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Affiliation(s)
- Kevin R. Roy
- Stanford Genome Technology Center, Stanford University, Palo Alto, California, USA
- Genome-Scale Measurements Group, Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland, USA
- Joint Initiative for Metrology in Biology, Stanford, California, USA
- Department of Genetics, Stanford University School of Medicine, Stanford, California, USA
| | - Justin D. Smith
- Stanford Genome Technology Center, Stanford University, Palo Alto, California, USA
- Department of Genetics, Stanford University School of Medicine, Stanford, California, USA
| | - Sibylle C. Vonesch
- European Molecular Biology Laboratory (EMBL), Genome Biology Unit, Heidelberg, Germany
| | - Gen Lin
- European Molecular Biology Laboratory (EMBL), Genome Biology Unit, Heidelberg, Germany
| | - Chelsea Szu Tu
- European Molecular Biology Laboratory (EMBL), Genome Biology Unit, Heidelberg, Germany
| | - Alex R. Lederer
- European Molecular Biology Laboratory (EMBL), Genome Biology Unit, Heidelberg, Germany
| | - Angela Chu
- Stanford Genome Technology Center, Stanford University, Palo Alto, California, USA
- Department of Biochemistry, Stanford University School of Medicine, Stanford, California, USA
| | - Sundari Suresh
- Stanford Genome Technology Center, Stanford University, Palo Alto, California, USA
- Department of Biochemistry, Stanford University School of Medicine, Stanford, California, USA
| | - Michelle Nguyen
- Stanford Genome Technology Center, Stanford University, Palo Alto, California, USA
- Department of Genetics, Stanford University School of Medicine, Stanford, California, USA
| | - Joe Horecka
- Stanford Genome Technology Center, Stanford University, Palo Alto, California, USA
- Department of Biochemistry, Stanford University School of Medicine, Stanford, California, USA
| | - Ashutosh Tripathi
- Department of Molecular and Cellular Medicine, Texas A&M Health Science Center, College Station, Texas, USA
| | - Wallace T. Burnett
- Stanford Genome Technology Center, Stanford University, Palo Alto, California, USA
- Department of Genetics, Stanford University School of Medicine, Stanford, California, USA
| | - Maddison A. Morgan
- Stanford Genome Technology Center, Stanford University, Palo Alto, California, USA
- Department of Genetics, Stanford University School of Medicine, Stanford, California, USA
| | - Julia Schulz
- Stanford Genome Technology Center, Stanford University, Palo Alto, California, USA
- Department of Genetics, Stanford University School of Medicine, Stanford, California, USA
| | - Kevin M. Orsley
- Stanford Genome Technology Center, Stanford University, Palo Alto, California, USA
- Department of Genetics, Stanford University School of Medicine, Stanford, California, USA
| | - Wu Wei
- Stanford Genome Technology Center, Stanford University, Palo Alto, California, USA
- Department of Genetics, Stanford University School of Medicine, Stanford, California, USA
| | - Raeka S. Aiyar
- Stanford Genome Technology Center, Stanford University, Palo Alto, California, USA
| | - Ronald W. Davis
- Stanford Genome Technology Center, Stanford University, Palo Alto, California, USA
- Department of Genetics, Stanford University School of Medicine, Stanford, California, USA
- Department of Biochemistry, Stanford University School of Medicine, Stanford, California, USA
| | - Vytas A. Bankaitis
- Department of Molecular and Cellular Medicine, Texas A&M Health Science Center, College Station, Texas, USA
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas, USA
- Department of Chemistry, Texas A&M University, College Station, Texas, USA
| | - James E. Haber
- Rosenstiel Basic Medical Sciences Research Center and Department of Biology, Brandeis University, Waltham, Massachusetts, USA
| | - Marc L. Salit
- Genome-Scale Measurements Group, Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland, USA
- Joint Initiative for Metrology in Biology, Stanford, California, USA
| | - Robert P. St Onge
- Stanford Genome Technology Center, Stanford University, Palo Alto, California, USA
- Department of Biochemistry, Stanford University School of Medicine, Stanford, California, USA
| | - Lars M. Steinmetz
- Stanford Genome Technology Center, Stanford University, Palo Alto, California, USA
- Joint Initiative for Metrology in Biology, Stanford, California, USA
- Department of Genetics, Stanford University School of Medicine, Stanford, California, USA
- European Molecular Biology Laboratory (EMBL), Genome Biology Unit, Heidelberg, Germany
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46
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Patsali P, Papasavva P, Stephanou C, Christou S, Sitarou M, Antoniou MN, Lederer CW, Kleanthous M. Short-hairpin RNA against aberrant HBBIVSI-110(G>A) mRNA restores β-globin levels in a novel cell model and acts as mono- and combination therapy for β-thalassemia in primary hematopoietic stem cells. Haematologica 2018; 103:e419-e423. [PMID: 29700171 DOI: 10.3324/haematol.2018.189357] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Affiliation(s)
- Petros Patsali
- Department of Molecular Genetics Thalassaemia, The Cyprus Institute of Neurology and Genetics, Nicosia, Cyprus.,Department of Medical and Molecular Genetics, King's College London, UK
| | - Panayiota Papasavva
- Department of Molecular Genetics Thalassaemia, The Cyprus Institute of Neurology and Genetics, Nicosia, Cyprus.,Cyprus School of Molecular Medicine, Nicosia, Cyprus
| | - Coralea Stephanou
- Department of Molecular Genetics Thalassaemia, The Cyprus Institute of Neurology and Genetics, Nicosia, Cyprus.,Department of Medical and Molecular Genetics, King's College London, UK
| | | | | | | | - Carsten W Lederer
- Department of Molecular Genetics Thalassaemia, The Cyprus Institute of Neurology and Genetics, Nicosia, Cyprus .,Cyprus School of Molecular Medicine, Nicosia, Cyprus
| | - Marina Kleanthous
- Department of Molecular Genetics Thalassaemia, The Cyprus Institute of Neurology and Genetics, Nicosia, Cyprus.,Cyprus School of Molecular Medicine, Nicosia, Cyprus
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47
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Didychuk AL, Butcher SE, Brow DA. The life of U6 small nuclear RNA, from cradle to grave. RNA (NEW YORK, N.Y.) 2018; 24:437-460. [PMID: 29367453 PMCID: PMC5855946 DOI: 10.1261/rna.065136.117] [Citation(s) in RCA: 67] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Removal of introns from precursor messenger RNA (pre-mRNA) and some noncoding transcripts is an essential step in eukaryotic gene expression. In the nucleus, this process of RNA splicing is carried out by the spliceosome, a multi-megaDalton macromolecular machine whose core components are conserved from yeast to humans. In addition to many proteins, the spliceosome contains five uridine-rich small nuclear RNAs (snRNAs) that undergo an elaborate series of conformational changes to correctly recognize the splice sites and catalyze intron removal. Decades of biochemical and genetic data, along with recent cryo-EM structures, unequivocally demonstrate that U6 snRNA forms much of the catalytic core of the spliceosome and is highly dynamic, interacting with three snRNAs, the pre-mRNA substrate, and >25 protein partners throughout the splicing cycle. This review summarizes the current state of knowledge on how U6 snRNA is synthesized, modified, incorporated into snRNPs and spliceosomes, recycled, and degraded.
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Affiliation(s)
- Allison L Didychuk
- Department of Biochemistry, University of Wisconsin, Madison, Wisconsin 53706, USA
| | - Samuel E Butcher
- Department of Biochemistry, University of Wisconsin, Madison, Wisconsin 53706, USA
| | - David A Brow
- Department of Biomolecular Chemistry, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin 53706, USA
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48
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Leśniewska E, Boguta M. Novel layers of RNA polymerase III control affecting tRNA gene transcription in eukaryotes. Open Biol 2017; 7:rsob.170001. [PMID: 28228471 PMCID: PMC5356446 DOI: 10.1098/rsob.170001] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2017] [Accepted: 01/31/2017] [Indexed: 12/20/2022] Open
Abstract
RNA polymerase III (Pol III) transcribes a limited set of short genes in eukaryotes producing abundant small RNAs, mostly tRNA. The originally defined yeast Pol III transcriptome appears to be expanding owing to the application of new methods. Also, several factors required for assembly and nuclear import of Pol III complex have been identified recently. Models of Pol III based on cryo-electron microscopy reconstructions of distinct Pol III conformations reveal unique features distinguishing Pol III from other polymerases. Novel concepts concerning Pol III functioning involve recruitment of general Pol III-specific transcription factors and distinctive mechanisms of transcription initiation, elongation and termination. Despite the short length of Pol III transcription units, mapping of transcriptionally active Pol III with nucleotide resolution has revealed strikingly uneven polymerase distribution along all genes. This may be related, at least in part, to the transcription factors bound at the internal promoter regions. Pol III uses also a specific negative regulator, Maf1, which binds to polymerase under stress conditions; however, a subset of Pol III genes is not controlled by Maf1. Among other RNA polymerases, Pol III machinery represents unique features related to a short transcript length and high transcription efficiency.
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Affiliation(s)
- Ewa Leśniewska
- Department of Genetics, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, 02-106 Warsaw, Poland
| | - Magdalena Boguta
- Department of Genetics, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, 02-106 Warsaw, Poland
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Shukla A, Bhargava P. Regulation of tRNA gene transcription by the chromatin structure and nucleosome dynamics. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2017; 1861:295-309. [PMID: 29313808 DOI: 10.1016/j.bbagrm.2017.11.008] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2017] [Revised: 11/27/2017] [Accepted: 11/27/2017] [Indexed: 01/19/2023]
Abstract
The short, non-coding genes transcribed by the RNA polymerase (pol) III, necessary for survival of a cell, need to be repressed under the stress conditions in vivo. The pol III-transcribed genes have adopted several novel chromatin-based regulatory mechanisms to their advantage. In the budding yeast, the sub-nucleosomal size tRNA genes are found in the nucleosome-free regions, flanked by positioned nucleosomes at both the ends. With their chromosomes-wide distribution, all tRNA genes have a different chromatin context. A single nucleosome dynamics controls the accessibility of the genes for transcription. This dynamics operates under the influence of several chromatin modifiers in a gene-specific manner, giving the scope for differential regulation of even the isogenes within a tRNA gene family. The chromatin structure around the pol III-transcribed genes provides a context conducive for steady-state transcription as well as gene-specific transcriptional regulation upon signaling from the environmental cues. This article is part of a Special Issue entitled: SI: Regulation of tRNA synthesis and modification in physiological conditions and disease edited by Dr. Boguta Magdalena.
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Affiliation(s)
- Ashutosh Shukla
- Centre for Cellular and Molecular Biology (Council of Scientific and Industrial Research), Uppal Road, Hyderabad 500007, India
| | - Purnima Bhargava
- Centre for Cellular and Molecular Biology (Council of Scientific and Industrial Research), Uppal Road, Hyderabad 500007, India.
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Gao Z, Herrera-Carrillo E, Berkhout B. Delineation of the Exact Transcription Termination Signal for Type 3 Polymerase III. MOLECULAR THERAPY-NUCLEIC ACIDS 2017; 10:36-44. [PMID: 29499947 PMCID: PMC5725217 DOI: 10.1016/j.omtn.2017.11.006] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/22/2017] [Revised: 11/15/2017] [Accepted: 11/15/2017] [Indexed: 12/29/2022]
Abstract
Type 3 Pol III promoters such as U6 are widely used for expression of small RNAs, including short hairpin RNA for RNAi applications and guide RNA in CRISPR genome-editing platforms. RNA polymerase III uses a T-stretch as termination signal, but the exact properties have not been thoroughly investigated. Here, we systematically measured the in vivo termination efficiency and the actual site of termination for different T-stretch signals in three commonly used human Pol III promoters (U6, 7SK, and H1). Both the termination efficiency and the actual termination site depend on the T-stretch signal. The T4 signal acts as minimal terminator, but full termination efficiency is reached only with a T-stretch of ≥6. The termination site within the T-stretch is quite heterogeneous, and consequently small RNAs have a variable U-tail of 1–6 nucleotides. We further report that such variable U-tails can have a significant negative effect on the functionality of the crRNA effector of the CRISPR-AsCpf1 system. We next improved these crRNAs by insertion of the HDV ribozyme to avoid U-tails. This study provides detailed design guidelines for small RNA expression cassettes based on Pol III.
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Affiliation(s)
- Zongliang Gao
- Laboratory of Experimental Virology, Department of Medical Microbiology, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands
| | - Elena Herrera-Carrillo
- Laboratory of Experimental Virology, Department of Medical Microbiology, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands
| | - Ben Berkhout
- Laboratory of Experimental Virology, Department of Medical Microbiology, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands.
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