1
|
Franco G, Taillebourg E, Delfino E, Homolka D, Gueguen N, Brasset E, Pandey RR, Pillai RS, Fauvarque MO. The catalytic-dead Pcif1 regulates gene expression and fertility in Drosophila. RNA (NEW YORK, N.Y.) 2023; 29:609-619. [PMID: 36754578 PMCID: PMC10158991 DOI: 10.1261/rna.079192.122] [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: 04/12/2022] [Accepted: 01/09/2023] [Indexed: 05/06/2023]
Abstract
Eukaryotic mRNAs are modified at the 5' end with a methylated guanosine (m7G) that is attached to the transcription start site (TSS) nucleotide. The TSS nucleotide is 2'-O-methylated (Nm) by CMTR1 in organisms ranging from insects to human. In mammals, the TSS adenosine can be further N 6 -methylated by RNA polymerase II phosphorylated CTD-interacting factor 1 (PCIF1) to create m6Am. Curiously, the fly ortholog of mammalian PCIF1 is demonstrated to be catalytic-dead, and its functions are not known. Here, we show that Pcif1 mutant flies display a reduced fertility which is particularly marked in females. Deep sequencing analysis of Pcif1 mutant ovaries revealed transcriptome changes with a notable increase in expression of genes belonging to the mitochondrial ATP synthetase complex. Furthermore, the Pcif1 protein is distributed along euchromatic regions of polytene chromosomes, and the Pcif1 mutation behaved as a modifier of position-effect-variegation (PEV) suppressing the heterochromatin-dependent silencing of the white gene. Similar or stronger changes in the transcriptome and PEV phenotype were observed in flies that expressed a cytosolic version of Pcif1. These results point to a nuclear cotranscriptional gene regulatory role for the catalytic-dead fly Pcif1 that is probably based on its conserved ability to interact with the RNA polymerase II carboxy-terminal domain.
Collapse
Affiliation(s)
- Giulia Franco
- Université Grenoble Alpes, CEA, INSERM, BGE, F-38000 Grenoble, France
| | | | - Elena Delfino
- Department of Molecular Biology, Science III, University of Geneva, CH-1211 Geneva 4, Switzerland
| | - David Homolka
- Department of Molecular Biology, Science III, University of Geneva, CH-1211 Geneva 4, Switzerland
| | - Nathalie Gueguen
- iGReD, Université Clermont Auvergne, CNRS, INSERM, Faculté de Médecine, 63000 Clermont-Ferrand, France
| | - Emilie Brasset
- iGReD, Université Clermont Auvergne, CNRS, INSERM, Faculté de Médecine, 63000 Clermont-Ferrand, France
| | - Radha Raman Pandey
- Department of Molecular Biology, Science III, University of Geneva, CH-1211 Geneva 4, Switzerland
| | - Ramesh S Pillai
- Department of Molecular Biology, Science III, University of Geneva, CH-1211 Geneva 4, Switzerland
| | | |
Collapse
|
2
|
Despic V, Jaffrey SR. mRNA ageing shapes the Cap2 methylome in mammalian mRNA. Nature 2023; 614:358-366. [PMID: 36725932 PMCID: PMC9891201 DOI: 10.1038/s41586-022-05668-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Accepted: 12/16/2022] [Indexed: 02/03/2023]
Abstract
The mRNA cap structure is a major site of dynamic mRNA methylation. mRNA caps exist in either the Cap1 or Cap2 form, depending on the presence of 2'-O-methylation on the first transcribed nucleotide or both the first and second transcribed nucleotides, respectively1,2. However, the identity of Cap2-containing mRNAs and the function of Cap2 are unclear. Here we describe CLAM-Cap-seq, a method for transcriptome-wide mapping and quantification of Cap2. We find that unlike other epitranscriptomic modifications, Cap2 can occur on all mRNAs. Cap2 is formed through a slow continuous conversion of mRNAs from Cap1 to Cap2 as mRNAs age in the cytosol. As a result, Cap2 is enriched on long-lived mRNAs. Large increases in the abundance of Cap1 leads to activation of RIG-I, especially in conditions in which expression of RIG-I is increased. The methylation of Cap1 to Cap2 markedly reduces the ability of RNAs to bind to and activate RIG-I. The slow methylation rate of Cap2 allows Cap2 to accumulate on host mRNAs, yet ensures that low levels of Cap2 occur on newly expressed viral RNAs. Overall, these results reveal an immunostimulatory role for Cap1, and that Cap2 functions to reduce activation of the innate immune response.
Collapse
Affiliation(s)
- Vladimir Despic
- Department of Pharmacology, Weill Cornell Medicine, Cornell University, New York, NY, USA
| | - Samie R Jaffrey
- Department of Pharmacology, Weill Cornell Medicine, Cornell University, New York, NY, USA.
| |
Collapse
|
3
|
Yu D, Dai N, Wolf EJ, Corrêa IR, Zhou J, Wu T, Blumenthal RM, Zhang X, Cheng X. Enzymatic characterization of mRNA cap adenosine-N6 methyltransferase PCIF1 activity on uncapped RNAs. J Biol Chem 2022; 298:101751. [PMID: 35189146 PMCID: PMC8931429 DOI: 10.1016/j.jbc.2022.101751] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Revised: 02/15/2022] [Accepted: 02/16/2022] [Indexed: 02/08/2023] Open
Abstract
The phosphorylated RNA polymerase II CTD interacting factor 1 (PCIF1) is a methyltransferase that adds a methyl group to the N6-position of 2′O-methyladenosine (Am), generating N6, 2′O-dimethyladenosine (m6Am) when Am is the cap-proximal nucleotide. In addition, PCIF1 has ancillary methylation activities on internal adenosines (both A and Am), although with much lower catalytic efficiency relative to that of its preferred cap substrate. The PCIF1 preference for 2′O-methylated Am over unmodified A nucleosides is due mainly to increased binding affinity for Am. Importantly, it was recently reported that PCIF1 can methylate viral RNA. Although some viral RNA can be translated in the absence of a cap, it is unclear what roles PCIF1 modifications may play in the functionality of viral RNAs. Here we show, using in vitro assays of binding and methyltransfer, that PCIF1 binds an uncapped 5′-Am oligonucleotide with approximately the same affinity as that of a cap analog (KM = 0.4 versus 0.3 μM). In addition, PCIF1 methylates the uncapped 5′-Am with activity decreased by only fivefold to sixfold compared with its preferred capped substrate. We finally discuss the relationship between PCIF1-catalyzed RNA methylation, shown here to have broader substrate specificity than previously appreciated, and that of the RNA demethylase fat mass and obesity-associated protein (FTO), which demonstrates PCIF1-opposing activities on capped RNAs.
Collapse
Affiliation(s)
- Dan Yu
- Department of Epigenetics and Molecular Carcinogenesis, University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | - Nan Dai
- New England Biolabs, Inc, Ipswich, Massachusetts, USA
| | - Eric J Wolf
- New England Biolabs, Inc, Ipswich, Massachusetts, USA
| | - Ivan R Corrêa
- New England Biolabs, Inc, Ipswich, Massachusetts, USA
| | - Jujun Zhou
- Department of Epigenetics and Molecular Carcinogenesis, University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | - Tao Wu
- Department of Molecular & Human Genetics, Baylor College of Medicine, Houston, Texas, USA
| | - Robert M Blumenthal
- Department of Medical Microbiology and Immunology, and Program in Bioinformatics, The University of Toledo College of Medicine and Life Sciences, Toledo, Ohio, USA
| | - Xing Zhang
- Department of Epigenetics and Molecular Carcinogenesis, University of Texas MD Anderson Cancer Center, Houston, Texas, USA.
| | - Xiaodong Cheng
- Department of Epigenetics and Molecular Carcinogenesis, University of Texas MD Anderson Cancer Center, Houston, Texas, USA.
| |
Collapse
|
4
|
Methylation of viral mRNA cap structures by PCIF1 attenuates the antiviral activity of interferon-β. Proc Natl Acad Sci U S A 2021; 118:2025769118. [PMID: 34266951 DOI: 10.1073/pnas.2025769118] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Interferons induce cell-intrinsic responses associated with resistance to viral infection. To overcome the suppressive action of interferons and their effectors, viruses have evolved diverse mechanisms. Using vesicular stomatitis virus (VSV), we report that the host cell N6-adenosine messenger RNA (mRNA) cap methylase, phosphorylated C-terminal domain interacting factor 1 (PCIF1), attenuates the antiviral response. We employed cell-based and in vitro biochemical assays to demonstrate that PCIF1 efficiently modifies VSV mRNA cap structures to m7Gpppm6Am and define the substrate requirements for this modification. Functional assays revealed that the PCIF1-dependent modification of VSV mRNA cap structures is inert with regard to mRNA stability, translation, and viral infectivity but attenuates the antiviral effects of the treatment of cells with interferon-β. Cells lacking PCIF1 or expressing a catalytically inactive PCIF1 exhibit an augmented inhibition of viral replication and gene expression following interferon-β treatment. We further demonstrate that the mRNA cap structures of rabies and measles viruses are also modified by PCIF1 to m7Gpppm6Am This work identifies a function of PCIF1 and cap-proximal m6Am in attenuation of the host response to VSV infection that likely extends to other viruses.
Collapse
|
5
|
Methyltransferase-like 3 Modulates Severe Acute Respiratory Syndrome Coronavirus-2 RNA N6-Methyladenosine Modification and Replication. mBio 2021; 12:e0106721. [PMID: 34225491 PMCID: PMC8437041 DOI: 10.1128/mbio.01067-21] [Citation(s) in RCA: 53] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The coronavirus disease 2019 pandemic caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is an ongoing global public crisis. Although viral RNA modification has been reported based on the transcriptome architecture, the types and functions of RNA modification are still unknown. In this study, we evaluated the roles of RNA N6-methyladenosine (m6A) modification in SARS-CoV-2. Our methylated RNA immunoprecipitation sequencing (MeRIP-Seq) and Nanopore direct RNA sequencing (DRS) analysis showed that SARS-CoV-2 RNA contained m6A modification. Moreover, SARS-CoV-2 infection not only increased the expression of methyltransferase-like 3 (METTL3) but also altered its distribution. Modification of METTL3 expression by short hairpin RNA or plasmid transfection for knockdown or overexpression, respectively, affected viral replication. Furthermore, the viral key protein RdRp interacted with METTL3, and METTL3 was distributed in both the nucleus and cytoplasm in the presence of RdRp. RdRp appeared to modulate the sumoylation and ubiquitination of METTL3 via an unknown mechanism. Taken together, our findings demonstrated that the host m6A modification complex interacted with viral proteins to modulate SARS-CoV-2 replication.
Collapse
|
6
|
Ogino T, Green TJ. RNA Synthesis and Capping by Non-segmented Negative Strand RNA Viral Polymerases: Lessons From a Prototypic Virus. Front Microbiol 2019; 10:1490. [PMID: 31354644 PMCID: PMC6636387 DOI: 10.3389/fmicb.2019.01490] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Accepted: 06/14/2019] [Indexed: 12/26/2022] Open
Abstract
Non-segmented negative strand (NNS) RNA viruses belonging to the order Mononegavirales are highly diversified eukaryotic viruses including significant human pathogens, such as rabies, measles, Nipah, and Ebola. Elucidation of their unique strategies to replicate in eukaryotic cells is crucial to aid in developing anti-NNS RNA viral agents. Over the past 40 years, vesicular stomatitis virus (VSV), closely related to rabies virus, has served as a paradigm to study the fundamental molecular mechanisms of transcription and replication of NNS RNA viruses. These studies provided insights into how NNS RNA viruses synthesize 5'-capped mRNAs using their RNA-dependent RNA polymerase L proteins equipped with an unconventional mRNA capping enzyme, namely GDP polyribonucleotidyltransferase (PRNTase), domain. PRNTase or PRNTase-like domains are evolutionally conserved among L proteins of all known NNS RNA viruses and their related viruses belonging to Jingchuvirales, a newly established order, in the class Monjiviricetes, suggesting that they may have evolved from a common ancestor that acquired the unique capping system to replicate in a primitive eukaryotic host. This article reviews what has been learned from biochemical and structural studies on the VSV RNA biosynthesis machinery, and then focuses on recent advances in our understanding of regulatory and catalytic roles of the PRNTase domain in RNA synthesis and capping.
Collapse
Affiliation(s)
- Tomoaki Ogino
- Department of Molecular Biology and Microbiology, Case Western Reserve University School of Medicine, Cleveland, OH, United States
- Department of Inflammation and Immunity, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, United States
| | - Todd J. Green
- Department of Microbiology, School of Medicine, University of Alabama at Birmingham, Birmingham, AL, United States
| |
Collapse
|
7
|
Ogino T, Green TJ. Transcriptional Control and mRNA Capping by the GDP Polyribonucleotidyltransferase Domain of the Rabies Virus Large Protein. Viruses 2019; 11:E504. [PMID: 31159413 PMCID: PMC6631705 DOI: 10.3390/v11060504] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Revised: 05/24/2019] [Accepted: 05/30/2019] [Indexed: 12/11/2022] Open
Abstract
Rabies virus (RABV) is a causative agent of a fatal neurological disease in humans and animals. The large (L) protein of RABV is a multifunctional RNA-dependent RNA polymerase, which is one of the most attractive targets for developing antiviral agents. A remarkable homology of the RABV L protein to a counterpart in vesicular stomatitis virus, a well-characterized rhabdovirus, suggests that it catalyzes mRNA processing reactions, such as 5'-capping, cap methylation, and 3'-polyadenylation, in addition to RNA synthesis. Recent breakthroughs in developing in vitro RNA synthesis and capping systems with a recombinant form of the RABV L protein have led to significant progress in our understanding of the molecular mechanisms of RABV RNA biogenesis. This review summarizes functions of RABV replication proteins in transcription and replication, and highlights new insights into roles of an unconventional mRNA capping enzyme, namely GDP polyribonucleotidyltransferase, domain of the RABV L protein in mRNA capping and transcription initiation.
Collapse
Affiliation(s)
- Tomoaki Ogino
- Department of Molecular Biology and Microbiology, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA.
- Department of Inflammation and Immunity, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA.
| | - Todd J Green
- Department of Microbiology, School of Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
| |
Collapse
|
8
|
Hao H, Hao S, Chen H, Chen Z, Zhang Y, Wang J, Wang H, Zhang B, Qiu J, Deng F, Guan W. N6-methyladenosine modification and METTL3 modulate enterovirus 71 replication. Nucleic Acids Res 2019; 47:362-374. [PMID: 30364964 PMCID: PMC6326802 DOI: 10.1093/nar/gky1007] [Citation(s) in RCA: 127] [Impact Index Per Article: 25.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2018] [Revised: 10/09/2018] [Accepted: 10/11/2018] [Indexed: 12/11/2022] Open
Abstract
N6-methyladenosine (m6A) constitutes one of the most abundant internal RNA modifications and is critical for RNA metabolism and function. It has been previously reported that viral RNA contains internal m6A modifications; however, only recently the function of m6A modification in viral RNAs has been elucidated during infections of HIV, hepatitis C virus and Zika virus. In the present study, we found that enterovirus 71 (EV71) RNA undergoes m6A modification during viral infection, which alters the expression and localization of the methyltransferase and demethylase of m6A, and its binding proteins. Moreover, knockdown of m6A methyltransferase resulted in decreased EV71 replication, whereas knockdown of the demethylase had the opposite effect. Further study showed that the m6A binding proteins also participate in the regulation of viral replication. In particular, two m6A modification sites were identified in the viral genome, of which mutations resulted in decreased virus replication, suggesting that m6A modification plays an important role in EV71 replication. Notably, we found that METTL3 interacted with viral RNA-dependent RNA polymerase 3D and induced enhanced sumoylation and ubiquitination of the 3D polymerase that boosted viral replication. Taken together, our findings demonstrated that the host m6A modification complex interacts with viral proteins to modulate EV71 replication.
Collapse
Affiliation(s)
- Haojie Hao
- Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, Hubei 430071, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Sujuan Hao
- Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, Hubei 430071, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Honghe Chen
- Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, Hubei 430071, China
| | - Zhen Chen
- Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, Hubei 430071, China
| | - Yanfang Zhang
- Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, Hubei 430071, China
| | - Jun Wang
- Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, Hubei 430071, China
| | - Hanzhong Wang
- Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, Hubei 430071, China
| | - Bo Zhang
- Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, Hubei 430071, China
| | - Jianming Qiu
- Department of Microbiology, Molecular Genetics and Immunology, University of Kansas Medical Center, Kansas City, KS 66160, USA
| | - Fei Deng
- Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, Hubei 430071, China
| | - Wuxiang Guan
- Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, Hubei 430071, China
| |
Collapse
|
9
|
Epitranscriptomic regulation of viral replication. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2017; 1860:460-471. [PMID: 28219769 DOI: 10.1016/j.bbagrm.2017.02.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Revised: 02/10/2017] [Accepted: 02/10/2017] [Indexed: 12/11/2022]
Abstract
RNA plays central roles in biology and novel functions and regulation mechanisms are constantly emerging. To accomplish some of their functions within the cell, RNA molecules undergo hundreds of chemical modifications from which N6-methyladenosine (m6A), inosine (I), pseudouridine (ψ) and 5-methylcytosine (5mC) have been described in eukaryotic mRNA. Interestingly, the m6A modification was shown to be reversible, adding novel layers of regulation of gene expression through what is now recognized as epitranscriptomics. The development of molecular mapping strategies coupled to next generation sequencing allowed the identification of thousand of modified transcripts in different tissues and under different physiological conditions such as viral infections. As intracellular parasites, viruses are confronted to cellular RNA modifying enzymes and, as a consequence, viral RNA can be chemically modified at some stages of the replication cycle. This review focuses on the chemical modifications of viral RNA and the impact that these modifications have on viral gene expression and the output of infection. A special emphasis is given to m6A, which was recently shown to play important yet controversial roles in different steps of the HIV-1, HCV and ZIKV replication cycles.
Collapse
|
10
|
[The multifunctional RNA polymerase L protein of non-segmented negative strand RNA viruses catalyzes unique mRNA capping]. Uirusu 2016; 64:165-78. [PMID: 26437839 DOI: 10.2222/jsv.64.165] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Non-segmented negative strand RNA viruses belonging to the Mononegavirales order possess RNA-dependent RNA polymerase L proteins within viral particles. The L protein is a multifunctional enzyme catalyzing viral RNA synthesis and processing (i.e., mRNA capping, cap methylation, and polyadenylation). Using vesicular stomatitis virus (VSV) as a prototypic model virus, we have shown that the L protein catalyzes the unconventional mRNA capping reaction, which is strikingly different from the eukaryotic reaction. Furthermore, co-transcriptional pre-mRNA capping with the VSV L protein was found to be required for accurate stop?start transcription to synthesize full-length mRNAs in vitro and virus propagation in host cells. This article provides a review of historical and present studies leading to the elucidation of the molecular mechanism of VSV mRNA capping.
Collapse
|
11
|
Ogino T, Banerjee AK. An unconventional pathway of mRNA cap formation by vesiculoviruses. Virus Res 2011; 162:100-9. [PMID: 21945214 DOI: 10.1016/j.virusres.2011.09.012] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2011] [Revised: 09/07/2011] [Accepted: 09/08/2011] [Indexed: 01/11/2023]
Abstract
mRNAs of vesicular stomatitis virus (VSV), a prototype of nonsegmented negative strand (NNS) RNA viruses (e.g., rabies, measles, mumps, Ebola, and Borna disease viruses), possess the 5'-terminal cap structure identical to that of eukaryotic mRNAs, but the mechanism of mRNA cap formation is distinctly different from the latter. The elucidation of the unconventional capping of VSV mRNA remained elusive for three decades since the discovery of the cap structure in some viral and eukaryotic mRNAs in 1975. Only recently our biochemical studies revealed an unexpected strategy employed by vesiculoviruses (VSV and Chandipura virus, an emerging arbovirus) to generate the cap structure. This article summarizes the historical and current research that led to the discovery of the novel vesiculoviral mRNA capping reaction.
Collapse
Affiliation(s)
- Tomoaki Ogino
- Department of Molecular Genetics, Section of Virology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA.
| | | |
Collapse
|
12
|
A freeze frame view of vesicular stomatitis virus transcription defines a minimal length of RNA for 5' processing. PLoS Pathog 2011; 7:e1002073. [PMID: 21655110 PMCID: PMC3107219 DOI: 10.1371/journal.ppat.1002073] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2010] [Accepted: 04/04/2011] [Indexed: 11/25/2022] Open
Abstract
The RNA synthesis machinery of vesicular stomatitis virus (VSV) comprises the genomic RNA encapsidated by the viral nucleocapsid protein (N) and associated with the RNA dependent RNA polymerase, the viral components of which are a large protein (L) and an accessory phosphoprotein (P). The 241 kDa L protein contains all the enzymatic activities necessary for synthesis of the viral mRNAs, including capping, cap methylation and polyadenylation. Those RNA processing reactions are intimately coordinated with nucleotide polymerization such that failure to cap results in termination of transcription and failure to methylate can result in hyper polyadenylation. The mRNA processing reactions thus serve as a critical check point in viral RNA synthesis which may control the synthesis of incorrectly modified RNAs. Here, we report the length at which viral transcripts first gain access to the capping machinery during synthesis. By reconstitution of transcription in vitro with highly purified recombinant polymerase and engineered templates in which we omitted sites for incorporation of UTP, we found that transcripts that were 30-nucleotides in length were uncapped, whereas those that were 31-nucleotides in length contained a cap structure. The minimal RNA length required for mRNA cap addition was also sufficient for methylation since the 31-nucleotide long transcripts were methylated at both ribose-2′-O and guanine-N-7 positions. This work provides insights into the spatial relationship between the active sites for the RNA dependent RNA polymerase and polyribonucleotidyltransferase responsible for capping of the viral RNA. We combine the present findings with our recently described electron microscopic structure of the VSV polymerase and propose a model of how the spatial arrangement of the capping activities of L may influence nucleotide polymerization. Using a prototype of the nonsegmented negative strand RNA viruses, vesicular stomatitis virus, we probed the spatial relationship between the RNA dependent RNA polymerase and 5′ mRNA capping and methylation activities of the large polymerase protein. Because the 5′ mRNA processing reactions dramatically impact the nucleotide polymerization activity of the protein, they may function as a quality control step in viral transcription. We developed a means to stall transcription at precisely defined locations following initiation and analyzed the cap status of the stalled transcripts. We show that 30-nt transcripts are uncapped whereas those that are 31-nt long gain are capped and methylated at both guanine-N-7 and ribose-2′-O positions. Combined with our recent work that determined the molecular architecture of the VSV polymerase, this work reveals the spatial relationship within a functional polymerase complex of the polymerase domain and the 5′ mRNA processing domains of the L protein.
Collapse
|
13
|
Gupta KC, Roy P. Alternate capping mechanisms for transcription of spring viremia of carp virus: evidence for independent mRNA initiation. J Virol 2010; 33:292-303. [PMID: 16789187 PMCID: PMC288546 DOI: 10.1128/jvi.33.1.292-303.1980] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Two alternate mechanisms of mRNA capping for spring viremia of carp virus have been observed. Under normal reaction conditions, a ppG residue of the capping GTP is transferred to a pA moiety of the 5' termini of mRNA transcripts. However, in reaction conditions where GppNHp is used instead of GTP, an alternate capping mechanism occurs whereby a pG residue of the capping GTP is transferred to a ppA moiety of the transcripts. The first mechanism is identical to that described previously for vesicular stomatitis virus (G. Abraham, D. P. Rhodes, and A. K. Banerjee, Nature [London] 255:37-40, 1975; A. K. Banerjee, S. A. Moyer, and D. P. Rhodes, Virology 61:547-558, 1974), and thus appears to be a conserved function during the evolution of rhabdoviruses. The alternate mechanism of capping indicates not only that capping can take place by two procedures, but also that the substrate termini have di- or triphosphate 5' ends, indicating that they are probably independently initiated. An analog of ATP, AppNHp, has been found to completely inhibit the initiation of transcription by spring viremia of carp virus, suggesting that a cleavage between the beta and gamma phosphates of ATP is essential for the initiation of transcription. However, in the presence of GppNHp, uncapped (ppAp and pppAp), capped (GpppAp), and capped methylated (m7GpppAmpAp and GpppAmpAp) transcripts are detected. Size analyses of oligodeoxythymidylic acid-cellulose-bound transcripts resolved by formamide gel electrophoresis demonstrated that full-size mRNA transcripts are synthesized as well as larger RNA species. The presence of GppNHp and S-adenosylhomocysteine in reaction mixtures did not have any effect on the type of unmethylated transcription products. Our results favor a transcription model postulated previously (D. H. L. Bishop, in H. Fraenkel-Conrat and R. R. Wagner, ed., Comprehensive Virology, vol. 10, Plenum Press, New York, 1977; D. H. L. Bishop and A. Flamand, in D. C. Burke and W. C. Russell, ed., Control Processes in Virus Multiplication, Cambridge University Press, Cambridge, 1975; D. H. L. Bishop and M. S. Smith, in D. Nayak, ed., The Molecular Biology of Animal Viruses, Marcel Dekker, New York, 1977; P. Roy and D. H. L. Bishop, J. Virol. 11:487-501, 1973) in which mRNA synthesis is initiated independently; they do not support a model for transcripts being synthesized by plus-strand cleavage (A. K. Banerjee, G. Abraham, and R. J. Colonno, J. Gen. Virol. 34:1-8, 1977; A. K. Banerjee, R. J. Colonno, D. Testa, and M. T. Franze-Fernandez, in B. M. J. Mahy and R. D. Barry, ed., Negative Strand Viruses and the Host Cells, Academic Press, London, 1978).
Collapse
Affiliation(s)
- K C Gupta
- Departments of Microbiology and Public Health, University of Alabama in Birmingham, Birmingham, Alabama 35294
| | | |
Collapse
|
14
|
New mRNAs are preferentially translated during vesicular stomatitis virus infection. J Virol 2007; 82:2286-94. [PMID: 18094194 DOI: 10.1128/jvi.01761-07] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
During vesicular stomatitis virus (VSV) infection, host protein synthesis is inhibited, while synthesis of viral proteins increases. VSV infection causes inhibition of host transcription and RNA transport. Therefore, most host mRNAs in the cytoplasm of infected cells were synthesized before infection. However, viral mRNAs are synthesized throughout infection and are newer than preexisting host mRNAs. To determine if the timing of appearance of mRNAs in the cytoplasm affected their translation during VSV infection, we transfected reporter mRNAs into cells at various times relative to the time of infection and measured their rate of translation in mock- and VSV-infected cells. We found that translation of mRNAs transfected during infection was not inhibited but that translation of mRNAs transfected prior to infection was inhibited during VSV infection. Based on these data, we conclude that the timing of viral mRNA appearance in the cytoplasm is responsible, at least in part, for the preferential translation of VSV mRNAs. A time course measuring translation efficiencies of viral and host mRNAs showed that the translation efficiencies of viral mRNAs increased between 4 and 8 h postinfection, while translation efficiencies of host mRNAs decreased. The increased translation efficiency of viral mRNAs occurred in cells infected with an M protein mutant virus that is defective in host shutoff, demonstrating that the enhanced translation of viral mRNA is genetically separable from inhibition of translation of host mRNA.
Collapse
|
15
|
Whitlow ZW, Connor JH, Lyles DS. Preferential translation of vesicular stomatitis virus mRNAs is conferred by transcription from the viral genome. J Virol 2006; 80:11733-42. [PMID: 17005665 PMCID: PMC1642595 DOI: 10.1128/jvi.00971-06] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Host protein synthesis is inhibited in cells infected with vesicular stomatitis virus (VSV). It has been proposed that viral mRNAs are subjected to the same inhibition but are predominantly translated because of their abundance. To compare translation efficiencies of viral and host mRNAs during infection, we used an enhanced green fluorescent protein (EGFP) reporter expressed from a recombinant virus or from the host nucleus in stably transfected cells. Translation efficiency of host-derived EGFP mRNA was reduced more than threefold at eight hours postinfection, while viral-derived mRNA was translated around sevenfold more efficiently than host-derived EGFP mRNA in VSV-infected cells. To test whether mRNAs transcribed in the cytoplasm are resistant to shutoff of translation during VSV infection, HeLa cells were infected with a recombinant simian virus 5 (rSV5) that expressed GFP. Cells were then superinfected with VSV or mock superinfected. GFP mRNA transcribed by rSV5 was not resistant to translation inhibition during superinfection with VSV, indicating that transcription in the cytoplasm is not sufficient for preventing translation inhibition. To determine if cis-acting sequences in untranslated regions (UTRs) were involved in preferential translation of VSV mRNAs, we constructed EGFP reporters with VSV or control UTRs and measured the translation efficiency in mock-infected and VSV-infected cells. The presence of VSV UTRs did not affect mRNA translation efficiency in mock- or VSV-infected cells, indicating that VSV mRNAs do not contain cis-acting sequences that influence translation. However, we found that when EGFP mRNAs transcribed by VSV or by the host were translated in vitro, VSV-derived EGFP mRNA was translated 22 times more efficiently than host-derived EGFP mRNA. This indicated that VSV mRNAs do contain cis-acting structural elements (that are not sequence based), which enhance translation efficiency of viral mRNAs.
Collapse
Affiliation(s)
- Zackary W Whitlow
- Department of Biochemistry, Wake Forest University School of Medicine, Winston-Salem, NC 27157, USA.
| | | | | |
Collapse
|
16
|
Li J, Wang JT, Whelan SPJ. A unique strategy for mRNA cap methylation used by vesicular stomatitis virus. Proc Natl Acad Sci U S A 2006; 103:8493-8. [PMID: 16709677 PMCID: PMC1482520 DOI: 10.1073/pnas.0509821103] [Citation(s) in RCA: 118] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Nonsegmented negative-sense (nsNS) RNA viruses typically replicate within the host cell cytoplasm and do not have access to the host mRNA capping machinery. These viruses have evolved a unique mechanism for mRNA cap formation in that the guanylyltransferase transfers GDP rather than GMP onto the 5' end of the RNA. Working with vesicular stomatitis virus (VSV), a prototype nsNS RNA virus, we now provide genetic and biochemical evidence that its mRNA cap methylase activities are also unique. Using recombinant VSV, we determined the function in mRNA cap methylation of a predicted binding site in the polymerase for the methyl donor, S-adenosyl-l-methionine. We found that amino acid substitutions to this site disrupted methylation at the guanine-N-7 (G-N-7) position or at both the G-N-7 and ribose-2'-O (2'-O) positions of the mRNA cap. These studies provide genetic evidence that the two methylase activities share an S-adenosyl-l-methionine-binding site and show that, in contrast to other cap methylation reactions, methylation of the G-N-7 position is not required for 2'-O methylation. These findings suggest that VSV evolved an unusual strategy of mRNA cap methylation that may be shared by other nsNS RNA viruses.
Collapse
Affiliation(s)
- Jianrong Li
- Department of Microbiology and Molecular Genetics, Harvard Medical School, 200 Longwood Avenue, Boston, MA 02115
| | - Jennifer T. Wang
- Department of Microbiology and Molecular Genetics, Harvard Medical School, 200 Longwood Avenue, Boston, MA 02115
| | - Sean P. J. Whelan
- Department of Microbiology and Molecular Genetics, Harvard Medical School, 200 Longwood Avenue, Boston, MA 02115
- *To whom correspondence should be addressed. E-mail:
| |
Collapse
|
17
|
Li J, Fontaine-Rodriguez EC, Whelan SPJ. Amino acid residues within conserved domain VI of the vesicular stomatitis virus large polymerase protein essential for mRNA cap methyltransferase activity. J Virol 2005; 79:13373-84. [PMID: 16227259 PMCID: PMC1262600 DOI: 10.1128/jvi.79.21.13373-13384.2005] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
During mRNA synthesis, the polymerase of vesicular stomatitis virus (VSV) copies the genomic RNA to produce five capped and polyadenylated mRNAs with the 5'-terminal structure 7mGpppA(m)pApCpApGpNpNpApUpCp. The 5' mRNA processing events are poorly understood but presumably require triphosphatase, guanylyltransferase, [guanine-N-7]- and [ribose-2'-O]-methyltransferase (MTase) activities. Consistent with a role in mRNA methylation, conserved domain VI of the 241-kDa large (L) polymerase protein shares sequence homology with a bacterial [ribose-2'-O]-MTase, FtsJ/RrmJ. In this report, we generated six L gene mutations to test this homology. Individual substitutions to the predicted MTase active-site residues K1651, D1762, K1795, and E1833 yielded viruses with pinpoint plaque morphologies and 10- to 1,000-fold replication defects in single-step growth assays. Consistent with these defects, viral RNA and protein synthesis was diminished. In contrast, alteration of residue G1674 predicted to bind the methyl donor S-adenosylmethionine did not significantly perturb viral growth and gene expression. Analysis of the mRNA cap structure revealed that alterations to the predicted active site residues decreased [guanine-N-7]- and [ribose-2'-O]-MTase activity below the limit of detection of our assay. In contrast, the alanine substitution at G1674 had no apparent consequence. These data show that the predicted MTase active-site residues K1651, D1762, K1795, and E1833 within domain VI of the VSV L protein are essential for mRNA cap methylation. A model of mRNA processing consistent with these data is presented.
Collapse
Affiliation(s)
- Jianrong Li
- HMS-Microbiology, 200 Longwood Avenue, Boston, MA 02115, USA
| | | | | |
Collapse
|
18
|
Whelan SPJ, Barr JN, Wertz GW. Transcription and replication of nonsegmented negative-strand RNA viruses. Curr Top Microbiol Immunol 2004; 283:61-119. [PMID: 15298168 DOI: 10.1007/978-3-662-06099-5_3] [Citation(s) in RCA: 178] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The nonsegmented negative-strand (NNS) RNA viruses of the order Mononegavirales include a wide variety of human, animal, and plant pathogens. The NNS RNA genomes of these viruses are templates for two distinct RNA synthetic processes: transcription to generate mRNAs and replication of the genome via production of a positive-sense antigenome that acts as template to generate progeny negative-strand genomes. The four virus families within the Mononegavirales all express the information encoded in their genomes by transcription of discrete subgenomic mRNAs. The key feature of transcriptional control in the NNS RNA viruses is entry of the virus-encoded RNA-dependent RNA polymerase at a single 3' proximal site followed by obligatory sequential transcription of the linear array of genes. Levels of gene expression are primarily regulated by position of each gene relative to the single promoter and also by cis-acting sequences located at the beginning and end of each gene and at the intergenic junctions. Obligatory sequential transcription dictates that termination of each upstream gene is required for initiation of downstream genes. Therefore, termination is a means to regulate expression of individual genes within the framework of a single transcriptional promoter. By engineering either whole virus genomes or subgenomic replicon derivatives, elements important for signaling transcript initiation, 5' end modification, 3' end polyadenylation, and transcription termination have been identified. Although the diverse families of NNS RNA virus use different sequences to control these processes, transcriptional termination is a common theme in controlling gene expression and overall transcriptional regulation is key in controlling the outcome of viral infection. The latest models for control of replication and transcription are discussed.
Collapse
Affiliation(s)
- S P J Whelan
- Department of Microbiology and Molecular Genetics, Harvard Medical School, 200 Longwood Ave, Boston, MA 02115, USA
| | | | | |
Collapse
|
19
|
Barr JN, Whelan SPJ, Wertz GW. Transcriptional control of the RNA-dependent RNA polymerase of vesicular stomatitis virus. BIOCHIMICA ET BIOPHYSICA ACTA 2002; 1577:337-53. [PMID: 12213662 DOI: 10.1016/s0167-4781(02)00462-1] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The nonsegmented negative strand (NNS) RNA viruses include some of the mosr problematic human, animal and plant pathogens extant: for example, rabies virus, Ebola virus, respiratory syncytial virus, the parainfluenza viruses, measles and infectious hemapoietic necrosis virus. The key feature of transcriptional control in the NNS RNA viruses is polymerase entry at a single 3' proximal site followed by obligatory sequential transcription of the linear array of genes. The levels of gene expression are primarily regulated by their position on the genome. The promoter proximal gene is transcribed in greatest abundance and each successive downstream gene is synthesized in progressively lower amounts due to attenuation of transcription at each successive gene junction. In addition, NNS RNA virus gene expression is regulated by cis-acting sequences that reside at the beginning and end of each gene and the intergenic junctions. Using vesicular stomatitis virus (VSV), the prototypic NNS, many of these control elements have been identified.The signals for transcription initiation and 5' end modification and for 3' end polyadenylation and termination have been elucidated. The sequences that determine the ability of the polymerase to slip on the template to generate polyadenylate have been identified and polyadenylation has been shown to be template dependent and integral to the termination process. Transcriptional termination is a key element in control of gene expression of the negative strand RNA viruses and a means by which expression of individual genes may be silenced or regulated within the framework of a single transcriptional promoter. In addition, the fundamental question of the site of entry of the polymerase during transcription has been reexamined and our understanding of the process altered and updated. The ability to engineer changes into infectious viruses has confirmed the action of these elements and as a consequence, it has been shown that transcriptional control is key to controlling the outcome of a viral infection. Finally, the principles of transcriptional regulation have been utilized to develop a new paradigm for systematic attenuation of virulence to develop live attenuated viral vaccines.
Collapse
Affiliation(s)
- John N Barr
- Department of Microbiology, BBRB 17, Room 366, University of Alabama School of Medicine, 845 19th Street S., Birmingham, AL 35294, USA
| | | | | |
Collapse
|
20
|
Stillman EA, Whitt MA. Transcript initiation and 5'-end modifications are separable events during vesicular stomatitis virus transcription. J Virol 1999; 73:7199-209. [PMID: 10438807 PMCID: PMC104244 DOI: 10.1128/jvi.73.9.7199-7209.1999] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In this report we describe a novel, bipartite vesicular stomatitis virus (VSV) replication system which was used to study the effect of mutations in the transcription start sequence on transcript initiation and 5'-mRNA modifications. The bipartite replication system consisted of two genomic RNAs, one of which (VSVDeltaG) was a recombinant VSV genome with the G gene deleted and the other (GFC) contained the G gene and two non-VSV reporter genes (green fluorescent protein [GFP] and chloramphenicol acetyltransferase [CAT]). Coinfection of cells with these two components resulted in high-level virus production and gave titers similar to that from wild-type-VSV-infected cells. Mutations were introduced within the first 3 nucleotides of the transcription start sequence of the third gene (CAT) of GFC. The effects of these changes on the synthesis and accumulation of CAT transcripts during in vivo transcription (e.g., in infected cells), and during in vitro transcription were determined. As we had reported previously (E. A. Stillman and M. A. Whitt, J. Virol. 71:2127-2137, 1997), changing the first and third nucleotides (NT-1 and NT-3) reduced CAT transcript levels in vivo to near undetectable levels. Similarly, changing NT-2 to a purine also resulted in the detection of very small amounts of CAT mRNA from infected cells. In contrast to the results in vivo, the NT-1C mutant and all of the second-position mutants produced near-wild-type amounts of CAT mRNA in the in vitro system, indicating that the mutations did not prevent transcript initiation per se but, rather, generated transcripts that were unstable in vivo. Oligo (dT) selection and Northern blot analysis revealed that the transcripts produced from these mutants did not contain a poly(A)(+) tail and were truncated, ranging in size from 40 to 200 nucleotides. Immunoprecipitation analysis of cDNA-RNA hybrids with an antibody that recognizes trimethylguanosine revealed that the truncated mutant transcripts were not properly modified at the 5' end, indicating the transcripts either were not capped or were not methylated. This is the first demonstration that transcript initiation and capping/methylation are separable events during VSV transcription. A model is proposed in which polymerase processivity is linked to proper 5'-end modification. The model suggests that a proofreading mechanism exists for VSV and possibly other nonsegmented minus-strand RNA viruses, whereby if some transcripts do not become capped during transcription in a normal infection, a signal is transduced such that the polymerase undergoes abortive elongation and the defective transcript is terminated prematurely and subsequently degraded.
Collapse
Affiliation(s)
- E A Stillman
- Department of Microbiology and Immunology, University of Tennessee-Memphis, Memphis, Tennessee 38163, USA
| | | |
Collapse
|
21
|
Stillman EA, Whitt MA. The length and sequence composition of vesicular stomatitis virus intergenic regions affect mRNA levels and the site of transcript initiation. J Virol 1998; 72:5565-72. [PMID: 9621014 PMCID: PMC110208 DOI: 10.1128/jvi.72.7.5565-5572.1998] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
In this study, we used a dicistronic vesicular stomatitis virus (VSV) minigenome to investigate the effects of either single or multiple nucleotide insertions placed immediately after the nontranscribed intergenic dinucleotide of the M gene on VSV transcription. Both Northern blot and primer extension analysis showed that the polymerase responded to the inserted nucleotides in a sequence-specific manner such that some insertions had no effect on mRNA synthesis from the downstream G gene, nor on the site of transcript initiation, whereas other insertions resulted in dramatic reductions in transcript accumulation. Some of these transcripts were initiated at the wild-type site, while others initiated within the inserted sequence. We also examined the transcriptional events that occurred when a natural, 21-nucleotide intergenic region located between the G and L genes from the New Jersey (NJ) serotype of VSV was inserted into the minigenome gene junction. In contrast to the normal 25 to 30% attenuation observed for downstream transcription at gene junctions containing the typical dinucleotide (3'-GA-5') intergenic region, the NJ variant showed greater than 75% attenuation at the gene junction. In addition, the polymerase initiated transcription at two major start sites, one of which was located within the intergenic sequence. Collectively, these data suggest that the polymerase "samples" the intergenic sequences following polyadenylation and termination of the upstream transcript by scanning until an appropriate start site is found. One implication of a scanning polymerase is that the polymerase presumably switches states from a processive elongation mode to a stuttering mode for polyadenylation to one in which no transcription occurs, before it reinitiates at the downstream gene. Our data support the hypothesis that sequences surrounding the intergenic region modulate these events such that appropriate amounts of each mRNA are synthesized.
Collapse
Affiliation(s)
- E A Stillman
- Department of Microbiology and Immunology, University of Tennessee, Memphis, Memphis, Tennessee 38163, USA
| | | |
Collapse
|
22
|
Stillman EA, Whitt MA. Mutational analyses of the intergenic dinucleotide and the transcriptional start sequence of vesicular stomatitis virus (VSV) define sequences required for efficient termination and initiation of VSV transcripts. J Virol 1997; 71:2127-37. [PMID: 9032346 PMCID: PMC191313 DOI: 10.1128/jvi.71.3.2127-2137.1997] [Citation(s) in RCA: 83] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
We have used dicistronic vesicular stomatitis virus (VSV) minigenomes to dissect the functional importance of the nontranscribed intergenic dinucleotide and the conserved transcription start sequence found at the beginning of all VSV genes. The minigenomes were generated entirely from cDNA and contained the G and M protein genes, flanked by the leader and trailer regions from the Indiana serotype of VSV. All mutations were made either within the nontranscribed M-G intergenic dinucleotide or within the transcription start sequence of the downstream G gene. Immunofluorescence microscopy and immunoprecipitation analysis of the mutated minigenomes indicated that the first three nucleotides of the transcriptional start sequence are the most critical for efficient VSV gene expression, whereas the nontranscribed, intergenic dinucleotide and the other conserved nucleotides found at the 5' mRNA start sequence can tolerate significant sequence variability without affecting G protein production. RNA analysis indicated that nucleotide changes in the transcriptional start sequence which resulted in reduced G protein expression correlated with the amount of transcript present. Therefore, this conserved sequence appears to be required for efficient transcript initiation following polyadenylation of the upstream mRNA. While the minimum sequence for efficient transcription (3'-UYGnn-5') is similar to that of other rhabdoviruses, it is not homologous to the start sites for viruses from the Paramyxoviridae or Filoviridae families. Using Northern blot analysis, we also found that some nucleotide changes in the nontranscribed intergenic region resulted in higher levels of read-through transcription. Therefore, the nontranscribed intergenic dinucleotide plays a role in transcript termination.
Collapse
Affiliation(s)
- E A Stillman
- Department of Microbiology and Immunology, University of Tennessee, Memphis 38163, USA
| | | |
Collapse
|
23
|
|
24
|
Oostergetel GT, Wall JS, Hainfeld JF, Boublik M. Quantitative structural analysis of eukaryotic ribosomal RNA by scanning transmission electron microscopy. Proc Natl Acad Sci U S A 1985; 82:5598-602. [PMID: 3862084 PMCID: PMC390598 DOI: 10.1073/pnas.82.17.5598] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
The conformation of 28S ribosomal RNA isolated from baby hamster kidney cells was studied by scanning transmission electron microscopy (STEM) and circular dichroic spectroscopy to establish the conditions under which STEM images of unstained freeze-dried rRNA are a meaningful representation of the conformation of rRNA in solution. We have determined the conformation of 28S rRNA under various buffer conditions, the molecular mass, the mass distribution, and the number of polynucleotide strands within the individual molecules, and the apparent radii of gyration. The 28S rRNA molecule is highly extended in water and becomes compact with increasing ionic strength. However, even in the "reconstitution buffer" (30 mM Tris/HCl/20 mM MgCl2/360 mM KCl, pH 7.6) the compactness does not reach a state in which the rRNA molecule appears structurally similar to the 60S ribosomal subunit. Our approach has a broad application in high-resolution structural studies of nucleic acids and nucleic acid-protein interactions.
Collapse
|
25
|
Horikami SM, De Ferra F, Moyer SA. Characterization of the infections of permissive and nonpermissive cells by host range mutants of vesicular stomatitis virus defective in RNA methylation. Virology 1984; 138:1-15. [PMID: 6093352 DOI: 10.1016/0042-6822(84)90142-9] [Citation(s) in RCA: 35] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Two host range mutants of VSV, hr 1 and hr 8, which, unlike the wild-type virus, have a mRNA methylation defect and direct the in vitro synthesis of full-length capped but unmethylated viral mRNAs have been described previously (S.M. Horikami and S.A. Moyer, 1982, Proc. Natl, Acad. Sci. USA 79, 7694-7698). It is shown that the in vivo nonpermissive infection of HEp-2 cells by either of these two mutants is characterized by the reduced synthesis of full-length mRNAs at levels characteristic of primary transcription and the total lack of synthesis of genome-length RNA. The VSV mRNAs synthesized by either mutant in HEp-2 cells are not translated either in vivo or in vitro in mRNA-dependent rabbit reticulocyte lysates. Subsequent isolation and analysis of the mRNAs from infected HEp-2 cells has shown that the 5' termini of the messages contain a cap structure which is guanylylated, but unmethylated (GpppA), a finding that might account for the lack of translatability. Hence these mutants are unable to properly methylate mRNAs whether they are synthesized in vitro or in vivo within nonpermissively infected cells. It is also shown that unlike hr 1, the undermethylation of mRNA synthesized by hr 8 is partially reversible by the addition of high levels of AdoMet in vitro. It is interesting to note, therefore, that permissive baby hamster kidney (BHK) cells have a 10-fold higher level of endogenous AdoMet than the nonpermissive HEp-2 cells. Unlike singly infected cells, the coinfection of HEp-2 cells with either hr mutant and a poxvirus yields a permissive infection for these two host range mutants. Analysis of the VSV mRNAs produced in vivo under the conditions of rescue reveals the presence of fully methylated caps (7mGppp(m)Am), suggesting that poxvirus may rescue the mutants by converting the VSV mRNAs to a translationally active form due to methylation by the cytoplasmic poxvirus mRNA methyltransferase enzymes. Both mutants are, however, able to grow normally in permissive BHK cells. An analysis of the translationally active mRNAs from infected permissive cells shows the presence primarily of a 5'-monomethylated cap, 7mGpppA. Finally, we have examined the nonpermissive infections of two other host range mutants of VSV (hr 5 and hr 7). Unlike mutants hr 1 and hr 8 described above, these two mutants synthesize mRNA in HEp-2 cells which is translated both in vivo and in vitro.
Collapse
|
26
|
Tsurumi T, Aoki H, Nishiyama Y, Shibata M, Maeno K, Seo H. Effect of high salt treatment on influenza B viral protein synthesis in MDCK cells. Microbiol Immunol 1983; 27:519-29. [PMID: 6195511 DOI: 10.1111/j.1348-0421.1983.tb00613.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Based on the information that high salt inhibits the initiation of cellular mRNA translation which depends on the function of the 5'-terminal structure of mRNA, we compared the effect of high salt on translation of host cellular mRNAs and influenza viral mRNAs, both of which are of 5'-terminal structure. Brief exposure of influenza B virus-infected MDCK cells to high salt medium resulted in a dose-dependent inhibition of viral polypeptide synthesis as well as of cellular polypeptide synthesis, but it had less effect on synthesis of viral polypeptides, particularly nonstructural protein (NS). Under these conditions the Na+ content of the infected cells was significantly increased. A similar salt effect on in vitro translation of viral and cellular mRNAs extracted from infected cells was also observed. There was no significant difference in sensitivity to hypertonic block of in vivo translation of influenza viral mRNAs and vesicular stomatitis virus mRNAs, the latter of which possess a virus-directed structure at the 5'-terminus.
Collapse
|
27
|
Increase in S-adenosylhomocysteine concentration in interferon-treated HeLa cells and inhibition of methylation of vesicular stomatitis virus mRNA. J Biol Chem 1983. [DOI: 10.1016/s0021-9258(18)32894-1] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
|
28
|
Salas ML, Kuznar J, Viñuela E. Polyadenylation, methylation, and capping of the RNA synthesized in vitro by African swine fever virus. Virology 1981; 113:484-91. [PMID: 6168100 DOI: 10.1016/0042-6822(81)90176-8] [Citation(s) in RCA: 68] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
|
29
|
de Ferra F, Baglioni C. Viral messenger RNA unmethylated in the 5'-terminal guanosine in interferon-treated HeLa cells infected with vesicular stomatitis virus. Virology 1981; 112:426-35. [PMID: 6167059 DOI: 10.1016/0042-6822(81)90290-7] [Citation(s) in RCA: 33] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
|
30
|
Moyer SA. Alteration of the 5' terminal caps of the mRNAs of vesicular stomatitis virus by cycloleucine in vivo. Virology 1981; 112:157-68. [PMID: 6264679 DOI: 10.1016/0042-6822(81)90621-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
|
31
|
|
32
|
|
33
|
Grubman MJ, Bachrach HL. Isolation of foot-and-mouth disease virus messenger RNA from membrane-bound polyribosomes and characterization of its 5' and 3' termini. Virology 1979; 98:466-70. [PMID: 228483 DOI: 10.1016/0042-6822(79)90570-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
|
34
|
Moyer SA, Holmes KS. The specific inhibition of vesicular stomatitis virus replication by toyocamycin. Virology 1979; 98:99-107. [PMID: 225872 DOI: 10.1016/0042-6822(79)90528-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
|
35
|
|
36
|
Caboche M, La Bonnardiere C. Vesicular stomatitis virus mRNA methylation in vivo: effect of cycloleucine, an inhibitor of S-adenosylmethionine biosynthesis, on viral transcription and translation. Virology 1979; 93:547-57. [PMID: 222056 DOI: 10.1016/0042-6822(79)90257-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
|
37
|
Moyer SA, Gatchell SH. Intracellular events in the replication of defective interfering particles of vesicular stomatitis virus. Virology 1979; 92:168-79. [PMID: 217161 DOI: 10.1016/0042-6822(79)90222-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
|
38
|
|
39
|
HeLa cell RNA (2‘-O-methyladenosine-N6-)-methyltransferase specific for the capped 5‘-end of messenger RNA. J Biol Chem 1978. [DOI: 10.1016/s0021-9258(17)34652-5] [Citation(s) in RCA: 67] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
|
40
|
Levis R, Penman S. 5'-terminal structures of poly(A)+ cytoplasmic messenger RNA and of poly(A)+ and poly(A)- heterogeneous nuclear RNA of cells of the dipteran Drosophila melanogaster. J Mol Biol 1978; 120:487-515. [PMID: 418182 DOI: 10.1016/0022-2836(78)90350-9] [Citation(s) in RCA: 77] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
|
41
|
Bartkoski MJ, Roizman B. Regulation of herpesvirus macromolecular synthesis. VII. Inhibition of internal methylation of mRNA late in infection. Virology 1978; 85:146-56. [PMID: 205998 DOI: 10.1016/0042-6822(78)90419-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
|
42
|
|
43
|
|
44
|
Boone RF, Moss B. Methylated 5'-terminal sequences of vaccinia virus mRNA species made in vivo at early and late times after infection. Virology 1977; 79:67-80. [PMID: 867823 DOI: 10.1016/0042-6822(77)90335-x] [Citation(s) in RCA: 53] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
|
45
|
|
46
|
Rhodes DP, Reddy DV, MacLeod R, Black LM, Banerjee AK. In vitro synthesis of RNA containing 5'-terminal structure 7nG(5')ppp(5')Apm... by purified wound tumor virus. Virology 1977; 76:554-9. [PMID: 841848 DOI: 10.1016/0042-6822(77)90237-9] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
|
47
|
Desrosiers RC, Sen GC, Lengyel P. Difference in 5' terminal structure between the mRNA and the double-stranded virion RNA of reovirus. Biochem Biophys Res Commun 1976; 73:32-9. [PMID: 999700 DOI: 10.1016/0006-291x(76)90493-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
|