1
|
Ritsch I, Lehmann E, Emmanouilidis L, Yulikov M, Allain F, Jeschke G. Phase Separation of Heterogeneous Nuclear Ribonucleoprotein A1 upon Specific RNA-Binding Observed by Magnetic Resonance. Angew Chem Int Ed Engl 2022; 61:e202204311. [PMID: 35866309 PMCID: PMC9804974 DOI: 10.1002/anie.202204311] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2022] [Indexed: 01/09/2023]
Abstract
Interaction of heterogeneous nuclear ribonucleoprotein A1 (hnRNP A1) with specific single-stranded RNA and its relation to liquid-liquid phase separation (LLPS) were studied in vitro by magnetic resonance based on site-directed spin labelling. An ensemble model of dispersed hnRNP A1 in the absence of RNA was derived from distance distributions between spin labelled sites and small angle X-ray scattering. This model revealed a compact state of the low-complexity domain and its interaction with the RNA recognition motifs. Paramagnetic relaxation enhancement NMR spectroscopy confirmed this interaction. Addition of RNA to dispersed hnRNP A1 induced liquid-droplet formation. Such LLPS depended on RNA concentration and sequence, with continuous wave EPR spectroscopy showing an influence of RNA point mutations on local protein dynamics. We propose that an interplay of sequence-specific RNA binding and LLPS contributes to regulation of specific RNA segregation during stress response.
Collapse
Affiliation(s)
- Irina Ritsch
- Laboratory of Physical ChemistryDepartment of Chemistry and Applied BioscienceETH ZurichVladimir-Prelog-Weg 28093ZürichSwitzerland
| | - Elisabeth Lehmann
- Institute of BiochemistryDepartment of BiologyETH ZurichHönggerbergring 648093ZürichSwitzerland
| | - Leonidas Emmanouilidis
- Institute of BiochemistryDepartment of BiologyETH ZurichHönggerbergring 648093ZürichSwitzerland
| | - Maxim Yulikov
- Laboratory of Physical ChemistryDepartment of Chemistry and Applied BioscienceETH ZurichVladimir-Prelog-Weg 28093ZürichSwitzerland
| | - Frédéric Allain
- Institute of BiochemistryDepartment of BiologyETH ZurichHönggerbergring 648093ZürichSwitzerland
| | - Gunnar Jeschke
- Laboratory of Physical ChemistryDepartment of Chemistry and Applied BioscienceETH ZurichVladimir-Prelog-Weg 28093ZürichSwitzerland
| |
Collapse
|
2
|
Ritsch I, Lehmann E, Emmanouilidis L, Yulikov M, Allain F, Jeschke G. Phase Separation of Heterogeneous Nuclear Ribonucleoprotein A1 upon Specific RNA‐Binding Observed by Magnetic Resonance. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202204311] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Irina Ritsch
- ETH Zürich: Eidgenossische Technische Hochschule Zurich Chemistry and Applied Biosciences Valdimir-Prelog-Weg 2 8093 Zurich SWITZERLAND
| | - Elisabeth Lehmann
- ETH Zürich: Eidgenossische Technische Hochschule Zurich Biologie Hönggerbergring 64 8093 Zurich SWITZERLAND
| | - Leonidas Emmanouilidis
- ETH Zürich: Eidgenossische Technische Hochschule Zurich Biologie Hönggerbergring 64 8093 Zurich SWITZERLAND
| | - Maxim Yulikov
- ETH Zürich: Eidgenossische Technische Hochschule Zurich Chemistry and Applied Biosciences 8093 Zurich SWITZERLAND
| | - Frédéric Allain
- ETH Zürich: Eidgenossische Technische Hochschule Zurich Biologie Hönggerbergring 64 8093 Zurich SWITZERLAND
| | - Gunnar Jeschke
- ETH Zürich: Eidgenossische Technische Hochschule Zurich Chemistry and Applied Biosciences Vlaldimir-Prelog-Weg 2ETH Hönggerberg 8093 Zürich SWITZERLAND
| |
Collapse
|
3
|
Abstract
After human immunodeficiency virus type 1 (HIV-1) was identified in the early 1980s, intensive work began to understand the molecular basis of HIV-1 gene expression. Subgenomic HIV-1 RNA regions, spread throughout the viral genome, were described to have a negative impact on the nuclear export of some viral transcripts. Those studies revealed an intrinsic RNA code as a new form of nuclear export regulation. Since such regulatory regions were later also identified in other viruses, as well as in cellular genes, it can be assumed that, during evolution, viruses took advantage of them to achieve more sophisticated replication mechanisms. Here, we review HIV-1 cis-acting repressive sequences that have been identified, and we discuss their possible underlying mechanisms and importance. Additionally, we show how current bioinformatic tools might allow more predictive approaches to identify and investigate them.
Collapse
|
4
|
Advanced approaches for elucidating structures of large RNAs using NMR spectroscopy and complementary methods. Methods 2020; 183:93-107. [DOI: 10.1016/j.ymeth.2020.01.009] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Revised: 11/11/2019] [Accepted: 01/16/2020] [Indexed: 11/23/2022] Open
|
5
|
Li B, Cao Y, Westhof E, Miao Z. Advances in RNA 3D Structure Modeling Using Experimental Data. Front Genet 2020; 11:574485. [PMID: 33193680 PMCID: PMC7649352 DOI: 10.3389/fgene.2020.574485] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Accepted: 09/02/2020] [Indexed: 12/26/2022] Open
Abstract
RNA is a unique bio-macromolecule that can both record genetic information and perform biological functions in a variety of molecular processes, including transcription, splicing, translation, and even regulating protein function. RNAs adopt specific three-dimensional conformations to enable their functions. Experimental determination of high-resolution RNA structures using x-ray crystallography is both laborious and demands expertise, thus, hindering our comprehension of RNA structural biology. The computational modeling of RNA structure was a milestone in the birth of bioinformatics. Although computational modeling has been greatly improved over the last decade showing many successful cases, the accuracy of such computational modeling is not only length-dependent but also varies according to the complexity of the structure. To increase credibility, various experimental data were integrated into computational modeling. In this review, we summarize the experiments that can be integrated into RNA structure modeling as well as the computational methods based on these experimental data. We also demonstrate how computational modeling can help the experimental determination of RNA structure. We highlight the recent advances in computational modeling which can offer reliable structure models using high-throughput experimental data.
Collapse
Affiliation(s)
- Bing Li
- Center of Growth, Metabolism and Aging, Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, China
| | - Yang Cao
- Center of Growth, Metabolism and Aging, Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, China
| | - Eric Westhof
- Architecture et Réactivité de l’ARN, Institut de Biologie Moléculaire et Cellulaire du CNRS, Université de Strasbourg, Strasbourg, France
| | - Zhichao Miao
- Translational Research Institute of Brain and Brain-Like Intelligence, Department of Anesthesiology, Shanghai Fourth People’s Hospital Affiliated to Tongji University School of Medicine, Shanghai, China
- Newcastle Fibrosis Research Group, Institute of Cellular Medicine, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, United Kingdom
- European Molecular Biology Laboratory, European Bioinformatics Institute (EMBL-EBI), Cambridge, United Kingdom
| |
Collapse
|
6
|
HIV-1 Lethality and Loss of Env Protein Expression Induced by Single Synonymous Substitutions in the Virus Genome Intronic-Splicing Silencer. J Virol 2020; 94:JVI.01108-20. [PMID: 32817222 DOI: 10.1128/jvi.01108-20] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Accepted: 08/06/2020] [Indexed: 01/13/2023] Open
Abstract
Synonymous genome recoding has been widely used to study different aspects of virus biology. Codon usage affects the temporal regulation of viral gene expression. In this study, we performed synonymous codon mutagenesis to investigate whether codon usage affected HIV-1 Env protein expression and virus viability. We replaced the codons AGG, GAG, CCU, ACU, CUC, and GGG of the HIV-1 env gene with the synonymous codons CGU, GAA, CCG, ACG, UUA, and GGA, respectively. We found that recoding the Env protein gp120 coding region (excluding the Rev response element [RRE]) did not significantly affect virus replication capacity, even though we introduced 15 new CpG dinucleotides. In contrast, changing a single codon (AGG to CGU) located in the gp41 coding region (HXB2 env position 2125 to 2127), which was included in the intronic splicing silencer (ISS), completely abolished virus replication and Env expression. Computational analyses of this mutant revealed a severe disruption in the ISS RNA secondary structure. A variant that restored ISS secondary RNA structure also reestablished Env production and virus viability. Interestingly, this codon variant prevented both virus replication and Env translation in a eukaryotic expression system. These findings suggested that disrupting mRNA splicing was not the only means of inhibiting translation. Our findings indicated that synonymous gp120 recoding was not always deleterious to HIV-1 replication. Importantly¸ we found that disrupting an external ISS loop strongly affected HIV-1 replication and Env translation.IMPORTANCE Synonymous substitutions can influence virus phenotype, replication capacity, and virulence. In this study, we explored how synonymous codon mutations impacted HIV-1 Env protein expression and virus replication capacity. We changed a single codon, AGG to CGU, which was located in the gp41 coding region (env nucleotide residues 2125 to 2127) and was included in the HIV-1 intronic splicing silencer. This change completely abolished virus replication and Env expression. We also found that changing codon usage in the gp120 region by including an increased number of CpG dinucleotides did not significantly affect Env expression or virus viability. Our findings showed that synonymous recoding was useful for altering viral phenotype and exploring virus biology.
Collapse
|
7
|
Boyd PS, Brown JB, Brown JD, Catazaro J, Chaudry I, Ding P, Dong X, Marchant J, O’Hern CT, Singh K, Swanson C, Summers MF, Yasin S. NMR Studies of Retroviral Genome Packaging. Viruses 2020; 12:v12101115. [PMID: 33008123 PMCID: PMC7599994 DOI: 10.3390/v12101115] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Revised: 09/18/2020] [Accepted: 09/26/2020] [Indexed: 12/03/2022] Open
Abstract
Nearly all retroviruses selectively package two copies of their unspliced RNA genomes from a cellular milieu that contains a substantial excess of non-viral and spliced viral RNAs. Over the past four decades, combinations of genetic experiments, phylogenetic analyses, nucleotide accessibility mapping, in silico RNA structure predictions, and biophysical experiments were employed to understand how retroviral genomes are selected for packaging. Genetic studies provided early clues regarding the protein and RNA elements required for packaging, and nucleotide accessibility mapping experiments provided insights into the secondary structures of functionally important elements in the genome. Three-dimensional structural determinants of packaging were primarily derived by nuclear magnetic resonance (NMR) spectroscopy. A key advantage of NMR, relative to other methods for determining biomolecular structure (such as X-ray crystallography), is that it is well suited for studies of conformationally dynamic and heterogeneous systems—a hallmark of the retrovirus packaging machinery. Here, we review advances in understanding of the structures, dynamics, and interactions of the proteins and RNA elements involved in retroviral genome selection and packaging that are facilitated by NMR.
Collapse
|
8
|
Chang AT, Chen L, Song L, Zhang S, Nikonowicz EP. 2-Amino-1,3-benzothiazole-6-carboxamide Preferentially Binds the Tandem Mismatch Motif r(UY:GA). Biochemistry 2020; 59:3225-3234. [PMID: 32786414 DOI: 10.1021/acs.biochem.0c00369] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
RNA helices are often punctuated with non-Watson-Crick features that may be targeted by chemical compounds, but progress toward identifying such compounds has been slow. We embedded a tandem UU:GA mismatch motif (5'-UG-3':5'-AU-3') within an RNA hairpin stem to identify compounds that bind the motif specifically. The three-dimensional structure of the RNA hairpin and its interaction with a small molecule identified through virtual screening are presented. The G-A mismatch forms a sheared pair upon which the U-U base pair stacks. The hydrogen bond configuration of the U-U pair involves O2 of the U adjacent to the G and O4 of the U adjacent to the A. The G-A and U-U pairs are flanked by A-U and G-C base pairs, respectively, and the stability of the mismatch is greater than when the motif is within the context of other flanking base pairs or when the 5'-3' orientation of the G-A and U-U pairs is swapped. Residual dipolar coupling constants were used to generate an ensemble of structures against which a virtual screen of 64480 small molecules was performed. The tandem mismatch was found to be specific for one compound, 2-amino-1,3-benzothiazole-6-carboxamide, which binds with moderate affinity but extends the motif to include the flanking A-U and G-C base pairs. The finding that the affinity for the UU:GA mismatch is dependent on flanking sequence emphasizes the importance of the motif context and potentially increases the number of small noncanonical features within RNA that can be specifically targeted by small molecules.
Collapse
Affiliation(s)
- Andrew T Chang
- Department of BioSciences, Rice University, 6100 Main Street, Houston, Texas 77251-1892, United States.,Department of Medicine, Division of Endocrinology, Gerontology, and Metabolism, Stanford Medicine, Stanford, California 94305-5103, United States
| | - Lu Chen
- Intelligent Molecular Discovery Laboratory, Department of Experimental Therapeutics, M. D. Anderson Cancer Center, 1901 East Road, Houston, Texas 77054, United States
| | - Luo Song
- Intelligent Molecular Discovery Laboratory, Department of Experimental Therapeutics, M. D. Anderson Cancer Center, 1901 East Road, Houston, Texas 77054, United States
| | - Shuxing Zhang
- Intelligent Molecular Discovery Laboratory, Department of Experimental Therapeutics, M. D. Anderson Cancer Center, 1901 East Road, Houston, Texas 77054, United States
| | - Edward P Nikonowicz
- Department of BioSciences, Rice University, 6100 Main Street, Houston, Texas 77251-1892, United States
| |
Collapse
|
9
|
Wan Q, Song D, Li H, He ML. Stress proteins: the biological functions in virus infection, present and challenges for target-based antiviral drug development. Signal Transduct Target Ther 2020; 5:125. [PMID: 32661235 PMCID: PMC7356129 DOI: 10.1038/s41392-020-00233-4] [Citation(s) in RCA: 68] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Revised: 05/26/2020] [Accepted: 06/13/2020] [Indexed: 02/06/2023] Open
Abstract
Stress proteins (SPs) including heat-shock proteins (HSPs), RNA chaperones, and ER associated stress proteins are molecular chaperones essential for cellular homeostasis. The major functions of HSPs include chaperoning misfolded or unfolded polypeptides, protecting cells from toxic stress, and presenting immune and inflammatory cytokines. Regarded as a double-edged sword, HSPs also cooperate with numerous viruses and cancer cells to promote their survival. RNA chaperones are a group of heterogeneous nuclear ribonucleoproteins (hnRNPs), which are essential factors for manipulating both the functions and metabolisms of pre-mRNAs/hnRNAs transcribed by RNA polymerase II. hnRNPs involve in a large number of cellular processes, including chromatin remodelling, transcription regulation, RNP assembly and stabilization, RNA export, virus replication, histone-like nucleoid structuring, and even intracellular immunity. Dysregulation of stress proteins is associated with many human diseases including human cancer, cardiovascular diseases, neurodegenerative diseases (e.g., Parkinson’s diseases, Alzheimer disease), stroke and infectious diseases. In this review, we summarized the biologic function of stress proteins, and current progress on their mechanisms related to virus reproduction and diseases caused by virus infections. As SPs also attract a great interest as potential antiviral targets (e.g., COVID-19), we also discuss the present progress and challenges in this area of HSP-based drug development, as well as with compounds already under clinical evaluation.
Collapse
Affiliation(s)
- Qianya Wan
- Department of Biomedical Sciences, City University of Hong Kong, Kowloon, Hong Kong, China
| | - Dan Song
- Department of Biomedical Sciences, City University of Hong Kong, Kowloon, Hong Kong, China
| | - Huangcan Li
- Department of Biomedical Sciences, City University of Hong Kong, Kowloon, Hong Kong, China
| | - Ming-Liang He
- Department of Biomedical Sciences, City University of Hong Kong, Kowloon, Hong Kong, China. .,CityU Shenzhen Research Institute, Shenzhen, China.
| |
Collapse
|
10
|
Wu J, Zhou C, Li J, Li C, Tao X, Leontis NB, Zirbel CL, Bisaro DM, Ding B. Functional analysis reveals G/U pairs critical for replication and trafficking of an infectious non-coding viroid RNA. Nucleic Acids Res 2020; 48:3134-3155. [PMID: 32083649 PMCID: PMC7102988 DOI: 10.1093/nar/gkaa100] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Revised: 02/03/2020] [Accepted: 02/18/2020] [Indexed: 01/19/2023] Open
Abstract
While G/U pairs are present in many RNAs, the lack of molecular studies to characterize the roles of multiple G/U pairs within a single RNA limits our understanding of their biological significance. From known RNA 3D structures, we observed that the probability a G/U will form a Watson-Crick (WC) base pair depends on sequence context. We analyzed 17 G/U pairs in the 359-nucleotide genome of Potato spindle tuber viroid (PSTVd), a circular non-coding RNA that replicates and spreads systemically in host plants. Most putative G/U base pairs were experimentally supported by selective 2'-hydroxyl acylation analyzed by primer extension (SHAPE). Deep sequencing PSTVd genomes from plants inoculated with a cloned master sequence revealed naturally occurring variants, and showed that G/U pairs are maintained to the same extent as canonical WC base pairs. Comprehensive mutational analysis demonstrated that nearly all G/U pairs are critical for replication and/or systemic spread. Two selected G/U pairs were found to be required for PSTVd entry into, but not for exit from, the host vascular system. This study identifies critical roles for G/U pairs in the survival of an infectious RNA, and increases understanding of structure-based regulation of replication and trafficking of pathogen and cellular RNAs.
Collapse
Affiliation(s)
- Jian Wu
- Department of Molecular Genetics, Center for Applied Plant Sciences, Center for RNA Biology, and Infectious Diseases Institute, The Ohio State University, Columbus, OH 43210, USA.,Graduate Program in Molecular, Cellular, and Developmental Biology, The Ohio State University, Columbus, OH 43210, USA
| | - Cuiji Zhou
- Department of Molecular Genetics, Center for Applied Plant Sciences, Center for RNA Biology, and Infectious Diseases Institute, The Ohio State University, Columbus, OH 43210, USA
| | - James Li
- Department of Molecular Genetics, Center for Applied Plant Sciences, Center for RNA Biology, and Infectious Diseases Institute, The Ohio State University, Columbus, OH 43210, USA
| | - Chun Li
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing 210095, China
| | - Xiaorong Tao
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing 210095, China
| | - Neocles B Leontis
- Department of Chemistry, Bowling Green State University, Bowling Green, OH 43403, USA
| | - Craig L Zirbel
- Department of Mathematics and Statistics, Bowling Green State University, Bowling Green, OH 43403, USA
| | - David M Bisaro
- Department of Molecular Genetics, Center for Applied Plant Sciences, Center for RNA Biology, and Infectious Diseases Institute, The Ohio State University, Columbus, OH 43210, USA.,Graduate Program in Molecular, Cellular, and Developmental Biology, The Ohio State University, Columbus, OH 43210, USA
| | - Biao Ding
- Department of Molecular Genetics, Center for Applied Plant Sciences, Center for RNA Biology, and Infectious Diseases Institute, The Ohio State University, Columbus, OH 43210, USA.,Graduate Program in Molecular, Cellular, and Developmental Biology, The Ohio State University, Columbus, OH 43210, USA
| |
Collapse
|
11
|
Rodríguez CF, Pal M, Muñoz-Hernandez H, Pearl LH, Llorca O. Modeling of a 14 kDa RUVBL2-Binding Domain with Medium Resolution Cryo-EM Density. J Chem Inf Model 2020; 60:2541-2551. [PMID: 32175735 DOI: 10.1021/acs.jcim.9b01095] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The number of high-resolution structures of protein complexes obtained using cryo-electron microscopy (cryo-EM) is increasing rapidly. Cryo-EM maps of large macromolecular complexes frequently contain regions resolved at different resolution levels, and modeling atomic structures de novo can be difficult for domains determined at worse than 5 Å in the absence of atomic information from other structures. Here we describe the details and step-by-step decisions in the strategy we followed to model the RUVBL2-binding domain (RBD), a 14 kDa domain at the C-terminus of RNA Polymerase II associated protein 3 (RPAP3) for which atomic information was not available. Modeling was performed on a cryo-EM map at 4.0-5.5 Å resolution, integrating information from secondary structure predictions, homology modeling, restraints from cross-linked mass spectrometry, and molecular dynamics (MD) in AMBER. Here, we compare our model with the structure of RBD determined by NMR to evaluate our strategy. We also perform new MD simulations to describe important residues mediating the interaction of RBD with RUVBL2 and analyze their conservation in RBD homologous domains. Our approach and its evaluation can serve as an example to address the analysis of medium resolution regions in cryo-EM maps.
Collapse
Affiliation(s)
- Carlos F Rodríguez
- Structural Biology Programme, Spanish National Cancer Research Centre (CNIO), Melchor Fernández Almagro 3, 28029 Madrid, Spain
| | - Mohinder Pal
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer, Brighton BN1 9RH, U.K
| | - Hugo Muñoz-Hernandez
- Structural Biology Programme, Spanish National Cancer Research Centre (CNIO), Melchor Fernández Almagro 3, 28029 Madrid, Spain
| | - Laurence H Pearl
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer, Brighton BN1 9RH, U.K
| | - Oscar Llorca
- Structural Biology Programme, Spanish National Cancer Research Centre (CNIO), Melchor Fernández Almagro 3, 28029 Madrid, Spain
| |
Collapse
|
12
|
Jin F, Xiao D, Zhao T, Yu M. Proteasome inhibitor MG132 suppresses pancreatic ductal adenocarcinoma-cell migration by increasing ESE3 expression. Oncol Lett 2019; 19:858-868. [PMID: 31897200 PMCID: PMC6924158 DOI: 10.3892/ol.2019.11157] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Accepted: 09/27/2019] [Indexed: 12/26/2022] Open
Abstract
The clinical significance of the proteasome inhibitor MG132 has been examined in numerous human cancer types; however, its influence on the metastasis and progression of pancreatic cancer is yet to be determined. In the present study, the effect of MG132 treatment on pancreatic ductal adenocarcinoma (PDAC) cell lines (SW1990 and PANC-1) was examined. Compared with the control groups, MG132 treatment resulted in higher expression levels of ETS homologous factor (ESE3), a crucial member of the E26 transformation-specific family that is central to various differentiation and development processes in epithelial tissues. MG132 treatment also increased the nuclear translocation of ESE3. Mechanistically, MG132 further inhibited the invasion and migration of PDAC cells by promoting E-cadherin expression, which not only plays an important role in cell-cell adhesion, but is also a direct target of ESE3. Furthermore, subsequent knockdown experiments, using short interfering RNAs, demonstrated that MG132 upregulated E-cadherin via an increase in ESE3 expression. The results of the present study support the hypothesis that MG132 treatment inhibits PDAC metastasis, highlighting the potential of MG132 as a therapeutic agent for the treatment of patients with PDAC.
Collapse
Affiliation(s)
- Fanjie Jin
- Department of Pancreatic Cancer, Tianjin Medical University Cancer Institute and Hospital, National Clinical Research Center for Cancer, Key Laboratory of Cancer Prevention and Therapy, Tianjin 300060, P.R. China
| | - Di Xiao
- Department of Nutrition and Food Science, School of Public Health, Tianjin Medical University, Tianjin 300070, P.R. China
| | - Tiansuo Zhao
- Department of Pancreatic Cancer, Tianjin Medical University Cancer Institute and Hospital, National Clinical Research Center for Cancer, Key Laboratory of Cancer Prevention and Therapy, Tianjin 300060, P.R. China
| | - Ming Yu
- Department of Nutrition and Food Science, School of Public Health, Tianjin Medical University, Tianjin 300070, P.R. China
| |
Collapse
|
13
|
Andrews RJ, Moss WN. Computational approaches for the discovery of splicing regulatory RNA structures. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2019; 1862:194380. [PMID: 31048028 DOI: 10.1016/j.bbagrm.2019.04.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Revised: 04/15/2019] [Accepted: 04/16/2019] [Indexed: 12/14/2022]
Abstract
Global RNA structure and local functional motifs mediate interactions important in determining the rates and patterns of mRNA splicing. In this review, we overview approaches for the computational prediction of RNA secondary structure with a special emphasis on the discovery of motifs important to RNA splicing. The process of identifying and modeling potential splicing regulatory structures is illustrated using a recently-developed approach for RNA structural motif discovery, the ScanFold pipeline, which is applied to the identification of a known splicing regulatory structure in influenza virus.
Collapse
Affiliation(s)
- Ryan J Andrews
- Roy J. Carver Department of Biochemistry, Biophysics, and Molecular Biology, Iowa State University, 2437 Pammel Drive, Ames, IA 50011, USA
| | - Walter N Moss
- Roy J. Carver Department of Biochemistry, Biophysics, and Molecular Biology, Iowa State University, 2437 Pammel Drive, Ames, IA 50011, USA.
| |
Collapse
|
14
|
Zhang H, Keane SC. Advances that facilitate the study of large RNA structure and dynamics by nuclear magnetic resonance spectroscopy. WILEY INTERDISCIPLINARY REVIEWS-RNA 2019; 10:e1541. [PMID: 31025514 PMCID: PMC7169810 DOI: 10.1002/wrna.1541] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Revised: 01/18/2019] [Accepted: 04/02/2019] [Indexed: 12/22/2022]
Abstract
The characterization of functional yet nonprotein coding (nc) RNAs has expanded the role of RNA in the cell from a passive player in the central dogma of molecular biology to an active regulator of gene expression. The misregulation of ncRNA function has been linked with a variety of diseases and disorders ranging from cancers to neurodegeneration. However, a detailed molecular understanding of how ncRNAs function has been limited; due, in part, to the difficulties associated with obtaining high-resolution structures of large RNAs. Tertiary structure determination of RNA as a whole is hampered by various technical challenges, all of which are exacerbated as the size of the RNA increases. Namely, RNAs tend to be highly flexible and dynamic molecules, which are difficult to crystallize. Biomolecular nuclear magnetic resonance (NMR) spectroscopy offers a viable alternative to determining the structure of large RNA molecules that do not readily crystallize, but is itself hindered by some technical limitations. Recently, a series of advancements have allowed the biomolecular NMR field to overcome, at least in part, some of these limitations. These advances include improvements in sample preparation strategies as well as methodological improvements. Together, these innovations pave the way for the study of ever larger RNA molecules that have important biological function. This article is categorized under: RNA Structure and Dynamics > RNA Structure, Dynamics, and Chemistry Regulatory RNAs/RNAi/Riboswitches > Regulatory RNAs RNA Structure and Dynamics > Influence of RNA Structure in Biological Systems.
Collapse
Affiliation(s)
- Huaqun Zhang
- Biophysics Program, University of Michigan, Ann Arbor, Michigan
| | - Sarah C Keane
- Biophysics Program, University of Michigan, Ann Arbor, Michigan.,Department of Chemistry, University of Michigan, Ann Arbor, Michigan
| |
Collapse
|
15
|
Kumarasinghe N, Moss WN. Analysis of a structured intronic region of the LMP2 pre-mRNA from EBV reveals associations with human regulatory proteins and nuclear actin. BMC Res Notes 2019; 12:33. [PMID: 30658689 PMCID: PMC6339298 DOI: 10.1186/s13104-019-4070-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Accepted: 01/11/2019] [Indexed: 01/07/2023] Open
Abstract
Objective The pre-mRNA of the Epstein–Barr virus LMP2 (latent membrane protein 2) has a region of unusual RNA structure that partially spans two consecutive exons and the entire intervening intron; suggesting RNA folding might affect splicing—particularly via interactions with human regulatory proteins. To better understand the roles of protein associations with this structured intronic region, we undertook a combined bioinformatics (motif searching) and experimental analysis (biotin pulldowns and RNA immunoprecipitations) of protein binding. Result Characterization of the ribonucleoprotein composition of this region revealed several human proteins as interactors: regulatory proteins hnRNP A1 (heterogeneous nuclear ribonucleoprotein A1), hnRNP U, HuR (human antigen R), and PSF (polypyrimidine tract-binding protein-associated splicing factor), as well as, unexpectedly, the cytoskeletal protein actin. Treatment of EBV-positive cells with drugs that alter actin polymerization specifically showed marked effects on splicing in this region. This suggests a potentially novel role for nuclear actin in regulation of viral RNA splicing. Electronic supplementary material The online version of this article (10.1186/s13104-019-4070-1) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- Nuwanthika Kumarasinghe
- Roy J. Carver Department of Biochemistry, Biophysics, and Molecular Biology, Iowa State University, 2437 Pammel Drive, Ames, IA, 50011, USA
| | - Walter N Moss
- Roy J. Carver Department of Biochemistry, Biophysics, and Molecular Biology, Iowa State University, 2437 Pammel Drive, Ames, IA, 50011, USA.
| |
Collapse
|
16
|
Sertznig H, Hillebrand F, Erkelenz S, Schaal H, Widera M. Behind the scenes of HIV-1 replication: Alternative splicing as the dependency factor on the quiet. Virology 2018; 516:176-188. [PMID: 29407375 DOI: 10.1016/j.virol.2018.01.011] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Revised: 01/10/2018] [Accepted: 01/11/2018] [Indexed: 01/31/2023]
Abstract
Alternative splicing plays a key role in the HIV-1 life cycle and is essential to maintain an equilibrium of mRNAs that encode viral proteins and polyprotein-isoforms. In particular, since all early HIV-1 proteins are expressed from spliced intronless and late enzymatic and structural proteins from intron containing, i.e. splicing repressed viral mRNAs, cellular splicing factors and splicing regulatory proteins are crucial for the replication capacity. In this review, we will describe the complex network of cis-acting splicing regulatory elements (SREs), which are mainly localized in the neighbourhoods of all HIV-1 splice sites and warrant the proper ratio of individual transcript isoforms. Since SREs represent binding sites for trans-acting cellular splicing factors interacting with the cellular spliceosomal apparatus we will review the current knowledge of interactions between viral RNA and cellular proteins as well as their impact on viral replication. Finally, we will discuss potential therapeutic approaches targeting HIV-1 alternative splicing.
Collapse
Affiliation(s)
- Helene Sertznig
- Institute for Virology, University Hospital Essen, University of Duisburg-Essen, Essen, Germany
| | - Frank Hillebrand
- Institute of Virology, Heinrich Heine University, University Hospital, Düsseldorf, Germany
| | - Steffen Erkelenz
- Institute for Genetics, Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Germany
| | - Heiner Schaal
- Institute of Virology, Heinrich Heine University, University Hospital, Düsseldorf, Germany
| | - Marek Widera
- Institute for Virology, University Hospital Essen, University of Duisburg-Essen, Essen, Germany.
| |
Collapse
|
17
|
Zhang K, Keane SC, Su Z, Irobalieva RN, Chen M, Van V, Sciandra CA, Marchant J, Heng X, Schmid MF, Case DA, Ludtke SJ, Summers MF, Chiu W. Structure of the 30 kDa HIV-1 RNA Dimerization Signal by a Hybrid Cryo-EM, NMR, and Molecular Dynamics Approach. Structure 2018; 26:490-498.e3. [PMID: 29398526 PMCID: PMC5842133 DOI: 10.1016/j.str.2018.01.001] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2017] [Revised: 11/12/2017] [Accepted: 01/03/2018] [Indexed: 02/01/2023]
Abstract
Cryoelectron microscopy (cryo-EM) and nuclear magnetic resonance (NMR) spectroscopy are routinely used to determine structures of macromolecules with molecular weights over 65 and under 25 kDa, respectively. We combined these techniques to study a 30 kDa HIV-1 dimer initiation site RNA ([DIS]2; 47 nt/strand). A 9 Å cryo-EM map clearly shows major groove features of the double helix and a right-handed superhelical twist. Simulated cryo-EM maps generated from time-averaged molecular dynamics trajectories (10 ns) exhibited levels of detail similar to those in the experimental maps, suggesting internal structural flexibility limits the cryo-EM resolution. Simultaneous inclusion of the cryo-EM map and 2H-edited NMR-derived distance restraints during structure refinement generates a structure consistent with both datasets and supporting a flipped-out base within a conserved purine-rich bulge. Our findings demonstrate the power of combining global and local structural information from these techniques for structure determination of modest-sized RNAs.
Collapse
Affiliation(s)
- Kaiming Zhang
- National Center for Macromolecular Imaging, Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Sarah C Keane
- Howard Hughes Medical Institute (HHMI) and Department of Chemistry and Biochemistry, University of Maryland Baltimore County (UMBC), Baltimore, MD 21250, USA
| | - Zhaoming Su
- National Center for Macromolecular Imaging, Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Rossitza N Irobalieva
- National Center for Macromolecular Imaging, Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Muyuan Chen
- National Center for Macromolecular Imaging, Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Verna Van
- Howard Hughes Medical Institute (HHMI) and Department of Chemistry and Biochemistry, University of Maryland Baltimore County (UMBC), Baltimore, MD 21250, USA
| | - Carly A Sciandra
- Howard Hughes Medical Institute (HHMI) and Department of Chemistry and Biochemistry, University of Maryland Baltimore County (UMBC), Baltimore, MD 21250, USA
| | - Jan Marchant
- Howard Hughes Medical Institute (HHMI) and Department of Chemistry and Biochemistry, University of Maryland Baltimore County (UMBC), Baltimore, MD 21250, USA
| | - Xiao Heng
- Department of Biochemistry, University of Missouri-Columbia, Columbia, MO 65211, USA
| | - Michael F Schmid
- National Center for Macromolecular Imaging, Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - David A Case
- Department of Chemistry & Chemical Biology, Rutgers University, Piscataway, NJ 08854, USA.
| | - Steven J Ludtke
- National Center for Macromolecular Imaging, Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA.
| | - Michael F Summers
- Howard Hughes Medical Institute (HHMI) and Department of Chemistry and Biochemistry, University of Maryland Baltimore County (UMBC), Baltimore, MD 21250, USA.
| | - Wah Chiu
- National Center for Macromolecular Imaging, Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA.
| |
Collapse
|
18
|
Tolbert M, Morgan CE, Pollum M, Crespo-Hernández CE, Li ML, Brewer G, Tolbert BS. HnRNP A1 Alters the Structure of a Conserved Enterovirus IRES Domain to Stimulate Viral Translation. J Mol Biol 2017; 429:2841-2858. [PMID: 28625847 PMCID: PMC5610934 DOI: 10.1016/j.jmb.2017.06.007] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2017] [Revised: 06/08/2017] [Accepted: 06/08/2017] [Indexed: 01/25/2023]
Abstract
Enteroviruses use a type I Internal Ribosome Entry Site (IRES) structure to facilitate protein synthesis and promote genome replication. Type I IRES elements require auxiliary host proteins to organize RNA structure for 40S ribosomal subunit assembly. Heterogeneous nuclear ribonucleoprotein A1 stimulates enterovirus 71 (EV71) translation in part through specific interactions with its stem loop II (SLII) IRES domain. Here, we determined a conjoined NMR-small angle x-ray scattering structure of the EV71 SLII domain and a mutant that significantly attenuates viral replication by abrogating hnRNP A1 interactions. Native SLII adopts a locally compact structure wherein stacking interactions in a conserved 5'-AUAGC-3' bulge preorganize the adjacent helices at nearly orthogonal orientations. Mutating the bulge sequence to 5'-ACCCC-3' ablates base stacking in the loop and globally reorients the SLII structure. Biophysical titrations reveal that the 5'-AUAGC-3' bulge undergoes a conformational change to assemble a functional hnRNP A1-RNA complex. Importantly, IRES mutations that delete the bulge impair viral translation and completely inhibit replication. Thus, this work provides key details into how an EV71 IRES structure adapts to hijack a cellular protein, and it suggests that the SLII domain is a potential target for antiviral therapy.
Collapse
Affiliation(s)
- Michele Tolbert
- Department of Chemistry, Case Western Reserve University, Cleveland, OH, 44106-7078 USA
| | - Christopher E Morgan
- Department of Chemistry, Case Western Reserve University, Cleveland, OH, 44106-7078 USA
| | - Marvin Pollum
- Department of Chemistry, Case Western Reserve University, Cleveland, OH, 44106-7078 USA
| | | | - Mei-Ling Li
- Department of Biochemistry and Molecular Biology, Rutgers Robert Wood Johnson Medical School, Piscataway, NJ, 08854 USA
| | - Gary Brewer
- Department of Biochemistry and Molecular Biology, Rutgers Robert Wood Johnson Medical School, Piscataway, NJ, 08854 USA
| | - Blanton S Tolbert
- Department of Chemistry, Case Western Reserve University, Cleveland, OH, 44106-7078 USA.
| |
Collapse
|
19
|
Soemedi R, Cygan KJ, Rhine CL, Glidden DT, Taggart AJ, Lin CL, Fredericks AM, Fairbrother WG. The effects of structure on pre-mRNA processing and stability. Methods 2017; 125:36-44. [PMID: 28595983 DOI: 10.1016/j.ymeth.2017.06.001] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2017] [Revised: 05/31/2017] [Accepted: 06/01/2017] [Indexed: 12/16/2022] Open
Abstract
Pre-mRNA molecules can form a variety of structures, and both secondary and tertiary structures have important effects on processing, function and stability of these molecules. The prediction of RNA secondary structure is a challenging problem and various algorithms that use minimum free energy, maximum expected accuracy and comparative evolutionary based methods have been developed to predict secondary structures. However, these tools are not perfect, and this remains an active area of research. The secondary structure of pre-mRNA molecules can have an enhancing or inhibitory effect on pre-mRNA splicing. An example of enhancing structure can be found in a novel class of introns in zebrafish. About 10% of zebrafish genes contain a structured intron that forms a bridging hairpin that enforces correct splice site pairing. Negative examples of splicing include local structures around splice sites that decrease splicing efficiency and potentially cause mis-splicing leading to disease. Splicing mutations are a frequent cause of hereditary disease. The transcripts of disease genes are significantly more structured around the splice sites, and point mutations that increase the local structure often cause splicing disruptions. Post-splicing, RNA secondary structure can also affect the stability of the spliced intron and regulatory RNA interference pathway intermediates, such as pre-microRNAs. Additionally, RNA secondary structure has important roles in the innate immune defense against viruses. Finally, tertiary structure can also play a large role in pre-mRNA splicing. One example is the G-quadruplex structure, which, similar to secondary structure, can either enhance or inhibit splicing through mechanisms such as creating or obscuring RNA binding protein sites.
Collapse
Affiliation(s)
- Rachel Soemedi
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, 70 Ship Street, Providence, RI 02903, USA; Center for Computational Molecular Biology, Brown University, 115 Waterman Street, Providence, RI 02912, USA.
| | - Kamil J Cygan
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, 70 Ship Street, Providence, RI 02903, USA; Center for Computational Molecular Biology, Brown University, 115 Waterman Street, Providence, RI 02912, USA.
| | - Christy L Rhine
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, 70 Ship Street, Providence, RI 02903, USA.
| | - David T Glidden
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, 70 Ship Street, Providence, RI 02903, USA; Center for Computational Molecular Biology, Brown University, 115 Waterman Street, Providence, RI 02912, USA.
| | - Allison J Taggart
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, 70 Ship Street, Providence, RI 02903, USA.
| | - Chien-Ling Lin
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, 70 Ship Street, Providence, RI 02903, USA.
| | - Alger M Fredericks
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, 70 Ship Street, Providence, RI 02903, USA.
| | - William G Fairbrother
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, 70 Ship Street, Providence, RI 02903, USA; Center for Computational Molecular Biology, Brown University, 115 Waterman Street, Providence, RI 02912, USA.
| |
Collapse
|
20
|
Characterizing HIV-1 Splicing by Using Next-Generation Sequencing. J Virol 2017; 91:JVI.02515-16. [PMID: 28077653 DOI: 10.1128/jvi.02515-16] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2017] [Accepted: 01/04/2017] [Indexed: 02/07/2023] Open
Abstract
Full-length human immunodeficiency virus type 1 (HIV-1) RNA serves as the genome or as an mRNA, or this RNA undergoes splicing using four donors and 10 acceptors to create over 50 physiologically relevant transcripts in two size classes (1.8 kb and 4 kb). We developed an assay using Primer ID-tagged deep sequencing to quantify HIV-1 splicing. Using the lab strain NL4-3, we found that A5 (env/nef) is the most commonly used acceptor (about 50%) and A3 (tat) the least used (about 3%). Two small exons are made when a splice to acceptor A1 or A2 is followed by activation of donor D2 or D3, and the high-level use of D2 and D3 dramatically reduces the amount of vif and vpr transcripts. We observed distinct patterns of temperature sensitivity of splicing to acceptors A1 and A2. In addition, disruption of a conserved structure proximal to A1 caused a 10-fold reduction in all transcripts that utilized A1. Analysis of a panel of subtype B transmitted/founder viruses showed that splicing patterns are conserved, but with surprising variability of usage. A subtype C isolate was similar, while a simian immunodeficiency virus (SIV) isolate showed significant differences. We also observed transsplicing from a downstream donor on one transcript to an upstream acceptor on a different transcript, which we detected in 0.3% of 1.8-kb RNA reads. There were several examples of splicing suppression when the env intron was retained in the 4-kb size class. These results demonstrate the utility of this assay and identify new examples of HIV-1 splicing regulation. IMPORTANCE During HIV-1 replication, over 50 conserved spliced RNA variants are generated. The splicing assay described here uses new developments in deep-sequencing technology combined with Primer ID-tagged cDNA primers to efficiently quantify HIV-1 splicing at a depth that allows even low-frequency splice variants to be monitored. We have used this assay to examine several features of HIV-1 splicing and to identify new examples of different mechanisms of regulation of these splicing patterns. This splicing assay can be used to explore in detail how HIV-1 splicing is regulated and, with moderate throughput, could be used to screen for structural elements, small molecules, and host factors that alter these relatively conserved splicing patterns.
Collapse
|
21
|
Rules of RNA specificity of hnRNP A1 revealed by global and quantitative analysis of its affinity distribution. Proc Natl Acad Sci U S A 2017; 114:2206-2211. [PMID: 28193894 DOI: 10.1073/pnas.1616371114] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Heterogeneous nuclear ribonucleoprotein A1 (hnRNP A1) is a multipurpose RNA-binding protein (RBP) involved in normal and pathological RNA metabolism. Transcriptome-wide mapping and in vitro evolution identify consensus hnRNP A1 binding motifs; however, such data do not reveal how surrounding RNA sequence and structural context modulate affinity. We determined the affinity of hnRNP A1 for all possible sequence variants (n = 16,384) of the HIV exon splicing silencer 3 (ESS3) 7-nt apical loop. Analysis of the affinity distribution identifies the optimal motif 5'-YAG-3' and shows how its copy number, position in the loop, and loop structure modulate affinity. For a subset of ESS3 variants, we show that specificity is determined by association rate constants and that variants lacking the minimal sequence motif bind competitively with consensus RNA. Thus, the results reveal general rules of specificity of hnRNP A1 and provide a quantitative framework for understanding how it discriminates between alternative competing RNA ligands in vivo.
Collapse
|
22
|
Keane SC, Summers MF. NMR Studies of the Structure and Function of the HIV-1 5'-Leader. Viruses 2016; 8:v8120338. [PMID: 28009832 PMCID: PMC5192399 DOI: 10.3390/v8120338] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2016] [Revised: 12/15/2016] [Accepted: 12/16/2016] [Indexed: 12/25/2022] Open
Abstract
The 5′-leader of the human immunodeficiency virus type 1 (HIV-1) genome plays several critical roles during viral replication, including differentially establishing mRNA versus genomic RNA (gRNA) fates. As observed for proteins, the function of the RNA is tightly regulated by its structure, and a common paradigm has been that genome function is temporally modulated by structural changes in the 5′-leader. Over the past 30 years, combinations of nucleotide reactivity mapping experiments with biochemistry, mutagenesis, and phylogenetic studies have provided clues regarding the secondary structures of stretches of residues within the leader that adopt functionally discrete domains. More recently, nuclear magnetic resonance (NMR) spectroscopy approaches have been developed that enable direct detection of intra- and inter-molecular interactions within the intact leader, providing detailed insights into the structural determinants and mechanisms that regulate HIV-1 genome packaging and function.
Collapse
Affiliation(s)
- Sarah C Keane
- Howard Hughes Medical Institute, Department of Chemistry and Biochemistry, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250, USA.
| | - Michael F Summers
- Howard Hughes Medical Institute, Department of Chemistry and Biochemistry, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250, USA.
| |
Collapse
|