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Firdous Z, Kalra S, Chattopadhyay R, Bari VK. Current insight into the role of mRNA decay pathways in fungal pathogenesis. Microbiol Res 2024; 283:127671. [PMID: 38479232 DOI: 10.1016/j.micres.2024.127671] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2023] [Revised: 02/19/2024] [Accepted: 02/29/2024] [Indexed: 04/17/2024]
Abstract
Pathogenic fungal species can cause superficial and mucosal infections, to potentially fatal systemic or invasive infections in humans. These infections are more common in immunocompromised or critically ill patients and have a significant morbidity and fatality rate. Fungal pathogens utilize several strategies to adapt the host environment resulting in efficient and comprehensive alterations in their cellular metabolism. Fungal virulence is regulated by several factors and post-transcriptional regulation mechanisms involving mRNA molecules are one of them. Post-transcriptional controls have emerged as critical regulatory mechanisms involved in the pathogenesis of fungal species. The untranslated upstream and downstream regions of the mRNA, as well as RNA-binding proteins, regulate morphogenesis and virulence by controlling mRNA degradation and stability. The limited number of available therapeutic drugs, the emergence of multidrug resistance, and high death rates associated with systemic fungal illnesses pose a serious risk to human health. Therefore, new antifungal treatments that specifically target mRNA pathway components can decrease fungal pathogenicity and when combined increase the effectiveness of currently available antifungal drugs. This review summarizes the mRNA degradation pathways and their role in fungal pathogenesis.
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Affiliation(s)
- Zulikha Firdous
- Department of Biochemistry, School of Basic Sciences, Central University of Punjab, VPO-Ghudda, Bathinda 151401, India
| | - Sapna Kalra
- Department of Biochemistry, School of Basic Sciences, Central University of Punjab, VPO-Ghudda, Bathinda 151401, India
| | - Rituja Chattopadhyay
- Department of Biochemistry, School of Basic Sciences, Central University of Punjab, VPO-Ghudda, Bathinda 151401, India
| | - Vinay Kumar Bari
- Department of Biochemistry, School of Basic Sciences, Central University of Punjab, VPO-Ghudda, Bathinda 151401, India.
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2
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He F, Jacobson A. Eukaryotic mRNA decapping factors: molecular mechanisms and activity. FEBS J 2023; 290:5057-5085. [PMID: 36098474 PMCID: PMC10008757 DOI: 10.1111/febs.16626] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 08/11/2022] [Accepted: 09/12/2022] [Indexed: 11/30/2022]
Abstract
Decapping is the enzymatic removal of 5' cap structures from mRNAs in eukaryotic cells. Cap structures normally enhance mRNA translation and stability, and their excision commits an mRNA to complete 5'-3' exoribonucleolytic digestion and generally ends the physical and functional cellular presence of the mRNA. Decapping plays a pivotal role in eukaryotic cytoplasmic mRNA turnover and is a critical and highly regulated event in multiple 5'-3' mRNA decay pathways, including general 5'-3' decay, nonsense-mediated mRNA decay (NMD), AU-rich element-mediated mRNA decay, microRNA-mediated gene silencing, and targeted transcript-specific mRNA decay. In the yeast Saccharomyces cerevisiae, mRNA decapping is carried out by a single Dcp1-Dcp2 decapping enzyme in concert with the accessory activities of specific regulators commonly known as decapping activators or enhancers. These regulatory proteins include the general decapping activators Edc1, 2, and 3, Dhh1, Scd6, Pat1, and the Lsm1-7 complex, as well as the NMD-specific factors, Upf1, 2, and 3. Here, we focus on in vivo mRNA decapping regulation in yeast. We summarize recently uncovered molecular mechanisms that control selective targeting of the yeast decapping enzyme and discuss new roles for specific decapping activators in controlling decapping enzyme targeting, assembly of target-specific decapping complexes, and the monitoring of mRNA translation. Further, we discuss the kinetic contribution of mRNA decapping for overall decay of different substrate mRNAs and highlight experimental evidence pointing to the functional coordination and physical coupling between events in mRNA deadenylation, decapping, and 5'-3' exoribonucleolytic decay.
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Affiliation(s)
- Feng He
- Department of Microbiology and Physiological Systems, UMass Chan Medical School, 368 Plantation Street, Worcester, MA 01655
| | - Allan Jacobson
- Department of Microbiology and Physiological Systems, UMass Chan Medical School, 368 Plantation Street, Worcester, MA 01655
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3
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Krempl C, Lazzaretti D, Sprangers R. A structural biology view on the enzymes involved in eukaryotic mRNA turnover. Biol Chem 2023; 404:1101-1121. [PMID: 37709756 DOI: 10.1515/hsz-2023-0182] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Accepted: 08/24/2023] [Indexed: 09/16/2023]
Abstract
The cellular environment contains numerous ribonucleases that are dedicated to process mRNA transcripts that have been targeted for degradation. Here, we review the three dimensional structures of the ribonuclease complexes (Pan2-Pan3, Ccr4-Not, Xrn1, exosome) and the mRNA decapping enzymes (Dcp2, DcpS) that are involved in mRNA turnover. Structures of major parts of these proteins have been experimentally determined. These enzymes and factors do not act in isolation, but are embedded in interaction networks which regulate enzyme activity and ensure that the appropriate substrates are recruited. The structural details of the higher order complexes that form can, in part, be accurately deduced from known structural data of sub-complexes. Interestingly, many of the ribonuclease and decapping enzymes have been observed in structurally different conformations. Together with experimental data, this highlights that structural changes are often important for enzyme function. We conclude that the known structural data of mRNA decay factors provide important functional insights, but that static structural data needs to be complemented with information regarding protein motions to complete the picture of how transcripts are turned over. In addition, we highlight multiple aspects that influence mRNA turnover rates, but that have not been structurally characterized so far.
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Affiliation(s)
- Christina Krempl
- Institute of Biophysics and Physical Biochemistry, Regensburg Center for Biochemistry, University of Regensburg, D-93053 Regensburg, Germany
| | - Daniela Lazzaretti
- Institute of Biophysics and Physical Biochemistry, Regensburg Center for Biochemistry, University of Regensburg, D-93053 Regensburg, Germany
| | - Remco Sprangers
- Institute of Biophysics and Physical Biochemistry, Regensburg Center for Biochemistry, University of Regensburg, D-93053 Regensburg, Germany
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4
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Photocaged 5' cap analogues for optical control of mRNA translation in cells. Nat Chem 2022; 14:905-913. [PMID: 35725774 PMCID: PMC7613264 DOI: 10.1038/s41557-022-00972-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Accepted: 05/11/2022] [Indexed: 11/08/2022]
Abstract
The translation of messenger RNA (mRNA) is a fundamental process in gene expression, and control of translation is important to regulate protein synthesis in cells. The primary hallmark of eukaryotic mRNAs is their 5′ cap, whose molecular contacts to the eukaryotic translation initiation factor eIF4E govern the initiation of translation. Here we report 5′ cap analogues with photo-cleavable groups (FlashCaps) that prohibit binding to eIF4E and resist cleavage by decapping enzymes. These compounds are compatible with the general and efficient production of mRNAs by in vitro transcription. In FlashCap-mRNAs, the single photocaging group abrogates translation in vitro and in mammalian cells without increasing immunogenicity. Irradiation restores the native cap, triggering efficient translation. FlashCaps overcome the problem of remaining sequence or structure changes in mRNA after irradiation that limited previous designs. Together, these results demonstrate that FlashCaps offer a route to regulate the expression of any given mRNA and to dose mRNA therapeutics with spatio-temporal control. ![]()
Analogues of mRNA 5′ caps containing a photo-cleavable group have now been developed. These so-called FlashCaps can be used for routine in vitro transcription to make long mRNAs containing a cap. In cells, the capped mRNAs are translationally muted; however, upon irradiation by light, the photo-cleavable group is removed without leaving any remaining modification and mRNA is then translated into the corresponding protein.
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5
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He F, Wu C, Jacobson A. Dcp2 C-terminal cis-binding elements control selective targeting of the decapping enzyme by forming distinct decapping complexes. eLife 2022; 11:74410. [PMID: 35604319 PMCID: PMC9170289 DOI: 10.7554/elife.74410] [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: 10/04/2021] [Accepted: 05/22/2022] [Indexed: 11/13/2022] Open
Abstract
A single Dcp1-Dcp2 decapping enzyme targets diverse classes of yeast mRNAs for decapping-dependent 5' to 3' decay, but the molecular mechanisms controlling mRNA selectivity by the enzyme remain elusive. Through extensive genetic analyses we reveal that Dcp2 C-terminal domain cis-regulatory elements control decapping enzyme target specificity by orchestrating formation of distinct decapping complexes. Two Upf1-binding motifs direct the decapping enzyme to NMD substrates, a single Edc3-binding motif targets both Edc3 and Dhh1 substrates, and Pat1-binding leucine-rich motifs target Edc3 and Dhh1 substrates under selective conditions. Although it functions as a unique targeting component of specific complexes, Edc3 is a common component of multiple complexes. Scd6 and Xrn1 also have specific binding sites on Dcp2, allowing them to be directly recruited to decapping complexes. Collectively, our results demonstrate that Upf1, Edc3, Scd6, and Pat1 function as regulatory subunits of the holo-decapping enzyme, controlling both its substrate specificity and enzymatic activation.
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Affiliation(s)
- Feng He
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, United States
| | - Chan Wu
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, United States
| | - Allan Jacobson
- Department of Microbiology and Physiological Systems, University of Massachusetts Chan Medical School, Worcester, United States
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6
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Abstract
The 5'-terminal cap is a fundamental determinant of eukaryotic gene expression which facilitates cap-dependent translation and protects mRNAs from exonucleolytic degradation. Enzyme-directed hydrolysis of the cap (decapping) decisively affects mRNA expression and turnover, and is a heavily regulated event. Following the identification of the decapping holoenzyme (Dcp1/2) over two decades ago, numerous studies revealed the complexity of decapping regulation across species and cell types. A conserved set of Dcp1/2-associated proteins, implicated in decapping activation and molecular scaffolding, were identified through genetic and molecular interaction studies, and yet their exact mechanisms of action are only emerging. In this review, we discuss the prevailing models on the roles and assembly of decapping co-factors, with considerations of conservation across species and comparison across physiological contexts. We next discuss the functional convergences of decapping machineries with other RNA-protein complexes in cytoplasmic P bodies and compare current views on their impact on mRNA stability and translation. Lastly, we review the current models of decapping activation and highlight important gaps in our current understanding.
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Affiliation(s)
- Elva Vidya
- Goodman Cancer Institute, McGill University, Montréal, QC, Canada
- Department of Biochemistry, McGill University, Montréal, QC, Canada
| | - Thomas F. Duchaine
- Goodman Cancer Institute, McGill University, Montréal, QC, Canada
- Department of Biochemistry, McGill University, Montréal, QC, Canada
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7
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Peters JK, Tibble RW, Warminski M, Jemielity J, Gross JD. Structure of the poxvirus decapping enzyme D9 reveals its mechanism of cap recognition and catalysis. Structure 2022; 30:721-732.e4. [PMID: 35290794 PMCID: PMC9081138 DOI: 10.1016/j.str.2022.02.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2021] [Revised: 12/30/2021] [Accepted: 02/16/2022] [Indexed: 01/06/2023]
Abstract
Poxviruses encode decapping enzymes that remove the protective 5' cap from both host and viral mRNAs to commit transcripts for decay by the cellular exonuclease Xrn1. Decapping by these enzymes is critical for poxvirus pathogenicity by means of simultaneously suppressing host protein synthesis and limiting the accumulation of viral double-stranded RNA (dsRNA), a trigger for antiviral responses. Here we present a high-resolution structural view of the vaccinia virus decapping enzyme D9. This Nudix enzyme contains a domain organization different from other decapping enzymes in which a three-helix bundle is inserted into the catalytic Nudix domain. The 5' mRNA cap is positioned in a bipartite active site at the interface of the two domains. Specificity for the methylated guanosine cap is achieved by stacking between conserved aromatic residues in a manner similar to that observed in canonical cap-binding proteins VP39, eIF4E, and CBP20, and distinct from eukaryotic decapping enzyme Dcp2.
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8
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Guillemin A, Kumar A, Wencker M, Ricci EP. Shaping the Innate Immune Response Through Post-Transcriptional Regulation of Gene Expression Mediated by RNA-Binding Proteins. Front Immunol 2022; 12:796012. [PMID: 35087521 PMCID: PMC8787094 DOI: 10.3389/fimmu.2021.796012] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Accepted: 12/13/2021] [Indexed: 12/20/2022] Open
Abstract
Innate immunity is the frontline of defense against infections and tissue damage. It is a fast and semi-specific response involving a myriad of processes essential for protecting the organism. These reactions promote the clearance of danger by activating, among others, an inflammatory response, the complement cascade and by recruiting the adaptive immunity. Any disequilibrium in this functional balance can lead to either inflammation-mediated tissue damage or defense inefficiency. A dynamic and coordinated gene expression program lies at the heart of the innate immune response. This expression program varies depending on the cell-type and the specific danger signal encountered by the cell and involves multiple layers of regulation. While these are achieved mainly via transcriptional control of gene expression, numerous post-transcriptional regulatory pathways involving RNA-binding proteins (RBPs) and other effectors play a critical role in its fine-tuning. Alternative splicing, translational control and mRNA stability have been shown to be tightly regulated during the innate immune response and participate in modulating gene expression in a global or gene specific manner. More recently, microRNAs assisting RBPs and post-transcriptional modification of RNA bases are also emerging as essential players of the innate immune process. In this review, we highlight the numerous roles played by specific RNA-binding effectors in mediating post-transcriptional control of gene expression to shape innate immunity.
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Affiliation(s)
- Anissa Guillemin
- LBMC, Laboratoire de Biologie et Modelisation de la Cellule, Université de Lyon, ENS de Lyon, Universite Claude Bernard Lyon 1, CNRS, UMR 5239, INSERM, U1293, Lyon, France
| | - Anuj Kumar
- CRCL, Centre de Recherche en Cancérologie de Lyon, INSERM U1052, CNRS UMR 5286, Lyon, France
| | - Mélanie Wencker
- LBMC, Laboratoire de Biologie et Modelisation de la Cellule, Université de Lyon, ENS de Lyon, Universite Claude Bernard Lyon 1, CNRS, UMR 5239, INSERM, U1293, Lyon, France
- CIRI, Centre International de Recherche en Infectiologie, Université de Lyon, ENS de Lyon, CNRS, UMR 5308, INSERM, Lyon, France
| | - Emiliano P. Ricci
- LBMC, Laboratoire de Biologie et Modelisation de la Cellule, Université de Lyon, ENS de Lyon, Universite Claude Bernard Lyon 1, CNRS, UMR 5239, INSERM, U1293, Lyon, France
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9
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Depaix A, Mlynarska-Cieslak A, Warminski M, Sikorski PJ, Jemielity J, Kowalska J. RNA Ligation for Mono and Dually Labeled RNAs. Chemistry 2021; 27:12190-12197. [PMID: 34114681 DOI: 10.1002/chem.202101909] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Indexed: 12/27/2022]
Abstract
Labeled RNAs are invaluable probes for investigation of RNA function and localization. However, mRNA labeling remains challenging. Here, we developed an improved method for 3'-end labeling of in vitro transcribed RNAs. We synthesized novel adenosine 3',5'-bisphosphate analogues modified at the N6 or C2 position of adenosine with an azide-containing linker, fluorescent label, or biotin and assessed these constructs as substrates for RNA labeling directly by T4 ligase or via postenzymatic strain-promoted alkyne-azide cycloaddition (SPAAC). All analogues were substrates for T4 RNA ligase. Analogues containing bulky fluorescent labels or biotin showed better overall labeling yields than postenzymatic SPAAC. We successfully labeled uncapped RNAs, NAD-capped RNAs, and 5'-fluorescently labeled m7 Gp3 Am -capped mRNAs. The obtained highly homogenous dually labeled mRNA was translationally active and enabled fluorescence-based monitoring of decapping. This method will facilitate the use of various functionalized mRNA-based probes.
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Affiliation(s)
- Anaïs Depaix
- Division of Biophysics, Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Pasteura 5, 02-093, Warsaw, Poland
| | - Agnieszka Mlynarska-Cieslak
- Division of Biophysics, Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Pasteura 5, 02-093, Warsaw, Poland
| | - Marcin Warminski
- Division of Biophysics, Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Pasteura 5, 02-093, Warsaw, Poland
| | - Pawel J Sikorski
- Centre of New Technologies, University of Warsaw, Banacha 2c, 02-097, Warsaw, Poland
| | - Jacek Jemielity
- Centre of New Technologies, University of Warsaw, Banacha 2c, 02-097, Warsaw, Poland
| | - Joanna Kowalska
- Division of Biophysics, Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Pasteura 5, 02-093, Warsaw, Poland
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10
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Biomolecular condensates amplify mRNA decapping by biasing enzyme conformation. Nat Chem Biol 2021; 17:615-623. [PMID: 33767388 PMCID: PMC8476181 DOI: 10.1038/s41589-021-00774-x] [Citation(s) in RCA: 41] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Accepted: 02/16/2021] [Indexed: 02/07/2023]
Abstract
Cells organize biochemical processes into biological condensates. P-bodies are cytoplasmic condensates that are enriched in enzymes important for mRNA degradation and have been identified as sites of both storage and decay. How these opposing outcomes can be achieved in condensates remains unresolved. mRNA decapping immediately precedes degradation, and the Dcp1/Dcp2 decapping complex is enriched in P-bodies. Here, we show that Dcp1/Dcp2 activity is modulated in condensates and depends on the interactions promoting phase separation. We find that Dcp1/Dcp2 phase separation stabilizes an inactive conformation in Dcp2 to inhibit decapping. The activator Edc3 causes a conformational change in Dcp2 and rewires the protein-protein interactions to stimulate decapping in condensates. Disruption of the inactive conformation dysregulates decapping in condensates. Our results indicate that the regulation of enzymatic activity in condensates relies on a coupling across length scales ranging from microns to ångstroms. We propose that this regulatory mechanism may control the functional state of P-bodies and related phase-separated compartments.
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11
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Xing W, Muhlrad D, Parker R, Rosen MK. A quantitative inventory of yeast P body proteins reveals principles of composition and specificity. eLife 2020; 9:56525. [PMID: 32553117 PMCID: PMC7373430 DOI: 10.7554/elife.56525] [Citation(s) in RCA: 72] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Accepted: 06/18/2020] [Indexed: 01/01/2023] Open
Abstract
P bodies are archetypal biomolecular condensates that concentrate proteins and RNA without a surrounding membrane. While dozens of P body proteins are known, the concentrations of components in the compartment have not been measured. We used live cell imaging to generate a quantitative inventory of the major proteins in yeast P bodies. Only seven proteins are highly concentrated in P bodies (5.1–15µM); the 24 others examined are appreciably lower (most ≤ 2.6µM). P body concentration correlates inversely with cytoplasmic exchange rate. Sequence elements driving Dcp2 concentration into P bodies are distributed across the protein and act synergistically. Our data indicate that P bodies, and probably other condensates, are compositionally simpler than suggested by proteomic analyses, with implications for specificity, reconstitution and evolution.
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Affiliation(s)
- Wenmin Xing
- Department of Biophysics, Howard Hughes Medical Institute, UT Southwestern Medical Center, Dallas, United States
| | - Denise Muhlrad
- Department of Biochemistry, Howard Hughes Medical Institute, University of Colorado, Boulder, United States
| | - Roy Parker
- Department of Biochemistry, Howard Hughes Medical Institute, University of Colorado, Boulder, United States
| | - Michael K Rosen
- Department of Biophysics, Howard Hughes Medical Institute, UT Southwestern Medical Center, Dallas, United States
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12
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Ray A, Frick DN. Fluorescent probe displacement assays reveal unique nucleic acid binding properties of human nudix enzymes. Anal Biochem 2020; 595:113622. [PMID: 32059949 PMCID: PMC7087442 DOI: 10.1016/j.ab.2020.113622] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2020] [Accepted: 02/10/2020] [Indexed: 12/21/2022]
Abstract
Nudix proteins are members of a large family of homologous enzymes that hydrolyze nucleoside diphosphates linked to other compounds. The substrates for a subset of Nudix enzymes are all nucleotides linked to RNA, like the m7G mRNA caps and the more recently discovered NAD(H) RNA caps. However, the RNA affinity and nucleic acid specificity of Nudix proteins has not yet been explored in depth. In this study we designed new fluorescence-based assays to examine the interaction of purified recombinant E. coli NudC and human Nudt1 (aka MTH1) Nudt3, Nudt12, Nudt16, and Nudt20 (aka Dcp2). All Nudix proteins except Nudt1 and Nudt12 bound both RNA and DNA stoichiometrically with high affinity (dissociation constants in the nanomolar range) and no clear sequence specificity. In stark contrast, Nudt12 binds RNA but not similar DNA oligonucleotides. Nudt12 also bound RNAs with 5' NAD+ caps more tightly than those with NADH or m7G cap. NudC was similarly selective against m7G caps but did not differentiate between NAD+ and NADH capped RNA. Nudt3, Nudt16, and Nudt20 bound m7G capped RNA more tightly than RNA with NADH caps.
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Affiliation(s)
- Atreyei Ray
- Department of Chemistry & Biochemistry, The University of Wisconsin- Milwaukee, Milwaukee, WI, 53217, USA
| | - David N Frick
- Department of Chemistry & Biochemistry, The University of Wisconsin- Milwaukee, Milwaukee, WI, 53217, USA.
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13
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Wurm JP, Sprangers R. Dcp2: an mRNA decapping enzyme that adopts many different shapes and forms. Curr Opin Struct Biol 2019; 59:115-123. [PMID: 31473440 PMCID: PMC6900585 DOI: 10.1016/j.sbi.2019.07.009] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2019] [Revised: 07/22/2019] [Accepted: 07/30/2019] [Indexed: 02/01/2023]
Abstract
Structure of the active state of the Dcp2 decapping enzyme. Insights into the structural states that are sampled in solution. Details regarding the intermolecular network that Dcp2 is embedded in.
Eukaryotic mRNAs contain a 5’ cap structure that protects the transcript against rapid exonucleolytic degradation. The regulation of cellular mRNA levels therefore depends on a precise control of the mRNA decapping pathways. The major mRNA decapping enzyme in eukaryotic cells is Dcp2. It is regulated by interactions with several activators, including Dcp1, Edc1, and Edc3, as well as by an autoinhibition mechanism. The structural and mechanistical characterization of Dcp2 complexes has long been impeded by the high flexibility and dynamic nature of the enzyme. Here we review recent insights into the catalytically active conformation of the mRNA decapping complex, the mode of action of decapping activators and the large interactions network that Dcp2 is embedded in.
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Affiliation(s)
- Jan Philip Wurm
- Department of Biophysics I, University of Regensburg, 93053, Regensburg, Germany.
| | - Remco Sprangers
- Department of Biophysics I, University of Regensburg, 93053, Regensburg, Germany.
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14
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Paquette DR, Tibble RW, Daifuku TS, Gross JD. Control of mRNA decapping by autoinhibition. Nucleic Acids Res 2019; 46:6318-6329. [PMID: 29618050 PMCID: PMC6158755 DOI: 10.1093/nar/gky233] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2017] [Accepted: 03/19/2018] [Indexed: 12/11/2022] Open
Abstract
5′ mediated cytoplasmic RNA decay is a conserved cellular process in eukaryotes. While the functions of the structured core domains in this pathway are well-studied, the role of abundant intrinsically disordered regions (IDRs) is lacking. Here we reconstitute the Dcp1:Dcp2 complex containing a portion of the disordered C-terminus and show its activity is autoinhibited by linear interaction motifs. Enhancers of decapping (Edc) 1 and 3 cooperate to activate decapping by different mechanisms: Edc3 alleviates autoinhibition by binding IDRs and destabilizing an inactive form of the enzyme, whereas Edc1 stabilizes the transition state for catalysis. Both activators are required to fully stimulate an autoinhibited Dcp1:Dcp2 as Edc1 alone cannot overcome the decrease in activity attributed to the C-terminal extension. Our data provide a mechanistic framework for combinatorial control of decapping by protein cofactors, a principle that is likely conserved in multiple 5′ mRNA decay pathways.
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Affiliation(s)
- David R Paquette
- Integrative Program in Quantitative Biology, Graduate Group in Biophysics, University of California, San Francisco, CA 94158, USA.,Department of Pharmaceutical Chemistry, University of California, San Francisco, CA 94158, USA
| | - Ryan W Tibble
- Department of Pharmaceutical Chemistry, University of California, San Francisco, CA 94158, USA.,Program in Chemistry and Chemical Biology, University of California, San Francisco, CA 94158, USA
| | - Tristan S Daifuku
- Department of Pharmaceutical Chemistry, University of California, San Francisco, CA 94158, USA
| | - John D Gross
- Integrative Program in Quantitative Biology, Graduate Group in Biophysics, University of California, San Francisco, CA 94158, USA.,Department of Pharmaceutical Chemistry, University of California, San Francisco, CA 94158, USA.,Program in Chemistry and Chemical Biology, University of California, San Francisco, CA 94158, USA
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15
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Nakaminami K, Seki M. RNA Regulation in Plant Cold Stress Response. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1081:23-44. [PMID: 30288702 DOI: 10.1007/978-981-13-1244-1_2] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
In addition to plants, all organisms react to environmental stimuli via the perception of signals and subsequently respond through alterations of gene expression. However, genes/mRNAs are usually not the functional unit themselves, and instead, resultant protein products with individual functions result in various acquired phenotypes. In order to fully characterize the adaptive responses of plants to environmental stimuli, it is essential to determine the level of proteins, in addition to the regulation of mRNA expression. This regulatory step, which is referred to as "mRNA posttranscriptional regulation," occurs subsequent to mRNA transcription and prior to translation. Although these RNA regulatory mechanisms have been well-studied in many organisms, including plants, it is not fully understood how plants respond to environmental stimuli, such as cold stress, via these RNA regulations.A recent study described several RNA regulatory factors in relation to environmental stress responses, including plant cold stress tolerance. In this chapter, the functions of RNA regulatory factors and comprehensive analyses related to the RNA regulations involved in cold stress response are summarized, such as mRNA maturation, including capping, splicing, polyadenylation of mRNA, and the quality control system of mRNA; mRNA degradation, including the decapping step; and mRNA stabilization. In addition, the putative roles of messenger ribonucleoprotein (mRNP) granules, such as processing bodies (PBs) and stress granules (SGs), which are cytoplasmic particles, are described in relation to RNA regulations under stress conditions. These RNA regulatory systems are important for adjusting or fine-tuning and determining the final levels of mRNAs and proteins in order to adapt or respond to environmental stresses. Collectively, these new areas of study revealed that plants possess precise novel regulatory mechanisms which specifically function in the response to cold stress.
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Affiliation(s)
- Kentaro Nakaminami
- Plant Genomic Network Research Team, RIKEN Center for Sustainable Resource Science, Yokohama, Kanagawa, Japan.
| | - Motoaki Seki
- Plant Genomic Network Research Team, RIKEN Center for Sustainable Resource Science, Yokohama, Kanagawa, Japan
- Plant Epigenome Regulation Laboratory, Cluster for Pioneering Research, RIKEN, Wako, Saitama, Japan
- Kihara Institute for Biological Research, Yokohama City University, Yokohama, Kanagawa, Japan
- Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology (JST), Kawaguchi, Saitama, Japan
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16
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He F, Celik A, Wu C, Jacobson A. General decapping activators target different subsets of inefficiently translated mRNAs. eLife 2018; 7:34409. [PMID: 30520724 PMCID: PMC6300357 DOI: 10.7554/elife.34409] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Accepted: 12/04/2018] [Indexed: 12/18/2022] Open
Abstract
The Dcp1-Dcp2 decapping enzyme and the decapping activators Pat1, Dhh1, and Lsm1 regulate mRNA decapping, but their mechanistic integration is unknown. We analyzed the gene expression consequences of deleting PAT1, LSM1, or DHH1, or the DCP2 C-terminal domain, and found that: i) the Dcp2 C-terminal domain is an effector of both negative and positive regulation; ii) rather than being global activators of decapping, Pat1, Lsm1, and Dhh1 directly target specific subsets of yeast mRNAs and loss of the functions of each of these factors has substantial indirect consequences for genome-wide mRNA expression; and iii) transcripts targeted by Pat1, Lsm1, and Dhh1 exhibit only partial overlap, are generally translated inefficiently, and, as expected, are targeted to decapping-dependent decay. Our results define the roles of Pat1, Lsm1, and Dhh1 in decapping of general mRNAs and suggest that these factors may monitor mRNA translation and target unique features of individual mRNAs.
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Affiliation(s)
- Feng He
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Massachusetts, United States
| | - Alper Celik
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Massachusetts, United States
| | - Chan Wu
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Massachusetts, United States
| | - Allan Jacobson
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Massachusetts, United States
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17
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Mugridge JS, Coller J, Gross JD. Structural and molecular mechanisms for the control of eukaryotic 5'-3' mRNA decay. Nat Struct Mol Biol 2018; 25:1077-1085. [PMID: 30518847 DOI: 10.1038/s41594-018-0164-z] [Citation(s) in RCA: 71] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2018] [Accepted: 10/31/2018] [Indexed: 12/15/2022]
Abstract
5'-3' RNA decay pathways are critical for quality control and regulation of gene expression. Structural and biochemical studies have provided insights into the key nucleases that carry out deadenylation, decapping, and exonucleolysis during 5'-3' decay, but detailed understanding of how these activities are coordinated is only beginning to emerge. Here we review recent mechanistic insights into the control of 5'-3' RNA decay, including coupling between translation and decay, coordination between the complexes and activities that process 5' and 3' RNA termini, conformational control of enzymatic activity, liquid phase separation, and RNA modifications.
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Affiliation(s)
- Jeffrey S Mugridge
- Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, CA, USA
| | - Jeff Coller
- The Center for RNA Science and Therapeutics, Case Western Reserve University, Cleveland, OH, USA
| | - John D Gross
- Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, CA, USA.
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18
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Charenton C, Graille M. mRNA decapping: finding the right structures. Philos Trans R Soc Lond B Biol Sci 2018; 373:rstb.2018.0164. [PMID: 30397101 DOI: 10.1098/rstb.2018.0164] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/24/2018] [Indexed: 12/14/2022] Open
Abstract
In eukaryotes, the elimination of the m7GpppN mRNA cap, a process known as decapping, is a critical, largely irreversible and highly regulated step of mRNA decay that withdraws the targeted mRNAs from the pool of translatable templates. The decapping reaction is catalysed by a multi-protein complex formed by the Dcp2 catalytic subunit and its Dcp1 cofactor, a holoenzyme that is poorly active on its own and needs several accessory proteins (Lsm1-7 complex, Pat1, Edc1-2, Edc3 and/or EDC4) to be fully efficient. Here, we discuss the several crystal structures of Dcp2 domains bound to various partners (proteins or small molecules) determined in the last couple of years that have considerably improved our current understanding of how Dcp2, assisted by its various activators, is recruited to its mRNA targets and adopts its active conformation upon substrate recognition. We also describe how, over the years, elegant integrative structural biology approaches combined to biochemistry and genetics led to the identification of the correct structure of the active Dcp1-Dcp2 holoenzyme among the many available conformations trapped by X-ray crystallography.This article is part of the theme issue '5' and 3' modifications controlling RNA degradation'.
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Affiliation(s)
- Clément Charenton
- Laboratoire de Biochimie, Ecole polytechnique, CNRS, Université Paris-Saclay, F-91128 Palaiseau cedex, France
| | - Marc Graille
- Laboratoire de Biochimie, Ecole polytechnique, CNRS, Université Paris-Saclay, F-91128 Palaiseau cedex, France
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19
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Gaviraghi M, Vivori C, Pareja Sanchez Y, Invernizzi F, Cattaneo A, Santoliquido BM, Frenquelli M, Segalla S, Bachi A, Doglioni C, Pelechano V, Cittaro D, Tonon G. Tumor suppressor PNRC1 blocks rRNA maturation by recruiting the decapping complex to the nucleolus. EMBO J 2018; 37:embj.201899179. [PMID: 30373810 DOI: 10.15252/embj.201899179] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Revised: 09/14/2018] [Accepted: 09/19/2018] [Indexed: 12/20/2022] Open
Abstract
Focal deletions occur frequently in the cancer genome. However, the putative tumor-suppressive genes residing within these regions have been difficult to pinpoint. To robustly identify these genes, we implemented a computational approach based on non-negative matrix factorization, NMF, and interrogated the TCGA dataset. This analysis revealed a metagene signature including a small subset of genes showing pervasive hemizygous deletions, reduced expression in cancer patient samples, and nucleolar function. Amid the genes belonging to this signature, we have identified PNRC1, a nuclear receptor coactivator. We found that PNRC1 interacts with the cytoplasmic DCP1α/DCP2 decapping machinery and hauls it inside the nucleolus. PNRC1-dependent nucleolar translocation of the decapping complex is associated with a decrease in the 5'-capped U3 and U8 snoRNA fractions, hampering ribosomal RNA maturation. As a result, PNRC1 ablates the enhanced proliferation triggered by established oncogenes such as RAS and MYC These observations uncover a previously undescribed mechanism of tumor suppression, whereby the cytoplasmic decapping machinery is hauled within nucleoli, tightly regulating ribosomal RNA maturation.
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Affiliation(s)
- Marco Gaviraghi
- Functional Genomics of Cancer Unit, Division of Experimental Oncology, Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) San Raffaele Scientific Institute, Milan, Italy
| | - Claudia Vivori
- Functional Genomics of Cancer Unit, Division of Experimental Oncology, Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) San Raffaele Scientific Institute, Milan, Italy
| | - Yerma Pareja Sanchez
- Science for Life Laboratory, Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Solna, Sweden
| | - Francesca Invernizzi
- Pathology Unit, Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) San Raffaele Scientific Institute, Milan, Italy
| | - Angela Cattaneo
- Functional Proteomics Program, Istituto FIRC di Oncologia Molecolare (IFOM), Milan, Italy
| | - Benedetta Maria Santoliquido
- Functional Genomics of Cancer Unit, Division of Experimental Oncology, Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) San Raffaele Scientific Institute, Milan, Italy
| | - Michela Frenquelli
- Functional Genomics of Cancer Unit, Division of Experimental Oncology, Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) San Raffaele Scientific Institute, Milan, Italy
| | - Simona Segalla
- Functional Genomics of Cancer Unit, Division of Experimental Oncology, Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) San Raffaele Scientific Institute, Milan, Italy
| | - Angela Bachi
- Functional Proteomics Program, Istituto FIRC di Oncologia Molecolare (IFOM), Milan, Italy
| | - Claudio Doglioni
- Pathology Unit, Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) San Raffaele Scientific Institute, Milan, Italy
| | - Vicent Pelechano
- Science for Life Laboratory, Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Solna, Sweden
| | - Davide Cittaro
- Center for Translational Genomics and Bioinformatics, Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) San Raffaele Scientific Institute, Milan, Italy
| | - Giovanni Tonon
- Functional Genomics of Cancer Unit, Division of Experimental Oncology, Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) San Raffaele Scientific Institute, Milan, Italy .,Center for Translational Genomics and Bioinformatics, Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) San Raffaele Scientific Institute, Milan, Italy
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20
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Grzela R, Nasilowska K, Lukaszewicz M, Tyras M, Stepinski J, Jankowska-Anyszka M, Bojarska E, Darzynkiewicz E. Hydrolytic activity of human Nudt16 enzyme on dinucleotide cap analogs and short capped oligonucleotides. RNA (NEW YORK, N.Y.) 2018; 24:633-642. [PMID: 29483298 PMCID: PMC5900562 DOI: 10.1261/rna.065698.118] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Accepted: 02/20/2018] [Indexed: 05/30/2023]
Abstract
Human Nudt16 (hNudt16) is a member of the Nudix family of hydrolases, comprising enzymes catabolizing various substrates including canonical (d)NTPs, oxidized (d)NTPs, nonnucleoside polyphosphates, and capped mRNAs. Decapping activity of the Xenopus laevis (X29) Nudt16 homolog was observed in the nucleolus, with a high specificity toward U8 snoRNA. Subsequent studies have reported cytoplasmic localization of mammalian Nudt16 with cap hydrolysis activity initiating RNA turnover, similar to Dcp2. The present study focuses on hNudt16 and its hydrolytic activity toward dinucleotide cap analogs and short capped oligonucleotides. We performed a screening assay for potential dinucleotide and oligonucleotide substrates for hNudt16. Our data indicate that dinucleotide cap analogs and capped oligonucleotides containing guanine base in the first transcribed nucleotide are more susceptible to enzymatic digestion by hNudt16 than their counterparts containing adenine. Furthermore, unmethylated dinucleotides (GpppG and ApppG) and respective oligonucleotides (GpppG-16nt and GpppA-16nt) were hydrolyzed by hNudt16 with greater efficiency than were m7GpppG and m7GpppG-16nt. In conclusion, we found that hNudt16 hydrolysis of dinucleotide cap analogs and short capped oligonucleotides displayed a broader spectrum specificity than is currently known.
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Affiliation(s)
- Renata Grzela
- Centre of New Technologies, University of Warsaw, 02-097 Warsaw, Poland
| | - Karolina Nasilowska
- Division of Biophysics, Institute of Experimental Physics, Faculty of Physics, University of Warsaw, 02-097 Warsaw, Poland
| | - Maciej Lukaszewicz
- Division of Biophysics, Institute of Experimental Physics, Faculty of Physics, University of Warsaw, 02-097 Warsaw, Poland
| | - Michal Tyras
- Centre of New Technologies, University of Warsaw, 02-097 Warsaw, Poland
| | - Janusz Stepinski
- Centre of New Technologies, University of Warsaw, 02-097 Warsaw, Poland
| | | | - Elzbieta Bojarska
- Centre of New Technologies, University of Warsaw, 02-097 Warsaw, Poland
| | - Edward Darzynkiewicz
- Centre of New Technologies, University of Warsaw, 02-097 Warsaw, Poland
- Division of Biophysics, Institute of Experimental Physics, Faculty of Physics, University of Warsaw, 02-097 Warsaw, Poland
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21
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Mugridge JS, Tibble RW, Ziemniak M, Jemielity J, Gross JD. Structure of the activated Edc1-Dcp1-Dcp2-Edc3 mRNA decapping complex with substrate analog poised for catalysis. Nat Commun 2018; 9:1152. [PMID: 29559651 PMCID: PMC5861098 DOI: 10.1038/s41467-018-03536-x] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2017] [Accepted: 02/22/2018] [Indexed: 11/17/2022] Open
Abstract
The conserved decapping enzyme Dcp2 recognizes and removes the 5′ eukaryotic cap from mRNA transcripts in a critical step of many cellular RNA decay pathways. Dcp2 is a dynamic enzyme that functions in concert with the essential activator Dcp1 and a diverse set of coactivators to selectively and efficiently decap target mRNAs in the cell. Here we present a 2.84 Å crystal structure of K. lactis Dcp1–Dcp2 in complex with coactivators Edc1 and Edc3, and with substrate analog bound to the Dcp2 active site. Our structure shows how Dcp2 recognizes cap substrate in the catalytically active conformation of the enzyme, and how coactivator Edc1 forms a three-way interface that bridges the domains of Dcp2 to consolidate the active conformation. Kinetic data reveal Dcp2 has selectivity for the first transcribed nucleotide during the catalytic step. The heterotetrameric Edc1–Dcp1–Dcp2–Edc3 structure shows how coactivators Edc1 and Edc3 can act simultaneously to activate decapping catalysis. The decapping enzyme Dcp2 removes the 5′ eukaryotic cap from mRNA transcripts and acts in concert with its essential activator Dcp1 and various coactivators. Here the authors present the structure of the fully-activated mRNA decapping complex, which reveals how Dcp2 recognizes the cap substrate and coactivators Edc1 and Edc3 activate catalysis.
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Affiliation(s)
- Jeffrey S Mugridge
- Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, CA, 94158, USA
| | - Ryan W Tibble
- Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, CA, 94158, USA.,Program in Chemistry and Chemical Biology, University of California, San Francisco, San Francisco, CA, 94158, USA
| | - Marcin Ziemniak
- Division of Biophysics, Institute of Experimental Physics, Faculty of Physics, University of Warsaw, 02-089, Warsaw, Poland.,Centre of New Technologies, University of Warsaw, 02-097, Warsaw, Poland.,Biological and Chemical Research Centre, Department of Chemistry, University of Warsaw, 02-089, Warsaw, Poland
| | - Jacek Jemielity
- Centre of New Technologies, University of Warsaw, 02-097, Warsaw, Poland
| | - John D Gross
- Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, CA, 94158, USA. .,Program in Chemistry and Chemical Biology, University of California, San Francisco, San Francisco, CA, 94158, USA.
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22
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Quintas A, Pérez-Núñez D, Sánchez EG, Nogal ML, Hentze MW, Castelló A, Revilla Y. Characterization of the African Swine Fever Virus Decapping Enzyme during Infection. J Virol 2017; 91:e00990-17. [PMID: 29021398 PMCID: PMC5709586 DOI: 10.1128/jvi.00990-17] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2017] [Accepted: 10/03/2017] [Indexed: 01/13/2023] Open
Abstract
African swine fever virus (ASFV) infection is characterized by a progressive decrease in cellular protein synthesis with a concomitant increase in viral protein synthesis, though the mechanism by which the virus achieves this is still unknown. Decrease of cellular mRNA is observed during ASFV infection, suggesting that inhibition of cellular proteins is due to an active mRNA degradation process. ASFV carries a gene (Ba71V D250R/Malawi g5R) that encodes a decapping protein (ASFV-DP) that has a Nudix hydrolase motif and decapping activity in vitro Here, we show that ASFV-DP was expressed from early times and accumulated throughout the infection with a subcellular localization typical of the endoplasmic reticulum, colocalizing with the cap structure and interacting with the ribosomal protein L23a. ASFV-DP was capable of interaction with poly(A) RNA in cultured cells, primarily mediated by the N-terminal region of the protein. ASFV-DP also interacted with viral and cellular RNAs in the context of infection, and its overexpression in infected cells resulted in decreased levels of both types of transcripts. This study points to ASFV-DP as a viral decapping enzyme involved in both the degradation of cellular mRNA and the regulation of viral transcripts.IMPORTANCE Virulent ASFV strains cause a highly infectious and lethal disease in domestic pigs for which there is no vaccine. Since 2007, an outbreak in the Caucasus region has spread to Russia, jeopardizing the European pig population and making it essential to deepen knowledge about the virus. Here, we demonstrate that ASFV-DP is a novel RNA-binding protein implicated in the regulation of mRNA metabolism during infection, making it a good target for vaccine development.
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Affiliation(s)
- Ana Quintas
- Centro de Biología Molecular Severo Ochoa, CSIC-UAM, Universidad Autónoma de Madrid, Madrid, Spain
| | - Daniel Pérez-Núñez
- Centro de Biología Molecular Severo Ochoa, CSIC-UAM, Universidad Autónoma de Madrid, Madrid, Spain
| | - Elena G Sánchez
- Centro de Biología Molecular Severo Ochoa, CSIC-UAM, Universidad Autónoma de Madrid, Madrid, Spain
| | - Maria L Nogal
- Centro de Biología Molecular Severo Ochoa, CSIC-UAM, Universidad Autónoma de Madrid, Madrid, Spain
| | | | - Alfredo Castelló
- European Molecular Biology Laboratory (EMBL), Heidelberg, Germany
- Department of Biochemistry, University of Oxford, Oxford, United Kingdom
| | - Yolanda Revilla
- Centro de Biología Molecular Severo Ochoa, CSIC-UAM, Universidad Autónoma de Madrid, Madrid, Spain
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23
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A unique surface on Pat1 C-terminal domain directly interacts with Dcp2 decapping enzyme and Xrn1 5'-3' mRNA exonuclease in yeast. Proc Natl Acad Sci U S A 2017; 114:E9493-E9501. [PMID: 29078363 DOI: 10.1073/pnas.1711680114] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The Pat1 protein is a central player of eukaryotic mRNA decay that has also been implicated in translational control. It is commonly considered a central platform responsible for the recruitment of several RNA decay factors. We demonstrate here that a yeast-specific C-terminal region from Pat1 interacts with several short motifs, named helical leucine-rich motifs (HLMs), spread in the long C-terminal region of yeast Dcp2 decapping enzyme. Structures of Pat1-HLM complexes reveal the basis for HLM recognition by Pat1. We also identify a HLM present in yeast Xrn1, the main 5'-3' exonuclease involved in mRNA decay. We show further that the ability of yeast Pat1 to bind HLMs is required for efficient growth and normal mRNA decay. Overall, our analyses indicate that yeast Pat1 uses a single binding surface to successively recruit several mRNA decay factors and show that interaction between those factors is highly polymorphic between species.
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24
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Affiliation(s)
- Jeff Coller
- Center for RNA Molecular Biology, Case Western Reserve University, Cleveland, Ohio USA
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25
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Abstract
5’-3’ decay is the major mRNA decay pathway in many eukaryotes, including trypanosomes. After deadenylation, mRNAs are decapped by the nudix hydrolase DCP2 of the decapping complex and finally degraded by the 5’-3’ exoribonuclease. Uniquely, trypanosomes lack homologues to all subunits of the decapping complex, while deadenylation and 5’-3’ degradation are conserved. Here, I show that the parasites use an ApaH-like phosphatase (ALPH1) as their major mRNA decapping enzyme. The protein was recently identified as a novel trypanosome stress granule protein and as involved in mRNA binding. A fraction of ALPH1 co-localises exclusively with the trypanosome 5’-3’ exoribonuclease XRNA to a special granule at the posterior pole of the cell, indicating a connection between the two enzymes. RNAi depletion of ALPH1 is lethal and causes a massive increase in total mRNAs that are deadenylated, but have not yet started 5’-3’ decay. These data suggest that ALPH1 acts downstream of deadenylation and upstream of mRNA degradation, consistent with a function in mRNA decapping. In vitro experiments show that recombinant, N-terminally truncated ALHP1 protein, but not a catalytically inactive mutant, sensitises the capped trypanosome spliced leader RNA to yeast Xrn1, but only if an RNA 5’ polyphosphatase is included. This indicates that the decapping mechanism of ALPH1 differs from the decapping mechanism of Dcp2 by leaving more than one phosphate group at the mRNA’s 5’ end. This is the first reported function of a eukaryotic ApaH-like phosphatase, a bacterial-derived class of enzymes present in all phylogenetic super-groups of the eukaryotic kingdom. The substrates of eukaryotic ApaH-like phosphatases are unknown. However, the substrate of the related bacterial enzyme ApaH, diadenosine tetraphosphate, is highly reminiscent of a eukaryotic mRNA cap. Eukaryotic mRNAs are stabilised by a 5’ cap and one important step in mRNA decay is the removal of this cap by the nudix domain protein Dcp2 of the decapping complex. The decapping complex is highly conserved throughout eukaryotes, with the exception of trypanosomes that lack the entire complex. Here, I show that trypanosomes have evolved to use an ApaH-like phosphatase instead of a nudix domain protein as their major decapping enzyme. This work closes an important gap in the knowledge of trypanosome mRNA metabolism. Moreover, this is the first reported function of an ApaH-like phosphatase, a bacterial derived class of enzymes that are widespread throughout eukaryotes.
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Affiliation(s)
- Susanne Kramer
- Biocenter, University of Würzburg, Am Hubland, Würzburg, Germany
- * E-mail:
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26
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Valkov E, Jonas S, Weichenrieder O. Mille viae in eukaryotic mRNA decapping. Curr Opin Struct Biol 2017; 47:40-51. [PMID: 28591671 DOI: 10.1016/j.sbi.2017.05.009] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2017] [Accepted: 05/22/2017] [Indexed: 12/20/2022]
Abstract
Cellular mRNA levels are regulated via rates of transcription and decay. Since the removal of the mRNA 5'-cap by the decapping enzyme DCP2 is generally an irreversible step towards decay, it requires regulation. Control of DCP2 activity is likely effected by two interdependent means: by conformational control of the DCP2-DCP1 complex, and by assembly control of the decapping network, an array of mutually interacting effector proteins. Here, we compare three recent and conformationally distinct crystal structures of the DCP2-DCP1 decapping complex in the presence of substrate analogs and decapping enhancers and we discuss alternative substrate recognition modes for the catalytic domain of DCP2. Together with structure-based insight into decapping network assembly, we propose that DCP2-mediated decapping follows more than one path.
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Affiliation(s)
- Eugene Valkov
- Department of Biochemistry, Max Planck Institute for Developmental Biology, Spemannstrasse 35, 72076 Tübingen, Germany
| | - Stefanie Jonas
- Institute of Biochemistry, ETH Zürich, Otto-Stern Weg 3, 8093 Zürich, Switzerland.
| | - Oliver Weichenrieder
- Department of Biochemistry, Max Planck Institute for Developmental Biology, Spemannstrasse 35, 72076 Tübingen, Germany.
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27
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Srouji JR, Xu A, Park A, Kirsch JF, Brenner SE. The evolution of function within the Nudix homology clan. Proteins 2017; 85:775-811. [PMID: 27936487 PMCID: PMC5389931 DOI: 10.1002/prot.25223] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Revised: 10/15/2016] [Accepted: 11/28/2016] [Indexed: 01/01/2023]
Abstract
The Nudix homology clan encompasses over 80,000 protein domains from all three domains of life, defined by homology to each other. Proteins with a domain from this clan fall into four general functional classes: pyrophosphohydrolases, isopentenyl diphosphate isomerases (IDIs), adenine/guanine mismatch-specific adenine glycosylases (A/G-specific adenine glycosylases), and nonenzymatic activities such as protein/protein interaction and transcriptional regulation. The largest group, pyrophosphohydrolases, encompasses more than 100 distinct hydrolase specificities. To understand the evolution of this vast number of activities, we assembled and analyzed experimental and structural data for 205 Nudix proteins collected from the literature. We corrected erroneous functions or provided more appropriate descriptions for 53 annotations described in the Gene Ontology Annotation database in this family, and propose 275 new experimentally-based annotations. We manually constructed a structure-guided sequence alignment of 78 Nudix proteins. Using the structural alignment as a seed, we then made an alignment of 347 "select" Nudix homology domains, curated from structurally determined, functionally characterized, or phylogenetically important Nudix domains. Based on our review of Nudix pyrophosphohydrolase structures and specificities, we further analyzed a loop region downstream of the Nudix hydrolase motif previously shown to contact the substrate molecule and possess known functional motifs. This loop region provides a potential structural basis for the functional radiation and evolution of substrate specificity within the hydrolase family. Finally, phylogenetic analyses of the 347 select protein domains and of the complete Nudix homology clan revealed general monophyly with regard to function and a few instances of probable homoplasy. Proteins 2017; 85:775-811. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- John R. Srouji
- Plant and Microbial Biology DepartmentUniversity of CaliforniaBerkeleyCalifornia94720
- Molecular and Cell Biology DepartmentUniversity of CaliforniaBerkeleyCalifornia94720
- Present address: Molecular and Cellular Biology DepartmentHarvard UniversityCambridgeMassachusetts02138
| | - Anting Xu
- Graduate Study in Comparative Biochemistry, University of CaliforniaBerkeleyCalifornia94720
| | - Annsea Park
- Molecular and Cell Biology DepartmentUniversity of CaliforniaBerkeleyCalifornia94720
| | - Jack F. Kirsch
- Molecular and Cell Biology DepartmentUniversity of CaliforniaBerkeleyCalifornia94720
- Graduate Study in Comparative Biochemistry, University of CaliforniaBerkeleyCalifornia94720
| | - Steven E. Brenner
- Plant and Microbial Biology DepartmentUniversity of CaliforniaBerkeleyCalifornia94720
- Molecular and Cell Biology DepartmentUniversity of CaliforniaBerkeleyCalifornia94720
- Graduate Study in Comparative Biochemistry, University of CaliforniaBerkeleyCalifornia94720
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28
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Structural basis of mRNA-cap recognition by Dcp1-Dcp2. Nat Struct Mol Biol 2016; 23:987-994. [PMID: 27694842 PMCID: PMC5113729 DOI: 10.1038/nsmb.3301] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2016] [Accepted: 09/01/2016] [Indexed: 11/21/2022]
Abstract
Removal of the 5′ cap on mRNA by the decapping enzyme Dcp2 is a critical step in 5′-to-3′ mRNA decay. Understanding the structural basis of Dcp2 activity has been a significant challenge because Dcp2 is dynamic, with weak affinity for cap substrate. Here we present a 2.6-Å-resolution crystal structure of a heterotrimer of fission yeast Dcp2, its essential activator Dcp1, and the human NMD cofactor PNRC2, in complex with a tight-binding cap analog. Cap binding is accompanied by a conformational change of Dcp2 to form a composite nucleotide binding site using conserved residues on the catalytic and regulatory domains. Kinetic analysis of PNRC2 reveals a conserved short linear motif enhances both substrate affinity and the catalytic step of decapping. These findings explain why Dcp2 requires a conformational change for efficient catalysis and reveals that coactivators can promote RNA binding and the catalytic step of decapping, possibly through different conformational states.
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29
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Structure of the active form of Dcp1-Dcp2 decapping enzyme bound to m 7GDP and its Edc3 activator. Nat Struct Mol Biol 2016; 23:982-986. [PMID: 27694841 DOI: 10.1038/nsmb.3300] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Accepted: 09/01/2016] [Indexed: 01/19/2023]
Abstract
Elimination of the 5' cap of eukaryotic mRNAs, known as decapping, is considered to be a crucial, irreversible and highly regulated step required for the rapid degradation of mRNA by Xrn1, the major cytoplasmic 5'-3' exonuclease. Decapping is accomplished by the recruitment of a protein complex formed by the Dcp2 catalytic subunit and its Dcp1 cofactor. However, this complex has a low intrinsic enzymatic activity and requires several accessory proteins such as the Lsm1-7 complex, Pat1, Edc1-Edc2 and/or Edc3 to be fully active. Here we present the crystal structure of the active form of the yeast Kluyveromyces lactis Dcp1-Dcp2 enzyme bound to its product (m7GDP) and its potent activator Edc3. This structure of the Dcp1-Dcp2 complex bound to a cap analog further explains previously published data on substrate binding and provides hints as to the mechanism of Edc3-mediated Dcp2 activation.
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30
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Höfer K, Li S, Abele F, Frindert J, Schlotthauer J, Grawenhoff J, Du J, Patel DJ, Jäschke A. Structure and function of the bacterial decapping enzyme NudC. Nat Chem Biol 2016; 12:730-4. [PMID: 27428510 PMCID: PMC5003112 DOI: 10.1038/nchembio.2132] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2016] [Accepted: 05/23/2016] [Indexed: 11/25/2022]
Abstract
RNA capping and decapping are thought to be distinctive features of eukaryotes. The redox cofactor NAD was recently discovered to be attached to small regulatory RNAs in bacteria in a cap-like manner, and Nudix hydrolase NudC was found to act as a NAD-decapping enzyme in vitro and in vivo. Here, crystal structures of Escherichia coli NudC in complex with substrate NAD and with cleavage product NMN reveal the catalytic residues lining the binding pocket and principles underlying molecular recognition of substrate and product. Biochemical mutation analysis identifies the conserved Nudix motif as the catalytic center of the enzyme, which needs to be homodimeric, as the catalytic pocket is composed of amino acids from both monomers. NudC is single-strand specific and has a purine preference for the 5'-terminal nucleotide. The enzyme strongly prefers NAD-linked RNA (NAD-RNA) over NAD and binds to a diverse set of cellular RNAs in an unspecific manner.
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Affiliation(s)
- Katharina Höfer
- Institute of Pharmacy and Molecular Biotechnology, Heidelberg University, 69120 Heidelberg, Germany
| | - Sisi Li
- Structural Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Florian Abele
- Institute of Pharmacy and Molecular Biotechnology, Heidelberg University, 69120 Heidelberg, Germany
| | - Jens Frindert
- Institute of Pharmacy and Molecular Biotechnology, Heidelberg University, 69120 Heidelberg, Germany
| | - Jasmin Schlotthauer
- Institute of Pharmacy and Molecular Biotechnology, Heidelberg University, 69120 Heidelberg, Germany
| | - Julia Grawenhoff
- Institute of Pharmacy and Molecular Biotechnology, Heidelberg University, 69120 Heidelberg, Germany
| | - Jiamu Du
- Shanghai Center for Plant Stress Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 201602, China
| | - Dinshaw J. Patel
- Structural Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Andres Jäschke
- Institute of Pharmacy and Molecular Biotechnology, Heidelberg University, 69120 Heidelberg, Germany
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31
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Wurm JP, Overbeck J, Sprangers R. The S. pombe mRNA decapping complex recruits cofactors and an Edc1-like activator through a single dynamic surface. RNA (NEW YORK, N.Y.) 2016; 22:1360-72. [PMID: 27354705 PMCID: PMC4986892 DOI: 10.1261/rna.057315.116] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2016] [Accepted: 05/22/2016] [Indexed: 05/19/2023]
Abstract
The removal of the 5' 7-methylguanosine mRNA cap structure (decapping) is a central step in the 5'-3' mRNA degradation pathway and is performed by the Dcp1:Dcp2 decapping complex. The activity of this complex is tightly regulated to prevent premature degradation of the transcript. Here, we establish that the aromatic groove of the EVH1 domain of Schizosaccharomyces pombe Dcp1 can interact with proline-rich sequences in the exonuclease Xrn1, the scaffolding protein Pat1, the helicase Dhh1, and the C-terminal disordered region of Dcp2. We show that this region of Dcp1 can also recruit a previously unidentified enhancer of decapping protein (Edc1) and solved the crystal structure of the complex. NMR relaxation dispersion experiments reveal that the Dcp1 binding site can adopt multiple conformations, thus providing the plasticity that is required to accommodate different ligands. We show that the activator Edc1 makes additional contacts with the regulatory domain of Dcp2 and that an activation motif in Edc1 increases the RNA affinity of Dcp1:Dcp2. Our data support a model where Edc1 stabilizes the RNA in the active site, which results in enhanced decapping rates. In summary, we show that multiple decapping factors, including the Dcp2 C-terminal region, compete with Edc1 for Dcp1 binding. Our data thus reveal a network of interactions that can fine-tune the catalytic activity of the decapping complex.
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Affiliation(s)
- Jan Philip Wurm
- Max Planck Institute for Developmental Biology, 72076 Tübingen, Germany
| | - Jan Overbeck
- Max Planck Institute for Developmental Biology, 72076 Tübingen, Germany
| | - Remco Sprangers
- Max Planck Institute for Developmental Biology, 72076 Tübingen, Germany
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32
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Valkov E, Muthukumar S, Chang CT, Jonas S, Weichenrieder O, Izaurralde E. Structure of the Dcp2-Dcp1 mRNA-decapping complex in the activated conformation. Nat Struct Mol Biol 2016; 23:574-9. [PMID: 27183195 DOI: 10.1038/nsmb.3232] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2016] [Accepted: 04/20/2016] [Indexed: 11/09/2022]
Abstract
The removal of the mRNA 5' cap (decapping) by Dcp2 shuts down translation and commits mRNA to full degradation. Dcp2 activity is enhanced by activator proteins such as Dcp1 and Edc1. However, owing to conformational flexibility, the active conformation of Dcp2 and the mechanism of decapping activation have remained unknown. Here, we report a 1.6-Å-resolution crystal structure of the Schizosaccharomyces pombe Dcp2-Dcp1 heterodimer in an unprecedented conformation that is tied together by an intrinsically disordered peptide from Edc1. In this ternary complex, an unforeseen rotation of the Dcp2 catalytic domain allows residues from both Dcp2 and Dcp1 to cooperate in RNA binding, thus explaining decapping activation by increased substrate affinity. The architecture of the Dcp2-Dcp1-Edc1 complex provides a rationale for the conservation of a sequence motif in Edc1 that is also present in unrelated decapping activators, thus indicating that the presently described mechanism of decapping activation is evolutionarily conserved.
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Affiliation(s)
- Eugene Valkov
- Department of Biochemistry, Max Planck Institute for Developmental Biology, Tübingen, Germany
| | - Sowndarya Muthukumar
- Department of Biochemistry, Max Planck Institute for Developmental Biology, Tübingen, Germany
| | - Chung-Te Chang
- Department of Biochemistry, Max Planck Institute for Developmental Biology, Tübingen, Germany
| | - Stefanie Jonas
- Department of Biochemistry, Max Planck Institute for Developmental Biology, Tübingen, Germany
| | - Oliver Weichenrieder
- Department of Biochemistry, Max Planck Institute for Developmental Biology, Tübingen, Germany
| | - Elisa Izaurralde
- Department of Biochemistry, Max Planck Institute for Developmental Biology, Tübingen, Germany
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33
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Ziemniak M, Mugridge JS, Kowalska J, Rhoads RE, Gross JD, Jemielity J. Two-headed tetraphosphate cap analogs are inhibitors of the Dcp1/2 RNA decapping complex. RNA (NEW YORK, N.Y.) 2016; 22:518-29. [PMID: 26826132 PMCID: PMC4793208 DOI: 10.1261/rna.055152.115] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2015] [Accepted: 12/10/2015] [Indexed: 05/08/2023]
Abstract
Dcp1/2 is the major eukaryotic RNA decapping complex, comprised of the enzyme Dcp2 and activator Dcp1, which removes the 5' m(7)G cap from mRNA, committing the transcript to degradation. Dcp1/2 activity is crucial for RNA quality control and turnover, and deregulation of these processes may lead to disease development. The molecular details of Dcp1/2 catalysis remain elusive, in part because both cap substrate (m(7)GpppN) and m(7)GDP product are bound by Dcp1/2 with weak (mM) affinity. In order to find inhibitors to use in elucidating the catalytic mechanism of Dcp2, we screened a small library of synthetic m(7)G nucleotides (cap analogs) bearing modifications in the oligophosphate chain. One of the most potent cap analogs, m(7)GpSpppSm(7)G, inhibited Dcp1/2 20 times more efficiently than m(7)GpppN or m(7)GDP. NMR experiments revealed that the compound interacts with specific surfaces of both regulatory and catalytic domains of Dcp2 with submillimolar affinities. Kinetics analysis revealed that m(7)GpSpppSm(7)G is a mixed inhibitor that competes for the Dcp2 active site with micromolar affinity. m(7)GpSpppSm(7)G-capped RNA undergoes rapid decapping, suggesting that the compound may act as a tightly bound cap mimic. Our identification of the first small molecule inhibitor of Dcp2 should be instrumental in future studies aimed at understanding the structural basis of RNA decapping and may provide insight toward the development of novel therapeutically relevant decapping inhibitors.
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Affiliation(s)
- Marcin Ziemniak
- Division of Biophysics, Institute of Experimental Physics, Faculty of Physics, University of Warsaw, 02-089 Warsaw, Poland
| | - Jeffrey S Mugridge
- Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, California 94158, USA
| | - Joanna Kowalska
- Division of Biophysics, Institute of Experimental Physics, Faculty of Physics, University of Warsaw, 02-089 Warsaw, Poland
| | - Robert E Rhoads
- Department of Biochemistry and Molecular Biology, Louisiana State University Health Sciences Center, Shreveport, Louisiana 71130-3932, USA
| | - John D Gross
- Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, California 94158, USA
| | - Jacek Jemielity
- Centre of New Technologies, University of Warsaw, 02-097 Warsaw, Poland
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Rhoads RE. Synthetic mRNA: Production, Introduction into Cells, and Physiological Consequences. Methods Mol Biol 2016; 1428:3-27. [PMID: 27236789 DOI: 10.1007/978-1-4939-3625-0_1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Recent advances have made it possible to synthesize mRNA in vitro that is relatively stable when introduced into mammalian cells, has a diminished ability to activate the innate immune response against exogenous (virus-like) RNA, and can be efficiently translated into protein. Synthetic methods have also been developed to produce mRNA with unique investigational properties such as photo-cross-linking, fluorescence emission, and attachment of ligands through click chemistry. Synthetic mRNA has been proven effective in numerous applications beneficial for human health such as immunizing patients against cancer and infections diseases, alleviating diseases by restoring deficient proteins, converting somatic cells to pluripotent stem cells to use in regenerative medicine therapies, and engineering the genome by making specific alterations in DNA. This introductory chapter provides background information relevant to the following 20 chapters of this volume that present protocols for these applications of synthetic mRNA.
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Affiliation(s)
- Robert E Rhoads
- Department of Biochemistry and Molecular Biology, Louisiana State University Health Sciences Center, Shreveport, LA, 71130-3932, USA.
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35
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Milias-Argeitis A, Engblom S, Bauer P, Khammash M. Stochastic focusing coupled with negative feedback enables robust regulation in biochemical reaction networks. J R Soc Interface 2015; 12:20150831. [PMID: 26609065 PMCID: PMC4707857 DOI: 10.1098/rsif.2015.0831] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2015] [Accepted: 11/05/2015] [Indexed: 12/16/2022] Open
Abstract
Nature presents multiple intriguing examples of processes that proceed with high precision and regularity. This remarkable stability is frequently counter to modellers' experience with the inherent stochasticity of chemical reactions in the regime of low-copy numbers. Moreover, the effects of noise and nonlinearities can lead to 'counterintuitive' behaviour, as demonstrated for a basic enzymatic reaction scheme that can display stochastic focusing (SF). Under the assumption of rapid signal fluctuations, SF has been shown to convert a graded response into a threshold mechanism, thus attenuating the detrimental effects of signal noise. However, when the rapid fluctuation assumption is violated, this gain in sensitivity is generally obtained at the cost of very large product variance, and this unpredictable behaviour may be one possible explanation of why, more than a decade after its introduction, SF has still not been observed in real biochemical systems. In this work, we explore the noise properties of a simple enzymatic reaction mechanism with a small and fluctuating number of active enzymes that behaves as a high-gain, noisy amplifier due to SF caused by slow enzyme fluctuations. We then show that the inclusion of a plausible negative feedback mechanism turns the system from a noisy signal detector to a strong homeostatic mechanism by exchanging high gain with strong attenuation in output noise and robustness to parameter variations. Moreover, we observe that the discrepancy between deterministic and stochastic descriptions of stochastically focused systems in the evolution of the means almost completely disappears, despite very low molecule counts and the additional nonlinearity due to feedback. The reaction mechanism considered here can provide a possible resolution to the apparent conflict between intrinsic noise and high precision in critical intracellular processes.
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Affiliation(s)
- Andreas Milias-Argeitis
- Department of Biosystems Science and Engineering, ETH Zurich, Mattenstrasse 26, 4058 Basel, Switzerland
| | - Stefan Engblom
- Division of Scientific Computing, Department of Information Technology, Uppsala University, PO Box 337, 75105 Uppsala, Sweden
| | - Pavol Bauer
- Division of Scientific Computing, Department of Information Technology, Uppsala University, PO Box 337, 75105 Uppsala, Sweden
| | - Mustafa Khammash
- Department of Biosystems Science and Engineering, ETH Zurich, Mattenstrasse 26, 4058 Basel, Switzerland
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36
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He F, Jacobson A. Control of mRNA decapping by positive and negative regulatory elements in the Dcp2 C-terminal domain. RNA (NEW YORK, N.Y.) 2015; 21:1633-47. [PMID: 26184073 PMCID: PMC4536323 DOI: 10.1261/rna.052449.115] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2015] [Accepted: 06/08/2015] [Indexed: 05/23/2023]
Abstract
Decapping commits an mRNA to complete degradation and promotes general 5' to 3' decay, nonsense-mediated decay (NMD), and transcript-specific degradation. In Saccharomyces cerevisiae, a single decapping enzyme composed of a regulatory subunit (Dcp1) and a catalytic subunit (Dcp2) targets thousands of distinct substrate mRNAs. However, the mechanisms controlling this enzyme's in vivo activity and substrate specificity remain elusive. Here, using a genetic approach, we show that the large C-terminal domain of Dcp2 includes a set of conserved negative and positive regulatory elements. A single negative element inhibits enzymatic activity and controls the downstream functions of several positive elements. The positive elements recruit the specific decapping activators Edc3, Pat1, and Upf1 to form distinct decapping complexes and control the enzyme's substrate specificity and final activation. Our results reveal unforeseen regulatory mechanisms that control decapping enzyme activity and function in vivo, and define roles for several decapping activators in the regulation of mRNA decapping.
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Affiliation(s)
- Feng He
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, Massachusetts 01655, USA
| | - Allan Jacobson
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, Massachusetts 01655, USA
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37
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Shi C, Wang S, Zhou T, Jiang Y. Post-transcriptional regulation tends to attenuate the mRNA noise and to increase the mRNA gain. Phys Biol 2015; 12:056002. [PMID: 26266661 DOI: 10.1088/1478-3975/12/5/056002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Post-transcriptional regulation is ubiquitous in prokaryotic and eukaryotic cells, but how it impacts gene expression remains to be fully explored. Here, we analyze a simple gene model in which we assume that mRNAs are produced in a constitutive manner but are regulated post-transcriptionally by a decapping enzyme that switches between the active state and the inactive state. We derive the analytical mRNA distribution governed by a chemical master equation, which can be well used to analyze the mechanism of how post-transcription regulation influences the mRNA expression level including the mRNA noise. We demonstrate that the mean mRNA level in the stochastic case is always higher than that in the deterministic case due to the stochastic effect of the enzyme, but the size of the increased part depends mainly on the switching rates between two enzyme states. More interesting is that we find that in contrast to transcriptional regulation, post-transcriptional regulation tends to attenuate noise in mRNA. Our results provide insight into the role of post-transcriptional regulation in controlling the transcriptional noise.
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Affiliation(s)
- Changhong Shi
- School of Public Health, Guangzhou Medical University, Guangzhou, People's Republic of China
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38
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Steffens A, Bräutigam A, Jakoby M, Hülskamp M. The BEACH Domain Protein SPIRRIG Is Essential for Arabidopsis Salt Stress Tolerance and Functions as a Regulator of Transcript Stabilization and Localization. PLoS Biol 2015; 13:e1002188. [PMID: 26133670 PMCID: PMC4489804 DOI: 10.1371/journal.pbio.1002188] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2014] [Accepted: 05/26/2015] [Indexed: 12/22/2022] Open
Abstract
Members of the highly conserved class of BEACH domain containing proteins (BDCPs) have been established as broad facilitators of protein-protein interactions and membrane dynamics in the context of human diseases like albinism, bleeding diathesis, impaired cellular immunity, cancer predisposition, and neurological dysfunctions. Also, the Arabidopsis thaliana BDCP SPIRRIG (SPI) is important for membrane integrity, as spi mutants exhibit split vacuoles. In this work, we report a novel molecular function of the BDCP SPI in ribonucleoprotein particle formation. We show that SPI interacts with the P-body core component DECAPPING PROTEIN 1 (DCP1), associates to mRNA processing bodies (P-bodies), and regulates their assembly upon salt stress. The finding that spi mutants exhibit salt hypersensitivity suggests that the local function of SPI at P-bodies is of biological relevance. Transcriptome-wide analysis revealed qualitative differences in the salt stress-regulated transcriptional response of Col-0 and spi. We show that SPI regulates the salt stress-dependent post-transcriptional stabilization, cytoplasmic agglomeration, and localization to P-bodies of a subset of salt stress-regulated mRNAs. Finally, we show that the PH-BEACH domains of SPI and its human homolog FAN (Factor Associated with Neutral sphingomyelinase activation) interact with DCP1 isoforms from plants, mammals, and yeast, suggesting the evolutionary conservation of an association of BDCPs and P-bodies.
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Affiliation(s)
| | - Andrea Bräutigam
- Institute of Plant Biochemistry, Cluster of Excellence on Plant Sciences (CEPLAS), Heinrich Heine University, Düsseldorf, Germany
- Plant Biochemistry, Heinrich Heine University, Düsseldorf, Germany
| | - Marc Jakoby
- Botanical Institute, Biocenter, Cologne University, Cologne, Germany
| | - Martin Hülskamp
- Botanical Institute, Biocenter, Cologne University, Cologne, Germany
- * E-mail:
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39
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Competition between Decapping Complex Formation and Ubiquitin-Mediated Proteasomal Degradation Controls Human Dcp2 Decapping Activity. Mol Cell Biol 2015; 35:2144-53. [PMID: 25870104 DOI: 10.1128/mcb.01517-14] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2014] [Accepted: 04/02/2015] [Indexed: 12/28/2022] Open
Abstract
mRNA decapping is a central step in eukaryotic mRNA decay that simultaneously shuts down translation initiation and activates mRNA degradation. A major complex responsible for decapping consists of the decapping enzyme Dcp2 in association with decapping enhancers. An important question is how the activity and accumulation of Dcp2 are regulated at the cellular level to ensure the specificity and fidelity of the Dcp2 decapping complex. Here, we show that human Dcp2 levels and activity are controlled by a competition between decapping complex assembly and Dcp2 degradation. This is mediated by a regulatory domain in the Dcp2 C terminus, which, on the one hand, promotes Dcp2 activation via decapping complex formation mediated by the decapping enhancer Hedls and, on the other hand, targets Dcp2 for ubiquitin-mediated proteasomal degradation in the absence of Hedls association. This competition between Dcp2 activation and degradation restricts the accumulation and activity of uncomplexed Dcp2, which may be important for preventing uncontrolled decapping or for regulating Dcp2 levels and activity according to cellular needs.
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40
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Motomura K, Le QTN, Hamada T, Kutsuna N, Mano S, Nishimura M, Watanabe Y. Diffuse decapping enzyme DCP2 accumulates in DCP1 foci under heat stress in Arabidopsis thaliana. PLANT & CELL PHYSIOLOGY 2015; 56:107-15. [PMID: 25339350 DOI: 10.1093/pcp/pcu151] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
The decapping enzymes DCP1 and DCP2 are components of a decapping complex that degrades mRNAs. DCP2 is the catalytic core and DCP1 is an auxiliary subunit. It has been assumed that DCP1 and DCP2 are consistently co-localized in cytoplasmic RNA granules called processing bodies (P-bodies). However, it has not been confirmed whether DCP1 and DCP2 co-localize in Arabidopsis thaliana. In this study, we generated DCP1-green fluorescent protein (GFP) and DCP2-GFP transgenic plants that complemented dcp1 and dcp2 mutants, respectively, to see whether localization of DCP2 is identical to that of DCP1. DCP2 was present throughout the cytoplasm, whereas DCP1 formed P-body-like foci. Use of DCP1-GFP/DCP2-red fluorescent protein (RFP) or DCP1-RFP/DCP2-GFP plants showed that heat treatment induced DCP2 assembly into DCP1 foci. In contrast, cold treatment did not induce DCP2 assembly, while the number of DCP1 foci increased. These changes in DCP1 and DCP2 localization during heat and cold treatments occurred without changes in DCP1 and DCP2 protein abundance. Our results show that DCP1 and DCP2 respond differently to environmental changes, indicating that P-bodies have diverse DCP1 and DCP2 proportions depending on environmental conditions. The localization changes of DCP1 and DCP2 may explain how specific mRNAs are degraded during changes in environmental conditions.
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Affiliation(s)
- Kazuki Motomura
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Tokyo, 153-8902 Japan
| | - Quy T N Le
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Tokyo, 153-8902 Japan
| | - Takahiro Hamada
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Tokyo, 153-8902 Japan
| | - Natsumaro Kutsuna
- Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo, Chiba, 277-8562 Japan
| | - Shoji Mano
- Department of Cell Biology, National Institute for Basic Biology, Okazaki, 444-8585 Japan Department of Basic Biology, School of Life Science, The Graduate University for Advanced Studies, Okazaki, 444-8585 Japan
| | - Mikio Nishimura
- Department of Cell Biology, National Institute for Basic Biology, Okazaki, 444-8585 Japan Department of Basic Biology, School of Life Science, The Graduate University for Advanced Studies, Okazaki, 444-8585 Japan
| | - Yuichiro Watanabe
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Tokyo, 153-8902 Japan
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41
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Fromm SA, Kamenz J, Nöldeke ER, Neu A, Zocher G, Sprangers R. In‐vitro‐Rekonstitution eines zellulären Phasenübergangs unter Beteiligung der mRNA‐Decapping‐Maschinerie. Angew Chem Int Ed Engl 2014. [DOI: 10.1002/ange.201402885] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Simon A. Fromm
- Max‐Planck‐Institut für Entwicklungsbiologie, Spemannstraße 35, 72076 Tübingen (Deutschland)
| | - Julia Kamenz
- Friedrich‐Miescher‐Laboratorium der Max‐Planck‐Gesellschaft, Tübingen (Deutschland)
| | - Erik R. Nöldeke
- Max‐Planck‐Institut für Entwicklungsbiologie, Spemannstraße 35, 72076 Tübingen (Deutschland)
| | - Ancilla Neu
- Max‐Planck‐Institut für Entwicklungsbiologie, Spemannstraße 35, 72076 Tübingen (Deutschland)
| | - Georg Zocher
- Interfakultäres Institut für Biochemie, Universität Tübingen (Deutschland)
| | - Remco Sprangers
- Max‐Planck‐Institut für Entwicklungsbiologie, Spemannstraße 35, 72076 Tübingen (Deutschland)
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42
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Fromm SA, Kamenz J, Nöldeke ER, Neu A, Zocher G, Sprangers R. In vitro reconstitution of a cellular phase-transition process that involves the mRNA decapping machinery. Angew Chem Int Ed Engl 2014; 53:7354-9. [PMID: 24862735 PMCID: PMC4320757 DOI: 10.1002/anie.201402885] [Citation(s) in RCA: 83] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2014] [Indexed: 12/12/2022]
Abstract
In eukaryotic cells, components of the 5' to 3' mRNA degradation machinery can undergo a rapid phase transition. The resulting cytoplasmic foci are referred to as processing bodies (P-bodies). The molecular details of the self-aggregation process are, however, largely undetermined. Herein, we use a bottom-up approach that combines NMR spectroscopy, isothermal titration calorimetry, X-ray crystallography, and fluorescence microscopy to probe if mRNA degradation factors can undergo phase transitions in vitro. We show that the Schizosaccharomyces pombe Dcp2 mRNA decapping enzyme, its prime activator Dcp1, and the scaffolding proteins Edc3 and Pdc1 are sufficient to reconstitute a phase-separation process. Intermolecular interactions between the Edc3 LSm domain and at least 10 helical leucine-rich motifs in Dcp2 and Pdc1 build the core of the interaction network. We show that blocking of these interactions interferes with the clustering behavior, both in vitro and in vivo.
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Affiliation(s)
- Simon A Fromm
- Max Planck Institute for Developmental BiologySpemannstrasse 35, 72076 Tübingen (Germany)
| | - Julia Kamenz
- Friedrich Miescher Laboratory of the Max Planck SocietyTübingen (Germany)
| | - Erik R Nöldeke
- Max Planck Institute for Developmental BiologySpemannstrasse 35, 72076 Tübingen (Germany)
| | - Ancilla Neu
- Max Planck Institute for Developmental BiologySpemannstrasse 35, 72076 Tübingen (Germany)
| | - Georg Zocher
- Interfaculty Institute of Biochemistry, University of TübingenTübingen (Germany)
| | - Remco Sprangers
- Max Planck Institute for Developmental BiologySpemannstrasse 35, 72076 Tübingen (Germany)
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43
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Chang CT, Bercovich N, Loh B, Jonas S, Izaurralde E. The activation of the decapping enzyme DCP2 by DCP1 occurs on the EDC4 scaffold and involves a conserved loop in DCP1. Nucleic Acids Res 2014; 42:5217-33. [PMID: 24510189 PMCID: PMC4005699 DOI: 10.1093/nar/gku129] [Citation(s) in RCA: 81] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
The removal of the 5′-cap structure by the decapping enzyme DCP2 and its coactivator DCP1 shuts down translation and exposes the mRNA to 5′-to-3′ exonucleolytic degradation by XRN1. Although yeast DCP1 and DCP2 directly interact, an additional factor, EDC4, promotes DCP1–DCP2 association in metazoan. Here, we elucidate how the human proteins interact to assemble an active decapping complex and how decapped mRNAs are handed over to XRN1. We show that EDC4 serves as a scaffold for complex assembly, providing binding sites for DCP1, DCP2 and XRN1. DCP2 and XRN1 bind simultaneously to the EDC4 C-terminal domain through short linear motifs (SLiMs). Additionally, DCP1 and DCP2 form direct but weak interactions that are facilitated by EDC4. Mutational and functional studies indicate that the docking of DCP1 and DCP2 on the EDC4 scaffold is a critical step for mRNA decapping in vivo. They also revealed a crucial role for a conserved asparagine–arginine containing loop (the NR-loop) in the DCP1 EVH1 domain in DCP2 activation. Our data indicate that DCP2 activation by DCP1 occurs preferentially on the EDC4 scaffold, which may serve to couple DCP2 activation by DCP1 with 5′-to-3′ mRNA degradation by XRN1 in human cells.
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Affiliation(s)
- Chung-Te Chang
- Department of Biochemistry, Max Planck Institute for Developmental Biology, Spemannstrasse 35, 72076 Tübingen, Germany
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Jonas S, Izaurralde E. The role of disordered protein regions in the assembly of decapping complexes and RNP granules. Genes Dev 2014; 27:2628-41. [PMID: 24352420 PMCID: PMC3877753 DOI: 10.1101/gad.227843.113] [Citation(s) in RCA: 146] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Removal of the 5′ cap structure is a critical step in mRNA turnover, yet key questions regarding the assembly and regulation of decapping complexes remain unanswered. This review provides comprehensive insight into the structural and biochemical properties of decapping factors. Jonas and Izaurralde highlight the plasticity of the decapping network and cover recent advances that reveal how short linear motifs (SliMs) in disordered regions help maintain interactions between decapping network members. The removal of the 5′ cap structure by the decapping enzyme DCP2 inhibits translation and generally commits the mRNA to irreversible 5′-to-3′ exonucleolytic degradation by XRN1. DCP2 catalytic activity is stimulated by DCP1, and these proteins form the conserved core of the decapping complex. Additional decapping factors orchestrate the recruitment and activity of this complex in vivo. These factors include enhancer of decapping 3 (EDC3), EDC4, like Sm14A (LSm14A), Pat, the LSm1–7 complex, and the RNA helicase DDX6. Decapping factors are often modular and feature folded domains flanked or connected by low-complexity disordered regions. Recent studies have made important advances in understanding how these disordered regions contribute to the assembly of decapping complexes and promote phase transitions that drive RNP granule formation. These studies have also revealed that the decapping network is governed by interactions mediated by short linear motifs (SLiMs) in these disordered regions. Consequently, the network has rapidly evolved, and although decapping factors are conserved, individual interactions between orthologs have been rewired during evolution. The plasticity of the network facilitates the acquisition of additional subunits or domains in pre-existing subunits, enhances opportunities for regulating mRNA degradation, and eventually leads to the emergence of novel functions.
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Affiliation(s)
- Stefanie Jonas
- Department of Biochemistry, Max Planck Institute for Developmental Biology, 72076 Tübingen, Germany
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Dougherty JD, Reineke LC, Lloyd RE. mRNA decapping enzyme 1a (Dcp1a)-induced translational arrest through protein kinase R (PKR) activation requires the N-terminal enabled vasodilator-stimulated protein homology 1 (EVH1) domain. J Biol Chem 2013; 289:3936-49. [PMID: 24382890 DOI: 10.1074/jbc.m113.518191] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We have shown previously that poliovirus infection disrupts cytoplasmic P-bodies in infected mammalian cells. During the infectious cycle, poliovirus causes the directed cleavage of Dcp1a and Pan3, coincident with the dispersion of P-bodies. We now show that expression of Dcp1a prior to infection, surprisingly, restricts poliovirus infection. This inhibition of infection was independent of P-body formation because expression of GFP-Dcp1a mutants that cannot enter P-bodies restricted poliovirus infection similar to wild-type GFP-Dcp1a. Expression of wild-type or mutant GFP-Dcp1a induced phosphorylation of eIF2α through the eIF2α kinase protein kinase R (PKR). Activation of PKR required the amino-terminal EVH1 domain of Dcp1a. This PKR-induced translational inhibition appears to be specific to Dcp1a because the expression of other P-body components, Pan2, Pan3, Ccr4, or Caf1, did not result in the inhibition of poliovirus gene expression or induce eIF2α phosphorylation. The translation blockade induced by Dcp1a expression suggests novel signaling linking RNA degradation/decapping and regulation of translation.
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Affiliation(s)
- Jonathan D Dougherty
- From the Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas 77030
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Lsm2 and Lsm3 bridge the interaction of the Lsm1-7 complex with Pat1 for decapping activation. Cell Res 2013; 24:233-46. [PMID: 24247251 PMCID: PMC3915908 DOI: 10.1038/cr.2013.152] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2013] [Revised: 09/16/2013] [Accepted: 09/28/2013] [Indexed: 02/07/2023] Open
Abstract
The evolutionarily conserved Lsm1-7-Pat1 complex is the most critical activator of mRNA decapping in eukaryotic cells and plays many roles in normal decay, AU-rich element-mediated decay, and miRNA silencing, yet how Pat1 interacts with the Lsm1-7 complex is unknown. Here, we show that Lsm2 and Lsm3 bridge the interaction between the C-terminus of Pat1 (Pat1C) and the Lsm1-7 complex. The Lsm2-3-Pat1C complex and the Lsm1-7-Pat1C complex stimulate decapping in vitro to a similar extent and exhibit similar RNA-binding preference. The crystal structure of the Lsm2-3-Pat1C complex shows that Pat1C binds to Lsm2-3 to form an asymmetric complex with three Pat1C molecules surrounding a heptameric ring formed by Lsm2-3. Structure-based mutagenesis revealed the importance of Lsm2-3-Pat1C interactions in decapping activation in vivo. Based on the structure of Lsm2-3-Pat1C, a model of Lsm1-7-Pat1 complex is constructed and how RNA binds to this complex is discussed.
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Abstract
Cap analogs are chemically modified derivatives of the unique cap structure present at the 5´ end of all eukaryotic mRNAs and several non-coding RNAs. Until recently, cap analogs have served primarily as tools in the study of RNA metabolism. Continuing advances in our understanding of cap biological functions (including RNA stabilization, pre-mRNA splicing, initiation of mRNA translation, as well as cellular transport of mRNAs and snRNAs) and the consequences of the disruption of these processes - resulting in serious medical disorders - have opened new possibilities for pharmaceutical applications of these compounds. In this review, the medicinal potential of cap analogs in areas, such as cancer treatment (including eIF4E targeting and mRNA-based immunotherapy), spinal muscular atrophy treatment, antiviral therapy and the improvement of the localization of nucleus-targeting drugs, are highlighted. Advances achieved to date, challenges, plausible solutions and prospects for the future development of cap analog-based drug design are described.
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Aglietti RA, Floor SN, McClendon CL, Jacobson MP, Gross JD. Active site conformational dynamics are coupled to catalysis in the mRNA decapping enzyme Dcp2. Structure 2013; 21:1571-80. [PMID: 23911090 DOI: 10.1016/j.str.2013.06.021] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2013] [Revised: 06/22/2013] [Accepted: 06/25/2013] [Indexed: 11/16/2022]
Abstract
Removal of the 5' cap structure by Dcp2 is a major step in several 5'-3' mRNA decay pathways. The activity of Dcp2 is enhanced by Dcp1 and bound coactivators, yet the details of how these interactions are linked to chemistry are poorly understood. Here, we report three crystal structures of the catalytic Nudix hydrolase domain of Dcp2 that demonstrate binding of a catalytically essential metal ion, and enzyme kinetics are used to identify several key active site residues involved in acid/base chemistry of decapping. Using nuclear magnetic resonance and molecular dynamics, we find that a conserved metal binding loop on the catalytic domain undergoes conformational changes during the catalytic cycle. These findings describe key events during the chemical step of decapping, suggest local active site conformational changes are important for activity, and provide a framework to explain stimulation of catalysis by the regulatory domain of Dcp2 and associated coactivators.
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Affiliation(s)
- Robin A Aglietti
- Program in Chemistry and Chemical Biology, University of California, San Francisco, San Francisco, CA 94158, USA; Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, CA 94158, USA
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Grudzien-Nogalska E, Kowalska J, Su W, Kuhn AN, Slepenkov SV, Darzynkiewicz E, Sahin U, Jemielity J, Rhoads RE. Synthetic mRNAs with superior translation and stability properties. Methods Mol Biol 2013; 969:55-72. [PMID: 23296927 DOI: 10.1007/978-1-62703-260-5_4] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The translational efficiency and stability of synthetic mRNA in both cultured cells and whole animals can be improved by incorporation of modified cap structures at the 5'-end. mRNAs are synthesized in vitro by a phage RNA polymerase transcribing a plasmid containing the mRNA sequence in the presence of all four NTPs plus a cap dinucleotide. Modifications in the cap dinucleotide at the 2'- or 3'-positions of m(7)Guo, or modifications in the polyphosphate chain, can improve both translational efficiency and stability of the mRNA, thereby increasing the amount and duration of protein expression. In the context of RNA-based immunotherapy, the latter is especially important for antigen production and presentation by dendritic cells. Protocols are presented for synthesis of modified mRNAs, their introduction into cells and whole animals, and measurement of their translational efficiency and stability.
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Affiliation(s)
- Ewa Grudzien-Nogalska
- Department of Biochemistry and Molecular Biology, Lousisiana State University Health Sciences Center, Shreveport, LA, USA
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