1
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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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2
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Khan AH, Bagley JR, LaPierre N, Gonzalez-Figueroa C, Spencer TC, Choudhury M, Xiao X, Eskin E, Jentsch JD, Smith DJ. Genetic pathways regulating the longitudinal acquisition of cocaine self-administration in a panel of inbred and recombinant inbred mice. Cell Rep 2023; 42:112856. [PMID: 37481717 PMCID: PMC10530068 DOI: 10.1016/j.celrep.2023.112856] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Revised: 06/06/2023] [Accepted: 07/10/2023] [Indexed: 07/25/2023] Open
Abstract
To identify addiction genes, we evaluate intravenous self-administration of cocaine or saline in 84 inbred and recombinant inbred mouse strains over 10 days. We integrate the behavior data with brain RNA-seq data from 41 strains. The self-administration of cocaine and that of saline are genetically distinct. We maximize power to map loci for cocaine intake by using a linear mixed model to account for this longitudinal phenotype while correcting for population structure. A total of 15 unique significant loci are identified in the genome-wide association study. A transcriptome-wide association study highlights the Trpv2 ion channel as a key locus for cocaine self-administration as well as identifying 17 additional genes, including Arhgef26, Slc18b1, and Slco5a1. We find numerous instances where alternate splice site selection or RNA editing altered transcript abundance. Our work emphasizes the importance of Trpv2, an ionotropic cannabinoid receptor, for the response to cocaine.
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Affiliation(s)
- Arshad H Khan
- Department of Molecular and Medical Pharmacology, Geffen School of Medicine, UCLA, Los Angeles, CA 90095, USA
| | - Jared R Bagley
- Department of Psychology, Binghamton University, Binghamton, NY, USA
| | - Nathan LaPierre
- Department of Computer Science, UCLA, Los Angeles, CA 90095, USA
| | | | - Tadeo C Spencer
- Department of Integrative Biology and Physiology, UCLA, Los Angeles, CA 90095, USA
| | - Mudra Choudhury
- Department of Integrative Biology and Physiology, UCLA, Los Angeles, CA 90095, USA
| | - Xinshu Xiao
- Department of Integrative Biology and Physiology, UCLA, Los Angeles, CA 90095, USA
| | - Eleazar Eskin
- Department of Computational Medicine, UCLA, Los Angeles, CA 90095, USA
| | - James D Jentsch
- Department of Psychology, Binghamton University, Binghamton, NY, USA
| | - Desmond J Smith
- Department of Molecular and Medical Pharmacology, Geffen School of Medicine, UCLA, Los Angeles, CA 90095, USA.
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3
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Wang Z, Qi H, Zhang Y, Sun H, Dong J, Wang H. PLPP2: Potential therapeutic target of breast cancer in PLPP family. Immunobiology 2022; 227:152298. [DOI: 10.1016/j.imbio.2022.152298] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Revised: 10/10/2022] [Accepted: 10/21/2022] [Indexed: 11/05/2022]
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4
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Park J, Hong J, Seok J, Hong H, Seo H, Kim KJ. Structural studies of a novel auxiliary-domain-containing phenylalanine hydroxylase from Bacillus cereus ATCC 14579. Acta Crystallogr D Struct Biol 2022; 78:586-598. [DOI: 10.1107/s2059798322002674] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2021] [Accepted: 03/08/2022] [Indexed: 11/11/2022] Open
Abstract
Phenylalanine hydroxylase (PAH), which belongs to the aromatic amino-acid hydroxylase family, is involved in protein synthesis and pyomelanine production through the hydroxylation of phenylalanine to tyrosine. In this study, the crystal structure of PAH from Bacillus cereus ATCC 14579 (BcPAH) with an additional 280 amino acids in the C-terminal region was determined. The structure of BcPAH consists of three distinct domains: a core domain with two additional inserted α-helices and two novel auxiliary domains: BcPAH-AD1 and BcPAH-AD2. Structural homologues of BcPAH-AD1 and BcPAH-AD2 are known to be involved in mRNA regulation and protein–protein interactions, and thus it was speculated that BcPAH might utilize the auxiliary domains for interaction with its partner proteins. Furthermore, phylogenetic tree analysis revealed that the three-domain PAHs, including BcPAH, are completely distinctive from both conventional prokaryotic PAHs and eukaryotic PAHs. Finally, biochemical studies of BcPAH showed that BcPAH-AD1 might be important for the structural integrity of the enzyme and that BcPAH-AD2 is related to enzyme stability and/or activity. Investigations into the intracellular functions of the two auxiliary domains and the relationship between these functions and the activity of PAH are required.
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5
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Lekontseva NV, Stolboushkina EA, Nikulin AD. Diversity of LSM Family Proteins: Similarities and Differences. BIOCHEMISTRY (MOSCOW) 2021; 86:S38-S49. [PMID: 33827399 DOI: 10.1134/s0006297921140042] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Members of the Lsm protein family are found in all three domains of life: bacteria, archaea, and eukarya. They are involved in numerous processes associated with RNA processing and gene expression regulation. A common structural feature of all Lsm family proteins is the presence of the Sm fold consisting of a five-stranded β-sheet and an α-helix at the N-terminus. Heteroheptameric eukaryotic Sm and Lsm proteins participate in the formation of spliceosomes and mRNA decapping. Homohexameric bacterial Lsm protein, Hfq, is involved in the regulation of transcription of different mRNAs by facilitating their interactions with small regulatory RNAs. Furthermore, recently obtained data indicate a new role of Hfq as a ribosome biogenesis factor, as it mediates formation of the productive structure of the 17S rRNA 3'- and 5'-sequences, facilitating their further processing by RNases. Lsm archaeal proteins (SmAPs) form homoheptamers and likely interact with single-stranded uridine-rich RNA elements, although the role of these proteins in archaea is still poorly understood. In this review, we discuss the structural features of the Lsm family proteins from different life domains and their structure-function relationships.
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Affiliation(s)
- Natalia V Lekontseva
- Institute of Protein Research, Russian Academy of Sciences, Pushchino, Moscow Region, 142290, Russia.
| | - Elena A Stolboushkina
- Institute of Protein Research, Russian Academy of Sciences, Pushchino, Moscow Region, 142290, Russia
| | - Alexey D Nikulin
- Institute of Protein Research, Russian Academy of Sciences, Pushchino, Moscow Region, 142290, Russia
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6
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Montemayor EJ, Virta JM, Hayes SM, Nomura Y, Brow DA, Butcher SE. Molecular basis for the distinct cellular functions of the Lsm1-7 and Lsm2-8 complexes. RNA (NEW YORK, N.Y.) 2020; 26:1400-1413. [PMID: 32518066 PMCID: PMC7491322 DOI: 10.1261/rna.075879.120] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2020] [Accepted: 06/03/2020] [Indexed: 05/04/2023]
Abstract
Eukaryotes possess eight highly conserved Lsm (like Sm) proteins that assemble into circular, heteroheptameric complexes, bind RNA, and direct a diverse range of biological processes. Among the many essential functions of Lsm proteins, the cytoplasmic Lsm1-7 complex initiates mRNA decay, while the nuclear Lsm2-8 complex acts as a chaperone for U6 spliceosomal RNA. It has been unclear how these complexes perform their distinct functions while differing by only one out of seven subunits. Here, we elucidate the molecular basis for Lsm-RNA recognition and present four high-resolution structures of Lsm complexes bound to RNAs. The structures of Lsm2-8 bound to RNA identify the unique 2',3' cyclic phosphate end of U6 as a prime determinant of specificity. In contrast, the Lsm1-7 complex strongly discriminates against cyclic phosphates and tightly binds to oligouridylate tracts with terminal purines. Lsm5 uniquely recognizes purine bases, explaining its divergent sequence relative to other Lsm subunits. Lsm1-7 loads onto RNA from the 3' end and removal of the Lsm1 carboxy-terminal region allows Lsm1-7 to scan along RNA, suggesting a gated mechanism for accessing internal binding sites. These data reveal the molecular basis for RNA binding by Lsm proteins, a fundamental step in the formation of molecular assemblies that are central to eukaryotic mRNA metabolism.
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Affiliation(s)
- Eric J Montemayor
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
- Department of Biomolecular Chemistry, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin 53706, USA
| | - Johanna M Virta
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - Samuel M Hayes
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - Yuichiro Nomura
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - David A Brow
- Department of Biomolecular Chemistry, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin 53706, USA
| | - Samuel E Butcher
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
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7
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Roth AJ, Shuman S, Schwer B. Defining essential elements and genetic interactions of the yeast Lsm2-8 ring and demonstration that essentiality of Lsm2-8 is bypassed via overexpression of U6 snRNA or the U6 snRNP subunit Prp24. RNA (NEW YORK, N.Y.) 2018; 24:853-864. [PMID: 29615482 PMCID: PMC5959253 DOI: 10.1261/rna.066175.118] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/13/2018] [Accepted: 03/30/2018] [Indexed: 06/08/2023]
Abstract
A seven-subunit Lsm2-8 protein ring assembles on the U-rich 3' end of the U6 snRNA. A structure-guided mutational analysis of the Saccharomyces cerevisiae Lsm2-8 ring affords new insights to structure-function relations and genetic interactions of the Lsm subunits. Alanine scanning of 39 amino acids comprising the RNA-binding sites or intersubunit interfaces of Lsm2, Lsm3, Lsm4, Lsm5, and Lsm8 identified only one instance of lethality (Lsm3-R69A) and one severe growth defect (Lsm2-R63A), both involving amino acids that bind the 3'-terminal UUU trinucleotide. All other Ala mutations were benign with respect to vegetative growth. Tests of 235 pairwise combinations of benign Lsm mutants identified six instances of inter-Lsm synthetic lethality and 45 cases of nonlethal synthetic growth defects. Thus, Lsm2-8 ring function is buffered by a network of internal genetic redundancies. A salient finding was that otherwise lethal single-gene deletions lsm2Δ, lsm3Δ, lsm4Δ, lsm5, and lsm8Δ were rescued by overexpression of U6 snRNA from a high-copy plasmid. Moreover, U6 overexpression rescued myriad lsmΔ lsmΔ double-deletions and lsmΔ lsmΔ lsmΔ triple-deletions. We find that U6 overexpression also rescues a lethal deletion of the U6 snRNP protein subunit Prp24 and that Prp24 overexpression bypasses the essentiality of the U6-associated Lsm subunits. Our results indicate that abetting U6 snRNA is the only essential function of the yeast Lsm2-8 proteins.
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Affiliation(s)
- Allen J Roth
- Microbiology and Immunology Department, Weill Cornell Medical College, New York, New York 10065, USA
| | - Stewart Shuman
- Molecular Biology Program, Sloan-Kettering Institute, New York, New York 10065, USA
| | - Beate Schwer
- Microbiology and Immunology Department, Weill Cornell Medical College, New York, New York 10065, USA
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8
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Wason A, Pearce FG, Gerrard JA, Mabbutt BC. Archaeal Lsm rings as stable self-assembling tectons for protein nanofabrication. Biochem Biophys Res Commun 2017; 489:326-331. [PMID: 28559137 DOI: 10.1016/j.bbrc.2017.05.129] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Accepted: 05/23/2017] [Indexed: 10/19/2022]
Abstract
We have exploited the self-assembling properties of archaeal-derived protein Lsmα to generate new supramolecular forms based on its stable ring-shaped heptamer. We show that engineered ring tectons incorporating cysteine sidechains on obverse faces of the Lsmα7 toroid are capable of forming paired and stacked formations. A Cys-modified construct, N10C/E61C-Lsmα, appears to organize into disulfide-mediated tube formations up to 45 nm in length. We additionally report fabrication of cage-like protein clusters through conjugation of Cu2+ to His-tagged variants of the Lsmα7 tecton. These 400 kDa protein capsules are seen as cube particles with visible pores, and are reversibly dissembled into their component ring tectons by EDTA. The β-rich Lsmα supramolecular assemblies described are amenable to further fusion modifications, or for surface attachment, so providing potential for future applications that exploit the RNA-binding capacity of Lsm proteins, such as sensing applications.
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Affiliation(s)
- Akshita Wason
- Biomolecular Interaction Centre and School of Biological Sciences, University of Canterbury, Christchurch 8140, New Zealand
| | - F Grant Pearce
- Biomolecular Interaction Centre and School of Biological Sciences, University of Canterbury, Christchurch 8140, New Zealand
| | - Juliet A Gerrard
- Biomolecular Interaction Centre and School of Biological Sciences, University of Canterbury, Christchurch 8140, New Zealand; MacDiarmid Institute for Advanced Materials and Nanotechnology, Victoria University, Wellington 6140, New Zealand
| | - Bridget C Mabbutt
- Biomolecular Frontiers Research Centre and Department of Chemistry and Biomolecular Sciences, Macquarie University, New South Wales 2109, Australia.
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9
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Agafonov DE, Kastner B, Dybkov O, Hofele RV, Liu WT, Urlaub H, Lührmann R, Stark H. Molecular architecture of the human U4/U6.U5 tri-snRNP. Science 2016; 351:1416-20. [PMID: 26912367 DOI: 10.1126/science.aad2085] [Citation(s) in RCA: 143] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Accepted: 02/04/2016] [Indexed: 12/24/2022]
Abstract
The U4/U6.U5 triple small nuclear ribonucleoprotein (tri-snRNP) is a major spliceosome building block. We obtained a three-dimensional structure of the 1.8-megadalton human tri-snRNP at a resolution of 7 angstroms using single-particle cryo-electron microscopy (cryo-EM). We fit all known high-resolution structures of tri-snRNP components into the EM density map and validated them by protein cross-linking. Our model reveals how the spatial organization of Brr2 RNA helicase prevents premature U4/U6 RNA unwinding in isolated human tri-snRNPs and how the ubiquitin C-terminal hydrolase-like protein Sad1 likely tethers the helicase Brr2 to its preactivation position. Comparison of our model with cryo-EM three-dimensional structures of the Saccharomyces cerevisiae tri-snRNP and Schizosaccharomyces pombe spliceosome indicates that Brr2 undergoes a marked conformational change during spliceosome activation, and that the scaffolding protein Prp8 is also rearranged to accommodate the spliceosome's catalytic RNA network.
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Affiliation(s)
- Dmitry E Agafonov
- Department of Cellular Biochemistry, Max Planck Institute for Biophysical Chemistry, D-37077 Göttingen, Germany
| | - Berthold Kastner
- Department of Cellular Biochemistry, Max Planck Institute for Biophysical Chemistry, D-37077 Göttingen, Germany
| | - Olexandr Dybkov
- Department of Cellular Biochemistry, Max Planck Institute for Biophysical Chemistry, D-37077 Göttingen, Germany
| | - Romina V Hofele
- Bioanalytical Mass Spectrometry, Max Planck Institute for Biophysical Chemistry, D-37077 Göttingen, Germany. Bioanalytics Group, Institute for Clinical Chemistry, University Medical Center Göttingen, D-37075 Göttingen, Germany
| | - Wen-Ti Liu
- Department of 3D Electron Cryomicroscopy, Georg-August Universität Göttingen, D-37077 Göttingen, Germany. Department of Structural Dynamics, Max Planck Institute for Biophysical Chemistry, D-37077 Göttingen, Germany
| | - Henning Urlaub
- Bioanalytical Mass Spectrometry, Max Planck Institute for Biophysical Chemistry, D-37077 Göttingen, Germany. Bioanalytics Group, Institute for Clinical Chemistry, University Medical Center Göttingen, D-37075 Göttingen, Germany.
| | - Reinhard Lührmann
- Department of Cellular Biochemistry, Max Planck Institute for Biophysical Chemistry, D-37077 Göttingen, Germany.
| | - Holger Stark
- Department of 3D Electron Cryomicroscopy, Georg-August Universität Göttingen, D-37077 Göttingen, Germany. Department of Structural Dynamics, Max Planck Institute for Biophysical Chemistry, D-37077 Göttingen, Germany.
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10
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Porebski PJ, Cymborowski M, Pasenkiewicz-Gierula M, Minor W. Fitmunk: improving protein structures by accurate, automatic modeling of side-chain conformations. Acta Crystallogr D Struct Biol 2016; 72:266-80. [PMID: 26894674 PMCID: PMC4756610 DOI: 10.1107/s2059798315024730] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Accepted: 12/23/2015] [Indexed: 11/21/2022] Open
Abstract
Improvements in crystallographic hardware and software have allowed automated structure-solution pipelines to approach a near-`one-click' experience for the initial determination of macromolecular structures. However, in many cases the resulting initial model requires a laborious, iterative process of refinement and validation. A new method has been developed for the automatic modeling of side-chain conformations that takes advantage of rotamer-prediction methods in a crystallographic context. The algorithm, which is based on deterministic dead-end elimination (DEE) theory, uses new dense conformer libraries and a hybrid energy function derived from experimental data and prior information about rotamer frequencies to find the optimal conformation of each side chain. In contrast to existing methods, which incorporate the electron-density term into protein-modeling frameworks, the proposed algorithm is designed to take advantage of the highly discriminatory nature of electron-density maps. This method has been implemented in the program Fitmunk, which uses extensive conformational sampling. This improves the accuracy of the modeling and makes it a versatile tool for crystallographic model building, refinement and validation. Fitmunk was extensively tested on over 115 new structures, as well as a subset of 1100 structures from the PDB. It is demonstrated that the ability of Fitmunk to model more than 95% of side chains accurately is beneficial for improving the quality of crystallographic protein models, especially at medium and low resolutions. Fitmunk can be used for model validation of existing structures and as a tool to assess whether side chains are modeled optimally or could be better fitted into electron density. Fitmunk is available as a web service at http://kniahini.med.virginia.edu/fitmunk/server/ or at http://fitmunk.bitbucket.org/.
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Affiliation(s)
- Przemyslaw Jerzy Porebski
- Department of Molecular Physiology and Biological Physics, University of Virginia, Jordan Hall, 1340 Jefferson Park Avenue, Charlottesville, VA 22908, USA
- Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, ul. Gronostajowa 7, 30-387 Kraków, Poland
| | - Marcin Cymborowski
- Department of Molecular Physiology and Biological Physics, University of Virginia, Jordan Hall, 1340 Jefferson Park Avenue, Charlottesville, VA 22908, USA
| | - Marta Pasenkiewicz-Gierula
- Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, ul. Gronostajowa 7, 30-387 Kraków, Poland
| | - Wladek Minor
- Department of Molecular Physiology and Biological Physics, University of Virginia, Jordan Hall, 1340 Jefferson Park Avenue, Charlottesville, VA 22908, USA
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11
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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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12
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Mura C, Randolph PS, Patterson J, Cozen AE. Archaeal and eukaryotic homologs of Hfq: A structural and evolutionary perspective on Sm function. RNA Biol 2013; 10:636-51. [PMID: 23579284 PMCID: PMC3710371 DOI: 10.4161/rna.24538] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Hfq and other Sm proteins are central in RNA metabolism, forming an evolutionarily conserved family that plays key roles in RNA processing in organisms ranging from archaea to bacteria to human. Sm-based cellular pathways vary in scope from eukaryotic mRNA splicing to bacterial quorum sensing, with at least one step in each of these pathways being mediated by an RNA-associated molecular assembly built upon Sm proteins. Though the first structures of Sm assemblies were from archaeal systems, the functions of Sm-like archaeal proteins (SmAPs) remain murky. Our ignorance about SmAP biology, particularly vis-à-vis the eukaryotic and bacterial Sm homologs, can be partly reduced by leveraging the homology between these lineages to make phylogenetic inferences about Sm functions in archaea. Nevertheless, whether SmAPs are more eukaryotic (RNP scaffold) or bacterial (RNA chaperone) in character remains unclear. Thus, the archaeal domain of life is a missing link, and an opportunity, in Sm-based RNA biology.
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Affiliation(s)
- Cameron Mura
- Department of Chemistry, University of Virginia, Charlottesville, VA, USA
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13
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Abstract
The bacterial Hfq protein is a versatile modulator of RNA function and is particularly important for regulation mediated by small non-coding RNAs. Hfq is a bacterial Sm protein but bears more similarity to the eukaryotic Sm-like (Lsm) family of proteins than the prototypical Sm proteins. Hfq and Lsm proteins share the ability to chaperone RNA-RNA and RNA/protein interactions and an interesting penchant for protecting the 3′ end of a transcript from exonucleolytic decay while encouraging degradation through other pathways. Our view of Lsm function in eukaryotes has historically been informed by studies of Hfq structure and function but mutational analyses and structural studies of Lsm sub-complexes have given important insights as well. Here, we aim to compare and contrast the roles of these evolutionarily related complexes and to highlight areas for future investigation.
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Affiliation(s)
- Carol J Wilusz
- Department of Microbiology, Immunology & Pathology, Colorado State University, Fort Collins, CO, USA.
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14
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Arribas-Layton M, Wu D, Lykke-Andersen J, Song H. Structural and functional control of the eukaryotic mRNA decapping machinery. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2012; 1829:580-9. [PMID: 23287066 DOI: 10.1016/j.bbagrm.2012.12.006] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2012] [Revised: 12/15/2012] [Accepted: 12/17/2012] [Indexed: 01/12/2023]
Abstract
The regulation of mRNA degradation is critical for proper gene expression. Many major pathways for mRNA decay involve the removal of the 5' 7-methyl guanosine (m(7)G) cap in the cytoplasm to allow for 5'-to-3' exonucleolytic decay. The most well studied and conserved eukaryotic decapping enzyme is Dcp2, and its function is aided by co-factors and decapping enhancers. A subset of these factors can act to enhance the catalytic activity of Dcp2, while others might stimulate the remodeling of proteins bound to the mRNA substrate that may otherwise inhibit decapping. Structural studies have provided major insights into the mechanisms by which Dcp2 and decapping co-factors activate decapping. Additional mRNA decay factors can function by recruiting components of the decapping machinery to target mRNAs. mRNA decay factors, decapping factors, and mRNA substrates can be found in cytoplasmic foci named P bodies that are conserved in eukaryotes, though their function remains unknown. In addition to Dcp2, other decapping enzymes have been identified, which may serve to supplement the function of Dcp2 or act in independent decay or quality control pathways. This article is part of a Special Issue entitled: RNA Decay mechanisms.
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