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Chinnam NB, Thapar R, Arvai AS, Sarker AH, Soll JM, Paul T, Syed A, Rosenberg DJ, Hammel M, Bacolla A, Katsonis P, Asthana A, Tsai MS, Ivanov I, Lichtarge O, Silverman RH, Mosammaparast N, Tsutakawa SE, Tainer JA. ASCC1 structures and bioinformatics reveal a novel helix-clasp-helix RNA-binding motif linked to a two-histidine phosphodiesterase. J Biol Chem 2024; 300:107368. [PMID: 38750793 PMCID: PMC11214414 DOI: 10.1016/j.jbc.2024.107368] [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: 01/22/2024] [Revised: 05/07/2024] [Accepted: 05/09/2024] [Indexed: 06/06/2024] Open
Abstract
Activating signal co-integrator complex 1 (ASCC1) acts with ASCC-ALKBH3 complex in alkylation damage responses. ASCC1 uniquely combines two evolutionarily ancient domains: nucleotide-binding K-Homology (KH) (associated with regulating splicing, transcriptional, and translation) and two-histidine phosphodiesterase (PDE; associated with hydrolysis of cyclic nucleotide phosphate bonds). Germline mutations link loss of ASCC1 function to spinal muscular atrophy with congenital bone fractures 2 (SMABF2). Herein analysis of The Cancer Genome Atlas (TCGA) suggests ASCC1 RNA overexpression in certain tumors correlates with poor survival, Signatures 29 and 3 mutations, and genetic instability markers. We determined crystal structures of Alvinella pompejana (Ap) ASCC1 and Human (Hs) PDE domain revealing high-resolution details and features conserved over 500 million years of evolution. Extending our understanding of the KH domain Gly-X-X-Gly sequence motif, we define a novel structural Helix-Clasp-Helix (HCH) nucleotide binding motif and show ASCC1 sequence-specific binding to CGCG-containing RNA. The V-shaped PDE nucleotide binding channel has two His-Φ-Ser/Thr-Φ (HXT) motifs (Φ being hydrophobic) positioned to initiate cyclic phosphate bond hydrolysis. A conserved atypical active-site histidine torsion angle implies a novel PDE substrate. Flexible active site loop and arginine-rich domain linker appear regulatory. Small-angle X-ray scattering (SAXS) revealed aligned KH-PDE RNA binding sites with limited flexibility in solution. Quantitative evolutionary bioinformatic analyses of disease and cancer-associated mutations support implied functional roles for RNA binding, phosphodiesterase activity, and regulation. Collective results inform ASCC1's roles in transactivation and alkylation damage responses, its targeting by structure-based inhibitors, and how ASCC1 mutations may impact inherited disease and cancer.
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Affiliation(s)
- Naga Babu Chinnam
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | - Roopa Thapar
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | - Andrew S Arvai
- Integrative Structural & Computational Biology, The Scripps Research Institute, La Jolla, California, USA
| | - Altaf H Sarker
- Biological Systems and Engineering, Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | - Jennifer M Soll
- Division of Laboratory and Genomic Medicine, Department of Pathology and Immunology, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Tanmoy Paul
- Department of Chemistry, Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, Georgia, USA
| | - Aleem Syed
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | - Daniel J Rosenberg
- Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | - Michal Hammel
- Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | - Albino Bacolla
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | - Panagiotis Katsonis
- Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
| | - Abhishek Asthana
- Department Cancer Biology, Cleveland Clinic Foundation, Lerner Research Institute, Cleveland, Ohio, USA
| | - Miaw-Sheue Tsai
- Biological Systems and Engineering, Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | - Ivaylo Ivanov
- Department of Chemistry, Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, Georgia, USA
| | - Olivier Lichtarge
- Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
| | - Robert H Silverman
- Department Cancer Biology, Cleveland Clinic Foundation, Lerner Research Institute, Cleveland, Ohio, USA
| | - Nima Mosammaparast
- Division of Laboratory and Genomic Medicine, Department of Pathology and Immunology, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Susan E Tsutakawa
- Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, California, USA.
| | - John A Tainer
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA; Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, California, USA; Department of Cancer Biology, University of Texas MD Anderson Cancer Center, Houston, Texas, USA.
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2
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Parajuli P, Craig DB, Gadgeel M, Bagla S, Wright RE, Chu R, Shanti CM, Thirunagari R, Grover SK, Ravindranath Y. Defective monocyte plasticity and altered cAMP pathway characterize USB1-mutated poikiloderma with neutropenia Clericuzio type. Br J Haematol 2024; 204:683-693. [PMID: 37779259 DOI: 10.1111/bjh.19128] [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: 06/13/2023] [Revised: 08/22/2023] [Accepted: 09/15/2023] [Indexed: 10/03/2023]
Abstract
Poikiloderma with neutropenia (PN) Clericuzio type (OMIM #604173) is a rare disease with areas of skin hyper- and hypopigmentation caused by biallelic USB1 variants. The current study was spurred by poor healing of a perianal tear wound in one affected child homozygous for c.266-1G>A (p.E90Sfster8) mutation, from a family reported previously. Treatment with G-CSF/CSF3 or GM-CSF/CSF2 transiently increased neutrophil/monocytes count with no effect on wound healing. Analysis of peripheral blood revealed a lack of non-classical (CD14+/- CD16+ ) monocytes, associated with a systemic inflammatory cytokine profile, in the two affected brothers. Importantly, despite normal expression of cognate receptors, monocytes from PN patients did not respond to M-CSF or IL-34 in vitro, as determined by cytokine secretion or CD16 expression. RNAseq of monocytes showed 293 differentially expressed genes, including significant downregulation of GATA2, AKAP6 and PDE4DIP that are associated with leucocyte differentiation and cyclic adenosine monophosphate (cAMP) signalling. Notably, the plasma cAMP was significantly low in the PN patients. Our study revealed a novel association of PN with a lack of non-classical monocyte population. The defects in monocyte plasticity may contribute to disease manifestations in PN and a defective cAMP signalling may be the primary effect of the splicing errors caused by USB1 mutation.
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Affiliation(s)
- Prahlad Parajuli
- Department of Pharmaceutical and Health Sciences, Eugene Applebaum College of Pharmacy, Wayne State University, Detroit, Michigan, USA
- Barbara Ann Karmanos Cancer Institute, Michigan, Detroit, USA
| | - Douglas B Craig
- Barbara Ann Karmanos Cancer Institute, Michigan, Detroit, USA
- Department of Pediatrics, Wayne State University School of Medicine, Detroit, Michigan, USA
| | - Manisha Gadgeel
- Children's Hospital of Michigan, Detroit Medical Center, Detroit, Michigan, USA
- Central Michigan University, Mt. Pleasant, Michigan, USA
| | - Shruti Bagla
- Department of Pediatrics, Wayne State University School of Medicine, Detroit, Michigan, USA
| | - Robert E Wright
- Department of Pharmaceutical and Health Sciences, Eugene Applebaum College of Pharmacy, Wayne State University, Detroit, Michigan, USA
| | - Roland Chu
- Children's Hospital of Michigan, Detroit Medical Center, Detroit, Michigan, USA
- Central Michigan University, Mt. Pleasant, Michigan, USA
| | - Christina M Shanti
- Children's Hospital of Michigan, Detroit Medical Center, Detroit, Michigan, USA
| | - Rajeev Thirunagari
- Children's Hospital of Michigan, Detroit Medical Center, Detroit, Michigan, USA
| | - Sudershan K Grover
- Children's Hospital of Michigan, Detroit Medical Center, Detroit, Michigan, USA
| | - Yaddanapudi Ravindranath
- Barbara Ann Karmanos Cancer Institute, Michigan, Detroit, USA
- Department of Pediatrics, Wayne State University School of Medicine, Detroit, Michigan, USA
- Children's Hospital of Michigan, Detroit Medical Center, Detroit, Michigan, USA
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3
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Huynh TN, Parker R. The PARN, TOE1, and USB1 RNA deadenylases and their roles in non-coding RNA regulation. J Biol Chem 2023; 299:105139. [PMID: 37544646 PMCID: PMC10493513 DOI: 10.1016/j.jbc.2023.105139] [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: 05/13/2023] [Revised: 07/28/2023] [Accepted: 07/29/2023] [Indexed: 08/08/2023] Open
Abstract
The levels of non-coding RNAs (ncRNAs) are regulated by transcription, RNA processing, and RNA degradation pathways. One mechanism for the degradation of ncRNAs involves the addition of oligo(A) tails by non-canonical poly(A) polymerases, which then recruit processive sequence-independent 3' to 5' exonucleases for RNA degradation. This pathway of decay is also regulated by three 3' to 5' exoribonucleases, USB1, PARN, and TOE1, which remove oligo(A) tails and thereby can protect ncRNAs from decay in a manner analogous to the deubiquitination of proteins. Loss-of-function mutations in these genes lead to premature degradation of some ncRNAs and lead to specific human diseases such as Poikiloderma with Neutropenia (PN) for USB1, Dyskeratosis Congenita (DC) for PARN and Pontocerebellar Hypoplasia type 7 (PCH7) for TOE1. Herein, we review the biochemical properties of USB1, PARN, and TOE1, how they modulate ncRNA levels, and their roles in human diseases.
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Affiliation(s)
- Thao Ngoc Huynh
- Department of Biochemistry, University of Colorado Boulder, Boulder, Colorado, USA
| | - Roy Parker
- Department of Biochemistry, University of Colorado Boulder, Boulder, Colorado, USA; Howard Hughes Medical Institute, Chevy Chase, Maryland, USA.
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Zhou S, Van Bortle K. The Pol III transcriptome: Basic features, recurrent patterns, and emerging roles in cancer. WILEY INTERDISCIPLINARY REVIEWS. RNA 2023; 14:e1782. [PMID: 36754845 PMCID: PMC10498592 DOI: 10.1002/wrna.1782] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2022] [Revised: 01/13/2023] [Accepted: 01/18/2023] [Indexed: 02/10/2023]
Abstract
The RNA polymerase III (Pol III) transcriptome is universally comprised of short, highly structured noncoding RNA (ncRNA). Through RNA-protein interactions, the Pol III transcriptome actuates functional activities ranging from nuclear gene regulation (7SK), splicing (U6, U6atac), and RNA maturation and stability (RMRP, RPPH1, Y RNA), to cytoplasmic protein targeting (7SL) and translation (tRNA, 5S rRNA). In higher eukaryotes, the Pol III transcriptome has expanded to include additional, recently evolved ncRNA species that effectively broaden the footprint of Pol III transcription to additional cellular activities. Newly evolved ncRNAs function as riboregulators of autophagy (vault), immune signaling cascades (nc886), and translation (Alu, BC200, snaR). Notably, upregulation of Pol III transcription is frequently observed in cancer, and multiple ncRNA species are linked to both cancer progression and poor survival outcomes among cancer patients. In this review, we outline the basic features and functions of the Pol III transcriptome, and the evidence for dysregulation and dysfunction for each ncRNA in cancer. When taken together, recurrent patterns emerge, ranging from shared functional motifs that include molecular scaffolding and protein sequestration, overlapping protein interactions, and immunostimulatory activities, to the biogenesis of analogous small RNA fragments and noncanonical miRNAs, augmenting the function of the Pol III transcriptome and further broadening its role in cancer. This article is categorized under: RNA in Disease and Development > RNA in Disease RNA Processing > Processing of Small RNAs RNA Interactions with Proteins and Other Molecules > Protein-RNA Interactions: Functional Implications.
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Affiliation(s)
- Sihang Zhou
- Department of Cell and Developmental Biology, University of Illinois Urbana-Champaign, Urbana, Illinois, USA
| | - Kevin Van Bortle
- Department of Cell and Developmental Biology, University of Illinois Urbana-Champaign, Urbana, Illinois, USA
- Cancer Center at Illinois, University of Illinois Urbana-Champaign, Urbana, Illinois, USA
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5
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Goguen EC, Brow DA. Domains and residues of the Saccharomyces cerevisiae hnRNP protein Hrp1 important for transcriptional autoregulation and noncoding RNA termination. Genetics 2023; 225:iyad134. [PMID: 37467478 PMCID: PMC10471224 DOI: 10.1093/genetics/iyad134] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Revised: 07/05/2023] [Accepted: 07/12/2023] [Indexed: 07/21/2023] Open
Abstract
Proteins that bind the nascent transcript exiting RNA polymerase II can regulate transcription elongation. The essential Saccharomyces cerevisiae hnRNP protein Hrp1 is one such protein and participates in both cleavage and polyadenylation-coupled and Nrd1-Nab3-Sen1-dependent RNA polymerase II termination. Prior evidence that Hrp1 is a positive RNA polymerase II elongation factor suggests that its release from the elongation complex promotes termination. Here we report the effects of deletions and substitutions in Hrp1 on its autoregulation via an Nrd1-Nab3-Sen1-dependent transcription attenuator in the 5'-UTR of its mRNA and on the function of an Hrp1-dependent Nrd1-Nab3-Sen1 terminator in the SNR82 snoRNA gene. Deletion of either of two central RNA recognition motifs or either of the flanking low-sequence complexity domains is lethal. Smaller, viable deletions in the amino-terminal low-sequence complexity domain cause readthrough of both the HRP1 attenuator and SNR82 terminator. Substitutions that cause readthrough localized mostly to the RNA recognition motifs, although not always to the RNA-binding face. We found that autoregulation of Hrp1 mRNA synthesis is surprisingly robust, overcoming the expected lethal effects of the start codon and frameshift mutations via overexpression of the mRNA up to 40-fold. Our results suggest a model in which binding of attenuator or terminator elements in the nascent transcript by RNA recognition motifs 1 and 2 disrupts interactions between RNA recognition motif 2 and the RNA polymerase II elongation complex, increasing its susceptibility to termination.
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Affiliation(s)
- Emma C Goguen
- Department of Biomolecular Chemistry, University of Wisconsin School of Medicine and Public Health, Madison, WI 53706, USA
| | - David A Brow
- Department of Biomolecular Chemistry, University of Wisconsin School of Medicine and Public Health, Madison, WI 53706, USA
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Jeong HC, Shukla S, Fok WC, Huynh TN, Batista LFZ, Parker R. USB1 is a miRNA deadenylase that regulates hematopoietic development. Science 2023; 379:901-907. [PMID: 36862787 PMCID: PMC10827040 DOI: 10.1126/science.abj8379] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Accepted: 02/03/2023] [Indexed: 03/04/2023]
Abstract
Mutations in the 3' to 5' RNA exonuclease USB1 cause hematopoietic failure in poikiloderma with neutropenia (PN). Although USB1 is known to regulate U6 small nuclear RNA maturation, the molecular mechanism underlying PN remains undetermined, as pre-mRNA splicing is unaffected in patients. We generated human embryonic stem cells harboring the PN-associated mutation c.531_delA in USB1 and show that this mutation impairs human hematopoiesis. Dysregulated microRNA (miRNA) levels in USB1 mutants during blood development contribute to hematopoietic failure, because of a failure to remove 3'-end adenylated tails added by PAPD5/7. Modulation of miRNA 3'-end adenylation through genetic or chemical inhibition of PAPD5/7 rescues hematopoiesis in USB1 mutants. This work shows that USB1 acts as a miRNA deadenylase and suggests PAPD5/7 inhibition as a potential therapy for PN.
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Affiliation(s)
- Ho-Chang Jeong
- Division of Hematology, Department of Medicine, Washington University in St. Louis, St. Louis, MO 63110, USA
- Center for Genome Integrity, Siteman Cancer Center, Washington University in St. Louis, St. Louis, MO 63110, USA
| | - Siddharth Shukla
- Department of Biochemistry, University of Colorado, Boulder, CO 80303, USA
- Howard Hughes Medical Institute, Chevy Chase MD 20815, USA
| | - Wilson Chun Fok
- Division of Hematology, Department of Medicine, Washington University in St. Louis, St. Louis, MO 63110, USA
- Center for Genome Integrity, Siteman Cancer Center, Washington University in St. Louis, St. Louis, MO 63110, USA
| | - Thao Ngoc Huynh
- Department of Biochemistry, University of Colorado, Boulder, CO 80303, USA
- Howard Hughes Medical Institute, Chevy Chase MD 20815, USA
| | - Luis Francisco Zirnberger Batista
- Division of Hematology, Department of Medicine, Washington University in St. Louis, St. Louis, MO 63110, USA
- Center for Genome Integrity, Siteman Cancer Center, Washington University in St. Louis, St. Louis, MO 63110, USA
| | - Roy Parker
- Department of Biochemistry, University of Colorado, Boulder, CO 80303, USA
- Howard Hughes Medical Institute, Chevy Chase MD 20815, USA
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Specificity and Mechanism of Coronavirus, Rotavirus, and Mammalian Two-Histidine Phosphoesterases That Antagonize Antiviral Innate Immunity. mBio 2021; 12:e0178121. [PMID: 34372695 PMCID: PMC8406329 DOI: 10.1128/mbio.01781-21] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
The 2′,5′-oligoadenylate (2-5A)-dependent endoribonuclease, RNase L, is a principal mediator of the interferon (IFN) antiviral response. Therefore, the regulation of cellular levels of 2-5A is a key point of control in antiviral innate immunity. Cellular 2-5A levels are determined by IFN-inducible 2′,5′-oligoadenylate synthetases (OASs) and by enzymes that degrade 2-5A. Importantly, many coronaviruses (CoVs) and rotaviruses encode 2-5A-degrading enzymes, thereby antagonizing RNase L and its antiviral effects. A-kinase-anchoring protein 7 (AKAP7), a mammalian counterpart, could possibly limit tissue damage from excessive or prolonged RNase L activation during viral infections or from self-double-stranded RNAs that activate OAS. We show that these enzymes, members of the two-histidine phosphoesterase (2H-PE) superfamily, constitute a subfamily referred here as 2′,5′-PEs. 2′,5′-PEs from the mouse CoV mouse hepatitis virus (MHV) (NS2), Middle East respiratory syndrome coronavirus (MERS-CoV) (NS4b), group A rotavirus (VP3), and mouse (AKAP7) were investigated for their evolutionary relationships and activities. While there was no activity against 3′,5′-oligoribonucleotides, they all cleaved 2′,5′-oligoadenylates efficiently but with variable activity against other 2′,5′-oligonucleotides. The 2′,5′-PEs are shown to be metal ion-independent enzymes that cleave trimer 2-5A (2′,5′-p3A3) producing mono- or diadenylates with 2′,3′-cyclic phosphate termini. Our results suggest that the elimination of 2-5A might be the sole function of viral 2′,5′-PEs, thereby promoting viral escape from innate immunity by preventing or limiting the activation of RNase L.
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Abstract
QM/MM simulations have become an indispensable tool in many chemical and biochemical investigations. Considering the tremendous degree of success, including recognition by a 2013 Nobel Prize in Chemistry, are there still "burning challenges" in QM/MM methods, especially for biomolecular systems? In this short Perspective, we discuss several issues that we believe greatly impact the robustness and quantitative applicability of QM/MM simulations to many, if not all, biomolecules. We highlight these issues with observations and relevant advances from recent studies in our group and others in the field. Despite such limited scope, we hope the discussions are of general interest and will stimulate additional developments that help push the field forward in meaningful directions.
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Affiliation(s)
- Qiang Cui
- Departments of Chemistry, Physics, and Biomedical Engineering, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, United States
| | - Tanmoy Pal
- Department of Chemistry, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, United States
| | - Luke Xie
- Department of Chemistry, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, United States
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9
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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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10
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Roithová A, Feketová Z, Vaňáčová Š, Staněk D. DIS3L2 and LSm proteins are involved in the surveillance of Sm ring-deficient snRNAs. Nucleic Acids Res 2020; 48:6184-6197. [PMID: 32374871 PMCID: PMC7293007 DOI: 10.1093/nar/gkaa301] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Revised: 04/06/2020] [Accepted: 04/23/2020] [Indexed: 01/31/2023] Open
Abstract
Spliceosomal small nuclear ribonucleoprotein particles (snRNPs) undergo a complex maturation pathway containing multiple steps in the nucleus and in the cytoplasm. snRNP biogenesis is strictly proofread and several quality control checkpoints are placed along the pathway. Here, we analyzed the fate of small nuclear RNAs (snRNAs) that are unable to acquire a ring of Sm proteins. We showed that snRNAs lacking the Sm ring are unstable and accumulate in P-bodies in an LSm1-dependent manner. We further provide evidence that defective snRNAs without the Sm binding site are uridylated at the 3′ end and associate with DIS3L2 3′→5′ exoribonuclease and LSm proteins. Finally, inhibition of 5′→3′ exoribonuclease XRN1 increases association of ΔSm snRNAs with DIS3L2, which indicates competition and compensation between these two degradation enzymes. Together, we provide evidence that defective snRNAs without the Sm ring are uridylated and degraded by alternative pathways involving either DIS3L2 or LSm proteins and XRN1.
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Affiliation(s)
- Adriana Roithová
- Laboratory of RNA Biology, Institute of Molecular Genetics of the Czech Academy of Sciences, Videnska 1083, 14220 Prague, Czech Republic.,Faculty of Science, Charles University, 128 00 Prague, Czech Republic
| | - Zuzana Feketová
- CEITEC-Central European Institute of Technology, Masaryk University, Kamenice 5/A35, 625 00 Brno, Czech Republic
| | - Štěpánka Vaňáčová
- CEITEC-Central European Institute of Technology, Masaryk University, Kamenice 5/A35, 625 00 Brno, Czech Republic
| | - David Staněk
- Laboratory of RNA Biology, Institute of Molecular Genetics of the Czech Academy of Sciences, Videnska 1083, 14220 Prague, Czech Republic
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11
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Nomura Y, Montemayor EJ, Virta JM, Hayes SM, Butcher SE. Structural basis for the evolution of cyclic phosphodiesterase activity in the U6 snRNA exoribonuclease Usb1. Nucleic Acids Res 2020; 48:1423-1434. [PMID: 31832688 PMCID: PMC7026655 DOI: 10.1093/nar/gkz1177] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Revised: 12/02/2019] [Accepted: 12/05/2019] [Indexed: 11/28/2022] Open
Abstract
U6 snRNA undergoes post-transcriptional 3′ end modification prior to incorporation into the active site of spliceosomes. The responsible exoribonuclease is Usb1, which removes nucleotides from the 3′ end of U6 and, in humans, leaves a 2′,3′ cyclic phosphate that is recognized by the Lsm2–8 complex. Saccharomycescerevisiae Usb1 has additional 2′,3′ cyclic phosphodiesterase (CPDase) activity, which converts the cyclic phosphate into a 3′ phosphate group. Here we investigate the molecular basis for the evolution of Usb1 CPDase activity. We examine the structure and function of Usb1 from Kluyveromyces marxianus, which shares 25 and 19% sequence identity to the S. cerevisiae and Homo sapiens orthologs of Usb1, respectively. We show that K. marxianus Usb1 enzyme has CPDase activity and determined its structure, free and bound to the substrate analog uridine 5′-monophosphate. We find that the origin of CPDase activity is related to a loop structure that is conserved in yeast and forms a distinct penultimate (n – 1) nucleotide binding site. These data provide structural and mechanistic insight into the evolutionary divergence of Usb1 catalysis.
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Affiliation(s)
- Yuichiro Nomura
- Department of Biochemistry, University of Wisconsin, Madison, WI 53706, USA
| | - Eric J Montemayor
- Department of Biochemistry, University of Wisconsin, Madison, WI 53706, USA
| | - Johanna M Virta
- Department of Biochemistry, University of Wisconsin, Madison, WI 53706, USA
| | - Samuel M Hayes
- Department of Biochemistry, University of Wisconsin, Madison, WI 53706, USA
| | - Samuel E Butcher
- Department of Biochemistry, University of Wisconsin, Madison, WI 53706, USA
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12
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Roston D, Demapan D, Cui Q. Extensive free-energy simulations identify water as the base in nucleotide addition by DNA polymerase. Proc Natl Acad Sci U S A 2019; 116:25048-25056. [PMID: 31757846 PMCID: PMC6911213 DOI: 10.1073/pnas.1914613116] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Transphosphorylation of nucleotide triphosphates is the central reaction in DNA replication by DNA polymerase as well as many other biological processes. Despite its importance, the microscopic chemical mechanism of transphosphorylation of nucleotide triphosphates is, in most cases, unknown. Here we use extensive simulations of DNA polymerase η to test mechanistic hypotheses. We systematically survey the reactive space by calculating 2D free-energy surfaces for 10 different plausible mechanisms that have been proposed. We supplement these free-energy surfaces with calculations of pKa for a number of potentially acidic protons in different states relevant to the catalytic cycle. We find that among all of the conditions that we test, the smallest activation barrier occurs for a reaction where a Mg2+-coordinated water deprotonates the nucleophilic 3'-OH, and this deprotonation is concerted with the phosphoryl transfer. The presence of a third Mg2+ in the active site lowers the activation barrier for the water-as-base mechanism, as does protonation of the pyrophosphate leaving group, which is consistent with general acid catalysis. The results demonstrate the value of simulations, when used in conjunction with experimental data, to help establish a microscopic chemical mechanism in a complex environment.
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Affiliation(s)
- Daniel Roston
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, CA 92093;
| | - Darren Demapan
- Department of Chemistry, Boston University, Boston, MA 02215
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI 53706
| | - Qiang Cui
- Department of Chemistry, Boston University, Boston, MA 02215;
- Department of Physics, Boston University, Boston, MA 02215
- Department of Biomedical Engineering, Boston University, Boston, MA 02215
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Antagonism of dsRNA-Induced Innate Immune Pathways by NS4a and NS4b Accessory Proteins during MERS Coronavirus Infection. mBio 2019; 10:mBio.00319-19. [PMID: 30914508 PMCID: PMC6437052 DOI: 10.1128/mbio.00319-19] [Citation(s) in RCA: 82] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Middle East respiratory syndrome coronavirus (MERS-CoV) is the second novel zoonotic
coronavirus to emerge in the 21st century and cause outbreaks of severe respiratory
disease. More than 2,200 cases and 800 deaths have been reported to date, yet there are no
licensed vaccines or treatments. Coronaviruses encode unique accessory proteins that are
not required for replication but most likely play roles in immune antagonism and/or
pathogenesis. Our study describes the functions of MERS-CoV accessory proteins NS4a and
NS4b during infection of a human airway-derived cell line. Loss of these accessory
proteins during MERS-CoV infection leads to host antiviral activation and modestly
attenuates replication. In the case of both NS4a and NS4b, we have identified roles during
infection not previously described, yet the lack of robust activation suggests much
remains to be learned about the interactions between MERS-CoV and the infected host. Middle East respiratory syndrome coronavirus (MERS-CoV) was first identified in 2012 as a
novel etiological agent of severe respiratory disease in humans. As during infection by
other viruses, host sensing of viral double-stranded RNA (dsRNA) induces several antiviral
pathways. These include interferon (IFN), oligoadenylate synthetase (OAS)-RNase L, and
protein kinase R (PKR). Coronaviruses, including MERS-CoV, potently suppress the
activation of these pathways, inducing only modest host responses. Our study describes the
functions of two accessory proteins unique to MERS-CoV and related viruses, NS4a and NS4b,
during infection in human airway epithelium-derived A549 cells. NS4a has been previously
characterized as a dsRNA binding protein, while NS4b is a
2′,5′-phosphodiesterase with structural and enzymatic similarity to NS2
encoded by mouse hepatitis virus (MHV). We found that deletion of NS4a results in
increased interferon lambda (IFNL1) expression, as does mutation of
either the catalytic site or nuclear localization sequence of NS4b. All of the mutant
viruses we tested exhibited slight decreases in replication. We previously reported that,
like MHV NS2, NS4b antagonizes OAS-RNase L, but suppression of IFN is a previously
unidentified function for viral phosphodiesterases. Unexpectedly, deletion of NS4a does
not result in robust activation of the PKR or OAS-RNase L pathways. Therefore, MERS-CoV
likely encodes other proteins that contribute to suppression or evasion of these antiviral
innate immune pathways that should be an important focus of future work. This study
provides additional insight into the complex interactions between MERS-CoV and the host
immune response.
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14
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Abiotic phosphorus recycling from adsorbed ribonucleotides on a ferrihydrite-type mineral: Probing solution and surface species. J Colloid Interface Sci 2019; 547:171-182. [PMID: 30954001 DOI: 10.1016/j.jcis.2019.03.086] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2019] [Revised: 03/23/2019] [Accepted: 03/25/2019] [Indexed: 01/21/2023]
Abstract
Iron (Fe) (oxyhydr)oxide minerals, which are amongst most reactive minerals in soils and sediments, are known to exhibit strong adsorption of inorganic phosphate (Pi) and organophosphate (Po) compounds. Beyond synthetic Po compounds, much still remains unknown about the reactivity of these minerals to transform naturally-occurring Po compounds to Pi, particularly with respect to solution versus surface speciation of Po hydrolysis. To investigate this reactivity with a ferrihydrite-type mineral and ribonucleotides, we employed high-resolution liquid chromatography-mass spectrometry (LC-MS), X-ray absorption near-edge structure (XANES), Fourier-transform infrared (FTIR) spectroscopy, and molecular modeling. Kinetic experiments were conducted with the mineral (1 g L-1) reacted with adenosine monophosphate, diphosphate, or triphosphate (respectively AMP, ADP, ATP; 50 µM). Analysis of solution organic species by LC-MS implied that only adsorption occurred with AMP and ADP but both adsorption and dephosphorylation of ATP were evident. Maximum adsorption capacities per gram of mineral were 40.6 ± 0.8 µmol AMP, 35.7 ± 1.6 µmol ADP, and 10.9 ± 1.0 µmol ATP; solution dephosphorylated by-products accounted for 15% of initial ATP. Subsequent XANES analysis of the surface species revealed that 16% of adsorbed AMP and 30% of adsorbed ATP were subjected to dephosphorylation, which was not fully quantifiable from the solution measurements. Molecular simulations predicted that ADP and ATP were complexed mainly via the phosphate groups whereas AMP binding also involved multiple hydrogen bonds with the adenosine moiety; our FTIR data confirmed these binding confirmations. Our findings thus imply that specific adsorption mechanisms dictate the recycling and subsequent trapping of Pi from ribonucleotide-like biomolecules reacted with Fe (oxyhydr)oxide minerals.
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