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Husain RA, Jiao X, Hennings JC, Giesecke J, Palsule G, Beck-Wödl S, Osmanović D, Bjørgo K, Mir A, Ilyas M, Abbasi SM, Efthymiou S, Dominik N, Maroofian R, Houlden H, Rankin J, Pagnamenta AT, Nashabat M, Altwaijri W, Alfadhel M, Umair M, Khouj E, Reardon W, El-Hattab AW, Mekki M, Houge G, Beetz C, Bauer P, Putoux A, Lesca G, Sanlaville D, Alkuraya FS, Taylor RW, Mentzel HJ, Hübner CA, Huppke P, Hart RP, Haack TB, Kiledjian M, Rubio I. Biallelic NUDT2 variants defective in mRNA decapping cause a neurodevelopmental disease. Brain 2024; 147:1197-1205. [PMID: 38141063 PMCID: PMC10994549 DOI: 10.1093/brain/awad434] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Revised: 11/08/2023] [Accepted: 12/05/2023] [Indexed: 12/24/2023] Open
Abstract
Dysfunctional RNA processing caused by genetic defects in RNA processing enzymes has a profound impact on the nervous system, resulting in neurodevelopmental conditions. We characterized a recessive neurological disorder in 18 children and young adults from 10 independent families typified by intellectual disability, motor developmental delay and gait disturbance. In some patients peripheral neuropathy, corpus callosum abnormalities and progressive basal ganglia deposits were present. The disorder is associated with rare variants in NUDT2, a mRNA decapping and Ap4A hydrolysing enzyme, including novel missense and in-frame deletion variants. We show that these NUDT2 variants lead to a marked loss of enzymatic activity, strongly implicating loss of NUDT2 function as the cause of the disorder. NUDT2-deficient patient fibroblasts exhibit a markedly altered transcriptome, accompanied by changes in mRNA half-life and stability. Amongst the most up-regulated mRNAs in NUDT2-deficient cells, we identified host response and interferon-responsive genes. Importantly, add-back experiments using an Ap4A hydrolase defective in mRNA decapping highlighted loss of NUDT2 decapping as the activity implicated in altered mRNA homeostasis. Our results confirm that reduction or loss of NUDT2 hydrolase activity is associated with a neurological disease, highlighting the importance of a physiologically balanced mRNA processing machinery for neuronal development and homeostasis.
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Affiliation(s)
- Ralf A Husain
- Department of Neuropediatrics, Jena University Hospital, 07747 Jena, Germany
- Center for Rare Diseases, Jena University Hospital, 07747 Jena, Germany
| | - Xinfu Jiao
- Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, NJ 08854, USA
| | | | - Jan Giesecke
- Department of Anaesthesiology and Intensive Care Medicine, Jena University Hospital, Member of the Leibniz Center for Photonics in Infection Research (LPI), 07747 Jena, Germany
| | - Geeta Palsule
- Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, NJ 08854, USA
| | - Stefanie Beck-Wödl
- Institute of Medical Genetics and Applied Genomics, University of Tübingen, 72076 Tübingen, Germany
| | - Dina Osmanović
- Institute of Human Genetics, Jena University Hospital, 07747 Jena, Germany
| | - Kathrine Bjørgo
- Department of Medical Genetics, Oslo University Hospital, 0424 Oslo, Norway
| | - Asif Mir
- Department of Biological Sciences, Faculty of Sciences, International Islamic University, Islamabad 44000, Pakistan
| | - Muhammad Ilyas
- Department of Biological Sciences, Faculty of Sciences, International Islamic University, Islamabad 44000, Pakistan
| | - Saad M Abbasi
- Department of Biological Sciences, Faculty of Sciences, International Islamic University, Islamabad 44000, Pakistan
| | - Stephanie Efthymiou
- Department of Neuromuscular Disorders, UCL Queen Square Institute of Neurology, London, WC1N 3BG, UK
| | - Natalia Dominik
- Department of Neuromuscular Disorders, UCL Queen Square Institute of Neurology, London, WC1N 3BG, UK
| | - Reza Maroofian
- Department of Neuromuscular Disorders, UCL Queen Square Institute of Neurology, London, WC1N 3BG, UK
| | - Henry Houlden
- Department of Neuromuscular Disorders, UCL Queen Square Institute of Neurology, London, WC1N 3BG, UK
| | - Julia Rankin
- Department of Clinical Genetics, Royal Devon University Hospital, Exeter, EX1 2ED, UK
| | - Alistair T Pagnamenta
- Oxford NIHR Biomedical Research Centre, Wellcome Centre for Human Genetics, Oxford, OX3 7BN, UK
| | - Marwan Nashabat
- Medical Genomics Research Department, King Abdullah International Medical Research Center, Ministry of National Guard Health Affairs, Riyadh 11426, Saudi Arabia
| | - Waleed Altwaijri
- Department of Pediatrics, Neurology Division, King Abdullah Specialist Children’s Hospital, King Abdulaziz Medical City, Ministry of National Guard Health Affairs, Riyadh 11426, Saudi Arabia
| | - Majid Alfadhel
- Medical Genomics Research Department, King Abdullah International Medical Research Center, Ministry of National Guard Health Affairs, Riyadh 11426, Saudi Arabia
- King Saud Bin Abdulaziz University for Health Sciences, Ministry of National Guard Health Affairs, Riyadh 11426, Saudi Arabia
- Genetics and Precision Medicine Department, King Abdullah Specialized Children's Hospital, King Abdulaziz Medical City, Ministry of National Guard Health Affairs, Riyadh 11426, Saudi Arabia
| | - Muhammad Umair
- Medical Genomics Research Department, King Abdullah International Medical Research Center, Ministry of National Guard Health Affairs, Riyadh 11426, Saudi Arabia
- King Saud Bin Abdulaziz University for Health Sciences, Ministry of National Guard Health Affairs, Riyadh 11426, Saudi Arabia
| | - Ebtissal Khouj
- Department of Translational Genomics, Centre for Genomic Medicine, King Faisal Specialist Hospital and Research Centre, Riyadh 11211, Saudi Arabia
| | | | - Ayman W El-Hattab
- Department of Clinical Sciences, College of Medicine, University of Sharjah, 27272, Sharjah, United Arab Emirates
- Department of Pediatrics, University Hospital Sharjah, 72772, Sharjah, United Arab Emirates
| | - Mohammed Mekki
- Department of Pediatrics, University Hospital Sharjah, 72772, Sharjah, United Arab Emirates
| | - Gunnar Houge
- Department of Medical Genetics, Haukeland University Hospital, 5021 Bergen, Norway
| | | | | | - Audrey Putoux
- Groupement Hospitalier Est, Hospices Civils de Lyon, Service de Génétique, Centre de Référence Anomalies du Développement, 69677 Bron Cedex, France
- Équipe GENDEV, Centre de Recherche en Neurosciences de Lyon, Univ Lyon, Univ Lyon 1, INSERM U1028 CNRS UMR5292, 69008 Lyon, France
| | - Gaetan Lesca
- Groupement Hospitalier Est, Hospices Civils de Lyon, Service de Génétique, Centre de Référence Anomalies du Développement, 69677 Bron Cedex, France
- Physiopathologie et Génétique du Neurone et du Muscle, Univ Lyon, Univ Lyon 1, CNRS, INSERM, UMR5261, U1315, Institut NeuroMyoGène, 69008 Lyon, France
| | - Damien Sanlaville
- Groupement Hospitalier Est, Hospices Civils de Lyon, Service de Génétique, Centre de Référence Anomalies du Développement, 69677 Bron Cedex, France
- Physiopathologie et Génétique du Neurone et du Muscle, Univ Lyon, Univ Lyon 1, CNRS, INSERM, UMR5261, U1315, Institut NeuroMyoGène, 69008 Lyon, France
| | - Fowzan S Alkuraya
- Department of Translational Genomics, Centre for Genomic Medicine, King Faisal Specialist Hospital and Research Centre, Riyadh 11211, Saudi Arabia
| | - Robert W Taylor
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
- NHS Highly Specialised Service for Rare Mitochondrial Disorders, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, NE1 4LP, UK
| | - Hans-Joachim Mentzel
- Center for Rare Diseases, Jena University Hospital, 07747 Jena, Germany
- Section of Pediatric Radiology, Department of Radiology, Jena University Hospital, 07747 Jena, Germany
| | - Christian A Hübner
- Center for Rare Diseases, Jena University Hospital, 07747 Jena, Germany
- Institute of Human Genetics, Jena University Hospital, 07747 Jena, Germany
| | - Peter Huppke
- Department of Neuropediatrics, Jena University Hospital, 07747 Jena, Germany
- Center for Rare Diseases, Jena University Hospital, 07747 Jena, Germany
| | - Ronald P Hart
- Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, NJ 08854, USA
| | - Tobias B Haack
- Institute of Medical Genetics and Applied Genomics, University of Tübingen, 72076 Tübingen, Germany
| | - Megerditch Kiledjian
- Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, NJ 08854, USA
| | - Ignacio Rubio
- Department of Anaesthesiology and Intensive Care Medicine, Jena University Hospital, Member of the Leibniz Center for Photonics in Infection Research (LPI), 07747 Jena, Germany
- Center for Sepsis Control and Care, Jena University Hospital, 07747 Jena, Germany
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2
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Rack JGM, Ahel I. A Simple Method to Study ADP-Ribosylation Reversal: From Function to Drug Discovery. Methods Mol Biol 2023; 2609:111-132. [PMID: 36515833 DOI: 10.1007/978-1-0716-2891-1_8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
ADP-ribosylation is an ancient modification of proteins, nucleic acids, and other biomolecules found in all kingdoms of life as well as in certain viruses. The regulation of fundamental (patho)physiological processes by ADP-ribosylation, including the cellular stress response, inflammation, and immune response to bacterial and viral pathogens, has created a strong interest into the study of modification establishment and removal to explore novel therapeutic approaches. Beyond ADP-ribosylation in humans, direct targeting of factors that alter host ADP-ribosylation signaling (e.g., viral macrodomains) or utilize ADP-ribosylation to manipulate host cell behavior (e.g., bacterial toxins) were shown to reduce virulence and disease severity. However, the realization of these therapeutic potentials is thus far hampered by the unavailability of simple, high-throughput methods to study the modification "writers" and "erasers" and screen for novel inhibitors.Here, we describe a scalable method for the measurement of (ADP-ribosyl)hydrolase activity. The assay relies on the conversion of ADP-ribose released from a modified substrate by the (ADP-ribosyl)hydrolase under investigation into AMP by the phosphodiesterase NudT5 into bioluminescence via a commercially available detection assay. Moreover, this method can be utilized to study the role of nudix- or ENPP-type phosphodiesterases in ADP-ribosylation processing and may also be adapted to investigate the activity of (ADP-ribosyl)transferases. Overall, this method is applicable for both basic biochemical characterization and screening of large drug libraries; hence, it is highly adaptable to diverse project needs.
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Affiliation(s)
| | - Ivan Ahel
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK
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Drabinska J, Steczkiewicz K, Kujawa M, Kraszewska E. Searching for Biological Function of the Mysterious PA2504 Protein from Pseudomonas aeruginosa. Int J Mol Sci 2021; 22:ijms22189833. [PMID: 34575996 PMCID: PMC8466066 DOI: 10.3390/ijms22189833] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Revised: 09/08/2021] [Accepted: 09/09/2021] [Indexed: 11/16/2022] Open
Abstract
For nearly half of the proteome of an important pathogen, Pseudomonas aeruginosa, the function has not yet been recognised. Here, we characterise one such mysterious protein PA2504, originally isolated by us as a sole partner of the RppH RNA hydrolase involved in transcription regulation of multiple genes. This study aims at elucidating details of PA2504 function and discussing its implications for bacterial biology. We show that PA2504 forms homodimers and is evenly distributed in the cytoplasm of bacterial cells. Molecular modelling identified the presence of a Tudor-like domain in PA2504. Transcriptomic analysis of a ΔPA2504 mutant showed that 42 transcripts, mainly coding for proteins involved in sulphur metabolism, were affected by the lack of PA2504. In vivo crosslinking of cellular proteins in the exponential and stationary phase of growth revealed several polypeptides that bound to PA2504 exclusively in the stationary phase. Mass spectrometry analysis identified them as the 30S ribosomal protein S4, the translation elongation factor TufA, and the global response regulator GacA. These results indicate that PA2504 may function as a tether for several important cellular factors.
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Zong G, Jork N, Hostachy S, Fiedler D, Jessen HJ, Shears SB, Wang H. New structural insights reveal an expanded reaction cycle for inositol pyrophosphate hydrolysis by human DIPP1. FASEB J 2021; 35:e21275. [PMID: 33475202 DOI: 10.1096/fj.202001489r] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Revised: 10/30/2020] [Accepted: 11/30/2020] [Indexed: 11/11/2022]
Abstract
Nudix hydrolases attract considerable attention for their wide range of specialized activities in all domains of life. One particular group of Nudix phosphohydrolases (DIPPs), through their metabolism of diphosphoinositol polyphosphates (PP-InsPs), regulates the actions of these polyphosphates upon bioenergetic homeostasis. In the current study, we describe, at an atomic level, hitherto unknown properties of human DIPP1.We provide X-ray analysis of the catalytic core of DIPP1 in crystals complexed with either natural PP-InsPs, alternative PP-InsP stereoisomers, or non-hydrolysable methylene bisphosphonate analogs ("PCP-InsPs"). The conclusions that we draw from these data are interrogated by studying the impact upon catalytic activity upon mutagenesis of certain key residues. We present a picture of a V-shaped catalytic furrow with overhanging ridges constructed from flexible positively charged side chains; within this cavity, the labile phosphoanhydride bond is appropriately positioned at the catalytic site by an extensive series of interlocking polar contacts which we analogize as "suspension cables." We demonstrate functionality for a triglycine peptide within a β-strand which represents a non-canonical addition to the standard Nudix catalytic core structure. We describe pre-reaction enzyme/substrate states which we posit to reflect a role for electrostatic steering in substrate capture. Finally, through time-resolved analysis, we uncover a chronological sequence of DIPP1/product post-reaction states, one of which may rationalize a role for InsP6 as an inhibitor of catalytic activity.
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Affiliation(s)
- Guangning Zong
- Signal Transduction Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC, USA
| | - Nikolaus Jork
- Institute of Organic Chemistry, CIBSS - Center for Integrative Biological Signalling Studies, University of Freiburg, Freiburg, Germany
| | - Sarah Hostachy
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie, Berlin, Germany
| | - Dorothea Fiedler
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie, Berlin, Germany
| | - Henning J Jessen
- Institute of Organic Chemistry, CIBSS - Center for Integrative Biological Signalling Studies, University of Freiburg, Freiburg, Germany
| | - Stephen B Shears
- Signal Transduction Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC, USA
| | - Huanchen Wang
- Signal Transduction Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC, USA
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5
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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Li W, Lybrand DB, Xu H, Zhou F, Last RL, Pichersky E. A Trichome-Specific, Plastid-Localized Tanacetum cinerariifolium Nudix Protein Hydrolyzes the Natural Pyrethrin Pesticide Biosynthetic Intermediate trans-Chrysanthemyl Diphosphate. Front Plant Sci 2020; 11:482. [PMID: 32391039 PMCID: PMC7194074 DOI: 10.3389/fpls.2020.00482] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Accepted: 03/31/2020] [Indexed: 05/21/2023]
Abstract
Tanacetum cinerariifolium flowers synthesize six pyrethrins that function as effective insecticides. trans-Chrysanthemol is an early intermediate in the synthesis of the monoterpene moiety of pyrethrins. Previously, the pyrethrum enzyme chrysanthemyl diphosphate synthase (TcCDS) was shown to catalyze the formation of the prenyl diphosphate compound chrysanthemyl diphosphate (CPP) by condensing two molecules of dimethylallyl diphosphate (DMAPP). Later work also showed that with a low concentration of DMAPP, TcCDS can also remove the diphosphate group to give chrysanthemol. The removal of the phosphate groups from other prenyl diphosphates, such as DMAPP, isopentenyl diphosphate (IPP) and geranyl diphosphate (GPP), was previously shown to occur in two steps. In those cases, the first phosphate group is removed by a member of the Nudix hydrolase protein family, and the second by other unidentified phosphatases. These previously characterized Nudix proteins involved in the hydrolysis of prenyl diphosphates were shown to be cytosolic. Here we report that a plastidic Nudix protein from pyrethrum, designated TcNudix1, has high specificity for CPP and can hydrolyze it to chrysanthemol monophosphate (CMP). TcNudix1 is expressed specifically in the trichomes of the ovaries, where chrysanthemol is produced. TcNudix1 expression patterns and pathway reconstitution experiments presented here implicate the TcNudix1 protein in the biosynthesis of chrysanthemol.
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Affiliation(s)
- Wei Li
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI, United States
- Guangdong Laboratory for Lingnan Modern Agriculture, Genome Analysis Laboratory of the Ministry of Agriculture, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, China
| | - Daniel B. Lybrand
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, United States
| | - Haiyang Xu
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI, United States
- Center of Plant Functional Genomics, Institute of Advanced, Interdisciplinary Studies, Chongqing University, Chongqing, China
| | - Fei Zhou
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI, United States
| | - Robert L. Last
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, United States
- Department of Plant Biology, Michigan State University, East Lansing, MI, United States
| | - Eran Pichersky
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI, United States
- *Correspondence: Eran Pichersky,
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Abstract
The diphosphoinositol polyphosphate phosphohydrolases are a subset of the Nudix hydrolase family of enzymes. As such, they metabolize a wide range of substrates, including diphosphoinositol polyphosphates (inositol diphosphates, inositol pyrophosphates), dinucleotide phosphates, nucleosides as well as 5-phosphoribosyl 1-pyrophosphate and inorganic polyphosphate. Here, we describe protocols to optimize these enzymes, with consideration to buffer composition and sample preparation and how to analyze the metabolism of these substrates using high-performance liquid chromatography, giving advice where pitfalls are commonly encountered.
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Abstract
The Nudix hydrolase superfamily is identified by a conserved cassette of 23 amino acids, and it is characterized by its pyrophosphorylytic activity on a wide variety of nucleoside diphosphate derivatives. Of the 13 members of the family in Escherichia coli, only one, Orf180, has not been identified with a substrate, although a host of nucleoside diphosphate compounds has been tested. Several reports have noted a strong similarity in the three-dimensional structure of the unrelated enzyme, isopentenyl diphosphate isomerase (IDI) to the Nudix structure, and the report that a Nudix enzyme was involved in the synthesis of geraniol, a product of the two substrates of IDI, prompted an investigation of whether the IDI substrates, isopentenyl diphosphate (IPP), and dimethylallyl diphosphate (DAPP) could be substrates of Orf180. This article demonstrates that Orf180 does have a very low activity on IPP, DAPP, and geranyl pyrophosphate (GPP). However, several of the other Nudix enzymes with established nucleoside diphosphate substrates hydrolyze these compounds at substantial rates. In fact, some Nudix hydrolases have higher activities on IPP, DAPP, and GPP than on their signature nucleoside diphosphate derivatives.
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Affiliation(s)
- Maurice J. Bessman
- Department of BiologyJohns Hopkins UniversityBaltimoreMaryland21218‐2684
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9
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Abstract
The alarmone (p)ppGpp plays pivotal roles in basic bacterial stress responses by increasing tolerance of various nutritional limitations and chemical insults, including antibiotics. Despite intensive studies since (p)ppGpp was discovered over 4 decades ago, (p)ppGpp binding proteins have not been systematically identified in Escherichia coli. We applied DRaCALA (differential radial capillary action of ligand assay) to identify (p)ppGpp-protein interactions. We discovered 12 new (p)ppGpp targets in E. coli that, based on their physiological functions, could be classified into four major groups, involved in (i) purine nucleotide homeostasis (YgdH), (ii) ribosome biogenesis and translation (RsgA, Era, HflX, and LepA), (iii) maturation of dehydrogenases (HypB), and (iv) metabolism of (p)ppGpp (MutT, NudG, TrmE, NadR, PhoA, and UshA). We present a comprehensive and comparative biochemical and physiological characterization of these novel (p)ppGpp targets together with a comparative analysis of relevant, known (p)ppGpp binding proteins. Via this, primary targets of (p)ppGpp in E. coli are identified. The GTP salvage biosynthesis pathway and ribosome biogenesis and translation are confirmed as targets of (p)ppGpp that are highly conserved between E. coli and Firmicutes. In addition, an alternative (p)ppGpp degradative pathway, involving NudG and MutT, was uncovered. This report thus significantly expands the known cohort of (p)ppGpp targets in E. coli. Antibiotic resistance and tolerance exhibited by pathogenic bacteria have resulted in a global public health crisis. Remarkably, almost all bacterial pathogens require the alarmone (p)ppGpp to be virulent. Thus, (p)ppGpp not only induces tolerance of nutritional limitations and chemical insults, including antibiotics, but is also often required for induction of virulence genes. However, understanding of the molecular targets of (p)ppGpp and the mechanisms by which (p)ppGpp influences bacterial physiology is incomplete. In this study, a systematic approach was used to uncover novel targets of (p)ppGpp in E. coli, the best-studied model bacterium. Comprehensive comparative studies of the targets revealed conserved target pathways of (p)ppGpp in both Gram-positive and -negative bacteria and novel targets of (p)ppGpp, including an alternative degradative pathway of (p)ppGpp. Thus, our discoveries may help in understanding of how (p)ppGpp increases the stress resilience and multidrug tolerance not only of the model organism E. coli but also of the pathogenic organisms in which these targets are conserved.
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Hashiguchi K, Hayashi M, Sekiguchi M, Umezu K. The roles of human MTH1, MTH2 and MTH3 proteins in maintaining genome stability under oxidative stress. Mutat Res 2018; 808:10-19. [PMID: 29482072 DOI: 10.1016/j.mrfmmm.2018.01.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2017] [Revised: 12/26/2017] [Accepted: 01/13/2018] [Indexed: 11/16/2022]
Abstract
The hydrolysis of nucleotides containing 8-oxo-7,8-dihydroguanine (8-oxoG) is important in the maintenance of genome stability. Human cells possess three types of proteins, MTH1 (NUDT1), MTH2 (NUDT15) and MTH3 (NUDT18), which have the potential to hydrolyze deoxyribonucleoside di- and triphosphates containing 8-oxoG to the monophosphate, the form of which is unusable for DNA synthesis. To elucidate the physiological roles of these enzymes, we constructed single knockout (KO) cell lines for each of the MTH1, MTH2 and MTH3 genes and MTH1 and MTH2-double KO cell lines from the human HeLa S3 line using CRISPR/Cas9. With the exception of MTH3-KO, all of the KO cell lines showed similar proliferation rates to the parental line, HeLa S3, indicating that the MTH1 and MTH2 functions are dispensable for cell growth. On the other hand, the MTH3-KO cells showed a significantly slower growth rate, suggesting that MTH3 has a definite role in cell growth in addition to the cleavage of 8-oxoG-containing deoxyribonucleotide. MTH1-KO, MTH2-KO and MTH1- MTH2-KO cells exhibited increased sensitivity to hydrogen peroxide, whereas MTH3-KO did not. MTH1-KO cells showed only a slight increase in mutant frequency in comparison to the parental HeLa S3 line. The overproduction of MTH1 and MTH2 suppressed the mutator phenotype of mutT-deficient E. coli cells, whereas the overproduction of MTH3 did not show such a suppressive effect. Our findings suggest that both MTH1 and MTH2 are involved in the maintaining genome stability in human cells against oxidative stress, while MTH3 may play some other role(s).
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Affiliation(s)
- Kazunari Hashiguchi
- Department of Biochemistry, Fukuoka Dental College, Fukuoka 814-0193, Japan; Frontier Research Center, Fukuoka Dental College, Fukuoka 814-0193, Japan.
| | - Michio Hayashi
- Department of Biochemistry, Fukuoka Dental College, Fukuoka 814-0193, Japan
| | - Mutsuo Sekiguchi
- Frontier Research Center, Fukuoka Dental College, Fukuoka 814-0193, Japan
| | - Keiko Umezu
- Department of Biochemistry, Fukuoka Dental College, Fukuoka 814-0193, Japan
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11
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Abstract
The mammalian NUDT13 protein possesses a sequence motif characteristic of the NADH pyrophosphohydrolase subfamily of Nudix hydrolases. Due to the persistent insolubility of the recombinant product expressed in Escherichia coli, active mouse Nudt13 was expressed in insect cells from a baculovirus vector as a histidine-tagged recombinant protein. In vitro, it efficiently hydrolysed NADH to NMNH and AMP and NADPH to NMNH and 2',5'-ADP and had a marked preference for the reduced pyridine nucleotides. Much lower activity was obtained with other nucleotide substrates tested. K m and k cat values for NADH were 0.34 mM and 7 s-1 respectively. Expression of Nudt13 as an N-terminal fusion to green fluorescent protein revealed that it was targeted exclusively to mitochondria by the N-terminal targeting peptide, suggesting that Nudt13 may act to regulate the concentration of mitochondrial reduced pyridine nucleotide cofactors and the NAD(P)+/NAD(P)H ratio in this organelle and elsewhere. Future studies of the enzymology of pyridine nucleotide metabolism in relation to energy homeostasis, redox control, free radical production and cellular integrity should consider the possible regulatory role of Nudt13.
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Affiliation(s)
- Salama R Abdelraheim
- Department of Biochemistry, Institute of Integrative Biology, University of Liverpool, Liverpool, L69 7ZB, UK
- Department of Biochemistry, Faculty of Medicine, Minia University, Minia, 61519, Egypt
| | - David G Spiller
- Department of Biochemistry, Institute of Integrative Biology, University of Liverpool, Liverpool, L69 7ZB, UK
- Faculty of Biology, Medicine and Health, Systems Microscopy Centre, University of Manchester, Manchester, M13 9PT, UK
| | - Alexander G McLennan
- Department of Biochemistry, Institute of Integrative Biology, University of Liverpool, Liverpool, L69 7ZB, UK.
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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: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [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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13
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Bischler T, Hsieh PK, Resch M, Liu Q, Tan HS, Foley PL, Hartleib A, Sharma CM, Belasco JG. Identification of the RNA Pyrophosphohydrolase RppH of Helicobacter pylori and Global Analysis of Its RNA Targets. J Biol Chem 2016; 292:1934-1950. [PMID: 27974459 DOI: 10.1074/jbc.m116.761171] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2016] [Revised: 12/02/2016] [Indexed: 12/20/2022] Open
Abstract
RNA degradation is crucial for regulating gene expression in all organisms. Like the decapping of eukaryotic mRNAs, the conversion of the 5'-terminal triphosphate of bacterial transcripts to a monophosphate can trigger RNA decay by exposing the transcript to attack by 5'-monophosphate-dependent ribonucleases. In both biological realms, this deprotection step is catalyzed by members of the Nudix hydrolase family. The genome of the gastric pathogen Helicobacter pylori, a Gram-negative epsilonproteobacterium, encodes two proteins resembling Nudix enzymes. Here we present evidence that one of them, HP1228 (renamed HpRppH), is an RNA pyrophosphohydrolase that triggers RNA degradation in H. pylori, whereas the other, HP0507, lacks such activity. In vitro, HpRppH converts RNA 5'-triphosphates and diphosphates to monophosphates. It requires at least two unpaired nucleotides at the 5' end of its substrates and prefers three or more but has only modest sequence preferences. The influence of HpRppH on RNA degradation in vivo was examined by using RNA-seq to search the H. pylori transcriptome for RNAs whose 5'-phosphorylation state and cellular concentration are governed by this enzyme. Analysis of cDNA libraries specific for transcripts bearing a 5'-triphosphate and/or monophosphate revealed at least 63 potential HpRppH targets. These included mRNAs and sRNAs, several of which were validated individually by half-life measurements and quantification of their 5'-terminal phosphorylation state in wild-type and mutant cells. These findings demonstrate an important role for RppH in post-transcriptional gene regulation in pathogenic Epsilonproteobacteria and suggest a possible basis for the phenotypes of H. pylori mutants lacking this enzyme.
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Affiliation(s)
- Thorsten Bischler
- From the Research Center for Infectious Diseases, University of Würzburg, Josef-Schneider-Strasse 2/D15, 97080 Würzburg, Germany; the Institute of Molecular Infection Biology, University of Würzburg, Josef-Schneider-Strasse 2/D15, 97080 Würzburg, Germany and
| | - Ping-Kun Hsieh
- the Kimmel Center for Biology and Medicine at the Skirball Institute and the Department of Microbiology, New York University School of Medicine, New York, New York 10016
| | - Marcus Resch
- From the Research Center for Infectious Diseases, University of Würzburg, Josef-Schneider-Strasse 2/D15, 97080 Würzburg, Germany; the Institute of Molecular Infection Biology, University of Würzburg, Josef-Schneider-Strasse 2/D15, 97080 Würzburg, Germany and
| | - Quansheng Liu
- the Kimmel Center for Biology and Medicine at the Skirball Institute and the Department of Microbiology, New York University School of Medicine, New York, New York 10016
| | - Hock Siew Tan
- the Institute of Molecular Infection Biology, University of Würzburg, Josef-Schneider-Strasse 2/D15, 97080 Würzburg, Germany and
| | - Patricia L Foley
- the Kimmel Center for Biology and Medicine at the Skirball Institute and the Department of Microbiology, New York University School of Medicine, New York, New York 10016
| | - Anika Hartleib
- From the Research Center for Infectious Diseases, University of Würzburg, Josef-Schneider-Strasse 2/D15, 97080 Würzburg, Germany; the Institute of Molecular Infection Biology, University of Würzburg, Josef-Schneider-Strasse 2/D15, 97080 Würzburg, Germany and
| | - Cynthia M Sharma
- From the Research Center for Infectious Diseases, University of Würzburg, Josef-Schneider-Strasse 2/D15, 97080 Würzburg, Germany; the Institute of Molecular Infection Biology, University of Würzburg, Josef-Schneider-Strasse 2/D15, 97080 Würzburg, Germany and.
| | - Joel G Belasco
- the Kimmel Center for Biology and Medicine at the Skirball Institute and the Department of Microbiology, New York University School of Medicine, New York, New York 10016.
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14
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Nguyen VN, Park A, Xu A, Srouji JR, Brenner SE, Kirsch JF. Substrate specificity characterization for eight putative nudix hydrolases. Evaluation of criteria for substrate identification within the Nudix family. Proteins 2016; 84:1810-1822. [PMID: 27618147 PMCID: PMC5158307 DOI: 10.1002/prot.25163] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2016] [Revised: 08/30/2016] [Accepted: 09/06/2016] [Indexed: 11/16/2022]
Abstract
The nearly 50,000 known Nudix proteins have a diverse array of functions, of which the most extensively studied is the catalyzed hydrolysis of aberrant nucleotide triphosphates. The functions of 171 Nudix proteins have been characterized to some degree, although physiological relevance of the assayed activities has not always been conclusively demonstrated. We investigated substrate specificity for eight structurally characterized Nudix proteins, whose functions were unknown. These proteins were screened for hydrolase activity against a 74-compound library of known Nudix enzyme substrates. We found substrates for four enzymes with kcat /Km values >10,000 M-1 s-1 : Q92EH0_LISIN of Listeria innocua serovar 6a against ADP-ribose, Q5LBB1_BACFN of Bacillus fragilis against 5-Me-CTP, and Q0TTC5_CLOP1 and Q0TS82_CLOP1 of Clostridium perfringens against 8-oxo-dATP and 3'-dGTP, respectively. To ascertain whether these identified substrates were physiologically relevant, we surveyed all reported Nudix hydrolytic activities against NTPs. Twenty-two Nudix enzymes are reported to have activity against canonical NTPs. With a single exception, we find that the reported kcat /Km values exhibited against these canonical substrates are well under 105 M-1 s-1 . By contrast, several Nudix enzymes show much larger kcat /Km values (in the range of 105 to >107 M-1 s-1 ) against noncanonical NTPs. We therefore conclude that hydrolytic activities exhibited by these enzymes against canonical NTPs are not likely their physiological function, but rather the result of unavoidable collateral damage occasioned by the enzymes' inability to distinguish completely between similar substrate structures. Proteins 2016; 84:1810-1822. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Vi N. Nguyen
- Molecular and Cell Biology DepartmentUniversity of CaliforniaBerkeleyCalifornia94720
| | - Annsea Park
- Molecular and Cell Biology DepartmentUniversity of CaliforniaBerkeleyCalifornia94720
| | - Anting Xu
- Graduate Program in Comparative BiochemistryUniversity of CaliforniaBerkeleyCalifornia94720
| | - John R. Srouji
- Molecular and Cell Biology DepartmentUniversity of CaliforniaBerkeleyCalifornia94720
- Plant and Microbial Biology DepartmentUniversity of CaliforniaBerkeleyCalifornia94720
- Present address: Molecular and Cellular Biology DepartmentHarvard UniversityCambridgeMA02138
| | - Steven E. Brenner
- Molecular and Cell Biology DepartmentUniversity of CaliforniaBerkeleyCalifornia94720
- Graduate Program in Comparative BiochemistryUniversity of CaliforniaBerkeleyCalifornia94720
- Plant and Microbial Biology DepartmentUniversity of CaliforniaBerkeleyCalifornia94720
| | - Jack F. Kirsch
- Molecular and Cell Biology DepartmentUniversity of CaliforniaBerkeleyCalifornia94720
- Graduate Program in Comparative BiochemistryUniversity of CaliforniaBerkeleyCalifornia94720
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15
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O'Handley SF, Thirawatananond P, Kang LW, Cunningham JE, Leyva JA, Amzel LM, Gabelli SB. Kinetic and mutational studies of the adenosine diphosphate ribose hydrolase from Mycobacterium tuberculosis. J Bioenerg Biomembr 2016; 48:557-567. [PMID: 27683242 PMCID: PMC5489420 DOI: 10.1007/s10863-016-9681-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2016] [Accepted: 09/15/2016] [Indexed: 12/30/2022]
Abstract
Mycobacterium tuberculosis represents one of the world's most devastating infectious agents - with one third of the world's population infected and 1.5 million people dying each year from this deadly pathogen. As part of an effort to identify targets for therapeutic intervention, we carried out the kinetic characterization of the product of gene rv1700 of M. tuberculosis. Based on its sequence and its structure, the protein had been tentatively identified as a pyrophosphohydrolase specific for adenosine diphosphate ribose (ADPR), a compound involved in various pathways including oxidative stress response and tellurite resistance. In this work we carry out a kinetic, mutational and structural investigation of the enzyme, which provides a full characterization of this Mt-ADPRase. Optimal catalytic rates were achieved at alkaline pH (7.5-8.5) with either 0.5-1 mM Mg2+ or 0.02-1 mM Mn2+. K m and k cat values for hydrolysis of ADPR with Mg2+ ions are 200 ± 19 μM and 14.4 ± 0.4 s-1, and with Mn2+ ions are 554 ± 64 μM and 28.9 ± 1.4 s-1. Four residues proposed to be important in the catalytic mechanism of the enzyme were individually mutated and the kinetics of the mutant enzymes were characterized. In the four cases, the K m increased only slightly (2- to 3-fold) but the k cat decreased significantly (300- to 1900-fold), confirming the participation of these residues in catalysis. An analysis of the sequence and structure conservation patterns in Nudix ADPRases permits an unambiguous identification of members of the family and provides insight into residues involved in catalysis and their participation in substrate recognition in the Mt-ADPRase.
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Affiliation(s)
- Suzanne F O'Handley
- School of Chemistry and Materials Science, Rochester Institute of Technology, Rochester, NY, 14623, USA
| | - Puchong Thirawatananond
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
| | - Lin-Woo Kang
- Department of Biological Sciences, Konkuk University, Seoul, South Korea
| | - Jennifer E Cunningham
- School of Chemistry and Materials Science, Rochester Institute of Technology, Rochester, NY, 14623, USA
| | - J Alfonso Leyva
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
- Physics Department, Pontificia Universidad Javeriana, Bogotá, D.C., Colombia
| | - L Mario Amzel
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
| | - Sandra B Gabelli
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA.
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA.
- Department of Oncology, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA.
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Foley PL, Hsieh PK, Luciano DJ, Belasco JG. Specificity and evolutionary conservation of the Escherichia coli RNA pyrophosphohydrolase RppH. J Biol Chem 2015; 290:9478-86. [PMID: 25657006 DOI: 10.1074/jbc.m114.634659] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2014] [Indexed: 12/20/2022] Open
Abstract
Bacterial RNA degradation often begins with conversion of the 5'-terminal triphosphate to a monophosphate by the RNA pyrophosphohydrolase RppH, an event that triggers rapid ribonucleolytic attack. Besides its role as the master regulator of 5'-end-dependent mRNA decay, RppH is important for the ability of pathogenic bacteria to invade host cells, yet little is known about how it chooses its targets. Here, we show that Escherichia coli RppH (EcRppH) requires at least two unpaired nucleotides at the RNA 5' end and prefers three or more such nucleotides. It can tolerate any nucleotide at the first three positions but has a modest preference for A at the 5' terminus and either a G or A at the second position. Mutational analysis has identified EcRppH residues crucial for substrate recognition or catalysis. The promiscuity of EcRppH differentiates it from its Bacillus subtilis counterpart, which has a strict RNA sequence requirement. EcRppH orthologs likely to share its relaxed sequence specificity are widespread in all classes of Proteobacteria, except Deltaproteobacteria, and in flowering plants. By contrast, the phylogenetic range of recognizable B. subtilis RppH orthologs appears to be restricted to the order Bacillales. These findings help to explain the selective influence of RppH on bacterial mRNA decay and show that RppH-dependent degradation has diversified significantly during the course of evolution.
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Affiliation(s)
- Patricia L Foley
- From the Kimmel Center for Biology and Medicine at the Skirball Institute and the Department of Microbiology, New York University School of Medicine, New York, New York 10016
| | - Ping-kun Hsieh
- From the Kimmel Center for Biology and Medicine at the Skirball Institute and the Department of Microbiology, New York University School of Medicine, New York, New York 10016
| | - Daniel J Luciano
- From the Kimmel Center for Biology and Medicine at the Skirball Institute and the Department of Microbiology, New York University School of Medicine, New York, New York 10016
| | - Joel G Belasco
- From the Kimmel Center for Biology and Medicine at the Skirball Institute and the Department of Microbiology, New York University School of Medicine, New York, New York 10016
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Kilari RS, Weaver JD, Shears SB, Safrany ST. Understanding inositol pyrophosphate metabolism and function: kinetic characterization of the DIPPs. FEBS Lett 2013; 587:3464-70. [PMID: 24021644 DOI: 10.1016/j.febslet.2013.08.035] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2013] [Revised: 08/20/2013] [Accepted: 08/28/2013] [Indexed: 12/19/2022]
Abstract
We illuminate the metabolism and the cell-signaling activities of inositol pyrophosphates, by showing that regulation of yeast cyclin-kinase by 1-InsP7 is not conserved for mammalian CDK5, and by kinetically characterizing Ddp1p/DIPP-mediated dephosphorylation of 1-InsP7, 5-InsP7 and InsP8. Each phosphatase exhibited similar Km values for every substrate (range: 35-148 nM). The rank order of kcat values (1-InsP7>5-InsP7=InsP8) was identical for each enzyme, although DIPP1 was 10- to 60-fold more active than DIPP2α/β and DIPP3α/β. We demonstrate InsP8 dephosphorylation preferentially progresses through 1-InsP7. Conversely, we conclude that the more metabolically and functionally significant steady-state route of InsP8 synthesis proceeds via 5-InsP7.
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Affiliation(s)
- Rajagopal S Kilari
- Department of Pharmacy, Faculty of Science and Engineering, University of Wolverhampton, Wulfruna Street, Wolverhampton WV11LY, UK
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