1
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Gangopadhyay S, Das G, Gupta S, Ghosh A, Bagale SS, Roy PK, Mandal M, Harikrishna S, Sinha S, Gore KR. 4'- C-Acetamidomethyl-2'- O-methoxyethyl Nucleic Acid Modifications Improve Thermal Stability, Nuclease Resistance, Potency, and hAgo2 Binding of Small Interfering RNAs. J Org Chem 2024; 89:3747-3768. [PMID: 38394362 DOI: 10.1021/acs.joc.3c02506] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/25/2024]
Abstract
In this study, we designed the 4'-C-acetamidomethyl-2'-O-methoxyethyl (4'-C-ACM-2'-O-MOE) uridine and thymidine modifications, aiming to test them into small interfering RNAs. Thermal melting studies revealed that incorporating a single 4'-C-ACM-2'-O-MOE modification in the DNA duplex reduced thermal stability. In contrast, an increase in thermal stability was observed when the modification was introduced in DNA:RNA hybrid and in siRNAs. Thermal destabilization in DNA duplex was attributed to unfavorable entropy, which was mainly compensated by the enthalpy factor to some extent. A single 4'-C-ACM-2'-O-MOE thymidine modification at the penultimate position of the 3'-end of dT20 oligonucleotides in the presence of 3'-specific exonucleases, snake venom phosphodiesterase (SVPD), demonstrated significant stability as compared to monomer modifications including 2'-O-Me, 2'-O-MOE, and 2'-F. In gene silencing studies, we found that the 4'-C-ACM-2'-O-MOE uridine or thymidine modifications at the 3'-overhang in the passenger strand in combination with two 2'-F modifications exhibited superior RNAi activity. The results suggest that the dual modification is well tolerated at the 3'-end of the passenger strand, which reflects better siRNA stability and silencing activity. Interestingly, 4'-C-ACM-2'-O-MOE-modified siRNAs showed considerable gene silencing even after 96 h posttransfection; it showed that our modification could induce prolonged gene silencing due to improved metabolic stability. Molecular modeling studies revealed that the introduction of the 4'-C-ACM-2'-O-MOE modification at the 3'-end of the siRNA guide strand helps to anchor the strand within the PAZ domain of the hAgo2 protein. The overall results indicate that the 4'-C-ACM-2'-O-MOE uridine and thymidine modifications are promising modifications to improve the stability, potency, and hAgo2 binding of siRNAs.
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Affiliation(s)
- Sumit Gangopadhyay
- Department of Chemistry, Indian Institute of Technology Kharagpur, Kharagpur, West Bengal 721302, India
| | - Gourav Das
- Department of Chemistry, Indian Institute of Technology Kharagpur, Kharagpur, West Bengal 721302, India
| | - Shalini Gupta
- School of Applied and Interdisciplinary Sciences, Indian Association for the Cultivation of Science, Kolkata, Jadavpur 700032, India
| | - Atanu Ghosh
- School of Applied and Interdisciplinary Sciences, Indian Association for the Cultivation of Science, Kolkata, Jadavpur 700032, India
| | | | - Pritam Kumar Roy
- School of Medical Science and Technology, Indian Institute of Technology Kharagpur, Kharagpur, West Bengal 721302, India
| | - Mahitosh Mandal
- School of Medical Science and Technology, Indian Institute of Technology Kharagpur, Kharagpur, West Bengal 721302, India
| | - S Harikrishna
- Center for Structural Biology, Vanderbilt University, Nashville, Tennessee 37232, United States
| | - Surajit Sinha
- School of Applied and Interdisciplinary Sciences, Indian Association for the Cultivation of Science, Kolkata, Jadavpur 700032, India
| | - Kiran R Gore
- Department of Chemistry, Indian Institute of Technology Kharagpur, Kharagpur, West Bengal 721302, India
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2
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Sahoo A, Das G, Ghosh A, Shivappa Bagale S, Kumar Choudhary N, Harikrishna S, Sinha S, Gore KR. N 3-Methyluridine and 2'-O-Alkyl/2'-Fluoro-N 3-methyluridine functionalized nucleic acids improve nuclease resistance while maintaining duplex geometry. Bioorg Med Chem 2024; 100:117616. [PMID: 38295488 DOI: 10.1016/j.bmc.2024.117616] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2023] [Revised: 01/16/2024] [Accepted: 01/26/2024] [Indexed: 02/02/2024]
Abstract
Herein, we report the synthesis of 2'-O-alkyl/2'-fluoro-N3-methyluridine (2'-O-alkyl/2'-F-m3U) phosphoramidites and their incorporation in DNA and RNA oligonucleotides. The duplex binding affinity and base discrimination studies showed that all 2'-O-alkyl/2'-F-m3U modifications significantly decreased the thermal stability and base-pairing discrimination ability. Serum stability study of dT20 with 2'-O-alkyl-m3U modification exhibited excellent nuclease resistance when incubated with 3'-exonucleases (SVPD) or 5'-exonucleases (PDE-II) as compared to m3U, 2'-F, 2'-OMe modified oligonucleotides. MD simulation studies with RNA tetradecamer duplexes illustrated that the m3U and 2'-O-methyl-m3U modifications reduce the duplex stabilities by disrupting the Watson-Crick hydrogen bonding and base-stacking interactions. Further molecular modelling investigations demonstrated that the 2'-O-propyl-m3U modification exhibits steric interactions with amino acid residues in the active site of 3'- and 5'-exonuclease, leading to enhanced stability. These combined data indicate that the 2'-modified-m3U nucleotides can be used as a promising tool to enhance the stability, silencing efficiency, and drug-like properties of antisense/siRNA-based therapeutics.
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Affiliation(s)
- Avijit Sahoo
- Department of Chemistry, Indian Institute of Technology Kharagpur, West Bengal 721302, India
| | - Gourav Das
- Department of Chemistry, Indian Institute of Technology Kharagpur, West Bengal 721302, India
| | - Atanu Ghosh
- School of Applied and Interdisciplinary Sciences, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032, India
| | | | - Nishant Kumar Choudhary
- Department of Chemistry, Indian Institute of Technology Kharagpur, West Bengal 721302, India
| | - S Harikrishna
- Center for Structural Biology, Vanderbilt University, Nashville, TN 37232, United States
| | - Surajit Sinha
- School of Applied and Interdisciplinary Sciences, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032, India
| | - Kiran R Gore
- Department of Chemistry, Indian Institute of Technology Kharagpur, West Bengal 721302, India.
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3
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Shannon A, Chazot A, Feracci M, Falcou C, Fattorini V, Selisko B, Good S, Moussa A, Sommadossi JP, Ferron F, Alvarez K, Canard B. An exonuclease-resistant chain-terminating nucleotide analogue targeting the SARS-CoV-2 replicase complex. Nucleic Acids Res 2024; 52:1325-1340. [PMID: 38096103 PMCID: PMC10853775 DOI: 10.1093/nar/gkad1194] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Revised: 11/14/2023] [Accepted: 12/11/2023] [Indexed: 02/10/2024] Open
Abstract
Nucleotide analogues (NA) are currently employed for treatment of several viral diseases, including COVID-19. NA prodrugs are intracellularly activated to the 5'-triphosphate form. They are incorporated into the viral RNA by the viral polymerase (SARS-CoV-2 nsp12), terminating or corrupting RNA synthesis. For Coronaviruses, natural resistance to NAs is provided by a viral 3'-to-5' exonuclease heterodimer nsp14/nsp10, which can remove terminal analogues. Here, we show that the replacement of the α-phosphate of Bemnifosbuvir 5'-triphosphate form (AT-9010) by an α-thiophosphate renders it resistant to excision. The resulting α-thiotriphosphate, AT-9052, exists as two epimers (RP/SP). Through co-crystallization and activity assays, we show that the Sp isomer is preferentially used as a substrate by nucleotide diphosphate kinase (NDPK), and by SARS-CoV-2 nsp12, where its incorporation causes immediate chain-termination. The same -Sp isomer, once incorporated by nsp12, is also totally resistant to the excision by nsp10/nsp14 complex. However, unlike AT-9010, AT-9052-RP/SP no longer inhibits the N-terminal nucleotidylation domain of nsp12. We conclude that AT-9052-Sp exhibits a unique mechanism of action against SARS-CoV-2. Moreover, the thio modification provides a general approach to rescue existing NAs whose activity is hampered by coronavirus proofreading capacity.
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Affiliation(s)
- Ashleigh Shannon
- AFMB, CNRS, Aix-Marseille University, UMR 7257, Case 925, 163 Avenue de Luminy, 13288, Marseille Cedex 09, France
| | - Aurélie Chazot
- AFMB, CNRS, Aix-Marseille University, UMR 7257, Case 925, 163 Avenue de Luminy, 13288, Marseille Cedex 09, France
| | - Mikael Feracci
- AFMB, CNRS, Aix-Marseille University, UMR 7257, Case 925, 163 Avenue de Luminy, 13288, Marseille Cedex 09, France
| | - Camille Falcou
- AFMB, CNRS, Aix-Marseille University, UMR 7257, Case 925, 163 Avenue de Luminy, 13288, Marseille Cedex 09, France
| | - Véronique Fattorini
- AFMB, CNRS, Aix-Marseille University, UMR 7257, Case 925, 163 Avenue de Luminy, 13288, Marseille Cedex 09, France
| | - Barbara Selisko
- AFMB, CNRS, Aix-Marseille University, UMR 7257, Case 925, 163 Avenue de Luminy, 13288, Marseille Cedex 09, France
| | - Steven Good
- ATEA Pharmaceuticals, Inc., 225 Franklin St., Suite 2100, Boston, MA 02110, USA
| | - Adel Moussa
- ATEA Pharmaceuticals, Inc., 225 Franklin St., Suite 2100, Boston, MA 02110, USA
| | | | - François Ferron
- AFMB, CNRS, Aix-Marseille University, UMR 7257, Case 925, 163 Avenue de Luminy, 13288, Marseille Cedex 09, France
- European Virus Bioinformatics Center, Leutragraben 1, 07743 Jena, Germany
| | - Karine Alvarez
- AFMB, CNRS, Aix-Marseille University, UMR 7257, Case 925, 163 Avenue de Luminy, 13288, Marseille Cedex 09, France
| | - Bruno Canard
- AFMB, CNRS, Aix-Marseille University, UMR 7257, Case 925, 163 Avenue de Luminy, 13288, Marseille Cedex 09, France
- European Virus Bioinformatics Center, Leutragraben 1, 07743 Jena, Germany
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4
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Buchel G, Nayak AR, Herbine K, Sarfallah A, Sokolova VO, Zamudio-Ochoa A, Temiakov D. Structural basis for DNA proofreading. Nat Commun 2023; 14:8501. [PMID: 38151585 PMCID: PMC10752894 DOI: 10.1038/s41467-023-44198-8] [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: 08/03/2023] [Accepted: 12/04/2023] [Indexed: 12/29/2023] Open
Abstract
DNA polymerase (DNAP) can correct errors in DNA during replication by proofreading, a process critical for cell viability. However, the mechanism by which an erroneously incorporated base translocates from the polymerase to the exonuclease site and the corrected DNA terminus returns has remained elusive. Here, we present an ensemble of nine high-resolution structures representing human mitochondrial DNA polymerase Gamma, Polγ, captured during consecutive proofreading steps. The structures reveal key events, including mismatched base recognition, its dissociation from the polymerase site, forward translocation of DNAP, alterations in DNA trajectory, repositioning and refolding of elements for primer separation, DNAP backtracking, and displacement of the mismatched base into the exonuclease site. Altogether, our findings suggest a conserved 'bolt-action' mechanism of proofreading based on iterative cycles of DNAP translocation without dissociation from the DNA, facilitating primer transfer between catalytic sites. Functional assays and mutagenesis corroborate this mechanism, connecting pathogenic mutations to crucial structural elements in proofreading steps.
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Affiliation(s)
- Gina Buchel
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, 1020 Locust St, Philadelphia, PA, 19107, USA
| | - Ashok R Nayak
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, 1020 Locust St, Philadelphia, PA, 19107, USA
| | - Karl Herbine
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, 1020 Locust St, Philadelphia, PA, 19107, USA
| | - Azadeh Sarfallah
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, 1020 Locust St, Philadelphia, PA, 19107, USA
| | - Viktoriia O Sokolova
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, 1020 Locust St, Philadelphia, PA, 19107, USA
| | - Angelica Zamudio-Ochoa
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, 1020 Locust St, Philadelphia, PA, 19107, USA
| | - Dmitry Temiakov
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, 1020 Locust St, Philadelphia, PA, 19107, USA.
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5
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Betancurt-Anzola L, Martínez-Carranza M, Delarue M, Zatopek KM, Gardner AF, Sauguet L. Molecular basis for proofreading by the unique exonuclease domain of Family-D DNA polymerases. Nat Commun 2023; 14:8306. [PMID: 38097591 PMCID: PMC10721889 DOI: 10.1038/s41467-023-44125-x] [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: 08/09/2023] [Accepted: 11/30/2023] [Indexed: 12/17/2023] Open
Abstract
Replicative DNA polymerases duplicate entire genomes at high fidelity. This feature is shared among the three domains of life and is facilitated by their dual polymerase and exonuclease activities. Family D replicative DNA polymerases (PolD), found exclusively in Archaea, contain an unusual RNA polymerase-like catalytic core, and a unique Mre11-like proofreading active site. Here, we present cryo-EM structures of PolD trapped in a proofreading mode, revealing an unanticipated correction mechanism that extends the repertoire of protein domains known to be involved in DNA proofreading. Based on our experimental structures, mutants of PolD were designed and their contribution to mismatch bypass and exonuclease kinetics was determined. This study sheds light on the convergent evolution of structurally distinct families of DNA polymerases, and the domain acquisition and exchange mechanism that occurred during the evolution of the replisome in the three domains of life.
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Affiliation(s)
- Leonardo Betancurt-Anzola
- Architecture and Dynamics of Biological Macromolecules, Institut Pasteur, Université Paris Cité, CNRS, UMR 3528, Paris, France
- New England Biolabs Inc., 240 County Road, Ipswich, MA, 01938, USA
- New England Biolabs France, 5 Rue Henri Auguste Desbruères, 91000, Évry-Courcouronnes, France
- Sorbonne Université, Collège Doctoral, ED 515, Paris, France
| | - Markel Martínez-Carranza
- Architecture and Dynamics of Biological Macromolecules, Institut Pasteur, Université Paris Cité, CNRS, UMR 3528, Paris, France
| | - Marc Delarue
- Architecture and Dynamics of Biological Macromolecules, Institut Pasteur, Université Paris Cité, CNRS, UMR 3528, Paris, France
| | - Kelly M Zatopek
- New England Biolabs Inc., 240 County Road, Ipswich, MA, 01938, USA.
| | - Andrew F Gardner
- New England Biolabs Inc., 240 County Road, Ipswich, MA, 01938, USA.
| | - Ludovic Sauguet
- Architecture and Dynamics of Biological Macromolecules, Institut Pasteur, Université Paris Cité, CNRS, UMR 3528, Paris, France.
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6
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Egli M. Robert Letsinger and the Evolution of Oligonucleotide Synthesis. ACS OMEGA 2023; 8:32222-32230. [PMID: 37720801 PMCID: PMC10500693 DOI: 10.1021/acsomega.3c05177] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Accepted: 08/16/2023] [Indexed: 09/19/2023]
Abstract
This retrospective summarizes a presentation given at the symposium "Bob Letsinger, PhD-100 Years of History" on September 28, 2021 as part of the 17th annual meeting of the Oligonucleotide Therapeutics Society (OTS). In it I look back at my encounters with Robert Lewis Letsinger (1921-2014) while at Northwestern University as Assistant Professor between 1995 and 2000.
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Affiliation(s)
- Martin Egli
- Department of Biochemistry, Center
for Structural Biology and Vanderbilt Ingram Cancer Center, Vanderbilt University, School of Medicine, Nashville, Tennessee 37232, United States
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7
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Genna V, Iglesias-Fernández J, Reyes-Fraile L, Villegas N, Guckian K, Seth P, Wan B, Cabrero C, Terrazas M, Brun-Heath I, González C, Sciabola S, Villalobos A, Orozco M. Controlled sulfur-based engineering confers mouldability to phosphorothioate antisense oligonucleotides. Nucleic Acids Res 2023; 51:4713-4725. [PMID: 37099382 PMCID: PMC10250214 DOI: 10.1093/nar/gkad309] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Revised: 04/04/2023] [Accepted: 04/24/2023] [Indexed: 04/27/2023] Open
Abstract
Phosphorothioates (PS) have proven their effectiveness in the area of therapeutic oligonucleotides with applications spanning from cancer treatment to neurodegenerative disorders. Initially, PS substitution was introduced for the antisense oligonucleotides (PS ASOs) because it confers an increased nuclease resistance meanwhile ameliorates cellular uptake and in-vivo bioavailability. Thus, PS oligonucleotides have been elevated to a fundamental asset in the realm of gene silencing therapeutic methodologies. But, despite their wide use, little is known on the possibly different structural changes PS-substitutions may provoke in DNA·RNA hybrids. Additionally, scarce information and significant controversy exists on the role of phosphorothioate chirality in modulating PS properties. Here, through comprehensive computational investigations and experimental measurements, we shed light on the impact of PS chirality in DNA-based antisense oligonucleotides; how the different phosphorothioate diastereomers impact DNA topology, stability and flexibility to ultimately disclose pro-Sp S and pro-Rp S roles at the catalytic core of DNA Exonuclease and Human Ribonuclease H; two major obstacles in ASOs-based therapies. Altogether, our results provide full-atom and mechanistic insights on the structural aberrations PS-substitutions provoke and explain the origin of nuclease resistance PS-linkages confer to DNA·RNA hybrids; crucial information to improve current ASOs-based therapies.
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Affiliation(s)
- Vito Genna
- Mechanisms of Diseases, Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Baldiri Reixac 10-12, Barcelona 08028, Spain
- NBD | Nostrum Biodiscovery, Baldiri Reixac 10, Barcelona 08028, Spain
| | | | - Laura Reyes-Fraile
- Mechanisms of Diseases, Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Baldiri Reixac 10-12, Barcelona 08028, Spain
| | - Nuria Villegas
- Mechanisms of Diseases, Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Baldiri Reixac 10-12, Barcelona 08028, Spain
| | | | - Punit Seth
- Ionis Pharmaceuticals Inc., 2855 Gazelle Court, Carlsbad, CA 92010, USA
| | - Brad Wan
- Ionis Pharmaceuticals Inc., 2855 Gazelle Court, Carlsbad, CA 92010, USA
| | - Cristina Cabrero
- Instituto de Química Física Rocasolano, C/ Serrano 119, Madrid 28006, Spain
| | - Montserrat Terrazas
- Mechanisms of Diseases, Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Baldiri Reixac 10-12, Barcelona 08028, Spain
- Department of Inorganic and Organic Chemistry, Section of Organic Chemistry, IBUB, University of Barcelona, Martí i Franquès 1-11, 08028 Barcelona, Spain
| | - Isabelle Brun-Heath
- Mechanisms of Diseases, Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Baldiri Reixac 10-12, Barcelona 08028, Spain
| | - Carlos González
- Instituto de Química Física Rocasolano, C/ Serrano 119, Madrid 28006, Spain
| | | | | | - Modesto Orozco
- Mechanisms of Diseases, Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Baldiri Reixac 10-12, Barcelona 08028, Spain
- Department of Biochemistry and Biomedicine, University of Barcelona, Barcelona 08028, Spain
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8
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Hariharan VN, Caiazzi J, Miller R, Ferguson C, Sapp E, Fakih H, Tang Q, Yamada N, Furgal R, Paquette J, Bramato B, McHugh N, Summers A, Lochmann C, Godinho B, Hildebrand S, Echeverria D, Hassler M, Alterman J, DiFiglia M, Aronin N, Khvorova A, Yamada K. Extended Nucleic Acid (exNA): A Novel, Biologically Compatible Backbone that Significantly Enhances Oligonucleotide Efficacy in vivo. RESEARCH SQUARE 2023:rs.3.rs-2987323. [PMID: 37398145 PMCID: PMC10312934 DOI: 10.21203/rs.3.rs-2987323/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/04/2023]
Abstract
Metabolic stabilization of therapeutic oligonucleotides requires both sugar and backbone modifications, where phosphorothioate (PS) is the only backbone chemistry used in the clinic. Here, we describe the discovery, synthesis, and characterization of a novel biologically compatible backbone, extended nucleic acid (exNA). Upon exNA precursor scale up, exNA incorporation is fully compatible with common nucleic acid synthetic protocols. The novel backbone is orthogonal to PS and shows profound stabilization against 3'- and 5'-exonucleases. Using small interfering RNAs (siRNAs) as an example, we show exNA is tolerated at most nucleotide positions and profoundly improves in vivo efficacy. A combined exNA-PS backbone enhances siRNA resistance to serum 3'-exonuclease by ~ 32-fold over PS backbone and > 1000-fold over the natural phosphodiester backbone, thereby enhancing tissue exposure (~ 6-fold), tissues accumulation (4- to 20-fold), and potency both systemically and in brain. The improved potency and durability imparted by exNA opens more tissues and indications to oligonucleotide-driven therapeutic interventions.
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Affiliation(s)
| | | | | | - Chantal Ferguson
- RNA Therapeutics Institute, University of Massachusetts Medical School
| | | | | | - Qi Tang
- University of Massachusetts Chan Medical School
| | | | | | | | | | - Nicholas McHugh
- RNA Therapeutics Institute, University of Massachusetts Medical School
| | | | | | - Bruno Godinho
- RNA Therapeutics Institute, University of Massachusetts Medical School
| | - Samuel Hildebrand
- RNA Therapeutics Institute, University of Massachusetts Medical School
| | - Dimas Echeverria
- RNA Therapeutics Institute, University of Massachusetts Medical School
| | | | | | | | - Neil Aronin
- University of Massachusetts Worcester Campus
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9
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Yamada K, Hariharan VN, Caiazzi J, Miller R, Furguson C, Sapp E, Fakih H, Tan Q, Yamada N, Furgal RC, Paquette J, Bramato B, McHugh N, Summers A, Lochmann C, Godinho BM, Hildebrand S, Echeverria D, Hassler MR, Alterman JF, DiFiglia M, Aronin N, Khvorova A. Extended Nucleic Acid (exNA): A Novel, Biologically Compatible Backbone that Significantly Enhances Oligonucleotide Efficacy in vivo. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.26.542506. [PMID: 37292886 PMCID: PMC10245983 DOI: 10.1101/2023.05.26.542506] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Metabolic stabilization of therapeutic oligonucleotides requires both sugar and backbone modifications, where phosphorothioate (PS) is the only backbone chemistry used in the clinic. Here, we describe the discovery, synthesis, and characterization of a novel biologically compatible backbone, extended nucleic acid (exNA). Upon exNA precursor scale up, exNA incorporation is fully compatible with common nucleic acid synthetic protocols. The novel backbone is orthogonal to PS and shows profound stabilization against 3'- and 5'-exonucleases. Using small interfering RNAs (siRNAs) as an example, we show exNA is tolerated at most nucleotide positions and profoundly improves in vivo efficacy. A combined exNA-PS backbone enhances siRNA resistance to serum 3'-exonuclease by ~32-fold over PS backbone and >1000-fold over the natural phosphodiester backbone, thereby enhancing tissue exposure (~6-fold), tissues accumulation (4- to 20-fold), and potency both systemically and in brain. The improved potency and durability imparted by exNA opens more tissues and indications to oligonucleotide-driven therapeutic interventions.
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Affiliation(s)
- Ken Yamada
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School, 368 Plantation Street, Worcester, Massachusetts 01605, United States
| | - Vignesh Narayan Hariharan
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School, 368 Plantation Street, Worcester, Massachusetts 01605, United States
| | - Jillian Caiazzi
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School, 368 Plantation Street, Worcester, Massachusetts 01605, United States
| | - Rachael Miller
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School, 368 Plantation Street, Worcester, Massachusetts 01605, United States
- Department of Medicine, University of Massachusetts Chan Medical School; Charlestown, Massachusetts, United State
| | - Chantal Furguson
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School, 368 Plantation Street, Worcester, Massachusetts 01605, United States
- Department of Medicine, University of Massachusetts Chan Medical School; Charlestown, Massachusetts, United State
| | - Ellen Sapp
- Department of Neurology, Harvard Medical School and Mass General Institute for Neurodegenerative Disease, Charlestown, Massachusetts, United State
| | - Hassan Fakih
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School, 368 Plantation Street, Worcester, Massachusetts 01605, United States
| | - Qi Tan
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School, 368 Plantation Street, Worcester, Massachusetts 01605, United States
| | - Nozomi Yamada
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School, 368 Plantation Street, Worcester, Massachusetts 01605, United States
| | - Raymond C. Furgal
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School, 368 Plantation Street, Worcester, Massachusetts 01605, United States
| | - Joseph Paquette
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School, 368 Plantation Street, Worcester, Massachusetts 01605, United States
- Department of Medicine, University of Massachusetts Chan Medical School; Charlestown, Massachusetts, United State
| | - Brianna Bramato
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School, 368 Plantation Street, Worcester, Massachusetts 01605, United States
| | - Nicholas McHugh
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School, 368 Plantation Street, Worcester, Massachusetts 01605, United States
| | - Ashley Summers
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School, 368 Plantation Street, Worcester, Massachusetts 01605, United States
| | - Clemens Lochmann
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School, 368 Plantation Street, Worcester, Massachusetts 01605, United States
| | - Bruno M.D.C. Godinho
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School, 368 Plantation Street, Worcester, Massachusetts 01605, United States
| | - Samuel Hildebrand
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School, 368 Plantation Street, Worcester, Massachusetts 01605, United States
| | - Dimas Echeverria
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School, 368 Plantation Street, Worcester, Massachusetts 01605, United States
| | - Matthew R. Hassler
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School, 368 Plantation Street, Worcester, Massachusetts 01605, United States
| | - Julia F. Alterman
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School, 368 Plantation Street, Worcester, Massachusetts 01605, United States
| | - Marian DiFiglia
- Department of Neurology, Harvard Medical School and Mass General Institute for Neurodegenerative Disease, Charlestown, Massachusetts, United State
| | - Neil Aronin
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School, 368 Plantation Street, Worcester, Massachusetts 01605, United States
- Department of Medicine, University of Massachusetts Chan Medical School; Charlestown, Massachusetts, United State
| | - Anastasia Khvorova
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School, 368 Plantation Street, Worcester, Massachusetts 01605, United States
- Program in Molecular Medicine, University of Massachusetts Chan Medical School; Charlestown, Massachusetts, United State
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10
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Chinthapatla R, Sotoudegan M, Srivastava P, Anderson TK, Moustafa I, Passow K, Kennelly S, Moorthy R, Dulin D, Feng J, Harki D, Kirchdoerfer R, Cameron C, Arnold J. Interfering with nucleotide excision by the coronavirus 3'-to-5' exoribonuclease. Nucleic Acids Res 2023; 51:315-336. [PMID: 36546762 PMCID: PMC9841423 DOI: 10.1093/nar/gkac1177] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Revised: 11/11/2022] [Accepted: 11/27/2022] [Indexed: 12/24/2022] Open
Abstract
Some of the most efficacious antiviral therapeutics are ribonucleos(t)ide analogs. The presence of a 3'-to-5' proofreading exoribonuclease (ExoN) in coronaviruses diminishes the potency of many ribonucleotide analogs. The ability to interfere with ExoN activity will create new possibilities for control of SARS-CoV-2 infection. ExoN is formed by a 1:1 complex of nsp14 and nsp10 proteins. We have purified and characterized ExoN using a robust, quantitative system that reveals determinants of specificity and efficiency of hydrolysis. Double-stranded RNA is preferred over single-stranded RNA. Nucleotide excision is distributive, with only one or two nucleotides hydrolyzed in a single binding event. The composition of the terminal basepair modulates excision. A stalled SARS-CoV-2 replicase in complex with either correctly or incorrectly terminated products prevents excision, suggesting that a mispaired end is insufficient to displace the replicase. Finally, we have discovered several modifications to the 3'-RNA terminus that interfere with or block ExoN-catalyzed excision. While a 3'-OH facilitates hydrolysis of a nucleotide with a normal ribose configuration, this substituent is not required for a nucleotide with a planar ribose configuration such as that present in the antiviral nucleotide produced by viperin. Design of ExoN-resistant, antiviral ribonucleotides should be feasible.
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Affiliation(s)
- Rukesh Chinthapatla
- Department of Microbiology and Immunology, The University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC 27599, USA
| | - Mohamad Sotoudegan
- Department of Microbiology and Immunology, The University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC 27599, USA
| | - Pankaj Srivastava
- Department of Microbiology and Immunology, The University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC 27599, USA
| | - Thomas K Anderson
- Department of Biochemistry and Institute for Molecular Virology, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Ibrahim M Moustafa
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA 16802, USA
| | - Kellan T Passow
- Department of Medicinal Chemistry, University of Minnesota, Minneapolis, MN 55455, USA
| | - Samantha A Kennelly
- Department of Medicinal Chemistry, University of Minnesota, Minneapolis, MN 55455, USA
| | - Ramkumar Moorthy
- Department of Medicinal Chemistry, University of Minnesota, Minneapolis, MN 55455, USA
| | - David Dulin
- Department of Physics and Astronomy, and LaserLaB Amsterdam, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
- Junior Research Group 2, Interdisciplinary Center for Clinical Research, Friedrich-Alexander-University Erlangen-Nürnberg (FAU), Cauerstr. 3, 91058 Erlangen, Germany
| | - Joy Y Feng
- Gilead Sciences, Inc, Foster City, CA 94404, USA
| | - Daniel A Harki
- Department of Medicinal Chemistry, University of Minnesota, Minneapolis, MN 55455, USA
| | - Robert N Kirchdoerfer
- Department of Biochemistry and Institute for Molecular Virology, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Craig E Cameron
- Department of Microbiology and Immunology, The University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC 27599, USA
| | - Jamie J Arnold
- Department of Microbiology and Immunology, The University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC 27599, USA
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11
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Kinetics of DNA strand transfer between polymerase and proofreading exonuclease active sites regulates error correction during high-fidelity replication. J Biol Chem 2022; 299:102744. [PMID: 36436560 PMCID: PMC9800556 DOI: 10.1016/j.jbc.2022.102744] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Revised: 11/18/2022] [Accepted: 11/20/2022] [Indexed: 11/25/2022] Open
Abstract
We show that T7 DNA polymerase (pol) and exonuclease (exo) domains contribute to selective error correction during DNA replication by regulating bidirectional strand transfer between the two active sites. To explore the kinetic basis for selective removal of mismatches, we used a fluorescent cytosine analog (1,3-diaza-2-oxophenoxazine) to monitor the kinetics of DNA transfer between the exo and pol sites. We globally fit stopped-flow fluorescence and base excision kinetic data and compared results obtained with ssDNA versus duplex DNA to resolve how DNA transfer governs exo specificity. We performed parallel studies using hydrolysis-resistant phosphorothioate oligonucleotides to monitor DNA transfer to the exo site without hydrolysis. ssDNA binds to the exo site at the diffusion limit (109 M-1 s-1, Kd = 40 nM) followed by fast hydrolysis of the 3'-terminal nucleotide (>5000 s-1). Analysis using duplex DNA with a 3'-terminal mismatch or a buried mismatch exposed a unique intermediate state between pol and exo active sites and revealed that transfer via the intermediate to the exo site is stimulated by free nucleoside triphosphates. Transfer from the exo site back to the pol site after cleavage is fast and efficient. We propose a model to explain why buried mismatches are removed faster than single 3'-terminal mismatches and thereby provide an additional opportunity for error correction. Our data provide the first comprehensive model to explain how DNA transfer from pol to exo active sites and back again after base excision allow efficient selective mismatch removal during DNA replication to improve fidelity by more than 1000-fold.
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12
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De Serres-Bérard T, Ait Benichou S, Jauvin D, Boutjdir M, Puymirat J, Chahine M. Recent Progress and Challenges in the Development of Antisense Therapies for Myotonic Dystrophy Type 1. Int J Mol Sci 2022; 23:13359. [PMID: 36362145 PMCID: PMC9657934 DOI: 10.3390/ijms232113359] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2022] [Revised: 10/20/2022] [Accepted: 10/25/2022] [Indexed: 08/01/2023] Open
Abstract
Myotonic dystrophy type 1 (DM1) is a dominant genetic disease in which the expansion of long CTG trinucleotides in the 3' UTR of the myotonic dystrophy protein kinase (DMPK) gene results in toxic RNA gain-of-function and gene mis-splicing affecting mainly the muscles, the heart, and the brain. The CUG-expanded transcripts are a suitable target for the development of antisense oligonucleotide (ASO) therapies. Various chemical modifications of the sugar-phosphate backbone have been reported to significantly enhance the affinity of ASOs for RNA and their resistance to nucleases, making it possible to reverse DM1-like symptoms following systemic administration in different transgenic mouse models. However, specific tissue delivery remains to be improved to achieve significant clinical outcomes in humans. Several strategies, including ASO conjugation to cell-penetrating peptides, fatty acids, or monoclonal antibodies, have recently been shown to improve potency in muscle and cardiac tissues in mice. Moreover, intrathecal administration of ASOs may be an advantageous complementary administration route to bypass the blood-brain barrier and correct defects of the central nervous system in DM1. This review describes the evolution of the chemical design of antisense oligonucleotides targeting CUG-expanded mRNAs and how recent advances in the field may be game-changing by forwarding laboratory findings into clinical research and treatments for DM1 and other microsatellite diseases.
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Affiliation(s)
- Thiéry De Serres-Bérard
- CERVO Research Center, Institut Universitaire en Santé Mentale de Québec, Quebec City, QC G1J 2G3, Canada
| | - Siham Ait Benichou
- LOEX, CHU de Québec-Université Laval Research Center, Quebec City, QC G1J 1Z4, Canada
| | - Dominic Jauvin
- CERVO Research Center, Institut Universitaire en Santé Mentale de Québec, Quebec City, QC G1J 2G3, Canada
| | - Mohamed Boutjdir
- Cardiovascular Research Program, VA New York Harbor Healthcare System, New York, NY 11209, USA
- Department of Medicine, Cell Biology and Pharmacology, State University of New York Downstate Health Science University, New York, NY 11203, USA
- Department of Medicine, NYU School of Medicine, New York, NY 10016, USA
| | - Jack Puymirat
- LOEX, CHU de Québec-Université Laval Research Center, Quebec City, QC G1J 1Z4, Canada
- Department of Medicine, Faculty of Medicine, Université Laval, Quebec City, QC G1V 0A6, Canada
| | - Mohamed Chahine
- CERVO Research Center, Institut Universitaire en Santé Mentale de Québec, Quebec City, QC G1J 2G3, Canada
- Department of Medicine, Faculty of Medicine, Université Laval, Quebec City, QC G1V 0A6, Canada
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13
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Chinthapatla R, Sotoudegan M, Anderson T, Moustafa IM, Passow KT, Kennelly SA, Moorthy R, Dulin D, Feng JY, Harki DA, Kirchdoerfer R, Cameron CE, Arnold JJ. Interfering with nucleotide excision by the coronavirus 3'-to-5' exoribonuclease. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2022:2022.08.11.503614. [PMID: 35982684 PMCID: PMC9387131 DOI: 10.1101/2022.08.11.503614] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Some of the most efficacious antiviral therapeutics are ribonucleos(t)ide analogs. The presence of a 3'-to-5' proofreading exoribonuclease (ExoN) in coronaviruses diminishes the potency of many ribonucleotide analogs. The ability to interfere with ExoN activity will create new possibilities for control of SARS-CoV-2 infection. ExoN is formed by a 1:1 complex of nsp14 and nsp10 proteins. We have purified and characterized ExoN using a robust, quantitative system that reveals determinants of specificity and efficiency of hydrolysis. Double-stranded RNA is preferred over single-stranded RNA. Nucleotide excision is distributive, with only one or two nucleotides hydrolyzed in a single binding event. The composition of the terminal basepair modulates excision. A stalled SARS-CoV-2 replicase in complex with either correctly or incorrectly terminated products prevents excision, suggesting that a mispaired end is insufficient to displace the replicase. Finally, we have discovered several modifications to the 3'-RNA terminus that interfere with or block ExoN-catalyzed excision. While a 3'-OH facilitates hydrolysis of a nucleotide with a normal ribose configuration, this substituent is not required for a nucleotide with a planar ribose configuration such as that present in the antiviral nucleotide produced by viperin. Design of ExoN-resistant, antiviral ribonucleotides should be feasible.
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Affiliation(s)
- Rukesh Chinthapatla
- Department of Microbiology and Immunology, The University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC 27599, USA
| | - Mohamad Sotoudegan
- Department of Microbiology and Immunology, The University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC 27599, USA
| | - Thomas Anderson
- Department of Biochemistry and Institute of Molecular Virology, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Ibrahim M. Moustafa
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA 16802, USA
| | - Kellan T. Passow
- Department of Medicinal Chemistry, University of Minnesota, Minneapolis, MN 55455, USA
| | - Samantha A. Kennelly
- Department of Medicinal Chemistry, University of Minnesota, Minneapolis, MN 55455, USA
| | - Ramkumar Moorthy
- Department of Medicinal Chemistry, University of Minnesota, Minneapolis, MN 55455, USA
| | - David Dulin
- Department of Physics and Astronomy, and LaserLaB Amsterdam, Vrije Universiteit Amsterdam, Amsterdam, Netherlands
- Junior Research Group 2, Interdisciplinary Center for Clinical Research, Friedrich-Alexander-University Erlangen-Nürnberg (FAU), Cauerstr. 3, 91058 Erlangen, Germany
| | - Joy Y. Feng
- Gilead Sciences, Inc, Foster City, CA 94404, USA
| | - Daniel A. Harki
- Department of Medicinal Chemistry, University of Minnesota, Minneapolis, MN 55455, USA
| | - Robert Kirchdoerfer
- Department of Biochemistry and Institute of Molecular Virology, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Craig E. Cameron
- Department of Microbiology and Immunology, The University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC 27599, USA
| | - Jamie J. Arnold
- Department of Microbiology and Immunology, The University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC 27599, USA
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14
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Guenther DC, Mori S, Matsuda S, Gilbert JA, Willoughby JLS, Hyde S, Bisbe A, Jiang Y, Agarwal S, Madaoui M, Janas MM, Charisse K, Maier MA, Egli M, Manoharan M. Role of a "Magic" Methyl: 2'-Deoxy-2'-α-F-2'-β- C-methyl Pyrimidine Nucleotides Modulate RNA Interference Activity through Synergy with 5'-Phosphate Mimics and Mitigation of Off-Target Effects. J Am Chem Soc 2022; 144:14517-14534. [PMID: 35921401 PMCID: PMC9389587 DOI: 10.1021/jacs.2c01679] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
![]()
Although 2′-deoxy-2′-α-F-2′-β-C-methyl (2′-F/Me) uridine nucleoside derivatives
are a successful class of antiviral drugs, this modification had not
been studied in oligonucleotides. Herein, we demonstrate the facile
synthesis of 2′-F/Me-modified pyrimidine phosphoramidites and
their subsequent incorporation into oligonucleotides. Despite the
C3′-endo preorganization of the parent nucleoside,
a single incorporation into RNA or DNA resulted in significant thermal
destabilization of a duplex due to unfavorable enthalpy, likely resulting
from steric effects. When located at the terminus of an oligonucleotide,
the 2′-F/Me modification imparted more resistance to degradation
than the corresponding 2′-fluoro nucleotides. Small interfering
RNAs (siRNAs) modified at certain positions with 2′-F/Me had
similar or better silencing activity than the parent siRNAs when delivered
via a lipid nanoparticle formulation or as a triantennary N-acetylgalactosamine conjugate in cells and in mice. Modification
in the seed region of the antisense strand at position 6 or 7 resulted
in an activity equivalent to the parent in mice. Additionally, placement
of the antisense strand at position 7 mitigated seed-based off-target
effects in cell-based assays. When the 2′-F/Me modification
was combined with 5′-vinyl phosphonate, both E and Z isomers had silencing activity comparable
to the parent. In combination with other 2′-modifications such
as 2′-O-methyl, the Z isomer
is detrimental to silencing activity. Presumably, the equivalence
of 5′-vinyl phosphonate isomers in the context of 2′-F/Me
is driven by the steric and conformational features of the C-methyl-containing sugar ring. These data indicate that
2′-F/Me nucleotides are promising tools for nucleic acid-based
therapeutic applications to increase potency, duration, and safety.
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Affiliation(s)
- Dale C Guenther
- Alnylam Pharmaceuticals, 675 West Kendall, Cambridge, Massachusetts 02142, United States
| | - Shohei Mori
- Alnylam Pharmaceuticals, 675 West Kendall, Cambridge, Massachusetts 02142, United States
| | - Shigeo Matsuda
- Alnylam Pharmaceuticals, 675 West Kendall, Cambridge, Massachusetts 02142, United States
| | - Jason A Gilbert
- Alnylam Pharmaceuticals, 675 West Kendall, Cambridge, Massachusetts 02142, United States
| | | | - Sarah Hyde
- Alnylam Pharmaceuticals, 675 West Kendall, Cambridge, Massachusetts 02142, United States
| | - Anna Bisbe
- Alnylam Pharmaceuticals, 675 West Kendall, Cambridge, Massachusetts 02142, United States
| | - Yongfeng Jiang
- Alnylam Pharmaceuticals, 675 West Kendall, Cambridge, Massachusetts 02142, United States
| | - Saket Agarwal
- Alnylam Pharmaceuticals, 675 West Kendall, Cambridge, Massachusetts 02142, United States
| | - Mimouna Madaoui
- Alnylam Pharmaceuticals, 675 West Kendall, Cambridge, Massachusetts 02142, United States
| | - Maja M Janas
- Alnylam Pharmaceuticals, 675 West Kendall, Cambridge, Massachusetts 02142, United States
| | - Klaus Charisse
- Alnylam Pharmaceuticals, 675 West Kendall, Cambridge, Massachusetts 02142, United States
| | - Martin A Maier
- Alnylam Pharmaceuticals, 675 West Kendall, Cambridge, Massachusetts 02142, United States
| | - Martin Egli
- Department of Biochemistry, School of Medicine, Vanderbilt University, Nashville, Tennessee 37232, United States
| | - Muthiah Manoharan
- Alnylam Pharmaceuticals, 675 West Kendall, Cambridge, Massachusetts 02142, United States
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15
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Jamsen JA, Shock DD, Wilson SH. Watching right and wrong nucleotide insertion captures hidden polymerase fidelity checkpoints. Nat Commun 2022; 13:3193. [PMID: 35680862 PMCID: PMC9184648 DOI: 10.1038/s41467-022-30141-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Accepted: 04/19/2022] [Indexed: 12/26/2022] Open
Abstract
Efficient and accurate DNA synthesis is enabled by DNA polymerase fidelity checkpoints that promote insertion of the right instead of wrong nucleotide. Erroneous X-family polymerase (pol) λ nucleotide insertion leads to genomic instability in double strand break and base-excision repair. Here, time-lapse crystallography captures intermediate catalytic states of pol λ undergoing right and wrong natural nucleotide insertion. The revealed nucleotide sensing mechanism responds to base pair geometry through active site deformation to regulate global polymerase-substrate complex alignment in support of distinct optimal (right) or suboptimal (wrong) reaction pathways. An induced fit during wrong but not right insertion, and associated metal, substrate, side chain and pyrophosphate reaction dynamics modulated nucleotide insertion. A third active site metal hastened right but not wrong insertion and was not essential for DNA synthesis. The previously hidden fidelity checkpoints uncovered reveal fundamental strategies of polymerase DNA repair synthesis in genomic instability. DNA polymerase (pol) λ performs DNA synthesis in base excision and double strand break repair. How pol λ accomplishes nucleotide insertion that can lead to mutagenesis and genomic instability was unclear. Here the authors employ time-lapse crystallography to reveal hidden polymerase checkpoints that enable right and wrong natural nucleotide insertion by pol λ.
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Affiliation(s)
- Joonas A Jamsen
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC, 27709, USA.
| | - David D Shock
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC, 27709, USA
| | - Samuel H Wilson
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC, 27709, USA.
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16
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Li J, Wan H, Zhang H, Wang XL, Liu G, Wu G, He X, Deng Z, Zhao YL. Molecular recognition between bacterial phosphorothioate DNA and sulfur-binding domain (SBD): competition between the water cage and chalcogen-hydrophobic packet. Phys Chem Chem Phys 2022; 24:9176-9187. [PMID: 35383346 DOI: 10.1039/d2cp00291d] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Bacterial DNA phosphorothioation (PT) physiologically and stereo-specifically replaces a non-bridging oxygen in a phosphate link with a sulfur atom, which can be recognized by a highly conserved sulfur-binding domain (SBD). Here we conducted thermodynamic integration (TI), molecular dynamics simulation, and quantum chemical calculations to decipher the specific molecular interactions between PT-DNA and SBD in Streptomyces coelicolor type IV restriction enzyme ScoMcrA. The TI-calculated binding affinity of (5'-CCGRp-PSGCCGG-3')2 is larger than that of (5'-CCGGCCGG-3')2 by about 7.4-7.7 kcal mol-1. The binding difference dominantly stems from hydration energy of non-phosphorothioate DNA (9.8-10.6 kcal mol-1) in aqueous solution, despite the persistent preference of 2.6-3.2 kcal mol-1 in the DNA-SBD MD simulations. Furthermore, the quantum chemical calculations reveal an unusual non-covalent interaction in the phosphorothioate-binding scenario, where the PS⋯NP165 chalcogen bond prevails the PS⋯HCβ vdW interactions from the adjacent residues H116-R117-Y164-P165-A168. Thus, the chalcogen-hydrophobic interaction pulls PT-DNA into the SBD binding pocket while the water cage pulls a normal DNA molecule out. The synergetic mechanism suggests the special roles of the proline pyrrolidine group in the SBD proteins, consistent with the experimental observations in the X-ray crystallography and structural bioinformatics analysis.
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Affiliation(s)
- Jiayi Li
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, China.
| | - Haibo Wan
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, China.
| | - Haoqing Zhang
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, China.
| | - Xiao-Lei Wang
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, China.
| | - Guang Liu
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, China.
| | - Geng Wu
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, China.
| | - Xinyi He
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, China.
| | - Zixin Deng
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, China.
| | - Yi-Lei Zhao
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, China.
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17
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Hunsicker-Wang LM, Vogt MJ, Hoogstraten CG, Cosper NJ, Davenport AM, Hendon CH, Scott RA, Britt RD, DeRose VJ. Spectroscopic characterization of Mn2+ and Cd2+ coordination to phosphorothioates in the conserved A9 metal site of the hammerhead ribozyme. J Inorg Biochem 2022; 230:111754. [DOI: 10.1016/j.jinorgbio.2022.111754] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Revised: 01/28/2022] [Accepted: 02/04/2022] [Indexed: 11/25/2022]
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18
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Dangerfield TL, Kirmizialtin S, Johnson KA. Substrate specificity and proposed structure of the proofreading complex of T7 DNA polymerase. J Biol Chem 2022; 298:101627. [PMID: 35074426 PMCID: PMC8867116 DOI: 10.1016/j.jbc.2022.101627] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Revised: 01/18/2022] [Accepted: 01/19/2022] [Indexed: 11/25/2022] Open
Abstract
Faithful replication of genomic DNA by high-fidelity DNA polymerases is crucial for the survival of most living organisms. While high-fidelity DNA polymerases favor canonical base pairs over mismatches by a factor of ∼1 × 105, fidelity is further enhanced several orders of magnitude by a 3′–5′ proofreading exonuclease that selectively removes mispaired bases in the primer strand. Despite the importance of proofreading to maintaining genome stability, it remains much less studied than the fidelity mechanisms employed at the polymerase active site. Here we characterize the substrate specificity for the proofreading exonuclease of a high-fidelity DNA polymerase by investigating the proofreading kinetics on various DNA substrates. The contribution of the exonuclease to net fidelity is a function of the kinetic partitioning between extension and excision. We show that while proofreading of a terminal mismatch is efficient, proofreading a mismatch buried by one or two correct bases is even more efficient. Because the polymerase stalls after incorporation of a mismatch and after incorporation of one or two correct bases on top of a mismatch, the net contribution of the exonuclease is a function of multiple opportunities to correct mistakes. We also characterize the exonuclease stereospecificity using phosphorothioate-modified DNA, provide a homology model for the DNA primer strand in the exonuclease active site, and propose a dynamic structural model for the transfer of DNA from the polymerase to the exonuclease active site based on MD simulations.
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Affiliation(s)
- Tyler L Dangerfield
- Department of Molecular Biosciences, Institute for Cellular and Molecular Biology, University of Texas, Austin, Texas, USA
| | - Serdal Kirmizialtin
- Chemistry Program, Science Division, New York University Abu Dhabi, Abu Dhabi, United Arab Emirates.
| | - Kenneth A Johnson
- Department of Molecular Biosciences, Institute for Cellular and Molecular Biology, University of Texas, Austin, Texas, USA.
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19
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Mikami A, Erande N, Matsuda S, Kel'in A, Woods LB, Chickering T, Pallan PS, Schlegel MK, Zlatev I, Egli M, Manoharan M. Synthesis, chirality-dependent conformational and biological properties of siRNAs containing 5'-(R)- and 5'-(S)-C-methyl-guanosine. Nucleic Acids Res 2020; 48:10101-10124. [PMID: 32990754 PMCID: PMC7544225 DOI: 10.1093/nar/gkaa750] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Revised: 08/10/2020] [Accepted: 08/27/2020] [Indexed: 12/22/2022] Open
Abstract
Various chemical modifications have been identified that enhance potency of small interfering RNAs (siRNAs) and that reduce off-target effects, immune stimulation, and toxicities of metabolites of these therapeutic agents. We previously described 5′-C-methyl pyrimidine nucleotides also modified at the 2′ position of the sugar. Here, we describe the synthesis of 2′-position unmodified 5′-(R)- and 5′-(S)-C-methyl guanosine and evaluation of these nucleotides in the context of siRNA. The (R) isomer provided protection from 5′ exonuclease and the (S) isomer provided protection from 3′ exonuclease in the context of a terminally modified oligonucleotide. siRNA potency was maintained when these modifications were incorporated at the tested positions of sense and antisense strands. Moreover, the corresponding 5′ triphosphates were not substrates for mitochondrial DNA polymerase. Models generated based on crystal structures of 5′ and 3′ exonuclease oligonucleotide complexes with 5′-(R)- and 5′-(S)-C-methyl substituents attached to the 5′- and 3′-terminal nucleotides, respectively, provided insight into the origins of the observed protections. Structural properties of 5′-(R)-C-methyl guanosine incorporated into an RNA octamer were analysed by X-ray crystallography, and the structure explains the loss in duplex thermal stability for the (R) isomer compared with the (S) isomer. Finally, the effect of 5′-C-methylation on endoribonuclease activity has been explained.
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Affiliation(s)
- Atsushi Mikami
- Alnylam Pharmaceuticals, 675 West Kendall Street, Cambridge, Massachusetts 02142, USA
| | - Namrata Erande
- Alnylam Pharmaceuticals, 675 West Kendall Street, Cambridge, Massachusetts 02142, USA
| | - Shigeo Matsuda
- Alnylam Pharmaceuticals, 675 West Kendall Street, Cambridge, Massachusetts 02142, USA
| | - Alexander Kel'in
- Alnylam Pharmaceuticals, 675 West Kendall Street, Cambridge, Massachusetts 02142, USA
| | - Lauren Blair Woods
- Alnylam Pharmaceuticals, 675 West Kendall Street, Cambridge, Massachusetts 02142, USA
| | - Tyler Chickering
- Alnylam Pharmaceuticals, 675 West Kendall Street, Cambridge, Massachusetts 02142, USA
| | - Pradeep S Pallan
- Department of Biochemistry Vanderbilt University, School of Medicine Nashville, TN 37232, USA
| | - Mark K Schlegel
- Alnylam Pharmaceuticals, 675 West Kendall Street, Cambridge, Massachusetts 02142, USA
| | - Ivan Zlatev
- Alnylam Pharmaceuticals, 675 West Kendall Street, Cambridge, Massachusetts 02142, USA
| | - Martin Egli
- Department of Biochemistry Vanderbilt University, School of Medicine Nashville, TN 37232, USA
| | - Muthiah Manoharan
- Alnylam Pharmaceuticals, 675 West Kendall Street, Cambridge, Massachusetts 02142, USA
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20
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Kumar P, Degaonkar R, Guenther DC, Abramov M, Schepers G, Capobianco M, Jiang Y, Harp J, Kaittanis C, Janas MM, Castoreno A, Zlatev I, Schlegel MK, Herdewijn P, Egli M, Manoharan M. Chimeric siRNAs with chemically modified pentofuranose and hexopyranose nucleotides: altritol-nucleotide (ANA) containing GalNAc-siRNA conjugates: in vitro and in vivo RNAi activity and resistance to 5'-exonuclease. Nucleic Acids Res 2020; 48:4028-4040. [PMID: 32170309 PMCID: PMC7192627 DOI: 10.1093/nar/gkaa125] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Revised: 02/15/2020] [Accepted: 03/04/2020] [Indexed: 12/23/2022] Open
Abstract
In this report, we investigated the hexopyranose chemical modification Altriol Nucleic Acid (ANA) within small interfering RNA (siRNA) duplexes that were otherwise fully modified with the 2′-deoxy-2′-fluoro and 2′-O-methyl pentofuranose chemical modifications. The siRNAs were designed to silence the transthyretin (Ttr) gene and were conjugated to a trivalent N-acetylgalactosamine (GalNAc) ligand for targeted delivery to hepatocytes. Sense and antisense strands of the parent duplex were synthesized with single ANA residues at each position on the strand, and the resulting siRNAs were evaluated for their ability to inhibit Ttr mRNA expression in vitro. Although ANA residues were detrimental at the 5′ end of the antisense strand, the siRNAs with ANA at position 6 or 7 in the seed region had activity comparable to the parent. The siRNA with ANA at position 7 in the seed region was active in a mouse model. An Oligonucleotide with ANA at the 5′ end was more stable in the presence of 5′-exonuclease than an oligonucleotide of the same sequence and chemical composition without the ANA modification. Modeling studies provide insight into the origins of regiospecific changes in potency of siRNAs and the increased protection against 5′-exonuclease degradation afforded by the ANA modification.
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Affiliation(s)
- Pawan Kumar
- Alnylam Pharmaceuticals, 300 Third Street, Cambridge, MA 02142, USA
| | - Rohan Degaonkar
- Alnylam Pharmaceuticals, 300 Third Street, Cambridge, MA 02142, USA
| | - Dale C Guenther
- Alnylam Pharmaceuticals, 300 Third Street, Cambridge, MA 02142, USA
| | - Mikhail Abramov
- Medicinal Chemistry, Rega Institute for Medical Research, KU Leuven, Herestraat 49, 3000 Leuven, Belgium
| | - Guy Schepers
- Medicinal Chemistry, Rega Institute for Medical Research, KU Leuven, Herestraat 49, 3000 Leuven, Belgium
| | - Marie Capobianco
- Alnylam Pharmaceuticals, 300 Third Street, Cambridge, MA 02142, USA
| | - Yongfeng Jiang
- Alnylam Pharmaceuticals, 300 Third Street, Cambridge, MA 02142, USA
| | - Joel Harp
- Department of Biochemistry, School of Medicine, Vanderbilt University, Nashville, TN 37232, USA
| | | | - Maja M Janas
- Alnylam Pharmaceuticals, 300 Third Street, Cambridge, MA 02142, USA
| | - Adam Castoreno
- Alnylam Pharmaceuticals, 300 Third Street, Cambridge, MA 02142, USA
| | - Ivan Zlatev
- Alnylam Pharmaceuticals, 300 Third Street, Cambridge, MA 02142, USA
| | - Mark K Schlegel
- Alnylam Pharmaceuticals, 300 Third Street, Cambridge, MA 02142, USA
| | - Piet Herdewijn
- Medicinal Chemistry, Rega Institute for Medical Research, KU Leuven, Herestraat 49, 3000 Leuven, Belgium
| | - Martin Egli
- Department of Biochemistry, School of Medicine, Vanderbilt University, Nashville, TN 37232, USA
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21
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The proofreading activity of Pfprex from Plasmodium falciparum can prevent mutagenesis of the apicoplast genome by oxidized nucleotides. Sci Rep 2020; 10:11157. [PMID: 32636411 PMCID: PMC7341739 DOI: 10.1038/s41598-020-67853-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Accepted: 06/11/2020] [Indexed: 01/28/2023] Open
Abstract
The DNA polymerase module of the Pfprex enzyme (PfpPol) is responsible for duplication of the genome of the apicoplast organelle in the malaria parasite. We show that PfpPol can misincorporate oxidized nucleotides such as 8oxodGTP opposite dA. This event gives rise to transversion mutations that are known to lead to adverse physiological outcomes. The apicoplast genome is particularly vulnerable to the harmful effects of 8oxodGTP due to very high AT content (~ 87%). We show that the proofreading activity of PfpPol has the unique ability to remove the oxidized nucleotide from the primer terminus. Due to this property, the proofreading domain of PfpPol is able to prevent mutagenesis of the AT-rich apicoplast genome and neutralize the deleterious genotoxic effects of ROS generated in the apicoplast due to normal metabolic processes. The proofreading activity of the Pfprex enzyme may, therefore, represent an attractive target for therapeutic intervention. Also, a survey of DNA repair pathways shows that the observed property of Pfprex constitutes a novel form of dynamic error correction wherein the repair of promutagenic damaged nucleotides is concomitant with DNA replication.
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22
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Park J, Lee SY, Jeong H, Kang MG, Van Haute L, Minczuk M, Seo JK, Jun Y, Myung K, Rhee HW, Lee C. The structure of human EXD2 reveals a chimeric 3' to 5' exonuclease domain that discriminates substrates via metal coordination. Nucleic Acids Res 2020; 47:7078-7093. [PMID: 31127291 PMCID: PMC6648332 DOI: 10.1093/nar/gkz454] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Revised: 05/07/2019] [Accepted: 05/10/2019] [Indexed: 12/24/2022] Open
Abstract
EXD2 (3′-5′ exonuclease domain-containing protein 2) is an essential protein with a conserved DEDDy superfamily 3′-5′ exonuclease domain. Recent research suggests that EXD2 has two potential functions: as a component of the DNA double-strand break repair machinery and as a ribonuclease for the regulation of mitochondrial translation. Herein, electron microscope imaging analysis and proximity labeling revealed that EXD2 is anchored to the mitochondrial outer membrane through a conserved N-terminal transmembrane domain, while the C-terminal region is cytosolic. Crystal structures of the exonuclease domain in complex with Mn2+/Mg2+ revealed a domain-swapped dimer in which the central α5−α7 helices are mutually crossed over, resulting in chimeric active sites. Additionally, the C-terminal segments absent in other DnaQ family exonucleases enclose the central chimeric active sites. Combined structural and biochemical analyses demonstrated that the unusual dimeric organization stabilizes the active site, facilitates discrimination between DNA and RNA substrates based on divalent cation coordination and generates a positively charged groove that binds substrates.
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Affiliation(s)
- Jumi Park
- Department of Biological Sciences, School of Life Sciences, Ulsan National Institute of Science and Technology, 50 UNIST-gil, Ulsan 44919, Republic of Korea.,Cell Logistics Research Center, Gwangju Institute of Science and Technology, Gwangju 61005, Republic of Korea
| | - Song-Yi Lee
- Department of Chemistry, Ulsan National Institute of Science and Technology, 50 UNIST-gil, Ulsan 44919, Republic of Korea.,Department of Chemistry, Seoul National University, Seoul 08826, Republic of Korea
| | - Hanbin Jeong
- Department of Biological Sciences, School of Life Sciences, Ulsan National Institute of Science and Technology, 50 UNIST-gil, Ulsan 44919, Republic of Korea.,Cell Logistics Research Center, Gwangju Institute of Science and Technology, Gwangju 61005, Republic of Korea
| | - Myeong-Gyun Kang
- Department of Chemistry, Ulsan National Institute of Science and Technology, 50 UNIST-gil, Ulsan 44919, Republic of Korea
| | - Lindsey Van Haute
- MRC Mitochondrial Biology Unit, University of Cambridge, Cambridge CB2 0XY, UK
| | - Michal Minczuk
- MRC Mitochondrial Biology Unit, University of Cambridge, Cambridge CB2 0XY, UK
| | - Jeong Kon Seo
- UNIST Central Research Facilities (UCRF), Ulsan National Institute of Science and Technology, 50 UNIST-gil, Ulsan 44919, Republic of Korea
| | - Youngsoo Jun
- School of Life Sciences, Gwangju Institute of Science and Technology, Gwangju 61005, Republic of Korea.,Cell Logistics Research Center, Gwangju Institute of Science and Technology, Gwangju 61005, Republic of Korea
| | - Kyungjae Myung
- Department of Biological Sciences, School of Life Sciences, Ulsan National Institute of Science and Technology, 50 UNIST-gil, Ulsan 44919, Republic of Korea.,Center for Genomic Integrity, Institute for Basic Science (IBS), Ulsan 44919, Republic of Korea
| | - Hyun-Woo Rhee
- Department of Chemistry, Seoul National University, Seoul 08826, Republic of Korea
| | - Changwook Lee
- Department of Biological Sciences, School of Life Sciences, Ulsan National Institute of Science and Technology, 50 UNIST-gil, Ulsan 44919, Republic of Korea.,Cell Logistics Research Center, Gwangju Institute of Science and Technology, Gwangju 61005, Republic of Korea.,Center for Genomic Integrity, Institute for Basic Science (IBS), Ulsan 44919, Republic of Korea
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23
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Foster BM, Rosenberg D, Salvo H, Stephens KL, Bintz BJ, Hammel M, Ellenberger T, Gainey MD, Wallen JR. Combined Solution and Crystal Methods Reveal the Electrostatic Tethers That Provide a Flexible Platform for Replication Activities in the Bacteriophage T7 Replisome. Biochemistry 2019; 58:4466-4479. [PMID: 31659895 DOI: 10.1021/acs.biochem.9b00525] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Recent structural studies of the bacteriophage T7 DNA replication system have shed light on how multiple proteins assemble to copy two antiparallel DNA strands. In T7, acidic C-terminal tails of both the primase-helicase and single-stranded DNA binding protein bind to two basic patches on the DNA polymerase to aid in replisome assembly, processivity, and coordinated DNA synthesis. Although these electrostatic interactions are essential for DNA replication, the molecular details for how these tails bind the polymerase are unknown. We have determined an X-ray crystal structure of the T7 DNA polymerase bound to both a primer/template DNA and a peptide that mimics the C-terminal tail of the primase-helicase. The structure reveals that the essential C-terminal phenylalanine of the tail binds to a hydrophobic pocket that is surrounded by positive charge on the surface of the polymerase. We show that alterations of polymerase residues that engage the tail lead to defects in viral replication. In the structure, we also observe dTTP bound in the exonuclease active site and stacked against tryptophan 160. Using both primer/extension assays and high-throughput sequencing, we show how mutations in the exonuclease active site lead to defects in mismatch repair and an increase in the level of mutagenesis of the T7 genome. Finally, using small-angle X-ray scattering, we provide the first solution structures of a complex between the single-stranded DNA binding protein and the DNA polymerase and show how a single-stranded DNA binding protein dimer engages both one and two copies of DNA polymerase.
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Affiliation(s)
- Brittni M Foster
- Department of Chemistry & Physics , Western Carolina University , Cullowhee , North Carolina 28723 , United States
| | - Daniel Rosenberg
- Molecular Biophysics and Integrated Bioimaging , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States.,Graduate Group in Biophysics , University of California, Berkeley , Berkeley , California 94720 , United States
| | - Henry Salvo
- Department of Chemistry & Physics , Western Carolina University , Cullowhee , North Carolina 28723 , United States
| | - Kasie L Stephens
- Department of Chemistry & Physics , Western Carolina University , Cullowhee , North Carolina 28723 , United States
| | - Brittania J Bintz
- Department of Chemistry & Physics , Western Carolina University , Cullowhee , North Carolina 28723 , United States
| | - Michal Hammel
- Molecular Biophysics and Integrated Bioimaging , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
| | - Tom Ellenberger
- Department of Biochemistry and Molecular Biophysics , Washington University School of Medicine , St. Louis , Missouri 63110 , United States
| | - Maria D Gainey
- Department of Chemistry & Physics , Western Carolina University , Cullowhee , North Carolina 28723 , United States
| | - Jamie R Wallen
- Department of Chemistry & Physics , Western Carolina University , Cullowhee , North Carolina 28723 , United States
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24
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An updated structural classification of replicative DNA polymerases. Biochem Soc Trans 2019; 47:239-249. [PMID: 30647142 DOI: 10.1042/bst20180579] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Revised: 11/30/2018] [Accepted: 12/07/2018] [Indexed: 12/13/2022]
Abstract
Replicative DNA polymerases are nano-machines essential to life, which have evolved the ability to copy the genome with high fidelity and high processivity. In contrast with cellular transcriptases and ribosome machines, which evolved by accretion of complexity from a conserved catalytic core, no replicative DNA polymerase is universally conserved. Strikingly, four different families of DNA polymerases have evolved to perform DNA replication in the three domains of life. In Bacteria, the genome is replicated by DNA polymerases belonging to the A- and C-families. In Eukarya, genomic DNA is copied mainly by three distinct replicative DNA polymerases, Polα, Polδ, and Polε, which all belong to the B-family. Matters are more complicated in Archaea, which contain an unusual D-family DNA polymerase (PolD) in addition to PolB, a B-family replicative DNA polymerase that is homologous to the eukaryotic ones. PolD is a heterodimeric DNA polymerase present in all Archaea discovered so far, except Crenarchaea. While PolD is an essential replicative DNA polymerase, it is often underrepresented in the literature when the diversity of DNA polymerases is discussed. Recent structural studies have shown that the structures of both polymerase and proofreading active sites of PolD differ from other structurally characterized DNA polymerases, thereby extending the repertoire of folds known to perform DNA replication. This review aims to provide an updated structural classification of all replicative DNAPs and discuss their evolutionary relationships, both regarding the DNA polymerase and proofreading active sites.
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25
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Gu R, Oweida T, Yingling YG, Chilkoti A, Zauscher S. Enzymatic Synthesis of Nucleobase-Modified Single-Stranded DNA Offers Tunable Resistance to Nuclease Degradation. Biomacromolecules 2018; 19:3525-3535. [PMID: 30011192 DOI: 10.1021/acs.biomac.8b00816] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
We synthesized long, nucleobase-modified, single-stranded DNA (ssDNA) using terminal deoxynucleotidyl transferase (TdT) enzymatic polymerization. Specifically, we investigated the effect of unnatural nucleobase size and incorporation density on ssDNA resistance to exo- and endonuclease degradation. We discovered that increasing the size and density of unnatural nucleobases enhances ssDNA resistance to degradation in the presence of exonuclease I, DNase I, and human serum. We also studied the mechanism of this resistance enhancement using molecular dynamics simulations. Our results show that the presence of unnatural nucleobases in ssDNA decreases local chain flexibility and hampers nuclease access to the ssDNA backbone, which hinders nuclease binding to ssDNA and slows its degradation. Our discoveries suggest that incorporating nucleobase-modified nucleotides into ssDNA, using enzymatic polymerization, is an easy and efficient strategy to prolong and tune the half-life of DNA-based materials in nucleases-containing environments.
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Affiliation(s)
| | - Thomas Oweida
- Department of Materials Science and Engineering , North Carolina State University , Raleigh , North Carolina 27695 , United States
| | - Yaroslava G Yingling
- Department of Materials Science and Engineering , North Carolina State University , Raleigh , North Carolina 27695 , United States
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26
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Sato S, Miyanaga A, Kim SY, Kuzuyama T, Kudo F, Eguchi T. Biochemical and Structural Analysis of FomD That Catalyzes the Hydrolysis of Cytidylyl ( S)-2-Hydroxypropylphosphonate in Fosfomycin Biosynthesis. Biochemistry 2018; 57:4858-4866. [PMID: 30010320 DOI: 10.1021/acs.biochem.8b00690] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In fosfomycin biosynthesis, the hydrolysis of cytidylyl ( S)-2-hydroxypropylphosphonate [( S)-HPP-CMP] to afford ( S)-HPP is the only uncharacterized step. Because FomD is an uncharacterized protein with a DUF402 domain that is encoded in the fosfomycin biosynthetic gene cluster, FomD was hypothesized to be responsible for this reaction. In this study, FomD was found to hydrolyze ( S)-HPP-CMP to give ( S)-HPP and CMP efficiently in the presence of Mn2+ or Co2+. FomD also hydrolyzed cytidylyl 2-hydroxyethylphosphonate (HEP-CMP), which is a biosynthetic intermediate before C-methylation. The kcat/ KM value of FomD with ( S)-HPP-CMP was 10-fold greater than that with HEP-CMP, suggesting that FomD hydrolyzes ( S)-HPP-CMP rather than HEP-CMP in bacteria. The crystal structure of FomD showed that this protein adopts a barrel-like fold, which consists of a large twisted antiparallel β-sheet. This is a key structural feature of the DUF402 domain-containing proteins. Two metal cations are located between the FomD barrel and the two α-helices at the C-terminus and serve to presumably activate the phosphonate group of substrates for hydrolysis. Docking simulations with ( S)-HPP-CMP suggested that the methyl group at the C2 position of the HPP moiety is recognized by a hydrophobic interaction with Trp68. Further mutational analysis suggested that a conserved Tyr107 among the DUF402 domain family of proteins activates a water molecule to promote nucleophilic attack on the phosphorus atom of the phosphonate moiety. These findings provide mechanistic insights into the FomD reaction and lead to a complete understanding of the fosfomycin biosynthetic pathway in Streptomyces.
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Affiliation(s)
- Shusuke Sato
- Department of Chemistry , Tokyo Institute of Technology , 2-12-1 O-okayama , Meguro-ku, Tokyo 152-8551 , Japan
| | - Akimasa Miyanaga
- Department of Chemistry , Tokyo Institute of Technology , 2-12-1 O-okayama , Meguro-ku, Tokyo 152-8551 , Japan
| | | | | | - Fumitaka Kudo
- Department of Chemistry , Tokyo Institute of Technology , 2-12-1 O-okayama , Meguro-ku, Tokyo 152-8551 , Japan
| | - Tadashi Eguchi
- Department of Chemistry , Tokyo Institute of Technology , 2-12-1 O-okayama , Meguro-ku, Tokyo 152-8551 , Japan
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27
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Yu HLL, Maslova A, Hsing IM. Rational Design of Electrochemical DNA Biosensors for Point-of-Care Applications. ChemElectroChem 2017. [DOI: 10.1002/celc.201600756] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Henson L. Lee Yu
- Department of Chemical and Biomolecular Engineering; The Hong Kong University of Science and Technology; Clear Water Bay Kowloon, Hong Kong SAR
| | - Anastasia Maslova
- Division of Biomedical Engineering; The Hong Kong University of Science and Technology; Clear Water Bay Kowloon, Hong Kong SAR
| | - I-Ming Hsing
- Department of Chemical and Biomolecular Engineering; The Hong Kong University of Science and Technology; Clear Water Bay Kowloon, Hong Kong SAR
- Division of Biomedical Engineering; The Hong Kong University of Science and Technology; Clear Water Bay Kowloon, Hong Kong SAR
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28
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Sauguet L, Raia P, Henneke G, Delarue M. Shared active site architecture between archaeal PolD and multi-subunit RNA polymerases revealed by X-ray crystallography. Nat Commun 2016; 7:12227. [PMID: 27548043 PMCID: PMC4996933 DOI: 10.1038/ncomms12227] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Accepted: 06/10/2016] [Indexed: 02/06/2023] Open
Abstract
Archaeal replicative DNA polymerase D (PolD) constitute an atypical class of DNA polymerases made of a proofreading exonuclease subunit (DP1) and a larger polymerase catalytic subunit (DP2), both with unknown structures. We have determined the crystal structures of Pyrococcus abyssi DP1 and DP2 at 2.5 and 2.2 Å resolution, respectively, revealing a catalytic core strikingly different from all other known DNA polymerases (DNAPs). Rather, the PolD DP2 catalytic core has the same ‘double-psi β-barrel' architecture seen in the RNA polymerase (RNAP) superfamily, which includes multi-subunit transcriptases of all domains of life, homodimeric RNA-silencing pathway RNAPs and atypical viral RNAPs. This finding bridges together, in non-viral world, DNA transcription and DNA replication within the same protein superfamily. This study documents further the complex evolutionary history of the DNA replication apparatus in different domains of life and proposes a classification of all extant DNAPs. The structures of many DNA polymerases is known, but PolD was a missing piece. Here, the authors report the crystal structure of this protein and use it to connect the DNA replication machinery with the transcription machinery in the same protein family.
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Affiliation(s)
- Ludovic Sauguet
- Unit of Structural Dynamics of Macromolecules, Pasteur Institute and CNRS UMR 3528, 75015 Paris, France
| | - Pierre Raia
- Unit of Structural Dynamics of Macromolecules, Pasteur Institute and CNRS UMR 3528, 75015 Paris, France.,Pierre and Marie Curie University, Paris 6, 75006 Paris, France
| | - Ghislaine Henneke
- Ifremer, UMR 6197, Laboratoire de Microbiologie des Environnements Extrêmes, 29280 Plouzané, France.,UBO, UMR 6197, Laboratoire de Microbiologie des Environnements Extrêmes, 29280 Plouzané, France.,CNRS, UMR 6197, Laboratoire de Microbiologie des Environnements Extrêmes, 29280 Plouzané, France
| | - Marc Delarue
- Unit of Structural Dynamics of Macromolecules, Pasteur Institute and CNRS UMR 3528, 75015 Paris, France
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29
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Abstract
In some families there is an increased risk for colorectal cancer, caused by heritable, but often unidentified genetic mutations predisposing to the disease. We have identified the likely genetic cause for disease predisposition in a large family with high burden of colorectal adenomas and carcinomas, in addition to extra-colonic cancers. This family had previously been tested for known cancer susceptibility genes, with negative results. Exome sequencing was used to identify a novel mutation, c.1373A>T (p.Tyr458Phe), in the gene for DNA polymerase epsilon catalytic subunit (POLE). This mutation is located in the active site of the exonuclease domain of the enzyme, and affects a residue that has previously been shown to be important for exonuclease activity. The first predisposing mutation identified in POLE (c.1270C>G, p.Leu424Val) was associated with colorectal cancer only, but another mutation with a broader tumour spectrum (c.1089C>A, p.Asn363Lys) has recently been reported. In the family described in the present study, carriers generally have multiple colorectal adenomas and cancer of colon, pancreas, ovaries and small intestine which represents an important broadening of the tumour spectrum of POLE mutation carriers. We also observe a large phenotypic variation among the POLE mutation carriers in this family, most likely explained by modifying variants in other genes. One POLE mutation carrier has a novel variant in EXO1 (c.458C>T, p.Ala153Val), which may contribute to a more severe phenotype. The findings in this study will have important implications for risk assessment and surveillance of POLE mutation carriers.
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30
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Kel'in AV, Zlatev I, Harp J, Jayaraman M, Bisbe A, O'Shea J, Taneja N, Manoharan RM, Khan S, Charisse K, Maier MA, Egli M, Rajeev KG, Manoharan M. Structural Basis of Duplex Thermodynamic Stability and Enhanced Nuclease Resistance of 5'-C-Methyl Pyrimidine-Modified Oligonucleotides. J Org Chem 2016; 81:2261-79. [PMID: 26940174 DOI: 10.1021/acs.joc.5b02375] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Although judicious use of chemical modifications has contributed to the success of nucleic acid therapeutics, poor systemic stability remains a major hurdle. The introduction of functional groups around the phosphate backbone can enhance the nuclease resistance of oligonucleotides (ONs). Here, we report the synthesis of enantiomerically pure (R)- and (S)-5'-C-methyl (C5'-Me) substituted nucleosides and their incorporation into ONs. These modifications generally resulted in a decrease in thermal stability of oligonucleotide (ON) duplexes in a manner dependent on the stereoconfiguration at C5' with greater destabilization characteristic of (R)-epimers. Enhanced stability against snake venom phosphodiesterase resulted from modification of the 3'-end of an ON with either (R)- or (S)-C5'-Me nucleotides. The (S)-isomers with different 2'-substituents provided greater resistance against 3'-exonucleases than the corresponding (R)-isomers. Crystal structure analyses of RNA octamers with (R)- or (S)-5'-C-methyl-2'-deoxy-2'-fluorouridine [(R)- or (S)-C5'-Me-2'-FU, respectively] revealed that the stereochemical orientation of the C5'-Me and the steric effects that emanate from the alkyl substitution are the dominant determinants of thermal stability and are likely molecular origins of resistance against nucleases. X-ray and NMR structural analyses showed that the (S)-C5'-Me epimers are spatially and structurally more similar to their natural 5' nonmethylated counterparts than the corresponding (R)-epimers.
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Affiliation(s)
- Alexander V Kel'in
- Alnylam Pharmaceuticals , 300 Third Street, Cambridge, Massachusetts 02142, United States
| | - Ivan Zlatev
- Alnylam Pharmaceuticals , 300 Third Street, Cambridge, Massachusetts 02142, United States
| | - Joel Harp
- Department of Biochemistry and Center for Structural Biology, Vanderbilt University, School of Medicine , Nashville, Tennessee 37232, United States
| | - Muthusamy Jayaraman
- Alnylam Pharmaceuticals , 300 Third Street, Cambridge, Massachusetts 02142, United States
| | - Anna Bisbe
- Alnylam Pharmaceuticals , 300 Third Street, Cambridge, Massachusetts 02142, United States
| | - Jonathan O'Shea
- Alnylam Pharmaceuticals , 300 Third Street, Cambridge, Massachusetts 02142, United States
| | - Nate Taneja
- Alnylam Pharmaceuticals , 300 Third Street, Cambridge, Massachusetts 02142, United States
| | - Rajar M Manoharan
- Alnylam Pharmaceuticals , 300 Third Street, Cambridge, Massachusetts 02142, United States
| | - Saeed Khan
- Department of Chemistry and Biochemistry, University of California , Los Angeles, California 90095, United States
| | - Klaus Charisse
- Alnylam Pharmaceuticals , 300 Third Street, Cambridge, Massachusetts 02142, United States
| | - Martin A Maier
- Alnylam Pharmaceuticals , 300 Third Street, Cambridge, Massachusetts 02142, United States
| | - Martin Egli
- Department of Biochemistry and Center for Structural Biology, Vanderbilt University, School of Medicine , Nashville, Tennessee 37232, United States
| | | | - Muthiah Manoharan
- Alnylam Pharmaceuticals , 300 Third Street, Cambridge, Massachusetts 02142, United States
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31
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Palermo G, Cavalli A, Klein ML, Alfonso-Prieto M, Dal Peraro M, De Vivo M. Catalytic metal ions and enzymatic processing of DNA and RNA. Acc Chem Res 2015; 48:220-8. [PMID: 25590654 DOI: 10.1021/ar500314j] [Citation(s) in RCA: 117] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
CONSPECTUS: Two-metal-ion-dependent nucleases cleave the phosphodiester bonds of nucleic acids via the two-metal-ion (2M) mechanism. Several high-resolution X-ray structures portraying the two-metal-aided catalytic site, together with mutagenesis and kinetics studies, have demonstrated a functional role of the ions for catalysis in numerous metallonucleases. Overall, the experimental data confirm the general mechanistic hypothesis for 2M-aided phosphoryl transfer originally reported by Steitz and Steitz ( Proc. Natl. Acad. Sci. U.S.A. 1993 , 90 ( 14 ), 6498 - 6502 ). This seminal paper proposed that one metal ion favors the formation of the nucleophile, while the nearby second metal ion facilitates leaving group departure during RNA hydrolysis. Both metals were suggested to stabilize the enzymatic transition state. Nevertheless, static X-ray structures alone cannot exhaustively unravel how the two ions execute their functional role along the enzymatic reaction during processing of DNA or RNA strands when moving from reactants to products, passing through metastable intermediates and high-energy transition states. In this Account, we discuss the role of multiscale molecular simulations in further disclosing mechanistic insights of 2M-aided catalysis for two prototypical enzymatic targets for drug discovery, namely, ribonuclease H (RNase H) and type II topoisomerase (topoII). In both examples, first-principles molecular simulations, integrated with structural data, emphasize a cooperative motion of the bimetal motif during catalysis. The coordinated motion of both ions is crucial for maintaining a flexible metal-centered structural architecture exquisitely tailored to accommodate the DNA or RNA sugar-phosphate backbone during phosphodiester bond cleavage. Furthermore, our analysis of RNase H and the N-terminal domain (PAN) of influenza polymerase shows that classical molecular dynamics simulations coupled with enhanced sampling techniques have contributed to describe the modulatory effect of metal ion concentration and metal uptake on the 2M mechanism and efficiency. These aspects all point to the emerging and intriguing role of additional adjacent ions potentially involved in the modulation of phosphoryl transfer reactions and enzymatic turnover in 2M-catalysis, as recently observed experimentally in polymerase η and homing endonuclease I-DmoI. These computational results, integrated with experimental findings, describe and reinforce the nascent concept of a functional and cooperative dynamics of the catalytic metal ions during the 2M-dependent enzymatic processing of DNA and RNA. Encouraged by the insights provided by computational approaches, we foresee further experiments that will feature the functional and joint dynamics of the catalytic metal ions for nucleic acid processing. This could impact the de novo design of artificial metallonucleases and the rational design of potent metal-chelating inhibitors of pharmaceutically relevant enzymes.
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Affiliation(s)
- Giulia Palermo
- Department
of Drug Discovery and Development, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genoa, Italy
| | - Andrea Cavalli
- Department
of Drug Discovery and Development, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genoa, Italy
- Department
of Pharmacy and Biotechnology, University of Bologna, Via Belmeloro
6, I-40126 Bologna, Italy
| | - Michael L. Klein
- Institute
for Computational Molecular Science, Temple University, SERC Building, 1925 North 12th Street, Philadelphia Pennsylvania 19122, United States
| | - Mercedes Alfonso-Prieto
- Institute
for Computational Molecular Science, Temple University, SERC Building, 1925 North 12th Street, Philadelphia Pennsylvania 19122, United States
| | - Matteo Dal Peraro
- Institute
of Bioengineering, School of Life Sciences, École Polytechnique Fédérale de Lausanne - EPFL, 1015 Lausanne, Switzerland
- Swiss Institute of Bioinformatics - SIB, 1015 Lausanne, Switzerland
| | - Marco De Vivo
- Department
of Drug Discovery and Development, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genoa, Italy
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Eckstein F. Phosphorothioates, Essential Components of Therapeutic Oligonucleotides. Nucleic Acid Ther 2014; 24:374-87. [DOI: 10.1089/nat.2014.0506] [Citation(s) in RCA: 335] [Impact Index Per Article: 33.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Affiliation(s)
- Fritz Eckstein
- Max-Planck-Institut für Experimentelle Medizin, Göttingen, Germany
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Rosta E, Yang W, Hummer G. Calcium inhibition of ribonuclease H1 two-metal ion catalysis. J Am Chem Soc 2014; 136:3137-44. [PMID: 24499076 PMCID: PMC3985467 DOI: 10.1021/ja411408x] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2013] [Indexed: 01/05/2023]
Abstract
Most phosphate-processing enzymes require Mg(2+) as a cofactor to catalyze nucleotide cleavage and transfer reactions. Ca(2+) ions inhibit many of these enzymatic activities, despite Ca(2+) and Mg(2+) having comparable binding affinities and overall biological abundances. Here we study the molecular details of the calcium inhibition mechanism for phosphodiester cleavage, an essential reaction in the metabolism of nucleic acids and nucleotides, by comparing Ca(2+)- and Mg(2+) catalyzed reactions. We study the functional roles of the specific metal ion sites A and B in enabling the catalytic cleavage of an RNA/DNA hybrid substrate by B. halodurans ribonuclease (RNase) H1 using hybrid quantum-mechanics/molecular mechanics (QM/MM) free energy calculations. We find that Ca(2+) substitution of either of the two active-site Mg(2+) ions substantially increases the height of the reaction barrier and thereby abolishes the catalytic activity. Remarkably, Ca(2+) at the A site is inactive also in Mg(2+)-optimized active-site structures along the reaction path, whereas Mg(2+) substitution recovers activity in Ca(2+)-optimized structures. Geometric changes resulting from Ca(2+) substitution at metal ion site A may thus be a secondary factor in the loss of catalytic activity. By contrast, at metal ion site B geometry plays a more important role, with only a partial recovery of activity after Mg(2+) substitution in Ca(2+)-optimized structures. Ca(2+)-substitution also leads to a change in mechanism, with deprotonation of the water nucleophile requiring a closer approach to the scissile phosphate, which in turn increases the barrier. As a result, Ca(2+) is less efficient in activating the water. As a likely cause for the different reactivities of Mg(2+) and Ca(2+) ions in site A, we identify differences in charge transfer to the ions and the associated decrease in the pKa of the oxygen nucleophile attacking the phosphate group.
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Affiliation(s)
- Edina Rosta
- Laboratory
of Chemical Physics, National Institute of
Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892-0520, United States
- Department
of Chemistry, King’s College London, London SE1 1DB, United Kingdom
| | - Wei Yang
- Laboratory
of Molecular Biology, National Institute
of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, United States
| | - Gerhard Hummer
- Laboratory
of Chemical Physics, National Institute of
Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892-0520, United States
- Department
of Theoretical Biophysics, Max Planck Institute
of Biophysics, 60438 Frankfurt am Main, Germany
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Kaur M, Rob A, Caton-Williams J, Huang Z. Biochemistry of Nucleic Acids Functionalized with Sulfur, Selenium, and Tellurium: Roles of the Single-Atom Substitution. ACTA ACUST UNITED AC 2013. [DOI: 10.1021/bk-2013-1152.ch005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/07/2023]
Affiliation(s)
- Manindar Kaur
- Department of Chemistry, Georgia State University, Atlanta, Georgia 30303
| | - Abdur Rob
- Department of Chemistry, Georgia State University, Atlanta, Georgia 30303
| | | | - Zhen Huang
- Department of Chemistry, Georgia State University, Atlanta, Georgia 30303
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35
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Wang T, Sun HL, Cheng F, Zhang XE, Bi L, Jiang T. Recognition and processing of double-stranded DNA by ExoX, a distributive 3'-5' exonuclease. Nucleic Acids Res 2013; 41:7556-65. [PMID: 23771145 PMCID: PMC3753628 DOI: 10.1093/nar/gkt495] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Members of the DnaQ superfamily are major 3'-5' exonucleases that degrade either only single-stranded DNA (ssDNA) or both ssDNA and double-stranded DNA (dsDNA). However, the mechanism by which dsDNA is recognized and digested remains unclear. Exonuclease X (ExoX) is a distributive DnaQ exonuclease that cleaves both ssDNA and dsDNA substrates. Here, we report the crystal structures of Escherichia coli ExoX in complex with three different dsDNA substrates: 3' overhanging dsDNA, blunt-ended dsDNA and 3' recessed mismatch-containing dsDNA. In these structures, ExoX binds to dsDNA via both a conserved substrate strand-interacting site and a previously uncharacterized complementary strand-interacting motif. When ExoX complexes with blunt-ended dsDNA or 5' overhanging dsDNA, a 'wedge' composed of Leu12 and Gln13 penetrates between the first two base pairs to break the 3' terminal base pair and facilitates precise feeding of the 3' terminus of the substrate strand into the ExoX cleavage active site. Site-directed mutagenesis showed that the complementary strand-binding site and the wedge of ExoX are dsDNA specific. Together with the results of structural comparisons, our data support a mechanism by which normal and mismatched dsDNA are recognized and digested by E. coli ExoX. The crystal structures also provide insight into the structural framework of the different substrate specificities of the DnaQ family members.
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Affiliation(s)
- Tianyu Wang
- National Key Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Chaoyang District, Beijing 100101, China, Graduate School of Chinese Academy of Sciences, Beijing 100039, China and State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, China
| | - Han-Li Sun
- National Key Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Chaoyang District, Beijing 100101, China, Graduate School of Chinese Academy of Sciences, Beijing 100039, China and State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, China
| | - Fang Cheng
- National Key Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Chaoyang District, Beijing 100101, China, Graduate School of Chinese Academy of Sciences, Beijing 100039, China and State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, China
| | - Xian-En Zhang
- National Key Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Chaoyang District, Beijing 100101, China, Graduate School of Chinese Academy of Sciences, Beijing 100039, China and State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, China
| | - Lijun Bi
- National Key Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Chaoyang District, Beijing 100101, China, Graduate School of Chinese Academy of Sciences, Beijing 100039, China and State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, China,*To whom correspondence should be addressed. Tel/Fax: +86 10 64888510;
| | - Tao Jiang
- National Key Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Chaoyang District, Beijing 100101, China, Graduate School of Chinese Academy of Sciences, Beijing 100039, China and State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, China,*To whom correspondence should be addressed. Tel/Fax: +86 10 64888510;
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36
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Virtanen A, Henriksson N, Nilsson P, Nissbeck M. Poly(A)-specific ribonuclease (PARN): an allosterically regulated, processive and mRNA cap-interacting deadenylase. Crit Rev Biochem Mol Biol 2013; 48:192-209. [PMID: 23496118 DOI: 10.3109/10409238.2013.771132] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Deadenylation of eukaryotic mRNA is a mechanism critical for mRNA function by influencing mRNA turnover and efficiency of protein synthesis. Here, we review poly(A)-specific ribonuclease (PARN), which is one of the biochemically best characterized deadenylases. PARN is unique among the currently known eukaryotic poly(A) degrading nucleases, being the only deadenylase that has the capacity to directly interact during poly(A) hydrolysis with both the m(7)G-cap structure and the poly(A) tail of the mRNA. In short, PARN is a divalent metal-ion dependent poly(A)-specific, processive and cap-interacting 3'-5' exoribonuclease that efficiently degrades poly(A) tails of eukaryotic mRNAs. We discuss in detail the mechanisms of its substrate recognition, catalysis, allostery and processive mode of action. On the basis of biochemical and structural evidence, we present and discuss a working model for PARN action. Models of regulation of PARN activity by trans-acting factors are discussed as well as the physiological relevance of PARN.
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Affiliation(s)
- Anders Virtanen
- Department of Cell and Molecular Biology, Program of Chemical Biology, Uppsala University, Uppsala, Sweden.
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37
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Terrazas M, Alagia A, Faustino I, Orozco M, Eritja R. Functionalization of the 3'-ends of DNA and RNA strands with N-ethyl-N-coupled nucleosides: a promising approach to avoid 3'-exonuclease-catalyzed hydrolysis of therapeutic oligonucleotides. Chembiochem 2013; 14:510-20. [PMID: 23362010 DOI: 10.1002/cbic.201200611] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2012] [Indexed: 01/29/2023]
Abstract
The development of nucleic acid derivatives to generate novel medical treatments has become increasingly popular, but the high vulnerability of oligonucleotides to nucleases limits their practical use. We explored the possibility of increasing the stability against 3'-exonucleases by replacing the two 3'-terminal nucleotides by N-ethyl-N-coupled nucleosides. Molecular dynamics simulations of 3'-N-ethyl-N-modified DNA:Klenow fragment complexes suggested that this kind of alteration has negative effects on the correct positioning of the adjacent scissile phosphodiester bond at the active site of the enzyme, and accordingly was expected to protect the oligonucleotide from degradation. We verified that these modifications conferred complete resistance to 3'-exonucleases. Furthermore, cellular RNAi experiments with 3'-N-ethyl-N-modified siRNAs showed that these modifications were compatible with the RNAi machinery. Overall, our experimental and theoretical studies strongly suggest that these modified oligonucleotides could be valuable for therapeutic applications.
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Affiliation(s)
- Montserrat Terrazas
- Institute for Research in Biomedicine (IRB Barcelona) and Institute for Advanced Chemistry of Catalonia (IQAC), Spanish Research Council (CSIC), Cluster Building, Baldiri i Reixac 10, 08028 Barcelona, Spain.
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38
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Shanahan CA, Gaffney BL, Jones RA, Strobel SA. Identification of c-di-GMP derivatives resistant to an EAL domain phosphodiesterase. Biochemistry 2013; 52:365-77. [PMID: 23256840 DOI: 10.1021/bi301510v] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The bacterial second messenger signaling molecule bis-(3'-5')-cyclic dimeric guanosine monophosphate (c-di-GMP) controls important biological processes such as biofilm formation, virulence response, and motility. This second messenger is sensed by macromolecular targets inside the cell, both protein and RNA, which induce specific phenotypic responses critical for bacterial survival. One class of enzymes responsible for regulating the intracellular concentration of c-di-GMP, and therefore the physiological behavior of the cell, consists of the EAL domain phosphodiesterases, which degrade the second messenger to its linear form, pGpG. Here, we investigate how base and backbone modifications of c-di-GMP affect the rate of cyclic dinucleotide degradation by an EAL domain protein (CC3396 from Caulobacter crescentus). The doubly substituted thiophosphate analogue is highly resistant to hydrolysis by this metabolizing enzyme but can still bind c-di-GMP riboswitch targets. We used these findings to develop a novel ribosyl phosphate-modified derivative of c-di-GMP containing 2'-deoxy and methylphosphonate substitutions that is charge neutral and demonstrate that this analogue is also resistant to EAL domain-catalyzed degradation. This suggests a general strategy for designing c-di-GMP derivatives with increased enzymatic stability that also possess desirable properties for development as chemical probes of c-di-GMP signaling.
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Affiliation(s)
- Carly A Shanahan
- Department of Chemistry, Yale University , New Haven, Connecticut 06520, USA
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39
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Hare S, Maertens GN, Cherepanov P. 3'-processing and strand transfer catalysed by retroviral integrase in crystallo. EMBO J 2012; 31:3020-8. [PMID: 22580823 PMCID: PMC3395085 DOI: 10.1038/emboj.2012.118] [Citation(s) in RCA: 120] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2012] [Accepted: 04/02/2012] [Indexed: 12/19/2022] Open
Abstract
Structures of a prototype integrase bound to viral cDNA offer insights into the early steps of retroviral host genome integration, and into the mechanisms of action of viral DNA strand transfer inhibitor (INSTI) drugs. Retroviral integrase (IN) is responsible for two consecutive reactions, which lead to insertion of a viral DNA copy into a host cell chromosome. Initially, the enzyme removes di- or trinucleotides from viral DNA ends to expose 3′-hydroxyls attached to the invariant CA dinucleotides (3′-processing reaction). Second, it inserts the processed 3′-viral DNA ends into host chromosomal DNA (strand transfer). Herein, we report a crystal structure of prototype foamy virus IN bound to viral DNA prior to 3′-processing. Furthermore, taking advantage of its dependence on divalent metal ion cofactors, we were able to freeze trap the viral enzyme in its ground states containing all the components necessary for 3′-processing or strand transfer. Our results shed light on the mechanics of retroviral DNA integration and explain why HIV IN strand transfer inhibitors are ineffective against the 3′-processing step of integration. The ground state structures moreover highlight a striking substrate mimicry utilized by the inhibitors in their binding to the IN active site and suggest ways to improve upon this clinically relevant class of small molecules.
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Affiliation(s)
- Stephen Hare
- Division of Infectious Diseases, Imperial College London, London, UK
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40
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Hare S, Maertens GN, Cherepanov P. 3'-processing and strand transfer catalysed by retroviral integrase in crystallo. EMBO J 2012. [PMID: 22580823 DOI: 10.1038/emboj.2012.118emboj2012118] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Retroviral integrase (IN) is responsible for two consecutive reactions, which lead to insertion of a viral DNA copy into a host cell chromosome. Initially, the enzyme removes di- or trinucleotides from viral DNA ends to expose 3'-hydroxyls attached to the invariant CA dinucleotides (3'-processing reaction). Second, it inserts the processed 3'-viral DNA ends into host chromosomal DNA (strand transfer). Herein, we report a crystal structure of prototype foamy virus IN bound to viral DNA prior to 3'-processing. Furthermore, taking advantage of its dependence on divalent metal ion cofactors, we were able to freeze trap the viral enzyme in its ground states containing all the components necessary for 3'-processing or strand transfer. Our results shed light on the mechanics of retroviral DNA integration and explain why HIV IN strand transfer inhibitors are ineffective against the 3'-processing step of integration. The ground state structures moreover highlight a striking substrate mimicry utilized by the inhibitors in their binding to the IN active site and suggest ways to improve upon this clinically relevant class of small molecules.
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Affiliation(s)
- Stephen Hare
- Division of Infectious Diseases, Imperial College London, London, UK
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41
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Schwartz A, Rabhi M, Margeat E, Boudvillain M. Analysis of helicase-RNA interactions using nucleotide analog interference mapping. Methods Enzymol 2012; 511:149-69. [PMID: 22713319 DOI: 10.1016/b978-0-12-396546-2.00007-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Nucleotide analog interference mapping (NAIM) is a combinatorial approach that probes individual atoms and functional groups in an RNA molecule and identifies those that are important for a specific biochemical function. Here, we show how NAIM can be adapted to reveal functionally important atoms and groups on RNA substrates of helicases. We explain how NAIM can be used to investigate translocation and unwinding mechanisms of helicases and discuss the advantages and limitations of this powerful chemogenetic approach.
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Affiliation(s)
- Annie Schwartz
- CNRS UPR4301, Centre de Biophysique Moléculaire, Orléans cedex 2, France
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42
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Sigel A, Operschall BP, Sigel H. Steric guiding of metal ion binding to a purine residue by a non-coordinating amino group: Examplified by 9-[(2-phosphonomethoxy)ethyl]-2-aminopurine (PME2AP), an isomer of the antiviral nucleotide analogue 9-[(2-phosphonomethoxy)ethyl]adenine (PMEA), and by related compounds. Coord Chem Rev 2012. [DOI: 10.1016/j.ccr.2011.06.030] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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43
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Sano S, Yamada Y, Shinkawa T, Kato S, Okada T, Higashibata H, Fujiwara S. Mutations to create thermostable reverse transcriptase with bacterial family A DNA polymerase from Thermotoga petrophila K4. J Biosci Bioeng 2011; 113:315-21. [PMID: 22143068 DOI: 10.1016/j.jbiosc.2011.11.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2011] [Revised: 10/31/2011] [Accepted: 11/01/2011] [Indexed: 11/28/2022]
Abstract
Family A DNA polymerase (K4PolI) from Thermotoga petrophila K4 was obtained as a recombinant form, and the enzyme characteristics were analyzed. K4PolI showed thermostable DNA-dependent DNA polymerase activity with 3'-5' exonuclease activity but no detectable RNA-dependent DNA polymerase activity. Its tertiary structure was speculated by in silico modeling to understand the binding situation between K4PolI and template DNA. Nine amino acids in the 3'-5' exonuclease domain are predicted to be involved in DNA/RNA distinction by steric interference with the 2' hydroxy group of ribose. To allow K4PolI to accept RNA as the template, mutants were constructed focusing on the amino acids located around the 2' hydroxyl group of the bound ribose. The mutants in which Thr326, Leu329, Gln384, Phe388, Met408, or Tyr438 was replaced with Ala (designated as T326A, L329A, Q384A, F388A, M408A, or Y438A, respectively) showed RNA-dependent DNA polymerase activity. All the mutants showed reduced 3'-5' exonuclease activity, suggesting that gain of reverse transcriptase activity is correlated with loss of 3'-5' exonuclease activity. In particular, the mutants enabled direct DNA amplification in a single tube format from structured RNA that was not efficiently amplified by retroviral reverse transcriptase.
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Affiliation(s)
- Sotaro Sano
- Department of Bioscience, Graduate School of Science and Technology, Kwansei-Gakuin University, 2-1 Gakuen, Sanda, Hyogo 669-1337, Japan
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44
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Voorhees RM, Schmeing TM, Kelley AC, Ramakrishnan V. Response to Comment on "The Mechanism for Activation of GTP Hydrolysis on the Ribosome". Science 2011; 333:37; author reply 37. [DOI: 10.1126/science.1202532] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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45
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Orans J, McSweeney EA, Iyer RR, Hast MA, Hellinga HW, Modrich P, Beese LS. Structures of human exonuclease 1 DNA complexes suggest a unified mechanism for nuclease family. Cell 2011; 145:212-23. [PMID: 21496642 DOI: 10.1016/j.cell.2011.03.005] [Citation(s) in RCA: 125] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2010] [Revised: 01/25/2011] [Accepted: 03/01/2011] [Indexed: 11/16/2022]
Abstract
Human exonuclease 1 (hExo1) plays important roles in DNA repair and recombination processes that maintain genomic integrity. It is a member of the 5' structure-specific nuclease family of exonucleases and endonucleases that includes FEN-1, XPG, and GEN1. We present structures of hExo1 in complex with a DNA substrate, followed by mutagenesis studies, and propose a common mechanism by which this nuclease family recognizes and processes diverse DNA structures. hExo1 induces a sharp bend in the DNA at nicks or gaps. Frayed 5' ends of nicked duplexes resemble flap junctions, unifying the mechanisms of endo- and exonucleolytic processing. Conformational control of a mobile region in the catalytic site suggests a mechanism for allosteric regulation by binding to protein partners. The relative arrangement of substrate binding sites in these enzymes provides an elegant solution to a complex geometrical puzzle of substrate recognition and processing.
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Affiliation(s)
- Jillian Orans
- Department of Biochemistry, Duke University Medical Center, Durham, NC 27710, USA
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46
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Abstract
Nucleases cleave the phosphodiester bonds of nucleic acids and may be endo or exo, DNase or RNase, topoisomerases, recombinases, ribozymes, or RNA splicing enzymes. In this review, I survey nuclease activities with known structures and catalytic machinery and classify them by reaction mechanism and metal-ion dependence and by their biological function ranging from DNA replication, recombination, repair, RNA maturation, processing, interference, to defense, nutrient regeneration or cell death. Several general principles emerge from this analysis. There is little correlation between catalytic mechanism and biological function. A single catalytic mechanism can be adapted in a variety of reactions and biological pathways. Conversely, a single biological process can often be accomplished by multiple tertiary and quaternary folds and by more than one catalytic mechanism. Two-metal-ion-dependent nucleases comprise the largest number of different tertiary folds and mediate the most diverse set of biological functions. Metal-ion-dependent cleavage is exclusively associated with exonucleases producing mononucleotides and endonucleases that cleave double- or single-stranded substrates in helical and base-stacked conformations. All metal-ion-independent RNases generate 2',3'-cyclic phosphate products, and all metal-ion-independent DNases form phospho-protein intermediates. I also find several previously unnoted relationships between different nucleases and shared catalytic configurations.
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47
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A nuclear family A DNA polymerase from Entamoeba histolytica bypasses thymine glycol. PLoS Negl Trop Dis 2010; 4:e786. [PMID: 20706627 PMCID: PMC2919377 DOI: 10.1371/journal.pntd.0000786] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2010] [Accepted: 07/12/2010] [Indexed: 01/26/2023] Open
Abstract
Background Eukaryotic family A DNA polymerases are involved in mitochondrial DNA replication or translesion DNA synthesis. Here, we present evidence that the sole family A DNA polymerase from the parasite protozoan E. histolytica (EhDNApolA) localizes to the nucleus and that its biochemical properties indicate that this DNA polymerase may be involved in translesion DNA synthesis. Methodology and Results EhDNApolA is the sole family A DNA polymerase in E. histolytica. An in silico analysis places family A DNA polymerases from the genus Entamoeba in a separate branch of a family A DNA polymerases phylogenetic tree. Biochemical studies of a purified recombinant EhDNApolA demonstrated that this polymerase is active in primer elongation, is poorly processive, displays moderate strand displacement, and does not contain 3′–5′ exonuclease or editing activity. Importantly, EhDNApolA bypasses thymine glycol lesions with high fidelity, and confocal microscopy demonstrates that this polymerase is translocated into the nucleus. These data suggest a putative role of EhDNApolA in translesion DNA synthesis in E. histolytica. Conclusion This is the first report of the biochemical characterization of a DNA polymerase from E. histolytica. EhDNApolA is a family A DNA polymerase that is grouped into a new subfamily of DNA polymerases with translesion DNA synthesis capabilities similar to DNA polymerases from subfamily ν. Genotoxic agents like ultraviolet radiation, alkylating compounds and reactive oxidative species have the potential to originate DNA lesions that are not bypassed by replicative DNA polymerases. Eukaryotic organisms contain a specialized subset of DNA polymerases capable of translesion DNA synthesis. These DNA polymerases belong to DNA polymerases from families A, B, and Y. In this work, we characterized the sole family A DNA polymerase of the parasitic protozoa E. histolytica, EhDNApolA. The biochemical characterization of recombinant EhDNApolA indicates that this protein is an active DNA polymerase able to primer extension and moderate strand displacement. The ability of EhDNApolA to faithfully incorporate dATP opposite thymine glycol, and its nuclear localization indicates that this polymerase may have a role in translesion DNA synthesis. E. histolytica is exposed to oxidative stress during tissue invasion by phagocytes. Understanding DNA metabolism in E. histolytica is important because this parasite has shaped some metabolic pathways by horizontal gene transfer, infects approximately 50 million people annually, and is the second leading cause of death among protozoan diseases.
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Wojcik M, Stec WJ. The effect of divalent cations on the catalytic activity of the human plasma 3'-exonuclease. Biometals 2010; 23:1113-21. [PMID: 20589414 DOI: 10.1007/s10534-010-9358-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2009] [Accepted: 06/12/2010] [Indexed: 11/26/2022]
Abstract
The 3'-exonuclease from human plasma is a soluble form of nucleotide pyrophosphatase/phosphodiesterase 1 (NPP1) (EC 3.1.4.1/EC 3.6.1.9). Here, the possibility of divalent cation influence for the 3'-exonuclease activity was investigated using the phosphorothioate congener of oligonucleotide containing all phosphorothioate internucleotide linkages of the [R(P)]-configuration ([R(P)-PS]-d[T(12)]) as the substrate for this enzyme. It was found that the 3'-exonuclease is a metalloenzyme, i.e. its phosphodiesterase activity was completely abolished at 0.8 mM concentration EDTA and, in turn, it was restored in the presence of Mg(2+) or Mn(2+) ions. In addition, Mg(2+) can be replaced effectively by Ca(2+), Mn(2+), or Co(2+), but not by Ni(2+) and Cd(2+) during the hydrolysis of the phosphorothioate substrate in human plasma. In addition, the mechanism is postulated, by which a single internucleotide phosphorothioate bond of the S(P)-configuration at the 3'-end of unmodified phosphodiesters (PO-oligos), or their phosporothioate analogs (PS-oligos) protects these compounds against degradation in blood.
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Affiliation(s)
- Marzena Wojcik
- Department of Structural Biology, Medical University of Łódź, 7/9 Żeligowskiego St, 90-752, Lodz, Poland.
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Abstract
Type II topoisomerases are essential enzymes that regulate DNA under- and overwinding and remove knots and tangles from the genetic material. In order to carry out their critical physiological functions, these enzymes utilize a double-stranded DNA passage mechanism that requires them to generate a transient double-stranded break. Consequently, while necessary for cell survival, type II topoisomerases also have the capacity to fragment the genome. This feature of the prokaryotic and eukaryotic enzymes, respectively, is exploited to treat a variety of bacterial infections and cancers in humans. All type II topoisomerases require divalent metal ions for catalytic function. These metal ions function in two separate active sites and are necessary for the ATPase and DNA cleavage/ligation activities of the enzymes. ATPase activity is required for the strand passage process and utilizes the metal-dependent binding and hydrolysis of ATP to drive structural rearrangements in the protein. Both the DNA cleavage and ligation activities of type II topoisomerases require divalent metal ions and appear to utilize a novel variant of the canonical two-metal-ion phosphotransferase/hydrolase mechanism to facilitate these reactions. This article will focus primarily on eukaryotic type II topoisomerases and the roles of metal ions in the catalytic functions of these enzymes.
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Affiliation(s)
- Joseph E Deweese
- Department of Pharmaceutical Sciences, Lipscomb University College of Pharmacy, Nashville, TN 37204-3951, USA
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Santoso Y, Kapanidis AN. Probing biomolecular structures and dynamics of single molecules using in-gel alternating-laser excitation. Anal Chem 2010; 81:9561-70. [PMID: 19863108 DOI: 10.1021/ac901423e] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Gel electrophoresis is a standard biochemical technique used for separating biomolecules on the basis of size and charge. Despite the use of gels in early single-molecule experiments, gel electrophoresis has not been widely adopted for single-molecule fluorescence spectroscopy. We present a novel method that combines gel electrophoresis and single-molecule fluorescence spectroscopy to simultaneously purify and analyze biomolecules in a gel matrix. Our method, in-gel alternating-laser excitation (ALEX), uses nondenaturing gels to purify biomolecular complexes of interest from free components, aggregates, and nonspecific complexes. The gel matrix also slows down translational diffusion of molecules, giving rise to long, high-resolution time traces without surface immobilization, which allow extended observations of conformational dynamics in a biologically friendly environment. We demonstrated the compatibility of this method with different types of single molecule spectroscopy techniques, including confocal detection and fluorescence-correlation spectroscopy. We demonstrated that in-gel ALEX can be used to study conformational dynamics at the millisecond time scale; by studying a DNA hairpin in gels, we directly observed fluorescence fluctuations due to conformational interconversion between folded and unfolded states. Our method is amenable to the addition of small molecules that can alter the equilibrium and dynamic properties of the system. In-gel ALEX will be a versatile tool for studying structures and dynamics of complex biomolecules and their assemblies.
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Affiliation(s)
- Yusdi Santoso
- Department of Physics and Biological Physics Research Group, Clarendon Laboratory, University of Oxford, Parks Road, Oxford, OX1 3PU, United Kingdom.
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