1
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Chang C, Zhou G, Lee Luo C, Eleraky S, Moradi M, Gao Y. Sugar ring alignment and dynamics underline cytarabine and gemcitabine inhibition on Pol η catalyzed DNA synthesis. J Biol Chem 2024; 300:107361. [PMID: 38735473 PMCID: PMC11176770 DOI: 10.1016/j.jbc.2024.107361] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2023] [Revised: 05/02/2024] [Accepted: 05/03/2024] [Indexed: 05/14/2024] Open
Abstract
Nucleoside analogue drugs are pervasively used as antiviral and chemotherapy agents. Cytarabine and gemcitabine are anti-cancer nucleoside analogue drugs that contain C2' modifications on the sugar ring. Despite carrying all the required functional groups for DNA synthesis, these two compounds inhibit DNA extension once incorporated into DNA. It remains unclear how the C2' modifications on cytarabine and gemcitabine affect the polymerase active site during substrate binding and DNA extension. Using steady-state kinetics, static and time-resolved X-ray crystallography with DNA polymerase η (Pol η) as a model system, we showed that the sugar ring C2' chemical groups on cytarabine and gemcitabine snugly fit within the Pol η active site without occluding the steric gate. During DNA extension, Pol η can extend past gemcitabine but with much lower efficiency past cytarabine. The Pol η crystal structures show that the -OH modification in the β direction on cytarabine locks the sugar ring in an unfavorable C2'-endo geometry for product formation. On the other hand, the addition of fluorine atoms on gemcitabine alters the proper conformational transition of the sugar ring for DNA synthesis. Our study illustrates mechanistic insights into chemotherapeutic drug inhibition and resistance and guides future optimization of nucleoside analogue drugs.
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Affiliation(s)
- Caleb Chang
- Department of Biosciences, Rice University, Houston, Texas, USA
| | - Grace Zhou
- Department of Biosciences, Rice University, Houston, Texas, USA
| | | | - Sarah Eleraky
- Department of Biosciences, Rice University, Houston, Texas, USA
| | - Madeline Moradi
- Department of Biosciences, Rice University, Houston, Texas, USA
| | - Yang Gao
- Department of Biosciences, Rice University, Houston, Texas, USA.
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2
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Morales-Ruiz T, Beltrán-Melero C, Ortega-Paredes D, Luna-Morillo JA, Martínez-Macías MI, Roldán-Arjona T, Ariza RR, Córdoba-Cañero D. The enzymatic properties of Arabidopsis thaliana DNA polymerase λ suggest a role in base excision repair. PLANT MOLECULAR BIOLOGY 2024; 114:3. [PMID: 38217735 PMCID: PMC10787897 DOI: 10.1007/s11103-023-01407-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Accepted: 11/27/2023] [Indexed: 01/15/2024]
Abstract
Base excision repair (BER) generates gapped DNA intermediates containing a 5'-terminal 2-deoxyribose-5-phosphate (5'-dRP) group. In mammalian cells, gap filling and dRP removal are catalyzed by Pol β, which belongs to the X family of DNA polymerases. In higher plants, the only member of the X family of DNA polymerases is Pol λ. Although it is generally believed that plant Pol λ participates in BER, there is limited experimental evidence for this hypothesis. Here we have characterized the biochemical properties of Arabidopsis thaliana Pol λ (AtPol λ) in a BER context, using a variety of DNA repair intermediates. We have found that AtPol λ performs gap filling inserting the correct nucleotide, and that the rate of nucleotide incorporation is higher in substrates containing a C in the template strand. Gap filling catalyzed by AtPol λ is most efficient with a phosphate at the 5'-end of the gap and is not inhibited by the presence of a 5'-dRP mimic. We also show that AtPol λ possesses an intrinsic dRP lyase activity that is reduced by mutations at two lysine residues in its 8-kDa domain, one of which is present in Pol λ exclusively and not in any Pol β homolog. Importantly, we also found that the dRP lyase activity of AtPol λ allows efficient completion of uracil repair in a reconstituted short-patch BER reaction. These results suggest that AtPol λ plays an important role in plant BER.
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Affiliation(s)
- T Morales-Ruiz
- Department of Genetics, University of Córdoba, Córdoba, Spain
- Maimónides Biomedical Research Institute of Córdoba (IMIBIC), Córdoba, Spain
- Reina Sofía University Hospital, Córdoba, Spain
| | - C Beltrán-Melero
- Department of Genetics, University of Córdoba, Córdoba, Spain
- Maimónides Biomedical Research Institute of Córdoba (IMIBIC), Córdoba, Spain
- Reina Sofía University Hospital, Córdoba, Spain
| | - D Ortega-Paredes
- Department of Genetics, University of Córdoba, Córdoba, Spain
- Maimónides Biomedical Research Institute of Córdoba (IMIBIC), Córdoba, Spain
- Reina Sofía University Hospital, Córdoba, Spain
| | - J A Luna-Morillo
- Department of Genetics, University of Córdoba, Córdoba, Spain
- Maimónides Biomedical Research Institute of Córdoba (IMIBIC), Córdoba, Spain
- Reina Sofía University Hospital, Córdoba, Spain
| | - M I Martínez-Macías
- Department of Genetics, University of Córdoba, Córdoba, Spain
- Maimónides Biomedical Research Institute of Córdoba (IMIBIC), Córdoba, Spain
- Reina Sofía University Hospital, Córdoba, Spain
| | - T Roldán-Arjona
- Department of Genetics, University of Córdoba, Córdoba, Spain
- Maimónides Biomedical Research Institute of Córdoba (IMIBIC), Córdoba, Spain
- Reina Sofía University Hospital, Córdoba, Spain
| | - R R Ariza
- Department of Genetics, University of Córdoba, Córdoba, Spain
- Maimónides Biomedical Research Institute of Córdoba (IMIBIC), Córdoba, Spain
- Reina Sofía University Hospital, Córdoba, Spain
| | - D Córdoba-Cañero
- Department of Genetics, University of Córdoba, Córdoba, Spain.
- Maimónides Biomedical Research Institute of Córdoba (IMIBIC), Córdoba, Spain.
- Reina Sofía University Hospital, Córdoba, Spain.
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3
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Parkash V, Kulkarni Y, Bylund GO, Osterman P, Kamerlin S, Johansson E. A sensor complements the steric gate when DNA polymerase ϵ discriminates ribonucleotides. Nucleic Acids Res 2023; 51:11225-11238. [PMID: 37819038 PMCID: PMC10639073 DOI: 10.1093/nar/gkad817] [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: 07/01/2023] [Revised: 09/01/2023] [Accepted: 09/20/2023] [Indexed: 10/13/2023] Open
Abstract
The cellular imbalance between high concentrations of ribonucleotides (NTPs) and low concentrations of deoxyribonucleotides (dNTPs), is challenging for DNA polymerases when building DNA from dNTPs. It is currently believed that DNA polymerases discriminate against NTPs through a steric gate model involving a clash between a tyrosine and the 2'-hydroxyl of the ribonucleotide in the polymerase active site in B-family DNA polymerases. With the help of crystal structures of a B-family polymerase with a UTP or CTP in the active site, molecular dynamics simulations, biochemical assays and yeast genetics, we have identified a mechanism by which the finger domain of the polymerase sense NTPs in the polymerase active site. In contrast to the previously proposed polar filter, our experiments suggest that the amino acid residue in the finger domain senses ribonucleotides by steric hindrance. Furthermore, our results demonstrate that the steric gate in the palm domain and the sensor in the finger domain are both important when discriminating NTPs. Structural comparisons reveal that the sensor residue is conserved among B-family polymerases and we hypothesize that a sensor in the finger domain should be considered in all types of DNA polymerases.
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Affiliation(s)
- Vimal Parkash
- Department of Medical Biochemistry and Biophysics, Umeå University, Umeå 90187, Sweden
| | - Yashraj Kulkarni
- Department of Chemistry - BMC, Uppsala University, Box 576, Uppsala S-751 23, Sweden
- Department of Drug Design and Pharmacology, University of Copenhagen, Universitetsparken 2, 2100 Copenhagen, Denmark
| | - Göran O Bylund
- Department of Medical Biochemistry and Biophysics, Umeå University, Umeå 90187, Sweden
| | - Pia Osterman
- Department of Medical Biochemistry and Biophysics, Umeå University, Umeå 90187, Sweden
| | - Shina Caroline Lynn Kamerlin
- Department of Chemistry - BMC, Uppsala University, Box 576, Uppsala S-751 23, Sweden
- School of Chemistry and Biochemistry, Georgia Institute of Technology, 901 Atlantic Drive NW, Atlanta, GA 30332-0400, USA
| | - Erik Johansson
- Department of Medical Biochemistry and Biophysics, Umeå University, Umeå 90187, Sweden
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4
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Oscorbin I, Filipenko M. Bst polymerase - a humble relative of Taq polymerase. Comput Struct Biotechnol J 2023; 21:4519-4535. [PMID: 37767105 PMCID: PMC10520511 DOI: 10.1016/j.csbj.2023.09.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2023] [Revised: 08/31/2023] [Accepted: 09/10/2023] [Indexed: 09/29/2023] Open
Abstract
DNA polymerases are a superfamily of enzymes synthesizing DNA using DNA as a template. They are essential for nucleic acid metabolism and for DNA replication and repair. Modern biotechnology and molecular diagnostics rely heavily on DNA polymerases in analyzing nucleic acids. Among a variety of discovered DNA polymerases, Bst polymerase, a large fragment of DNA polymerase I from Geobacillus stearothermophilus, is one of the most commonly used but is not as well studied as Taq polymerase. The ability of Bst polymerase to displace an upstream DNA strand during synthesis, coupled with its moderate thermal stability, has provided the basis for several isothermal DNA amplification methods, including LAMP, WGA, RCA, and many others. Bst polymerase is one of the key components defining the robustness and analytical characteristics of diagnostic test systems based on isothermal amplification. Here, we present an overview of the biochemical and structural features of Bst polymerase and provide information on its mutated analogs.
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Affiliation(s)
- Igor Oscorbin
- Laboratory of Pharmacogenomics, Institute of Chemical Biology and Fundamental Medicine, Siberian Branch of the Russian Academy of Sciences (ICBFM SB RAS), 8 Lavrentiev Avenue, Novosibirsk 630090, Russia
| | - Maxim Filipenko
- Laboratory of Pharmacogenomics, Institute of Chemical Biology and Fundamental Medicine, Siberian Branch of the Russian Academy of Sciences (ICBFM SB RAS), 8 Lavrentiev Avenue, Novosibirsk 630090, Russia
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5
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Primer terminal ribonucleotide alters the active site dynamics of DNA polymerase η and reduces DNA synthesis fidelity. J Biol Chem 2023; 299:102938. [PMID: 36702254 PMCID: PMC9976465 DOI: 10.1016/j.jbc.2023.102938] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2022] [Revised: 01/19/2023] [Accepted: 01/20/2023] [Indexed: 01/25/2023] Open
Abstract
DNA polymerases catalyze DNA synthesis with high efficiency, which is essential for all life. Extensive kinetic and structural efforts have been executed in exploring mechanisms of DNA polymerases, surrounding their kinetic pathway, catalytic mechanisms, and factors that dictate polymerase fidelity. Recent time-resolved crystallography studies on DNA polymerase η (Pol η) and β have revealed essential transient events during the DNA synthesis reaction, such as mechanisms of primer deprotonation, separated roles of the three metal ions, and conformational changes that disfavor incorporation of the incorrect substrate. DNA-embedded ribonucleotides (rNs) are the most common lesion on DNA and a major threat to genome integrity. While kinetics of rN incorporation has been explored and structural studies have revealed that DNA polymerases have a steric gate that destabilizes ribonucleotide triphosphate binding, the mechanism of extension upon rN addition remains poorly characterized. Using steady-state kinetics, static and time-resolved X-ray crystallography with Pol η as a model system, we showed that the extra hydroxyl group on the primer terminus does alter the dynamics of the polymerase active site as well as the catalysis and fidelity of DNA synthesis. During rN extension, Pol η error incorporation efficiency increases significantly across different sequence contexts. Finally, our systematic structural studies suggest that the rN at the primer end improves primer alignment and reduces barriers in C2'-endo to C3'-endo sugar conformational change. Overall, our work provides further mechanistic insights into the effects of rN incorporation on DNA synthesis.
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6
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Freund N, Taylor AI, Arangundy-Franklin S, Subramanian N, Peak-Chew SY, Whitaker AM, Freudenthal BD, Abramov M, Herdewijn P, Holliger P. A two-residue nascent-strand steric gate controls synthesis of 2'-O-methyl- and 2'-O-(2-methoxyethyl)-RNA. Nat Chem 2023; 15:91-100. [PMID: 36229679 PMCID: PMC7614059 DOI: 10.1038/s41557-022-01050-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Accepted: 08/29/2022] [Indexed: 01/17/2023]
Abstract
Steric exclusion is a key element of enzyme substrate specificity, including in polymerases. Such substrate specificity restricts the enzymatic synthesis of 2'-modified nucleic acids, which are of interest in nucleic-acid-based drug development. Here we describe the discovery of a two-residue, nascent-strand, steric control 'gate' in an archaeal DNA polymerase. We show that engineering of the gate to reduce steric bulk in the context of a previously described RNA polymerase activity unlocks the synthesis of 2'-modified RNA oligomers, specifically the efficient synthesis of both defined and random-sequence 2'-O-methyl-RNA (2'OMe-RNA) and 2'-O-(2-methoxyethyl)-RNA (MOE-RNA) oligomers up to 750 nt. This enabled the discovery of RNA endonuclease catalysts entirely composed of 2'OMe-RNA (2'OMezymes) for the allele-specific cleavage of oncogenic KRAS (G12D) and β-catenin CTNNB1 (S33Y) mRNAs, and the elaboration of mixed 2'OMe-/MOE-RNA aptamers with high affinity for vascular endothelial growth factor. Our results open up these 2'-modified RNAs-used in several approved nucleic acid therapeutics-for enzymatic synthesis and a wider exploration in directed evolution and nanotechnology.
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Affiliation(s)
- Niklas Freund
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge, UK
| | - Alexander I Taylor
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge, UK.
- Cambridge Institute of Therapeutic Immunology and Infectious Disease, Jeffrey Cheah Biomedical Centre, Cambridge Biomedical Campus, University of Cambridge, Cambridge, UK.
| | | | - Nithya Subramanian
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge, UK
| | - Sew-Yeu Peak-Chew
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge, UK
| | - Amy M Whitaker
- Laboratory of Genome Maintenance and Structural Biology, Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, Kansas City, KS, USA
- Cancer Epigenetics Institute, Fox Chase Cancer Center, Philadelphia, PA, USA
| | - Bret D Freudenthal
- Laboratory of Genome Maintenance and Structural Biology, Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, Kansas City, KS, USA
| | - Mikhail Abramov
- Medicinal Chemistry, Rega Institute for Medical Research, Katholieke Universiteit Leuven, Leuven, Belgium
| | - Piet Herdewijn
- Medicinal Chemistry, Rega Institute for Medical Research, Katholieke Universiteit Leuven, Leuven, Belgium
| | - Philipp Holliger
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge, UK.
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7
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Zhang K, Pinto A, Cheng LY, Song P, Dai P, Wang M, Rodriguez L, Weller C, Zhang DY. Hairpin Structure Facilitates Multiplex High-Fidelity DNA Amplification in Real-Time Polymerase Chain Reaction. Anal Chem 2022; 94:9586-9594. [PMID: 35749270 DOI: 10.1021/acs.analchem.2c00575] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Clinically and biologically, it is essential to detect rare DNA-sequence variants for early cancer diagnosis or drug-resistance mutation identification. Some of the common quantitative polymerase chain reaction (qPCR)-based variant detection methods are restricted in the limit of detection (LoD) because the DNA polymerases used for these methods have a high polymerase misincorporation rate; thus, the detection sensitivity is sometimes unsatisfactory. With the proofreading activity, high-fidelity (HiFi) DNA polymerases have a 50- to 250-fold higher fidelity. However, there are currently no proper probe-based designs functioning as the fluorescence indicator allowing multiplexed HiFi qPCR reactions, thus restricting the application of HiFi DNA polymerases like the variant detection. We presented the occlusion system, composed of a 5'-overhanged primer with a fluorophore modification and a probe with a short-stem hairpin and a 3' quencher modification. We demonstrated that the occlusion system allowed multiplexing HiFi qPCR reaction, and it was compatible with the current variant-enrichment method to improve the LoD up to 10-fold. Thus, the occlusion system satisfactorily functioned as an efficient fluorescence indicator in HiFi qPCR reactions and allowed the application of HiFi DNA polymerases in variant detection methods to improve detection sensitivity.
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Affiliation(s)
- Kerou Zhang
- Department of Bioengineering, Rice University, Houston, Texas 77030, United States
| | - Alessandro Pinto
- NuProbe USA, 2575 W Bellfort Street, Houston, Texas 77054, United States
| | - Lauren Yuxuan Cheng
- Department of Bioengineering, Rice University, Houston, Texas 77030, United States
| | - Ping Song
- Department of Bioengineering, Rice University, Houston, Texas 77030, United States
| | - Peng Dai
- Department of Bioengineering, Rice University, Houston, Texas 77030, United States
| | - Michael Wang
- Department of Bioengineering, Rice University, Houston, Texas 77030, United States
| | - Luis Rodriguez
- NuProbe USA, 2575 W Bellfort Street, Houston, Texas 77054, United States
| | - Cailin Weller
- NuProbe USA, 2575 W Bellfort Street, Houston, Texas 77054, United States
| | - David Yu Zhang
- Department of Bioengineering, Rice University, Houston, Texas 77030, United States.,Systems, Synthetic, and Physical Biology, Rice University, Houston, Texas 77030, United States
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8
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Ouaray Z, Benner SA, Georgiadis MM, Richards NGJ. Building better polymerases: Engineering the replication of expanded genetic alphabets. J Biol Chem 2020; 295:17046-17059. [PMID: 33004440 PMCID: PMC7863901 DOI: 10.1074/jbc.rev120.013745] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2020] [Revised: 09/30/2020] [Indexed: 11/30/2022] Open
Abstract
DNA polymerases are today used throughout scientific research, biotechnology, and medicine, in part for their ability to interact with unnatural forms of DNA created by synthetic biologists. Here especially, natural DNA polymerases often do not have the "performance specifications" needed for transformative technologies. This creates a need for science-guided rational (or semi-rational) engineering to identify variants that replicate unnatural base pairs (UBPs), unnatural backbones, tags, or other evolutionarily novel features of unnatural DNA. In this review, we provide a brief overview of the chemistry and properties of replicative DNA polymerases and their evolved variants, focusing on the Klenow fragment of Taq DNA polymerase (Klentaq). We describe comparative structural, enzymatic, and molecular dynamics studies of WT and Klentaq variants, complexed with natural or noncanonical substrates. Combining these methods provides insight into how specific amino acid substitutions distant from the active site in a Klentaq DNA polymerase variant (ZP Klentaq) contribute to its ability to replicate UBPs with improved efficiency compared with Klentaq. This approach can therefore serve to guide any future rational engineering of replicative DNA polymerases.
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Affiliation(s)
- Zahra Ouaray
- School of Chemistry, Cardiff University, Park Place, Cardiff, United Kingdom
| | - Steven A Benner
- Foundation for Applied Molecular Evolution, Alachua, Florida, USA
| | - Millie M Georgiadis
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana, USA.
| | - Nigel G J Richards
- School of Chemistry, Cardiff University, Park Place, Cardiff, United Kingdom; Foundation for Applied Molecular Evolution, Alachua, Florida, USA.
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9
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Peralta-Castro A, García-Medel PL, Baruch-Torres N, Trasviña-Arenas CH, Juarez-Quintero V, Morales-Vazquez CM, Brieba LG. Plant Organellar DNA Polymerases Evolved Multifunctionality through the Acquisition of Novel Amino Acid Insertions. Genes (Basel) 2020; 11:genes11111370. [PMID: 33228188 PMCID: PMC7699545 DOI: 10.3390/genes11111370] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Revised: 11/15/2020] [Accepted: 11/17/2020] [Indexed: 12/20/2022] Open
Abstract
The majority of DNA polymerases (DNAPs) are specialized enzymes with specific roles in DNA replication, translesion DNA synthesis (TLS), or DNA repair. The enzymatic characteristics to perform accurate DNA replication are in apparent contradiction with TLS or DNA repair abilities. For instance, replicative DNAPs incorporate nucleotides with high fidelity and processivity, whereas TLS DNAPs are low-fidelity polymerases with distributive nucleotide incorporation. Plant organelles (mitochondria and chloroplast) are replicated by family-A DNA polymerases that are both replicative and TLS DNAPs. Furthermore, plant organellar DNA polymerases from the plant model Arabidopsis thaliana (AtPOLIs) execute repair of double-stranded breaks by microhomology-mediated end-joining and perform Base Excision Repair (BER) using lyase and strand-displacement activities. AtPOLIs harbor three unique insertions in their polymerization domain that are associated with TLS, microhomology-mediated end-joining (MMEJ), strand-displacement, and lyase activities. We postulate that AtPOLIs are able to execute those different functions through the acquisition of these novel amino acid insertions, making them multifunctional enzymes able to participate in DNA replication and DNA repair.
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Affiliation(s)
- Antolín Peralta-Castro
- Laboratorio Nacional de Genomica para la Biodiversidad, Centro de Investigacion y de Estudios Avanzados del IPN, Apartado Postal 629, Irapuato CP 36821, Mexico; (A.P.-C.); (P.L.G.-M.); (N.B.-T.); (C.H.T.-A.); (V.J.-Q.); (C.M.M.-V.)
| | - Paola L. García-Medel
- Laboratorio Nacional de Genomica para la Biodiversidad, Centro de Investigacion y de Estudios Avanzados del IPN, Apartado Postal 629, Irapuato CP 36821, Mexico; (A.P.-C.); (P.L.G.-M.); (N.B.-T.); (C.H.T.-A.); (V.J.-Q.); (C.M.M.-V.)
| | - Noe Baruch-Torres
- Laboratorio Nacional de Genomica para la Biodiversidad, Centro de Investigacion y de Estudios Avanzados del IPN, Apartado Postal 629, Irapuato CP 36821, Mexico; (A.P.-C.); (P.L.G.-M.); (N.B.-T.); (C.H.T.-A.); (V.J.-Q.); (C.M.M.-V.)
| | - Carlos H. Trasviña-Arenas
- Laboratorio Nacional de Genomica para la Biodiversidad, Centro de Investigacion y de Estudios Avanzados del IPN, Apartado Postal 629, Irapuato CP 36821, Mexico; (A.P.-C.); (P.L.G.-M.); (N.B.-T.); (C.H.T.-A.); (V.J.-Q.); (C.M.M.-V.)
- Department of Chemistry, University of California, Davis, One Shields Ave, Davis, CA 95616, USA
| | - Víctor Juarez-Quintero
- Laboratorio Nacional de Genomica para la Biodiversidad, Centro de Investigacion y de Estudios Avanzados del IPN, Apartado Postal 629, Irapuato CP 36821, Mexico; (A.P.-C.); (P.L.G.-M.); (N.B.-T.); (C.H.T.-A.); (V.J.-Q.); (C.M.M.-V.)
| | - Carlos M. Morales-Vazquez
- Laboratorio Nacional de Genomica para la Biodiversidad, Centro de Investigacion y de Estudios Avanzados del IPN, Apartado Postal 629, Irapuato CP 36821, Mexico; (A.P.-C.); (P.L.G.-M.); (N.B.-T.); (C.H.T.-A.); (V.J.-Q.); (C.M.M.-V.)
| | - Luis G. Brieba
- Laboratorio Nacional de Genomica para la Biodiversidad, Centro de Investigacion y de Estudios Avanzados del IPN, Apartado Postal 629, Irapuato CP 36821, Mexico; (A.P.-C.); (P.L.G.-M.); (N.B.-T.); (C.H.T.-A.); (V.J.-Q.); (C.M.M.-V.)
- Correspondence: ; Tel.: +52-462-1663007
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10
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Enzymatic Cleavage of 3'-Esterified Nucleotides Enables a Long, Continuous DNA Synthesis. Sci Rep 2020; 10:7515. [PMID: 32372056 PMCID: PMC7200780 DOI: 10.1038/s41598-020-64541-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Accepted: 04/17/2020] [Indexed: 12/12/2022] Open
Abstract
The reversible dye-terminator (RDT)-based DNA sequencing-by-synthesis (SBS) chemistry has driven the advancement of the next-generation sequencing technologies for the past two decades. The RDT-based SBS chemistry relies on the DNA polymerase reaction to incorporate the RDT nucleotide (NT) for extracting DNA sequence information. The main drawback of this chemistry is the "DNA scar" issue since the removal of dye molecule from the RDT-NT after each sequencing reaction cycle leaves an extra chemical residue in the newly synthesized DNA. To circumvent this problem, we designed a novel class of reversible (2-aminoethoxy)-3-propionyl (Aep)-dNTPs by esterifying the 3'-hydroxyl group (3'-OH) of deoxyribonucleoside triphosphate (dNTP) and examined the NT-incorporation activities by A-family DNA polymerases. Using the large fragment of both Bacillus stearothermophilus (BF) and E. coli DNA polymerase I (KF) as model enzymes, we further showed that both proteins efficiently and faithfully incorporated the 3'-Aep-dNMP. Additionally, we analyzed the post-incorporation product of N + 1 primer and confirmed that the 3'-protecting group of 3'-Aep-dNMP was converted back to a normal 3'-OH after it was incorporated into the growing DNA chain by BF. By applying all four 3'-Aep-dNTPs and BF for an in vitro DNA synthesis reaction, we demonstrated that the enzyme-mediated deprotection of inserted 3'-Aep-dNMP permits a long, continuous, and scar-free DNA synthesis.
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11
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Ghosh S, Goldgur Y, Shuman S. Mycobacterial DNA polymerase I: activities and crystal structures of the POL domain as apoenzyme and in complex with a DNA primer-template and of the full-length FEN/EXO-POL enzyme. Nucleic Acids Res 2020; 48:3165-3180. [PMID: 32034423 PMCID: PMC7102940 DOI: 10.1093/nar/gkaa075] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Revised: 01/23/2020] [Accepted: 02/06/2020] [Indexed: 02/06/2023] Open
Abstract
Mycobacterial Pol1 is a bifunctional enzyme composed of an N-terminal DNA flap endonuclease/5' exonuclease domain (FEN/EXO) and a C-terminal DNA polymerase domain (POL). Here we document additional functions of Pol1: FEN activity on the flap RNA strand of an RNA:DNA hybrid and reverse transcriptase activity on a DNA-primed RNA template. We report crystal structures of the POL domain, as apoenzyme and as ternary complex with 3'-dideoxy-terminated DNA primer-template and dNTP. The thumb, palm, and fingers subdomains of POL form an extensive interface with the primer-template and the triphosphate of the incoming dNTP. Progression from an open conformation of the apoenzyme to a nearly closed conformation of the ternary complex entails a disordered-to-ordered transition of several segments of the thumb and fingers modules and an inward motion of the fingers subdomain-especially the O helix-to engage the primer-template and dNTP triphosphate. Distinctive structural features of mycobacterial Pol1 POL include a manganese binding site in the vestigial 3' exonuclease subdomain and a non-catalytic water-bridged magnesium complex at the protein-DNA interface. We report a crystal structure of the bifunctional FEN/EXO-POL apoenzyme that reveals the positions of two active site metals in the FEN/EXO domain.
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Affiliation(s)
- Shreya Ghosh
- Molecular Biology Program, Sloan-Kettering Institute, New York, NY 10065, USA
| | - Yehuda Goldgur
- Structural Biology Program, Sloan-Kettering Institute, New York, NY 10065, USA
| | - Stewart Shuman
- Molecular Biology Program, Sloan-Kettering Institute, New York, NY 10065, USA
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12
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Abstract
Life on Earth depends on polymerases. These enzymes copy genetic information to produce the DNA and RNA strands at the core of the central dogma. Polymerases act by forming phosphodiester linkages to produce polynucleotide strands. While synthetic chemistry can generate a broad range of alternative genetic materials with unnatural linkages, polymerases have so far been limited to forming O-P bonds. Here, we show that, in fact, unnatural N-P bonds can also be formed by a modified DNA polymerase. This template-directed activity generates complementary strands linked by phosphoramidate (NP) esters, an alternative backbone linkage only known to exist in the laboratory. The emergence of NP-DNA polymerase activity implies the biochemical plausibility of alternative central dogmas for cellular life. All known polymerases copy genetic material by catalyzing phosphodiester bond formation. This highly conserved activity proceeds by a common mechanism, such that incorporated nucleoside analogs terminate chain elongation if the resulting primer strand lacks a terminal hydroxyl group. Even conservatively substituted 3′-amino nucleotides generally act as chain terminators, and no enzymatic pathway for their polymerization has yet been found. Although 3′-amino nucleotides can be chemically coupled to yield stable oligonucleotides containing N3′→P5′ phosphoramidate (NP) bonds, no such internucleotide linkages are known to occur in nature. Here, we report that 3′-amino terminated primers are, in fact, slowly extended by the DNA polymerase from B. stearothermophilus in a template-directed manner. When its cofactor is Ca2+ rather than Mg2+, the reaction is fivefold faster, permitting multiple turnover NP bond formation to yield NP-DNA strands from the corresponding 3′-amino-2′,3′-dideoxynucleoside 5′-triphosphates. A single active site mutation further enhances the rate of NP-DNA synthesis by an additional 21-fold. We show that DNA-dependent NP-DNA polymerase activity depends on conserved active site residues and propose a likely mechanism for this activity based on a series of crystal structures of bound complexes. Our results significantly broaden the catalytic scope of polymerase activity and suggest the feasibility of a genetic transition between native nucleic acids and NP-DNA.
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13
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Endutkin AV, Zharkov DO. Critical Sites of DNA Backbone Integrity for Damaged Base Removal by Formamidopyrimidine-DNA Glycosylase. Biochemistry 2019; 58:2740-2749. [PMID: 31120733 DOI: 10.1021/acs.biochem.9b00134] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
DNA glycosylases, the enzymes that initiate base excision DNA repair, recognize damaged bases through a series of precisely orchestrated movements. Most glycosylases sharply kink the DNA axis at the lesion site and extrude the target base from the DNA double helix into the enzyme's active site. Little attention has been paid so far to the role of the physical continuity of the DNA backbone in allowing the required conformational distortion. Here, we analyze base excision by formamidopyrimidine-DNA glycosylase (Fpg) from substrates keeping all phosphates but containing a nick within three nucleotides of the lesion in either DNA strand. Four phosphoester linkages at the damaged nucleotide and two nucleotides 3' to it were essential for Fpg activity, while the breakage of the others, even at the same critical phosphates, had no effect or even stimulated the reaction. Reduction of the likelihood of hydrogen bonding at the nicks by using dideoxynucleotides as their 3'-terminal groups was more detrimental for the activity. All phosphoester bonds in the complementary strand were dispensable for base excision, but nicks close to the orphaned nucleotide caused early termination of damaged strand cleavage. Elastic network analysis of Fpg-DNA structures showed that the vibrational motions of the critical phosphates are strongly correlated, in part due to the presence of the protein. Overall, our results suggest that mechanical forces propagating along the DNA backbone play a critical role in the correct conformational distortion of DNA by Fpg and possibly by other target base-everting DNA glycosylases.
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Affiliation(s)
- Anton V Endutkin
- SB RAS Institute of Chemical Biology and Fundamental Medicine , 8 Lavrentieva Avenue , Novosibirsk 630090 , Russia.,Novosibirsk State University , 2 Pirogova Street , Novosibirsk 630090 , Russia
| | - Dmitry O Zharkov
- SB RAS Institute of Chemical Biology and Fundamental Medicine , 8 Lavrentieva Avenue , Novosibirsk 630090 , Russia.,Novosibirsk State University , 2 Pirogova Street , Novosibirsk 630090 , Russia
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14
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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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15
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Chim N, Jackson LN, Trinh AM, Chaput JC. Crystal structures of DNA polymerase I capture novel intermediates in the DNA synthesis pathway. eLife 2018; 7:40444. [PMID: 30338759 PMCID: PMC6231770 DOI: 10.7554/elife.40444] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Accepted: 10/18/2018] [Indexed: 11/13/2022] Open
Abstract
High resolution crystal structures of DNA polymerase intermediates are needed to study the mechanism of DNA synthesis in cells. Here we report five crystal structures of DNA polymerase I that capture new conformations for the polymerase translocation and nucleotide pre-insertion steps in the DNA synthesis pathway. We suggest that these new structures, along with previously solved structures, highlight the dynamic nature of the finger subdomain in the enzyme active site. DNA molecules consist of two separate strands that spiral around each other to form a structure called the double helix. Each strand contains repeating units, with every unit consisting of a phosphate group and a sugar molecule bound to one of four bases. The two strands are held together by bonds between the bases. When a cell divides, it needs to make a copy of the DNA, so that each new cell will have an exact replica from the old cell. During this process, the helix unwinds and enzymes called polymerases produce new strands (using the old ones as a template). Each strand is copied by adding new bases one at a time. Every time a new base is added, the polymerases must modify their structures several times. If this process becomes faulty, it can lead to various diseases, including cancer. Scientist often use a technique called X-ray crystallography to study intermediate structures of frozen polymerase crystals as the enzyme constructs DNA. Yet, to fully understand the mechanisms of DNA synthesis all intermediate structures need to be identified. Now, Chim, Jackson et al. used a particular method for making frozen polymerase crytals by allowing the enzyme to add new bases in liquid form. The reaction was then frozen and X-ray crystallography was used to take images. This modified method captured different steps in the process and detailed how the enzyme adjusts its structure as it moves along the template strand. The intermediate structures that Chim, Jackson et al. uncovered may help scientists develop new biotechnologies and medicines. Understanding how polymerases modify their form while making DNA copies could lead to better therapies for diseases in which this process has become faulty, like cancer.
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Affiliation(s)
- Nicholas Chim
- Departments of Pharmaceutical Sciences, University of California, Irvine, California
| | - Lynnette N Jackson
- Departments of Pharmaceutical Sciences, University of California, Irvine, California
| | - Anh M Trinh
- Departments of Pharmaceutical Sciences, University of California, Irvine, California
| | - John C Chaput
- Departments of Pharmaceutical Sciences, University of California, Irvine, California.,Department of Chemistry, University of California, Irvine, California.,Department of Molecular Biology and Biochemistry, University of California, Irvine, California
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16
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Trasviña-Arenas CH, Baruch-Torres N, Cordoba-Andrade FJ, Ayala-García VM, García-Medel PL, Díaz-Quezada C, Peralta-Castro A, Ordaz-Ortiz JJ, Brieba LG. Identification of a unique insertion in plant organellar DNA polymerases responsible for 5'-dRP lyase and strand-displacement activities: Implications for Base Excision Repair. DNA Repair (Amst) 2018. [PMID: 29522990 DOI: 10.1016/j.dnarep.2018.02.010] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Plant mitochondrial and chloroplast genomes encode essential proteins for oxidative phosphorylation and photosynthesis. For proper cellular function, plant organelles must ensure genome integrity. Although plant organelles repair damaged DNA using the multi-enzyme Base Excision Repair (BER) pathway, the details of this pathway in plant organelles are largely unknown. The initial enzymatic steps in BER produce a 5'-deoxyribose phosphate (5'-dRP) moiety that must be removed to allow DNA ligation and in plant organelles, the enzymes responsible for the removal of a 5'-dRP group are unknown. In metazoans, DNA polymerases (DNAPs) remove the 5'-dRP moiety using their intrinsic lyase and/or strand-displacement activities during short or long-patch BER sub-pathways, respectively. The plant model Arabidopsis thaliana encodes two family-A DNAPs paralogs, AtPolIA and AtPolIB, which are the sole DNAPs in plant organelles identified to date. Herein we demonstrate that both AtPolIs present 5'-dRP lyase activities. AtPolIB performs efficient strand-displacement on a BER-associated 1-nt gap DNA substrate, whereas AtPolIA exhibits only moderate strand-displacement activity. Both lyase and strand-displacement activities are dependent on an amino acid insertion that is exclusively present in plant organellar DNAPs. Within this insertion, we identified that residue AtPollB-Lys593 acts as nucleophile for lyase activity. Our results demonstrate that AtPolIs are functionally equipped to play a role in short-patch BER and suggest a major role of AtPolIB in a predicted long-patch BER sub-pathway. We propose that the acquisition of insertion 1 in the polymerization domain of AtPolIs was a key component in their evolution as BER associated and replicative DNAPs.
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Affiliation(s)
- Carlos H Trasviña-Arenas
- Langebio-Cinvestav Sede Irapuato, Km. 9.6 Libramiento Norte Carretera, Irapuato-León, 36821 Irapuato, Guanajuato, Mexico
| | - Noe Baruch-Torres
- Langebio-Cinvestav Sede Irapuato, Km. 9.6 Libramiento Norte Carretera, Irapuato-León, 36821 Irapuato, Guanajuato, Mexico
| | - Francisco J Cordoba-Andrade
- Langebio-Cinvestav Sede Irapuato, Km. 9.6 Libramiento Norte Carretera, Irapuato-León, 36821 Irapuato, Guanajuato, Mexico
| | - Víctor M Ayala-García
- Langebio-Cinvestav Sede Irapuato, Km. 9.6 Libramiento Norte Carretera, Irapuato-León, 36821 Irapuato, Guanajuato, Mexico
| | - Paola L García-Medel
- Langebio-Cinvestav Sede Irapuato, Km. 9.6 Libramiento Norte Carretera, Irapuato-León, 36821 Irapuato, Guanajuato, Mexico
| | - Corina Díaz-Quezada
- Langebio-Cinvestav Sede Irapuato, Km. 9.6 Libramiento Norte Carretera, Irapuato-León, 36821 Irapuato, Guanajuato, Mexico
| | - Antolín Peralta-Castro
- Langebio-Cinvestav Sede Irapuato, Km. 9.6 Libramiento Norte Carretera, Irapuato-León, 36821 Irapuato, Guanajuato, Mexico
| | - José Juan Ordaz-Ortiz
- Langebio-Cinvestav Sede Irapuato, Km. 9.6 Libramiento Norte Carretera, Irapuato-León, 36821 Irapuato, Guanajuato, Mexico
| | - Luis G Brieba
- Langebio-Cinvestav Sede Irapuato, Km. 9.6 Libramiento Norte Carretera, Irapuato-León, 36821 Irapuato, Guanajuato, Mexico.
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17
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Schroeder JW, Yeesin P, Simmons LA, Wang JD. Sources of spontaneous mutagenesis in bacteria. Crit Rev Biochem Mol Biol 2017; 53:29-48. [PMID: 29108429 DOI: 10.1080/10409238.2017.1394262] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Mutations in an organism's genome can arise spontaneously, that is, in the absence of exogenous stress and prior to selection. Mutations are often neutral or deleterious to individual fitness but can also provide genetic diversity driving evolution. Mutagenesis in bacteria contributes to the already serious and growing problem of antibiotic resistance. However, the negative impacts of spontaneous mutagenesis on human health are not limited to bacterial antibiotic resistance. Spontaneous mutations also underlie tumorigenesis and evolution of drug resistance. To better understand the causes of genetic change and how they may be manipulated in order to curb antibiotic resistance or the development of cancer, we must acquire a mechanistic understanding of the major sources of mutagenesis. Bacterial systems are particularly well-suited to studying mutagenesis because of their fast growth rate and the panoply of available experimental tools, but efforts to understand mutagenic mechanisms can be complicated by the experimental system employed. Here, we review our current understanding of mutagenic mechanisms in bacteria and describe the methods used to study mutagenesis in bacterial systems.
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Affiliation(s)
- Jeremy W Schroeder
- a Department of Bacteriology , University of Wisconsin - Madison , Madison , WI , USA
| | - Ponlkrit Yeesin
- a Department of Bacteriology , University of Wisconsin - Madison , Madison , WI , USA
| | - Lyle A Simmons
- b Department of Molecular, Cellular, and Developmental Biology , University of Michigan , Ann Arbor , MI , USA
| | - Jue D Wang
- a Department of Bacteriology , University of Wisconsin - Madison , Madison , WI , USA
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18
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Recent progress in dissecting molecular recognition by DNA polymerases with non-native substrates. Curr Opin Chem Biol 2017; 41:43-49. [PMID: 29096323 DOI: 10.1016/j.cbpa.2017.10.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Accepted: 10/05/2017] [Indexed: 11/22/2022]
Abstract
DNA polymerases must discriminate the correct Watson-Crick base pair-forming deoxynucleoside triphosphate (dNTP) substrate from three other dNTPs and additional triphosphates found in the cell. The rarity of misincorporations in vivo, then, belies the high tolerance for dNTP analogs observed in vitro. Advances over the last 10 years in single-molecule fluorescence and electronic detection of dNTP analog incorporation enable exploration of the mechanism and limits to base discrimination by DNA polymerases. Such studies reveal transient motions of DNA polymerase during substrate recognition and mutagenesis in the context of erroneous dNTP incorporation that can lead to evolution and genetic disease. Further improvements in time resolution and noise reduction of single-molecule studies will uncover deeper mechanistic understanding of this critical, first step in evolution.
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19
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Moon AF, Pryor JM, Ramsden DA, Kunkel TA, Bebenek K, Pedersen LC. Structural accommodation of ribonucleotide incorporation by the DNA repair enzyme polymerase Mu. Nucleic Acids Res 2017; 45:9138-9148. [PMID: 28911097 PMCID: PMC5587726 DOI: 10.1093/nar/gkx527] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2016] [Accepted: 06/23/2017] [Indexed: 02/02/2023] Open
Abstract
While most DNA polymerases discriminate against ribonucleotide triphosphate (rNTP) incorporation very effectively, the Family X member DNA polymerase μ (Pol μ) incorporates rNTPs almost as efficiently as deoxyribonucleotides. To gain insight into how this occurs, here we have used X-ray crystallography to describe the structures of pre- and post-catalytic complexes of Pol μ with a ribonucleotide bound at the active site. These structures reveal that Pol μ binds and incorporates a rNTP with normal active site geometry and no distortion of the DNA substrate or nucleotide. Moreover, a comparison of rNTP incorporation kinetics by wildtype and mutant Pol μ indicates that rNTP accommodation involves synergistic interactions with multiple active site residues not found in polymerases with greater discrimination. Together, the results are consistent with the hypothesis that rNTP incorporation by Pol μ is advantageous in gap-filling synthesis during DNA double strand break repair by nonhomologous end joining, particularly in nonreplicating cells containing very low deoxyribonucleotide concentrations.
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Affiliation(s)
- Andrea F Moon
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA
| | - John M Pryor
- Department of Biochemistry and Biophysics, Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Dale A Ramsden
- Department of Biochemistry and Biophysics, Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Thomas A Kunkel
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA
| | - Katarzyna Bebenek
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA
| | - Lars C Pedersen
- 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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20
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Vyas R, Reed AJ, Raper AT, Zahurancik WJ, Wallenmeyer PC, Suo Z. Structural basis for the D-stereoselectivity of human DNA polymerase β. Nucleic Acids Res 2017; 45:6228-6237. [PMID: 28402499 PMCID: PMC5449621 DOI: 10.1093/nar/gkx252] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Revised: 03/24/2017] [Accepted: 04/03/2017] [Indexed: 12/20/2022] Open
Abstract
Nucleoside reverse transcriptase inhibitors (NRTIs) with L-stereochemistry have long been an effective treatment for viral infections because of the strong D-stereoselectivity exhibited by human DNA polymerases relative to viral reverse transcriptases. The D-stereoselectivity of DNA polymerases has only recently been explored structurally and all three DNA polymerases studied to date have demonstrated unique stereochemical selection mechanisms. Here, we have solved structures of human DNA polymerase β (hPolβ), in complex with single-nucleotide gapped DNA and L-nucleotides and performed pre-steady-state kinetic analysis to determine the D-stereoselectivity mechanism of hPolβ. Beyond a similar 180° rotation of the L-nucleotide ribose ring seen in other studies, the pre-catalytic ternary crystal structures of hPolβ, DNA and L-dCTP or the triphosphate forms of antiviral drugs lamivudine ((-)3TC-TP) and emtricitabine ((-)FTC-TP) provide little structural evidence to suggest that hPolβ follows the previously characterized mechanisms of D-stereoselectivity. Instead, hPolβ discriminates against L-stereochemistry through accumulation of several active site rearrangements that lead to a decreased nucleotide binding affinity and incorporation rate. The two NRTIs escape some of the active site selection through the base and sugar modifications but are selected against through the inability of hPolβ to complete thumb domain closure.
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Affiliation(s)
- Rajan Vyas
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210, USA
| | - Andrew J. Reed
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210, USA
- The Ohio State Biochemistry Program, The Ohio State University, Columbus, OH 43210, USA
| | - Austin T. Raper
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210, USA
- The Ohio State Biochemistry Program, The Ohio State University, Columbus, OH 43210, USA
| | - Walter J. Zahurancik
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210, USA
- The Ohio State Biochemistry Program, The Ohio State University, Columbus, OH 43210, USA
| | - Petra C. Wallenmeyer
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210, USA
| | - Zucai Suo
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210, USA
- The Ohio State Biochemistry Program, The Ohio State University, Columbus, OH 43210, USA
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21
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Wilson KA, Wetmore SD. Combining crystallographic and quantum chemical data to understand DNA-protein π-interactions in nature. Struct Chem 2017. [DOI: 10.1007/s11224-017-0954-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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22
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Wilson KA, Wetmore SD. Molecular Insights into the Translesion Synthesis of Benzyl-Guanine from Molecular Dynamics Simulations: Structural Evidence of Mutagenic and Nonmutagenic Replication. Biochemistry 2017; 56:1841-1853. [PMID: 28290677 DOI: 10.1021/acs.biochem.6b01247] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
DNA can be damaged by many compounds in our environment, and the resulting damaged DNA is commonly replicated by translesion synthesis (TLS) polymerases. Because the mechanism and efficiency of TLS are affected by the type of DNA damage, obtaining information for a variety of DNA adducts is critical. However, there is no structural information for the insertion of a dNTP opposite an O6-dG adduct, which is a particularly harmful class of DNA lesions. We used molecular dynamics (MD) simulations to investigate structural and energetic parameters that dictate preferred dNTP insertion opposite O6-benzyl-guanine (Bz-dG) by DNA polymerase IV, a prototypical TLS polymerase. Specifically, MD simulations were completed on all possible ternary insertion complexes and ternary -1 base deletion complexes with different Bz-dG conformations. Our data suggests that the purines are unlikely to be inserted opposite anti- or syn-Bz-dG, and dTTP is unlikely to be inserted opposite syn-Bz-dG, because of changes in the active site conformation, including critical hydrogen-bonding interactions and/or reaction-ready parameters compared to natural dG replication. In contrast, a preserved active site conformation suggests that dCTP can be inserted opposite either anti- or syn-Bz-dG and dTTP can be inserted opposite anti-Bz-dG. This is the first structural explanation for the experimentally observed preferential insertion of dCTP and misincorporation of dTTP opposite Bz-dG. Furthermore, we provide atomic level insight into why Bz-dG replication does not lead to deletion mutations, which is in contrast with the replication outcomes of other adducts. These findings provide a basis for understanding the replication of related O6-dG adducts.
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Affiliation(s)
- Katie A Wilson
- Department of Chemistry and Biochemistry, University of Lethbridge , 4401 University Drive West, Lethbridge, Alberta T1K 3M4, Canada
| | - Stacey D Wetmore
- Department of Chemistry and Biochemistry, University of Lethbridge , 4401 University Drive West, Lethbridge, Alberta T1K 3M4, Canada
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23
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Yang X, Liu X, Musser DM, Moustafa IM, Arnold JJ, Cameron CE, Boehr DD. Triphosphate Reorientation of the Incoming Nucleotide as a Fidelity Checkpoint in Viral RNA-dependent RNA Polymerases. J Biol Chem 2017; 292:3810-3826. [PMID: 28100782 DOI: 10.1074/jbc.m116.750638] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2016] [Revised: 01/16/2017] [Indexed: 11/06/2022] Open
Abstract
The nucleotide incorporation fidelity of the viral RNA-dependent RNA polymerase (RdRp) is important for maintaining functional genetic information but, at the same time, is also important for generating sufficient genetic diversity to escape the bottlenecks of the host's antiviral response. We have previously shown that the structural dynamics of the motif D loop are closely related to nucleotide discrimination. Previous studies have also suggested that there is a reorientation of the triphosphate of the incoming nucleotide, which is essential before nucleophilic attack from the primer RNA 3'-hydroxyl. Here, we have used 31P NMR with poliovirus RdRp to show that the binding environment of the triphosphate is different when correct versus incorrect nucleotide binds. We also show that amino acid substitutions at residues known to interact with the triphosphate can alter the binding orientation/environment of the nucleotide, sometimes lead to protein conformational changes, and lead to substantial changes in RdRp fidelity. The analyses of other fidelity variants also show that changes in the triphosphate binding environment are not always accompanied by changes in the structural dynamics of the motif D loop or other regions known to be important for RdRp fidelity, including motif B. Altogether, our studies suggest that the conformational changes in motifs B and D, and the nucleoside triphosphate reorientation represent separable, "tunable" fidelity checkpoints.
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Affiliation(s)
| | | | | | - Ibrahim M Moustafa
- Biochemistry and Molecular Biology, Pennsylvania State University, University Park, Pennsylvania 16802
| | - Jamie J Arnold
- Biochemistry and Molecular Biology, Pennsylvania State University, University Park, Pennsylvania 16802
| | - Craig E Cameron
- Biochemistry and Molecular Biology, Pennsylvania State University, University Park, Pennsylvania 16802
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24
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Milton ME, Choe JY, Honzatko RB, Nelson SW. Crystal Structure of the Apicoplast DNA Polymerase from Plasmodium falciparum: The First Look at a Plastidic A-Family DNA Polymerase. J Mol Biol 2016; 428:3920-3934. [PMID: 27487482 DOI: 10.1016/j.jmb.2016.07.016] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Revised: 07/19/2016] [Accepted: 07/22/2016] [Indexed: 11/18/2022]
Abstract
Plasmodium falciparum, the primary cause of malaria, contains a non-photosynthetic plastid called the apicoplast. The apicoplast exists in most members of the phylum Apicomplexa and has its own genome along with organelle-specific enzymes for its replication. The only DNA polymerase found in the apicoplast (apPOL) was putatively acquired through horizontal gene transfer from a bacteriophage and is classified as an atypical A-family polymerase. Here, we present its crystal structure at a resolution of 2.9Å. P. falciparum apPOL, the first structural representative of a plastidic A-family polymerase, diverges from typical A-family members in two of three previously identified signature motifs and in a region not implicated by sequence. Moreover, apPOL has an additional N-terminal subdomain, the absence of which severely diminishes its 3' to 5' exonuclease activity. A compound known to be toxic to Plasmodium is a potent inhibitor of apPOL, suggesting that apPOL is a viable drug target. The structure provides new insights into the structural diversity of A-family polymerases and may facilitate structurally guided antimalarial drug design.
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Affiliation(s)
- Morgan E Milton
- Department of Biochemistry, Biophysics, and Molecular Biology, Iowa State University, Ames, IA 50011, USA
| | - Jun-Yong Choe
- Department of Biochemistry and Molecular Biology, Rosalind Franklin University of Medicine and Science, North Chicago, IL 60064, USA
| | - Richard B Honzatko
- Department of Biochemistry, Biophysics, and Molecular Biology, Iowa State University, Ames, IA 50011, USA.
| | - Scott W Nelson
- Department of Biochemistry, Biophysics, and Molecular Biology, Iowa State University, Ames, IA 50011, USA.
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25
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Wei G, Xi W, Nussinov R, Ma B. Protein Ensembles: How Does Nature Harness Thermodynamic Fluctuations for Life? The Diverse Functional Roles of Conformational Ensembles in the Cell. Chem Rev 2016; 116:6516-51. [PMID: 26807783 PMCID: PMC6407618 DOI: 10.1021/acs.chemrev.5b00562] [Citation(s) in RCA: 253] [Impact Index Per Article: 31.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
All soluble proteins populate conformational ensembles that together constitute the native state. Their fluctuations in water are intrinsic thermodynamic phenomena, and the distributions of the states on the energy landscape are determined by statistical thermodynamics; however, they are optimized to perform their biological functions. In this review we briefly describe advances in free energy landscape studies of protein conformational ensembles. Experimental (nuclear magnetic resonance, small-angle X-ray scattering, single-molecule spectroscopy, and cryo-electron microscopy) and computational (replica-exchange molecular dynamics, metadynamics, and Markov state models) approaches have made great progress in recent years. These address the challenging characterization of the highly flexible and heterogeneous protein ensembles. We focus on structural aspects of protein conformational distributions, from collective motions of single- and multi-domain proteins, intrinsically disordered proteins, to multiprotein complexes. Importantly, we highlight recent studies that illustrate functional adjustment of protein conformational ensembles in the crowded cellular environment. We center on the role of the ensemble in recognition of small- and macro-molecules (protein and RNA/DNA) and emphasize emerging concepts of protein dynamics in enzyme catalysis. Overall, protein ensembles link fundamental physicochemical principles and protein behavior and the cellular network and its regulation.
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Affiliation(s)
- Guanghong Wei
- State Key Laboratory of Surface Physics, Key Laboratory for Computational Physical Sciences (MOE), and Department of Physics, Fudan University, Shanghai, P. R. China
| | - Wenhui Xi
- State Key Laboratory of Surface Physics, Key Laboratory for Computational Physical Sciences (MOE), and Department of Physics, Fudan University, Shanghai, P. R. China
| | - Ruth Nussinov
- Basic Science Program, Leidos Biomedical Research, Inc. Cancer and Inflammation Program, National Cancer Institute, Frederick, Maryland 21702, USA
- Sackler Inst. of Molecular Medicine Department of Human Genetics and Molecular Medicine Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Buyong Ma
- Basic Science Program, Leidos Biomedical Research, Inc. Cancer and Inflammation Program, National Cancer Institute, Frederick, Maryland 21702, USA
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Williams JS, Lujan SA, Kunkel TA. Processing ribonucleotides incorporated during eukaryotic DNA replication. Nat Rev Mol Cell Biol 2016; 17:350-63. [PMID: 27093943 PMCID: PMC5445644 DOI: 10.1038/nrm.2016.37] [Citation(s) in RCA: 125] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The information encoded in DNA is influenced by the presence of non-canonical nucleotides, the most frequent of which are ribonucleotides. In this Review, we discuss recent discoveries about ribonucleotide incorporation into DNA during replication by the three major eukaryotic replicases, DNA polymerases α, δ and ε. The presence of ribonucleotides in DNA causes short deletion mutations and may result in the generation of single- and double-strand DNA breaks, leading to genome instability. We describe how these ribonucleotides are removed from DNA through ribonucleotide excision repair and by topoisomerase I. We discuss the biological consequences and the physiological roles of ribonucleotides in DNA, and consider how deficiencies in their removal from DNA may be important in the aetiology of disease.
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Affiliation(s)
- Jessica S. Williams
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, NIH, DHHS, Research Triangle Park, NC 27709, United States
| | - Scott A. Lujan
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, NIH, DHHS, Research Triangle Park, NC 27709, United States
| | - Thomas A. Kunkel
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, NIH, DHHS, Research Triangle Park, NC 27709, United States
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Meli M, Sustarsic M, Craggs TD, Kapanidis AN, Colombo G. DNA Polymerase Conformational Dynamics and the Role of Fidelity-Conferring Residues: Insights from Computational Simulations. Front Mol Biosci 2016; 3:20. [PMID: 27303671 PMCID: PMC4882331 DOI: 10.3389/fmolb.2016.00020] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Accepted: 05/10/2016] [Indexed: 12/11/2022] Open
Abstract
Herein we investigate the molecular bases of DNA polymerase I conformational dynamics that underlie the replication fidelity of the enzyme. Such fidelity is determined by conformational changes that promote the rejection of incorrect nucleotides before the chemical ligation step. We report a comprehensive atomic resolution study of wild type and mutant enzymes in different bound states and starting from different crystal structures, using extensive molecular dynamics (MD) simulations that cover a total timespan of ~5 ms. The resulting trajectories are examined via a combination of novel methods of internal dynamics and energetics analysis, aimed to reveal the principal molecular determinants for the (de)stabilization of a certain conformational state. Our results show that the presence of fidelity-decreasing mutations or the binding of incorrect nucleotides in ternary complexes tend to favor transitions from closed toward open structures, passing through an ensemble of semi-closed intermediates. The latter ensemble includes the experimentally observed ajar conformation which, consistent with previous experimental observations, emerges as a molecular checkpoint for the selection of the correct nucleotide to incorporate. We discuss the implications of our results for the understanding of the relationships between the structure, dynamics, and function of DNA polymerase I at the atomistic level.
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Affiliation(s)
- Massimiliano Meli
- Computational Biochemistry Group, Istituto di Chimica del Riconoscimento Molecolare, National Research Council of Italy Milano, Italy
| | - Marko Sustarsic
- Clarendon Laboratory, Department of Physics, Biological Physics Research Group, University of Oxford Oxford, UK
| | - Timothy D Craggs
- Clarendon Laboratory, Department of Physics, Biological Physics Research Group, University of Oxford Oxford, UK
| | - Achillefs N Kapanidis
- Clarendon Laboratory, Department of Physics, Biological Physics Research Group, University of Oxford Oxford, UK
| | - Giorgio Colombo
- Computational Biochemistry Group, Istituto di Chimica del Riconoscimento Molecolare, National Research Council of Italy Milano, Italy
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28
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Cerritelli SM, Crouch RJ. The Balancing Act of Ribonucleotides in DNA. Trends Biochem Sci 2016; 41:434-445. [PMID: 26996833 DOI: 10.1016/j.tibs.2016.02.005] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Revised: 02/01/2016] [Accepted: 02/09/2016] [Indexed: 11/28/2022]
Abstract
The abundance of ribonucleotides in DNA remained undetected until recently because they are efficiently removed by the ribonucleotide excision repair (RER) pathway, a process similar to Okazaki fragment (OF) processing after incision by Ribonuclease H2 (RNase H2). All DNA polymerases incorporate ribonucleotides during DNA synthesis. How many, when, and why they are incorporated has been the focus of intense work during recent years by many labs. In this review, we discuss recent advances in ribonucleotide incorporation by eukaryotic DNA polymerases that suggest an evolutionarily conserved role for ribonucleotides in DNA. We also review the data that indicate that removal of ribonucleotides has an important role in maintaining genome stability.
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Affiliation(s)
- Susana M Cerritelli
- Section on Formation of RNA, Division of Developmental Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Robert J Crouch
- Section on Formation of RNA, Division of Developmental Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA.
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29
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Miller BR, Beese LS, Parish CA, Wu EY. The Closing Mechanism of DNA Polymerase I at Atomic Resolution. Structure 2015. [PMID: 26211612 DOI: 10.1016/j.str.2015.06.016] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
DNA polymerases must quickly and accurately distinguish between similar nucleic acids to form Watson-Crick base pairs and avoid DNA replication errors. Deoxynucleoside triphosphate (dNTP) binding to the DNA polymerase active site induces a large conformational change that is difficult to characterize experimentally on an atomic level. Here, we report an X-ray crystal structure of DNA polymerase I bound to DNA in the open conformation with a dNTP present in the active site. We use this structure to computationally simulate the open to closed transition of DNA polymerase in the presence of a Watson-Crick base pair. Our microsecond simulations allowed us to characterize the key steps involved in active site assembly, and propose the sequence of events involved in the prechemistry steps of DNA polymerase catalysis. They also reveal new features of the polymerase mechanism, such as a conserved histidine as a potential proton acceptor from the primer 3'-hydroxyl.
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Affiliation(s)
- Bill R Miller
- Department of Biology, University of Richmond, 28 Westhampton Way, Richmond, VA 23173, USA; Department of Chemistry, University of Richmond, 28 Westhampton Way, Richmond, VA 23173, USA
| | - Lorena S Beese
- Department of Biochemistry, Duke University Medical Center, 255 Nanaline H. Duke Building, Durham, NC 27710, USA
| | - Carol A Parish
- Department of Chemistry, University of Richmond, 28 Westhampton Way, Richmond, VA 23173, USA.
| | - Eugene Y Wu
- Department of Biology, University of Richmond, 28 Westhampton Way, Richmond, VA 23173, USA; Department of Biochemistry, Duke University Medical Center, 255 Nanaline H. Duke Building, Durham, NC 27710, USA.
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30
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Pugliese KM, Gul OT, Choi Y, Olsen TJ, Sims PC, Collins PG, Weiss GA. Processive Incorporation of Deoxynucleoside Triphosphate Analogs by Single-Molecule DNA Polymerase I (Klenow Fragment) Nanocircuits. J Am Chem Soc 2015; 137:9587-94. [PMID: 26147714 DOI: 10.1021/jacs.5b02074] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
DNA polymerases exhibit a surprising tolerance for analogs of deoxyribonucleoside triphosphates (dNTPs), despite the enzymes' highly evolved mechanisms for the specific recognition and discrimination of native dNTPs. Here, individual DNA polymerase I Klenow fragment (KF) molecules were tethered to a single-walled carbon nanotube field-effect transistor (SWCNT-FET) to investigate accommodation of dNTP analogs with single-molecule resolution. Each base incorporation accompanied a change in current with its duration defined by τclosed. Under Vmax conditions, the average time of τclosed was similar for all analog and native dNTPs (0.2 to 0.4 ms), indicating no kinetic impact on this step due to analog structure. Accordingly, the average rates of dNTP analog incorporation were largely determined by durations with no change in current defined by τopen, which includes molecular recognition of the incoming dNTP. All α-thio-dNTPs were incorporated more slowly, at 40 to 65% of the rate for the corresponding native dNTPs. During polymerization with 6-Cl-2APTP, 2-thio-dTTP, or 2-thio-dCTP, the nanocircuit uncovered an alternative conformation represented by positive current excursions that does not occur with native dNTPs. A model consistent with these results invokes rotations by the enzyme's O-helix; this motion can test the stability of nascent base pairs using nonhydrophilic interactions and is allosterically coupled to charged residues near the site of SWCNT attachment. This model with two opposing O-helix motions differs from the previous report in which all current excursions were solely attributed to global enzyme closure and covalent-bond formation. The results suggest the enzyme applies a dynamic stability-checking mechanism for each nascent base pair.
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Affiliation(s)
- Kaitlin M Pugliese
- Departments of †Chemistry, §Physics and Astronomy, and ⊥Molecular Biology and Biochemistry, University of California, Irvine, California 92697, United States
| | - O Tolga Gul
- Departments of †Chemistry, §Physics and Astronomy, and ⊥Molecular Biology and Biochemistry, University of California, Irvine, California 92697, United States
| | - Yongki Choi
- Departments of †Chemistry, §Physics and Astronomy, and ⊥Molecular Biology and Biochemistry, University of California, Irvine, California 92697, United States
| | - Tivoli J Olsen
- Departments of †Chemistry, §Physics and Astronomy, and ⊥Molecular Biology and Biochemistry, University of California, Irvine, California 92697, United States
| | - Patrick C Sims
- Departments of †Chemistry, §Physics and Astronomy, and ⊥Molecular Biology and Biochemistry, University of California, Irvine, California 92697, United States
| | - Philip G Collins
- Departments of †Chemistry, §Physics and Astronomy, and ⊥Molecular Biology and Biochemistry, University of California, Irvine, California 92697, United States
| | - Gregory A Weiss
- Departments of †Chemistry, §Physics and Astronomy, and ⊥Molecular Biology and Biochemistry, University of California, Irvine, California 92697, United States
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Schermerhorn KM, Gardner AF. Pre-steady-state Kinetic Analysis of a Family D DNA Polymerase from Thermococcus sp. 9°N Reveals Mechanisms for Archaeal Genomic Replication and Maintenance. J Biol Chem 2015; 290:21800-10. [PMID: 26160179 PMCID: PMC4571936 DOI: 10.1074/jbc.m115.662841] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2015] [Indexed: 12/18/2022] Open
Abstract
Family D DNA polymerases (polDs) have been implicated as the major replicative polymerase in archaea, excluding the Crenarchaeota branch, and bear little sequence homology to other DNA polymerase families. Here we report a detailed kinetic analysis of nucleotide incorporation and exonuclease activity for a Family D DNA polymerase from Thermococcus sp. 9°N. Pre-steady-state single-turnover nucleotide incorporation assays were performed to obtain the kinetic parameters, kpol and Kd, for correct nucleotide incorporation, incorrect nucleotide incorporation, and ribonucleotide incorporation by exonuclease-deficient polD. Correct nucleotide incorporation kinetics revealed a relatively slow maximal rate of polymerization (kpol ∼ 2.5 s(-1)) and especially tight nucleotide binding (Kd (dNTP) ∼ 1.7 μm), compared with DNA polymerases from Families A, B, C, X, and Y. Furthermore, pre-steady-state nucleotide incorporation assays revealed that polD prevents the incorporation of incorrect nucleotides and ribonucleotides primarily through reduced nucleotide binding affinity. Pre-steady-state single-turnover assays on wild-type 9°N polD were used to examine 3'-5' exonuclease hydrolysis activity in the presence of Mg(2+) and Mn(2+). Interestingly, substituting Mn(2+) for Mg(2+) accelerated hydrolysis rates > 40-fold (kexo ≥ 110 s(-1) versus ≥ 2.5 s(-1)). Preference for Mn(2+) over Mg(2+) in exonuclease hydrolysis activity is a property unique to the polD family. The kinetic assays performed in this work provide critical insight into the mechanisms that polD employs to accurately and efficiently replicate the archaeal genome. Furthermore, despite the unique properties of polD, this work suggests that a conserved polymerase kinetic pathway is present in all known DNA polymerase families.
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32
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Probing the structural and molecular basis of nucleotide selectivity by human mitochondrial DNA polymerase γ. Proc Natl Acad Sci U S A 2015; 112:8596-601. [PMID: 26124101 DOI: 10.1073/pnas.1421733112] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Nucleoside analog reverse transcriptase inhibitors (NRTIs) are the essential components of highly active antiretroviral (HAART) therapy targeting HIV reverse transcriptase (RT). NRTI triphosphates (NRTI-TP), the biologically active forms, act as chain terminators of viral DNA synthesis. Unfortunately, NRTIs also inhibit human mitochondrial DNA polymerase (Pol γ), causing unwanted mitochondrial toxicity. Understanding the structural and mechanistic differences between Pol γ and RT in response to NRTIs will provide invaluable insight to aid in designing more effective drugs with lower toxicity. The NRTIs emtricitabine [(-)-2,3'-dideoxy-5-fluoro-3'-thiacytidine, (-)-FTC] and lamivudine, [(-)-2,3'-dideoxy-3'-thiacytidine, (-)-3TC] are both potent RT inhibitors, but Pol γ discriminates against (-)-FTC-TP by two orders of magnitude better than (-)-3TC-TP. Furthermore, although (-)-FTC-TP is only slightly more potent against HIV RT than its enantiomer (+)-FTC-TP, it is discriminated by human Pol γ four orders of magnitude more efficiently than (+)-FTC-TP. As a result, (-)-FTC is a much less toxic NRTI. Here, we present the structural and kinetic basis for this striking difference by identifying the discriminator residues of drug selectivity in both viral and human enzymes responsible for substrate selection and inhibitor specificity. For the first time, to our knowledge, this work illuminates the mechanism of (-)-FTC-TP differential selectivity and provides a structural scaffold for development of novel NRTIs with lower toxicity.
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33
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Szymanski MR, Kuznetsov VB, Shumate C, Meng Q, Lee YS, Patel G, Patel S, Yin YW. Structural basis for processivity and antiviral drug toxicity in human mitochondrial DNA replicase. EMBO J 2015; 34:1959-70. [PMID: 26056153 DOI: 10.15252/embj.201591520] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2015] [Accepted: 05/18/2015] [Indexed: 11/09/2022] Open
Abstract
The human DNA polymerase gamma (Pol γ) is responsible for DNA replication in mitochondria. Pol γ is particularly susceptible to inhibition by dideoxynucleoside-based inhibitors designed to fight viral infection. Here, we report crystal structures of the replicating Pol γ-DNA complex bound to either substrate or zalcitabine, an inhibitor used for HIV reverse transcriptase. The structures reveal that zalcitabine binds to the Pol γ active site almost identically to the substrate dCTP, providing a structural basis for Pol γ-mediated drug toxicity. When compared to the apo form, Pol γ undergoes intra- and inter-subunit conformational changes upon formation of the ternary complex with primer/template DNA and substrate. We also find that the accessory subunit Pol γB, which lacks intrinsic enzymatic activity and does not contact the primer/template DNA directly, serves as an allosteric regulator of holoenzyme activities. The structures presented here suggest a mechanism for processivity of the holoenzyme and provide a model for understanding the deleterious effects of Pol γ mutations in human disease. Crystal structures of the mitochondrial DNA polymerase, Pol γ, in complex with substrate or antiviral inhibitor zalcitabine provide a basis for understanding Pol γ-mediated drug toxicity.
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Affiliation(s)
- Michal R Szymanski
- Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX, USA Sealy Center for Structural Biology, University of Texas Medical Branch, Galveston, TX, USA
| | - Vladmir B Kuznetsov
- Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX, USA Sealy Center for Structural Biology, University of Texas Medical Branch, Galveston, TX, USA
| | - Christie Shumate
- Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX, USA Sealy Center for Structural Biology, University of Texas Medical Branch, Galveston, TX, USA
| | - Qingchao Meng
- Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX, USA
| | - Young-Sam Lee
- Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX, USA
| | - Gayatri Patel
- Biochemistry and Molecular Biology, Rutgers-Robert Wood Johnson Medical School, Piscataway, NJ, USA
| | - Smita Patel
- Biochemistry and Molecular Biology, Rutgers-Robert Wood Johnson Medical School, Piscataway, NJ, USA
| | - Y Whitney Yin
- Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX, USA Sealy Center for Structural Biology, University of Texas Medical Branch, Galveston, TX, USA
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Morin JA, Cao FJ, Lázaro JM, Arias-Gonzalez JR, Valpuesta JM, Carrascosa JL, Salas M, Ibarra B. Mechano-chemical kinetics of DNA replication: identification of the translocation step of a replicative DNA polymerase. Nucleic Acids Res 2015; 43:3643-52. [PMID: 25800740 PMCID: PMC4402526 DOI: 10.1093/nar/gkv204] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Revised: 02/14/2015] [Accepted: 02/27/2015] [Indexed: 11/25/2022] Open
Abstract
During DNA replication replicative polymerases move in discrete mechanical steps along the DNA template. To address how the chemical cycle is coupled to mechanical motion of the enzyme, here we use optical tweezers to study the translocation mechanism of individual bacteriophage Phi29 DNA polymerases during processive DNA replication. We determine the main kinetic parameters of the nucleotide incorporation cycle and their dependence on external load and nucleotide (dNTP) concentration. The data is inconsistent with power stroke models for translocation, instead supports a loose-coupling mechanism between chemical catalysis and mechanical translocation during DNA replication. According to this mechanism the DNA polymerase works by alternating between a dNTP/PPi-free state, which diffuses thermally between pre- and post-translocated states, and a dNTP/PPi-bound state where dNTP binding stabilizes the post-translocated state. We show how this thermal ratchet mechanism is used by the polymerase to generate work against large opposing loads (∼50 pN).
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Affiliation(s)
- José A Morin
- Instituto Madrileño de Estudios Avanzados en Nanociencia, IMDEA Nanociencia, 28049 Madrid, Spain
| | - Francisco J Cao
- Departamento Física Atómica, Molecular y Nuclear, Universidad Complutense, 28040 Madrid, Spain
| | - José M Lázaro
- Centro de Biología Molecular 'Severo Ochoa' (CSIC-UAM), Universidad Autónoma, Cantoblanco, 28049 Madrid, Spain
| | - J Ricardo Arias-Gonzalez
- Instituto Madrileño de Estudios Avanzados en Nanociencia (IMDEA Nanociencia) & CNB-CSIC-IMDEA Nanociencia Associated Unit 'Unidad de Nanobiotecnología', 28049 Madrid, Spain
| | - José M Valpuesta
- Centro Nacional de Biotecnología (CNB-CSIC), 28049 Madrid, Spain
| | - José L Carrascosa
- Instituto Madrileño de Estudios Avanzados en Nanociencia (IMDEA Nanociencia) & CNB-CSIC-IMDEA Nanociencia Associated Unit 'Unidad de Nanobiotecnología', 28049 Madrid, Spain Centro Nacional de Biotecnología (CNB-CSIC), 28049 Madrid, Spain
| | - Margarita Salas
- Centro de Biología Molecular 'Severo Ochoa' (CSIC-UAM), Universidad Autónoma, Cantoblanco, 28049 Madrid, Spain
| | - Borja Ibarra
- Instituto Madrileño de Estudios Avanzados en Nanociencia (IMDEA Nanociencia) & CNB-CSIC-IMDEA Nanociencia Associated Unit 'Unidad de Nanobiotecnología', 28049 Madrid, Spain
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Beese L, Wang W, Hellinga H. A Unified Picture of Nucleotide Selection by a High Fidelity DNA Polymerase I. FASEB J 2015. [DOI: 10.1096/fasebj.29.1_supplement.225.2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Lorena Beese
- Department of BiochemistryDuke UniversityUnited States
| | - W. Wang
- Department of BiochemistryDuke UniversityUnited States
| | - H. Hellinga
- Department of BiochemistryDuke UniversityUnited States
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Kent T, Chandramouly G, McDevitt SM, Ozdemir AY, Pomerantz RT. Mechanism of microhomology-mediated end-joining promoted by human DNA polymerase θ. Nat Struct Mol Biol 2015; 22:230-7. [PMID: 25643323 PMCID: PMC4351179 DOI: 10.1038/nsmb.2961] [Citation(s) in RCA: 222] [Impact Index Per Article: 24.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Accepted: 12/22/2014] [Indexed: 12/25/2022]
Abstract
Microhomology-mediated end-joining (MMEJ) is an error-prone alternative double-strand break-repair pathway that uses sequence microhomology to recombine broken DNA. Although MMEJ has been implicated in cancer development, the mechanism of this pathway is unknown. We demonstrate that purified human DNA polymerase θ (Polθ) performs MMEJ of DNA containing 3' single-strand DNA overhangs with ≥2 bp of homology, including DNA modeled after telomeres, and show that MMEJ is dependent on Polθ in human cells. Our data support a mechanism whereby Polθ facilitates end-joining and microhomology annealing, then uses the opposing overhang as a template in trans to stabilize the DNA synapse. Polθ exhibits a preference for DNA containing a 5'-terminal phosphate, similarly to polymerases involved in nonhomologous end-joining. Finally, we identify a conserved loop domain that is essential for MMEJ and higher-order structures of Polθ that probably promote DNA synapse formation.
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Affiliation(s)
- Tatiana Kent
- Fels Institute for Cancer Research and Molecular Biology, Temple University School of Medicine, Philadelphia, Pennsylvania, USA
- Department of Biochemistry, Temple University School of Medicine, Philadelphia, Pennsylvania, USA
| | - Gurushankar Chandramouly
- Fels Institute for Cancer Research and Molecular Biology, Temple University School of Medicine, Philadelphia, Pennsylvania, USA
- Department of Biochemistry, Temple University School of Medicine, Philadelphia, Pennsylvania, USA
| | - Shane Michael McDevitt
- Fels Institute for Cancer Research and Molecular Biology, Temple University School of Medicine, Philadelphia, Pennsylvania, USA
- Department of Biochemistry, Temple University School of Medicine, Philadelphia, Pennsylvania, USA
| | - Ahmet Y. Ozdemir
- Fels Institute for Cancer Research and Molecular Biology, Temple University School of Medicine, Philadelphia, Pennsylvania, USA
- Department of Biochemistry, Temple University School of Medicine, Philadelphia, Pennsylvania, USA
| | - Richard T. Pomerantz
- Fels Institute for Cancer Research and Molecular Biology, Temple University School of Medicine, Philadelphia, Pennsylvania, USA
- Department of Biochemistry, Temple University School of Medicine, Philadelphia, Pennsylvania, USA
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37
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Wilson KA, Wells RA, Abendong MN, Anderson CB, Kung RW, Wetmore SD. Landscape of π-π and sugar-π contacts in DNA-protein interactions. J Biomol Struct Dyn 2015; 34:184-200. [PMID: 25723403 DOI: 10.1080/07391102.2015.1013157] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
There were 1765 contacts identified between DNA nucleobases or deoxyribose and cyclic (W, H, F, Y) or acyclic (R, E, D) amino acids in 672 X-ray structures of DNA-protein complexes. In this first study to compare π-interactions between the cyclic and acyclic amino acids, visual inspection was used to categorize amino acid interactions as nucleobase π-π (according to biological edge) or deoxyribose sugar-π (according to sugar edge). Overall, 54% of contacts are nucleobase π-π interactions, which involve all amino acids, but are more common for Y, F, and R, and involve all DNA nucleobases with similar frequencies. Among binding arrangements, cyclic amino acids prefer more planar (stacked) π-systems than the acyclic counterparts. Although sugar-π interactions were only previously identified with the cyclic amino acids and were found to be less common (38%) than nucleobase-cyclic amino acid contacts, sugar-π interactions are more common than nucleobase π-π contacts for the acyclic series (61% of contacts). Similar to DNA-protein π-π interactions, sugar-π contacts most frequently involve Y and R, although all amino acids adopt many binding orientations relative to deoxyribose. These DNA-protein π-interactions stabilize biological systems, by up to approximately -40 kJ mol(-1) for neutral nucleobase or sugar-amino acid interactions, but up to approximately -95 kJ mol(-1) for positively or negatively charged contacts. The high frequency and strength, despite variation in structure and composition, of these π-interactions point to an important function in biological systems.
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Affiliation(s)
- Katie A Wilson
- a Department of Chemistry and Biochemistry , University of Lethbridge , 4401 University Drive West, Lethbridge , AB T1K 3M4 , Canada
| | - Rachael A Wells
- a Department of Chemistry and Biochemistry , University of Lethbridge , 4401 University Drive West, Lethbridge , AB T1K 3M4 , Canada
| | - Minette N Abendong
- a Department of Chemistry and Biochemistry , University of Lethbridge , 4401 University Drive West, Lethbridge , AB T1K 3M4 , Canada
| | - Colin B Anderson
- a Department of Chemistry and Biochemistry , University of Lethbridge , 4401 University Drive West, Lethbridge , AB T1K 3M4 , Canada
| | - Ryan W Kung
- a Department of Chemistry and Biochemistry , University of Lethbridge , 4401 University Drive West, Lethbridge , AB T1K 3M4 , Canada
| | - Stacey D Wetmore
- a Department of Chemistry and Biochemistry , University of Lethbridge , 4401 University Drive West, Lethbridge , AB T1K 3M4 , Canada
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38
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Nevin P, Engen JR, Beuning PJ. Steric gate residues of Y-family DNA polymerases DinB and pol kappa are crucial for dNTP-induced conformational change. DNA Repair (Amst) 2015; 29:65-73. [PMID: 25684709 DOI: 10.1016/j.dnarep.2015.01.012] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Revised: 01/22/2015] [Accepted: 01/23/2015] [Indexed: 01/08/2023]
Abstract
Discrimination against ribonucleotides by DNA polymerases is critical to preserve DNA integrity. For many DNA polymerases, including those of the Y family, rNTP discrimination has been attributed to steric clashes between a residue near the active site, the steric gate, and the 2'-hydroxyl of the incoming rNTP. Here we used hydrogen/deuterium exchange (HDX) mass spectrometry (MS) to probe the effects of the steric gate in the Y-family DNA polymerases Escherichia coli DinB and human DNA pol κ. Formation of a ternary complex with a G:dCTP base pair in the active site resulted in slower hydrogen exchange relative to a ternary complex with G:rCTP in the active site. The protection from exchange was localized to regions both distal and proximal to the active site, suggesting that DinB and DNA pol κ adopt different conformations depending on the sugar of the incoming nucleotide. In contrast, when the respective steric gate residues were mutated to alanine, the differences in HDX between the dNTP- and rNTP-bound ternary complexes were attenuated such that for DinB(F13A) and pol κ(Y112A), ternary complexes with either G:dCTP or G:rCTP base pairs had similar HDX profiles. Furthermore, the HDX in these ternary complexes resembled that of the rCTP-bound state rather than the dCTP-bound state of the wild-type enzymes. Primer extension assays confirmed that DinB(F13A) and pol κ(Y112A) do not discriminate against rNTPs to the same extent as the wild-type enzymes. Our observations indicate that the steric gate is crucial for rNTP discrimination because of its role in specifically promoting a dNTP-induced conformational change and that rNTP discrimination occurs in a relatively closed state of the polymerases.
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Affiliation(s)
- Philip Nevin
- Department of Chemistry and Chemical Biology, Northeastern University, 360 Huntington Avenue, Boston, MA 02115, USA
| | - John R Engen
- Department of Chemistry and Chemical Biology, Northeastern University, 360 Huntington Avenue, Boston, MA 02115, USA
| | - Penny J Beuning
- Department of Chemistry and Chemical Biology, Northeastern University, 360 Huntington Avenue, Boston, MA 02115, USA.
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39
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Wu EY, Walsh AR, Materne EC, Hiltner EP, Zielinski B, Miller BR, Mawby L, Modeste E, Parish CA, Barnes WM, Kermekchiev MB. A conservative isoleucine to leucine mutation causes major rearrangements and cold sensitivity in KlenTaq1 DNA polymerase. Biochemistry 2015; 54:881-9. [PMID: 25537790 PMCID: PMC4310628 DOI: 10.1021/bi501198f] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Assembly of polymerase chain reactions at room temperature can sometimes lead to low yields or unintentional products due to mispriming. Mutation of isoleucine 707 to leucine in DNA polymerase I from Thermus aquaticus substantially decreases its activity at room temperature without compromising its ability to amplify DNA. To understand why a conservative change to the enzyme over 20 Å from the active site can have a large impact on its activity at low temperature, we solved the X-ray crystal structure of the large (5'-to-3' exonuclease-deleted) fragment of Taq DNA polymerase containing the cold-sensitive mutation in the ternary (E-DNA-ddNTP) and binary (E-DNA) complexes. The I707L KlenTaq1 ternary complex was identical to the wild-type in the closed conformation except for the mutation and a rotamer change in nearby phenylalanine 749, suggesting that the enzyme should remain active. However, soaking out of the nucleotide substrate at low temperature results in an altered binary complex made possible by the rotamer change at F749 near the tip of the polymerase O-helix. Surprisingly, two adenosines in the 5'-template overhang fill the vacated active site by stacking with the primer strand, thereby blocking the active site at low temperature. Replacement of the two overhanging adenosines with pyrimidines substantially increased activity at room temperature by keeping the template overhang out of the active site, confirming the importance of base stacking. These results explain the cold-sensitive phenotype of the I707L mutation in KlenTaq1 and serve as an example of a large conformational change affected by a conservative mutation.
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Affiliation(s)
- Eugene Y Wu
- Department of Biology and ‡Department of Chemistry, University of Richmond , Richmond, Virginia 23173, United States
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40
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Wilson KA, Wetmore SD. A Survey of DNA–Protein π–Interactions: A Comparison of Natural Occurrences and Structures, and Computationally Predicted Structures and Strengths. CHALLENGES AND ADVANCES IN COMPUTATIONAL CHEMISTRY AND PHYSICS 2015. [DOI: 10.1007/978-3-319-14163-3_17] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
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41
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Wang B, Opron K, Burton ZF, Cukier RI, Feig M. Five checkpoints maintaining the fidelity of transcription by RNA polymerases in structural and energetic details. Nucleic Acids Res 2014; 43:1133-46. [PMID: 25550432 PMCID: PMC4333413 DOI: 10.1093/nar/gku1370] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Transcriptional fidelity, which prevents the misincorporation of incorrect nucleoside monophosphates in RNA, is essential for life. Results from molecular dynamics (MD) simulations of eukaryotic RNA polymerase (RNAP) II and bacterial RNAP with experimental data suggest that fidelity may involve as many as five checkpoints. Using MD simulations, the effects of different active site NTPs in both open and closed trigger loop (TL) structures of RNAPs are compared. Unfavorable initial binding of mismatched substrates in the active site with an open TL is proposed to be the first fidelity checkpoint. The leaving of an incorrect substrate is much easier than a correct one energetically from the umbrella sampling simulations. Then, the closing motion of the TL, required for catalysis, is hindered by the presence of mismatched NTPs. Mismatched NTPs also lead to conformational changes in the active site, which perturb the coordination of magnesium ions and likely affect the ability to proceed with catalysis. This step appears to be the most important checkpoint for deoxy-NTP discrimination. Finally, structural perturbations in the template DNA and the nascent RNA in the presence of mismatches likely hinder nucleotide addition and provide the structural foundation for backtracking followed by removing erroneously incorporated nucleotides during proofreading.
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Affiliation(s)
- Beibei Wang
- Department of Biochemistry & Molecular Biology, Michigan State University, East Lansing, MI 48824, USA
| | - Kristopher Opron
- Department of Biochemistry & Molecular Biology, Michigan State University, East Lansing, MI 48824, USA
| | - Zachary F Burton
- Department of Biochemistry & Molecular Biology, Michigan State University, East Lansing, MI 48824, USA
| | - Robert I Cukier
- Department of Chemistry, Michigan State University, East Lansing, MI 48824, USA
| | - Michael Feig
- Department of Biochemistry & Molecular Biology, Michigan State University, East Lansing, MI 48824, USA Department of Chemistry, Michigan State University, East Lansing, MI 48824, USA
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42
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Dahl JM, Wang H, Lázaro JM, Salas M, Lieberman KR. Kinetic mechanisms governing stable ribonucleotide incorporation in individual DNA polymerase complexes. Biochemistry 2014; 53:8061-76. [PMID: 25478721 PMCID: PMC4283934 DOI: 10.1021/bi501216a] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Ribonucleoside triphosphates (rNTPs) are frequently incorporated during DNA synthesis by replicative DNA polymerases (DNAPs), and once incorporated are not efficiently edited by the DNAP exonucleolytic function. We examined the kinetic mechanisms that govern selection of complementary deoxyribonucleoside triphosphates (dNTPs) over complementary rNTPs and that govern the probability of a complementary ribonucleotide at the primer terminus escaping exonucleolytic editing and becoming stably incorporated. We studied the quantitative responses of individual Φ29 DNAP complexes to ribonucleotides using a kinetic framework, based on our prior work, in which transfer of the primer strand from the polymerase to exonuclease site occurs prior to translocation, and translocation precedes dNTP binding. We determined transition rates between the pre-translocation and post-translocation states, between the polymerase and exonuclease sites, and for dNTP or rNTP binding, with single-nucleotide spatial precision and submillisecond temporal resolution, from ionic current time traces recorded when individual DNAP complexes are held atop a nanopore in an electric field. The predominant response to the presence of a ribonucleotide in Φ29 DNAP complexes before and after covalent incorporation is significant destabilization, relative to the presence of a deoxyribonucleotide. This destabilization is manifested in the post-translocation state prior to incorporation as a substantially higher rNTP dissociation rate and manifested in the pre-translocation state after incorporation as rate increases for both primer strand transfer to the exonuclease site and the forward translocation, with the probability of editing not directly increased. In the post-translocation state, the primer terminal 2'-OH group also destabilizes dNTP binding.
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Affiliation(s)
- Joseph M Dahl
- Department of Biomolecular Engineering, ‡Department of Applied Mathematics and Statistics, and §Department of Computer Engineering, Baskin School of Engineering, University of California , Santa Cruz, California 95064, United States
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43
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Wilson KA, Kellie JL, Wetmore SD. DNA-protein π-interactions in nature: abundance, structure, composition and strength of contacts between aromatic amino acids and DNA nucleobases or deoxyribose sugar. Nucleic Acids Res 2014; 42:6726-41. [PMID: 24744240 PMCID: PMC4041443 DOI: 10.1093/nar/gku269] [Citation(s) in RCA: 107] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Four hundred twenty-eight high-resolution DNA-protein complexes were chosen for a bioinformatics study. Although 164 crystal structures (38% of those searched) contained no interactions, 574 discrete π-contacts between the aromatic amino acids and the DNA nucleobases or deoxyribose were identified using strict criteria, including visual inspection. The abundance and structure of the interactions were determined by unequivocally classifying the contacts as either π-π stacking, π-π T-shaped or sugar-π contacts. Three hundred forty-four nucleobase-amino acid π-π contacts (60% of all interactions identified) were identified in 175 of the crystal structures searched. Unprecedented in the literature, 230 DNA-protein sugar-π contacts (40% of all interactions identified) were identified in 137 crystal structures, which involve C-H···π and/or lone-pair···π interactions, contain any amino acid and can be classified according to sugar atoms involved. Both π-π and sugar-π interactions display a range of relative monomer orientations and therefore interaction energies (up to -50 (-70) kJ mol(-1) for neutral (charged) interactions as determined using quantum chemical calculations). In general, DNA-protein π-interactions are more prevalent than perhaps currently accepted and the role of such interactions in many biological processes may yet to be uncovered.
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Affiliation(s)
- Katie A Wilson
- Department of Chemistry and Biochemistry, University of Lethbridge, 4401 University Drive West, Lethbridge, AB, T1K 3M4, Canada
| | - Jennifer L Kellie
- Department of Chemistry and Biochemistry, University of Lethbridge, 4401 University Drive West, Lethbridge, AB, T1K 3M4, Canada
| | - Stacey D Wetmore
- Department of Chemistry and Biochemistry, University of Lethbridge, 4401 University Drive West, Lethbridge, AB, T1K 3M4, Canada
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44
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Abstract
While primordial life is thought to have been RNA-based (Cech, Cold Spring Harbor Perspect. Biol. 4 (2012) a006742), all living organisms store genetic information in DNA, which is chemically more stable. Distinctions between the RNA and DNA worlds and our views of "DNA" synthesis continue to evolve as new details emerge on the incorporation, repair and biological effects of ribonucleotides in DNA genomes of organisms from bacteria through humans.
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Affiliation(s)
- Jessica S Williams
- Laboratory of Molecular Genetics and Laboratory of Structural Biology, National Institute of Environmental Health Sciences, NIH, DHHS, Research Triangle Park, NC 27709, United States
| | - Thomas A Kunkel
- Laboratory of Molecular Genetics and Laboratory of Structural Biology, National Institute of Environmental Health Sciences, NIH, DHHS, Research Triangle Park, NC 27709, United States.
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45
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Blatter N, Bergen K, Nolte O, Welte W, Diederichs K, Mayer J, Wieland M, Marx A. Structure and function of an RNA-reading thermostable DNA polymerase. Angew Chem Int Ed Engl 2013; 52:11935-9. [PMID: 24106012 DOI: 10.1002/anie.201306655] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2013] [Revised: 08/16/2013] [Indexed: 12/30/2022]
Affiliation(s)
- Nina Blatter
- Departments of Chemistry and Biology, Konstanz Research School Chemical Biology, University of Konstanz, Universitätsstrasse 10, 78457 Konstanz (Germany)
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46
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Blatter N, Bergen K, Nolte O, Welte W, Diederichs K, Mayer J, Wieland M, Marx A. Struktur und Funktion einer RNA-lesenden thermostabilen DNA-Polymerase. Angew Chem Int Ed Engl 2013. [DOI: 10.1002/ange.201306655] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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47
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Bermek O, Grindley NDF, Joyce CM. Prechemistry nucleotide selection checkpoints in the reaction pathway of DNA polymerase I and roles of glu710 and tyr766. Biochemistry 2013; 52:6258-74. [PMID: 23937394 PMCID: PMC3770053 DOI: 10.1021/bi400837k] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
![]()
The accuracy of high-fidelity DNA
polymerases such as DNA polymerase
I (Klenow fragment) is governed by conformational changes early in
the reaction pathway that serve as fidelity checkpoints, identifying
inappropriate template–nucleotide pairings. The fingers-closing
transition (detected by a fluorescence resonance energy transfer-based
assay) is the unique outcome of binding a correct incoming nucleotide,
both complementary to the templating base and with a deoxyribose (rather
than ribose) sugar structure. Complexes with mispaired dNTPs or complementary
rNTPs are arrested at an earlier stage, corresponding to a partially
closed fingers conformation, in which weak binding of DNA and nucleotide
promote dissociation and resampling of the substrate pool. A 2-aminopurine
fluorescence probe on the DNA template provides further information
about the steps preceding fingers closing. A characteristic 2-aminopurine
signal is observed on binding a complementary nucleotide, regardless
of whether the sugar is deoxyribose or ribose. However, mispaired
dNTPs show entirely different behavior. Thus, a fidelity checkpoint
ahead of fingers closing is responsible for distinguishing complementary
from noncomplementary nucleotides and routing them toward different
outcomes. The E710A mutator polymerase has a defect in the early fidelity
checkpoint such that some complementary dNTPs are treated as if they
were mispaired. In the Y766A mutant, the early checkpoint functions
normally, but some correctly paired dNTPs do not efficiently undergo
fingers closing. Thus, both mutator alleles cause a blurring of the
distinction between correct and incorrect base pairs and result in
a larger fraction of errors passing through the prechemistry fidelity
checkpoints.
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Affiliation(s)
- Oya Bermek
- Department of Molecular Biophysics and Biochemistry, Yale University , New Haven, Connecticut 06520, United States
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48
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Gouge J, Rosario S, Romain F, Beguin P, Delarue M. Structures of intermediates along the catalytic cycle of terminal deoxynucleotidyltransferase: dynamical aspects of the two-metal ion mechanism. J Mol Biol 2013; 425:4334-52. [PMID: 23856622 DOI: 10.1016/j.jmb.2013.07.009] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2013] [Revised: 06/28/2013] [Accepted: 07/03/2013] [Indexed: 11/19/2022]
Abstract
Terminal deoxynucleotidyltransferase (Tdt) is a non-templated eukaryotic DNA polymerase of the polX family that is responsible for the random addition of nucleotides at the V(D)J junctions of immunoglobulins and T-cell receptors. Here we describe a series of high-resolution X-ray structures that mimic the pre-catalytic state, the post-catalytic state and a competent state that can be transformed into the two other ones in crystallo via the addition of dAMPcPP and Zn(2+), respectively. We examined the effect of Mn(2+), Co(2+) and Zn(2+) because they all have a marked influence on the kinetics of the reaction. We demonstrate a dynamic role of divalent transition metal ions bound to site A: (i) Zn(2+) (or Co(2+)) in Metal A site changes coordination from octahedral to tetrahedral after the chemical step, which explains the known higher affinity of Tdt for the primer strand when these ions are present, and (ii) metal A has to leave to allow the translocation of the primer strand and to clear the active site, a typical feature for a ratchet-like mechanism. Except for Zn(2+), the sugar puckering of the primer strand 3' terminus changes from C2'-endo to C3'-endo during catalysis. In addition, our data are compatible with a scheme where metal A is the last component that binds to the active site to complete its productive assembly, as already inferred in human pol beta. The new structures have potential implications for modeling pol mu, a closely related polX implicated in the repair of DNA double-strand breaks, in a complex with a DNA synapsis.
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Affiliation(s)
- Jérôme Gouge
- Unité de Dynamique Structurale des Macromolécules, Institut Pasteur, UMR 3528 du CNRS, 25 rue du Dr Roux, 75015 Paris, France
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49
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Vaidyanathan VG, Liang F, Beard WA, Shock DD, Wilson SH, Cho BP. Insights into the conformation of aminofluorene-deoxyguanine adduct in a DNA polymerase active site. J Biol Chem 2013; 288:23573-85. [PMID: 23798703 DOI: 10.1074/jbc.m113.476150] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The active site conformation of the mutagenic fluoroaminofluorene-deoxyguanine adduct (dG-FAF, N-(2'-deoxyguanosin-8-yl)-7-fluoro-2-aminofluorene) has been investigated in the presence of Klenow fragment of Escherichia coli DNA polymerase I (Kfexo(-)) and DNA polymerase β (pol β) using (19)F NMR, insertion assay, and surface plasmon resonance. In a single nucleotide gap, the dG-FAF adduct adopts both a major-groove- oriented and base-displaced stacked conformation, and this heterogeneity is retained upon binding pol β. The addition of a non-hydrolysable 2'-deoxycytosine-5'-[(α,β)-methyleno]triphosphate (dCMPcPP) nucleotide analog to the binary complex results in an increase of the major groove conformation of the adduct at the expense of the stacked conformation. Similar results were obtained with the addition of an incorrect dAMPcPP analog but with formation of the minor groove binding conformer. In contrast, dG-FAF adduct at the replication fork for the Kfexo(-) complex adopts a mix of the major and minor groove conformers with minimal effect upon the addition of non-hydrolysable nucleotides. For pol β, the insertion of dCTP was preferred opposite the dG-FAF adduct in a single nucleotide gap assay consistent with (19)F NMR data. Surface plasmon resonance binding kinetics revealed that pol β binds tightly with DNA in the presence of correct dCTP, but the adduct weakens binding with no nucleotide specificity. These results provide molecular insights into the DNA binding characteristics of FAF in the active site of DNA polymerases and the role of DNA structure and sequence on its coding potential.
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Affiliation(s)
- Vaidyanathan G Vaidyanathan
- Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy, University of Rhode Island, Kingston, Rhode Island 02881, USA
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50
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Olsen TJ, Choi Y, Sims PC, Gul OT, Corso BL, Dong C, Brown WA, Collins PG, Weiss GA. Electronic measurements of single-molecule processing by DNA polymerase I (Klenow fragment). J Am Chem Soc 2013; 135:7855-60. [PMID: 23631761 DOI: 10.1021/ja311603r] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Bioconjugating single molecules of the Klenow fragment of DNA polymerase I into electronic nanocircuits allowed electrical recordings of enzymatic function and dynamic variability with the resolution of individual nucleotide incorporation events. Continuous recordings of DNA polymerase processing multiple homopolymeric DNA templates extended over 600 s and through >10,000 bond-forming events. An enzymatic processivity of 42 nucleotides for a template of the same length was directly observed. Statistical analysis determined key kinetic parameters for the enzyme's open and closed conformations. Consistent with these nanocircuit-based observations, the enzyme's closed complex forms a phosphodiester bond in a highly efficient process >99.8% of the time, with a mean duration of only 0.3 ms for all four dNTPs. The rate-limiting step for catalysis occurs during the enzyme's open state, but with a nearly 2-fold longer duration for dATP or dTTP incorporation than for dCTP or dGTP into complementary, homopolymeric DNA templates. Taken together, the results provide a wealth of new information complementing prior work on the mechanism and dynamics of DNA polymerase I.
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Affiliation(s)
- Tivoli J Olsen
- Department of Chemistry, University of California, Irvine, California 92697, USA
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