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Thompson MK, Sharma N, Thorn A, Prakash A. Deciphering the crystal structure of a novel nanobody against the NEIL1 DNA glycosylase. Acta Crystallogr D Struct Biol 2024; 80:137-146. [PMID: 38289715 PMCID: PMC10836396 DOI: 10.1107/s205979832400038x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2023] [Accepted: 01/10/2024] [Indexed: 02/01/2024] Open
Abstract
Nanobodies (VHHs) are single-domain antibodies with three antigenic CDR regions and are used in diverse scientific applications. Here, an ∼14 kDa nanobody (A5) specific for the endonuclease VIII (Nei)-like 1 or NEIL1 DNA glycosylase involved in the first step of the base-excision repair pathway was crystallized and its structure was determined to 2.1 Å resolution. The crystals posed challenges due to potential twinning and anisotropic diffraction. Despite inconclusive twinning indicators, reprocessing in an orthorhombic setting and molecular replacement in space group P21212 enabled the successful modeling of 96% of residues in the asymmetric unit, with final Rwork and Rfree values of 0.199 and 0.229, respectively.
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Affiliation(s)
- Marlo K Thompson
- Mitchell Cancer Institute, University of South Alabama Health, 1660 Springhill Avenue, Mobile, AL 36604, USA
| | - Nidhi Sharma
- Mitchell Cancer Institute, University of South Alabama Health, 1660 Springhill Avenue, Mobile, AL 36604, USA
| | - Andrea Thorn
- Institut für Nanostruktur und Festkörperphysik, Universität Hamburg, Hamburg, Germany
| | - Aishwarya Prakash
- Mitchell Cancer Institute, University of South Alabama Health, 1660 Springhill Avenue, Mobile, AL 36604, USA
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Zuckerman JT, Minko IG, Kant M, Jaruga P, Stone MP, Dizdaroglu M, McCullough AK, Lloyd RS. Functional analyses of single nucleotide polymorphic variants of the DNA glycosylase NEIL1 in sub-Saharan African populations. DNA Repair (Amst) 2023; 129:103544. [PMID: 37517321 PMCID: PMC10546947 DOI: 10.1016/j.dnarep.2023.103544] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Revised: 07/07/2023] [Accepted: 07/18/2023] [Indexed: 08/01/2023]
Abstract
Nei-like glycosylase 1 (NEIL1) is a DNA repair enzyme that initiates the base excision repair (BER) pathway to cleanse the human genome of damage. The substrate specificity of NEIL1 includes several common base modifications formed under oxidative stress conditions, as well as the imidazole ring open adducts that are induced by alkylating agents following initial modification at N7 guanine. An example of the latter is the persistent and mutagenic 8,9-dihydro-8-(2,6-diamino-4-oxo-3,4-dihydropyrimid-5-yl-formamido)-9-hydroxyaflatoxin B1 (AFB1-FapyGua) adduct, resulting from the alkylating agent aflatoxin B1 (AFB1) exo-8-9-epoxide. Naturally occurring single nucleotide polymorphic (SNP) variants of NEIL1 are hypothesized to be associated with an increased risk for development of early-onset hepatocellular carcinoma (HCC), especially in environments with high exposures to aflatoxins and chronic inflammation from viral infections and alcohol consumption. Given that AFB1 exposures and hepatitis B viral (HBV) infections represent a major problem in the developing countries of sub-Saharan Africa, it is pertinent to study SNP NEIL1 variants that are present in this geographic region. In this investigation, we characterized the three most common NEIL1 variants found in this region: P321A, R323G, and I182M. Biochemical analyses were conducted to determine the proficiencies of these variants in initiating the repair of DNA lesions. Our data show that damage recognition and excision activities of P321A and R323G were near that of wild-type (WT) NEIL1 for both thymine glycol (ThyGly) and AFB1-FapyGua. The substrate specificities of these variants with respect to various oxidatively-induced base lesions were also similar to that of WT. In contrast, the I182M variant was unstable, such that it precipitated under a variety of conditions and underwent rapid inactivation at a biologically relevant temperature, with partial stabilization being observed in the presence of undamaged DNA. This study provides insight regarding the potential increased risk for early-onset HCC in human populations carrying the NEIL1 I182M variant.
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Affiliation(s)
- Jamie T Zuckerman
- Oregon Institute of Occupational Health Sciences, Oregon Health & Science University, Portland, OR 97239, United States
| | - Irina G Minko
- Oregon Institute of Occupational Health Sciences, Oregon Health & Science University, Portland, OR 97239, United States
| | - Melis Kant
- Biomolecular Measurement Division, National Institute of Standards and Technology, Gaithersburg, MD 20899, United States
| | - Pawel Jaruga
- Biomolecular Measurement Division, National Institute of Standards and Technology, Gaithersburg, MD 20899, United States
| | - Michael P Stone
- Department of Chemistry, Vanderbilt University, Nashville, TN 37240, United States
| | - Miral Dizdaroglu
- Biomolecular Measurement Division, National Institute of Standards and Technology, Gaithersburg, MD 20899, United States
| | - Amanda K McCullough
- Oregon Institute of Occupational Health Sciences, Oregon Health & Science University, Portland, OR 97239, United States; Department of Molecular and Medical Genetics, Oregon Health & Science University, Portland, OR 97239, United States
| | - R Stephen Lloyd
- Oregon Institute of Occupational Health Sciences, Oregon Health & Science University, Portland, OR 97239, United States; Department of Molecular and Medical Genetics, Oregon Health & Science University, Portland, OR 97239, United States.
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Lotsof ER, Krajewski AE, Anderson-Steele B, Rogers J, Zhang L, Yeo J, Conlon SG, Manlove AH, Lee JK, David SS. NEIL1 Recoding due to RNA Editing Impacts Lesion-Specific Recognition and Excision. J Am Chem Soc 2022; 144:14578-14589. [PMID: 35917336 DOI: 10.1021/jacs.2c03625] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A-to-I RNA editing is widespread in human cells but is uncommon in the coding regions of proteins outside the nervous system. An unusual target for recoding by the adenosine deaminase ADAR1 is the pre-mRNA of the base excision DNA repair enzyme NEIL1 that results in the conversion of a lysine (K) to arginine (R) within the lesion recognition loop and alters substrate specificity. Differences in base removal by unedited (UE, K242) vs edited (Ed, R242) NEIL1 were evaluated using a series of oxidatively modified DNA bases to provide insight into the chemical and structural features of the lesion base that impact isoform-specific repair. We find that UE NEIL1 exhibits higher activity than Ed NEIL1 toward the removal of oxidized pyrimidines, such as thymine glycol, uracil glycol, 5-hydroxyuracil, and 5-hydroxymethyluracil. Gas-phase calculations indicate that the relative rates in excision track with the more stable lactim tautomer and the proton affinity of N3 of the base lesion. These trends support the contribution of tautomerization and N3 protonation in NEIL1 excision catalysis of these pyrimidine base lesions. Structurally similar but distinct substrate lesions, 5-hydroxycytosine and guanidinohydantoin, are more efficiently removed by the Ed NEIL1 isoform, consistent with the inherent differences in tautomerization, proton affinities, and lability. We also observed biphasic kinetic profiles and lack of complete base removal with specific combinations of the lesion and NEIL1 isoform, suggestive of multiple lesion binding modes. The complexity of NEIL1 isoform activity implies multiple roles for NEIL1 in safeguarding accurate repair and as an epigenetic regulator.
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Affiliation(s)
- Elizabeth R Lotsof
- Department of Chemistry, University of California, Davis, Davis, California 95616, United States
| | - Allison E Krajewski
- Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, New Brunswick, New Jersey 08854, United States
| | - Brittany Anderson-Steele
- Department of Chemistry, University of California, Davis, Davis, California 95616, United States
| | - JohnPatrick Rogers
- Department of Chemistry, University of California, Davis, Davis, California 95616, United States
| | - Lanxin Zhang
- Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, New Brunswick, New Jersey 08854, United States
| | - Jongchan Yeo
- Department of Chemistry, University of California, Davis, Davis, California 95616, United States
| | - Savannah G Conlon
- Department of Chemistry, University of California, Davis, Davis, California 95616, United States
| | - Amelia H Manlove
- Department of Chemistry, University of California, Davis, Davis, California 95616, United States
| | - Jeehiun K Lee
- Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, New Brunswick, New Jersey 08854, United States
| | - Sheila S David
- Department of Chemistry, University of California, Davis, Davis, California 95616, United States
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Sharma N, Thompson MK, Arrington JF, Terry DM, Chakravarthy S, Prevelige PE, Prakash A. Novel interaction interfaces mediate the interaction between the NEIL1 DNA glycosylase and mitochondrial transcription factor A. Front Cell Dev Biol 2022; 10:893806. [PMID: 35938152 PMCID: PMC9354671 DOI: 10.3389/fcell.2022.893806] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Accepted: 07/01/2022] [Indexed: 02/01/2023] Open
Abstract
The maintenance of human mitochondrial DNA (mtDNA) is critical for proper cellular function as damage to mtDNA, if left unrepaired, can lead to a diverse array of pathologies. Of the pathways identified to participate in DNA repair within the mitochondria, base excision repair (BER) is the most extensively studied. Protein-protein interactions drive the step-by-step coordination required for the successful completion of this pathway and are important for crosstalk with other mitochondrial factors involved in genome maintenance. Human NEIL1 is one of seven DNA glycosylases that initiates BER in both the nuclear and mitochondrial compartments. In the current work, we scrutinized the interaction between NEIL1 and mitochondrial transcription factor A (TFAM), a protein that is essential for various aspects of mtDNA metabolism. We note, for the first time, that both the N- and C- terminal domains of NEIL1 interact with TFAM revealing a unique NEIL1 protein-binding interface. The interaction between the two proteins, as observed biochemically, appears to be transient and is most apparent at concentrations of low salt. The presence of DNA (or RNA) also positively influences the interaction between the two proteins, and molar mass estimates indicate that duplex DNA is required for complex formation at higher salt concentrations. Hydrogen deuterium exchange mass spectrometry data reveal that both proteins exchange less deuterium upon DNA binding, indicative of an interaction, and the addition of NEIL1 to the TFAM-DNA complex alters the interaction landscape. The transcriptional activity of TFAM appears to be independent of NEIL1 expression under normal cellular conditions, however, in the presence of DNA damage, we observe a significant reduction in the mRNA expression of TFAM-transcribed mitochondrial genes in the absence of NEIL1. Overall, our data indicate that the interaction between NEIL1 and TFAM can be modulated by local environment such as salt concentrations, protein availability, the presence of nucleic acids, as well as the presence of DNA damage.
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Affiliation(s)
- Nidhi Sharma
- Department of Biochemistry and Molecular Biology, Mitchell Cancer Institute, University of South Alabama, Mobile, AL, United States
| | - Marlo K. Thompson
- Department of Biochemistry and Molecular Biology, Mitchell Cancer Institute, University of South Alabama, Mobile, AL, United States
| | - Jennifer F. Arrington
- Department of Biochemistry and Molecular Biology, Mitchell Cancer Institute, University of South Alabama, Mobile, AL, United States
| | - Dava M. Terry
- Department of Biochemistry and Molecular Biology, Mitchell Cancer Institute, University of South Alabama, Mobile, AL, United States
| | - Srinivas Chakravarthy
- Advanced Photon Source, Illinois Institute of Technology, Chicago, IL, United States
| | - Peter E. Prevelige
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Aishwarya Prakash
- Department of Biochemistry and Molecular Biology, Mitchell Cancer Institute, University of South Alabama, Mobile, AL, United States
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Zhdanova PV, Ishchenko AA, Chernonosov AA, Zharkov DO, Koval VV. Dynamics and Conformational Changes in Human NEIL2 DNA Glycosylase Analyzed by Hydrogen/Deuterium Exchange Mass Spectrometry. J Mol Biol 2021; 434:167334. [PMID: 34757057 DOI: 10.1016/j.jmb.2021.167334] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Revised: 10/18/2021] [Accepted: 10/25/2021] [Indexed: 12/31/2022]
Abstract
Base excision DNA repair (BER) is necessary for removal of damaged nucleobases from the genome and their replacement with normal nucleobases. BER is initiated by DNA glycosylases, the enzymes that cleave the N-glycosidic bonds of damaged deoxynucleotides. Human endonuclease VIII-like protein 2 (hNEIL2), belonging to the helix-two-turn-helix structural superfamily of DNA glycosylases, is an enzyme uniquely specific for oxidized pyrimidines in non-canonical DNA substrates such as bubbles and loops. The structure of hNEIL2 has not been solved; its closest homologs with known structures are NEIL2 from opossum and from giant mimivirus. Here we analyze the conformational dynamics of free hNEIL2 using a combination of hydrogen/deuterium exchange mass spectrometry, homology modeling and molecular dynamics simulations. We show that a prominent feature of vertebrate NEIL2 - a large insert in its N-terminal domain absent from other DNA glycosylases - is unstructured in solution. It was suggested that helix-two-turn-helix DNA glycosylases undergo open-close transition upon DNA binding, with the large movement of their N- and C-terminal domains, but the open conformation has been elusive to capture. Our data point to the open conformation as favorable for free hNEIL2 in solution. Overall, our results are consistent with the view of hNEIL2 as a conformationally flexible protein, which may be due to its participation in the repair of non-canonical DNA structures and/or to the involvement in functional and regulatory protein-protein interactions.
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Affiliation(s)
- Polina V Zhdanova
- Institute of Chemical Biology and Fundamental Medicine SB RAS, Novosibisk, Russia; Novosibirsk State University, Novosibisk, Russia
| | - Alexander A Ishchenko
- Groupe "Réparation de lADN", Equipe Labellisée par la Ligue Nationale contre le Cancer, CNRS UMR 8200, Univ. Paris-Sud, Université Paris-Saclay, Villejuif F-94805, France; Gustave Roussy, Université Paris-Saclay, Villejuif F-94805, France
| | | | - Dmitry O Zharkov
- Institute of Chemical Biology and Fundamental Medicine SB RAS, Novosibisk, Russia; Novosibirsk State University, Novosibisk, Russia
| | - Vladimir V Koval
- Institute of Chemical Biology and Fundamental Medicine SB RAS, Novosibisk, Russia; Novosibirsk State University, Novosibisk, Russia.
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