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Ibrahim M, Wenzel C, Lallemang M, Balzer BN, Schwierz N. Adsorbing DNA to Mica by Cations: Influence of Valency and Ion Type. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:15553-15562. [PMID: 37877163 DOI: 10.1021/acs.langmuir.3c01835] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/26/2023]
Abstract
Ion-mediated attraction between DNA and mica plays a crucial role in biotechnological applications and molecular imaging. Here, we combine molecular dynamics simulations and single-molecule atomic force microscopy experiments to characterize the detachment forces of single-stranded DNA at mica surfaces mediated by the metal cations Li+, Na+, K+, Cs+, Mg2+, and Ca2+. Ion-specific adsorption at the mica/water interface compensates (Li+ and Na+) or overcompensates (K+, Cs+, Mg2+, and Ca2+) the bare negative surface charge of mica. In addition, direct and water-mediated contacts are formed between the ions, the phosphate oxygens of DNA, and mica. The different contact types give rise to low- and high-force pathways and a broad distribution of detachment forces. Weakly hydrated ions, such as Cs+ and water-mediated contacts, lead to low detachment forces and high mobility of the DNA on the surface. Direct ion-DNA or ion-surface contacts lead to significantly higher forces. The comprehensive view gained from our combined approach allows us to highlight the most promising cations for imaging in physiological conditions: K+, which overcompensates the negative mica charge and induces long-ranged attractions. Mg2+ and Ca2+, which form a few specific and long-lived contacts to bind DNA with high affinity.
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Affiliation(s)
- Mohd Ibrahim
- Institute of Physics, University of Augsburg, Universitätsstraße 1, 86159 Augsburg, Germany
- Department of Theoretical Biophysics, Max Planck Institute of Biophysics, Max-von-Laue-Straße 3, 60438 Frankfurt am Main, Germany
| | - Christiane Wenzel
- Institute of Physical Chemistry, University of Freiburg, Albertstraße 21, 79104 Freiburg, Germany
- Cluster of Excellence livMatS @ FIT-Freiburg Center for Interactive Materials and Bioinspired Technologies, University of Freiburg, Georges-Köhler-Allee 105, 79110 Freiburg, Germany
| | - Max Lallemang
- Institute of Physical Chemistry, University of Freiburg, Albertstraße 21, 79104 Freiburg, Germany
- Cluster of Excellence livMatS @ FIT-Freiburg Center for Interactive Materials and Bioinspired Technologies, University of Freiburg, Georges-Köhler-Allee 105, 79110 Freiburg, Germany
| | - Bizan N Balzer
- Institute of Physical Chemistry, University of Freiburg, Albertstraße 21, 79104 Freiburg, Germany
- Cluster of Excellence livMatS @ FIT-Freiburg Center for Interactive Materials and Bioinspired Technologies, University of Freiburg, Georges-Köhler-Allee 105, 79110 Freiburg, Germany
- Freiburg Materials Research Center (FMF), University of Freiburg, Stefan-Meier-Str. 21, 79104 Freiburg, Germany
| | - Nadine Schwierz
- Institute of Physics, University of Augsburg, Universitätsstraße 1, 86159 Augsburg, Germany
- Department of Theoretical Biophysics, Max Planck Institute of Biophysics, Max-von-Laue-Straße 3, 60438 Frankfurt am Main, Germany
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2
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Liu Y, Lan W, Wang C, Cao C. Two different kinds of interaction modes of deaminase APOBEC3A with single-stranded DNA in solution detected by nuclear magnetic resonance. Protein Sci 2022; 31:443-453. [PMID: 34792260 PMCID: PMC8819843 DOI: 10.1002/pro.4242] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Revised: 11/09/2021] [Accepted: 11/09/2021] [Indexed: 02/03/2023]
Abstract
APOBEC3A (A3A) deaminates deoxycytidine in target motif TC in a single-stranded DNA (we termed it as TC DNA), which mortally mutates viral pathogens and immunoglobulins, and leads to the diversification and lethality of cancers. The crystal structure of A3A-DNA revealed a unique U-shaped recognition mode of target base dC0 . However, when TC DNA was titrated into 15 N-labeled A3A solution, we observed two sets of 1 H-15 N cross-peaks of A3A in HSQC spectra, and two sets of 1 H-1 H cross-peaks of DNA in two-dimensional 13 C,15 N-filtered TOCSY spectra, indicating two different kinds of conformers of either A3A or TC DNA existing in solution. Here, mainly by NMR, we demonstrated that one DNA conformer interacted with one A3A conformer, forming a specific complex A3AS -DNAS in a way almost similar to that observed in the reported crystal A3A-DNA structure, where dC0 inserted into zinc ion binding center. While the other DNA conformer bound with another A3A conformer, but dC0 did not extend into the zinc-binding pocket, forming a nonspecific A3ANS -DNANS complex. The NMR solution structure implied three sites Asn61 , His182 and Arg189 were necessary to DNA recognition. These observations indicate a distinctive way from that reported in X-ray crystal structure, suggesting an unexpected mode of deaminase APOBEC3A to identify target motif TC in DNA in solution.
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Affiliation(s)
- Yaping Liu
- State Key Laboratory of Bioorganic and Natural Product ChemistryCenter for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, Chinese Academy of SciencesShanghaiChina,University of Chinese Academy of ScienceBeijingChina
| | - Wenxian Lan
- State Key Laboratory of Bioorganic and Natural Product ChemistryCenter for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, Chinese Academy of SciencesShanghaiChina
| | - Chunxi Wang
- State Key Laboratory of Bioorganic and Natural Product ChemistryCenter for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, Chinese Academy of SciencesShanghaiChina
| | - Chunyang Cao
- State Key Laboratory of Bioorganic and Natural Product ChemistryCenter for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, Chinese Academy of SciencesShanghaiChina,University of Chinese Academy of ScienceBeijingChina
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3
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Pan Y, Banerjee S, Zagorski K, Shlyakhtenko LS, Kolomeisky AB, Lyubchenko YL. Molecular Model for the Surface-Catalyzed Protein Self-Assembly. J Phys Chem B 2020; 124:366-372. [PMID: 31867969 DOI: 10.1021/acs.jpcb.9b10052] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The importance of cell surfaces in the self-assembly of proteins is widely accepted. One biologically significant event is the assembly of amyloidogenic proteins into aggregates, which leads to neurodegenerative disorders like Alzheimer's and Parkinson's diseases. The interaction of amyloidogenic proteins with cellular membranes appears to dramatically facilitate the aggregation process. Recent findings indicate that, in the presence of surfaces, aggregation occurs at physiologically low concentrations, suggesting that interaction with surfaces plays a critical role in the disease-prone aggregation process. However, the molecular mechanisms behind the on-surface aggregation process remain unclear. Here, we provide a theoretical model that offers a molecular explanation. According to this model, monomers transiently immobilized to surfaces increase the local monomer protein concentration and thus work as nuclei to dramatically accelerate the entire aggregation process. This physical-chemical theory was verified by experimental studies, using mica surfaces, to examine the aggregation kinetics of amyloidogenic α-synuclein protein and non-amyloidogenic cytosine deaminase APOBEC3G.
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Affiliation(s)
- Yangang Pan
- Department of Pharmaceutical Sciences, College of Pharmacy , University of Nebraska Medical Center , 986025 Nebraska Medical Center, Omaha , Nebraska 68198-6025 , United States
| | - Siddhartha Banerjee
- Department of Pharmaceutical Sciences, College of Pharmacy , University of Nebraska Medical Center , 986025 Nebraska Medical Center, Omaha , Nebraska 68198-6025 , United States
| | - Karen Zagorski
- Department of Pharmaceutical Sciences, College of Pharmacy , University of Nebraska Medical Center , 986025 Nebraska Medical Center, Omaha , Nebraska 68198-6025 , United States
| | - Luda S Shlyakhtenko
- Department of Pharmaceutical Sciences, College of Pharmacy , University of Nebraska Medical Center , 986025 Nebraska Medical Center, Omaha , Nebraska 68198-6025 , United States
| | - Anatoly B Kolomeisky
- Department of Chemistry-MS 60 , Rice University , 6100 Main Street , Houston , Texas 77005-1892 , Unites States
| | - Yuri L Lyubchenko
- Department of Pharmaceutical Sciences, College of Pharmacy , University of Nebraska Medical Center , 986025 Nebraska Medical Center, Omaha , Nebraska 68198-6025 , United States
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4
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Morse M, Naufer MN, Feng Y, Chelico L, Rouzina I, Williams MC. HIV restriction factor APOBEC3G binds in multiple steps and conformations to search and deaminate single-stranded DNA. eLife 2019; 8:e52649. [PMID: 31850845 PMCID: PMC6946564 DOI: 10.7554/elife.52649] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2019] [Accepted: 12/18/2019] [Indexed: 12/15/2022] Open
Abstract
APOBEC3G (A3G), an enzyme expressed in primates with the potential to inhibit human immunodeficiency virus type 1 (HIV-1) infectivity, is a single-stranded DNA (ssDNA) deoxycytidine deaminase with two domains, a catalytically active, weakly ssDNA binding C-terminal domain (CTD) and a catalytically inactive, strongly ssDNA binding N-terminal domain (NTD). Using optical tweezers, we measure A3G binding a single, long ssDNA substrate under various applied forces to characterize the binding interaction. A3G binds ssDNA in multiple steps and in two distinct conformations, distinguished by degree of ssDNA contraction. A3G stabilizes formation of ssDNA loops, an ability inhibited by A3G oligomerization. Our data suggests A3G securely binds ssDNA through the NTD, while the CTD samples and potentially deaminates the substrate. Oligomerization of A3G stabilizes ssDNA binding but inhibits the CTD's search function. These processes explain A3G's ability to efficiently deaminate numerous sites across a 10,000 base viral genome during the reverse transcription process.
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Affiliation(s)
- Michael Morse
- Department of PhysicsNortheastern UniversityBostonUnited States
| | - M Nabuan Naufer
- Department of PhysicsNortheastern UniversityBostonUnited States
| | - Yuqing Feng
- Department of Biochemistry, Microbiology and ImmunologyUniversity of SaskatchewanSaskatoonCanada
| | - Linda Chelico
- Department of Biochemistry, Microbiology and ImmunologyUniversity of SaskatchewanSaskatoonCanada
| | - Ioulia Rouzina
- Department of Chemistry and BiochemistryOhio State UniversityColumbusUnited States
| | - Mark C Williams
- Department of PhysicsNortheastern UniversityBostonUnited States
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Stumme-Diers MP, Stormberg T, Sun Z, Lyubchenko YL. Probing The Structure And Dynamics Of Nucleosomes Using Atomic Force Microscopy Imaging. J Vis Exp 2019. [PMID: 30774135 DOI: 10.3791/58820] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Chromatin, which is a long chain of nucleosome subunits, is a dynamic system that allows for such critical processes as DNA replication and transcription to take place in eukaryotic cells. The dynamics of nucleosomes provides access to the DNA by replication and transcription machineries, and critically contributes to the molecular mechanisms underlying chromatin functions. Single-molecule studies such as atomic force microscopy (AFM) imaging have contributed significantly to our current understanding of the role of nucleosome structure and dynamics. The current protocol describes the steps enabling high-resolution AFM imaging techniques to study the structural and dynamic properties of nucleosomes. The protocol is illustrated by AFM data obtained for the centromere nucleosomes in which H3 histone is replaced with its counterpart centromere protein A (CENP-A). The protocol starts with the assembly of mono-nucleosomes using a continuous dilution method. The preparation of the mica substrate functionalized with aminopropyl silatrane (APS-mica) that is used for the nucleosome imaging is critical for the AFM visualization of nucleosomes described and the procedure to prepare the substrate is provided. Nucleosomes deposited on the APS-mica surface are first imaged using static AFM, which captures a snapshot of the nucleosome population. From analyses of these images, such parameters as the size of DNA wrapped around the nucleosomes can be measured and this process is also detailed. The time-lapse AFM imaging procedure in the liquid is described for the high-speed time-lapse AFM that can capture several frames of nucleosome dynamics per second. Finally, the analysis of nucleosome dynamics enabling the quantitative characterization of the dynamic processes is described and illustrated.
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Affiliation(s)
| | - Tommy Stormberg
- Department of Pharmaceutical Sciences, University of Nebraska Medical Center
| | - Zhiqiang Sun
- Department of Pharmaceutical Sciences, University of Nebraska Medical Center
| | - Yuri L Lyubchenko
- Department of Pharmaceutical Sciences, University of Nebraska Medical Center;
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Calcium increases titin N2A binding to F-actin and regulated thin filaments. Sci Rep 2018; 8:14575. [PMID: 30275509 PMCID: PMC6167357 DOI: 10.1038/s41598-018-32952-8] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Accepted: 09/19/2018] [Indexed: 12/30/2022] Open
Abstract
Mutations in titin are responsible for many cardiac and muscle diseases, yet the underlying mechanisms remain largely unexplained. Numerous studies have established roles for titin in muscle function, and Ca2+-dependent interactions between titin and actin have been suggested to play a role in muscle contraction. The present study used co-sedimentation assays, dynamic force spectroscopy (DFS), and in vitro motility (IVM) assays to determine whether the N2A region of titin, overlooked in previous studies, interacts with actin in the presence of Ca2+. Co-sedimentation demonstrated that N2A – F-actin binding increases with increasing protein and Ca2+ concentration, DFS demonstrated increased rupture forces and decreased koff in the presence of Ca2+, and IVM demonstrated a Ca2+-dependent reduction in motility of F-actin and reconstituted thin filaments in the presence of N2A. These results indicate that Ca2+ increases the strength and stability of N2A – actin interactions, supporting the hypothesis that titin plays a regulatory role in muscle contraction. The results further support a model in which N2A – actin binding in active muscle increases titin stiffness, and that impairment of this mechanism contributes to the phenotype in muscular dystrophy with myositis. Future studies are required to determine whether titin – actin binding occurs in skeletal muscle sarcomeres in vivo.
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7
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Salter JD, Smith HC. Modeling the Embrace of a Mutator: APOBEC Selection of Nucleic Acid Ligands. Trends Biochem Sci 2018; 43:606-622. [PMID: 29803538 PMCID: PMC6073885 DOI: 10.1016/j.tibs.2018.04.013] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Revised: 04/25/2018] [Accepted: 04/30/2018] [Indexed: 12/17/2022]
Abstract
The 11-member APOBEC (apolipoprotein B mRNA editing catalytic polypeptide-like) family of zinc-dependent cytidine deaminases bind to RNA and single-stranded DNA (ssDNA) and, in specific contexts, modify select (deoxy)cytidines to (deoxy)uridines. In this review, we describe advances made through high-resolution co-crystal structures of APOBECs bound to mono- or oligonucleotides that reveal potential substrate-specific binding sites at the active site and non-sequence-specific nucleic acid binding sites distal to the active site. We also discuss the effect of APOBEC oligomerization on functionality. Future structural studies will need to address how ssDNA binding away from the active site may enhance catalysis and the mechanism by which RNA binding may modulate catalytic activity on ssDNA. APOBEC proteins catalyze deamination of cytidine or deoxycytidine in either a sequence-specific or semi-specific manner on either DNA or RNA. APOBECs each possess the cytidine deaminase core fold, but sequence and structural differences among loops surrounding the zinc-dependent active site impart differences in sequence-dependent target preferences, binding affinity, catalytic rate, and regulation of substrate access to the active site among the 11 family members. APOBECs also regulate the deamination reaction through additional nucleic acid substrate binding sites located within surface grooves or patches of positive electrostatic potential that are distal to the active site but may do so nonspecifically. Binding of nonsubstrate RNA and RNA-mediated oligomerization by APOBECs that deaminate ssDNA downregulates catalytic activity but also controls APOBEC subcellular or virion localization. The presence of a second, though noncatalytic, cytidine deaminase domain for some APOBECs and the ability of some APOBECs to oligomerize add additional molecular surfaces for positive or negative regulation of catalysis through nucleic acid binding.
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Affiliation(s)
- Jason D Salter
- OyaGen, Inc., 77 Ridgeland Road, Rochester, NY 14623, USA.
| | - Harold C Smith
- OyaGen, Inc., 77 Ridgeland Road, Rochester, NY 14623, USA; University of Rochester, School of Medicine and Dentistry, Department of Biochemistry and Biophysics, 601 Elmwood Avenue, Rochester, NY 14642, USA.
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8
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Adolph MB, Love RP, Feng Y, Chelico L. Enzyme cycling contributes to efficient induction of genome mutagenesis by the cytidine deaminase APOBEC3B. Nucleic Acids Res 2017; 45:11925-11940. [PMID: 28981865 PMCID: PMC5714209 DOI: 10.1093/nar/gkx832] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2017] [Accepted: 09/11/2017] [Indexed: 02/06/2023] Open
Abstract
The single-stranded DNA cytidine deaminases APOBEC3B, APOBEC3H haplotype I, and APOBEC3A can contribute to cancer through deamination of cytosine to form promutagenic uracil in genomic DNA. The enzymes must access single-stranded DNA during the dynamic processes of DNA replication or transcription, but the enzymatic mechanisms enabling this activity are not known. To study this, we developed a method to purify full length APOBEC3B and characterized it in comparison to APOBEC3A and APOBEC3H on substrates relevant to cancer mutagenesis. We found that the ability of an APOBEC3 to cycle between DNA substrates determined whether it was able to efficiently deaminate single-stranded DNA produced by replication and single-stranded DNA bound by replication protein A (RPA). APOBEC3 deaminase activity during transcription had a size limitation that inhibited APOBEC3B tetramers, but not APOBEC3A monomers or APOBEC3H dimers. Altogether, the data support a model in which the availability of single-stranded DNA is necessary, but alone not sufficient for APOBEC3-induced mutagenesis in cells because there is also a dependence on the inherent biochemical properties of the enzymes. The biochemical properties identified in this study can be used to measure the mutagenic potential of other APOBEC enzymes in the genome.
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Affiliation(s)
- Madison B Adolph
- Department of Microbiology and Immunology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Robin P Love
- Department of Microbiology and Immunology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Yuqing Feng
- Department of Microbiology and Immunology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Linda Chelico
- Department of Microbiology and Immunology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
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Dimerization regulates both deaminase-dependent and deaminase-independent HIV-1 restriction by APOBEC3G. Nat Commun 2017; 8:597. [PMID: 28928403 PMCID: PMC5605669 DOI: 10.1038/s41467-017-00501-y] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2017] [Accepted: 07/04/2017] [Indexed: 01/09/2023] Open
Abstract
APOBEC3G (A3G) is a human enzyme that inhibits human immunodeficiency virus type 1 (HIV-1) infectivity, in the absence of the viral infectivity factor Vif, through deoxycytidine deamination and a deamination-independent mechanism. A3G converts from a fast to a slow binding state through oligomerization, which suggests that large A3G oligomers could block HIV-1 reverse transcriptase-mediated DNA synthesis, thereby inhibiting HIV-1 replication. However, it is unclear how the small number of A3G molecules found in the virus could form large oligomers. Here we measure the single-stranded DNA binding and oligomerization kinetics of wild-type and oligomerization-deficient A3G, and find that A3G first transiently binds DNA as a monomer. Subsequently, A3G forms N-terminal domain-mediated dimers, whose dissociation from DNA is reduced and their deaminase activity inhibited. Overall, our results suggest that the A3G molecules packaged in the virion first deaminate viral DNA as monomers before dimerizing to form multiple enzymatically deficient roadblocks that may inhibit reverse transcription. APOBEC3G inhibits HIV-1 viral replication via catalytic and non-catalytic processes. Here the authors show that APOBEC3G binds single-stranded DNA as an active deaminase monomer, subsequently forming catalytic-inactive dimers that block reverse transcriptase-mediated DNA synthesis.
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10
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Anti-HIV Activities and Mechanism of 12-O-Tricosanoylphorbol-20-acetate, a Novel Phorbol Ester from Ostodes katharinae. Molecules 2017; 22:molecules22091498. [PMID: 28885587 PMCID: PMC6151696 DOI: 10.3390/molecules22091498] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2017] [Revised: 09/01/2017] [Accepted: 09/06/2017] [Indexed: 01/09/2023] Open
Abstract
APOBEC3G is a member of the human cytidine deaminase family that restricts Vif-deficient viruses by being packaged with progeny virions and inducing the G to A mutation during the synthesis of HIV-1 viral DNA when the progeny virus infects new cells. HIV-1 Vif protein resists the activity of A3G by mediating A3G degradation. Phorbol esters are plant-derived organic compounds belonging to the tigliane family of diterpenes and could activate the PKC pathway. In this study, we identified an inhibitor 12-O-tricosanoylphorbol-20-acetate (hop-8), a novel ester of phorbol which was isolated from Ostodes katharinae of the family Euphorbiaceae, that inhibited the replication of wild-type HIV-1 and HIV-2 strains and drug-resistant strains broadly both in C8166 cells and PBMCs with low cytotoxicity and the EC50 values ranged from 0.106 μM to 7.987 μM. One of the main mechanisms of hop-8 is to stimulate A3G expressing in HIV-1 producing cells and upregulate the A3G level in progeny virions, which results in reducing the infectivity of the progeny virus. This novel mechanism of hop-8 inhibition of HIV replication might represents a promising approach for developing new therapeutics for HIV infection.
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Pan Y, Sun Z, Maiti A, Kanai T, Matsuo H, Li M, Harris RS, Shlyakhtenko LS, Lyubchenko YL. Nanoscale Characterization of Interaction of APOBEC3G with RNA. Biochemistry 2017; 56:1473-1481. [PMID: 28029777 DOI: 10.1021/acs.biochem.6b01189] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The human cytidine deaminase APOBEC3G (A3G) is a potent inhibitor of the HIV-1 virus in the absence of viral infectivity factor (Vif). The molecular mechanism of A3G antiviral activity is primarily attributed to deamination of single-stranded DNA (ssDNA); however, the nondeamination mechanism also contributes to HIV-1 restriction. The interaction of A3G with ssDNA and RNA is required for its antiviral activity. Here we used atomic force microscopy to directly visualize A3G-RNA and A3G-ssDNA complexes and compare them to each other. Our results showed that A3G in A3G-RNA complexes exists primarily in monomeric-dimeric states, similar to its stoichiometry in complexes with ssDNA. New A3G-RNA complexes in which A3G binds to two RNA molecules were identified. These data suggest the existence of two separate RNA binding sites on A3G. Such complexes were not observed with ssDNA substrates. Time-lapse high-speed atomic force microscopy was applied to characterize the dynamics of the complexes. The data revealed that the two RNA binding sites have different affinities for A3G. On the basis of the obtained results, a model for the interaction of A3G with RNA is proposed.
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Affiliation(s)
- Yangang Pan
- Department of Pharmaceutical Sciences, College of Pharmacy, WSH, University of Nebraska Medical Center , 986025 Nebraska Medical Center, Omaha, Nebraska 68198-6025, United States
| | - Zhiqiang Sun
- Department of Pharmaceutical Sciences, College of Pharmacy, WSH, University of Nebraska Medical Center , 986025 Nebraska Medical Center, Omaha, Nebraska 68198-6025, United States
| | - Atanu Maiti
- Frederick National Laboratory for Cancer Research, Leidos Biomedical Research, Inc. , Advanced Technology Research Facility, 8560 Progress Drive, Frederick, Maryland 21702, United States
| | - Tapan Kanai
- Frederick National Laboratory for Cancer Research, Leidos Biomedical Research, Inc. , Advanced Technology Research Facility, 8560 Progress Drive, Frederick, Maryland 21702, United States
| | - Hiroshi Matsuo
- Frederick National Laboratory for Cancer Research, Leidos Biomedical Research, Inc. , Advanced Technology Research Facility, 8560 Progress Drive, Frederick, Maryland 21702, United States
| | - Ming Li
- Department of Biochemistry, Molecular Biology and Biophysics, Institute for Molecular Virology, Center for Genome Engineering, Masonic Cancer Center, University of Minnesota , Minneapolis, Minnesota 55455, United States
| | - Reuben S Harris
- Department of Biochemistry, Molecular Biology and Biophysics, Institute for Molecular Virology, Center for Genome Engineering, Masonic Cancer Center, University of Minnesota , Minneapolis, Minnesota 55455, United States.,Howard Hughes Medical Institute, University of Minnesota , Minneapolis, Minnesota 55455, United States
| | - Luda S Shlyakhtenko
- Department of Pharmaceutical Sciences, College of Pharmacy, WSH, University of Nebraska Medical Center , 986025 Nebraska Medical Center, Omaha, Nebraska 68198-6025, United States
| | - Yuri L Lyubchenko
- Department of Pharmaceutical Sciences, College of Pharmacy, WSH, University of Nebraska Medical Center , 986025 Nebraska Medical Center, Omaha, Nebraska 68198-6025, United States
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12
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Okada A, Iwatani Y. APOBEC3G-Mediated G-to-A Hypermutation of the HIV-1 Genome: The Missing Link in Antiviral Molecular Mechanisms. Front Microbiol 2016; 7:2027. [PMID: 28066353 PMCID: PMC5165236 DOI: 10.3389/fmicb.2016.02027] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2016] [Accepted: 12/02/2016] [Indexed: 12/20/2022] Open
Abstract
APOBEC3G (A3G) is a member of the cellular polynucleotide cytidine deaminases, which catalyze the deamination of cytosine (dC) to uracil (dU) in single-stranded DNA. These enzymes potently inhibit the replication of a variety of retroviruses and retrotransposons, including HIV-1. A3G is incorporated into vif-deficient HIV-1 virions and targets viral reverse transcripts, particularly minus-stranded DNA products, in newly infected cells. It is well established that the enzymatic activity of A3G is closely correlated with the potential to greatly inhibit HIV-1 replication in the absence of Vif. However, the details of the underlying molecular mechanisms are not fully understood. One potential mechanism of A3G antiviral activity is that the A3G-dependent deamination may trigger degradation of the dU-containing reverse transcripts by cellular uracil DNA glycosylases (UDGs). More recently, another mechanism has been suggested, in which the virion-incorporated A3G generates lethal levels of the G-to-A hypermutation in the viral DNA genome, thus potentially driving the viruses into “error catastrophe” mode. In this mini review article, we summarize the deaminase-dependent and deaminase-independent molecular mechanisms of A3G and discuss how A3G-mediated deamination is linked to antiviral mechanisms.
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Affiliation(s)
- Ayaka Okada
- Department of Microbiology and Immunology, Laboratory of Infectious Diseases, Clinical Research Center, National Hospital Organization Nagoya Medical Center Nagoya, Japan
| | - Yasumasa Iwatani
- Department of Microbiology and Immunology, Laboratory of Infectious Diseases, Clinical Research Center, National Hospital Organization Nagoya Medical CenterNagoya, Japan; Department of AIDS Research, Nagoya University Graduate School of MedicineNagoya, Japan
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13
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The APOBEC Protein Family: United by Structure, Divergent in Function. Trends Biochem Sci 2016; 41:578-594. [PMID: 27283515 DOI: 10.1016/j.tibs.2016.05.001] [Citation(s) in RCA: 235] [Impact Index Per Article: 29.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2016] [Revised: 04/28/2016] [Accepted: 05/03/2016] [Indexed: 12/13/2022]
Abstract
The APOBEC (apolipoprotein B mRNA editing catalytic polypeptide-like) family of proteins have diverse and important functions in human health and disease. These proteins have an intrinsic ability to bind to both RNA and single-stranded (ss) DNA. Both function and tissue-specific expression varies widely for each APOBEC protein. We are beginning to understand that the activity of APOBEC proteins is regulated through genetic alterations, changes in their transcription and mRNA processing, and through their interactions with other macromolecules in the cell. Loss of cellular control of APOBEC activities leads to DNA hypermutation and promiscuous RNA editing associated with the development of cancer or viral drug resistance, underscoring the importance of understanding how APOBEC proteins are regulated.
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Shlyakhtenko LS, Dutta S, Li M, Harris RS, Lyubchenko YL. Single-Molecule Force Spectroscopy Studies of APOBEC3A-Single-Stranded DNA Complexes. Biochemistry 2016; 55:3102-6. [PMID: 27182892 DOI: 10.1021/acs.biochem.6b00214] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
APOBEC3A (A3A) inhibits the replication of a range of viruses and transposons and might also play a role in carcinogenesis. It is a single-domain deaminase enzyme that interacts with single-stranded DNA (ssDNA) and converts cytidines to uridines within specific trinucleotide contexts. Although there is abundant information that describes the potential biological activities of A3A, the interplay between binding ssDNA and sequence-specific deaminase activity remains controversial. Using a single-molecule atomic force microscopy spectroscopy approach developed by Shlyakhtenko et al. [(2015) Sci. Rep. 5, 15648], we determine the stability of A3A in complex with different ssDNA sequences. We found that the strength of the complex is sequence-dependent, with more stable complexes formed with deaminase-specific sequences. A correlation between the deaminase activity of A3A and the complex strength was identified. The ssDNA binding properties of A3A and those for A3G are also compared and discussed.
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Affiliation(s)
- Luda S Shlyakhtenko
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Nebraska Medical Center , Omaha, Nebraska 68198-6000, United States
| | - Samrat Dutta
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Nebraska Medical Center , Omaha, Nebraska 68198-6000, United States
| | - Ming Li
- Department of Biochemistry, Molecular Biology, and Biophysics, Institute for Molecular Virology, Center for Genome Engineering, Masonic Cancer Center, University of Minnesota , Minneapolis, Minnesota 55455, United States
| | - Reuben S Harris
- Department of Biochemistry, Molecular Biology, and Biophysics, Institute for Molecular Virology, Center for Genome Engineering, Masonic Cancer Center, University of Minnesota , Minneapolis, Minnesota 55455, United States.,Howard Hughes Medical Institute, University of Minnesota , Minneapolis, Minnesota 55455, United States
| | - Yuri L Lyubchenko
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Nebraska Medical Center , Omaha, Nebraska 68198-6000, United States
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Xu F, Song H, Li N, Tan G. HBsAg blocks TYPE I IFN induced up-regulation of A3G through inhibition of STAT3. Biochem Biophys Res Commun 2016; 473:219-223. [PMID: 27003258 DOI: 10.1016/j.bbrc.2016.03.082] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2016] [Accepted: 03/18/2016] [Indexed: 02/06/2023]
Abstract
Interferon (IFN) is a regularly utilized therapeutic for the treatment of chronic hepatitis B and appears to induce superior HBeAg seroconversion comparing nucleos/tide analogs. However, the mechanisms underlying IFN inhibition of HBV replication, as well as poor responses to IFN are unclear. Apobec3G has been reported to be involved in regulating HBV replication. In this study, we investigated Apobec3G expression and regulatory pathways during HBV infection. We show that over-expression of A3G leads to inhibition of HBV replication. We also show that IFN induces a significant increase in A3G protein expression, which is associated with STAT3 activation. We further show that A3G expression in HBV patients is lower compared to non-infected controls, possibly by HBsAg which inhibits IFN induced A3G up-regulation in a dose dependent manner. This process is likely mediated through inhibition of STAT3-Ser727 phosphorylation. The results presented in this study indicate that STAT3 plays an important role in IFN-induced A3G production, and HBsAg may correlated with poor response to IFN treatment.
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Affiliation(s)
- Fengchao Xu
- Institute of Translational Medicine, Department of Immunology, The First Hospital, Jilin University, Changchun, Jilin, 130061, PR China
| | - Hongxiao Song
- Institute of Translational Medicine, Department of Immunology, The First Hospital, Jilin University, Changchun, Jilin, 130061, PR China
| | - Na Li
- Department of Obstetric, The First Hospital, Jilin University, Changchun, Jilin, 130021, PR China
| | - Guangyun Tan
- Institute of Translational Medicine, Department of Immunology, The First Hospital, Jilin University, Changchun, Jilin, 130061, PR China.
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Dutta S, Armitage BA, Lyubchenko YL. Probing of miniPEGγ-PNA-DNA Hybrid Duplex Stability with AFM Force Spectroscopy. Biochemistry 2016; 55:1523-8. [PMID: 26898903 DOI: 10.1021/acs.biochem.5b01250] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Peptide nucleic acids (PNA) are synthetic polymers, the neutral peptide backbone of which provides elevated stability to PNA-PNA and PNA-DNA hybrid duplexes. It was demonstrated that incorporation of diethylene glycol (miniPEG) at the γ position of the peptide backbone increased the thermal stability of the hybrid duplexes (Sahu, B. et al. J. Org. Chem. 2011, 76, 5614-5627). Here, we applied atomic force microscopy (AFM) based single molecule force spectroscopy and dynamic force spectroscopy (DFS) to test the strength and stability of the hybrid 10 bp duplex. This hybrid duplex consisted of miniPEGγ-PNA and DNA of the same length (γ(MP)PNA-DNA), which we compared to a DNA duplex with a homologous sequence. AFM force spectroscopy data obtained at the same conditions showed that the γ(MP)PNA-DNA hybrid is more stable than the DNA counterpart, 65 ± 15 pN vs 47 ± 15 pN, respectively. The DFS measurements performed in a range of pulling speeds analyzed in the framework of the Bell-Evans approach yielded a dissociation constant, koff ≈ 0.030 ± 0.01 s⁻¹ for γ(MP)PNA-DNA hybrid duplex vs 0.375 ± 0.18 s⁻¹ for the DNA-DNA duplex suggesting that the hybrid duplex is much more stable. Correlating the high affinity of γ(MP)PNA-DNA to slow dissociation kinetics is consistent with prior bulk characterization by surface plasmon resonance. Given the growing interest in γ(MP)PNA as well as other synthetic DNA analogues, the use of single molecule experiments along with computational analysis of force spectroscopy data will provide direct characterization of various modifications as well as higher order structures such as triplexes and quadruplexes.
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Affiliation(s)
- Samrat Dutta
- Department of Pharmaceutical Sciences, University of Nebraska Medical Center , Omaha, Nebraska, United States
| | - Bruce A Armitage
- Department of Chemistry and Center for Nucleic Acids Science and Technology, Carnegie Mellon University , Pittsburgh, Pennsylvania, United States
| | - Yuri L Lyubchenko
- Department of Pharmaceutical Sciences, University of Nebraska Medical Center , Omaha, Nebraska, United States
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