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Koirala RP, Adhikari NP. Base flipping mechanism and binding strength of methyl-damaged DNA during the interaction with AGT. J Biol Phys 2024; 50:71-87. [PMID: 38150168 DOI: 10.1007/s10867-023-09649-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Accepted: 11/21/2023] [Indexed: 12/28/2023] Open
Abstract
Methyl damage to DNA bases is common in the cell nucleus. O6-alkylguanine-DNA alkyl transferase (AGT) may be a promising candidate for direct damage reversal in methylated DNA (mDNA) at the O6 point of the guanine. Indeed, atomic-level investigations in the contact region of AGT-DNA complex can provide an in-depth understanding of their binding mechanism, allowing to evaluate the silico-drug nature of AGT and its utility in removing methyl damage in DNA. In this study, molecular dynamics (MD) simulation was utilized to examine the flipping of methylated nucleotide, the binding mechanism between mDNA and AGT, and the comparison of binding strength prior and post methyl transfer to AGT. The study reveals that methylation at the O6 atom of guanine weakens the hydrogen bond (H-bond) between guanine and cytosine, permitting for the flipping of such nucleotide. The formation of a H-bond between the base pair of methylated nucleotide (i.e., cytosine) and the intercalated arginine of AGT also forces the nucleotide to rotate. Following that, electrostatics and van der Waals contacts as well as hydrogen bonding contribute to form the complex of DNA and protein. The stronger binding of AGT with DNA before methyl transfer creates the suitable condition to transfer methyl adduct from DNA to AGT.
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Yin Y, Zhang L. Archaeal DNA alkylation repair conducted by DNA glycosylase and methyltransferase. Appl Microbiol Biotechnol 2023; 107:3131-3142. [PMID: 37036526 DOI: 10.1007/s00253-023-12506-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Revised: 03/25/2023] [Accepted: 03/28/2023] [Indexed: 04/11/2023]
Abstract
Alkylated bases in DNA created in the presence of endogenous and exogenous alkylating agents are either cytotoxic or mutagenic, or both to a cell. Currently, cells have evolved several strategies for repairing alkylated base. One strategy is a base excision repair process triggered by a specific DNA glycosylase that is used for the repair of the cytotoxic 3-methyladenine. Additionally, the cytotoxic and mutagenic O6-methylguanine (O6-meG) is corrected by O6-methylguanine methyltransferase (MGMT) via directly transferring the methyl group in the lesion to a specific cysteine in this protein. Furthermore, oxidative DNA demethylation catalyzed by DNA dioxygenase is utilized for repairing the cytotoxic 3-methylcytosine (3-meC) and 1-methyladenine (1-meA) in a direct reversal manner. As the third domain of life, Archaea possess 3-methyladenine DNA glycosylase II (AlkA) and MGMT, but no DNA dioxygenase homologue responsible for oxidative demethylation. Herein, we summarize recent progress in structural and biochemical properties of archaeal AlkA and MGMT to gain a better understanding of archaeal DNA alkylation repair, focusing on similarities and differences between the proteins from different archaeal species and between these archaeal proteins and their bacterial and eukaryotic relatives. To our knowledge, it is the first review on archaeal DNA alkylation repair conducted by DNA glycosylase and methyltransferase. KEY POINTS: • Archaeal MGMT plays an essential role in the repair of O 6 -meG • Archaeal AlkA can repair 3-meC and 1-meA.
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Affiliation(s)
- Youcheng Yin
- Marine Science & Technology Institute, College of Environmental Science and Engineering, Yangzhou University, Yangzhou City, China
| | - Likui Zhang
- Marine Science & Technology Institute, College of Environmental Science and Engineering, Yangzhou University, Yangzhou City, China.
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Monika, Sheetal, Thakur N, Chand Bhalla T. Biotransformation of 3-cyanopyridine to nicotinic acid using whole-cell nitrilase of Gordonia terrae mutant MN12. Bioprocess Biosyst Eng 2023; 46:195-206. [PMID: 36451047 DOI: 10.1007/s00449-022-02823-8] [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: 10/07/2022] [Accepted: 11/21/2022] [Indexed: 12/03/2022]
Abstract
In the present study, the Gordonia terrae was subjected to chemical mutagenesis using ethyl methane sulfonate (EMS) and methyl methane sulfonate (MMS), N-methyl-N-nitro-N-nitrosoguanidine (MNNG), 5-bromouracil (5-BU) and hydroxylamine with the aim of improving the catalytic efficiency of its nitrilase for conversion of 3-cyanopyridine to nicotinic acid. A mutant MN12 generated with MNNG exhibited increase in nitrilase activity from 0.5 U/mg dcw (dry cell weight) (in the wild G. terrae) to 1.33 U/mg dcw. Further optimizations of culture conditions using response surface methodology enhanced the enzyme production to 1.2-fold. Whole-cell catalysis was adopted for bench-scale synthesis of nicotinic acid, and 100% conversion of 100 mM 3-cyanopyridine was achieved in potassium phosphate buffer (0.1 M, pH 8.0) at 40 °C in 15 min. The whole-cell nitrilase of the mutant MN12 exhibited higher rate of product formation and volumetric productivity, i.e., 24.56 g/h/g dcw and 221 g/L as compared to 8.95 g/h/g dcw and 196.8 g/L of the wild G. terrae. The recovered product was confirmed by HPLC, FTIR and NMR analysis with high purity (> 99.9%). These results indicated that the mutant MN12 of G. terrae as whole-cell nitrilase is a very promising biocatalyst for the large-scale synthesis of nicotinic acid.
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Affiliation(s)
- Monika
- Department of Biotechnology, Himachal Pradesh University, Shimla, Himachal Pradesh, 171005, India
| | - Sheetal
- Department of Biotechnology, Himachal Pradesh University, Shimla, Himachal Pradesh, 171005, India
| | - Neerja Thakur
- Department of Biotechnology, Himachal Pradesh University, Shimla, Himachal Pradesh, 171005, India
| | - Tek Chand Bhalla
- Department of Biotechnology, Himachal Pradesh University, Shimla, Himachal Pradesh, 171005, India.
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Merlo R, Mattossovich R, Genta M, Valenti A, Di Mauro G, Minassi A, Miggiano R, Perugino G. First thermostable CLIP-tag by rational design applied to an archaeal O-alkyl-guanine-DNA-alkyl-transferase. Comput Struct Biotechnol J 2022; 20:5275-5286. [PMID: 36212535 PMCID: PMC9519396 DOI: 10.1016/j.csbj.2022.09.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Revised: 09/08/2022] [Accepted: 09/08/2022] [Indexed: 11/30/2022] Open
Abstract
Self-labelling protein tags (SLPs) are resourceful tools that revolutionized sensor imaging, having the versatile ability of being genetically fused with any protein of interest and undergoing activation with alternative probes specifically designed for each variant (namely, SNAP-tag, CLIP-tag and Halo-tag). Commercially available SLPs are highly useful in studying molecular aspects of mesophilic organisms, while they fail in characterizing model organisms that thrive in harsh conditions. By applying an integrated computational and structural approach, we designed a engineered variant of the alkylguanine-DNA-alkyl-transferase (OGT) from the hyper-thermophilic archaeon Saccharolobus solfataricus (SsOGT), with no DNA-binding activity, able to covalently react with O6-benzyl-cytosine (BC-) derivatives, obtaining the first thermostable CLIP-tag, named SsOGT-MC8. The presented construct is able to recognize and to covalently bind BC- substrates with a marked specificity, displaying a very low activity on orthogonal benzyl-guanine (BG-) substrate and showing a remarkable thermal stability that broadens the applicability of SLPs. The rational mutagenesis that, starting from SsOGT, led to the production of SsOGT-MC8 was first evaluated by structural predictions to precisely design the chimeric construct, by mutating specific residues involved in protein stability and substrate recognition. The final construct was further validated by biochemical characterization and X-ray crystallography, allowing us to present here the first structural model of a CLIP-tag establishing the molecular determinants of its activity, as well as proposing a general approach for the rational engineering of any O6-alkylguanine-DNA-alkyl-transferase turning it into a SNAP- and a CLIP-tag variant.
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Koirala RP, Pokhrel R, Baral P, Tiwari PB, Chapagain PP, Adhikari NP. Structural insights into the repair mechanism of AGT for methyl-induced DNA damage. Biol Chem 2021; 402:1203-1211. [PMID: 34192828 DOI: 10.1515/hsz-2021-0198] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Accepted: 05/29/2021] [Indexed: 02/06/2023]
Abstract
Methylation induced DNA base-pairing damage is one of the major causes of cancer. O6-alkylguanine-DNA alkyltransferase (AGT) is considered a demethylation agent of the methylated DNA. Structural investigations with thermodynamic properties of the AGT-DNA complex are still lacking. In this report, we modeled two catalytic states of AGT-DNA interactions and an AGT-DNA covalent complex and explored structural features using molecular dynamics (MD) simulations. We utilized the umbrella sampling method to investigate the changes in the free energy of the interactions in two different AGT-DNA catalytic states, one with methylated GUA in DNA and the other with methylated CYS145 in AGT. These non-covalent complexes represent the pre- and post-repair complexes. Therefore, our study encompasses the process of recognition, complex formation, and separation of the AGT and the damaged (methylated) DNA base. We believe that the use of parameters for the amino acid and nucleotide modifications and for the protein-DNA covalent bond will allow investigations of the DNA repair mechanism as well as the exploration of cancer therapeutics targeting the AGT-DNA complexes at various functional states as well as explorations via stabilization of the complex.
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Affiliation(s)
| | - Rudramani Pokhrel
- Department of Physics, Florida International University, Miami, FL, USA
| | - Prabin Baral
- Department of Physics, Florida International University, Miami, FL, USA
| | | | - Prem P Chapagain
- Department of Physics, Florida International University, Miami, FL, USA
- Biomolecular Sciences Institute, Florida International University, Miami, FL, USA
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Farag N, Mattossovich R, Merlo R, Nierzwicki Ł, Palermo G, Porchetta A, Perugino G, Ricci F. Folding-upon-Repair DNA Nanoswitches for Monitoring the Activity of DNA Repair Enzymes. Angew Chem Int Ed Engl 2021; 60:7283-7289. [PMID: 33415794 PMCID: PMC8783695 DOI: 10.1002/anie.202016223] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Indexed: 09/28/2023]
Abstract
We present a new class of DNA-based nanoswitches that, upon enzymatic repair, could undergo a conformational change mechanism leading to a change in fluorescent signal. Such folding-upon-repair DNA nanoswitches are synthetic DNA sequences containing O6 -methyl-guanine (O6 -MeG) nucleobases and labelled with a fluorophore/quencher optical pair. The nanoswitches are rationally designed so that only upon enzymatic demethylation of the O6 -MeG nucleobases they can form stable intramolecular Hoogsteen interactions and fold into an optically active triplex DNA structure. We have first characterized the folding mechanism induced by the enzymatic repair activity through fluorescent experiments and Molecular Dynamics simulations. We then demonstrated that the folding-upon-repair DNA nanoswitches are suitable and specific substrates for different methyltransferase enzymes including the human homologue (hMGMT) and they allow the screening of novel potential methyltransferase inhibitors.
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Affiliation(s)
- Nada Farag
- Department of Chemistry, University of Rome Tor Vergata, Via della Ricerca Scientifica, 00133, Rome, Italy
| | - Rosanna Mattossovich
- Institute of Biosciences and BioResources, National Research Council of Italy, Via Pietro Castellino 111, 80131, Naples, Italy
| | - Rosa Merlo
- Institute of Biosciences and BioResources, National Research Council of Italy, Via Pietro Castellino 111, 80131, Naples, Italy
| | - Łukasz Nierzwicki
- Department of Bioengineering, University of California Riverside, 900 University Avenue, Riverside, CA, 52512, USA
| | - Giulia Palermo
- Department of Bioengineering, University of California Riverside, 900 University Avenue, Riverside, CA, 52512, USA
- Department of Chemistry, University of California Riverside, 900 University Avenue, Riverside, CA, 52512, USA
| | - Alessandro Porchetta
- Department of Chemistry, University of Rome Tor Vergata, Via della Ricerca Scientifica, 00133, Rome, Italy
| | - Giuseppe Perugino
- Institute of Biosciences and BioResources, National Research Council of Italy, Via Pietro Castellino 111, 80131, Naples, Italy
| | - Francesco Ricci
- Department of Chemistry, University of Rome Tor Vergata, Via della Ricerca Scientifica, 00133, Rome, Italy
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Farag N, Mattossovich R, Merlo R, Nierzwicki Ł, Palermo G, Porchetta A, Perugino G, Ricci F. Folding‐upon‐Repair DNA Nanoswitches for Monitoring the Activity of DNA Repair Enzymes. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202016223] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Affiliation(s)
- Nada Farag
- Department of Chemistry University of Rome Tor Vergata Via della Ricerca Scientifica 00133 Rome Italy
| | - Rosanna Mattossovich
- Institute of Biosciences and BioResources National Research Council of Italy Via Pietro Castellino 111 80131 Naples Italy
| | - Rosa Merlo
- Institute of Biosciences and BioResources National Research Council of Italy Via Pietro Castellino 111 80131 Naples Italy
| | - Łukasz Nierzwicki
- Department of Bioengineering University of California Riverside 900 University Avenue Riverside CA 52512 USA
| | - Giulia Palermo
- Department of Bioengineering University of California Riverside 900 University Avenue Riverside CA 52512 USA
- Department of Chemistry University of California Riverside 900 University Avenue Riverside CA 52512 USA
| | - Alessandro Porchetta
- Department of Chemistry University of Rome Tor Vergata Via della Ricerca Scientifica 00133 Rome Italy
| | - Giuseppe Perugino
- Institute of Biosciences and BioResources National Research Council of Italy Via Pietro Castellino 111 80131 Naples Italy
| | - Francesco Ricci
- Department of Chemistry University of Rome Tor Vergata Via della Ricerca Scientifica 00133 Rome Italy
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Di Somma A, Canè C, Moretta A, Cirillo A, Cemič F, Duilio A. Characterization of the Proteins Involved in the DNA Repair Mechanism in M. smegmatis. Int J Mol Sci 2020; 21:ijms21155391. [PMID: 32751237 PMCID: PMC7432924 DOI: 10.3390/ijms21155391] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Revised: 07/24/2020] [Accepted: 07/27/2020] [Indexed: 11/26/2022] Open
Abstract
Several alkylating agents that either occur in the environment or are self-produced can cause DNA-damaging injuries in bacterial cells. Therefore, all microorganisms have developed repair systems that are able to counteract DNA alkylation damage. The adaptive response to alkylation stress in Escherichia coli consists of the Ada operon, which has been widely described; however, the homologous system in Mycobacterium tuberculosis (MTB) has been shown to have a different genetic organization but it is still largely unknown. In order to describe the defense system of MTB, we first investigated the proteins involved in the repair mechanism in the homologous non-pathogenic mycobacterium M. smegmatis. Ogt, Ada-AlkA and FadE8 proteins were recombinantly produced, purified and characterized. The biological role of Ogt was examined using proteomic experiments to identify its protein partners in vivo under stress conditions. Our results suggested the formation of a functional complex between Ogt and Ada-AlkA, which was confirmed both in silico by docking calculations and by gel filtration chromatography. We propose that this stable association allows the complex to fulfill the biological roles exerted by Ada in the homologous E. coli system. Finally, FadE8 was demonstrated to be structurally and functionally related to its E. coli homologous, AidB.
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Affiliation(s)
- Angela Di Somma
- Department of Chemical Sciences, Università Federico II di, 80126 Naples, Italy; (A.D.S.); (C.C.)
- Istituto Nazionale Biostrutture Biostrumentazioni, INBB, 00136 Rome, Italy
| | - Carolina Canè
- Department of Chemical Sciences, Università Federico II di, 80126 Naples, Italy; (A.D.S.); (C.C.)
- CEINGE Biotecnologie Avanzate, 80145 Naples, Italy;
| | - Antonio Moretta
- Department of Science, Università degli Studi della Basilicata, 85100 Potenza, Italy;
| | | | - Franz Cemič
- Department of Mathematics, Natural Sciences and Computer Science, University of Applied Sciences Giessen, Wiesenstr. 14, 35390 Giessen, Germany;
| | - Angela Duilio
- Department of Chemical Sciences, Università Federico II di, 80126 Naples, Italy; (A.D.S.); (C.C.)
- Correspondence:
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