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Albert P, Varga B, Ferenc G, Kiss A. Conversion of the CG specific M.MpeI DNA methyltransferase into an enzyme predominantly methylating CCA and CCC sites. Nucleic Acids Res 2024; 52:1896-1908. [PMID: 38164970 PMCID: PMC10899764 DOI: 10.1093/nar/gkad1217] [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: 09/25/2023] [Revised: 12/04/2023] [Accepted: 12/19/2023] [Indexed: 01/03/2024] Open
Abstract
We used structure guided mutagenesis and directed enzyme evolution to alter the specificity of the CG specific bacterial DNA (cytosine-5) methyltransferase M.MpeI. Methylation specificity of the M.MpeI variants was characterized by digestions with methylation sensitive restriction enzymes and by measuring incorporation of tritiated methyl groups into double-stranded oligonucleotides containing single CC, CG, CA or CT sites. Site specific mutagenesis steps designed to disrupt the specific contacts between the enzyme and the non-substrate base pair of the target sequence (5'-CG/5'-CG) yielded M.MpeI variants with varying levels of CG specific and increasing levels of CA and CC specific MTase activity. Subsequent random mutagenesis of the target recognizing domain coupled with selection for non-CG specific methylation yielded a variant, which predominantly methylates CC dinucleotides, has very low activity on CG and CA sites, and no activity on CT sites. This M.MpeI variant contains a one amino acid deletion (ΔA323) and three substitutions (N324G, R326G and E305N) in the target recognition domain. The mutant enzyme has very strong preference for A and C in the 3' flanking position making it a CCA and CCC specific DNA methyltransferase.
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Affiliation(s)
- Pál Albert
- Laboratory of DNA-Protein Interactions, Institute of Biochemistry, HUN-REN Biological Research Centre, 6726 Szeged, Hungary
- Doctoral School of Biology, Faculty of Science and Informatics, University of Szeged, 6726 Szeged, Hungary
| | - Bence Varga
- Laboratory of DNA-Protein Interactions, Institute of Biochemistry, HUN-REN Biological Research Centre, 6726 Szeged, Hungary
- Doctoral School of Biology, Faculty of Science and Informatics, University of Szeged, 6726 Szeged, Hungary
- Nucleic Acid Synthesis Laboratory, Institute of Plant Biology, HUN-REN Biological Research Centre, 6726 Szeged, Hungary
| | - Györgyi Ferenc
- Nucleic Acid Synthesis Laboratory, Institute of Plant Biology, HUN-REN Biological Research Centre, 6726 Szeged, Hungary
| | - Antal Kiss
- Laboratory of DNA-Protein Interactions, Institute of Biochemistry, HUN-REN Biological Research Centre, 6726 Szeged, Hungary
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Fulk EM, Huh D, Atkinson JT, Lie M, Masiello CA, Silberg JJ. A Split Methyl Halide Transferase AND Gate That Reports by Synthesizing an Indicator Gas. ACS Synth Biol 2020; 9:3104-3113. [PMID: 33104325 DOI: 10.1021/acssynbio.0c00355] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Monitoring microbial reactions in highly opaque or autofluorescent environments like soils, seawater, and wastewater remains challenging. To develop a simple approach for observing post-translational reactions within microbes situated in environmental matrices, we designed a methyl halide transferase (MHT) fragment complementation assay that reports by synthesizing an indicator gas. We show that backbone fission within regions of high sequence variability in the Rossmann domain yields split MHT (sMHT) AND gates whose fragments cooperatively associate to synthesize CH3Br. Additionally, we identify a sMHT whose fragments require fusion to pairs of interacting partner proteins for maximal activity. We also show that sMHT fragments fused to FKBP12 and the FKBP-rapamycin binding domain of mTOR display significantly enhanced CH3Br production in the presence of rapamycin. This gas production is reversed in the presence of the competitive inhibitor of FKBP12/FKPB dimerization, indicating that sMHT is a reversible reporter of post-translational reactions. This sMHT represents the first genetic AND gate that reports on protein-protein interactions via an indicator gas. Because indicator gases can be measured in the headspaces of complex environmental samples, this assay should be useful for monitoring the dynamics of diverse molecular interactions within microbes situated in hard-to-image marine and terrestrial matrices.
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Affiliation(s)
- Emily M. Fulk
- Systems, Synthetic, and Physical Biology Graduate Program, Rice University, 6100 Main Street, MS-180, Houston, Texas 77005, United States
| | - Dongkuk Huh
- Department of Biosciences, Rice University, 6100 Main Street, MS-140, Houston, Texas 77005, United States
| | - Joshua T. Atkinson
- Department of Biosciences, Rice University, 6100 Main Street, MS-140, Houston, Texas 77005, United States
| | - Margaret Lie
- Department of Biosciences, Rice University, 6100 Main Street, MS-140, Houston, Texas 77005, United States
| | - Caroline A. Masiello
- Department of Biosciences, Rice University, 6100 Main Street, MS-140, Houston, Texas 77005, United States
- Department of Earth, Environmental and Planetary Sciences, Rice University, MS 126, Houston, Texas 77005, United States
- Department of Chemistry, Rice University, 6100 Main Street, MS-60, Houston, Texas 77005, United States
| | - Jonathan J. Silberg
- Department of Biosciences, Rice University, 6100 Main Street, MS-140, Houston, Texas 77005, United States
- Department of Bioengineering, Rice University, 6100 Main Street, MS-142, Houston, Texas 77005, United States
- Department of Chemical and Biomolecular Engineering, Rice University, 6100 Main Street, MS-362, Houston, Texas 77005, United States
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Albert P, Varga B, Zsibrita N, Kiss A. Circularly permuted variants of two CG-specific prokaryotic DNA methyltransferases. PLoS One 2018; 13:e0197232. [PMID: 29746549 PMCID: PMC5944983 DOI: 10.1371/journal.pone.0197232] [Citation(s) in RCA: 4] [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: 01/26/2018] [Accepted: 04/27/2018] [Indexed: 01/06/2023] Open
Abstract
The highly similar prokaryotic DNA (cytosine-5) methyltransferases (C5-MTases) M.MpeI and M.SssI share the specificity of eukaryotic C5-MTases (5'-CG), and can be useful research tools in the study of eukaryotic DNA methylation and epigenetic regulation. In an effort to improve the stability and solubility of complementing fragments of the two MTases, genes encoding circularly permuted (CP) variants of M.MpeI and M.SssI were created, and cloned in a plasmid vector downstream of an arabinose-inducible promoter. MTase activity of the CP variants was tested by digestion of the plasmids with methylation-sensitive restriction enzymes. Eleven of the fourteen M.MpeI permutants and six of the seven M.SssI permutants had detectable MTase activity as indicated by the full or partial protection of the plasmid carrying the cpMTase gene. Permutants cp62M.MpeI and cp58M.SssI, in which the new N-termini are located between conserved motifs II and III, had by far the highest activity. The activity of cp62M.MpeI was comparable to the activity of wild-type M.MpeI. Based on the location of the split sites, the permutants possessing MTase activity can be classified in ten types. Although most permutation sites were designed to fall outside of conserved motifs, and the MTase activity of the permutants measured in cell extracts was in most cases substantially lower than that of the wild-type enzyme, the high proportion of circular permutation topologies compatible with MTase activity is remarkable, and is a new evidence for the structural plasticity of C5-MTases. A computer search of the REBASE database identified putative C5-MTases with CP arrangement. Interestingly, all natural circularly permuted C5-MTases appear to represent only one of the ten types of permutation topology created in this work.
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Affiliation(s)
- Pál Albert
- Institute of Biochemistry, Biological Research Centre of the Hungarian Academy of Sciences, Szeged, Hungary
- Doctoral School in Biology, Faculty of Science and Informatics, University of Szeged, Szeged, Hungary
| | - Bence Varga
- Institute of Biochemistry, Biological Research Centre of the Hungarian Academy of Sciences, Szeged, Hungary
| | - Nikolett Zsibrita
- Institute of Biochemistry, Biological Research Centre of the Hungarian Academy of Sciences, Szeged, Hungary
- Doctoral School in Biology, Faculty of Science and Informatics, University of Szeged, Szeged, Hungary
| | - Antal Kiss
- Institute of Biochemistry, Biological Research Centre of the Hungarian Academy of Sciences, Szeged, Hungary
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Drikic M, De Buck J. Split trehalase as a versatile reporter for a wide range of biological analytes. Biotechnol Bioeng 2018; 115:1128-1136. [DOI: 10.1002/bit.26556] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Revised: 01/17/2018] [Accepted: 01/30/2018] [Indexed: 11/06/2022]
Affiliation(s)
- Marija Drikic
- Faculty of Veterinary Medicine, Department of Production Animal Health; University of Calgary; Calgary Alberta Canada
| | - Jeroen De Buck
- Faculty of Veterinary Medicine, Department of Production Animal Health; University of Calgary; Calgary Alberta Canada
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Waryah CB, Moses C, Arooj M, Blancafort P. Zinc Fingers, TALEs, and CRISPR Systems: A Comparison of Tools for Epigenome Editing. Methods Mol Biol 2018. [PMID: 29524128 DOI: 10.1007/978-1-4939-7774-1_2] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The completion of genome, epigenome, and transcriptome mapping in multiple cell types has created a demand for precision biomolecular tools that allow researchers to functionally manipulate DNA, reconfigure chromatin structure, and ultimately reshape gene expression patterns. Epigenetic editing tools provide the ability to interrogate the relationship between epigenetic modifications and gene expression. Importantly, this information can be exploited to reprogram cell fate for both basic research and therapeutic applications. Three different molecular platforms for epigenetic editing have been developed: zinc finger proteins (ZFs), transcription activator-like effectors (TALEs), and the system of Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) and CRISPR-associated (Cas) proteins. These platforms serve as custom DNA-binding domains (DBDs), which are fused to epigenetic modifying domains to manipulate epigenetic marks at specific sites in the genome. The addition and/or removal of epigenetic modifications reconfigures local chromatin structure, with the potential to provoke long-lasting changes in gene transcription. Here we summarize the molecular structure and mechanism of action of ZF, TALE, and CRISPR platforms and describe their applications for the locus-specific manipulation of the epigenome. The advantages and disadvantages of each platform will be discussed with regard to genomic specificity, potency in regulating gene expression, and reprogramming cell phenotypes, as well as ease of design, construction, and delivery. Finally, we outline potential applications for these tools in molecular biology and biomedicine and identify possible barriers to their future clinical implementation.
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Affiliation(s)
- Charlene Babra Waryah
- Cancer Epigenetics Group, The Harry Perkins Institute of Medical Research, Nedlands, Perth, WA, Australia
| | - Colette Moses
- Cancer Epigenetics Group, The Harry Perkins Institute of Medical Research, Nedlands, Perth, WA, Australia
- School of Human Sciences, The University of Western Australia, Perth, WA, Australia
| | - Mahira Arooj
- Cancer Epigenetics Group, The Harry Perkins Institute of Medical Research, Nedlands, Perth, WA, Australia
- School of Biomedical Sciences, Curtin Health Innovation Research Institute, Curtin University, Perth, WA, Australia
| | - Pilar Blancafort
- Cancer Epigenetics Group, The Harry Perkins Institute of Medical Research, Nedlands, Perth, WA, Australia.
- School of Human Sciences, The University of Western Australia, Perth, WA, Australia.
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Chaikind B, Ostermeier M. Directed evolution of improved zinc finger methyltransferases. PLoS One 2014; 9:e96931. [PMID: 24810747 PMCID: PMC4014571 DOI: 10.1371/journal.pone.0096931] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2014] [Accepted: 04/14/2014] [Indexed: 01/09/2023] Open
Abstract
The ability to target DNA methylation toward a single, user-designated CpG site in vivo may have wide applicability for basic biological and biomedical research. A tool for targeting methylation toward single sites could be used to study the effects of individual methylation events on transcription, protein recruitment to DNA, and the dynamics of such epigenetic alterations. Although various tools for directing methylation to promoters exist, none offers the ability to localize methylation solely to a single CpG site. In our ongoing research to create such a tool, we have pursued a strategy employing artificially bifurcated DNA methyltransferases; each methyltransferase fragment is fused to zinc finger proteins with affinity for sequences flanking a targeted CpG site for methylation. We sought to improve the targeting of these enzymes by reducing the methyltransferase activity at non-targeted sites while maintaining high levels of activity at a targeted site. Here we demonstrate an in vitro directed evolution selection strategy to improve methyltransferase specificity and use it to optimize an engineered zinc finger methyltransferase derived from M.SssI. The unusual restriction enzyme McrBC is a key component of this strategy and is used to select against methyltransferases that methylate multiple sites on a plasmid. This strategy allowed us to quickly identify mutants with high levels of methylation at the target site (up to ∼80%) and nearly unobservable levels of methylation at a off-target sites (<1%), as assessed in E. coli. We also demonstrate that replacing the zinc finger domains with new zinc fingers redirects the methylation to a new target CpG site flanked by the corresponding zinc finger binding sequences.
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Affiliation(s)
- Brian Chaikind
- Chemistry-Biology Interface Graduate Program, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Marc Ostermeier
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, Maryland, United States of America
- * E-mail:
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Chen H, Kazemier HG, de Groote ML, Ruiters MHJ, Xu GL, Rots MG. Induced DNA demethylation by targeting Ten-Eleven Translocation 2 to the human ICAM-1 promoter. Nucleic Acids Res 2013; 42:1563-74. [PMID: 24194590 PMCID: PMC3919596 DOI: 10.1093/nar/gkt1019] [Citation(s) in RCA: 110] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Increasing evidence indicates that active DNA demethylation is involved in several processes in mammals, resulting in developmental stage-specificity and cell lineage-specificity. The recently discovered Ten-Eleven Translocation (TET) dioxygenases are accepted to be involved in DNA demethylation by initiating 5-mC oxidation. Aberrant DNA methylation profiles are associated with many diseases. For example in cancer, hypermethylation results in silencing of tumor suppressor genes. Such silenced genes can be re-expressed by epigenetic drugs, but this approach has genome-wide effects. In this study, fusions of designer DNA binding domains to TET dioxygenase family members (TET1, -2 or -3) were engineered to target epigenetically silenced genes (ICAM-1, EpCAM). The effects on targeted CpGs’ methylation and on expression levels of the target genes were assessed. The results indicated demethylation of targeted CpG sites in both promoters for targeted TET2 and to a lesser extent for TET1, but not for TET3. Interestingly, we observed re-activation of transcription of ICAM-1. Thus, our work suggests that we provided a mechanism to induce targeted DNA demethylation, which facilitates re-activation of expression of the target genes. Furthermore, this Epigenetic Editing approach is a powerful tool to investigate functions of epigenetic writers and erasers and to elucidate consequences of epigenetic marks.
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Affiliation(s)
- Hui Chen
- Epigenetic Editing, Department of Pathology and Medical Biology, University Medical Center Groningen, University of Groningen, Hanzeplein1, 9713 GZ Groningen, The Netherlands, The State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031, China and Synvolux Therapeutics Inc., LJ. Zielstraweg 1, 9713 GX Groningen, The Netherlands
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de Groote ML, Verschure PJ, Rots MG. Epigenetic Editing: targeted rewriting of epigenetic marks to modulate expression of selected target genes. Nucleic Acids Res 2012; 40:10596-613. [PMID: 23002135 PMCID: PMC3510492 DOI: 10.1093/nar/gks863] [Citation(s) in RCA: 128] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Despite significant advances made in epigenetic research in recent decades, many questions remain unresolved, especially concerning cause and consequence of epigenetic marks with respect to gene expression modulation (GEM). Technologies allowing the targeting of epigenetic enzymes to predetermined DNA sequences are uniquely suited to answer such questions and could provide potent (bio)medical tools. Toward the goal of gene-specific GEM by overwriting epigenetic marks (Epigenetic Editing, EGE), instructive epigenetic marks need to be identified and their writers/erasers should then be fused to gene-specific DNA binding domains. The appropriate epigenetic mark(s) to change in order to efficiently modulate gene expression might have to be validated for any given chromatin context and should be (mitotically) stable. Various insights in such issues have been obtained by sequence-specific targeting of epigenetic enzymes, as is presented in this review. Features of such studies provide critical aspects for further improving EGE. An example of this is the direct effect of the edited mark versus the indirect effect of recruited secondary proteins by targeting epigenetic enzymes (or their domains). Proof-of-concept of expression modulation of an endogenous target gene is emerging from the few EGE studies reported. Apart from its promise in correcting disease-associated epi-mutations, EGE represents a powerful tool to address fundamental epigenetic questions.
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Affiliation(s)
- Marloes L de Groote
- Department of Pathology and Medical Biology, University Medical Center Groningen, University of Groningen, Hanzeplein 1 EA11, 9713 GZ, Groningen, The Netherlands
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Chaikind B, Kilambi KP, Gray JJ, Ostermeier M. Targeted DNA methylation using an artificially bisected M.HhaI fused to zinc fingers. PLoS One 2012; 7:e44852. [PMID: 22984575 PMCID: PMC3439449 DOI: 10.1371/journal.pone.0044852] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2012] [Accepted: 08/08/2012] [Indexed: 11/18/2022] Open
Abstract
Little is known about the effects of single DNA methylation events on gene transcription. The ability to direct the methylation toward a single unique site within a genome would have broad use as a tool to study the effects of specific epigenetic changes on transcription. A targeted enzyme might also be useful in a therapy for diseases with an epigenetic component or as a means to site-specifically label DNA. Previous studies have sought to target methyltransferase activity by fusing DNA binding proteins to methyltransferases. However, the methyltransferase domain remains active even when the DNA binding protein is unbound, resulting in significant off-target methylation. A better strategy would make methyltransferase activity contingent upon the DNA binding protein’s association with its DNA binding site. We have designed targeted methyltransferases by fusing zinc fingers to the fragments of artificially-bisected, assembly-compromised methyltransferases. The zinc fingers’ binding sites flank the desired target site for methylation. Zinc finger binding localizes the two fragments near each other encouraging their assembly only over the desired site. Through a combination of molecular modeling and experimental optimization in E. coli, we created an engineered methyltransferase derived from M.HhaI with 50–60% methylation at a target site and nearly undetectable levels of methylation at a non-target M.HhaI site (1.4±2.4%). Using a restriction digestion assay, we demonstrate that localization of both fragments synergistically increases methylation at the target site, illustrating the promise of our approach.
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Affiliation(s)
- Brian Chaikind
- Chemistry-Biology Interface Graduate Program, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Krishna Praneeth Kilambi
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Jeffrey J. Gray
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Marc Ostermeier
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, Maryland, United States of America
- * E-mail:
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