1
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Liu D, Zhou X, Zhao J. Prognostic signature and immune efficacy of m 1A-, m 5C-, m 6A-, m 7G-, and DNA methylation-related regulators in hepatocellular carcinoma. J Cancer 2024; 15:4287-4300. [PMID: 38947378 PMCID: PMC11212094 DOI: 10.7150/jca.95730] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2024] [Accepted: 05/19/2024] [Indexed: 07/02/2024] Open
Abstract
Background: Hepatocellular carcinoma (HCC) is the main type of primary liver cancer, and its related death ranks third worldwide. The curative methods and progress prediction markers of HCC are not sufficient enough. Nevertheless, little progress has been made in the signature of m1A-, m5C-, m6A-, m7G-, and DNA methylation of HCC. Results: We calibrated a risk gene signature model that can be used to categorize HCC patients based on univariate, multivariate, and LASSO Cox regression analysis. This gene signature classified the patients into high- and low-risk subgroups. Patients in the high-risk group showed significantly reduced overall survival (OS) compared with patients in the low-risk group. The gene set variation analysis (GSVA), immune infiltration, and immunotherapy response were analyzed. The results demonstrated that an immunosuppressive environment was exited and the high-risk group had higher sensitivity to 5-fluorouracil, cisplatin, sorafenib, tamoxifen, and epirubicin. These results indicated personalized therapy should be taken into consideration. Conclusions: Our findings enriched our understanding of the molecular heterogeneity, tumor microenvironment (TME), and drug susceptibility of HCC. m1A-, m5C-, m6A-, m7G-, and DNA methylation-related regulators may be promising biomarkers for future research.
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Affiliation(s)
- Donghong Liu
- Department of Special Medical Care, Shanghai Eastern Hepatobiliary Surgery Hospital, Shanghai, 200438, China
| | - Xinyu Zhou
- Department of Epidemiology, Naval Medical University, Shanghai, 200433, China
| | - Jun Zhao
- Department of Special Medical Care, Shanghai Eastern Hepatobiliary Surgery Hospital, Shanghai, 200438, China
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2
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Matsuda T, Hori H, Yamagami R. Rational design of oligonucleotides for enhanced in vitro transcription of small RNA. RNA (NEW YORK, N.Y.) 2024; 30:710-727. [PMID: 38423625 PMCID: PMC11098460 DOI: 10.1261/rna.079923.123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2023] [Accepted: 02/14/2024] [Indexed: 03/02/2024]
Abstract
All kinds of RNA molecules can be produced by in vitro transcription using T7 RNA polymerase using DNA templates obtained by solid-phase chemical synthesis, primer extension, PCR, or DNA cloning. The oligonucleotide design, however, is a challenge to nonexperts as this relies on a set of rules that have been established empirically over time. Here, we describe a Python program to facilitate the rational design of oligonucleotides, calculated with kinetic parameters for enhanced in vitro transcription (ROCKET). The Python tool uses thermodynamic parameters, performs folding-energy calculations, and selects oligonucleotides suitable for the polymerase extension reaction. These oligonucleotides improve yields of template DNA. With the oligonucleotides selected by the program, the tRNA transcripts can be prepared by a one-pot reaction of the DNA polymerase extension reaction and the transcription reaction. Also, the ROCKET-selected oligonucleotides provide greater transcription yields than that from oligonucleotides selected by Primerize, a leading software for designing oligonucleotides for in vitro transcription, due to the enhancement of template DNA synthesis. Apart from over 50 tRNA genes tested, an in vitro transcribed self-cleaving ribozyme was found to have catalytic activity. In addition, the program can be applied to the synthesis of mRNA, demonstrating the wide applicability of the ROCKET software.
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MESH Headings
- Transcription, Genetic
- Oligonucleotides/chemistry
- Oligonucleotides/genetics
- Oligonucleotides/chemical synthesis
- Software
- DNA-Directed RNA Polymerases/metabolism
- DNA-Directed RNA Polymerases/genetics
- RNA, Catalytic/genetics
- RNA, Catalytic/metabolism
- RNA, Catalytic/chemistry
- Thermodynamics
- RNA, Transfer/genetics
- RNA, Transfer/chemistry
- RNA, Transfer/metabolism
- Kinetics
- RNA, Messenger/genetics
- RNA, Messenger/chemistry
- RNA, Messenger/metabolism
- Viral Proteins/genetics
- Viral Proteins/metabolism
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Affiliation(s)
- Teppei Matsuda
- Department of Applied Chemistry, Graduate School of Science and Engineering, Ehime University, Matsuyama, Ehime 790-8577, Japan
| | - Hiroyuki Hori
- Department of Applied Chemistry, Graduate School of Science and Engineering, Ehime University, Matsuyama, Ehime 790-8577, Japan
| | - Ryota Yamagami
- Department of Applied Chemistry, Graduate School of Science and Engineering, Ehime University, Matsuyama, Ehime 790-8577, Japan
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3
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Smoczynski J, Yared MJ, Meynier V, Barraud P, Tisné C. Advances in the Structural and Functional Understanding of m 1A RNA Modification. Acc Chem Res 2024. [PMID: 38331425 PMCID: PMC10882958 DOI: 10.1021/acs.accounts.3c00568] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/10/2024]
Abstract
ConspectusRNA modification is a co- or post-transcriptional process by which specific nucleotides are chemically altered by enzymes after their initial incorporation into the RNA chain, expanding the chemical and functional diversity of RNAs. Our understanding of RNA modifications has changed dramatically in recent years. In the past decade, RNA methyltransferases (MTases) have been highlighted in numerous clinical studies and disease models, modifications have been found to be dynamically regulated by demodification enzymes, and significant technological advances have been made in the fields of RNA sequencing, mass spectrometry, and structural biology. Among RNAs, transfer RNAs (tRNAs) exhibit the greatest diversity and density of post-transcriptional modifications, which allow for potential cross-talks and regulation during their incorporation. N1-methyladenosine (m1A) modification is found in tRNAs at positions 9, 14, 16, 22, 57, and 58, depending on the tRNA and organism.Our laboratory has used and developed a large panel of tools to decipher the different mechanisms used by m1A tRNA MTases to recognize and methylate tRNA. We have solved the structures of TrmI from Thermus thermophilus (m1A58), TrmK from Bacillus subtilis (m1A22), and human TRMT10C (m1A9). These MTases do not share the same structure or organization to recognize tRNAs, but they all modify an adenosine, forming a non-Watson-Crick (WC) interaction. For TrmK, nuclear magnetic resonance (NMR) chemical shift mapping of the binding interface between TrmK and tRNASer was invaluable to build a TrmK/tRNA model, where both domains of TrmK participate in the binding of a full-length L-shaped tRNA and where the non-WC purine 13-A22 base pair positions the A22 N1-atom close to the methyl of the S-adenosyl-l-methionine (SAM) TrmK cofactor. For TRMT10C, cryoEM structures showed the MTase poised to N1-methylate A9 or G9 in tRNA and revealed different steps of tRNA maturation, where TRMT10C acts as a tRNA binding platform for sequential docking of each maturation enzyme. This work confers a role for TRMT10C in tRNA quality control and provides a framework to understand the link between mitochondrial tRNA maturation dysfunction and diseases.Methods to directly detect the incorporation of modifications during tRNA biosynthesis are rare and do not provide easy access to the temporality of their introduction. To this end, we have introduced time-resolved NMR to monitor tRNA maturation in the cellular environment. Combined with genetic and biochemical approaches involving the synthesis of specifically modified tRNAs, our methodology revealed that some modifications are incorporated in a defined sequential order, controlled by cross-talks between modification events. In particular, a strong modification circuit, namely Ψ55 → m5U54 → m1A58, controls the modification process in the T-arm of yeast elongator tRNAs. Conversely, we showed that m1A58 is efficiently introduced on unmodified initiator tRNAiMet without the need of any prior modification. Two distinct pathways are therefore followed for m1A58 incorporation in elongator and initiator tRNAs.We are undoubtedly entering an exciting period for the elucidation of the functions of RNA modifications and the intricate mechanisms by which modification enzymes identify and alter their RNA substrates. These are promising directions for the field of epitranscriptomics.
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Affiliation(s)
- Jakub Smoczynski
- Université Paris Cité, CNRS, Institut de Biologie Physico-Chimique, IBPC, Expression Génétique Microbienne, Paris 75005, France
| | - Marcel-Joseph Yared
- Université Paris Cité, CNRS, Institut de Biologie Physico-Chimique, IBPC, Expression Génétique Microbienne, Paris 75005, France
| | - Vincent Meynier
- Université Paris Cité, CNRS, Institut de Biologie Physico-Chimique, IBPC, Expression Génétique Microbienne, Paris 75005, France
| | - Pierre Barraud
- Université Paris Cité, CNRS, Institut de Biologie Physico-Chimique, IBPC, Expression Génétique Microbienne, Paris 75005, France
| | - Carine Tisné
- Université Paris Cité, CNRS, Institut de Biologie Physico-Chimique, IBPC, Expression Génétique Microbienne, Paris 75005, France
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4
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Yamagami R, Hori H. Application of mutational profiling: New functional analyses reveal the tRNA recognition mechanism of tRNA m 1A22 methyltransferase. J Biol Chem 2023; 299:102759. [PMID: 36462666 PMCID: PMC9801127 DOI: 10.1016/j.jbc.2022.102759] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2022] [Revised: 11/22/2022] [Accepted: 11/23/2022] [Indexed: 12/05/2022] Open
Abstract
Transfer RNAs undergo diverse posttranscriptional modifications to regulate a myriad of cellular events including translation, stress response, and viral replication. These posttranscriptional modifications are synthesized by site-specific modification enzymes. Recent RNA-seq techniques have revealed multiple features of tRNA such as tRNA abundance, tRNA modification, and tRNA structure. Here, we adapt a tRNA-sequencing technique and design a new functional analysis where we perform mutational profiling of tRNA modifications to gain mechanistic insights into how tRNA modification enzymes recognize substrate tRNA. Profiling of Geobacillus stearothermophilus tRNAs and protein orthology analysis predict the existence of natural modifications in 44 tRNA molecular species of G. stearothermophilus. We selected the 1-methyladenosine modification at position 22 (m1A22) and tRNA (m1A22) methyltransferase (TrmK) for further analysis. Relative quantification of m1A22 levels in 59 tRNA transcripts by mutational profiling reveals that TrmK selectively methylates a subset of tRNAs. Using 240 variants of tRNALeu transcripts, we demonstrate the conserved nucleosides including U8, A14, G15, G18, G19, U55, Purine57, and A58 are important for the methyl transfer reaction of TrmK. Additional biochemical experiments reveal that TrmK strictly recognizes U8, A14, G18, and U55 in tRNA. Furthermore, these findings from tRNALeu variants were crossvalidated using variants of three different tRNA species. Finally, a model of the TrmK-tRNA complex structure was constructed based on our findings and previous biochemical and structural studies by others. Collectively, our study expands functional analyses of tRNA modification enzyme in a high-throughput manner where our assay rapidly identifies substrates from a large pool of tRNAs.
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Affiliation(s)
- Ryota Yamagami
- Department of Materials Science and Biotechnology, Graduate School of Science and Engineering, Ehime University, Matsuyama, Ehime, Japan.
| | - Hiroyuki Hori
- Department of Materials Science and Biotechnology, Graduate School of Science and Engineering, Ehime University, Matsuyama, Ehime, Japan.
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5
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Sweeney P, Galliford A, Kumar A, Raju D, Krishna NB, Sutherland E, Leo CJ, Fisher G, Lalitha R, Muthuraj L, Sigamani G, Oehler V, Synowsky S, Shirran SL, Gloster TM, Czekster CM, Kumar P, da Silva RG. Structure, dynamics, and molecular inhibition of the Staphylococcus aureus m 1A22-tRNA methyltransferase TrmK. J Biol Chem 2022; 298:102040. [PMID: 35595101 PMCID: PMC9190014 DOI: 10.1016/j.jbc.2022.102040] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2021] [Revised: 05/02/2022] [Accepted: 05/04/2022] [Indexed: 11/29/2022] Open
Abstract
The enzyme m1A22-tRNA methyltransferase (TrmK) catalyzes the transfer of a methyl group to the N1 of adenine 22 in bacterial tRNAs. TrmK is essential for Staphylococcus aureus survival during infection but has no homolog in mammals, making it a promising target for antibiotic development. Here, we characterize the structure and function of S. aureus TrmK (SaTrmK) using X-ray crystallography, binding assays, and molecular dynamics simulations. We report crystal structures for the SaTrmK apoenzyme as well as in complexes with methyl donor SAM and co-product product SAH. Isothermal titration calorimetry showed that SAM binds to the enzyme with favorable but modest enthalpic and entropic contributions, whereas SAH binding leads to an entropic penalty compensated for by a large favorable enthalpic contribution. Molecular dynamics simulations point to specific motions of the C-terminal domain being altered by SAM binding, which might have implications for tRNA recruitment. In addition, activity assays for SaTrmK-catalyzed methylation of A22 mutants of tRNALeu demonstrate that the adenine at position 22 is absolutely essential. In silico screening of compounds suggested the multifunctional organic toxin plumbagin as a potential inhibitor of TrmK, which was confirmed by activity measurements. Furthermore, LC-MS data indicated the protein was covalently modified by one equivalent of the inhibitor, and proteolytic digestion coupled with LC-MS identified Cys92 in the vicinity of the SAM-binding site as the sole residue modified. These results identify a cryptic binding pocket of SaTrmK, laying a foundation for future structure-based drug discovery.
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Affiliation(s)
- Pamela Sweeney
- School of Biology, Biomedical Sciences Research Complex, University of St Andrews, St Andrews KY16 9ST, UK
| | - Ashleigh Galliford
- School of Biology, Biomedical Sciences Research Complex, University of St Andrews, St Andrews KY16 9ST, UK
| | | | - Dinesh Raju
- Kcat Enzymatic Private Limited, Bangalore, India
| | | | - Emmajay Sutherland
- School of Biology, Biomedical Sciences Research Complex, University of St Andrews, St Andrews KY16 9ST, UK
| | - Caitlin J Leo
- School of Biology, Biomedical Sciences Research Complex, University of St Andrews, St Andrews KY16 9ST, UK
| | - Gemma Fisher
- School of Biology, Biomedical Sciences Research Complex, University of St Andrews, St Andrews KY16 9ST, UK
| | | | | | | | - Verena Oehler
- School of Biology, Biomedical Sciences Research Complex, University of St Andrews, St Andrews KY16 9ST, UK
| | - Silvia Synowsky
- School of Biology, Biomedical Sciences Research Complex, University of St Andrews, St Andrews KY16 9ST, UK
| | - Sally L Shirran
- School of Biology, Biomedical Sciences Research Complex, University of St Andrews, St Andrews KY16 9ST, UK
| | - Tracey M Gloster
- School of Biology, Biomedical Sciences Research Complex, University of St Andrews, St Andrews KY16 9ST, UK
| | - Clarissa M Czekster
- School of Biology, Biomedical Sciences Research Complex, University of St Andrews, St Andrews KY16 9ST, UK
| | - Pravin Kumar
- Kcat Enzymatic Private Limited, Bangalore, India.
| | - Rafael G da Silva
- School of Biology, Biomedical Sciences Research Complex, University of St Andrews, St Andrews KY16 9ST, UK.
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6
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tRNA modifications and their potential roles in pancreatic cancer. Arch Biochem Biophys 2021; 714:109083. [PMID: 34785212 DOI: 10.1016/j.abb.2021.109083] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2021] [Revised: 11/05/2021] [Accepted: 11/06/2021] [Indexed: 12/23/2022]
Abstract
Since the breakthrough discovery of N6-methyladenosine (m6A), the field of RNA epitranscriptomics has attracted increasing interest in the biological sciences. Transfer RNAs (tRNAs) are extensively modified, and various modifications play a crucial role in the formation and stability of tRNA, which is universally required for accurate and efficient functioning of tRNA. Abnormal tRNA modification can lead to tRNA degradation or specific cleavage of tRNA into fragmented derivatives, thus affecting the translation process and frequently accompanying a variety of human diseases. Increasing evidence suggests that tRNA modification pathways are also misregulated in human cancers. In this review, we summarize tRNA modifications and their biological functions, describe the type and frequency of tRNA modification alterations in cancer, and highlight variations in tRNA-modifying enzymes and the multiple functions that they regulate in different types of cancers. Furthermore, the current implications and the potential role of tRNA modifications in the progression of pancreatic cancer are discussed. Collectively, this review describes recent advances in tRNA modification in cancers and its potential significance in pancreatic cancer. Further study of the mechanism of tRNA modifications in pancreatic cancer may provide possibilities for therapies targeting enzymes responsible for regulating tRNA modifications in pancreatic cancer.
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7
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Partially modified tRNAs for the study of tRNA maturation and function. Methods Enzymol 2021; 658:225-250. [PMID: 34517948 DOI: 10.1016/bs.mie.2021.06.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Transfer RNA (tRNA) is the most highly and diversely modified class of RNA in all domains of life. However, we still have only a limited understanding of the concerted action of the many enzymes that modify tRNA during tRNA maturation and the synergistic functions of tRNA modifications for protein synthesis. Here, we describe the preparation of in vitro transcribed tRNAs with a partial set of defined modifications and the use of partially modified tRNAs in biochemical assays. By comparing the affinity and activity of tRNA modification enzymes for partially modified and unmodified tRNAs, we gain insight into the preferred pathways of tRNA maturation. Additionally, partially modified tRNAs will be highly useful to investigate the importance of tRNA modifications for tRNA function during translation including the interaction with aminoacyl-tRNA synthases, translation factors and the ribosome. Thereby, the methods described here lay the foundation for understanding the mechanistic function of tRNA modifications.
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8
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Catala M, Gato A, Tisné C, Barraud P. 1H, 15N chemical shift assignments of the imino groups of yeast tRNA Phe: influence of the post-transcriptional modifications. BIOMOLECULAR NMR ASSIGNMENTS 2020; 14:169-174. [PMID: 32239363 DOI: 10.1007/s12104-020-09939-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Accepted: 03/26/2020] [Indexed: 06/11/2023]
Abstract
Transfer RNAs (tRNAs) are heavily decorated with post-transcriptional modifications during their biosynthesis. To fulfil their functions within cells, tRNAs undergo a tightly controlled biogenesis process leading to the formation of mature tRNAs. In particular, the introduction of post-transcriptional modifications in tRNAs is controlled and influenced by multiple factors. In turn, tRNA biological functions are often modulated by their modifications. Although modifications play essential roles in tRNA biology, methods to directly detect their introduction during tRNA maturation are rare and do not easily provide information on the temporality of modification events. To obtain information on the tRNA maturation process, we have developed a methodology, using NMR as a tool to monitor tRNA maturation in a non-disruptive and continuous fashion in cellular extracts. Here we report the 1H,15N chemical shift assignments of imino groups in three forms of the yeast tRNAPhe differing in their modification content. These assignments are a prerequisite for the time-resolved NMR monitoring of yeast tRNAPhe maturation in yeast extracts.
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Affiliation(s)
- Marjorie Catala
- Expression Génétique Microbienne, UMR 8261, CNRS, Université de Paris, Institut de Biologie Physico-Chimique (IBPC), 13 rue Pierre et Marie Curie, 75005, Paris, France
| | - Alexandre Gato
- Expression Génétique Microbienne, UMR 8261, CNRS, Université de Paris, Institut de Biologie Physico-Chimique (IBPC), 13 rue Pierre et Marie Curie, 75005, Paris, France
| | - Carine Tisné
- Expression Génétique Microbienne, UMR 8261, CNRS, Université de Paris, Institut de Biologie Physico-Chimique (IBPC), 13 rue Pierre et Marie Curie, 75005, Paris, France
| | - Pierre Barraud
- Expression Génétique Microbienne, UMR 8261, CNRS, Université de Paris, Institut de Biologie Physico-Chimique (IBPC), 13 rue Pierre et Marie Curie, 75005, Paris, France.
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9
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Schultz SKL, Kothe U. tRNA elbow modifications affect the tRNA pseudouridine synthase TruB and the methyltransferase TrmA. RNA (NEW YORK, N.Y.) 2020; 26:1131-1142. [PMID: 32385137 PMCID: PMC7430675 DOI: 10.1261/rna.075473.120] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Accepted: 05/04/2020] [Indexed: 05/20/2023]
Abstract
tRNAs constitute the most highly modified class of RNA. Every tRNA contains a unique set of modifications, and Ψ55, m5U54, and m7G46 are frequently found within the elbow of the tRNA structure. Despite the abundance of tRNA modifications, we are only beginning to understand the orchestration of modification enzymes during tRNA maturation. Here, we investigated whether pre-existing modifications impact the binding affinity or catalysis by tRNA elbow modification enzymes. Specifically, we focused on the Escherichia coli enzymes TruB, TrmA, and TrmB which generate Ψ55, m5U54, and m7G46, respectively. tRNAs containing a single modification were prepared, and the binding and activity preferences of purified E. coli TrmA, TruB, and TrmB were examined in vitro. TruB preferentially binds and modifies unmodified tRNA. TrmA prefers to modify unmodified tRNA, but binds most tightly to tRNA that already contains Ψ55. In contrast, binding and modification by TrmB is insensitive to the tRNA modification status. Our results suggest that TrmA and TruB are likely to act on mostly unmodified tRNA precursors during the early stages of tRNA maturation whereas TrmB presumably acts on later tRNA intermediates that are already partially modified. In conclusion, we uncover the mechanistic basis for the preferred modification order in the E. coli tRNA elbow region.
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Affiliation(s)
- Sarah Kai-Leigh Schultz
- Alberta RNA Research and Training Institute, Department of Chemistry and Biochemistry, University of Lethbridge, Lethbridge, AB, Canada T1K 3M4
| | - Ute Kothe
- Alberta RNA Research and Training Institute, Department of Chemistry and Biochemistry, University of Lethbridge, Lethbridge, AB, Canada T1K 3M4
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10
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Mariasina SS, Chang CF, Petrova OA, Efimov SV, Klochkov VV, Kechko OI, Mitkevich VA, Sergiev PV, Dontsova OA, Polshakov VI. Williams-Beuren syndrome-related methyltransferase WBSCR27: cofactor binding and cleavage. FEBS J 2020; 287:5375-5393. [PMID: 32255258 DOI: 10.1111/febs.15320] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Revised: 02/20/2020] [Accepted: 03/30/2020] [Indexed: 11/28/2022]
Abstract
Williams-Beuren syndrome, characterized by numerous physiological and mental problems, is caused by the heterozygous deletion of chromosome region 7q11.23, which results in the disappearance of 26 protein-coding genes. Protein WBSCR27 is a product of one of these genes whose biological function has not yet been established and for which structural information has been absent until now. Using NMR, we investigated the structural and functional properties of murine WBSCR27. For protein in the apo form and in a complex with S-(5'-adenosyl)-l-homocysteine (SAH), a complete NMR resonance assignment has been obtained and the secondary structure has been determined. This information allows us to attribute WBSCR27 to Class I methyltransferases. The interaction of WBSCR27 with the cofactor S-(5'-adenosyl)-l-methionine (SAM) and its metabolic products - SAH, 5'-deoxy-5'-methylthioadenosine (MTA) and 5'-deoxyadenosine (5'dAdo) - was studied by NMR and isothermal titration calorimetry. SAH binds WBSCR27 much tighter than SAM, leaving open the question of cofactor turnover in the methylation reaction. One possible answer to this question is the presence of weak but detectable nucleosidase activity for WBSCR27. We found that the enzyme catalyses the cleavage of the adenine moiety from SAH, MTA and 5'dAdo, similar to the action of bacterial SAH/MTA nucleosidases. We also found that the binding of SAM or SAH causes a significant change in the structure of WBSCR27 and in the conformational mobility of the protein fragments, which can be attributed to the substrate recognition site. This indicates that the binding of the cofactor modulates the folding of the substrate-recognizing region of the enzyme.
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Affiliation(s)
| | - Chi-Fon Chang
- Genomics Research Center, Academia Sinica, Taipei, Taiwan
| | | | - Sergey V Efimov
- NMR Laboratory, Institute of Physics, Kazan Federal University, Russia
| | | | - Olga I Kechko
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow, Russia
| | - Vladimir A Mitkevich
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow, Russia
| | - Petr V Sergiev
- M.V. Lomonosov Moscow State University, Russia.,Skolkovo Institute of Science and Technology, Moscow, Russia
| | - Olga A Dontsova
- M.V. Lomonosov Moscow State University, Russia.,Skolkovo Institute of Science and Technology, Moscow, Russia
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