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Schultz SK, Kothe U. RNA modifying enzymes shape tRNA biogenesis and function. J Biol Chem 2024; 300:107488. [PMID: 38908752 PMCID: PMC11301382 DOI: 10.1016/j.jbc.2024.107488] [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: 02/23/2024] [Revised: 06/11/2024] [Accepted: 06/12/2024] [Indexed: 06/24/2024] Open
Abstract
Transfer RNAs (tRNAs) are the most highly modified cellular RNAs, both with respect to the proportion of nucleotides that are modified within the tRNA sequence and with respect to the extraordinary diversity in tRNA modification chemistry. However, the functions of many different tRNA modifications are only beginning to emerge. tRNAs have two general clusters of modifications. The first cluster is within the anticodon stem-loop including several modifications essential for protein translation. The second cluster of modifications is within the tRNA elbow, and roles for these modifications are less clear. In general, tRNA elbow modifications are typically not essential for cell growth, but nonetheless several tRNA elbow modifications have been highly conserved throughout all domains of life. In addition to forming modifications, many tRNA modifying enzymes have been demonstrated or hypothesized to also play an important role in folding tRNA acting as tRNA chaperones. In this review, we summarize the known functions of tRNA modifying enzymes throughout the lifecycle of a tRNA molecule, from transcription to degradation. Thereby, we describe how tRNA modification and folding by tRNA modifying enzymes enhance tRNA maturation, tRNA aminoacylation, and tRNA function during protein synthesis, ultimately impacting cellular phenotypes and disease.
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Affiliation(s)
- Sarah K Schultz
- Department of Chemistry, University of Manitoba, Winnipeg, Manitoba, Canada; Alberta RNA Research and Training Institute (ARRTI), Department of Chemistry and Biochemistry, University of Lethbridge, Lethbridge, Alberta, Canada.
| | - Ute Kothe
- Department of Chemistry, University of Manitoba, Winnipeg, Manitoba, Canada; Alberta RNA Research and Training Institute (ARRTI), Department of Chemistry and Biochemistry, University of Lethbridge, Lethbridge, Alberta, Canada.
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Hou J, Li Q, Wang J, Lu W. tRFs and tRNA Halves: Novel Cellular Defenders in Multiple Biological Processes. Curr Issues Mol Biol 2022; 44:5949-5962. [PMID: 36547066 PMCID: PMC9777342 DOI: 10.3390/cimb44120405] [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: 10/27/2022] [Revised: 11/17/2022] [Accepted: 11/23/2022] [Indexed: 11/29/2022] Open
Abstract
tRNA fragments derived from angiogenin or Dicer cleavage are referred to as tRNA-derived fragments (tRFs) and tRNA halves. tRFs and tRNA halves have been identified in both eukaryotes and prokaryotes and are precisely cleaved at specific sites on either precursor or mature tRNA transcripts rather than via random degradation. tRFs and tRNA halves are highly involved in regulating transcription and translation in a canonical or non-canonical manner in response to cellular stress. In this review, we summarize the biogenesis and types of tRFs and tRNA halves, clarify the biological functions and molecular mechanisms of tRNA fragments in both physiological and pathological processes with a particular focus on their cytoprotective roles in defending against oxidation and apoptosis, and highlight their potential application as biomarkers in determining cell fate.
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Affiliation(s)
- Jiani Hou
- Jilin Provincial International Joint Research Center of Animal Breeding & Reproduction Technology, Jilin Agricultural University, Changchun 130118, China
- Key Lab of the Animal Production, Product Quality and Security, Ministry of Education, Jilin Agricultural University, Changchun 130118, China
- College of Animal Science and Technology, Jilin Agricultural University, Changchun 130118, China
| | - Qianqing Li
- Jilin Provincial International Joint Research Center of Animal Breeding & Reproduction Technology, Jilin Agricultural University, Changchun 130118, China
- Key Lab of the Animal Production, Product Quality and Security, Ministry of Education, Jilin Agricultural University, Changchun 130118, China
- College of Animal Science and Technology, Jilin Agricultural University, Changchun 130118, China
| | - Jun Wang
- Jilin Provincial International Joint Research Center of Animal Breeding & Reproduction Technology, Jilin Agricultural University, Changchun 130118, China
- Key Lab of the Animal Production, Product Quality and Security, Ministry of Education, Jilin Agricultural University, Changchun 130118, China
- College of Animal Science and Technology, Jilin Agricultural University, Changchun 130118, China
- Correspondence: (J.W.); (W.L.); Tel.: +86-0431-84533525; Fax: +861-0431-84533525
| | - Wenfa Lu
- Jilin Provincial International Joint Research Center of Animal Breeding & Reproduction Technology, Jilin Agricultural University, Changchun 130118, China
- Key Lab of the Animal Production, Product Quality and Security, Ministry of Education, Jilin Agricultural University, Changchun 130118, China
- College of Animal Science and Technology, Jilin Agricultural University, Changchun 130118, China
- Correspondence: (J.W.); (W.L.); Tel.: +86-0431-84533525; Fax: +861-0431-84533525
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Wen JT, Huang ZH, Li QH, Chen X, Qin HL, Zhao Y. Research progress on the tsRNA classification, function, and application in gynecological malignant tumors. Cell Death Discov 2021; 7:388. [PMID: 34907180 PMCID: PMC8671397 DOI: 10.1038/s41420-021-00789-2] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Revised: 11/18/2021] [Accepted: 11/29/2021] [Indexed: 12/21/2022] Open
Abstract
A large number of small non-coding RNAs derived from tRNAs, called tRNA-derived small RNA (tsRNAs), have been identified by high-throughput RNA sequencing of cell lines. Further research has revealed that they are not produced via random tRNA degradation, but through degradation by specific nuclease cleavages, such as Elac Ribonuclease Z 2 (ELAC2)/RNase Z, RNase L, Dicer, and angiogenin (ANG), the tsRNAs can be classified into the following types based on the location from which they have been derived from the parental tRNA: tRF-1s, tRF-3s, tRF-5s, tiRNA, and tRF-2s/i-tRFs. Moreover, tsRNAs are a type of small RNAs with diverse functions, including gene expression regulation, anti-apoptosis, translation inhibition, participation in epigenetic regulation, initial virus reverse transcription, promote virus replication and cell-to-cell communication. Certain types of tsRNAs are overexpressed in cancer tissues, but are underexpressed in normal tissues. Therefore, the relationship between tsRNAs and the occurrence and development of cancer has attracted significant research attention. Research advancements have contributed to further discoveries of the biological activities of tsRNAs, but the mechanisms of their biogenesis and functions have not been fully elucidated. This article reviews the classification and biological functions of tsRNAs, and introduces the research progress in gynecological malignancies.
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Affiliation(s)
- Jing-Tao Wen
- Department of Obstetrics and Gynecology, Department of Gynecologic Oncology Research Office, Key Laboratory for Major Obstetric Diseases of Guangdong Province, The Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, 510150, China
| | - Zheng-Hao Huang
- Department of Obstetrics and Gynecology, Department of Gynecologic Oncology Research Office, Key Laboratory for Major Obstetric Diseases of Guangdong Province, The Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, 510150, China
| | - Qian-Hui Li
- Department of Obstetrics and Gynecology, Department of Gynecologic Oncology Research Office, Key Laboratory for Major Obstetric Diseases of Guangdong Province, The Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, 510150, China
| | - Xi Chen
- Department of Obstetrics and Gynecology, Department of Gynecologic Oncology Research Office, Key Laboratory for Major Obstetric Diseases of Guangdong Province, The Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, 510150, China
| | - Hong-Lei Qin
- Department of Obstetrics and Gynecology, Department of Gynecologic Oncology Research Office, Key Laboratory for Major Obstetric Diseases of Guangdong Province, The Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, 510150, China
| | - Yang Zhao
- Department of Obstetrics and Gynecology, Department of Gynecologic Oncology Research Office, Key Laboratory for Major Obstetric Diseases of Guangdong Province, The Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, 510150, China.
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Post-Transcriptional Modifications of Conserved Nucleotides in the T-Loop of tRNA: A Tale of Functional Convergent Evolution. Genes (Basel) 2021; 12:genes12020140. [PMID: 33499018 PMCID: PMC7912444 DOI: 10.3390/genes12020140] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Revised: 01/18/2021] [Accepted: 01/20/2021] [Indexed: 12/30/2022] Open
Abstract
The high conservation of nucleotides of the T-loop, including their chemical identity, are hallmarks of tRNAs from organisms belonging to the three Domains of Life. These structural characteristics allow the T-loop to adopt a peculiar intraloop conformation able to interact specifically with other conserved residues of the D-loop, which ultimately folds the mature tRNA in a unique functional canonical L-shaped architecture. Paradoxically, despite the high conservation of modified nucleotides in the T-loop, enzymes catalyzing their formation depend mostly on the considered organism, attesting for an independent but convergent evolution of the post-transcriptional modification processes. The driving force behind this is the preservation of a native conformation of the tRNA elbow that underlies the various interactions of tRNA molecules with different cellular components.
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7-Methylguanosine Modifications in Transfer RNA (tRNA). Int J Mol Sci 2018; 19:ijms19124080. [PMID: 30562954 PMCID: PMC6320965 DOI: 10.3390/ijms19124080] [Citation(s) in RCA: 129] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Revised: 12/05/2018] [Accepted: 12/13/2018] [Indexed: 01/15/2023] Open
Abstract
More than 90 different modified nucleosides have been identified in tRNA. Among the tRNA modifications, the 7-methylguanosine (m7G) modification is found widely in eubacteria, eukaryotes, and a few archaea. In most cases, the m7G modification occurs at position 46 in the variable region and is a product of tRNA (m7G46) methyltransferase. The m7G46 modification forms a tertiary base pair with C13-G22, and stabilizes the tRNA structure. A reaction mechanism for eubacterial tRNA m7G methyltransferase has been proposed based on the results of biochemical, bioinformatic, and structural studies. However, an experimentally determined mechanism of methyl-transfer remains to be ascertained. The physiological functions of m7G46 in tRNA have started to be determined over the past decade. For example, tRNA m7G46 or tRNA (m7G46) methyltransferase controls the amount of other tRNA modifications in thermophilic bacteria, contributes to the pathogenic infectivity, and is also associated with several diseases. In this review, information of tRNA m7G modifications and tRNA m7G methyltransferases is summarized and the differences in reaction mechanism between tRNA m7G methyltransferase and rRNA or mRNA m7G methylation enzyme are discussed.
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Ohira T, Suzuki T. Precursors of tRNAs are stabilized by methylguanosine cap structures. Nat Chem Biol 2016; 12:648-55. [PMID: 27348091 DOI: 10.1038/nchembio.2117] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2015] [Accepted: 05/20/2016] [Indexed: 01/30/2023]
Abstract
Efficient maturation of transfer RNAs (tRNAs) is required for rapid cell growth. However, the precise timing of tRNA processing in coordination with the order of tRNA modifications has not been thoroughly elucidated. To analyze the modification status of tRNA precursors (pre-tRNAs) during maturation, we isolated pre-tRNAs at various stages from Saccharomyces cerevisiae and subjected them to MS analysis. We detected methylated guanosine cap structures at the 5' termini of pre-tRNAs bearing 5' leader sequences. These capped pre-tRNAs accumulated substantially after inhibition of RNase P activity. Upon depletion of the capping enzyme Ceg1p, the steady state level of capped pre-tRNA was markedly reduced. In addition, a population of capped pre-tRNAs accumulated in strains in which 5' exonucleases were inhibited, indicating that the 5' cap structures protect pre-tRNAs from 5'-exonucleolytic degradation during maturation.
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Affiliation(s)
- Takayuki Ohira
- Department of Chemistry and Biotechnology, Graduate School of Engineering, University of Tokyo, Tokyo, Japan
| | - Tsutomu Suzuki
- Department of Chemistry and Biotechnology, Graduate School of Engineering, University of Tokyo, Tokyo, Japan
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Kumar P, Anaya J, Mudunuri SB, Dutta A. Meta-analysis of tRNA derived RNA fragments reveals that they are evolutionarily conserved and associate with AGO proteins to recognize specific RNA targets. BMC Biol 2014; 12:78. [PMID: 25270025 PMCID: PMC4203973 DOI: 10.1186/s12915-014-0078-0] [Citation(s) in RCA: 414] [Impact Index Per Article: 41.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2014] [Accepted: 09/18/2014] [Indexed: 02/07/2023] Open
Abstract
Background tRFs, 14 to 32 nt long single-stranded RNA derived from mature or precursor tRNAs, are a recently discovered class of small RNA that have been found to be present in diverse organisms at read counts comparable to miRNAs. Currently, there is a debate about their biogenesis and function. Results This is the first meta-analysis of tRFs. Analysis of more than 50 short RNA libraries has revealed that tRFs are precisely generated fragments present in all domains of life (bacteria to humans), and are not produced by the miRNA biogenesis pathway. Human PAR-CLIP data shows a striking preference for tRF-5s and tRF-3s to associate with AGO1, 3 and 4 rather than AGO2, and analysis of positional T to C mutational frequency indicates these tRFs associate with Argonautes in a manner similar to miRNAs. The reverse complements of canonical seed positions in these sequences match cross-link centered regions, suggesting these tRF-5s and tRF-3s interact with RNAs in the cell. Consistent with these results, human AGO1 CLASH data contains thousands of tRF-5 and tRF-3 reads chimeric with mRNAs. Conclusions tRFs are an abundant class of small RNA present in all domains of life whose biogenesis is distinct from miRNAs. In human HEK293 cells tRFs associate with Argonautes 1, 3 and 4 and not Argonaute 2 which is the main effector protein of miRNA function, but otherwise have very similar properties to miRNAs, indicating tRFs may play a major role in RNA silencing. Electronic supplementary material The online version of this article (doi:10.1186/s12915-014-0078-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
| | | | | | - Anindya Dutta
- Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville 22901, VA, USA.
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Liao JY, Ma LM, Guo YH, Zhang YC, Zhou H, Shao P, Chen YQ, Qu LH. Deep sequencing of human nuclear and cytoplasmic small RNAs reveals an unexpectedly complex subcellular distribution of miRNAs and tRNA 3' trailers. PLoS One 2010; 5:e10563. [PMID: 20498841 PMCID: PMC2871053 DOI: 10.1371/journal.pone.0010563] [Citation(s) in RCA: 232] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2010] [Accepted: 04/19/2010] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND MicroRNAs (miRNAs) are approximately 22-nt small non-coding regulatory RNAs that have generally been considered to regulate gene expression at the post-transcriptional level in the cytoplasm. However, recent studies have reported that some miRNAs localize to and function in the nucleus. METHODOLOGY/PRINCIPAL FINDINGS To determine the number of miRNAs localized to the nucleus, we systematically investigated the subcellular distribution of small RNAs (sRNAs) by independent deep sequencing sequenced of the nuclear and cytoplasmic pools of 18- to 30-nucleotide sRNAs from human cells. We identified 339 nuclear and 324 cytoplasmic known miRNAs, 300 of which overlap, suggesting that the majority of miRNAs are imported into the nucleus. With the exception of a few miRNAs evidently enriched in the nuclear pool, such as the mir-29b, the ratio of miRNA abundances in the nuclear fraction versus in the cytoplasmic fraction vary to some extent. Moreover, our results revealed that a large number of tRNA 3' trailers are exported from the nucleus and accumulate in the cytoplasm. These tRNA 3' trailers accumulate in a variety of cell types, implying that the biogenesis of tRNA 3' trailers is conserved and that they have a potential functional role in vertebrate cells. CONCLUSION/SIGNIFICANCE Our results provide the first comprehensive view of the subcellular distribution of diverse sRNAs and new insights into the roles of miRNAs and tRNA 3' trailers in the cell.
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Affiliation(s)
- Jian-You Liao
- State Key Laboratory of Biocontrol, Key Laboratory of Gene Engineering of the Ministry of Education, Sun Yat-sen University, Guangzhou, People's Republic of China
| | - Li-Ming Ma
- State Key Laboratory of Biocontrol, Key Laboratory of Gene Engineering of the Ministry of Education, Sun Yat-sen University, Guangzhou, People's Republic of China
| | - Yan-Hua Guo
- State Key Laboratory of Biocontrol, Key Laboratory of Gene Engineering of the Ministry of Education, Sun Yat-sen University, Guangzhou, People's Republic of China
| | - Yu-Chan Zhang
- State Key Laboratory of Biocontrol, Key Laboratory of Gene Engineering of the Ministry of Education, Sun Yat-sen University, Guangzhou, People's Republic of China
| | - Hui Zhou
- State Key Laboratory of Biocontrol, Key Laboratory of Gene Engineering of the Ministry of Education, Sun Yat-sen University, Guangzhou, People's Republic of China
| | - Peng Shao
- State Key Laboratory of Biocontrol, Key Laboratory of Gene Engineering of the Ministry of Education, Sun Yat-sen University, Guangzhou, People's Republic of China
| | - Yue-Qin Chen
- State Key Laboratory of Biocontrol, Key Laboratory of Gene Engineering of the Ministry of Education, Sun Yat-sen University, Guangzhou, People's Republic of China
| | - Liang-Hu Qu
- State Key Laboratory of Biocontrol, Key Laboratory of Gene Engineering of the Ministry of Education, Sun Yat-sen University, Guangzhou, People's Republic of China
- * E-mail:
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Lee YS, Shibata Y, Malhotra A, Dutta A. A novel class of small RNAs: tRNA-derived RNA fragments (tRFs). Genes Dev 2009; 23:2639-49. [PMID: 19933153 DOI: 10.1101/gad.1837609] [Citation(s) in RCA: 805] [Impact Index Per Article: 53.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
New types of small RNAs distinct from microRNAs (miRNAs) are progressively being discovered in various organisms. In order to discover such novel small RNAs, a library of 17- to 26-base-long RNAs was created from prostate cancer cell lines and sequenced by ultra-high-throughput sequencing. A significant number of the sequences are derived from precise processing at the 5' or 3' end of mature or precursor tRNAs to form three series of tRFs (tRNA-derived RNA fragments): the tRF-5, tRF-3, and tRF-1 series. These sequences constitute a class of short RNAs that are second most abundant to miRNAs. Northern hybridization, quantitative RT-PCR, and splinted ligation assays independently measured the levels of at least 17 tRFs. To demonstrate the biological importance of tRFs, we further investigated tRF-1001, derived from the 3' end of a Ser-TGA tRNA precursor transcript that is not retained in the mature tRNA. tRF-1001 is expressed highly in a wide range of cancer cell lines but much less in tissues, and its expression in cell lines was tightly correlated with cell proliferation. siRNA-mediated knockdown of tRF-1001 impaired cell proliferation with the specific accumulation of cells in G2, phenotypes that were reversed specifically by cointroducing a synthetic 2'-O-methyl tRF-1001 oligoribonucleotide resistant to the siRNA. tRF-1001 is generated in the cytoplasm by tRNA 3'-endonuclease ELAC2, a prostate cancer susceptibility gene. Our data suggest that tRFs are not random by-products of tRNA degradation or biogenesis, but an abundant and novel class of short RNAs with precise sequence structure that have specific expression patterns and specific biological roles.
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Affiliation(s)
- Yong Sun Lee
- Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, Virginia 22908, USA
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Matsumoto K, Toyooka T, Tomikawa C, Ochi A, Takano Y, Takayanagi N, Endo Y, Hori H. RNA recognition mechanism of eukaryote tRNA (m7G46) methyltransferase (Trm8-Trm82 complex). FEBS Lett 2007; 581:1599-604. [PMID: 17382321 DOI: 10.1016/j.febslet.2007.03.023] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2007] [Revised: 03/05/2007] [Accepted: 03/09/2007] [Indexed: 01/26/2023]
Abstract
Yeast tRNA (m(7)G46) methyltransferase contains two protein subunits (Trm8 and Trm82). To address the RNA recognition mechanism of the Trm8-Trm82 complex, we investigated methyl acceptance activities of eight truncated yeast tRNA(Phe) transcripts. Both the D-stem and T-stem structures were required for efficient methyl-transfer. To clarify the role of the D-stem structure, we tested four mutant transcripts, in which tertiary base pairs were disrupted. The tertiary base pairs were important but not essential for the methyl-transfer to yeast tRNA(Phe) transcript, suggesting that these base pairs support the induced fit of the G46 base into the catalytic pocket.
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Affiliation(s)
- Keisuke Matsumoto
- Department of Applied Chemistry, Faculty of Engineering, Ehime University, Bunkyo 3, Matsuyama 790-8577, Japan
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Pratt-Hyatt MJ, Kapadia KM, Wilson TE, Engelke DR. Increased recombination between active tRNA genes. DNA Cell Biol 2006; 25:359-64. [PMID: 16792506 PMCID: PMC3756803 DOI: 10.1089/dna.2006.25.359] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Transfer RNA genes are distributed throughout eukaryotic genomes, and are frequently found as multicopy families. In Saccharomyces cerevisiae, tRNA gene transcription by RNA polymerase III suppresses nearby transcription by RNA polymerase II, partially because the tRNA genes are clustered near the nucleolus. We have tested whether active transcription of tRNA genes might also suppress recombination, since recombination between identical copies of the repetitive tRNA genes could delete intervening genes and be detrimental to survival. The opposite proved to be the case. Recombination between active tRNA genes was elevated, but only when both genes are transcribed. We also tested the effects of tRNA genes on recombination between the direct terminal repeats of a neighboring retrotransposon, since most Ty retrotransposons reside next to tRNA genes, and the selective advantage of this arrangement is not known.
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Affiliation(s)
- Matthew J Pratt-Hyatt
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, 48109-0606, USA
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12
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Okamoto H, Watanabe K, Ikeuchi Y, Suzuki T, Endo Y, Hori H. Substrate tRNA Recognition Mechanism of tRNA (m7G46) Methyltransferase from Aquifex aeolicus. J Biol Chem 2004; 279:49151-9. [PMID: 15358762 DOI: 10.1074/jbc.m408209200] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Transfer RNA (m7G46) methyltransferase catalyzes the methyl transfer from S-adenosylmethionine to N7 atom of the guanine 46 residue in tRNA. Analysis of the Aquifex aeolicus genome revealed one candidate open reading frame, aq065, encoding this gene. The aq065 protein was expressed in Escherichia coli and purified to homogeneity on 15% SDS-polyacrylamide gel electrophoresis. Although the overall amino acid sequence of the aq065 protein differs considerably from that of E. coli YggH, the purified aq065 protein possessed a tRNA (m7G46) methyltransferase activity. The modified nucleoside and its location were determined by liquid chromatography-mass spectroscopy. To clarify the RNA recognition mechanism of the enzyme, we investigated the methyl transfer activity to 28 variants of yeast tRNAPhe and E. coli tRNAThr. It was confirmed that 5'-leader and 3'-trailer RNAs of tRNA precursor are not required for the methyl transfer. We found that the enzyme specificity was critically dependent on the size of the variable loop. Experiments using truncated variants showed that the variable loop sequence inserted between two stems is recognized as a substrate, and the most important recognition site is contained within the T stem. These results indicate that the L-shaped tRNA structure is not required for methyl acceptance activity. It was also found that nucleotide substitutions around G46 in three-dimensional core decrease the activity.
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Affiliation(s)
- Hironori Okamoto
- Department of Applied Chemistry, Faculty of Engineering, Ehime University, Bunkyo 3, Matsuyama, 790-8577, Japan
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Nagano M, Shiokawa K. Inhibition of transcription of class II, but not class III and I, genes in Xenopus postblastular embryos overexpressed with the TBP-binding protein, Dr1 (NC2beta). Biochem Biophys Res Commun 1999; 265:644-51. [PMID: 10600475 DOI: 10.1006/bbrc.1999.1722] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Dr1 (NC2beta) is known to effectively repress transcription of class II genes, and much less effectively class III genes, but not class I genes through its binding to the TATA-binding protein (TBP), which is the major component of the basal transcription factor for polymerases II, III, and I. Previously, we isolated Xenopus Dr1 cDNA, and demonstrated that its mRNA is transcribed in oocytes and is inherited into early embryos, but its level decreases in later stages. Here, we overexpressed Xenopus Dr1 in Xenopus embryos and, found that the overexpression significantly reduces the levels of poly(A), cytoskeletal actin and histone H4 mRNAs, and the labeling of heterogeneous mRNA-like RNA in postblastular embryos, without affecting tRNA and rRNA syntheses. These results indicate that the overexpressed Dr1 specifically down-regulates the transcription of class II, but not class III and I, genes, and suggest that Dr1 plays an important role in the control of transcription in Xenopus embryogenesis.
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Affiliation(s)
- M Nagano
- Laboratory of Molecular Embryology, Department of Biological Sciences, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
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14
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Chu WM, Ballard R, Carpick BW, Williams BR, Schmid CW. Potential Alu function: regulation of the activity of double-stranded RNA-activated kinase PKR. Mol Cell Biol 1998; 18:58-68. [PMID: 9418853 PMCID: PMC121451 DOI: 10.1128/mcb.18.1.58] [Citation(s) in RCA: 148] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/1997] [Accepted: 10/13/1997] [Indexed: 02/05/2023] Open
Abstract
Cell stress, viral infection, and translational inhibition increase the abundance of human Alu RNA, suggesting that the level of these transcripts is sensitive to the translational state of the cell. To determine whether Alu RNA functions in translational homeostasis, we investigated its role in the regulation of double-stranded RNA-activated kinase PKR. We found that overexpression of Alu RNA by cotransient transfection increased the expression of a reporter construct, which is consistent with an inhibitory effect on PKR. Alu RNA formed stable, discrete complexes with PKR in vitro, bound PKR in vivo, and antagonized PKR activation both in vitro and in vivo. Alu RNAs produced by either overexpression or exposure of cells to heat shock bound PKR, whereas transiently overexpressed Alu RNA antagonized virus-induced activation of PKR in vivo. Cycloheximide treatment of cells decreased PKR activity, coincident with an increase in Alu RNA. These observations suggest that the increased levels of Alu RNAs caused by cellular exposure to different stresses regulate protein synthesis by antagonizing PKR activation. This provides a functional role for mammalian short interspersed elements, prototypical junk DNA.
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Affiliation(s)
- W M Chu
- Department of Chemistry, University of California, Davis 95616, USA
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15
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Chu WM, Wang Z, Roeder RG, Schmid CW. RNA polymerase III transcription repressed by Rb through its interactions with TFIIIB and TFIIIC2. J Biol Chem 1997; 272:14755-61. [PMID: 9169441 DOI: 10.1074/jbc.272.23.14755] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The retinoblastoma susceptibility gene product (Rb) generally represses RNA polymerase III (Pol III)-directed transcription. This implies that Rb interacts with essential transcription factors. Mutations in either the A or B subdomains in the Rb pocket interfere with Rb-mediated repression of Pol III-directed transcription, which indicates that both subdomains are directly involved in this activity. Addition of either purified TFIIIB or purified TFIIIC2 partially relieves Rb-mediated repression and restores activity to nuclear extracts that had been depleted of essential factors by binding to Rb. Pull down and coimmunoprecipitation experiments as well as functional assays indicate that Rb interacts with both TFIIIB and TFIIIC2 and that the A subdomain is primarily required for binding TFIIIB and the B subdomain for binding TFIIIC2. While Rb interacts with both factors, the A subdomain is more important than the B subdomain in directing Rb-mediated repression, and TFIIIB is the principal target of that activity.
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Affiliation(s)
- W M Chu
- Section of Molecular and Cellular Biology, University of California, Davis, Davis, California 95616, USA
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16
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Grosjean H, Droogmans L, Giégé R, Uhlenbeck OC. Guanosine modifications in runoff transcripts of synthetic transfer RNA-Phe genes microinjected into Xenopus oocytes. BIOCHIMICA ET BIOPHYSICA ACTA 1990; 1050:267-73. [PMID: 2207154 DOI: 10.1016/0167-4781(90)90179-6] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
We have investigated whether unmodified yeast phenylalanine transfer RNA as well as one of its precursors containing an intron of nineteen nucleotides in the anticodon (pre-tRNA-Phe) can become substrates for selected tRNA modification enzymes present in a eukaryotic cell. This study was done by microinjecting into the cytoplasm of Xenopus laevis oocytes transcripts completely deprived of the naturally occurring modified nucleotides; these were obtained in vitro from appropriate synthetic genes under the control of bacteriophage T7 promoter. During the in vitro transcription, 32P labels were introduced with the guanosine triphosphate thus allowing easy detection of guanosine modifications in tRNA by two-dimensional chromatography after complete digestion into 5'-mononucleotides by nuclease P1. Results indicate that modifications occur on five guanosines (at positions 10, 26, 34, 37 and 46) in yeast tRNA-Phe and only on three guanosines (at 10, 26 and 46) in yeast precursor tRNA-Phe. These are the modifications expected from the known nucleotide sequences of naturally occurring Xenopus and yeast tRNA-Phe, i.e. N2-methyl-G10, N2,N2-dimethyl-G26, 2'-O-methyl-G34, N1-methyl-G37 or Y nucleoside-37 and N7-methyl-G46. The rates of modifications occurring in the two kinds of tRNA-Phe are faster in the intron-less tRNA-Phe than in the intron-containing tRNA-Phe. However quantitative modifications are only observed after as long as 75 h incubation in the oocytes.
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Affiliation(s)
- H Grosjean
- Laboratoire de Biochimie, Institut de Biologie Moléculaire et Cellulaire du CNRS, Strasbourg, France
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17
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Thomann HU, Schmutzler C, Hüdepohl U, Blow M, Gross HJ. Genes, variant genes and pseudogenes of the human tRNA(Val) gene family. Expression and pre-tRNA maturation in vitro. J Mol Biol 1989; 209:505-23. [PMID: 2585499 DOI: 10.1016/0022-2836(89)90590-1] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Nine different members of the human tRNA(Val) gene family have been cloned and characterized. Only four of the genes code for one of the known tRNA(Val) isoacceptors. The remaining five genes carry mutations, which in two cases even affect the normal three-dimensional tRNA structure. Each of the genes is transcribed by polymerase III in a HeLa cell nuclear extract, but their transcription efficiencies differ by up to an order of magnitude. Conserved sequences immediately flanking the structural genes that could serve as extragenic control elements were not detected. However, short sequences in the 5' flanking region of two genes show striking similarity with sequences upstream from two Drosophila melanogaster tRNA(Val) genes. Each of the human tRNA(Val) genes has multiple, i.e. two to four, transcription initiation sites. In most cases, transcription termination is caused by oligo(T) sequences downstream from the structural genes. However, the signal sequences ATCTT and CTTCTT also serve as effective polymerase III transcription terminators. The precursors derived from the four tRNA(Val) genes coding for known isoacceptors and those derived from two mutant genes are processed first at their 3' and subsequently at their 5' ends to yield mature tRNAs. The precursor derived from a third mutant gene is incompletely maturated at its 3' end, presumably as a consequence of base-pairing between 5' and 3' flanking sequences. Finally, precursors encoded by the genes that carry mutations affecting the tRNA tertiary structure are completely resistant to 5' and 3' processing.
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Affiliation(s)
- H U Thomann
- Institut für Biochemie, Bayerische Julius-Maximilians-Universität, Würzburg, Federal Republic of Germany
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18
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Carrara G, Calandra P, Fruscoloni P, Doria M, Tocchini-Valentini GP. Site selection by Xenopus laevis RNAase P. Cell 1989; 58:37-45. [PMID: 2752421 DOI: 10.1016/0092-8674(89)90400-5] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Investigation of the mechanism of cleavage site selection by Xenopus RNAase P reveals that the acceptor stem, a 7 bp helix common to all tRNA precursors, is required for cleavage. We propose that Xenopus RNAase P recognizes conserved features of the mature tRNA and that the cleavage site is selected by measuring the length of the acceptor stem. In support of this, we demonstrate that insertion of 2 bp in the acceptor stem of yeast pre-tRNA(3Leu) relocates the cleavage site 2 bases 3' to the original one. In addition, insertion of 1 bp in the acceptor stem of the end-matured yeast pre-tRNA(Phe) generates an RNAase P cleavage site: the enzyme produces a mature tRNA with the characteristic 7 bp stem and releases one 5' flanking nucleotide. Since it has previously been shown that cleavage sites of the splicing endonuclease are determined by the length of the anticodon stem, RNAase P and the splicing endonuclease apparently use different stems to determine their cutting sites.
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Affiliation(s)
- G Carrara
- Institute of Cell Biology, Consiglio Nazionale delle Ricerche, Rome, Italy
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19
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Grosjean H, De Henau S, Doi T, Yamane A, Ohtsuka E, Ikehara M, Beauchemin N, Nicoghosian K, Cedergren R. The in vivo stability, maturation and aminoacylation of anticodon-substituted Escherichia coli initiator methionine tRNAs. EUROPEAN JOURNAL OF BIOCHEMISTRY 1987; 166:325-32. [PMID: 3301339 DOI: 10.1111/j.1432-1033.1987.tb13518.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
We have constructed eight anticodon-modified Escherichia coli initiator methionine (fMet) tRNAs by insertion of synthetic ribotrinucleotides between two fragments ('half molecules') derived from the initiator tRNA. The trinucleotides, namely CAU (the normal anticodon), CAA, CAC, CAG, GAA, GAC, GAG and GAU, were joined to the 5' and 3' tRNA fragments with T4 RNA ligase. The strategy of reconstruction permitted the insertion of radioactive 32P label between nucleotides 36 and 37. tRNAs were microinjected into the cytoplasm of Xenopus laevis oocytes, and the following properties were evaluated: the stability of these eubacterial tRNA variants in the eukaryotic oocytes; the enzymatic modification of the adenosine at position 37 (3' adjacent to the anticodon) and aminoacylation of the chimeric tRNAs by endogenous oocyte aminoacyl-tRNA synthetases. In contrast to other variants, the two RNAs having CAU and GAU anticodons were stable and underwent quantitative modification at A-37. These results show that the enzyme responsible for the modification of A-37 to N-[N-(9-beta-D-ribofuranosylpurine-6-yl)carbamoyl]threonine (t6A) is present in the cytoplasm of oocytes and is very sensitive to the anticodon environment of the tRNA. Also, these same GAU and CAU anticodon-containing tRNAs are fully aminoacylated with the heterologous oocyte aminoacyl-tRNA synthetases in vivo. During the course of this work we developed a generally applicable assay for the aminoacylation of femtomole amounts of labelled tRNAs.
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20
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Mazabraud A, Scherly D, Müller F, Rungger D, Clarkson SG. Structure and transcription termination of a lysine tRNA gene from Xenopus laevis. J Mol Biol 1987; 195:835-45. [PMID: 2443712 DOI: 10.1016/0022-2836(87)90488-8] [Citation(s) in RCA: 34] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Termination of RNA polymerase III transcripts commonly occurs at clusters of T residues. A T4 tract located 72 base-pairs beyond a lysine tRNA gene from Xenopus laevis serves as an efficient termination site for the tRNA(Lys) precursors synthesized from this gene in homologous cell-free extracts. Nucleotides following this T tract influence the extent of read-through transcription in vitro, but in a way that differs from Xenopus 5 S RNA termination. Only approximately 50% of the transcripts initiated in vitro extend as far as this downstream T cluster. The remainder prematurely terminate at a second T4 tract located within the gene itself. The contrasting behaviour of these two T tracts in injected oocytes indicates that termination can be influenced by more than just RNA polymerase III alone, and that different components may contribute to, or hinder, termination at these sites. Prematurely terminated tRNA(Lys) transcripts are detectable in RNA from ovary tissue but not from a kidney cell line, suggesting that read-through transcription beyond intragenic T clusters can be modulated in vivo.
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Affiliation(s)
- A Mazabraud
- Département de Microbiologie, Centre Médical Universitaire, Genève, Switzerland
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21
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Green GA, Marechal L, Weil JH, Guillemaut P. APhaseolus vulgaris mitochondrial tRNA(Leu) is identical to its cytoplasmic counterpart: sequencing andin vivo transcription of the gene corresponding to the cytoplasmic tRNA(Leu.). PLANT MOLECULAR BIOLOGY 1987; 10:13-19. [PMID: 24277459 DOI: 10.1007/bf00014182] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/1987] [Accepted: 09/03/1987] [Indexed: 06/02/2023]
Abstract
We report here that the sequence ofP. vulgaris mitochondrial and cytoplasmic tRNA(Leu) (NAA) are identical except for a post-transcriptional modification. There is an unidentified modification at the "wobble" position which, from the sequence of the nuclear tRNA(Leu) gene, we identify as a derivative of C. We also show that thisP. vulgaris nuclear gene is functional by demonstrating its transcription in anin vivo eukaryotic transcription system.
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Affiliation(s)
- G A Green
- Institut de Biologie Moléculaire et Cellulaire, Université Louis Pasteur, 15 rue Descartes, 67084, Strasbourg, France
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22
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A dispersed tyrosine tRNA gene from Xenopus laevis with high transcriptional activity in vitro. J Biol Chem 1986. [DOI: 10.1016/s0021-9258(17)42496-3] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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23
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Drabkin HJ, RajBhandary UL. Site-specific mutagenesis on a human initiator methionine tRNA gene within a sequence conserved in all eukaryotic initiator tRNAs and studies of its effects on in vitro transcription. J Biol Chem 1985. [DOI: 10.1016/s0021-9258(18)89062-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
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24
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Sharp SJ, Schaack J, Cooley L, Burke DJ, Söll D. Structure and transcription of eukaryotic tRNA genes. CRC CRITICAL REVIEWS IN BIOCHEMISTRY 1985; 19:107-44. [PMID: 3905254 DOI: 10.3109/10409238509082541] [Citation(s) in RCA: 210] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The availability of cloned tRNA genes and a variety of eukaryotic in vitro transcription systems allowed rapid progress during the past few years in the characterization of signals in the DNA-controlling gene transcription and in the processing of the precurser RNAs formed. This will be the subject matter discussed in this review.
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25
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Hipskind RA, Clarkson SG. 5'-flanking sequences that inhibit in vitro transcription of a xenopus laevis tRNA gene. Cell 1983; 34:881-90. [PMID: 6414719 DOI: 10.1016/0092-8674(83)90545-7] [Citation(s) in RCA: 97] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Two series of deletion mutants have been constructed in the 5'-flanking DNA of a variant methionine tRNA gene of X. laevis. When assayed in homologous cell-free extracts, mutants of both series are expressed at very different levels and they initiate transcription at either or both of the two major sites used by the wild-type gene. No similarities are evident in the 5'-flanking regions of well expressed mutants, but two DNA segments are identified that inhibit transcription. The most inhibitory one, between residues -20 and -12, consists of 9 bp of alternating purines and pyrimidines: TGCGCGTGC. The second has only a weak inhibitory effect when in its normal location from -43 to -32, but it can reduce transcription severely when brought closer to the gene; it is composed of 12 bp of alternating purines and pyrimidines with one residue out of alternation: ATGCACAGCGCA. The composition of these tracts has some possible implications for their conformation, which may account for their inhibition of gene expression.
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26
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Abstract
We have isolated phage M13 clones containing the X. laevis trnamet1 gene, each having one or a few C leads to T transitions in the tRNA coding sequence. Nearly every G-C and C-G base pair in the tDNA has been mutagenized. The importance of these altered nucleotides in transcription by RNA polymerase III has been assessed by injecting the cloned DNAs into frog oocyte nuclei together with alpha-32P-GTP and measuring the synthesis of labeled tRNAmet1. Several G-C and C-G base pairs in the structural gene appear to be major promoter determinants, because when mutated, transcription is reduced 3-fold to 20-fold. Most of these determinants occur between nucleotides 7 to 19 and 49 to 61 in sequence regions highly conserved among eucaryotic as well as procaryotic tRNAs. Several additional G-C and C-G base pairs between these two regions also contribute to promoter activity; their location suggests that a stem-loop structure in the DNA encoding the tRNA's anticodon arm is important for RNA polymerase III promoter function.
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27
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Shastry BS, Ng SY, Roeder RG. Multiple factors involved in the transcription of class III genes in Xenopus laevis. J Biol Chem 1982. [DOI: 10.1016/s0021-9258(18)33611-1] [Citation(s) in RCA: 83] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
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