1
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Stegemann F, Marcus E, Neupert S, Ostrowski S, Mathews DH, Phizicky EM. Schizosaccharomyces pombe pus1 mutants are temperature sensitive due to decay of tRNA Ile(UAU) by the 5'-3' exonuclease Dhp1, primarily targeting the unspliced pre-tRNA. RNA (NEW YORK, N.Y.) 2025; 31:566-584. [PMID: 39848696 PMCID: PMC11912914 DOI: 10.1261/rna.080315.124] [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: 11/06/2024] [Accepted: 01/11/2025] [Indexed: 01/25/2025]
Abstract
The pseudouridylase Pus1 catalyzes pseudouridine (Ψ) formation at multiple uridine residues in tRNAs, and in some snRNAs and mRNAs. Although Pus1 is highly conserved, and mutations are associated with human disease, little is known about eukaryotic Pus1 biology. Here, we show that Schizosaccharomyces pombe pus1Δ mutants are temperature sensitive due to decay of tRNAIle(UAU), as tRNAIle(UAU) levels are reduced, and its overexpression suppresses the defect. We show that tRNAIle(UAU) is degraded by the 5'-3' exonuclease Dhp1 (ortholog of Saccharomyces cerevisiae Rat1), as each of four spontaneous pus1Δ suppressors had dhp1 mutations and restored tRNAIle(UAU) levels, and two suppressors that also restored tRNAIle(UAU) levels had mutations in tol1 (S. cerevisiae MET22 ortholog), predicted to inhibit Dhp1. We show that Pus1 modifies U27, U34, and U36 of tRNAIle(UAU), raising the question about how these modifications prevent decay. Our results suggest that Dhp1 targets unspliced pre-tRNAIle(UAU), as a pus1Δ strain in which the only copy of tRNAIle(UAU) has no intron [tI(UAU)-iΔ] is temperature resistant and undergoes no detectable decay, and the corresponding pus1Δ tI(UAU)-WT strain accumulates unspliced pre-tRNAIle(UAU) Moreover, the predicted exon-intron structure of pre-tRNAIle(UAU) differs from the canonical bulge-helix-loop structure compatible with tRNA splicing, and a pus1Δ tI(UAU)i-var strain with intron mutations predicted to improve exon-intron structure is temperature resistant and undergoes little decay. These results suggest that decay of tRNAIle(UAU) by Dhp1 in pus1Δ strains occurs at the level of unspliced pre-tRNAIle(UAU), implying a substantial role for one or more of the Ψ residues in stabilizing the pre-tRNA structure for splicing.
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Affiliation(s)
- Franziska Stegemann
- Department of Biochemistry and Biophysics, Center for RNA Biology, University of Rochester School of Medicine, Rochester, New York 14642, USA
| | - Erin Marcus
- Department of Biochemistry and Biophysics, Center for RNA Biology, University of Rochester School of Medicine, Rochester, New York 14642, USA
| | - Savanah Neupert
- Department of Biochemistry and Biophysics, Center for RNA Biology, University of Rochester School of Medicine, Rochester, New York 14642, USA
| | - Sarah Ostrowski
- Department of Biochemistry and Biophysics, Center for RNA Biology, University of Rochester School of Medicine, Rochester, New York 14642, USA
| | - David H Mathews
- Department of Biochemistry and Biophysics, Center for RNA Biology, University of Rochester School of Medicine, Rochester, New York 14642, USA
| | - Eric M Phizicky
- Department of Biochemistry and Biophysics, Center for RNA Biology, University of Rochester School of Medicine, Rochester, New York 14642, USA
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2
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Li Z, Iida J, Shiimori M, Okamura K. Exportin-5 binding precedes 5'- and 3'-end processing of tRNA precursors in Drosophila. J Biol Chem 2024; 300:107632. [PMID: 39098529 PMCID: PMC11402290 DOI: 10.1016/j.jbc.2024.107632] [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: 04/15/2024] [Revised: 07/16/2024] [Accepted: 07/26/2024] [Indexed: 08/06/2024] Open
Abstract
Exportin5 (Exp5) is the major miRNA nuclear export factor and recognizes structural features of pre-miRNA hairpins, while it also exports other minihelix-containing RNAs. In Drosophila, Exp5 is suggested to play a major role in tRNA export because the gene encoding the canonical tRNA export factor Exportin-t is missing in its genome. To understand molecular functions of fly Exp5, we studied the Exp5/RNA interactome in the cell line S2R + using the crosslinking and immunoprecipitation (CLIP) technology. The CLIP experiment captured known substrates such as tRNAs and miRNAs and detected candidates of novel Exp5 substrates including various mRNAs and long non-coding RNAs (lncRNAs). Some mRNAs and lncRNAs enriched PAR-CLIP tags compared to their expression levels, suggesting selective binding of Exp5 to them. Intronless mRNAs tended to enrich PAR-CLIP tags; therefore, we proposed that Exp5 might play a role in the export of specific classes of mRNAs/lncRNAs. This result suggested that Drosophila Exp5 might have a wider variety of substrates than initially thought. Surprisingly, Exp5 CLIP reads often contained sequences corresponding to the flanking 5'-leaders and 3'-trailers of tRNAs, which were thought to be removed prior to nuclear export. In fact, we found pre-tRNAs before end-processing were present in the cytoplasm, supporting the idea that tRNA end-processing is a cytoplasmic event. In summary, our results provide a genome-wide list of Exp5 substrate candidates and suggest that flies may lack a mechanism to distinguish pre-tRNAs with or without the flanking sequences.
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Affiliation(s)
- Ze Li
- Graduate School of Science and Technology, Nara Institute of Science and Technology, Ikoma, Nara, Japan
| | - Junko Iida
- Graduate School of Science and Technology, Nara Institute of Science and Technology, Ikoma, Nara, Japan
| | - Masami Shiimori
- Graduate School of Science and Technology, Nara Institute of Science and Technology, Ikoma, Nara, Japan
| | - Katsutomo Okamura
- Graduate School of Science and Technology, Nara Institute of Science and Technology, Ikoma, Nara, Japan; Temasek Life Sciences Laboratory, National University of Singapore, Singapore, Singapore.
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3
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Yuan W, Zhang R, Lyu H, Xiao S, Guo D, Zhang Q, Ali DW, Michalak M, Chen XZ, Zhou C, Tang J. Dysregulation of tRNA methylation in cancer: Mechanisms and targeting therapeutic strategies. Cell Death Discov 2024; 10:327. [PMID: 39019857 PMCID: PMC11254935 DOI: 10.1038/s41420-024-02097-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2024] [Revised: 07/04/2024] [Accepted: 07/09/2024] [Indexed: 07/19/2024] Open
Abstract
tRNA is the RNA type that undergoes the most modifications among known RNA, and in recent years, tRNA methylation has emerged as a crucial process in regulating gene translation. Dysregulation of tRNA abundance occurs in cancer cells, along with increased expression and activity of tRNA methyltransferases to raise the level of tRNA modification and stability. This leads to hijacking of translation and synthesis of multiple proteins associated with tumor proliferation, metastasis, invasion, autophagy, chemotherapy resistance, and metabolic reprogramming. In this review, we provide an overview of current research on tRNA methylation in cancer to clarify its involvement in human malignancies and establish a theoretical framework for future therapeutic interventions targeting tRNA methylation processes.
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Affiliation(s)
- Wenbin Yuan
- National "111" Center for Cellular Regulation and Molecular Pharmaceutics, Key Laboratory of Fermentation Engineering (Ministry of Education), Cooperative Innovation Center of Industrial Fermentation (Ministry of Education & Hubei Province), Hubei Key Laboratory of Industrial Microbiology, School of Life and Health Sciences, Hubei University of Technology, Wuhan, China
| | - Rui Zhang
- National "111" Center for Cellular Regulation and Molecular Pharmaceutics, Key Laboratory of Fermentation Engineering (Ministry of Education), Cooperative Innovation Center of Industrial Fermentation (Ministry of Education & Hubei Province), Hubei Key Laboratory of Industrial Microbiology, School of Life and Health Sciences, Hubei University of Technology, Wuhan, China
| | - Hao Lyu
- National "111" Center for Cellular Regulation and Molecular Pharmaceutics, Key Laboratory of Fermentation Engineering (Ministry of Education), Cooperative Innovation Center of Industrial Fermentation (Ministry of Education & Hubei Province), Hubei Key Laboratory of Industrial Microbiology, School of Life and Health Sciences, Hubei University of Technology, Wuhan, China
| | - Shuai Xiao
- National "111" Center for Cellular Regulation and Molecular Pharmaceutics, Key Laboratory of Fermentation Engineering (Ministry of Education), Cooperative Innovation Center of Industrial Fermentation (Ministry of Education & Hubei Province), Hubei Key Laboratory of Industrial Microbiology, School of Life and Health Sciences, Hubei University of Technology, Wuhan, China
| | - Dong Guo
- National "111" Center for Cellular Regulation and Molecular Pharmaceutics, Key Laboratory of Fermentation Engineering (Ministry of Education), Cooperative Innovation Center of Industrial Fermentation (Ministry of Education & Hubei Province), Hubei Key Laboratory of Industrial Microbiology, School of Life and Health Sciences, Hubei University of Technology, Wuhan, China
| | - Qi Zhang
- National "111" Center for Cellular Regulation and Molecular Pharmaceutics, Key Laboratory of Fermentation Engineering (Ministry of Education), Cooperative Innovation Center of Industrial Fermentation (Ministry of Education & Hubei Province), Hubei Key Laboratory of Industrial Microbiology, School of Life and Health Sciences, Hubei University of Technology, Wuhan, China
| | - Declan William Ali
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
| | - Marek Michalak
- Department of Biochemistry, University of Alberta, Edmonton, AB, Canada
| | - Xing-Zhen Chen
- Membrane Protein Disease Research Group, Department of Physiology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
| | - Cefan Zhou
- National "111" Center for Cellular Regulation and Molecular Pharmaceutics, Key Laboratory of Fermentation Engineering (Ministry of Education), Cooperative Innovation Center of Industrial Fermentation (Ministry of Education & Hubei Province), Hubei Key Laboratory of Industrial Microbiology, School of Life and Health Sciences, Hubei University of Technology, Wuhan, China.
| | - Jingfeng Tang
- National "111" Center for Cellular Regulation and Molecular Pharmaceutics, Key Laboratory of Fermentation Engineering (Ministry of Education), Cooperative Innovation Center of Industrial Fermentation (Ministry of Education & Hubei Province), Hubei Key Laboratory of Industrial Microbiology, School of Life and Health Sciences, Hubei University of Technology, Wuhan, China.
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Čáp M, Palková Z. Non-Coding RNAs: Regulators of Stress, Ageing, and Developmental Decisions in Yeast? Cells 2024; 13:599. [PMID: 38607038 PMCID: PMC11012152 DOI: 10.3390/cells13070599] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2024] [Revised: 03/19/2024] [Accepted: 03/27/2024] [Indexed: 04/13/2024] Open
Abstract
Cells must change their properties in order to adapt to a constantly changing environment. Most of the cellular sensing and regulatory mechanisms described so far are based on proteins that serve as sensors, signal transducers, and effectors of signalling pathways, resulting in altered cell physiology. In recent years, however, remarkable examples of the critical role of non-coding RNAs in some of these regulatory pathways have been described in various organisms. In this review, we focus on all classes of non-coding RNAs that play regulatory roles during stress response, starvation, and ageing in different yeast species as well as in structured yeast populations. Such regulation can occur, for example, by modulating the amount and functional state of tRNAs, rRNAs, or snRNAs that are directly involved in the processes of translation and splicing. In addition, long non-coding RNAs and microRNA-like molecules are bona fide regulators of the expression of their target genes. Non-coding RNAs thus represent an additional level of cellular regulation that is gradually being uncovered.
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Affiliation(s)
- Michal Čáp
- Department of Genetics and Microbiology, Faculty of Science, Charles University, BIOCEV, 128 00 Prague, Czech Republic
| | - Zdena Palková
- Department of Genetics and Microbiology, Faculty of Science, Charles University, BIOCEV, 128 00 Prague, Czech Republic
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5
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Yim MK, Stuart CJ, Pond MI, van Hoof A, Johnson SJ. Conserved Residues at the Mtr4 C-Terminus Coordinate Helicase Activity and Exosome Interactions. Biochemistry 2024; 63:159-170. [PMID: 38085597 PMCID: PMC10984559 DOI: 10.1021/acs.biochem.3c00401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2024]
Abstract
Mtr4 is an essential RNA helicase involved in nuclear RNA processing and degradation and is a member of the Ski2-like helicase family. Ski2-like helicases share a common core architecture that includes two RecA-like domains, a winged helix, and a helical bundle (HB) domain. In Mtr4, a short C-terminal tail immediately follows the HB domain and is positioned at the interface of the RecA-like domains. The tail ends with a SLYΦ sequence motif that is highly conserved in a subset of Ski2-like helicases. Here, we show that this sequence is critical for Mtr4 function. Mutations in the C-terminus result in decreased RNA unwinding activity. Mtr4 is a key activator of the RNA exosome complex, and mutations in the SLYΦ motif produce a slow growth phenotype when combined with a partial exosome defect in S. cerevisiae, suggesting an important role of the C-terminus of Mtr4 and the RNA exosome. We further demonstrate that C-terminal mutations impair RNA degradation activity by the major RNA exosome nuclease Rrp44 in vitro. These data demonstrate a role for the Mtr4 C-terminus in regulating helicase activity and coordinating Mtr4-exosome interactions.
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Affiliation(s)
- Matthew K. Yim
- Department of Chemistry and Biochemistry, Utah State University, Logan, UT, 84322, USA
| | - Catherine J. Stuart
- Department of Microbiology and Molecular Genetics, University of Texas Health Science Center at Houston, Houston, Texas, 77030, USA
| | - Markell I. Pond
- Department of Chemistry and Biochemistry, Utah State University, Logan, UT, 84322, USA
| | - Ambro van Hoof
- Department of Microbiology and Molecular Genetics, University of Texas Health Science Center at Houston, Houston, Texas, 77030, USA
| | - Sean J. Johnson
- Department of Chemistry and Biochemistry, Utah State University, Logan, UT, 84322, USA
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6
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De Zoysa T, Hauke AC, Iyer NR, Marcus E, Ostrowski SM, Stegemann F, Ermolenko DN, Fay JC, Phizicky EM. A connection between the ribosome and two S. pombe tRNA modification mutants subject to rapid tRNA decay. PLoS Genet 2024; 20:e1011146. [PMID: 38295128 PMCID: PMC10861057 DOI: 10.1371/journal.pgen.1011146] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2023] [Revised: 02/12/2024] [Accepted: 01/22/2024] [Indexed: 02/02/2024] Open
Abstract
tRNA modifications are crucial in all organisms to ensure tRNA folding and stability, and accurate translation. In both the yeast Saccharomyces cerevisiae and the evolutionarily distant yeast Schizosaccharomyces pombe, mutants lacking certain tRNA body modifications (outside the anticodon loop) are temperature sensitive due to rapid tRNA decay (RTD) of a subset of hypomodified tRNAs. Here we show that for each of two S. pombe mutants subject to RTD, mutations in ribosomal protein genes suppress the temperature sensitivity without altering tRNA levels. Prior work showed that S. pombe trm8Δ mutants, lacking 7-methylguanosine, were temperature sensitive due to RTD, and that one class of suppressors had mutations in the general amino acid control (GAAC) pathway, which was activated concomitant with RTD, resulting in further tRNA loss. We now find that another class of S. pombe trm8Δ suppressors have mutations in rpl genes, encoding 60S subunit proteins, and that suppression occurs with minimal restoration of tRNA levels and reduced GAAC activation. Furthermore, trm8Δ suppression extends to other mutations in the large or small ribosomal subunit. We also find that S. pombe tan1Δ mutants, lacking 4-acetylcytidine, are temperature sensitive due to RTD, that one class of suppressors have rpl mutations, associated with minimal restoration of tRNA levels, and that suppression extends to other rpl and rps mutations. However, although S. pombe tan1Δ temperature sensitivity is associated with some GAAC activation, suppression by an rpl mutation only modestly inhibits GAAC activation. We propose a model in which ribosomal protein mutations result in reduced ribosome concentrations, leading to both reduced ribosome collisions and a reduced requirement for tRNA, with these effects having different relative importance in trm8Δ and tan1Δ mutants. This model is consistent with our results in S. cerevisiae trm8Δ trm4Δ mutants, known to undergo RTD, fueling speculation that this model applies across eukaryotes.
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Affiliation(s)
- Thareendra De Zoysa
- Department of Biochemistry and Biophysics, Center for RNA Biology, University of Rochester School of Medicine, Rochester, New York, United States of America
| | - Alayna C. Hauke
- Department of Biochemistry and Biophysics, Center for RNA Biology, University of Rochester School of Medicine, Rochester, New York, United States of America
| | - Nivedita R. Iyer
- Department of Biochemistry and Biophysics, Center for RNA Biology, University of Rochester School of Medicine, Rochester, New York, United States of America
| | - Erin Marcus
- Department of Biochemistry and Biophysics, Center for RNA Biology, University of Rochester School of Medicine, Rochester, New York, United States of America
| | - Sarah M. Ostrowski
- Department of Biochemistry and Biophysics, Center for RNA Biology, University of Rochester School of Medicine, Rochester, New York, United States of America
| | - Franziska Stegemann
- Department of Biochemistry and Biophysics, Center for RNA Biology, University of Rochester School of Medicine, Rochester, New York, United States of America
| | - Dmitri N. Ermolenko
- Department of Biochemistry and Biophysics, Center for RNA Biology, University of Rochester School of Medicine, Rochester, New York, United States of America
| | - Justin C. Fay
- Department of Biology, University of Rochester, Rochester, New York, United States of America
| | - Eric M. Phizicky
- Department of Biochemistry and Biophysics, Center for RNA Biology, University of Rochester School of Medicine, Rochester, New York, United States of America
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7
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De Zoysa T, Hauke AC, Iyer NR, Marcus E, Ostrowski SM, Fay JC, Phizicky EM. A connection between the ribosome and two S. pombe tRNA modification mutants subject to rapid tRNA decay. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.18.558340. [PMID: 37790432 PMCID: PMC10542129 DOI: 10.1101/2023.09.18.558340] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/05/2023]
Abstract
tRNA modifications are crucial in all organisms to ensure tRNA folding and stability, and accurate translation in the ribosome. In both the yeast Saccharomyces cerevisiae and the evolutionarily distant yeast Schizosaccharomyces pombe, mutants lacking certain tRNA body modifications (outside the anticodon loop) are temperature sensitive due to rapid tRNA decay (RTD) of a subset of hypomodified tRNAs. Here we show that for each of two S. pombe mutants subject to RTD, mutations in ribosomal protein genes suppress the temperature sensitivity without altering tRNA levels. Prior work showed that S. pombe trm8Δ mutants, lacking 7-methylguanosine, were temperature sensitive due to RTD and that one class of suppressors had mutations in the general amino acid control (GAAC) pathway, which was activated concomitant with RTD, resulting in further tRNA loss. We now find that another class of S. pombe trm8Δ suppressors have mutations in rpl genes, encoding 60S subunit proteins, and that suppression occurs with minimal restoration of tRNA levels and reduced GAAC activation. Furthermore, trm8Δ suppression extends to other mutations in the large or small ribosomal subunit. We also find that S. pombe tan1Δ mutants, lacking 4-acetylcytidine, are temperature sensitive due to RTD, that one class of suppressors have rpl mutations, associated with minimal restoration of tRNA levels, and that suppression extends to other rpl and rps mutations. However, although S. pombe tan1Δ temperature sensitivity is associated with some GAAC activation, suppression by an rpl mutation does not significantly inhibit GAAC activation. These results suggest that ribosomal protein mutations suppress the temperature sensitivity of S. pombe trm8Δ and tan1Δ mutants due to reduced ribosome concentrations, leading to both a reduced requirement for tRNA, and reduced ribosome collisions and GAAC activation. Results with S. cerevisiae trm8Δ trm4Δ mutants are consistent with this model, and fuel speculation that similar results will apply across eukaryotes.
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Affiliation(s)
- Thareendra De Zoysa
- Department of Biochemistry and Biophysics, Center for RNA Biology, University of Rochester School of Medicine, Rochester, NY, USA 14642
| | - Alayna C. Hauke
- Department of Biochemistry and Biophysics, Center for RNA Biology, University of Rochester School of Medicine, Rochester, NY, USA 14642
| | - Nivedita R. Iyer
- Department of Biochemistry and Biophysics, Center for RNA Biology, University of Rochester School of Medicine, Rochester, NY, USA 14642
| | - Erin Marcus
- Department of Biochemistry and Biophysics, Center for RNA Biology, University of Rochester School of Medicine, Rochester, NY, USA 14642
| | - Sarah M. Ostrowski
- Department of Biochemistry and Biophysics, Center for RNA Biology, University of Rochester School of Medicine, Rochester, NY, USA 14642
| | - Justin C. Fay
- Department of Biology, University of Rochester, Rochester, NY, USA 14627
| | - Eric M. Phizicky
- Department of Biochemistry and Biophysics, Center for RNA Biology, University of Rochester School of Medicine, Rochester, NY, USA 14642
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8
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Khreiss A, Bohnsack KE, Bohnsack MT. Molecular functions of RNA helicases during ribosomal subunit assembly. Biol Chem 2023; 404:781-789. [PMID: 37233600 DOI: 10.1515/hsz-2023-0135] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Accepted: 05/09/2023] [Indexed: 05/27/2023]
Abstract
During their biogenesis, the ribosomal subunits undergo numerous structural and compositional changes to achieve their final architecture. RNA helicases are a key driving force of such remodelling events but deciphering their particular functions has long been challenging due to lack of knowledge of their molecular functions and RNA substrates. Advances in the biochemical characterisation of RNA helicase activities together with new insights into RNA helicase binding sites on pre-ribosomes and structural snapshots of pre-ribosomal complexes containing RNA helicases now open the door to a deeper understanding of precisely how different RNA helicases contribute to ribosomal subunit maturation.
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Affiliation(s)
- Ali Khreiss
- Department of Molecular Biology, University Medical Center Göttingen, Humboldtallee 23, D-37073 Göttingen, Germany
| | - Katherine E Bohnsack
- Department of Molecular Biology, University Medical Center Göttingen, Humboldtallee 23, D-37073 Göttingen, Germany
| | - Markus T Bohnsack
- Department of Molecular Biology, University Medical Center Göttingen, Humboldtallee 23, D-37073 Göttingen, Germany
- Göttingen Centre for Molecular Biosciences, Georg-August University, Justus-von-Liebig-Weg 11, D-37077 Göttingen, Germany
- Max Planck Institute for Multidisciplinary Sciences, Am Fassberg 11, D-37077 Göttingen, Germany
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9
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Tasak M, Phizicky EM. Initiator tRNA lacking 1-methyladenosine is targeted by the rapid tRNA decay pathway in evolutionarily distant yeast species. PLoS Genet 2022; 18:e1010215. [PMID: 35901126 PMCID: PMC9362929 DOI: 10.1371/journal.pgen.1010215] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Revised: 08/09/2022] [Accepted: 07/05/2022] [Indexed: 11/18/2022] Open
Abstract
All tRNAs have numerous modifications, lack of which often results in growth defects in the budding yeast Saccharomyces cerevisiae and neurological or other disorders in humans. In S. cerevisiae, lack of tRNA body modifications can lead to impaired tRNA stability and decay of a subset of the hypomodified tRNAs. Mutants lacking 7-methylguanosine at G46 (m7G46), N2,N2-dimethylguanosine (m2,2G26), or 4-acetylcytidine (ac4C12), in combination with other body modification mutants, target certain mature hypomodified tRNAs to the rapid tRNA decay (RTD) pathway, catalyzed by 5’-3’ exonucleases Xrn1 and Rat1, and regulated by Met22. The RTD pathway is conserved in the phylogenetically distant fission yeast Schizosaccharomyces pombe for mutants lacking m7G46. In contrast, S. cerevisiae trm6/gcd10 mutants with reduced 1-methyladenosine (m1A58) specifically target pre-tRNAiMet(CAU) to the nuclear surveillance pathway for 3’-5’ exonucleolytic decay by the TRAMP complex and nuclear exosome. We show here that the RTD pathway has an unexpected major role in the biology of m1A58 and tRNAiMet(CAU) in both S. pombe and S. cerevisiae. We find that S. pombe trm6Δ mutants lacking m1A58 are temperature sensitive due to decay of tRNAiMet(CAU) by the RTD pathway. Thus, trm6Δ mutants had reduced levels of tRNAiMet(CAU) and not of eight other tested tRNAs, overexpression of tRNAiMet(CAU) restored growth, and spontaneous suppressors that restored tRNAiMet(CAU) levels had mutations in dhp1/RAT1 or tol1/MET22. In addition, deletion of cid14/TRF4 in the nuclear surveillance pathway did not restore growth. Furthermore, re-examination of S. cerevisiae trm6 mutants revealed a major role of the RTD pathway in maintaining tRNAiMet(CAU) levels, in addition to the known role of the nuclear surveillance pathway. These findings provide evidence for the importance of m1A58 in the biology of tRNAiMet(CAU) throughout eukaryotes, and fuel speculation that the RTD pathway has a major role in quality control of body modification mutants throughout fungi and other eukaryotes.
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Affiliation(s)
- Monika Tasak
- Department of Biochemistry and Biophysics, Center for RNA Biology, University of Rochester School of Medicine, Rochester, New York, United States of America
| | - Eric M. Phizicky
- Department of Biochemistry and Biophysics, Center for RNA Biology, University of Rochester School of Medicine, Rochester, New York, United States of America
- * E-mail:
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10
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Jin H, Huo C, Zhou T, Xie S. m 1A RNA Modification in Gene Expression Regulation. Genes (Basel) 2022; 13:910. [PMID: 35627295 PMCID: PMC9141559 DOI: 10.3390/genes13050910] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Revised: 05/17/2022] [Accepted: 05/18/2022] [Indexed: 01/31/2023] Open
Abstract
N1-methyladenosine (m1A) is a prevalent and reversible post-transcriptional RNA modification that decorates tRNA, rRNA and mRNA. Recent studies based on technical advances in analytical chemistry and high-throughput sequencing methods have revealed the crucial roles of m1A RNA modification in gene regulation and biological processes. In this review, we focus on progress in the study of m1A methyltransferases, m1A demethylases and m1A-dependent RNA-binding proteins and highlight the biological mechanisms and functions of m1A RNA modification, as well as its association with human disease. We also summarize the current understanding of detection approaches for m1A RNA modification.
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Affiliation(s)
- Hao Jin
- The Children’s Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou 310052, China;
- Department of Cell Biology, Zhejiang University School of Medicine, Hangzhou 310058, China;
| | - Chunxiao Huo
- Department of Cell Biology, Zhejiang University School of Medicine, Hangzhou 310058, China;
| | - Tianhua Zhou
- Department of Cell Biology, Zhejiang University School of Medicine, Hangzhou 310058, China;
- Cancer Center, Zhejiang University, Hangzhou 310058, China
| | - Shanshan Xie
- The Children’s Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou 310052, China;
- Department of Cell Biology, Zhejiang University School of Medicine, Hangzhou 310058, China;
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11
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Zhang N, Olsen KJ, Ball D, Johnson SJ, D’Arcy S. OUP accepted manuscript. Nucleic Acids Res 2022; 50:4042-4053. [PMID: 35380691 PMCID: PMC9023267 DOI: 10.1093/nar/gkac170] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Revised: 03/01/2022] [Accepted: 04/01/2022] [Indexed: 11/13/2022] Open
Affiliation(s)
| | | | - Darby Ball
- Department of Chemistry and Biochemistry, The University of Texas at Dallas, Richardson, TX75080, USA
| | - Sean J Johnson
- Correspondence may also be addressed to Sean J. Johnson.
| | - Sheena D’Arcy
- To whom correspondence should be addressed. Tel: +1 972 883 2915;
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12
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Using hydrogen-deuterium exchange mass spectrometry to characterize Mtr4 interactions with RNA. Methods Enzymol 2022; 673:475-516. [PMID: 35965017 DOI: 10.1016/bs.mie.2022.04.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Hydrogen deuterium exchange coupled to mass spectrometry (HDX-MS) is a valuable technique to investigate the dynamics of protein systems. The approach compares the deuterium uptake of protein backbone amides under multiple conditions to characterize protein conformation and interaction. HDX-MS is versatile and can be applied to diverse ligands, however, challenges remain when it comes to exploring complexes containing nucleic acids. In this chapter, we present procedures for the optimization and application of HDX-MS to studying RNA-binding proteins and use the RNA helicase Mtr4 as a demonstrative example. We highlight considerations in designing on-exchange, bottom-up, comparative studies on proteins with RNA. Our protocol details preliminary testing and optimization of experimental parameters. Difficulties arising from the inclusion of RNA, such as signal repression and sample carryover, are addressed. We discuss how chromatography parameters can be adjusted depending on the issues presented by the RNA, emphasizing reproducible peptide recovery in the absence and presence of RNA. Methods for visualization of HDX data integrated with statistical analysis are also reviewed with examples. These protocols can be applied to future studies of various RNA-protein complexes.
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13
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Yim MK, Denson JM, Gold MD, Johnson SJ. Purification and characterization of Mtr4 and TRAMP from S. cerevisiae. Methods Enzymol 2022; 673:425-451. [DOI: 10.1016/bs.mie.2022.03.042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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14
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Das M, Zattas D, Zinder JC, Wasmuth EV, Henri J, Lima CD. Substrate discrimination and quality control require each catalytic activity of TRAMP and the nuclear RNA exosome. Proc Natl Acad Sci U S A 2021; 118:e2024846118. [PMID: 33782132 PMCID: PMC8040639 DOI: 10.1073/pnas.2024846118] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Quality control requires discrimination between functional and aberrant species to selectively target aberrant substrates for destruction. Nuclear RNA quality control in Saccharomyces cerevisiae includes the TRAMP complex that marks RNA for decay via polyadenylation followed by helicase-dependent 3' to 5' degradation by the RNA exosome. Using reconstitution biochemistry, we show that polyadenylation and helicase activities of TRAMP cooperate with processive and distributive exoribonuclease activities of the nuclear RNA exosome to protect stable RNA from degradation while selectively targeting and degrading less stable RNA. Substrate discrimination is lost when the distributive exoribonuclease activity of Rrp6 is inactivated, leading to degradation of stable and unstable RNA species. These data support a proofreading mechanism in which deadenylation by Rrp6 competes with Mtr4-dependent degradation to protect stable RNA while selectively targeting and degrading unstable RNA.
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Affiliation(s)
- Mom Das
- Structural Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, New York, NY 10065
| | - Dimitrios Zattas
- Structural Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, New York, NY 10065
| | - John C Zinder
- Structural Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, New York, NY 10065
- Tri-Institutional Training Program in Chemical Biology, Memorial Sloan Kettering Cancer Center, New York, NY 10065
| | - Elizabeth V Wasmuth
- Structural Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, New York, NY 10065
| | - Julien Henri
- Structural Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, New York, NY 10065
| | - Christopher D Lima
- Structural Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, New York, NY 10065;
- HHMI, Memorial Sloan Kettering Cancer Center, New York, NY 10065
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15
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Helicase-Dependent RNA Decay Illuminated by a Cryo-EM Structure of a Human Nuclear RNA Exosome-MTR4 Complex. Cell 2019; 173:1663-1677.e21. [PMID: 29906447 DOI: 10.1016/j.cell.2018.05.041] [Citation(s) in RCA: 110] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Revised: 04/26/2018] [Accepted: 05/17/2018] [Indexed: 01/08/2023]
Abstract
The ribonucleolytic RNA exosome interacts with RNA helicases to degrade RNA. To understand how the 3' to 5' Mtr4 helicase engages RNA and the nuclear exosome, we reconstituted 14-subunit Mtr4-containing RNA exosomes from Saccharomyces cerevisiae, Schizosaccharomyces pombe, and human and show that they unwind structured substrates to promote degradation. We loaded a human exosome with an optimized DNA-RNA chimera that stalls MTR4 during unwinding and determined its structure to an overall resolution of 3.45 Å by cryoelectron microscopy (cryo-EM). The structure reveals an RNA-engaged helicase atop the non-catalytic core, with RNA captured within the central channel and DIS3 exoribonuclease active site. MPP6 tethers MTR4 to the exosome through contacts to the RecA domains of MTR4. EXOSC10 remains bound to the core, but its catalytic module and cofactor C1D are displaced by RNA-engaged MTR4. Competition for the exosome core may ensure that RNA is committed to degradation by DIS3 when engaged by MTR4.
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16
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Structural basis for MTR4-ZCCHC8 interactions that stimulate the MTR4 helicase in the nuclear exosome-targeting complex. Proc Natl Acad Sci U S A 2018; 115:E5506-E5515. [PMID: 29844170 PMCID: PMC6004480 DOI: 10.1073/pnas.1803530115] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Aberrant or unwanted transcripts can be degraded by the RNA exosome with the help of the nuclear exosome-targeting (NEXT) complex. NEXT, composed of RNA-binding protein RBM7, scaffold ZCCHC8, and helicase MTR4, is implicated in stress response, neurodegeneration, and viral ribogenesis. Here, we characterize the activities of NEXT that support its role in exosome-mediated decay. NEXT catalyzes 3′→5′ helicase activity and disrupts RNA:RNA and DNA:RNA duplexes more efficiently than MTR4. Optimal activity is observed when substrates include a uridine-rich motif, for interactions with RBM7, and a 3′ poly(A) tail. The ZCCHC8 C-terminal domain binds the helicase core and can stimulate MTR4 helicase/ATPase activities. Our results highlight the interplay among NEXT subunits to ensure effective targeting of substrates. The nuclear exosome-targeting (NEXT) complex functions as an RNA exosome cofactor and is involved in surveillance and turnover of aberrant transcripts and noncoding RNAs. NEXT is a ternary complex composed of the RNA-binding protein RBM7, the scaffold zinc-knuckle protein ZCCHC8, and the helicase MTR4. While RNA interactions with RBM7 are known, it remains unclear how NEXT subunits collaborate to recognize and prepare substrates for degradation. Here, we show that MTR4 helicase activity is enhanced when associated with RBM7 and ZCCHC8. While uridine-rich substrates interact with RBM7 and are preferred, optimal activity is observed when substrates include a polyadenylated 3′ end. We identify a bipartite interaction of ZCCHC8 with MTR4 and uncover a role for the conserved C-terminal domain of ZCCHC8 in stimulating MTR4 helicase and ATPase activities. A crystal structure reveals that the ZCCHC8 C-terminal domain binds the helicase core in a manner that is distinct from that observed for Saccharomyces cerevisiae exosome cofactors Trf4p and Air2p. Our results are consistent with a model whereby effective targeting of substrates by NEXT entails recognition of elements within the substrate and activation of MTR4 helicase activity.
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Abstract
The nuclear RNA exosome is an essential and versatile machinery that regulates maturation and degradation of a huge plethora of RNA species. The past two decades have witnessed remarkable progress in understanding the whole picture of its RNA substrates and the structural basis of its functions. In addition to the exosome itself, recent studies focusing on associated co-factors have been elucidating how the exosome is directed towards specific substrates. Moreover, it has been gradually realized that loss-of-function of exosome subunits affect multiple biological processes such as the DNA damage response, R-loop resolution, maintenance of genome integrity, RNA export, translation and cell differentiation. In this review, we summarize the current knowledge of the mechanisms of nuclear exosome-mediated RNA metabolism and discuss their physiological significance.
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18
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Han J, van Hoof A. The RNA Exosome Channeling and Direct Access Conformations Have Distinct In Vivo Functions. Cell Rep 2018; 16:3348-3358. [PMID: 27653695 DOI: 10.1016/j.celrep.2016.08.059] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Revised: 06/06/2016] [Accepted: 08/18/2016] [Indexed: 10/21/2022] Open
Abstract
The RNA exosome is a 3'-5' ribonuclease complex that is composed of nine core subunits and an essential catalytic subunit, Rrp44. Two distinct conformations of Rrp44 were revealed in previous structural studies, suggesting that Rrp44 may change its conformation to exert its function. In the channeling conformation, (Rrp44(ch)), RNA accesses the active site after traversing the central channel of the RNA exosome, whereas in the other conformation, (Rrp44(da)), RNA gains direct access to the active site. Here, we show that the Rrp44(da) exosome is important for nuclear function of the RNA exosome. Defects caused by disrupting the direct access conformation are distinct from those caused by channel-occluding mutations, indicating specific functions for each conformation. Our genetic analyses provide in vivo evidence that the RNA exosome employs a direct-access route to recruit specific substrates, indicating that the RNA exosome uses alternative conformations to act on different RNA substrates.
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Affiliation(s)
- Jaeil Han
- Department of Microbiology and Molecular Genetics, University of Texas Health Science Center at Houston, 6431 Fannin Street, MSB 1.212, Houston, TX 77030, USA; The University of Texas Graduate School of Biomedical Sciences, University of Texas Health Science Center at Houston, 6431 Fannin Street, MSB 1.212, Houston, TX 77030, USA
| | - Ambro van Hoof
- Department of Microbiology and Molecular Genetics, University of Texas Health Science Center at Houston, 6431 Fannin Street, MSB 1.212, Houston, TX 77030, USA; The University of Texas Graduate School of Biomedical Sciences, University of Texas Health Science Center at Houston, 6431 Fannin Street, MSB 1.212, Houston, TX 77030, USA.
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19
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Abstract
Numerous surveillance pathways sculpt eukaryotic transcriptomes by degrading unneeded, defective, and potentially harmful noncoding RNAs (ncRNAs). Because aberrant and excess ncRNAs are largely degraded by exoribonucleases, a key characteristic of these RNAs is an accessible, protein-free 5' or 3' end. Most exoribonucleases function with cofactors that recognize ncRNAs with accessible 5' or 3' ends and/or increase the availability of these ends. Noncoding RNA surveillance pathways were first described in budding yeast, and there are now high-resolution structures of many components of the yeast pathways and significant mechanistic understanding as to how they function. Studies in human cells are revealing the ways in which these pathways both resemble and differ from their yeast counterparts, and are also uncovering numerous pathways that lack equivalents in budding yeast. In this review, we describe both the well-studied pathways uncovered in yeast and the new concepts that are emerging from studies in mammalian cells. We also discuss the ways in which surveillance pathways compete with chaperone proteins that transiently protect nascent ncRNA ends from exoribonucleases, with partner proteins that sequester these ends within RNPs, and with end modification pathways that protect the ends of some ncRNAs from nucleases.
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Affiliation(s)
- Cedric Belair
- RNA Biology Laboratory, Center for Cancer Research, National Cancer Institute , National Institutes of Health , Frederick , Maryland 21702 , United States
| | - Soyeong Sim
- RNA Biology Laboratory, Center for Cancer Research, National Cancer Institute , National Institutes of Health , Frederick , Maryland 21702 , United States
| | - Sandra L Wolin
- RNA Biology Laboratory, Center for Cancer Research, National Cancer Institute , National Institutes of Health , Frederick , Maryland 21702 , United States
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20
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Fan J, Kuai B, Wu G, Wu X, Chi B, Wang L, Wang K, Shi Z, Zhang H, Chen S, He Z, Wang S, Zhou Z, Li G, Cheng H. Exosome cofactor hMTR4 competes with export adaptor ALYREF to ensure balanced nuclear RNA pools for degradation and export. EMBO J 2017; 36:2870-2886. [PMID: 28801509 DOI: 10.15252/embj.201696139] [Citation(s) in RCA: 80] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2016] [Revised: 07/21/2017] [Accepted: 07/23/2017] [Indexed: 12/20/2022] Open
Abstract
The exosome is a key RNA machine that functions in the degradation of unwanted RNAs. Here, we found that significant fractions of precursors and mature forms of mRNAs and long noncoding RNAs are degraded by the nuclear exosome in normal human cells. Exosome-mediated degradation of these RNAs requires its cofactor hMTR4. Significantly, hMTR4 plays a key role in specifically recruiting the exosome to its targets. Furthermore, we provide several lines of evidence indicating that hMTR4 executes this role by directly competing with the mRNA export adaptor ALYREF for associating with ARS2, a component of the cap-binding complex (CBC), and this competition is critical for determining whether an RNA is degraded or exported to the cytoplasm. Together, our results indicate that the competition between hMTR4 and ALYREF determines exosome recruitment and functions in creating balanced nuclear RNA pools for degradation and export.
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Affiliation(s)
- Jing Fan
- State Key Laboratory of Molecular Biology, Shanghai Key Laboratory of Molecular Andrology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Bin Kuai
- State Key Laboratory of Molecular Biology, Shanghai Key Laboratory of Molecular Andrology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Guifen Wu
- State Key Laboratory of Molecular Biology, Shanghai Key Laboratory of Molecular Andrology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Xudong Wu
- Laboratory of Molecular Modeling and Design, State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China
| | - Binkai Chi
- State Key Laboratory of Molecular Biology, Shanghai Key Laboratory of Molecular Andrology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Lantian Wang
- State Key Laboratory of Molecular Biology, Shanghai Key Laboratory of Molecular Andrology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Ke Wang
- State Key Laboratory of Molecular Biology, Shanghai Key Laboratory of Molecular Andrology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Zhubing Shi
- State Key Laboratory of Molecular Biology, Shanghai Key Laboratory of Molecular Andrology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Heng Zhang
- State Key Laboratory of Molecular Biology, Shanghai Key Laboratory of Molecular Andrology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - She Chen
- National Institute of Biological Sciences, Beijing, China
| | - Zhisong He
- CAS Key Laboratory of Computational Biology, CAS-MPG Partner Institute for Computational Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Siyuan Wang
- State Key Laboratory of Molecular Biology, Shanghai Key Laboratory of Molecular Andrology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Zhaocai Zhou
- State Key Laboratory of Molecular Biology, Shanghai Key Laboratory of Molecular Andrology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Guohui Li
- Laboratory of Molecular Modeling and Design, State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China
| | - Hong Cheng
- State Key Laboratory of Molecular Biology, Shanghai Key Laboratory of Molecular Andrology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
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21
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Pearce SF, Rorbach J, Haute LV, D’Souza AR, Rebelo-Guiomar P, Powell CA, Brierley I, Firth AE, Minczuk M. Maturation of selected human mitochondrial tRNAs requires deadenylation. eLife 2017; 6:e27596. [PMID: 28745585 PMCID: PMC5544427 DOI: 10.7554/elife.27596] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2017] [Accepted: 07/21/2017] [Indexed: 02/02/2023] Open
Abstract
Human mitochondria contain a genome (mtDNA) that encodes essential subunits of the oxidative phosphorylation system. Expression of mtDNA entails multi-step maturation of precursor RNA. In other systems, the RNA life cycle involves surveillance mechanisms, however, the details of RNA quality control have not been extensively characterised in human mitochondria. Using a mitochondrial ribosome profiling and mitochondrial poly(A)-tail RNA sequencing (MPAT-Seq) assay, we identify the poly(A)-specific exoribonuclease PDE12 as a major factor for the quality control of mitochondrial non-coding RNAs. The lack of PDE12 results in a spurious polyadenylation of the 3' ends of the mitochondrial (mt-) rRNA and mt-tRNA. While the aberrant adenylation of 16S mt-rRNA did not affect the integrity of the mitoribosome, spurious poly(A) additions to mt-tRNA led to reduced levels of aminoacylated pool of certain mt-tRNAs and mitoribosome stalling at the corresponding codons. Therefore, our data uncover a new, deadenylation-dependent mtRNA maturation pathway in human mitochondria.
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Affiliation(s)
- Sarah F Pearce
- MRC Mitochondrial Biology Unit, University of Cambridge, Cambridge, United Kingdom
| | - Joanna Rorbach
- MRC Mitochondrial Biology Unit, University of Cambridge, Cambridge, United Kingdom
| | - Lindsey Van Haute
- MRC Mitochondrial Biology Unit, University of Cambridge, Cambridge, United Kingdom
| | - Aaron R D’Souza
- MRC Mitochondrial Biology Unit, University of Cambridge, Cambridge, United Kingdom
| | - Pedro Rebelo-Guiomar
- MRC Mitochondrial Biology Unit, University of Cambridge, Cambridge, United Kingdom
- Graduate Program in Areas of Basic and Applied Biology, University of Porto, Porto, Portugal
| | - Christopher A Powell
- MRC Mitochondrial Biology Unit, University of Cambridge, Cambridge, United Kingdom
| | - Ian Brierley
- Department of Pathology, University of Cambridge, Cambridge, United Kingdom
| | - Andrew E Firth
- Department of Pathology, University of Cambridge, Cambridge, United Kingdom
| | - Michal Minczuk
- MRC Mitochondrial Biology Unit, University of Cambridge, Cambridge, United Kingdom
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22
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An Mtr4/ZFC3H1 complex facilitates turnover of unstable nuclear RNAs to prevent their cytoplasmic transport and global translational repression. Genes Dev 2017; 31:1257-1271. [PMID: 28733371 PMCID: PMC5558927 DOI: 10.1101/gad.302604.117] [Citation(s) in RCA: 99] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2017] [Accepted: 06/22/2017] [Indexed: 12/12/2022]
Abstract
Ogami et al. highlight a critical role for Mtr4/ZFC3H1 in nuclear surveillance of naturally unstable lncRNAs to prevent their accumulation, transport to the cytoplasm, and resultant disruption of protein synthesis. Many long noncoding RNAs (lncRNAs) are unstable and rapidly degraded in the nucleus by the nuclear exosome. An exosome adaptor complex called NEXT (nuclear exosome targeting) functions to facilitate turnover of some of these lncRNAs. Here we show that knockdown of one NEXT subunit, Mtr4, but neither of the other two subunits, resulted in accumulation of two types of lncRNAs: prematurely terminated RNAs (ptRNAs) and upstream antisense RNAs (uaRNAs). This suggested a NEXT-independent Mtr4 function, and, consistent with this, we isolated a distinct complex containing Mtr4 and the zinc finger protein ZFC3H1. Strikingly, knockdown of either protein not only increased pt/uaRNA levels but also led to their accumulation in the cytoplasm. Furthermore, all pt/uaRNAs examined associated with active ribosomes, but, paradoxically, this correlated with a global reduction in heavy polysomes and overall repression of translation. Our findings highlight a critical role for Mtr4/ZFC3H1 in nuclear surveillance of naturally unstable lncRNAs to prevent their accumulation, transport to the cytoplasm, and resultant disruption of protein synthesis.
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23
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Transcription by RNA polymerase III: insights into mechanism and regulation. Biochem Soc Trans 2017; 44:1367-1375. [PMID: 27911719 PMCID: PMC5095917 DOI: 10.1042/bst20160062] [Citation(s) in RCA: 76] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2016] [Revised: 07/07/2016] [Accepted: 07/13/2016] [Indexed: 12/13/2022]
Abstract
The highly abundant, small stable RNAs that are synthesized by RNA polymerase III (RNAPIII) have key functional roles, particularly in the protein synthesis apparatus. Their expression is metabolically demanding, and is therefore coupled to changing demands for protein synthesis during cell growth and division. Here, we review the regulatory mechanisms that control the levels of RNAPIII transcripts and discuss their potential physiological relevance. Recent analyses have revealed differential regulation of tRNA expression at all steps on its biogenesis, with significant deregulation of mature tRNAs in cancer cells.
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24
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Tomecki R, Sikorski PJ, Zakrzewska-Placzek M. Comparison of preribosomal RNA processing pathways in yeast, plant and human cells - focus on coordinated action of endo- and exoribonucleases. FEBS Lett 2017; 591:1801-1850. [PMID: 28524231 DOI: 10.1002/1873-3468.12682] [Citation(s) in RCA: 79] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Revised: 05/14/2017] [Accepted: 05/15/2017] [Indexed: 12/17/2022]
Abstract
Proper regulation of ribosome biosynthesis is mandatory for cellular adaptation, growth and proliferation. Ribosome biogenesis is the most energetically demanding cellular process, which requires tight control. Abnormalities in ribosome production have severe consequences, including developmental defects in plants and genetic diseases (ribosomopathies) in humans. One of the processes occurring during eukaryotic ribosome biogenesis is processing of the ribosomal RNA precursor molecule (pre-rRNA), synthesized by RNA polymerase I, into mature rRNAs. It must not only be accurate but must also be precisely coordinated with other phenomena leading to the synthesis of functional ribosomes: RNA modification, RNA folding, assembly with ribosomal proteins and nucleocytoplasmic RNP export. A multitude of ribosome biogenesis factors ensure that these events take place in a correct temporal order. Among them are endo- and exoribonucleases involved in pre-rRNA processing. Here, we thoroughly present a wide spectrum of ribonucleases participating in rRNA maturation, focusing on their biochemical properties, regulatory mechanisms and substrate specificity. We also discuss cooperation between various ribonucleolytic activities in particular stages of pre-rRNA processing, delineating major similarities and differences between three representative groups of eukaryotes: yeast, plants and humans.
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Affiliation(s)
- Rafal Tomecki
- Laboratory of RNA Biology and Functional Genomics, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland.,Department of Genetics and Biotechnology, Faculty of Biology, University of Warsaw, Poland
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25
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Onderak AM, Anderson JT. Loss of the RNA helicase SKIV2L2 impairs mitotic progression and replication-dependent histone mRNA turnover in murine cell lines. RNA (NEW YORK, N.Y.) 2017; 23:910-926. [PMID: 28351885 PMCID: PMC5435864 DOI: 10.1261/rna.060640.117] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/03/2017] [Accepted: 03/02/2017] [Indexed: 06/06/2023]
Abstract
RNA surveillance via the nuclear exosome requires cofactors such as the helicase SKIV2L2 to process and degrade certain noncoding RNAs. This research aimed to characterize the phenotype associated with RNAi knockdown of Skiv2l2 in two murine cancer cell lines: Neuro2A and P19. SKIV2L2 depletion in Neuro2A and P19 cells induced changes in gene expression indicative of cell differentiation and reduced cellular proliferation by 30%. Propidium iodide-based cell-cycle analysis of Skiv2l2 knockdown cells revealed defective progression through the G2/M phase and an accumulation of mitotic cells, suggesting SKIV2L2 contributes to mitotic progression. Since SKIV2L2 targets RNAs to the nuclear exosome for processing and degradation, we identified RNA targets elevated in cells depleted of SKIV2L2 that could account for the observed twofold increase in mitotic cells. Skiv2l2 knockdown cells accumulated replication-dependent histone mRNAs, among other RNAs, that could impede mitotic progression and indirectly trigger differentiation.
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Affiliation(s)
- Alexis M Onderak
- Department of Biological Sciences, Marquette University, Milwaukee, Wisconsin 53201, USA
| | - James T Anderson
- Department of Biological Sciences, Marquette University, Milwaukee, Wisconsin 53201, USA
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26
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Wasmuth EV, Lima CD. The Rrp6 C-terminal domain binds RNA and activates the nuclear RNA exosome. Nucleic Acids Res 2016; 45:846-860. [PMID: 27899565 PMCID: PMC5314766 DOI: 10.1093/nar/gkw1152] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Revised: 10/17/2016] [Accepted: 11/03/2016] [Indexed: 12/14/2022] Open
Abstract
The eukaryotic RNA exosome is an essential, multi-subunit complex that catalyzes RNA turnover, maturation, and quality control processes. Its non-catalytic donut-shaped core includes 9 subunits that associate with the 3′ to 5′ exoribonucleases Rrp6, and Rrp44/Dis3, a subunit that also catalyzes endoribonuclease activity. Although recent structures and biochemical studies of RNA bound exosomes from S. cerevisiae revealed that the Exo9 central channel guides RNA to either Rrp6 or Rrp44 using partially overlapping and mutually exclusive paths, several issues related to RNA recruitment remain. Here, we identify activities for the highly basic Rrp6 C-terminal tail that we term the ‘lasso’ because it binds RNA and stimulates ribonuclease activities associated with Rrp44 and Rrp6 within the 11-subunit nuclear exosome. Stimulation is dependent on the Exo9 central channel, and the lasso contributes to degradation and processing activities of exosome substrates in vitro and in vivo. Finally, we present evidence that the Rrp6 lasso may be a conserved feature of the eukaryotic RNA exosome.
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Affiliation(s)
- Elizabeth V Wasmuth
- Structural Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, USA
| | - Christopher D Lima
- Structural Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, USA .,Howard Hughes Medical Institute, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, USA
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27
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Patrick EM, Srinivasan S, Jankowsky E, Comstock MJ. The RNA helicase Mtr4p is a duplex-sensing translocase. Nat Chem Biol 2016; 13:99-104. [PMID: 27870836 DOI: 10.1038/nchembio.2234] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2016] [Accepted: 09/29/2016] [Indexed: 12/30/2022]
Abstract
The conserved Saccharomyces cerevisiae Ski2-like RNA helicase Mtr4p plays essential roles in eukaryotic nuclear RNA processing. RNA helicase activity of Mtr4p is critical for biological functions of the enzyme, but the molecular basis for RNA unwinding is not understood. Here, single-molecule high-resolution optical trapping measurements reveal that Mtr4p unwinds RNA duplexes by 3'-to-5' translocation on the loading strand, that strand separation occurs in discrete steps of 6 base pairs and that a single Mtr4p molecule performs consecutive unwinding steps. We further show that RNA unwinding by Mtr4p requires interaction with upstream RNA duplex. Inclusion of Mtr4p within the TRAMP complex increases the rate constant for unwinding initiation but does not change the characteristics of Mtr4p's helicase mechanism. Our data indicate that Mtr4p utilizes a previously unknown unwinding mode that combines aspects of canonical translocating helicases and non-canonical duplex-sensing helicases, thereby restricting directional translocation to duplex regions.
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Affiliation(s)
- Eric M Patrick
- Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan, USA
| | - Sukanya Srinivasan
- Center for RNA Molecular Biology and Department of Biochemistry, Case Western University, Cleveland, Ohio, USA
| | - Eckhard Jankowsky
- Center for RNA Molecular Biology and Department of Biochemistry, Case Western University, Cleveland, Ohio, USA
| | - Matthew J Comstock
- Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan, USA
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28
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Liu F, Clark W, Luo G, Wang X, Fu Y, Wei J, Wang X, Hao Z, Dai Q, Zheng G, Ma H, Han D, Evans M, Klungland A, Pan T, He C. ALKBH1-Mediated tRNA Demethylation Regulates Translation. Cell 2016; 167:816-828.e16. [PMID: 27745969 DOI: 10.1016/j.cell.2016.09.038] [Citation(s) in RCA: 346] [Impact Index Per Article: 38.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2016] [Revised: 08/14/2016] [Accepted: 09/22/2016] [Indexed: 12/27/2022]
Abstract
tRNA is a central component of protein synthesis and the cell signaling network. One salient feature of tRNA is its heavily modified status, which can critically impact its function. Here, we show that mammalian ALKBH1 is a tRNA demethylase. It mediates the demethylation of N1-methyladenosine (m1A) in tRNAs. The ALKBH1-catalyzed demethylation of the target tRNAs results in attenuated translation initiation and decreased usage of tRNAs in protein synthesis. This process is dynamic and responds to glucose availability to affect translation. Our results uncover reversible methylation of tRNA as a new mechanism of post-transcriptional gene expression regulation.
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Affiliation(s)
- Fange Liu
- Department of Chemistry, Department of Biochemistry and Molecular Biology, and Institute for Biophysical Dynamics, The University of Chicago, 929 East 57th Street, Chicago, IL 60637, USA; Howard Hughes Medical Institute, The University of Chicago, 929 East 57th Street, Chicago, IL 60637, USA
| | - Wesley Clark
- Department of Biochemistry and Molecular Biology and Institute for Biophysical Dynamics, The University of Chicago, 929 East 57(th) Street, Chicago, IL 60637, USA
| | - Guanzheng Luo
- Department of Chemistry, Department of Biochemistry and Molecular Biology, and Institute for Biophysical Dynamics, The University of Chicago, 929 East 57th Street, Chicago, IL 60637, USA; Howard Hughes Medical Institute, The University of Chicago, 929 East 57th Street, Chicago, IL 60637, USA
| | - Xiaoyun Wang
- Department of Biochemistry and Molecular Biology and Institute for Biophysical Dynamics, The University of Chicago, 929 East 57(th) Street, Chicago, IL 60637, USA
| | - Ye Fu
- Department of Chemistry, Department of Biochemistry and Molecular Biology, and Institute for Biophysical Dynamics, The University of Chicago, 929 East 57th Street, Chicago, IL 60637, USA; Howard Hughes Medical Institute, The University of Chicago, 929 East 57th Street, Chicago, IL 60637, USA
| | - Jiangbo Wei
- Department of Chemistry, Department of Biochemistry and Molecular Biology, and Institute for Biophysical Dynamics, The University of Chicago, 929 East 57th Street, Chicago, IL 60637, USA; Howard Hughes Medical Institute, The University of Chicago, 929 East 57th Street, Chicago, IL 60637, USA
| | - Xiao Wang
- Department of Chemistry, Department of Biochemistry and Molecular Biology, and Institute for Biophysical Dynamics, The University of Chicago, 929 East 57th Street, Chicago, IL 60637, USA; Howard Hughes Medical Institute, The University of Chicago, 929 East 57th Street, Chicago, IL 60637, USA
| | - Ziyang Hao
- Department of Chemistry, Department of Biochemistry and Molecular Biology, and Institute for Biophysical Dynamics, The University of Chicago, 929 East 57th Street, Chicago, IL 60637, USA; Howard Hughes Medical Institute, The University of Chicago, 929 East 57th Street, Chicago, IL 60637, USA
| | - Qing Dai
- Department of Chemistry, Department of Biochemistry and Molecular Biology, and Institute for Biophysical Dynamics, The University of Chicago, 929 East 57th Street, Chicago, IL 60637, USA; Howard Hughes Medical Institute, The University of Chicago, 929 East 57th Street, Chicago, IL 60637, USA
| | - Guanqun Zheng
- Department of Biochemistry and Molecular Biology and Institute for Biophysical Dynamics, The University of Chicago, 929 East 57(th) Street, Chicago, IL 60637, USA
| | - Honghui Ma
- Department of Chemistry, Department of Biochemistry and Molecular Biology, and Institute for Biophysical Dynamics, The University of Chicago, 929 East 57th Street, Chicago, IL 60637, USA; Howard Hughes Medical Institute, The University of Chicago, 929 East 57th Street, Chicago, IL 60637, USA
| | - Dali Han
- Department of Chemistry, Department of Biochemistry and Molecular Biology, and Institute for Biophysical Dynamics, The University of Chicago, 929 East 57th Street, Chicago, IL 60637, USA; Howard Hughes Medical Institute, The University of Chicago, 929 East 57th Street, Chicago, IL 60637, USA
| | - Molly Evans
- Department of Biochemistry and Molecular Biology and Institute for Biophysical Dynamics, The University of Chicago, 929 East 57(th) Street, Chicago, IL 60637, USA
| | - Arne Klungland
- Department of Microbiology, Oslo University Hospital, Rikshospitalet, 0027 Oslo, Norway; Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, 0317 Oslo, Norway
| | - Tao Pan
- Department of Biochemistry and Molecular Biology and Institute for Biophysical Dynamics, The University of Chicago, 929 East 57(th) Street, Chicago, IL 60637, USA.
| | - Chuan He
- Department of Chemistry, Department of Biochemistry and Molecular Biology, and Institute for Biophysical Dynamics, The University of Chicago, 929 East 57th Street, Chicago, IL 60637, USA; Howard Hughes Medical Institute, The University of Chicago, 929 East 57th Street, Chicago, IL 60637, USA; Department of Biochemistry and Molecular Biology and Institute for Biophysical Dynamics, The University of Chicago, 929 East 57(th) Street, Chicago, IL 60637, USA.
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Li Y, Burclaff J, Anderson JT. Mutations in Mtr4 Structural Domains Reveal Their Important Role in Regulating tRNAiMet Turnover in Saccharomyces cerevisiae and Mtr4p Enzymatic Activities In Vitro. PLoS One 2016; 11:e0148090. [PMID: 26820724 PMCID: PMC4731217 DOI: 10.1371/journal.pone.0148090] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2015] [Accepted: 01/12/2016] [Indexed: 12/24/2022] Open
Abstract
RNA processing and turnover play important roles in the maturation, metabolism and quality control of a large variety of RNAs thereby contributing to gene expression and cellular health. The TRAMP complex, composed of Air2p, Trf4p and Mtr4p, stimulates nuclear exosome-dependent RNA processing and degradation in Saccharomyces cerevisiae. The Mtr4 protein structure is composed of a helicase core and a novel so-called arch domain, which protrudes from the core. The helicase core contains highly conserved helicase domains RecA-1 and 2, and two structural domains of unclear functions, winged helix domain (WH) and ratchet domain. How the structural domains (arch, WH and ratchet domain) coordinate with the helicase domains and what roles they are playing in regulating Mtr4p helicase activity are unknown. We created a library of Mtr4p structural domain mutants for the first time and screened for those defective in the turnover of TRAMP and exosome substrate, hypomodified tRNAiMet. We found these domains regulate Mtr4p enzymatic activities differently through characterizing the arch domain mutants K700N and P731S, WH mutant K904N, and ratchet domain mutant R1030G. Arch domain mutants greatly reduced Mtr4p RNA binding, which surprisingly did not lead to significant defects on either in vivo tRNAiMet turnover, or in vitro unwinding activities. WH mutant K904N and Ratchet domain mutant R1030G showed decreased tRNAiMet turnover in vivo, as well as reduced RNA binding, ATPase and unwinding activities of Mtr4p in vitro. Particularly, K904 was found to be very important for steady protein levels in vivo. Overall, we conclude that arch domain plays a role in RNA binding but is largely dispensable for Mtr4p enzymatic activities, however the structural domains in the helicase core significantly contribute to Mtr4p ATPase and unwinding activities.
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Affiliation(s)
- Yan Li
- College of Veterinary Medicine, Agricultural University of Hebei, Baoding, Hebei, 071001, China
| | - Joseph Burclaff
- Division of Biology and Biomedical Sciences, Washington University, St. Louis, MO, 63110, United States of America
| | - James T. Anderson
- Department of Biological Sciences, Marquette University, Milwaukee, WI, 53233, United States of America
- * E-mail:
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30
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Fox MJ, Mosley AL. Rrp6: Integrated roles in nuclear RNA metabolism and transcription termination. WILEY INTERDISCIPLINARY REVIEWS-RNA 2015; 7:91-104. [PMID: 26612606 DOI: 10.1002/wrna.1317] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Revised: 10/02/2015] [Accepted: 10/07/2015] [Indexed: 11/08/2022]
Abstract
The yeast RNA exosome is a eukaryotic ribonuclease complex essential for RNA processing, surveillance, and turnover. It is comprised of a barrel-shaped core and cap as well as a 3'-5' ribonuclease known as Dis3 that contains both endo- and exonuclease domains. A second exonuclease, Rrp6, is added in the nucleus. Dis3 and Rrp6 have both shared and distinct roles in RNA metabolism, and this review will focus primarily on Rrp6 and the roles of the RNA exosome in the nucleus. The functions of the nuclear exosome are modulated by cofactors and interacting partners specific to each type of substrate. Generally, the cofactor TRAMP (Trf4/5-Air2/1-Mtr4 polyadenylation) complex helps unwind unstable RNAs, RNAs requiring processing such as rRNAs, tRNAs, or snRNAs or improperly processed RNAs and direct it toward the exosome. In yeast, Rrp6 interacts with Nrd1, the cap-binding complex, and RNA polymerase II to aid in nascent RNA processing, termination, and polyA tail length regulation. Recent studies have shown that proper termination and processing of short, noncoding RNAs by Rrp6 is particularly important for transcription regulation across the genome and has important implications for regulation of diverse processes at the cellular level. Loss of proper Rrp6 and exosome activity may contribute to various pathologies such as autoimmune disease, neurological disorders, and cancer. WIREs RNA 2016, 7:91-104. doi: 10.1002/wrna.1317 For further resources related to this article, please visit the WIREs website.
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Affiliation(s)
- Melanie J Fox
- Biochemistry and Molecular Biology, Indiana University, Indianapolis, IN, USA
| | - Amber L Mosley
- Biochemistry and Molecular Biology, Indiana University, Indianapolis, IN, USA
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31
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Betat H, Mörl M. The CCA-adding enzyme: A central scrutinizer in tRNA quality control. Bioessays 2015; 37:975-82. [DOI: 10.1002/bies.201500043] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Heike Betat
- Institute for Biochemistry; University of Leipzig; Leipzig Germany
| | - Mario Mörl
- Institute for Biochemistry; University of Leipzig; Leipzig Germany
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32
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Surveillance and cleavage of eukaryotic tRNAs. Int J Mol Sci 2015; 16:1873-93. [PMID: 25599528 PMCID: PMC4307339 DOI: 10.3390/ijms16011873] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Accepted: 01/09/2015] [Indexed: 12/27/2022] Open
Abstract
Beyond their central role in protein synthesis, transfer RNAs (tRNAs) have many other crucial functions. This includes various roles in the regulation of gene expression, stress responses, metabolic processes and priming reverse transcription. In the RNA world, tRNAs are, with ribosomal RNAs, among the most stable molecules. Nevertheless, they are not eternal. As key elements of cell function, tRNAs need to be continuously quality-controlled. Two tRNA surveillance pathways have been identified. They act on hypo-modified or mis-processed pre-tRNAs and on mature tRNAs lacking modifications. A short overview of these two pathways will be presented here. Furthermore, while the exoribonucleases acting in these pathways ultimately lead to complete tRNA degradation, numerous tRNA-derived fragments (tRFs) are present within a cell. These cleavage products of tRNAs now potentially emerge as a new class of small non-coding RNAs (sncRNAs) and are suspected to have important regulatory functions. The tRFs are evolutionarily widespread and created by cleavage at different positions by various endonucleases. Here, we review our present knowledge on the biogenesis and function of tRFs in various organisms.
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33
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Taylor LL, Jackson RN, Rexhepaj M, King AK, Lott LK, van Hoof A, Johnson SJ. The Mtr4 ratchet helix and arch domain both function to promote RNA unwinding. Nucleic Acids Res 2014; 42:13861-72. [PMID: 25414331 PMCID: PMC4267639 DOI: 10.1093/nar/gku1208] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Mtr4 is a conserved Ski2-like RNA helicase and a subunit of the TRAMP complex that activates exosome-mediated 3′-5′ turnover in nuclear RNA surveillance and processing pathways. Prominent features of the Mtr4 structure include a four-domain ring-like helicase core and a large arch domain that spans the core. The ‘ratchet helix’ is positioned to interact with RNA substrates as they move through the helicase. However, the contribution of the ratchet helix in Mtr4 activity is poorly understood. Here we show that strict conservation along the ratchet helix is particularly extensive for Ski2-like RNA helicases compared to related helicases. Mutation of residues along the ratchet helix alters in vitro activity in Mtr4 and TRAMP and causes slow growth phenotypes in vivo. We also identify a residue on the ratchet helix that influences Mtr4 affinity for polyadenylated substrates. Previous work indicated that deletion of the arch domain has minimal effect on Mtr4 unwinding activity. We now show that combining the arch deletion with ratchet helix mutations abolishes helicase activity and produces a lethal in vivo phenotype. These studies demonstrate that the ratchet helix modulates helicase activity and suggest that the arch domain plays a previously unrecognized role in unwinding substrates.
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Affiliation(s)
- Lacy L Taylor
- Department of Chemistry and Biochemistry, Utah State University, Logan, UT 84322-0300, USA
| | - Ryan N Jackson
- Department of Chemistry and Biochemistry, Utah State University, Logan, UT 84322-0300, USA
| | - Megi Rexhepaj
- Department of Chemistry and Biochemistry, Utah State University, Logan, UT 84322-0300, USA
| | - Alejandra Klauer King
- Department of Microbiology and Molecular Genetics, University of Texas Health Science Center-Houston, Houston, TX 77030, USA
| | - Lindsey K Lott
- Department of Chemistry and Biochemistry, Utah State University, Logan, UT 84322-0300, USA
| | - Ambro van Hoof
- Department of Microbiology and Molecular Genetics, University of Texas Health Science Center-Houston, Houston, TX 77030, USA
| | - Sean J Johnson
- Department of Chemistry and Biochemistry, Utah State University, Logan, UT 84322-0300, USA
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34
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Dorweiler JE, Ni T, Zhu J, Munroe SH, Anderson JT. Certain adenylated non-coding RNAs, including 5' leader sequences of primary microRNA transcripts, accumulate in mouse cells following depletion of the RNA helicase MTR4. PLoS One 2014; 9:e99430. [PMID: 24926684 PMCID: PMC4057207 DOI: 10.1371/journal.pone.0099430] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2014] [Accepted: 05/14/2014] [Indexed: 12/30/2022] Open
Abstract
RNA surveillance plays an important role in posttranscriptional regulation. Seminal work in this field has largely focused on yeast as a model system, whereas exploration of RNA surveillance in mammals is only recently begun. The increased transcriptional complexity of mammalian systems provides a wider array of targets for RNA surveillance, and, while many questions remain unanswered, emerging data suggest the nuclear RNA surveillance machinery exhibits increased complexity as well. We have used a small interfering RNA in mouse N2A cells to target the homolog of a yeast protein that functions in RNA surveillance (Mtr4p). We used high-throughput sequencing of polyadenylated RNAs (PA-seq) to quantify the effects of the mMtr4 knockdown (KD) on RNA surveillance. We demonstrate that overall abundance of polyadenylated protein coding mRNAs is not affected, but several targets of RNA surveillance predicted from work in yeast accumulate as adenylated RNAs in the mMtr4KD. microRNAs are an added layer of transcriptional complexity not found in yeast. After Drosha cleavage separates the pre-miRNA from the microRNA's primary transcript, the byproducts of that transcript are generally thought to be degraded. We have identified the 5′ leading segments of pri-miRNAs as novel targets of mMtr4 dependent RNA surveillance.
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Affiliation(s)
- Jane E. Dorweiler
- Department of Biological Sciences, Marquette University, Milwaukee, Wisconsin, United States of America
| | - Ting Ni
- DNA Sequencing and Genomics Core, Genetics and Development Biology Center, National Institutes of Health, National Heart Lung and Blood Institute, Bethesda, Maryland, United States of America
| | - Jun Zhu
- DNA Sequencing and Genomics Core, Genetics and Development Biology Center, National Institutes of Health, National Heart Lung and Blood Institute, Bethesda, Maryland, United States of America
| | - Stephen H. Munroe
- Department of Biological Sciences, Marquette University, Milwaukee, Wisconsin, United States of America
- * E-mail: (JTA); (SHM)
| | - James T. Anderson
- Department of Biological Sciences, Marquette University, Milwaukee, Wisconsin, United States of America
- * E-mail: (JTA); (SHM)
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35
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The RNA helicase FRH is an ATP-dependent regulator of CK1a in the circadian clock of Neurospora crassa. Nat Commun 2014; 5:3598. [PMID: 24710172 DOI: 10.1038/ncomms4598] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2013] [Accepted: 03/10/2014] [Indexed: 11/08/2022] Open
Abstract
The Neurospora clock protein FRQ forms a complex with casein kinase 1a (CK1a) and FRH, a DEAD box-containing RNA helicase with a clock-independent essential function in RNA metabolism. In the course of a circadian period, FRQ is progressively hyperphosphorylated and eventually degraded. Timed hyperphosphorylation of FRQ is crucial for timekeeping of the clock. Here we show that the ATPase activity of FRH attenuates the kinetics of CK1a-mediated hyperphosphorylation of FRQ. Hyperphosphorylation of FRQ is strictly dependent on site-specific recruitment of a CK1a molecule that is activated upon binding. The FRH ATPase cycle regulates the access of CK1a to phosphorylation sites in FRQ in cis, suggesting that FRH is an ATP-dependent remodelling factor acting on the protein complex. We show that the affinity of CK1a for FRQ decreases with increasing FRQ phosphorylation, suggesting functional inactivation of FRQ in the negative feedback loop of the circadian clock before and independent of its degradation.
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36
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Liu JJ, Bratkowski MA, Liu X, Niu CY, Ke A, Wang HW. Visualization of distinct substrate-recruitment pathways in the yeast exosome by EM. Nat Struct Mol Biol 2013; 21:95-102. [PMID: 24336220 PMCID: PMC3976988 DOI: 10.1038/nsmb.2736] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2013] [Accepted: 11/06/2013] [Indexed: 12/25/2022]
Abstract
The eukaryotic exosome is a multi-subunit complex typically composed of a catalytically inactive core and the Rrp44 protein, which contains 3’ to 5’ exo- and endo-ribonuclease activities. RNA substrates have been shown to be recruited through the core to reach Rrp44's exoribonuclease (EXO) site. Using single particle electron microscopy and biochemical analysis, we provide visual evidence that two distinct substrate recruitment pathways exist. In the through-core route, channeling of the single stranded substrates from the core to Rrp44 induces a characteristic conformational change in Rrp44. In the alternative direct-access route, this conformational change does not take place and the RNA substrate is visualized to avoid the core and enter Rrp44's EXO site directly. Our results provide mechanistic explanations for several RNA processing scenarios by the eukaryotic exosome and indicate substrate specific modes of degradation by this complex.
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Affiliation(s)
- Jun-Jie Liu
- Ministry of Education Key Laboratory of Protein Science, Tsinghua-Peking Joint Center for Life Sciences, Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China.,Joint Graduate Program of Peking-Tsinghua-NBIS, Tsinghua University, Beijing 100084, China
| | - Matthew A Bratkowski
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA
| | - Xueqi Liu
- Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Chu-Ya Niu
- Ministry of Education Key Laboratory of Protein Science, Tsinghua-Peking Joint Center for Life Sciences, Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Ailong Ke
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA
| | - Hong-Wei Wang
- Ministry of Education Key Laboratory of Protein Science, Tsinghua-Peking Joint Center for Life Sciences, Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China.,Joint Graduate Program of Peking-Tsinghua-NBIS, Tsinghua University, Beijing 100084, China
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37
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Transfer RNA post-transcriptional processing, turnover, and subcellular dynamics in the yeast Saccharomyces cerevisiae. Genetics 2013; 194:43-67. [PMID: 23633143 DOI: 10.1534/genetics.112.147470] [Citation(s) in RCA: 145] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Transfer RNAs (tRNAs) are essential for protein synthesis. In eukaryotes, tRNA biosynthesis employs a specialized RNA polymerase that generates initial transcripts that must be subsequently altered via a multitude of post-transcriptional steps before the tRNAs beome mature molecules that function in protein synthesis. Genetic, genomic, biochemical, and cell biological approaches possible in the powerful Saccharomyces cerevisiae system have led to exciting advances in our understandings of tRNA post-transcriptional processing as well as to novel insights into tRNA turnover and tRNA subcellular dynamics. tRNA processing steps include removal of transcribed leader and trailer sequences, addition of CCA to the 3' mature sequence and, for tRNA(His), addition of a 5' G. About 20% of yeast tRNAs are encoded by intron-containing genes. The three-step splicing process to remove the introns surprisingly occurs in the cytoplasm in yeast and each of the splicing enzymes appears to moonlight in functions in addition to tRNA splicing. There are 25 different nucleoside modifications that are added post-transcriptionally, creating tRNAs in which ∼15% of the residues are nucleosides other than A, G, U, or C. These modified nucleosides serve numerous important functions including tRNA discrimination, translation fidelity, and tRNA quality control. Mature tRNAs are very stable, but nevertheless yeast cells possess multiple pathways to degrade inappropriately processed or folded tRNAs. Mature tRNAs are also dynamic in cells, moving from the cytoplasm to the nucleus and back again to the cytoplasm; the mechanism and function of this retrograde process is poorly understood. Here, the state of knowledge for tRNA post-transcriptional processing, turnover, and subcellular dynamics is addressed, highlighting the questions that remain.
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38
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Tomecki R, Drazkowska K, Kucinski I, Stodus K, Szczesny RJ, Gruchota J, Owczarek EP, Kalisiak K, Dziembowski A. Multiple myeloma-associated hDIS3 mutations cause perturbations in cellular RNA metabolism and suggest hDIS3 PIN domain as a potential drug target. Nucleic Acids Res 2013; 42:1270-90. [PMID: 24150935 PMCID: PMC3902924 DOI: 10.1093/nar/gkt930] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
hDIS3 is a mainly nuclear, catalytic subunit of the human exosome complex, containing exonucleolytic (RNB) and endonucleolytic (PIN) active domains. Mutations in hDIS3 have been found in ∼10% of patients with multiple myeloma (MM). Here, we show that these mutations interfere with hDIS3 exonucleolytic activity. Yeast harboring corresponding mutations in DIS3 show growth inhibition and changes in nuclear RNA metabolism typical for exosome dysfunction. Construction of a conditional DIS3 knockout in the chicken DT40 cell line revealed that DIS3 is essential for cell survival, indicating that its function cannot be replaced by other exosome-associated nucleases: hDIS3L and hRRP6. Moreover, HEK293-derived cells, in which depletion of endogenous wild-type hDIS3 was complemented with exogenously expressed MM hDIS3 mutants, proliferate at a slower rate and exhibit aberrant RNA metabolism. Importantly, MM mutations are synthetically lethal with the hDIS3 PIN domain catalytic mutation both in yeast and human cells. Since mutations in PIN domain alone have little effect on cell physiology, our results predict the hDIS3 PIN domain as a potential drug target for MM patients with hDIS3 mutations. It is an interesting example of intramolecular synthetic lethality with putative therapeutic potential in humans.
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Affiliation(s)
- Rafal Tomecki
- Department of Biophysics, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawinskiego 5a, 02-106 Warsaw, Poland, Institute of Genetics and Biotechnology, Faculty of Biology, University of Warsaw, Pawinskiego 5a, 02-106 Warsaw, Poland and International Institute of Molecular and Cell Biology, Trojdena 4, 02-109 Warsaw, Poland
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39
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Stuparevic I, Mosrin-Huaman C, Hervouet-Coste N, Remenaric M, Rahmouni AR. Cotranscriptional recruitment of RNA exosome cofactors Rrp47p and Mpp6p and two distinct Trf-Air-Mtr4 polyadenylation (TRAMP) complexes assists the exonuclease Rrp6p in the targeting and degradation of an aberrant messenger ribonucleoprotein particle (mRNP) in yeast. J Biol Chem 2013; 288:31816-29. [PMID: 24047896 DOI: 10.1074/jbc.m113.491290] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
The cotranscriptional mRNA processing and packaging reactions that lead to the formation of export-competent messenger ribonucleoprotein particles (mRNPs) are under the surveillance of quality control steps. Aberrant mRNPs resulting from faulty events are retained in the nucleus with ensuing elimination of their mRNA component. The molecular mechanisms by which the surveillance system recognizes defective mRNPs and stimulates their destruction by the RNA degradation machinery are still not completely elucidated. Using an experimental approach in which mRNP formation in yeast is disturbed by the action of the bacterial Rho helicase, we have shown previously that the targeting of Rho-induced aberrant mRNPs is mediated by Rrp6p, which is recruited cotranscriptionally in association with Nrd1p following Rho action. Here we investigated the specific involvement in this quality control process of different cofactors associated with the nuclear RNA degradation machinery. We show that, in addition to the main hydrolytic action of the exonuclease Rrp6p, the cofactors Rrp47p, Mpp6p as well as the Trf-Air-Mtr4 polyadenylation (TRAMP) components Trf4p, Trf5p, and Air2p contribute significantly by stimulating the degradation process upon their cotranscriptional recruitment. Trf4p and Trf5p are apparently recruited in two distinct TRAMP complexes that both contain Air2p as component. Surprisingly, Rrp47p appears to play an important role in mutual protein stabilization with Rrp6p, which highlights a close association between the two partners. Together, our results provide an integrated view of how different cofactors of the RNA degradation machinery cooperate to target and eliminate aberrant mRNPs.
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Affiliation(s)
- Igor Stuparevic
- From the Centre de Biophysique Moléculaire, Unité Propre de Recherche (UPR) 4301 du CNRS, rue Charles Sadron, 45071 Orléans, France
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40
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Wichtowska D, Turowski TW, Boguta M. An interplay between transcription, processing, and degradation determines tRNA levels in yeast. WILEY INTERDISCIPLINARY REVIEWS-RNA 2013; 4:709-22. [PMID: 24039171 DOI: 10.1002/wrna.1190] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2013] [Revised: 07/09/2013] [Accepted: 07/10/2013] [Indexed: 11/06/2022]
Abstract
tRNA biogenesis in yeast involves the synthesis of the initial transcript by RNA polymerase III followed by processing and controlled degradation in both the nucleus and the cytoplasm. A vast landscape of regulatory elements controlling tRNA stability in yeast has emerged from recent studies. Diverse pathways of tRNA maturation generate multiple stable and unstable intermediates. A significant impact on tRNA stability is exerted by a variety of nucleotide modifications. Pre-tRNAs are targets of exosome-dependent surveillance in the nucleus. Some tRNAs that are hypomodified or bear specific destabilizing mutations are directed to the rapid tRNA decay pathway leading to 5'→3' exonucleolytic degradation by Rat1 and Xrn1. tRNA molecules are selectively marked for degradation by a double CCA at their 3' ends. In addition, under different stress conditions, tRNA half-molecules can be generated by independent endonucleolytic cleavage events. Recent studies reveal unexpected relationships between the subsequent steps of tRNA biosynthesis and the mechanisms controlling its quality and turnover.
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Affiliation(s)
- Dominika Wichtowska
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland
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41
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Schneider C, Tollervey D. Threading the barrel of the RNA exosome. Trends Biochem Sci 2013; 38:485-93. [PMID: 23910895 PMCID: PMC3838930 DOI: 10.1016/j.tibs.2013.06.013] [Citation(s) in RCA: 103] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2013] [Revised: 06/20/2013] [Accepted: 06/26/2013] [Indexed: 12/22/2022]
Abstract
A wide range of in vivo targets for the exosome complex has been established. RNA polymerase III transcripts have emerged as major substrates. The human nucleus has spatially localized forms of the exosome, with matching cofactors. Structural analyses reveal a highly conserved RNA path through the eukaryotic exosome.
In eukaryotes, the exosome complex degrades RNA backbones and plays key roles in RNA processing and surveillance. It was predicted that RNA substrates are threaded through a central channel. This pathway is conserved between eukaryotic and archaeal complexes, even though nuclease activity was lost from the nine-subunit eukaryotic core (EXO-9) and transferred to associated proteins. The exosome cooperates with nuclear and cytoplasmic cofactors, including RNA helicases Mtr4 and Ski2, respectively. Structures of an RNA-bound exosome and both helicases revealed how substrates are channeled through EXO-9 to the associated nuclease Rrp44. Recent high-throughput analyses provided fresh insights relating exosome structure to its diverse in vivo functions. They also revealed surprisingly high degradation rates for newly synthesized RNAs, particularly RNA polymerase III transcripts.
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Affiliation(s)
- Claudia Schneider
- Institute for Cell and Molecular Biosciences (ICaMB), Newcastle University, Newcastle upon Tyne, UK.
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Emerging roles for ribonucleoprotein modification and remodeling in controlling RNA fate. Trends Cell Biol 2013; 23:504-10. [PMID: 23756094 DOI: 10.1016/j.tcb.2013.05.001] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2013] [Revised: 05/01/2013] [Accepted: 05/02/2013] [Indexed: 12/26/2022]
Abstract
In the cell, mRNAs and non-coding RNAs exist in association with proteins to form ribonucleoprotein (RNP) complexes. Regulation of RNP stability and function is achieved by alterations to the RNP through poorly understood mechanisms into which recent studies have now begun to provide insight. This emerging body of work points to chemical modification of RNPs at the RNA or protein level and ATP-dependent RNP remodeling by RNA helicases/RNA-dependent ATPases as central events that dictate RNA fate. Some RNP modifications serve as tags for recruitment of regulatory proteins, with RNP modifiers and recruited proteins analogous to the writers and readers of chromatin modification, respectively. This review highlights examples in which RNP modification and ATP-dependent remodeling play key roles in the control of eukaryotic RNA fate, suggesting that we are only at the beginning of uncovering the multitude of ways in which RNP modification and remodeling impact RNA regulation.
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43
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Putnam AA, Jankowsky E. AMP sensing by DEAD-box RNA helicases. J Mol Biol 2013; 425:3839-45. [PMID: 23702290 DOI: 10.1016/j.jmb.2013.05.006] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2013] [Revised: 05/10/2013] [Accepted: 05/14/2013] [Indexed: 11/18/2022]
Abstract
In eukaryotes, cellular levels of adenosine monophosphate (AMP) signal the metabolic state of the cell. AMP concentrations increase significantly upon metabolic stress, such as glucose deprivation in yeast. Here, we show that several DEAD-box RNA helicases are sensitive to AMP, which is not produced during ATP hydrolysis by these enzymes. We find that AMP potently inhibits RNA binding and unwinding by the yeast DEAD-box helicases Ded1p, Mss116p, and eIF4A. However, the yeast DEAD-box helicases Sub2p and Dbp5p are not inhibited by AMP. Our observations identify a subset of DEAD-box helicases as enzymes with the capacity to directly link changes in AMP concentrations to RNA metabolism.
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Affiliation(s)
- Andrea A Putnam
- Center for RNA Molecular Biology and Department of Biochemistry, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
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44
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Porrua O, Libri D. RNA quality control in the nucleus: the Angels' share of RNA. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2013; 1829:604-11. [PMID: 23474120 DOI: 10.1016/j.bbagrm.2013.02.012] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2012] [Revised: 02/25/2013] [Accepted: 02/26/2013] [Indexed: 01/03/2023]
Abstract
Biological processes are not exempt from errors and RNA production is not an exception to this rule. Errors can arise stochastically or be genetically fixed and systematically appear in the biochemical or cellular phenotype. In any case, quality control mechanisms are essential to minimize the potentially toxic effects of faulty RNA production or processing. Although many RNA molecules express their functional potential in the cytoplasm, as messengers, adaptors or operators of gene expression pathways, a large share of quality control occurs in the nucleus. This is likely because the early timing of occurrence and the subcellular partition make the control more efficient, at least as long as the defects can be detected ahead of the cytoplasmic phase of the RNA life cycle. One crucial point in discussing RNA quality control resides in its definition. A stringent take would imply the existence of specific mechanisms to recognize the error and the consequent repair or elimination of the faulty molecule. One example in the RNA field could be the recognition of a premature stop codon by the nonsense-mediated decay pathway, discussed elsewhere in this issue. A more relaxed view posits that the thermodynamic or kinetic aftermath of a mistake (e.g. a blockage or a delay in processing) by itself constitutes the recognition event, which triggers downstream quality control. Because whether inappropriate molecules are specifically recognized remains unclear in many cases, we will adopt the more relaxed definition of RNA quality control. RNA repair remains episodic and the degradative elimination of crippled molecules appears to be the rule. Therefore we will briefly describe the actors of RNA degradation in the nucleus. Detailed analyses of the mechanism of action of these enzymes can be found in several excellent and recent reviews, including in this issue. Finally, we will restrict our analysis to the yeast model, which is used in the majority of RNA quality control studies, but examples exist in the literature indicating that many of the principles of RNA quality control described in yeast also apply to other eukaryotes. This article is part of a Special Issue entitled: RNA Decay mechanisms.
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Affiliation(s)
- Odil Porrua
- Centre de Génétique Moléculaire, CNRS, 91190 Gif sur Yvette, France
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Schmidt K, Butler JS. Nuclear RNA surveillance: role of TRAMP in controlling exosome specificity. WILEY INTERDISCIPLINARY REVIEWS-RNA 2013; 4:217-31. [PMID: 23417976 DOI: 10.1002/wrna.1155] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The advent of high-throughput sequencing technologies has revealed that pervasive transcription generates RNAs from nearly all regions of eukaryotic genomes. Normally, these transcripts undergo rapid degradation by a nuclear RNA surveillance system primarily featuring the RNA exosome. This multimeric protein complex plays a critical role in the efficient turnover and processing of a vast array of RNAs in the nucleus. Despite its initial discovery over a decade ago, important questions remain concerning the mechanisms that recruit and activate the nuclear exosome. Specificity and modulation of exosome activity requires additional protein cofactors, including the conserved TRAMP polyadenylation complex. Recent studies suggest that helicase and RNA-binding subunits of TRAMP direct RNA substrates for polyadenylation, which enhances their degradation by Dis3/Rrp44 and Rrp6, the two exosome-associated ribonucleases. These findings indicate that the exosome and TRAMP have evolved highly flexible functions that allow recognition of a wide range of RNA substrates. This flexibility provides the nuclear RNA surveillance system with the ability to regulate the levels of a broad range of coding and noncoding RNAs, which results in profound effects on gene expression, cellular development, gene silencing, and heterochromatin formation. This review summarizes recent findings on the nuclear RNA surveillance complexes, and speculates upon possible mechanisms for TRAMP-mediated substrate recognition and exosome activation.
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Affiliation(s)
- Karyn Schmidt
- Department of Biochemistry and Biophysics, Center for RNA Biology, University of Rochester Medical Center, Rochester, NY, USA
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Drążkowska K, Tomecki R, Stoduś K, Kowalska K, Czarnocki-Cieciura M, Dziembowski A. The RNA exosome complex central channel controls both exonuclease and endonuclease Dis3 activities in vivo and in vitro. Nucleic Acids Res 2013; 41:3845-58. [PMID: 23404585 PMCID: PMC3616716 DOI: 10.1093/nar/gkt060] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The RNA exosome is an essential ribonuclease complex involved in RNA processing and decay. It consists of a 9-subunit catalytically inert ring composed of six RNase PH-like proteins forming a central channel and three cap subunits with KH/S1 domains located at the top. The yeast exosome catalytic activity is supplied by the Dis3 (also known as Rrp44) protein, which has both endo- and exoribonucleolytic activities and the nucleus-specific exonuclease Rrp6. In vitro studies suggest that substrates reach the Dis3 exonucleolytic active site following passage through the ring channel, but in vivo support is lacking. Here, we constructed an Rrp41 ring subunit mutant with a partially blocked channel that led to thermosensitivity and synthetic lethality with Rrp6 deletion. Rrp41 mutation caused accumulation of nuclear and cytoplasmic exosome substrates including the non-stop decay reporter, for which degradation is dependent on either endonucleolytic or exonucleolytic Dis3 activities. This suggests that the central channel also controls endonucleolytic activity. In vitro experiments performed using Chaetomium thermophilum exosomes reconstituted from recombinant subunits confirmed this notion. Finally, we analysed the impact of a lethal mutation of conserved basic residues in Rrp4 cap subunit and found that it inhibits digestion of single-stranded and structured RNA substrates.
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Affiliation(s)
- Karolina Drążkowska
- Department of Biophysics, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, 02-106 Warsaw, Poland and Faculty of Biology, Institute of Genetics and Biotechnology, University of Warsaw, Pawińskiego 5a, 02-106 Warsaw, Poland
| | - Rafał Tomecki
- Department of Biophysics, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, 02-106 Warsaw, Poland and Faculty of Biology, Institute of Genetics and Biotechnology, University of Warsaw, Pawińskiego 5a, 02-106 Warsaw, Poland
| | - Krystian Stoduś
- Department of Biophysics, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, 02-106 Warsaw, Poland and Faculty of Biology, Institute of Genetics and Biotechnology, University of Warsaw, Pawińskiego 5a, 02-106 Warsaw, Poland
| | - Katarzyna Kowalska
- Department of Biophysics, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, 02-106 Warsaw, Poland and Faculty of Biology, Institute of Genetics and Biotechnology, University of Warsaw, Pawińskiego 5a, 02-106 Warsaw, Poland
| | - Mariusz Czarnocki-Cieciura
- Department of Biophysics, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, 02-106 Warsaw, Poland and Faculty of Biology, Institute of Genetics and Biotechnology, University of Warsaw, Pawińskiego 5a, 02-106 Warsaw, Poland
| | - Andrzej Dziembowski
- Department of Biophysics, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, 02-106 Warsaw, Poland and Faculty of Biology, Institute of Genetics and Biotechnology, University of Warsaw, Pawińskiego 5a, 02-106 Warsaw, Poland
- *To whom correspondence should be addressed. Tel: +48 225922033; Fax: +48 226584176;
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47
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Klauer AA, van Hoof A. Genetic interactions suggest multiple distinct roles of the arch and core helicase domains of Mtr4 in Rrp6 and exosome function. Nucleic Acids Res 2012; 41:533-41. [PMID: 23143101 PMCID: PMC3592479 DOI: 10.1093/nar/gks1013] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
The RNA exosome is responsible for a wide variety of RNA processing and degradation reactions. The activity and specificity of the RNA exosome is thought to be controlled by a number of cofactors. Mtr4 is an essential RNA-dependent adenosine triphosphatase that is required for all of the nuclear functions of the RNA exosome. The crystal structure of Mtr4 uncovered a domain that is conserved in the RNA exosome cofactors Mtr4 and Ski2 but not in other helicases, suggesting it has an important role related to exosome activation. Rrp6 provides the nuclear exosome with one of its three nuclease activities, and previous findings suggested that the arch domain is specifically required for Rrp6 functions. Here, we report that the genetic interactions between the arch domain of Mtr4 and Rrp6 cannot be explained by the arch domain solely acting in Rrp6-dependent processing reactions. Specifically, we show that the arch domain is not required for all Rrp6 functions, and that the arch domain also functions independently of Rrp6. Finally, we show that the arch domain of Ski2, the cytoplasmic counterpart of Mtr4, is required for Ski2’s function, thereby confirming that the arch domains of these cofactors function independently of Rrp6.
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Affiliation(s)
- A Alejandra Klauer
- Department of Microbiology and Molecular Genetics, University of Texas Health Science Center-Houston and The University of Texas Graduate School of Biomedical Sciences, 6431 Fannin Street, MSB 1.212, Houston, TX 77030, USA
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48
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Dewe JM, Whipple JM, Chernyakov I, Jaramillo LN, Phizicky EM. The yeast rapid tRNA decay pathway competes with elongation factor 1A for substrate tRNAs and acts on tRNAs lacking one or more of several modifications. RNA (NEW YORK, N.Y.) 2012; 18:1886-96. [PMID: 22895820 PMCID: PMC3446711 DOI: 10.1261/rna.033654.112] [Citation(s) in RCA: 95] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
The structural and functional integrity of tRNA is crucial for translation. In the yeast Saccharomyces cerevisiae, certain aberrant pre-tRNA species are subject to nuclear surveillance, leading to 3' exonucleolytic degradation, and certain mature tRNA species are subject to rapid tRNA decay (RTD) if they are appropriately hypomodified or bear specific destabilizing mutations, leading to 5'-3' exonucleolytic degradation by Rat1 and Xrn1. Thus, trm8-Δ trm4-Δ strains are temperature sensitive due to lack of m(7)G(46) and m(5)C and the consequent RTD of tRNA(Val(AAC)), and tan1-Δ trm44-Δ strains are temperature sensitive due to lack of ac(4)C(12) and Um(44) and the consequent RTD of tRNA(Ser(CGA)) and tRNA(Ser(UGA)). It is unknown how the RTD pathway interacts with translation and other cellular processes, and how generally this pathway acts on hypomodified tRNAs. We provide evidence here that elongation factor 1A (EF-1A) competes with the RTD pathway for substrate tRNAs, since its overexpression suppresses the tRNA degradation and the growth defect of strains subject to RTD, whereas reduced levels of EF-1A have the opposite effect. We also provide evidence that RTD acts on a variety of tRNAs lacking one or more different modifications, since trm1-Δ trm4-Δ mutants are subject to RTD of tRNA(Ser(CGA)) and tRNA(Ser(UGA)) due to lack of m(2,2)G(26) and m(5)C, and since trm8-Δ, tan1-Δ, and trm1-Δ single mutants are each subject to RTD. These results demonstrate that RTD interacts with the translation machinery and acts widely on hypomodified tRNAs.
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Affiliation(s)
- Joshua M. Dewe
- Department of Biochemistry and Biophysics, Center for RNA Biology, University of Rochester School of Medicine, Rochester, New York 14642, USA
| | - Joseph M. Whipple
- Department of Biochemistry and Biophysics, Center for RNA Biology, University of Rochester School of Medicine, Rochester, New York 14642, USA
| | - Irina Chernyakov
- Department of Biochemistry and Biophysics, Center for RNA Biology, University of Rochester School of Medicine, Rochester, New York 14642, USA
| | - Laura N. Jaramillo
- Department of Biochemistry and Biophysics, Center for RNA Biology, University of Rochester School of Medicine, Rochester, New York 14642, USA
| | - Eric M. Phizicky
- Department of Biochemistry and Biophysics, Center for RNA Biology, University of Rochester School of Medicine, Rochester, New York 14642, USA
- Corresponding authorE-mail
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49
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Abstract
Superfamily 2 helicases are involved in all aspects of RNA metabolism, and many steps in DNA metabolism. This review focuses on the basic mechanistic, structural and biological properties of each of the families of helicases within superfamily 2. There are ten separate families of helicases within superfamily 2, each playing specific roles in nucleic acid metabolism. The mechanisms of action are diverse, as well as the effect on the nucleic acid. Some families translocate on single-stranded nucleic acid and unwind duplexes, some unwind double-stranded nucleic acids without translocation, and some translocate on double-stranded or single-stranded nucleic acids without unwinding.
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Affiliation(s)
- Alicia K Byrd
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205, USA
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50
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RNA unwinding by the Trf4/Air2/Mtr4 polyadenylation (TRAMP) complex. Proc Natl Acad Sci U S A 2012; 109:7292-7. [PMID: 22532666 DOI: 10.1073/pnas.1201085109] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Many RNA-processing events in the cell nucleus involve the Trf4/Air2/Mtr4 polyadenylation (TRAMP) complex, which contains the poly(A) polymerase Trf4p, the Zn-knuckle protein Air2p, and the RNA helicase Mtr4p. TRAMP polyadenylates RNAs designated for processing by the nuclear exosome. In addition, TRAMP functions as an exosome cofactor during RNA degradation, and it has been speculated that this role involves disruption of RNA secondary structure. However, it is unknown whether TRAMP displays RNA unwinding activity. It is also not clear how unwinding would be coordinated with polyadenylation and the function of the RNA helicase Mtr4p in modulating poly(A) addition. Here, we show that TRAMP robustly unwinds RNA duplexes. The unwinding activity of Mtr4p is significantly stimulated by Trf4p/Air2p, but the stimulation of Mtr4p does not depend on ongoing polyadenylation. Nonetheless, polyadenylation enables TRAMP to unwind RNA substrates that it otherwise cannot separate. Moreover, TRAMP displays optimal unwinding activity on substrates with a minimal Mtr4p binding site comprised of adenylates. Our results suggest a model for coordination between unwinding and polyadenylation activities by TRAMP that reveals remarkable synergy between helicase and poly(A) polymerase.
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