1
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Li H, Ding Z, Fang ZY, Long N, Ang HY, Zhang Y, Fan YJ, Xu YZ. Conserved intronic secondary structures with concealed branch sites regulate alternative splicing of poison exons. Nucleic Acids Res 2024:gkae185. [PMID: 38499485 DOI: 10.1093/nar/gkae185] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2023] [Revised: 02/23/2024] [Accepted: 03/05/2024] [Indexed: 03/20/2024] Open
Abstract
Alternative splicing (AS) generates multiple RNA isoforms and increases the complexities of transcriptomes and proteomes. However, it remains unclear how RNA structures contribute to AS regulation. Here, we systematically search transcriptomes for secondary structures with concealed branch sites (BSs) in the alternatively spliced introns and predict thousands of them from six organisms, of which many are evolutionarily conserved. Intriguingly, a highly conserved stem-loop structure with concealed BSs is found in animal SF3B3 genes and colocalizes with a downstream poison exon (PE). Destabilization of this structure allows increased usage of the BSs and results in enhanced PE inclusion in human and Drosophila cells, leading to decreased expression of SF3B3. This structure is experimentally validated using an in-cell SHAPE-MaP assay. Through RNA interference screens of 28 RNA-binding proteins, we find that this stem-loop structure is sensitive to U2 factors. Furthermore, we find that SF3B3 also facilitates DNA repair and protects genome stability by enhancing interaction between ERCC6/CSB and arrested RNA polymerase II. Importantly, both Drosophila and human cells with the secondary structure mutated by genome editing exhibit altered DNA repair in vivo. This study provides a novel and common mechanism for AS regulation of PEs and reveals a physiological function of SF3B3 in DNA repair.
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Affiliation(s)
- Hao Li
- RNA Institute, State Key Laboratory of Virology, Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, TaiKang Center for Life and Medical Sciences, Wuhan University, Hubei 430072, China
| | - Zhan Ding
- RNA Institute, State Key Laboratory of Virology, Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, TaiKang Center for Life and Medical Sciences, Wuhan University, Hubei 430072, China
| | - Zhuo-Ya Fang
- RNA Institute, State Key Laboratory of Virology, Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, TaiKang Center for Life and Medical Sciences, Wuhan University, Hubei 430072, China
| | - Ni Long
- RNA Institute, State Key Laboratory of Virology, Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, TaiKang Center for Life and Medical Sciences, Wuhan University, Hubei 430072, China
| | - Hao-Yang Ang
- RNA Institute, State Key Laboratory of Virology, Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, TaiKang Center for Life and Medical Sciences, Wuhan University, Hubei 430072, China
| | - Yu Zhang
- Genome Institute of Singapore, Agency for Science, Technology and Research (A*STAR), Singapore, 138672, Singapore
| | - Yu-Jie Fan
- RNA Institute, State Key Laboratory of Virology, Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, TaiKang Center for Life and Medical Sciences, Wuhan University, Hubei 430072, China
| | - Yong-Zhen Xu
- RNA Institute, State Key Laboratory of Virology, Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, TaiKang Center for Life and Medical Sciences, Wuhan University, Hubei 430072, China
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2
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Sheng M, Zhang Y, Wang Y, Liu W, Wang X, Ke T, Liu P, Wang S, Shao W. Decoding the role of aberrant RNA alternative splicing in hepatocellular carcinoma: a comprehensive review. J Cancer Res Clin Oncol 2023; 149:17691-17708. [PMID: 37898981 DOI: 10.1007/s00432-023-05474-8] [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: 07/18/2023] [Accepted: 10/10/2023] [Indexed: 10/31/2023]
Abstract
During eukaryotic gene expression, alternative splicing of messenger RNA precursors is critical in increasing protein diversity and regulatory complexity. Multiple transcript isoforms could be produced by alternative splicing from a single gene; they could eventually be translated into protein isoforms with deleted, added, or altered domains or produce transcripts containing premature termination codons that could be targeted by nonsense-mediated mRNA decay. Alternative splicing can generate proteins with similar, different, or even opposite functions. Increasingly strong evidence indicates that abnormal RNA splicing is a prevalent and crucial occurrence in cellular differentiation, tissue advancement, and the development and progression of cancer. Aberrant alternative splicing could affect cancer cell activities such as growth, apoptosis, invasiveness, drug resistance, angiogenesis, and metabolism. This systematic review provides a comprehensive overview of the impact of abnormal RNA alternative splicing on the development and progression of hepatocellular carcinoma.
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Affiliation(s)
- Mengfei Sheng
- School of Basic Medical Sciences, Anhui Medical University, Hefei, China
| | - Yuanyuan Zhang
- School of Basic Medical Sciences, Anhui Medical University, Hefei, China
| | - Yaoyun Wang
- School of Basic Medical Sciences, Anhui Medical University, Hefei, China
| | - Weiyi Liu
- School of Basic Medical Sciences, Anhui Medical University, Hefei, China
| | - Xingyu Wang
- School of Basic Medical Sciences, Anhui Medical University, Hefei, China
| | - Tiaoying Ke
- School of Basic Medical Sciences, Anhui Medical University, Hefei, China
| | - Pingyang Liu
- Department of Epidemiology and Biostatistics, University of California, San Francisco, San Francisco, CA, USA
| | - Sihan Wang
- Department of Clinical Medicine, Bengbu Medical College, Bengbu, China
| | - Wei Shao
- School of Basic Medical Sciences, Anhui Medical University, Hefei, China.
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3
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Hou S, Li G, Xu B, Dong H, Zhang S, Fu Y, Shi J, Li L, Fu J, Shi F, Meng Y, Jin Y. Trans-splicing facilitated by RNA pairing greatly expands sDscam isoform diversity but not homophilic binding specificity. SCIENCE ADVANCES 2022; 8:eabn9458. [PMID: 35857463 PMCID: PMC9258826 DOI: 10.1126/sciadv.abn9458] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/03/2022] [Accepted: 05/21/2022] [Indexed: 06/15/2023]
Abstract
The Down syndrome cell adhesion molecule 1 (Dscam1) gene can generate tens of thousands of isoforms via alternative splicing, which is essential for nervous and immune functions. Chelicerates generate approximately 50 to 100 shortened Dscam (sDscam) isoforms by alternative promoters, similar to mammalian protocadherins. Here, we reveal that trans-splicing markedly increases the repository of sDscamβ isoforms in Tetranychus urticae. Unexpectedly, every variable exon cassette engages in trans-splicing with constant exons from another cluster. Moreover, we provide evidence that competing RNA pairing not only governs alternative cis-splicing but also facilitates trans-splicing. Trans-spliced sDscam isoforms mediate cell adhesion ability but exhibit the same homophilic binding specificity as their cis-spliced counterparts. Thus, we reveal a single sDscam locus that generates diverse adhesion molecules through cis- and trans-splicing coupled with alternative promoters. These findings expand understanding of the mechanism underlying molecular diversity and have implications for the molecular control of neuronal and/or immune specificity.
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Affiliation(s)
- Shouqing Hou
- MOE Laboratory of Biosystems Homeostasis and Protection and Innovation Center for Cell Signaling Network, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang ZJ310058, P. R. China
| | - Guo Li
- MOE Laboratory of Biosystems Homeostasis and Protection and Innovation Center for Cell Signaling Network, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang ZJ310058, P. R. China
| | - Bingbing Xu
- MOE Laboratory of Biosystems Homeostasis and Protection and Innovation Center for Cell Signaling Network, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang ZJ310058, P. R. China
| | - Haiyang Dong
- MOE Laboratory of Biosystems Homeostasis and Protection and Innovation Center for Cell Signaling Network, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang ZJ310058, P. R. China
| | - Shixin Zhang
- MOE Laboratory of Biosystems Homeostasis and Protection and Innovation Center for Cell Signaling Network, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang ZJ310058, P. R. China
| | - Ying Fu
- MOE Laboratory of Biosystems Homeostasis and Protection and Innovation Center for Cell Signaling Network, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang ZJ310058, P. R. China
| | - Jilong Shi
- MOE Laboratory of Biosystems Homeostasis and Protection and Innovation Center for Cell Signaling Network, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang ZJ310058, P. R. China
| | - Lei Li
- MOE Laboratory of Biosystems Homeostasis and Protection and Innovation Center for Cell Signaling Network, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang ZJ310058, P. R. China
| | - Jiayan Fu
- MOE Laboratory of Biosystems Homeostasis and Protection and Innovation Center for Cell Signaling Network, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang ZJ310058, P. R. China
| | - Feng Shi
- MOE Laboratory of Biosystems Homeostasis and Protection and Innovation Center for Cell Signaling Network, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang ZJ310058, P. R. China
| | - Yijun Meng
- College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, Zhejiang ZJ310018, P. R. China
| | - Yongfeng Jin
- MOE Laboratory of Biosystems Homeostasis and Protection and Innovation Center for Cell Signaling Network, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang ZJ310058, P. R. China
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4
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Maul-Newby HM, Amorello AN, Sharma T, Kim JH, Modena MS, Prichard BE, Jurica MS. A model for DHX15 mediated disassembly of A-complex spliceosomes. RNA (NEW YORK, N.Y.) 2022; 28:583-595. [PMID: 35046126 PMCID: PMC8925973 DOI: 10.1261/rna.078977.121] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Accepted: 01/03/2022] [Indexed: 06/14/2023]
Abstract
A critical step of pre-mRNA splicing is the recruitment of U2 snRNP to the branch point sequence of an intron. U2 snRNP conformation changes extensively during branch helix formation, and several RNA-dependent ATPases are implicated in the process. However, the molecular mechanisms involved remain to be fully dissected. We took advantage of the differential nucleotide triphosphates requirements for DExD/H-box enzymes to probe their contributions to in vitro spliceosome assembly. Both ATP and GTP hydrolysis support the formation of A-complex, indicating the activity of a DEAH-enzyme because DEAD-enzymes are selective for ATP. We immunodepleted DHX15 to assess its involvement, and although splicing efficiency decreases with reduced DHX15, A-complex accumulation incongruently increases. DHX15 depletion also results in the persistence of the atypical ATP-independent interaction between U2 snRNP and a minimal substrate that is otherwise destabilized in the presence of either ATP or GTP. These results lead us to hypothesize that DHX15 plays a quality control function in U2 snRNP's engagement with an intron. In efforts to identify the RNA target of DHX15, we determined that an extended polypyrimidine tract is not necessary for disruption of the atypical interaction between U2 snRNP and the minimal substrate. We also examined U2 snRNA by RNase H digestion and identified nucleotides in the branch binding region that become accessible with both ATP and GTP hydrolysis, again implicating a DEAH-enzyme. Together, our results demonstrate that multiple ATP-dependent rearrangements are likely involved in U2 snRNP addition to the spliceosome and that DHX15 may have an expanded role in maintaining splicing fidelity.
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Affiliation(s)
- Hannah M Maul-Newby
- Department of Molecular Cell and Developmental Biology, University of California Santa Cruz, Santa Cruz, California 95064, USA
- Center for Molecular Biology of RNA, University of California Santa Cruz, Santa Cruz, California 95064, USA
| | - Angela N Amorello
- Department of Molecular Cell and Developmental Biology, University of California Santa Cruz, Santa Cruz, California 95064, USA
- Center for Molecular Biology of RNA, University of California Santa Cruz, Santa Cruz, California 95064, USA
| | - Turvi Sharma
- Department of Molecular Cell and Developmental Biology, University of California Santa Cruz, Santa Cruz, California 95064, USA
- Center for Molecular Biology of RNA, University of California Santa Cruz, Santa Cruz, California 95064, USA
| | - John H Kim
- Department of Molecular Cell and Developmental Biology, University of California Santa Cruz, Santa Cruz, California 95064, USA
- Center for Molecular Biology of RNA, University of California Santa Cruz, Santa Cruz, California 95064, USA
| | - Matthew S Modena
- Department of Molecular Cell and Developmental Biology, University of California Santa Cruz, Santa Cruz, California 95064, USA
- Center for Molecular Biology of RNA, University of California Santa Cruz, Santa Cruz, California 95064, USA
| | - Beth E Prichard
- Department of Molecular Cell and Developmental Biology, University of California Santa Cruz, Santa Cruz, California 95064, USA
- Center for Molecular Biology of RNA, University of California Santa Cruz, Santa Cruz, California 95064, USA
| | - Melissa S Jurica
- Department of Molecular Cell and Developmental Biology, University of California Santa Cruz, Santa Cruz, California 95064, USA
- Center for Molecular Biology of RNA, University of California Santa Cruz, Santa Cruz, California 95064, USA
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5
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SF3B4 promotes ovarian cancer progression by regulating alternative splicing of RAD52. Cell Death Dis 2022; 13:179. [PMID: 35210412 PMCID: PMC8873359 DOI: 10.1038/s41419-022-04630-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Revised: 01/28/2022] [Accepted: 02/04/2022] [Indexed: 11/08/2022]
Abstract
Many studies have proven that splicing factors are crucial for human malignant tumor development. However, as a classical splicing factor, the expression of SF3B4 is not clear, and its biological function needs to be further clarified in ovarian cancer (OC). We determined that SF3B4 was obviously upregulated and its high expression was associated with poor prognosis in OC patients. In vitro and in vivo assays suggested that SF3B4 overexpression promoted OC cell proliferation and mobility, and downregulation of SF3B4 had the opposite effect. Further studies found that miR-509–3p decreased SF3B4 mRNA expression by binding to the 3’ -UTR of SF3B4 directly. Importantly, we revealed that RAD52 was a potential target of SF3B4 through alternative splicing events analysis. Loss of SF3B4 led to decreased expression of RAD52, owing to intron 8 retention and generation of premature termination codons. Moreover, decreased expression of RAD52 partially counteracted the tumor-promoting effect of SF3B4 overexpression. In conclusion, our results suggested that SF3B4, negatively regulated by miR-509–3p, promoted OC progression through effective splicing of RAD52. Therefore, SF3B4 may be a promising biomarker and effective therapeutic target for OC.
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6
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A single m 6A modification in U6 snRNA diversifies exon sequence at the 5' splice site. Nat Commun 2021; 12:3244. [PMID: 34050143 PMCID: PMC8163875 DOI: 10.1038/s41467-021-23457-6] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Accepted: 04/29/2021] [Indexed: 11/09/2022] Open
Abstract
N6-methyladenosine (m6A) is a modification that plays pivotal roles in RNA metabolism and function, although its functions in spliceosomal U6 snRNA remain unknown. To elucidate its role, we conduct a large-scale transcriptome analysis of a Schizosaccharomyces pombe strain lacking this modification and found a global change of pre-mRNA splicing. The most significantly impacted introns are enriched for adenosine at the fourth position pairing the m6A in U6 snRNA, and exon sequences weakly recognized by U5 snRNA. This suggests cooperative recognition of 5' splice site by U6 and U5 snRNPs, and also a role of m6A facilitating efficient recognition of the splice sites weakly interacting with U5 snRNA, indicating that U6 snRNA m6A relaxes the 5' exon constraint and allows protein sequence diversity along with explosively increasing number of introns over the course of eukaryotic evolution.
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7
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Yeh FL, Chang SL, Ahmed GR, Liu HI, Tung L, Yeh CS, Lanier LS, Maeder C, Lin CM, Tsai SC, Hsiao WY, Chang WH, Chang TH. Activation of Prp28 ATPase by phosphorylated Npl3 at a critical step of spliceosome remodeling. Nat Commun 2021; 12:3082. [PMID: 34035302 PMCID: PMC8149812 DOI: 10.1038/s41467-021-23459-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2020] [Accepted: 04/29/2021] [Indexed: 11/10/2022] Open
Abstract
Splicing, a key step in the eukaryotic gene-expression pathway, converts precursor messenger RNA (pre-mRNA) into mRNA by excising introns and ligating exons. This task is accomplished by the spliceosome, a macromolecular machine that must undergo sequential conformational changes to establish its active site. Each of these major changes requires a dedicated DExD/H-box ATPase, but how these enzymes are activated remain obscure. Here we show that Prp28, a yeast DEAD-box ATPase, transiently interacts with the conserved 5' splice-site (5'SS) GU dinucleotide and makes splicing-dependent contacts with the U1 snRNP protein U1C, and U4/U6.U5 tri-snRNP proteins, Prp8, Brr2, and Snu114. We further show that Prp28's ATPase activity is potentiated by the phosphorylated Npl3, but not the unphosphorylated Npl3, thus suggesting a strategy for regulating DExD/H-box ATPases. We propose that Npl3 is a functional counterpart of the metazoan-specific Prp28 N-terminal region, which can be phosphorylated and serves as an anchor to human spliceosome.
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Affiliation(s)
- Fu-Lung Yeh
- Genomics Research Center, Academia Sinica, Taipei, Taiwan
| | | | | | - Hsin-I Liu
- Genomics Research Center, Academia Sinica, Taipei, Taiwan
| | - Luh Tung
- Genomics Research Center, Academia Sinica, Taipei, Taiwan
| | - Chung-Shu Yeh
- Genomics Research Center, Academia Sinica, Taipei, Taiwan
| | - Leah Stands Lanier
- Department of Biology, Washington and Lee University, Lexington, VA, USA
| | - Corina Maeder
- Department of Chemistry, Trinity University, San Antonio, TX, USA
| | - Che-Min Lin
- Genomics Research Center, Academia Sinica, Taipei, Taiwan
| | - Shu-Chun Tsai
- Genomics Research Center, Academia Sinica, Taipei, Taiwan
| | - Wan-Yi Hsiao
- Genomics Research Center, Academia Sinica, Taipei, Taiwan
- Institute of Biochemistry and Molecular Biology, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - Wei-Hau Chang
- Institute of Chemistry, Academia Sinica, Taipei, Taiwan
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8
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Wang S, Wang Z, Li J, Qin J, Song J, Li Y, Zhao L, Zhang X, Guo H, Shao C, Kong B, Liu Z. Splicing factor USP39 promotes ovarian cancer malignancy through maintaining efficient splicing of oncogenic HMGA2. Cell Death Dis 2021; 12:294. [PMID: 33731694 PMCID: PMC7969951 DOI: 10.1038/s41419-021-03581-3] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Revised: 03/01/2021] [Accepted: 03/03/2021] [Indexed: 12/16/2022]
Abstract
Aberrant expression of splicing factors was found to promote tumorigenesis and the development of human malignant tumors. Nevertheless, the underlying mechanisms and functional relevance remain elusive. We here show that USP39, a component of the spliceosome, is frequently overexpressed in high-grade serous ovarian carcinoma (HGSOC) and that an elevated level of USP39 is associated with a poor prognosis. USP39 promotes proliferation/invasion in vitro and tumor growth in vivo. Importantly, USP39 was transcriptionally activated by the oncogene protein c-MYC in ovarian cancer cells. We further demonstrated that USP39 colocalizes with spliceosome components in nuclear speckles. Transcriptomic analysis revealed that USP39 deletion led to globally impaired splicing that is characterized by skipped exons and overrepresentation of introns and intergenic regions. Furthermore, RNA immunoprecipitation sequencing showed that USP39 preferentially binds to exon-intron regions near 5' and 3' splicing sites. In particular, USP39 facilitates efficient splicing of HMGA2 and thereby increases the malignancy of ovarian cancer cells. Taken together, our results indicate that USP39 functions as an oncogenic splicing factor in ovarian cancer and represents a potential target for ovarian cancer therapy.
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Affiliation(s)
- Shourong Wang
- Department of Obstetrics and Gynecology, Qilu Hospital, Cheeloo College of Medicine, Shandong University, 107 Wenhua Xi Road, Jinan, 250012, Shandong Province, China.,Key Laboratory of Experimental Teratology, Ministry of Education, Department of Cell Biology, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, 250012, China
| | - Zixiang Wang
- Department of Obstetrics and Gynecology, Qilu Hospital, Cheeloo College of Medicine, Shandong University, 107 Wenhua Xi Road, Jinan, 250012, Shandong Province, China.,Key Laboratory of Experimental Teratology, Ministry of Education, Department of Cell Biology, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, 250012, China
| | - Jieyin Li
- Key Laboratory of Experimental Teratology, Ministry of Education, Department of Cell Biology, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, 250012, China
| | - Junchao Qin
- Key Laboratory of Experimental Teratology, Ministry of Education, Department of Cell Biology, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, 250012, China
| | - Jianping Song
- Key Laboratory of Experimental Teratology, Ministry of Education, Department of Cell Biology, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, 250012, China
| | - Yingwei Li
- Department of Obstetrics and Gynecology, Qilu Hospital, Cheeloo College of Medicine, Shandong University, 107 Wenhua Xi Road, Jinan, 250012, Shandong Province, China
| | - Ling Zhao
- Key Laboratory of Experimental Teratology, Ministry of Education, Department of Cell Biology, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, 250012, China
| | - Xiyu Zhang
- Molecular Medicine and Genetics, Cheeloo College of Medicine, Shandong University School of Medicine, 44 Wenhua Xi Road, Jinan, Shandong, 250012, China
| | - Haiyang Guo
- Department of Clinical Laboratory, The Second Hospital of Shandong University, Jinan, 250012, China
| | - Changshun Shao
- Institutes for Translational Medicine, State Key Laboratory of Radiation Medicine and Protection, Soochow University, Suzhou, 215123, Jiangsu Province, China
| | - Beihua Kong
- Department of Obstetrics and Gynecology, Qilu Hospital, Cheeloo College of Medicine, Shandong University, 107 Wenhua Xi Road, Jinan, 250012, Shandong Province, China.
| | - Zhaojian Liu
- Key Laboratory of Experimental Teratology, Ministry of Education, Department of Cell Biology, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, 250012, China.
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9
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Bud23 promotes the final disassembly of the small subunit Processome in Saccharomyces cerevisiae. PLoS Genet 2020; 16:e1009215. [PMID: 33306676 PMCID: PMC7758049 DOI: 10.1371/journal.pgen.1009215] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Revised: 12/23/2020] [Accepted: 10/21/2020] [Indexed: 01/18/2023] Open
Abstract
The first metastable assembly intermediate of the eukaryotic ribosomal small subunit (SSU) is the SSU Processome, a large complex of RNA and protein factors that is thought to represent an early checkpoint in the assembly pathway. Transition of the SSU Processome towards continued maturation requires the removal of the U3 snoRNA and biogenesis factors as well as ribosomal RNA processing. While the factors that drive these events are largely known, how they do so is not. The methyltransferase Bud23 has a role during this transition, but its function, beyond the nonessential methylation of ribosomal RNA, is not characterized. Here, we have carried out a comprehensive genetic screen to understand Bud23 function. We identified 67 unique extragenic bud23Δ-suppressing mutations that mapped to genes encoding the SSU Processome factors DHR1, IMP4, UTP2 (NOP14), BMS1 and the SSU protein RPS28A. These factors form a physical interaction network that links the binding site of Bud23 to the U3 snoRNA and many of the amino acid substitutions weaken protein-protein and protein-RNA interactions. Importantly, this network links Bud23 to the essential GTPase Bms1, which acts late in the disassembly pathway, and the RNA helicase Dhr1, which catalyzes U3 snoRNA removal. Moreover, particles isolated from cells lacking Bud23 accumulated late SSU Processome factors and ribosomal RNA processing defects. We propose a model in which Bud23 dissociates factors surrounding its binding site to promote SSU Processome progression. Ribosomes are the molecular machines that synthesize proteins and are composed of a large and a small subunit which carry out the essential functions of polypeptide synthesis and mRNA decoding, respectively. Ribosome production is tightly linked to cellular growth as cells must produce enough ribosomes to meet their protein needs. However, ribosome assembly is a metabolically expensive pathway that must be balanced with other cellular energy needs and regulated accordingly. In eukaryotes, the small subunit (SSU) Processome is a metastable intermediate that ultimately progresses towards a mature SSU through the release of biogenesis factors. The decision to progress the SSU Processome is thought to be an early checkpoint in the SSU assembly pathway, but insight into the mechanisms of progression is needed. Previous studies suggest that Bud23 plays an uncharacterized role during SSU Processome progression. Here, we used a genetic approach to understand its function and found that Bud23 is connected to a network of SSU Processome factors that stabilize the particle. Interestingly, two of these factors are enzymes that are needed for progression. We conclude that Bud23 promotes the release of factors surrounding its binding site to induce structural rearrangements during the progression of the SSU Processome.
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10
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Defective minor spliceosomes induce SMA-associated phenotypes through sensitive intron-containing neural genes in Drosophila. Nat Commun 2020; 11:5608. [PMID: 33154379 PMCID: PMC7644725 DOI: 10.1038/s41467-020-19451-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2019] [Accepted: 10/13/2020] [Indexed: 01/31/2023] Open
Abstract
The minor spliceosome is evolutionarily conserved in higher eukaryotes, but its biological significance remains poorly understood. Here, by precise CRISPR/Cas9-mediated disruption of the U12 and U6atac snRNAs, we report that a defective minor spliceosome is responsible for spinal muscular atrophy (SMA) associated phenotypes in Drosophila. Using a newly developed bioinformatic approach, we identified a large set of minor spliceosome-sensitive splicing events and demonstrate that three sensitive intron-containing neural genes, Pcyt2, Zmynd10, and Fas3, directly contribute to disease development as evidenced by the ability of their cDNAs to rescue the SMA-associated phenotypes in muscle development, neuromuscular junctions, and locomotion. Interestingly, many splice sites in sensitive introns are recognizable by both minor and major spliceosomes, suggesting a new mechanism of splicing regulation through competition between minor and major spliceosomes. These findings reveal a vital contribution of the minor spliceosome to SMA and to regulated splicing in animals.
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11
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Shao W, Ding Z, Zheng ZZ, Shen JJ, Shen YX, Pu J, Fan YJ, Query CC, Xu YZ. Prp5-Spt8/Spt3 interaction mediates a reciprocal coupling between splicing and transcription. Nucleic Acids Res 2020; 48:5799-5813. [PMID: 32399566 PMCID: PMC7293005 DOI: 10.1093/nar/gkaa311] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Revised: 04/08/2020] [Accepted: 05/03/2020] [Indexed: 01/23/2023] Open
Abstract
Transcription and pre-mRNA splicing are coupled to promote gene expression and regulation. However, mechanisms by which transcription and splicing influence each other are still under investigation. The ATPase Prp5p is required for pre-spliceosome assembly and splicing proofreading at the branch-point region. From an open UV mutagenesis screen for genetic suppressors of prp5 defects and subsequent targeted testing, we identify components of the TBP-binding module of the Spt–Ada–Gcn5 Acetyltransferase (SAGA) complex, Spt8p and Spt3p. Spt8Δ and spt3Δ rescue the cold-sensitivity of prp5-GAR allele, and prp5 mutants restore growth of spt8Δ and spt3Δ strains on 6-azauracil. By chromatin immunoprecipitation (ChIP), we find that prp5 alleles decrease recruitment of RNA polymerase II (Pol II) to an intron-containing gene, which is rescued by spt8Δ. Further ChIP-seq reveals that global effects on Pol II-binding are mutually rescued by prp5-GAR and spt8Δ. Inhibited splicing caused by prp5-GAR is also restored by spt8Δ. In vitro assays indicate that Prp5p directly interacts with Spt8p, but not Spt3p. We demonstrate that Prp5p's splicing proofreading is modulated by Spt8p and Spt3p. Therefore, this study reveals that interactions between the TBP-binding module of SAGA and the spliceosomal ATPase Prp5p mediate a balance between transcription initiation/elongation and pre-spliceosome assembly.
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Affiliation(s)
- Wei Shao
- School of Basic Medical Sciences, Anhui Medical University, Hefei, Anhui 230032, China.,State Key Laboratory of Virology, Hubei Key Laboratory of Cell Homeostasis, College of Life Science, Wuhan University, Wuhan, Hubei 430072, China
| | - Zhan Ding
- State Key Laboratory of Virology, Hubei Key Laboratory of Cell Homeostasis, College of Life Science, Wuhan University, Wuhan, Hubei 430072, China.,Key Laboratory of Insect Developmental and Evolutionary Biology, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China
| | - Zeng-Zhang Zheng
- Key Laboratory of Insect Developmental and Evolutionary Biology, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China
| | - Ji-Jia Shen
- School of Basic Medical Sciences, Anhui Medical University, Hefei, Anhui 230032, China
| | - Yu-Xian Shen
- School of Basic Medical Sciences, Anhui Medical University, Hefei, Anhui 230032, China
| | - Jia Pu
- Key Laboratory of Insect Developmental and Evolutionary Biology, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China
| | - Yu-Jie Fan
- State Key Laboratory of Virology, Hubei Key Laboratory of Cell Homeostasis, College of Life Science, Wuhan University, Wuhan, Hubei 430072, China
| | - Charles C Query
- Department of Cell Biology, Albert Einstein College of Medicine, NY 10461, USA
| | - Yong-Zhen Xu
- State Key Laboratory of Virology, Hubei Key Laboratory of Cell Homeostasis, College of Life Science, Wuhan University, Wuhan, Hubei 430072, China
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12
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Qiu C, Zhang Y, Fan YJ, Pang TL, Su Y, Zhan S, Xu YZ. HITS-CLIP reveals sex-differential RNA binding and alterative splicing regulation of SRm160 in Drosophila. J Mol Cell Biol 2020; 11:170-181. [PMID: 29750417 DOI: 10.1093/jmcb/mjy029] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2017] [Revised: 03/20/2018] [Accepted: 05/07/2018] [Indexed: 12/27/2022] Open
Abstract
Serine/arginine (SR)-rich proteins are critical for the regulation of alternative splicing (AS), which generates multiple mRNA isoforms from one gene and provides protein diversity for cell differentiation and tissue development. Genetic evidence suggests that Drosophila genital-specific overexpression of SR-related nuclear matrix protein of 160 kDa (SRm160), an SR protein with a PWI RNA-binding motif, causes defective development only in male flies and results in abnormal male genital structures and abnormal testis. However, the molecular characterization of SRm160 is limited. Using the high-throughput sequencing of RNA isolated by crosslinking immunoprecipitation (HITS-CLIP) method in two sex-specific embryonic cell lines, S2 from the male and Kc from the female, we first identified the genome-wide RNA-binding characteristics of SRm160, which preferred binding to the exonic tri-nucleotide repeats GCA and AAC. We then validated this binding through both in vitro gel-shift assay and in vivo splicing of minigenes and found that SRm160 level affects AS of many transcripts. Furthermore, we identified 492 differential binding sites (DBS) of SRm160 varying between the two sex-specific cell lines. Among these DBS-containing genes, splicing factors were highly enriched, including transformer, a key regulator in the sex determination cascade. Analyses of fly mutants demonstrated that the SRm160 level affects AS isoforms of transformer. These findings shed crucial light on SRm160's RNA-binding specificity and regulation of AS in Drosophila sex determination and development.
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Affiliation(s)
- Chen Qiu
- CAS Key Laboratory of Insect Developmental and Evolutionary Biology, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China.,University of Chinese Academy of Sciences, Shanghai, China
| | - Yu Zhang
- CAS Key Laboratory of Insect Developmental and Evolutionary Biology, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China.,University of Chinese Academy of Sciences, Shanghai, China
| | - Yu-Jie Fan
- CAS Key Laboratory of Insect Developmental and Evolutionary Biology, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China.,CAS Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, Shanghai, China
| | - Ting-Lin Pang
- CAS Key Laboratory of Insect Developmental and Evolutionary Biology, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China.,University of Chinese Academy of Sciences, Shanghai, China
| | - Yan Su
- CAS Key Laboratory of Insect Developmental and Evolutionary Biology, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China.,CAS Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, Shanghai, China
| | - Shuai Zhan
- CAS Key Laboratory of Insect Developmental and Evolutionary Biology, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China.,University of Chinese Academy of Sciences, Shanghai, China.,CAS Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Yong-Zhen Xu
- CAS Key Laboratory of Insect Developmental and Evolutionary Biology, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China.,University of Chinese Academy of Sciences, Shanghai, China.,CAS Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, Shanghai, China
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13
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Vester K, Santos KF, Kuropka B, Weise C, Wahl MC. The inactive C-terminal cassette of the dual-cassette RNA helicase BRR2 both stimulates and inhibits the activity of the N-terminal helicase unit. J Biol Chem 2019; 295:2097-2112. [PMID: 31914407 DOI: 10.1074/jbc.ra119.010964] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Revised: 12/27/2019] [Indexed: 11/06/2022] Open
Abstract
The RNA helicase bad response to refrigeration 2 homolog (BRR2) is required for the activation of the spliceosome before the first catalytic step of RNA splicing. BRR2 represents a distinct subgroup of Ski2-like nucleic acid helicases whose members comprise tandem helicase cassettes. Only the N-terminal cassette of BRR2 is an active ATPase and can unwind substrate RNAs. The C-terminal cassette represents a pseudoenzyme that can stimulate RNA-related activities of the N-terminal cassette. However, the molecular mechanisms by which the C-terminal cassette modulates the activities of the N-terminal unit remain elusive. Here, we show that N- and C-terminal cassettes adopt vastly different relative orientations in a crystal structure of BRR2 in complex with an activating domain of the spliceosomal Prp8 protein at 2.4 Å resolution compared with the crystal structure of BRR2 alone. Likewise, inspection of BRR2 structures within spliceosomal complexes revealed that the cassettes occupy different relative positions and engage in different intercassette contacts during different splicing stages. Engineered disulfide bridges that locked the cassettes in two different relative orientations had opposite effects on the RNA-unwinding activity of the N-terminal cassette, with one configuration enhancing and the other configuration inhibiting RNA unwinding compared with the unconstrained protein. Moreover, we found that differences in relative positioning of the cassettes strongly influence RNA-stimulated ATP hydrolysis by the N-terminal cassette. Our results indicate that the inactive C-terminal cassette of BRR2 can both positively and negatively affect the activity of the N-terminal helicase unit from a distance.
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Affiliation(s)
- Karen Vester
- Structural Biochemistry Group, Department of Biochemistry, Freie Universität Berlin, Takustrasse 63, D-14195 Berlin, Germany
| | - Karine F Santos
- Structural Biochemistry Group, Department of Biochemistry, Freie Universität Berlin, Takustrasse 63, D-14195 Berlin, Germany
| | - Benno Kuropka
- Protein Biochemistry Group, Department of Biochemistry, Freie Universität Berlin, Thielallee 63, D-14195 Berlin, Germany
| | - Christoph Weise
- Protein Biochemistry Group, Department of Biochemistry, Freie Universität Berlin, Thielallee 63, D-14195 Berlin, Germany
| | - Markus C Wahl
- Structural Biochemistry Group, Department of Biochemistry, Freie Universität Berlin, Takustrasse 63, D-14195 Berlin, Germany; Macromolecular Crystallography Group, Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Strasse 15, D-12489 Berlin, Germany.
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14
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Roy SW, Bowser BA. Molecular Evolution: RNA Splicing Machinery Moonlights in Junk Removal. Curr Biol 2019; 29:R920-R922. [PMID: 31593665 DOI: 10.1016/j.cub.2019.08.046] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A close relative of vertebrates solves the problem of gene-disrupting transposable element insertions by splicing them out at the RNA level. Why is such an elegant solution so rare across eukaryotes?
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Affiliation(s)
- Scott W Roy
- Department of Biology, San Francisco State University, San Francisco, CA 94132, USA; Molecular Cell Biology, University of California-Merced, Merced, CA 95343, USA.
| | - Bradley A Bowser
- Molecular Cell Biology, University of California-Merced, Merced, CA 95343, USA
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15
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Talkish J, Igel H, Hunter O, Horner SW, Jeffery NN, Leach JR, Jenkins JL, Kielkopf CL, Ares M. Cus2 enforces the first ATP-dependent step of splicing by binding to yeast SF3b1 through a UHM-ULM interaction. RNA (NEW YORK, N.Y.) 2019; 25:1020-1037. [PMID: 31110137 PMCID: PMC6633205 DOI: 10.1261/rna.070649.119] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Accepted: 05/15/2019] [Indexed: 05/16/2023]
Abstract
Stable recognition of the intron branchpoint (BP) by the U2 snRNP to form the pre-spliceosome is the first ATP-dependent step of splicing. Genetic and biochemical data from yeast indicate that Cus2 aids U2 snRNA folding into the stem IIa conformation prior to pre-spliceosome formation. Cus2 must then be removed by an ATP-dependent function of Prp5 before assembly can progress. However, the location from which Cus2 is displaced and the nature of its binding to the U2 snRNP are unknown. Here, we show that Cus2 contains a conserved UHM (U2AF homology motif) that binds Hsh155, the yeast homolog of human SF3b1, through a conserved ULM (U2AF ligand motif). Mutations in either motif block binding and allow pre-spliceosome formation without ATP. A 2.0 Å resolution structure of the Hsh155 ULM in complex with the UHM of Tat-SF1, the human homolog of Cus2, and complementary binding assays show that the interaction is highly similar between yeast and humans. Furthermore, we show that Tat-SF1 can replace Cus2 function by enforcing ATP dependence of pre-spliceosome formation in yeast extracts. Cus2 is removed before pre-spliceosome formation, and both Cus2 and its Hsh155 ULM binding site are absent from available cryo-EM structure models. However, our data are consistent with the apparent location of the disordered Hsh155 ULM between the U2 stem-loop IIa and the HEAT repeats of Hsh155 that interact with Prp5. We propose a model in which Prp5 uses ATP to remove Cus2 from Hsh155 such that extended base-pairing between U2 snRNA and the intron BP can occur.
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Affiliation(s)
- Jason Talkish
- Center for Molecular Biology of RNA, University of California, Santa Cruz, Santa Cruz, California 95064, USA
| | - Haller Igel
- Center for Molecular Biology of RNA, University of California, Santa Cruz, Santa Cruz, California 95064, USA
| | - Oarteze Hunter
- Center for Molecular Biology of RNA, University of California, Santa Cruz, Santa Cruz, California 95064, USA
| | - Steven W Horner
- Center for RNA Biology, Department of Biochemistry and Biophysics, University of Rochester School of Medicine and Dentistry, Rochester, New York 14642, USA
| | - Nazish N Jeffery
- Center for RNA Biology, Department of Biochemistry and Biophysics, University of Rochester School of Medicine and Dentistry, Rochester, New York 14642, USA
| | - Justin R Leach
- Center for RNA Biology, Department of Biochemistry and Biophysics, University of Rochester School of Medicine and Dentistry, Rochester, New York 14642, USA
| | - Jermaine L Jenkins
- Center for RNA Biology, Department of Biochemistry and Biophysics, University of Rochester School of Medicine and Dentistry, Rochester, New York 14642, USA
| | - Clara L Kielkopf
- Center for RNA Biology, Department of Biochemistry and Biophysics, University of Rochester School of Medicine and Dentistry, Rochester, New York 14642, USA
| | - Manuel Ares
- Center for Molecular Biology of RNA, University of California, Santa Cruz, Santa Cruz, California 95064, USA
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16
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An Allosteric Network for Spliceosome Activation Revealed by High-Throughput Suppressor Analysis in Saccharomyces cerevisiae. Genetics 2019; 212:111-124. [PMID: 30898770 DOI: 10.1534/genetics.119.301922] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2019] [Accepted: 03/15/2019] [Indexed: 12/30/2022] Open
Abstract
Selection of suppressor mutations that correct growth defects caused by substitutions in an RNA or protein can reveal functionally important molecular structures and interactions in living cells. This approach is particularly useful for the study of complex biological pathways involving many macromolecules, such as premessenger RNA (pre-mRNA) splicing. When a sufficiently large number of suppressor mutations is obtained and structural information is available, it is possible to generate detailed models of molecular function. However, the laborious and expensive task of identifying suppressor mutations in whole-genome selections limits the utility of this approach. Here I show that a custom targeted sequencing panel can greatly accelerate the identification of suppressor mutations in the Saccharomyces cerevisiae genome. Using a panel that targets 112 genes encoding pre-mRNA splicing factors, I identified 27 unique mutations in six protein-coding genes that each overcome the cold-sensitive block to spliceosome activation caused by a substitution in U4 small nuclear RNA. When mapped to existing structures of spliceosomal complexes, the identified suppressors implicate specific molecular contacts between the proteins Brr2, Prp6, Prp8, Prp31, Sad1, and Snu114 as functionally important in an early step of catalytic activation of the spliceosome. This approach shows great promise for elucidating the allosteric cascade of molecular interactions that direct accurate and efficient pre-mRNA splicing and should be broadly useful for understanding the dynamics of other complex biological assemblies or pathways.
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17
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Vijayakumari D, Sharma AK, Bawa PS, Kumar R, Srinivasan S, Vijayraghavan U. Early splicing functions of fission yeast Prp16 and its unexpected requirement for gene Silencing is governed by intronic features. RNA Biol 2019; 16:754-769. [PMID: 30810475 DOI: 10.1080/15476286.2019.1585737] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
Abstract
Prp16 is a DEAH box pre-mRNA splicing factor that triggers a key spliceosome conformational switch to facilitate second step splicing in Saccharomyces cerevisiae. However, Prp16 functions are largely unexplored in Schizosaccharomyces pombe, an attractive model with exon-intron architecture more relevant to several other eukaryotes. Here, we generated mis-sense alleles in SpPrp16 whose consequences on genome-wide splicing uncover its nearly global splicing role with only a small subset of unaffected introns. Prp16 dependent and independent intron categories displayed a striking difference in the strength of intronic 5' splice site (5'SS)-U6 snRNA and branch site (BS)-U2 snRNA interactions. Selective weakening of these interactions could convert a Prp16 dependent intron into an independent one. These results point to the role of SpPrp16 in destabilizing 5'SS-U6snRNA and BS-U2snRNA interactions which plausibly trigger structural alterations in the spliceosome to facilitate first step catalysis. Our data suggest that SpPrp16 interactions with early acting factors, its enzymatic activities and association with intronic elements collectively account for efficient and accurate first step catalysis. In addition to splicing derangements in the spprp16F528S mutant, we show that SpPrp16 influences cell cycle progression and centromeric heterochromatinization. We propose that strong 5'SS-U6 snRNA and BS-U2 snRNA complementarity of intron-like elements in non-coding RNAs which lead to complete splicing arrest and impaired Seb1 functions at the pericentromeric loci may cumulatively account for the heterochromatin defects in spprp16F528S cells. These findings suggest that the diverse Prp16 functions within a genome are likely governed by its intronic features that influence splice site-snRNA interaction strength.
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Affiliation(s)
- Drisya Vijayakumari
- a Department of Microbiology and Cell Biology , Indian Institute of Science , Bangalore , India
| | - Amit Kumar Sharma
- a Department of Microbiology and Cell Biology , Indian Institute of Science , Bangalore , India
| | | | - Rakesh Kumar
- a Department of Microbiology and Cell Biology , Indian Institute of Science , Bangalore , India
| | | | - Usha Vijayraghavan
- a Department of Microbiology and Cell Biology , Indian Institute of Science , Bangalore , India
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18
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Mendel M, Chen KM, Homolka D, Gos P, Pandey RR, McCarthy AA, Pillai RS. Methylation of Structured RNA by the m 6A Writer METTL16 Is Essential for Mouse Embryonic Development. Mol Cell 2018; 71:986-1000.e11. [PMID: 30197299 PMCID: PMC6162343 DOI: 10.1016/j.molcel.2018.08.004] [Citation(s) in RCA: 211] [Impact Index Per Article: 35.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2018] [Revised: 06/22/2018] [Accepted: 07/30/2018] [Indexed: 12/19/2022]
Abstract
Internal modification of RNAs with N6-methyladenosine (m6A) is a highly conserved means of gene expression control. While the METTL3/METTL14 heterodimer adds this mark on thousands of transcripts in a single-stranded context, the substrate requirements and physiological roles of the second m6A writer METTL16 remain unknown. Here we describe the crystal structure of human METTL16 to reveal a methyltransferase domain furnished with an extra N-terminal module, which together form a deep-cut groove that is essential for RNA binding. When presented with a random pool of RNAs, METTL16 selects for methylation-structured RNAs where the critical adenosine is present in a bulge. Mouse 16-cell embryos lacking Mettl16 display reduced mRNA levels of its methylation target, the SAM synthetase Mat2a. The consequence is massive transcriptome dysregulation in ∼64-cell blastocysts that are unfit for further development. This highlights the role of an m6A RNA methyltransferase in facilitating early development via regulation of SAM availability. Structure of the METTL16 m6A writer domain with a unique N-terminal module N-terminal module of METTL16 is essential for charge-based binding to RNA METTL16 preferentially methylates adenosines within structured RNAs Regulation of Mat2a mRNA by Mettl16 is essential for mouse embryonic development
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Affiliation(s)
- Mateusz Mendel
- Department of Molecular Biology, Science III, University of Geneva, 30 Quai Ernest-Ansermet, CH-1211 Geneva 4, Switzerland
| | - Kuan-Ming Chen
- Department of Molecular Biology, Science III, University of Geneva, 30 Quai Ernest-Ansermet, CH-1211 Geneva 4, Switzerland
| | - David Homolka
- Department of Molecular Biology, Science III, University of Geneva, 30 Quai Ernest-Ansermet, CH-1211 Geneva 4, Switzerland
| | - Pascal Gos
- Department of Molecular Biology, Science III, University of Geneva, 30 Quai Ernest-Ansermet, CH-1211 Geneva 4, Switzerland
| | - Radha Raman Pandey
- Department of Molecular Biology, Science III, University of Geneva, 30 Quai Ernest-Ansermet, CH-1211 Geneva 4, Switzerland
| | - Andrew A McCarthy
- European Molecular Biology Laboratory, Grenoble Outstation, 71 Avenue des Martyrs, 38042 Grenoble, France
| | - Ramesh S Pillai
- Department of Molecular Biology, Science III, University of Geneva, 30 Quai Ernest-Ansermet, CH-1211 Geneva 4, Switzerland.
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19
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Didychuk AL, Butcher SE, Brow DA. The life of U6 small nuclear RNA, from cradle to grave. RNA (NEW YORK, N.Y.) 2018; 24:437-460. [PMID: 29367453 PMCID: PMC5855946 DOI: 10.1261/rna.065136.117] [Citation(s) in RCA: 67] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Removal of introns from precursor messenger RNA (pre-mRNA) and some noncoding transcripts is an essential step in eukaryotic gene expression. In the nucleus, this process of RNA splicing is carried out by the spliceosome, a multi-megaDalton macromolecular machine whose core components are conserved from yeast to humans. In addition to many proteins, the spliceosome contains five uridine-rich small nuclear RNAs (snRNAs) that undergo an elaborate series of conformational changes to correctly recognize the splice sites and catalyze intron removal. Decades of biochemical and genetic data, along with recent cryo-EM structures, unequivocally demonstrate that U6 snRNA forms much of the catalytic core of the spliceosome and is highly dynamic, interacting with three snRNAs, the pre-mRNA substrate, and >25 protein partners throughout the splicing cycle. This review summarizes the current state of knowledge on how U6 snRNA is synthesized, modified, incorporated into snRNPs and spliceosomes, recycled, and degraded.
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Affiliation(s)
- Allison L Didychuk
- Department of Biochemistry, University of Wisconsin, Madison, Wisconsin 53706, USA
| | - Samuel E Butcher
- Department of Biochemistry, University of Wisconsin, Madison, Wisconsin 53706, USA
| | - David A Brow
- Department of Biomolecular Chemistry, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin 53706, USA
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20
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Studying structure and function of spliceosomal helicases. Methods 2017; 125:63-69. [PMID: 28668587 DOI: 10.1016/j.ymeth.2017.06.028] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Revised: 06/21/2017] [Accepted: 06/24/2017] [Indexed: 12/27/2022] Open
Abstract
The splicing of eukaryotic precursor mRNAs requires the activity of at least three DEAD-box helicases, one Ski2-like helicase and four DEAH-box helicases. High resolution structures for five of these spliceosomal helicases were obtained by means of X-ray crystallography. Additional low resolution structural information could be derived from single particle cryo electron microscopy and small angle X-ray scattering. The functional characterization includes biochemical methods to measure the ATPase and helicase activities. This review gives an overview on the techniques used to gain insights in to the structure and function of spliceosomal helicases.
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21
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Tang Q, Rodriguez-Santiago S, Wang J, Pu J, Yuste A, Gupta V, Moldón A, Xu YZ, Query CC. SF3B1/Hsh155 HEAT motif mutations affect interaction with the spliceosomal ATPase Prp5, resulting in altered branch site selectivity in pre-mRNA splicing. Genes Dev 2016; 30:2710-2723. [PMID: 28087715 PMCID: PMC5238730 DOI: 10.1101/gad.291872.116] [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: 10/10/2016] [Accepted: 12/12/2016] [Indexed: 11/25/2022]
Abstract
Mutations in the U2 snRNP component SF3B1 are prominent in myelodysplastic syndromes (MDSs) and other cancers and have been shown recently to alter branch site (BS) or 3' splice site selection in splicing. However, the molecular mechanism of altered splicing is not known. We show here that hsh155 mutant alleles in Saccharomyces cerevisiae, counterparts of SF3B1 mutations frequently found in cancers, specifically change splicing of suboptimal BS pre-mRNA substrates. We found that Hsh155p interacts directly with Prp5p, the first ATPase that acts during spliceosome assembly, and localized the interacting regions to HEAT (Huntingtin, EF3, PP2A, and TOR1) motifs in SF3B1 associated with disease mutations. Furthermore, we show that mutations in these motifs from both human disease and yeast genetic screens alter the physical interaction with Prp5p, alter branch region specification, and phenocopy mutations in Prp5p. These and other data demonstrate that mutations in Hsh155p and Prp5p alter splicing because they change the direct physical interaction between Hsh155p and Prp5p. This altered physical interaction results in altered loading (i.e., "fidelity") of the BS-U2 duplex into the SF3B complex during prespliceosome formation. These results provide a mechanistic framework to explain the consequences of intron recognition and splicing of SF3B1 mutations found in disease.
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Affiliation(s)
- Qing Tang
- Key Laboratory of Insect Developmental and Evolutionary Biology, CAS Center for Excellence in Molecular Cell Science, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032 China
| | | | - Jing Wang
- Key Laboratory of Insect Developmental and Evolutionary Biology, CAS Center for Excellence in Molecular Cell Science, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032 China
| | - Jia Pu
- Key Laboratory of Insect Developmental and Evolutionary Biology, CAS Center for Excellence in Molecular Cell Science, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032 China
| | - Andrea Yuste
- Department of Cell Biology, Albert Einstein College of Medicine, Bronx, New York 10461 USA
| | - Varun Gupta
- Department of Cell Biology, Albert Einstein College of Medicine, Bronx, New York 10461 USA
| | - Alberto Moldón
- Department of Cell Biology, Albert Einstein College of Medicine, Bronx, New York 10461 USA
| | - Yong-Zhen Xu
- Key Laboratory of Insect Developmental and Evolutionary Biology, CAS Center for Excellence in Molecular Cell Science, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032 China
| | - Charles C Query
- Department of Cell Biology, Albert Einstein College of Medicine, Bronx, New York 10461 USA
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22
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Absmeier E, Santos KF, Wahl MC. Functions and regulation of the Brr2 RNA helicase during splicing. Cell Cycle 2016; 15:3362-3377. [PMID: 27792457 DOI: 10.1080/15384101.2016.1249549] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Pre-mRNA splicing entails the stepwise assembly of an inactive spliceosome, its catalytic activation, splicing catalysis and spliceosome disassembly. Transitions in this reaction cycle are accompanied by compositional and conformational rearrangements of the underlying RNA-protein interaction networks, which are driven and controlled by 8 conserved superfamily 2 RNA helicases. The Ski2-like helicase, Brr2, provides the key remodeling activity during spliceosome activation and is additionally implicated in the catalytic and disassembly phases of splicing, indicating that Brr2 needs to be tightly regulated during splicing. Recent structural and functional analyses have begun to unravel how Brr2 regulation is established via multiple layers of intra- and inter-molecular mechanisms. Brr2 has an unusual structure, including a long N-terminal region and a catalytically inactive C-terminal helicase cassette, which can auto-inhibit and auto-activate the enzyme, respectively. Both elements are essential, also serve as protein-protein interaction devices and the N-terminal region is required for stable Brr2 association with the tri-snRNP, tri-snRNP stability and retention of U5 and U6 snRNAs during spliceosome activation in vivo. Furthermore, a C-terminal region of the Prp8 protein, comprising consecutive RNase H-like and Jab1/MPN-like domains, can both up- and down-regulate Brr2 activity. Biochemical studies revealed an intricate cross-talk among the various cis- and trans-regulatory mechanisms. Comparison of isolated Brr2 to electron cryo-microscopic structures of yeast and human U4/U6•U5 tri-snRNPs and spliceosomes indicates how some of the regulatory elements exert their functions during splicing. The various modulatory mechanisms acting on Brr2 might be exploited to enhance splicing fidelity and to regulate alternative splicing.
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Affiliation(s)
- Eva Absmeier
- a Freie Universität Berlin, Laboratory of Structural Biochemistry , Berlin , Germany
| | - Karine F Santos
- a Freie Universität Berlin, Laboratory of Structural Biochemistry , Berlin , Germany
| | - Markus C Wahl
- a Freie Universität Berlin, Laboratory of Structural Biochemistry , Berlin , Germany.,b Helmholtz-Zentrum Berlin für Materialien und Energie, Macromolecular Crystallography , Berlin , Germany
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23
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Boesler C, Rigo N, Anokhina MM, Tauchert MJ, Agafonov DE, Kastner B, Urlaub H, Ficner R, Will CL, Lührmann R. A spliceosome intermediate with loosely associated tri-snRNP accumulates in the absence of Prp28 ATPase activity. Nat Commun 2016; 7:11997. [PMID: 27377154 PMCID: PMC4935976 DOI: 10.1038/ncomms11997] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2015] [Accepted: 05/20/2016] [Indexed: 11/17/2022] Open
Abstract
The precise role of the spliceosomal DEAD-box protein Prp28 in higher eukaryotes remains unclear. We show that stable tri-snRNP association during pre-catalytic spliceosomal B complex formation is blocked by a dominant-negative hPrp28 mutant lacking ATPase activity. Complexes formed in the presence of ATPase-deficient hPrp28 represent a novel assembly intermediate, the pre-B complex, that contains U1, U2 and loosely associated tri-snRNP and is stalled before disruption of the U1/5′ss base pairing interaction, consistent with a role for hPrp28 in the latter. Pre-B and B complexes differ structurally, indicating that stable tri-snRNP integration is accompanied by substantial rearrangements in the spliceosome. Disruption of the U1/5′ss interaction alone is not sufficient to bypass the block by ATPase-deficient hPrp28, suggesting hPrp28 has an additional function at this stage of splicing. Our data provide new insights into the function of Prp28 in higher eukaryotes, and the requirements for stable tri-snRNP binding during B complex formation. The assembly of the splicesome involves several distinct stages that require the sequential action of DExD/H-box RNA helicases. Here, the authors uncover a new intermediate, the pre-B complex, that accumulates in the presence of an inactive form of the DEAD-box protein Prp28.
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Affiliation(s)
- Carsten Boesler
- Department of Cellular Biochemistry, MPI for Biophysical Chemistry, Am Fassberg 11, D-37077 Göttingen, Germany
| | - Norbert Rigo
- Department of Cellular Biochemistry, MPI for Biophysical Chemistry, Am Fassberg 11, D-37077 Göttingen, Germany
| | - Maria M Anokhina
- Department of Cellular Biochemistry, MPI for Biophysical Chemistry, Am Fassberg 11, D-37077 Göttingen, Germany
| | - Marcel J Tauchert
- Department of Molecular Structural Biology, Institute for Microbiology and Genetics, GZMB, Georg-August-Universität Göttingen, Justus-von-Liebig-Weg 11, D-37077 Göttingen, Germany
| | - Dmitry E Agafonov
- Department of Cellular Biochemistry, MPI for Biophysical Chemistry, Am Fassberg 11, D-37077 Göttingen, Germany
| | - Berthold Kastner
- Department of Cellular Biochemistry, MPI for Biophysical Chemistry, Am Fassberg 11, D-37077 Göttingen, Germany
| | - Henning Urlaub
- Bioanalytical Mass Spectrometry Group, MPI for Biophysical Chemistry, Am Fassberg 11, D-37077 Göttingen, Germany.,Bioanalytics Group, Institute for Clinical Chemistry, University Medical Center Göttingen, Robert-Koch-Straße 40, D-37075 Göttingen, Germany
| | - Ralf Ficner
- Department of Molecular Structural Biology, Institute for Microbiology and Genetics, GZMB, Georg-August-Universität Göttingen, Justus-von-Liebig-Weg 11, D-37077 Göttingen, Germany
| | - Cindy L Will
- Department of Cellular Biochemistry, MPI for Biophysical Chemistry, Am Fassberg 11, D-37077 Göttingen, Germany
| | - Reinhard Lührmann
- Department of Cellular Biochemistry, MPI for Biophysical Chemistry, Am Fassberg 11, D-37077 Göttingen, Germany
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Hoskins AA, Rodgers ML, Friedman LJ, Gelles J, Moore MJ. Single molecule analysis reveals reversible and irreversible steps during spliceosome activation. eLife 2016; 5. [PMID: 27244240 PMCID: PMC4922858 DOI: 10.7554/elife.14166] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2016] [Accepted: 05/26/2016] [Indexed: 12/19/2022] Open
Abstract
The spliceosome is a complex machine composed of small nuclear ribonucleoproteins (snRNPs) and accessory proteins that excises introns from pre-mRNAs. After assembly the spliceosome is activated for catalysis by rearrangement of subunits to form an active site. How this rearrangement is coordinated is not well-understood. During activation, U4 must be released to allow U6 conformational change, while Prp19 complex (NTC) recruitment is essential for stabilizing the active site. We used multi-wavelength colocalization single molecule spectroscopy to directly observe the key events in Saccharomyces cerevisiae spliceosome activation. Following binding of the U4/U6.U5 tri-snRNP, the spliceosome either reverses assembly by discarding tri-snRNP or proceeds to activation by irreversible U4 loss. The major pathway for NTC recruitment occurs after U4 release. ATP stimulates both the competing U4 release and tri-snRNP discard processes. The data reveal the activation mechanism and show that overall splicing efficiency may be maintained through repeated rounds of disassembly and tri-snRNP reassociation. DOI:http://dx.doi.org/10.7554/eLife.14166.001 The genes in an organism’s DNA may be expressed to form a protein via an intermediate molecule called RNA. In many organisms including humans, gene expression often begins by making a precursor molecule called a pre-mRNA. The pre-mRNA contains regions called exons that code for the protein product and regions called introns that do not. A machine in the cell called the spliceosome has the job of removing the introns in the pre-mRNA and stitching the exons together by a process known as splicing. The spliceosome is made up of dozens of components that assemble on the pre-mRNAs. Before a newly assembled spliceosome can carry out splicing, it must be activated. The activation process involves several steps that are powered by the cell's universal power source (a molecule called ATP), including the release of many components from the spliceosome. Many of the details of the activation process are unclear. Spliceosomes in the yeast species Saccharomyces cerevisiae are similar to spliceosomes from humans, and so are often studied experimentally. Hoskins et al. have now used a technique called colocalization single molecule fluorescence spectroscopy to follow, in real time, a single yeast spliceosome molecule as it activates. This technique uses a specialized microscope and a number of colored lasers to detect different spliceosome proteins at the same time. Hoskins et al. found that one of the steps during activation is irreversible – once that step occurs, the spliceosome must either perform the next activation steps or start the processes of assembly and activation over again. Hoskins et al. also discovered that ATP causes some spliceosomes to be discarded during activation and not used for splicing. This indicates that before spliceosomes are allowed to activate, they may undergo 'quality control', which may be important for making sure that gene expression occurs efficiently and correctly. Future studies will investigate how this quality control process works in further detail. DOI:http://dx.doi.org/10.7554/eLife.14166.002
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Affiliation(s)
- Aaron A Hoskins
- Department of Biochemistry, University of Wisconsin-Madison, Madison, United States
| | - Margaret L Rodgers
- Department of Biochemistry, University of Wisconsin-Madison, Madison, United States
| | - Larry J Friedman
- Department of Biochemistry, Brandeis University, Waltham, United States
| | - Jeff Gelles
- Department of Biochemistry, Brandeis University, Waltham, United States
| | - Melissa J Moore
- Department of Biochemistry and Molecular Pharmacology, Howard Hughes Medical Institute, University of Massachusetts Medical School, Worcester, United States
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Tauchert MJ, Ficner R. Structural analysis of the spliceosomal RNA helicase Prp28 from the thermophilic eukaryote Chaetomium thermophilum. Acta Crystallogr F Struct Biol Commun 2016; 72:409-16. [PMID: 27139834 PMCID: PMC4854570 DOI: 10.1107/s2053230x16006038] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2016] [Accepted: 04/11/2016] [Indexed: 11/10/2022] Open
Abstract
Prp28 (pre-mRNA-splicing ATP-dependent RNA helicase 28) is a spliceosomal DEAD-box helicase which is involved in two steps of spliceosome assembly. It is required for the formation of commitment complex 2 in an ATP-independent manner as well as for the formation of the pre-catalytic spliceosome, which in contrast is ATP-dependent. During the latter step, Prp28 is crucial for the integration of the U4/U6·U5 tri-snRNP since it displaces the U1 snRNP and allows the U6 snRNP to base-pair with the 5'-splice site. Here, the crystal structure of Prp28 from the thermophilic fungus Chaetomium thermophilum is reported at 3.2 Å resolution and is compared with the available structures of homologues.
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Affiliation(s)
- Marcel J. Tauchert
- Department of Molecular Structural Biology, Institute for Microbiology and Genetics, GZMB, Georg-August-University Göttingen, Justus-von-Liebig Weg 11, 37077 Göttingen, Germany
| | - Ralf Ficner
- Department of Molecular Structural Biology, Institute for Microbiology and Genetics, GZMB, Georg-August-University Göttingen, Justus-von-Liebig Weg 11, 37077 Göttingen, Germany
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26
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De I, Schmitzová J, Pena V. The organization and contribution of helicases to RNA splicing. WILEY INTERDISCIPLINARY REVIEWS-RNA 2016; 7:259-74. [PMID: 26874649 DOI: 10.1002/wrna.1331] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2015] [Revised: 12/08/2015] [Accepted: 12/09/2015] [Indexed: 12/27/2022]
Abstract
Splicing is an essential step of gene expression. It occurs in two consecutive chemical reactions catalyzed by a large protein-RNA complex named the spliceosome. Assembled on the pre-mRNA substrate from five small nuclear proteins, the spliceosome acts as a protein-controlled ribozyme to catalyze the two reactions and finally dissociates into its components, which are re-used for a new round of splicing. Upon following this cyclic pathway, the spliceosome undergoes numerous intermediate stages that differ in composition as well as in their internal RNA-RNA and RNA-protein contacts. The driving forces and control mechanisms of these remodeling processes are provided by specific molecular motors called RNA helicases. While eight spliceosomal helicases are present in all organisms, higher eukaryotes contain five additional ones potentially required to drive a more intricate splicing pathway and link it to an RNA metabolism of increasing complexity. Spliceosomal helicases exhibit a notable structural diversity in their accessory domains and overall architecture, in accordance with the diversity of their task-specific functions. This review summarizes structure-function knowledge about all spliceosomal helicases, including the latter five, which traditionally are treated separately from the conserved ones. The implications of the structural characteristics of helicases for their functions, as well as for their structural communication within the multi-subunits environment of the spliceosome, are pointed out.
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Affiliation(s)
- Inessa De
- Macromolecular Crystallography Group, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Jana Schmitzová
- Macromolecular Crystallography Group, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Vladimir Pena
- Macromolecular Crystallography Group, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
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27
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Liu YC, Cheng SC. Functional roles of DExD/H-box RNA helicases in Pre-mRNA splicing. J Biomed Sci 2015; 22:54. [PMID: 26173448 PMCID: PMC4503299 DOI: 10.1186/s12929-015-0161-z] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2015] [Accepted: 06/29/2015] [Indexed: 01/30/2023] Open
Abstract
Splicing of precursor mRNA takes place via two consecutive steps of transesterification catalyzed by a large ribonucleoprotein complex called the spliceosome. The spliceosome is assembled through ordered binding to the pre-mRNA of five small nuclear RNAs and numerous protein factors, and is disassembled after completion of the reaction to recycle all components. Throughout the splicing cycle, the spliceosome changes its structure, rearranging RNA-RNA, RNA-protein and protein-protein interactions, for positioning and repositioning of splice sites. DExD/H-box RNA helicases play important roles in mediating structural changes of the spliceosome by unwinding of RNA duplexes or disrupting RNA-protein interactions. DExD/H-box proteins are also implicated in the fidelity control of the splicing process at various steps. This review summarizes the functional roles of DExD/H-box proteins in pre-mRNA splicing according to studies conducted mostly in yeast and will discuss the concept of the complicated splicing reaction based on recent findings.
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Affiliation(s)
- Yen-Chi Liu
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan, 115, Republic of China.
| | - Soo-Chen Cheng
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan, 115, Republic of China.
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28
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Gao JL, Fan YJ, Wang XY, Zhang Y, Pu J, Li L, Shao W, Zhan S, Hao J, Xu YZ. A conserved intronic U1 snRNP-binding sequence promotes trans-splicing in Drosophila. Genes Dev 2015; 29:760-71. [PMID: 25838544 PMCID: PMC4387717 DOI: 10.1101/gad.258863.115] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Gao et al. investigate mod(mdg4), a classic trans-spliced gene in Drosophila, and report that two critical RNA sequences in the middle of the last 5′ intron, TSA and TSB, promote trans-splicing of mod(mdg4). In TSA, a 13-nt core motif is conserved across Drosophila species and is essential and sufficient for trans-splicing, which binds U1 snRNP through strong base-pairing with U1 snRNA. In TSB, a conserved secondary structure acts as an enhancer. Deletions of TSA and TSB result in developmental defects in flies. Unlike typical cis-splicing, trans-splicing joins exons from two separate transcripts to produce chimeric mRNA and has been detected in most eukaryotes. Trans-splicing in trypanosomes and nematodes has been characterized as a spliced leader RNA-facilitated reaction; in contrast, its mechanism in higher eukaryotes remains unclear. Here we investigate mod(mdg4), a classic trans-spliced gene in Drosophila, and report that two critical RNA sequences in the middle of the last 5′ intron, TSA and TSB, promote trans-splicing of mod(mdg4). In TSA, a 13-nucleotide (nt) core motif is conserved across Drosophila species and is essential and sufficient for trans-splicing, which binds U1 small nuclear RNP (snRNP) through strong base-pairing with U1 snRNA. In TSB, a conserved secondary structure acts as an enhancer. Deletions of TSA and TSB using the CRISPR/Cas9 system result in developmental defects in flies. Although it is not clear how the 5′ intron finds the 3′ introns, compensatory changes in U1 snRNA rescue trans-splicing of TSA mutants, demonstrating that U1 recruitment is critical to promote trans-splicing in vivo. Furthermore, TSA core-like motifs are found in many other trans-spliced Drosophila genes, including lola. These findings represent a novel mechanism of trans-splicing, in which RNA motifs in the 5′ intron are sufficient to bring separate transcripts into close proximity to promote trans-splicing.
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Affiliation(s)
- Jun-Li Gao
- Key Laboratory of Insect Developmental and Evolutionary Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China
| | - Yu-Jie Fan
- Key Laboratory of Insect Developmental and Evolutionary Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China
| | - Xiu-Ye Wang
- Key Laboratory of Insect Developmental and Evolutionary Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China
| | - Yu Zhang
- Key Laboratory of Insect Developmental and Evolutionary Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China
| | - Jia Pu
- Key Laboratory of Insect Developmental and Evolutionary Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China
| | - Liang Li
- Key Laboratory of Insect Developmental and Evolutionary Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China
| | - Wei Shao
- Key Laboratory of Insect Developmental and Evolutionary Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China
| | - Shuai Zhan
- Key Laboratory of Insect Developmental and Evolutionary Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China
| | | | - Yong-Zhen Xu
- Key Laboratory of Insect Developmental and Evolutionary Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China;
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Absmeier E, Rosenberger L, Apelt L, Becke C, Santos KF, Stelzl U, Wahl MC. A noncanonical PWI domain in the N-terminal helicase-associated region of the spliceosomal Brr2 protein. ACTA ACUST UNITED AC 2015; 71:762-71. [DOI: 10.1107/s1399004715001005] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2014] [Accepted: 01/16/2015] [Indexed: 11/10/2022]
Abstract
The spliceosomal RNA helicase Brr2 is required for the assembly of a catalytically active spliceosome on a messenger RNA precursor. Brr2 exhibits an unusual organization with tandem helicase units, each comprising dual RecA-like domains and a Sec63 homology unit, preceded by a more than 400-residue N-terminal helicase-associated region. Whereas recent crystal structures have provided insights into the molecular architecture and regulation of the Brr2 helicase region, little is known about the structural organization and function of its N-terminal part. Here, a near-atomic resolution crystal structure of a PWI-like domain that resides in the N-terminal region ofChaetomium thermophilumBrr2 is presented. CD spectroscopic studies suggested that this domain is conserved in the yeast and human Brr2 orthologues. Although canonical PWI domains act as low-specificity nucleic acid-binding domains, no significant affinity of the unusual PWI domain of Brr2 for a broad spectrum of DNAs and RNAs was detected in band-shift assays. Consistently, theC. thermophilumBrr2 PWI-like domain, in the conformation seen in the present crystal structure, lacks an expanded positively charged surface patch as observed in at least one canonical, nucleic acid-binding PWI domain. Instead, in a comprehensive yeast two-hybrid screen against human spliceosomal proteins, fragments of the N-terminal region of human Brr2 were found to interact with several other spliceosomal proteins. At least one of these interactions, with the Prp19 complex protein SPF27, depended on the presence of the PWI-like domain. The results suggest that the N-terminal region of Brr2 serves as a versatile protein–protein interaction platform in the spliceosome and that some interactions require or are reinforced by the PWI-like domain.
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30
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Pan K, Lee JTH, Huang Z, Wong CM. Coupling and coordination in gene expression processes with pre-mRNA splicing. Int J Mol Sci 2015; 16:5682-96. [PMID: 25768347 PMCID: PMC4394499 DOI: 10.3390/ijms16035682] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2014] [Revised: 02/28/2015] [Accepted: 03/04/2015] [Indexed: 12/13/2022] Open
Abstract
RNA processing is a tightly regulated and highly complex pathway which includes transcription, splicing, editing, transportation, translation and degradation. It has been well-documented that splicing of RNA polymerase II medicated nascent transcripts occurs co-transcriptionally and is functionally coupled to other RNA processing. Recently, increasing experimental evidence indicated that pre-mRNA splicing influences RNA degradation and vice versa. In this review, we summarized the recent findings demonstrating the coupling of these two processes. In addition, we highlighted the importance of splicing in the production of intronic miRNA and circular RNAs, and hence the discovery of the novel mechanisms in the regulation of gene expression.
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31
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Liang WW, Cheng SC. A novel mechanism for Prp5 function in prespliceosome formation and proofreading the branch site sequence. Genes Dev 2015; 29:81-93. [PMID: 25561497 PMCID: PMC4281567 DOI: 10.1101/gad.253708.114] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The DEAD-box RNA helicase Prp5 is required for the formation of the prespliceosome through an ATP-dependent function to remodel U2 snRNPs and an ATP-independent function of unknown mechanism. Liang and Cheng show that Prp5 binds to the spliceosome in association with U2 by interacting with the branchpoint-interacting stem–loop and is released upon base-pairing of U2 with the branch site to allow the recruitment of the tri-snRNP. The DEAD-box RNA helicase Prp5 is required for the formation of the prespliceosome through an ATP-dependent function to remodel U2 small nuclear ribonucleoprotein particles (snRNPs) and an ATP-independent function of unknown mechanism. Prp5 has also been implicated in proofreading the branch site sequence, but the molecular mechanism has not been well characterized. Using actin precursor mRNA (pre-mRNA) carrying branch site mutations, we identified a Prp5-containing prespliceosome with Prp5 directly bound to U2 small nuclear RNA (snRNA). Prp5 is in contact with U2 in regions on and near the branchpoint-interacting stem–loop (BSL), suggesting that Prp5 may function in stabilizing the BSL. Regardless of its ATPase activity, Prp5 mutants that suppress branch site mutations associate with the spliceosome less tightly and allow more tri-snRNP binding for the reaction to proceed. Our results suggest a novel mechanism for how Prp5 functions in prespliceosome formation and proofreading of the branch site sequence. Prp5 binds to the spliceosome in association with U2 by interacting with the BSL and is released upon the base-pairing of U2 with the branch site to allow the recruitment of the tri-snRNP. Mutations impairing U2–branch site base-pairing retard Prp5 release and impede tri-snRNP association. Prp5 mutations that destabilize the Prp5–U2 interaction suppress branch site mutations by allowing progression of the pathway.
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Affiliation(s)
- Wen-Wei Liang
- Institute of Molecular Biology, Academia Sinica, Taipei 115, Taiwan; Institute of Microbiology and Immunology, National Yang-Ming University, Taipei 112, Taiwan
| | - Soo-Chen Cheng
- Institute of Molecular Biology, Academia Sinica, Taipei 115, Taiwan
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32
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Jacewicz A, Schwer B, Smith P, Shuman S. Crystal structure, mutational analysis and RNA-dependent ATPase activity of the yeast DEAD-box pre-mRNA splicing factor Prp28. Nucleic Acids Res 2014; 42:12885-98. [PMID: 25303995 PMCID: PMC4227776 DOI: 10.1093/nar/gku930] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Yeast Prp28 is a DEAD-box pre-mRNA splicing factor implicated in displacing U1 snRNP from the 5′ splice site. Here we report that the 588-aa Prp28 protein consists of a trypsin-sensitive 126-aa N-terminal segment (of which aa 1–89 are dispensable for Prp28 function in vivo) fused to a trypsin-resistant C-terminal catalytic domain. Purified recombinant Prp28 and Prp28-(127–588) have an intrinsic RNA-dependent ATPase activity, albeit with a low turnover number. The crystal structure of Prp28-(127–588) comprises two RecA-like domains splayed widely apart. AMPPNP•Mg2+ is engaged by the proximal domain, with proper and specific contacts from Phe194 and Gln201 (Q motif) to the adenine nucleobase. The triphosphate moiety of AMPPNP•Mg2+ is not poised for catalysis in the open domain conformation. Guided by the Prp28•AMPPNP structure, and that of the Drosophila Vasa•AMPPNP•Mg2+•RNA complex, we targeted 20 positions in Prp28 for alanine scanning. ATP-site components Asp341 and Glu342 (motif II) and Arg527 and Arg530 (motif VI) and RNA-site constituent Arg476 (motif Va) are essential for Prp28 activity in vivo. Synthetic lethality of double-alanine mutations highlighted functionally redundant contacts in the ATP-binding (Phe194-Gln201, Gln201-Asp502) and RNA-binding (Arg264-Arg320) sites. Overexpression of defective ATP-site mutants, but not defective RNA-site mutants, elicited severe dominant-negative growth defects.
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Affiliation(s)
- Agata Jacewicz
- Molecular Biology Program, Sloan-Kettering Institute, New York, NY 10065, USA
| | - Beate Schwer
- Microbiology and Immunology Department, Weill Cornell Medical College, New York, NY 10065, USA
| | - Paul Smith
- Molecular Biology Program, Sloan-Kettering Institute, New York, NY 10065, USA
| | - Stewart Shuman
- Molecular Biology Program, Sloan-Kettering Institute, New York, NY 10065, USA
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33
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Valdés J, Nozaki T, Sato E, Chiba Y, Nakada-Tsukui K, Villegas-Sepúlveda N, Winkler R, Azuara-Liceaga E, Mendoza-Figueroa MS, Watanabe N, Santos HJ, Saito-Nakano Y, Galindo-Rosales JM. Proteomic analysis of Entamoeba histolytica in vivo assembled pre-mRNA splicing complexes. J Proteomics 2014; 111:30-45. [PMID: 25109466 DOI: 10.1016/j.jprot.2014.07.027] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2014] [Revised: 06/27/2014] [Accepted: 07/23/2014] [Indexed: 10/24/2022]
Abstract
UNLABELLED The genome of the human intestinal parasite Entamoeba histolytica contains nearly 3000 introns and bioinformatic predictions indicate that major and minor spliceosomes occur in Entamoeba. However, except for the U2-, U4-, U5- and U6 snRNAs, no other splicing factor has been cloned and characterized. Here, we HA-tagged cloned the snRNP component U1A and assessed its expression and nuclear localization. Because the snRNP-free U1A form interacts with polyadenylate-binding protein, HA-U1A immunoprecipitates could identify early and late splicing complexes. Avoiding Entamoeba's endonucleases and ensuring the precipitation of RNA-binding proteins, parasite cultures were UV cross-linked prior to nuclear fraction immunoprecipitations with HA antibodies, and precipitates were subjected to tandem mass spectrometry (MS/MS) analyses. To discriminate their nuclear roles (chromatin-, co-transcriptional-, splicing-related), MS/MS analyses were carried out with proteins eluted with MS2-GST-sepharose from nuclear extracts of an MS2 aptamer-tagged Rabx13 intron amoeba transformant. Thus, we probed thirty-six Entamoeba proteins corresponding to 32 cognate splicing-specific factors, including 13 DExH/D helicases required for all stages of splicing, and 12 different splicing-related helicases were identified also. Furthermore 50 additional proteins, possibly involved in co-transcriptional processes were identified, revealing the complexity of co-transcriptional splicing in Entamoeba. Some of these later factors were not previously found in splicing complex analyses. BIOLOGICAL SIGNIFICANCE Numerous facts about the splicing of the nearly 3000 introns of the Entamoeba genome have not been unraveled, particularly the splicing factors and their activities. Considering that many of such introns are located in metabolic genes, the knowledge of the splicing cues has the potential to be used to attack or control the parasite. We have found numerous new splicing-related factors which could have therapeutic benefit. We also detected all the DExH/A RNA helicases involved in splicing and splicing proofreading control. Still, Entamoeba is very inefficient in splicing fidelity, thus we may have found a possible model system to study these processes.
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Affiliation(s)
- Jesús Valdés
- Departament of Biochemistry, CINVESTAV, México D.F., Mexico.
| | - Tomoyoshi Nozaki
- Department of Parasitology, National Institute of Infectious Diseases, Tokyo, Japan
| | - Emi Sato
- Department of Parasitology, National Institute of Infectious Diseases, Tokyo, Japan
| | - Yoko Chiba
- University of Tsukuba, Graduate School of Life and Environmental Sciences, Tsukuba, Japan
| | - Kumiko Nakada-Tsukui
- Department of Parasitology, National Institute of Infectious Diseases, Tokyo, Japan
| | | | - Robert Winkler
- Department of Biotechnology and Biochemistry, CINVESTAV Unidad Irapuato, Irapuato, Guanajuato, Mexico
| | | | | | - Natsuki Watanabe
- University of Tsukuba, Graduate School of Life and Environmental Sciences, Tsukuba, Japan
| | - Herbert J Santos
- Department of Parasitology, National Institute of Infectious Diseases, Tokyo, Japan; University of Tsukuba, Graduate School of Life and Environmental Sciences, Tsukuba, Japan; Institute of Biology, College of Science, University of the Philippines Diliman, Quezon City, Philippines
| | - Yumiko Saito-Nakano
- Department of Parasitology, National Institute of Infectious Diseases, Tokyo, Japan
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Möhlmann S, Mathew R, Neumann P, Schmitt A, Lührmann R, Ficner R. Structural and functional analysis of the human spliceosomal DEAD-box helicase Prp28. ACTA CRYSTALLOGRAPHICA. SECTION D, BIOLOGICAL CRYSTALLOGRAPHY 2014; 70:1622-30. [PMID: 24914973 PMCID: PMC4051504 DOI: 10.1107/s1399004714006439] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/10/2014] [Accepted: 03/23/2014] [Indexed: 11/10/2022]
Abstract
The DEAD-box protein Prp28 is essential for pre-mRNA splicing as it plays a key role in the formation of an active spliceosome. Prp28 participates in the release of the U1 snRNP from the 5'-splice site during association of the U5·U4/U6 tri-snRNP, which is a crucial step in the transition from a pre-catalytic spliceosome to an activated spliceosome. Here, it is demonstrated that the purified helicase domain of human Prp28 (hPrp28ΔN) binds ADP, whereas binding of ATP and ATPase activity could not be detected. ATP binding could not be observed for purified full-length hPrp28 either, but within an assembled spliceosomal complex hPrp28 gains ATP-binding activity. In order to understand the structural basis for the ATP-binding deficiency of isolated hPrp28, the crystal structure of hPrp28ΔN was determined at 2.0 Å resolution. In the crystal the helicase domain adopts a wide-open conformation, as the two RecA-like domains are extraordinarily displaced from the productive ATPase conformation. Binding of ATP is hindered by a closed conformation of the P-loop, which occupies the space required for the γ-phosphate of ATP.
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Affiliation(s)
- Sina Möhlmann
- Molecular Structural Biology, Georg-August-University Göttingen, Justus-von-Liebig Weg 11, 37077 Göttingen, Germany
| | - Rebecca Mathew
- Cellular Biochemistry, Max-Planck-Institute for Biophysical Chemistry, Am Fassberg, 37077 Göttingen, Germany
| | - Piotr Neumann
- Molecular Structural Biology, Georg-August-University Göttingen, Justus-von-Liebig Weg 11, 37077 Göttingen, Germany
| | - Andreas Schmitt
- Molecular Structural Biology, Georg-August-University Göttingen, Justus-von-Liebig Weg 11, 37077 Göttingen, Germany
| | - Reinhard Lührmann
- Cellular Biochemistry, Max-Planck-Institute for Biophysical Chemistry, Am Fassberg, 37077 Göttingen, Germany
| | - Ralf Ficner
- Molecular Structural Biology, Georg-August-University Göttingen, Justus-von-Liebig Weg 11, 37077 Göttingen, Germany
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Hogg R, de Almeida RA, Ruckshanthi JPD, O'Keefe RT. Remodeling of U2-U6 snRNA helix I during pre-mRNA splicing by Prp16 and the NineTeen Complex protein Cwc2. Nucleic Acids Res 2014; 42:8008-23. [PMID: 24848011 PMCID: PMC4081067 DOI: 10.1093/nar/gku431] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Removal of intron regions from pre-messenger RNA (pre-mRNA) requires spliceosome assembly with pre-mRNA, then subsequent spliceosome remodeling to allow activation for the two steps of intron removal. Spliceosome remodeling is carried out through the action of DExD/H-box ATPases that modulate RNA-RNA and protein-RNA interactions. The ATPase Prp16 remodels the spliceosome between the first and second steps of splicing by catalyzing release of first step factors Yju2 and Cwc25 as well as destabilizing U2-U6 snRNA helix I. How Prp16 destabilizes U2-U6 helix I is not clear. We show that the NineTeen Complex (NTC) protein Cwc2 displays genetic interactions with the U6 ACAGAGA, the U6 internal stem loop (ISL) and the U2-U6 helix I, all RNA elements that form the spliceosome active site. We find that one function of Cwc2 is to stabilize U2-U6 snRNA helix I during splicing. Cwc2 also functionally cooperates with the NTC protein Isy1/NTC30. Mutation in Cwc2 can suppress the cold sensitive phenotype of the prp16-302 mutation indicating a functional link between Cwc2 and Prp16. Specifically the prp16-302 mutation in Prp16 stabilizes Cwc2 interactions with U6 snRNA and destabilizes Cwc2 interactions with pre-mRNA, indicating antagonistic functions of Cwc2 and Prp16. We propose that Cwc2 is a target for Prp16-mediated spliceosome remodeling during pre-mRNA splicing.
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Affiliation(s)
- Rebecca Hogg
- Faculty of Life Sciences, The University of Manchester, Oxford Road, Manchester, M13 9PT
| | | | | | - Raymond T O'Keefe
- Faculty of Life Sciences, The University of Manchester, Oxford Road, Manchester, M13 9PT
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Abstract
One of the most amazing findings in molecular biology was the discovery that eukaryotic genes are discontinuous, with coding DNA being interrupted by stretches of non-coding sequence. The subsequent realization that the intervening regions are removed from pre-mRNA transcripts via the activity of a common set of small nuclear RNAs (snRNAs), which assemble together with associated proteins into a complex known as the spliceosome, was equally surprising. How do cells coordinate the assembly of this molecular machine? And how does the spliceosome accurately recognize exons and introns to carry out the splicing reaction? Insights into these questions have been gained by studying the life cycle of spliceosomal snRNAs from their transcription, nuclear export and re-import to their dynamic assembly into the spliceosome. This assembly process can also affect the regulation of alternative splicing and has implications for human disease.
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Affiliation(s)
- A Gregory Matera
- Department of Biology, Department of Genetics and Integrative Program for Biological and Genome Sciences, Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina 27599, USA
| | - Zefeng Wang
- Department of Pharmacology, Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina 27599, USA
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Abstract
Superfamily 2 helicase proteins are ubiquitous in RNA biology and have an extraordinarily broad set of functional roles. Central among these roles are the promotion of rearrangements of structured RNAs and the remodeling of ribonucleoprotein complexes (RNPs), allowing formation of native RNA structure or progression through a functional cycle of structures. Although all superfamily 2 helicases share a conserved helicase core, they are divided evolutionarily into several families, and it is principally proteins from three families, the DEAD-box, DEAH/RHA, and Ski2-like families, that function to manipulate structured RNAs and RNPs. Strikingly, there are emerging differences in the mechanisms of these proteins, both between families and within the largest family (DEAD-box), and these differences appear to be tuned to their RNA or RNP substrates and their specific roles. This review outlines basic mechanistic features of the three families and surveys individual proteins and the current understanding of their biological substrates and mechanisms.
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Affiliation(s)
- Inga Jarmoskaite
- Department of Molecular Biosciences and the Institute for Cellular and Molecular Biology, University of Texas, Austin, Texas 78712; ,
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38
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Wlodaver AM, Staley JP. The DExD/H-box ATPase Prp2p destabilizes and proofreads the catalytic RNA core of the spliceosome. RNA (NEW YORK, N.Y.) 2014; 20:282-94. [PMID: 24442613 PMCID: PMC3923124 DOI: 10.1261/rna.042598.113] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2013] [Accepted: 10/30/2013] [Indexed: 05/25/2023]
Abstract
After undergoing massive RNA and protein rearrangements during assembly, the spliceosome undergoes a final, more subtle, ATP-dependent rearrangement that is essential for catalysis. This rearrangement requires the DEAH-box protein Prp2p, an RNA-dependent ATPase. Prp2p has been implicated in destabilizing interactions between the spliceosome and the protein complexes SF3 and RES, but a role for Prp2p in destabilizing RNA-RNA interactions has not been explored. Using directed molecular genetics in budding yeast, we have found that a cold-sensitive prp2 mutation is suppressed not only by mutations in SF3 and RES components but also by a range of mutations that disrupt the spliceosomal catalytic core element U2/U6 helix I, which is implicated in juxtaposing the 5' splice site and branch site and in positioning metal ions for catalysis within the context of a putative catalytic triplex; indeed, mutations in this putative catalytic triplex also suppressed a prp2 mutation. Remarkably, we also found that prp2 mutations rescue lethal mutations in U2/U6 helix I. These data provide evidence that RNA elements that comprise the catalytic core are already formed at the Prp2p stage and that Prp2p destabilizes these elements, directly or indirectly, both to proofread spliceosome activation and to promote reconfiguration of the spliceosome to a fully competent, catalytic conformation.
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Price AM, Görnemann J, Guthrie C, Brow DA. An unanticipated early function of DEAD-box ATPase Prp28 during commitment to splicing is modulated by U5 snRNP protein Prp8. RNA (NEW YORK, N.Y.) 2014; 20:46-60. [PMID: 24231520 PMCID: PMC3866644 DOI: 10.1261/rna.041970.113] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
The stepwise assembly of the highly dynamic spliceosome is guided by RNA-dependent ATPases of the DEAD-box family, whose regulation is poorly understood. In the canonical assembly model, the U4/U6.U5 triple snRNP binds only after joining of the U1 and, subsequently, U2 snRNPs to the intron-containing pre-mRNA. Catalytic activation requires the exchange of U6 for U1 snRNA at the 5' splice site, which is promoted by the DEAD-box protein Prp28. Because Prp8, an integral U5 snRNP protein, is thought to be a central regulator of DEAD-box proteins, we conducted a targeted search in Prp8 for cold-insensitive suppressors of a cold-sensitive Prp28 mutant, prp28-1. We identified a cluster of suppressor mutations in an N-terminal bromodomain-like sequence of Prp8. To identify the precise defect in prp28-1 strains that is suppressed by the Prp8 alleles, we analyzed spliceosome assembly in vivo and in vitro. Surprisingly, in the prp28-1 strain, we observed a block not only to spliceosome activation but also to one of the earliest steps of assembly, formation of the ATP-independent commitment complex 2 (CC2). The Prp8 suppressor partially corrected both the early assembly and later activation defects of prp28-1, supporting a role for this U5 snRNP protein in both the ATP-independent and ATP-dependent functions of Prp28. We conclude that the U5 snRNP has a role in the earliest events of assembly, prior to its stable incorporation into the spliceosome.
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Affiliation(s)
- Argenta M. Price
- Department of Biochemistry and Biophysics, University of California, San Francisco, California 94143, USA
| | - Janina Görnemann
- Department of Biomolecular Chemistry, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin 53706, USA
- Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany
| | - Christine Guthrie
- Department of Biochemistry and Biophysics, University of California, San Francisco, California 94143, USA
- Corresponding authorsE-mail E-mail
| | - David A. Brow
- Department of Biomolecular Chemistry, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin 53706, USA
- Corresponding authorsE-mail E-mail
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Zhang ZM, Yang F, Zhang J, Tang Q, Li J, Gu J, Zhou J, Xu YZ. Crystal structure of Prp5p reveals interdomain interactions that impact spliceosome assembly. Cell Rep 2013; 5:1269-78. [PMID: 24290758 DOI: 10.1016/j.celrep.2013.10.047] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2013] [Revised: 09/30/2013] [Accepted: 10/29/2013] [Indexed: 01/13/2023] Open
Abstract
The DEAD-box adenosine triphosphatase (ATPase) Prp5p facilitates U2 small nuclear ribonucleoprotein particle (snRNP) binding to the intron branch site region during spliceosome assembly. We present crystal structures of S. cerevisiae Prp5p alone and in complex with ADP at 2.12 Å and 1.95 Å resolution. The three-dimensional packing of Prp5p subdomains differs strikingly from that so far observed in other DEAD-box proteins: two RecA-like subdomains adopt an "open state" conformation stabilized by extensive interactions involving sequences that flank the two subdomains. This conformation is distinct from that required for ATP hydrolysis. Consistent with this, Prp5p mutations that destabilize interdomain interactions exhibited increased ATPase activity in vitro and inhibited splicing of suboptimal branch site substrates in vivo, whereas restoration of interdomain interactions reversed these effects. We conclude that the Prp5p open state conformation is biologically relevant and that disruption of the interdomain interaction facilitates a large-scale conformational change of Prp5p during U2 snRNP-branch site recognition.
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Affiliation(s)
- Zhi-Min Zhang
- State Key Laboratory of Bio-organic and Natural Products Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 200032, China
| | - Fei Yang
- Key Laboratory of Insect Developmental and Evolutionary Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China
| | - Jinru Zhang
- State Key Laboratory of Bio-organic and Natural Products Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 200032, China
| | - Qing Tang
- Key Laboratory of Insect Developmental and Evolutionary Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China
| | - Jie Li
- State Key Laboratory of Bio-organic and Natural Products Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 200032, China
| | - Jing Gu
- Key Laboratory of Insect Developmental and Evolutionary Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China
| | - Jiahai Zhou
- State Key Laboratory of Bio-organic and Natural Products Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 200032, China.
| | - Yong-Zhen Xu
- Key Laboratory of Insect Developmental and Evolutionary Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China.
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Christian H, Hofele RV, Urlaub H, Ficner R. Insights into the activation of the helicase Prp43 by biochemical studies and structural mass spectrometry. Nucleic Acids Res 2013; 42:1162-79. [PMID: 24165877 PMCID: PMC3902948 DOI: 10.1093/nar/gkt985] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Splicing of precursor messenger RNA is a hallmark of eukaryotic cells, which is carried out by the spliceosome, a multi-megadalton ribonucleoprotein machinery. The splicing reaction removes non-coding regions (introns) and ligates coding regions (exons). The spliceosome is a highly dynamic ribonucleoprotein complex that undergoes dramatic structural changes during its assembly, the catalysis and its disassembly. The transitions between the different steps during the splicing cycle are promoted by eight conserved DExD/H box ATPases. The DEAH-box protein Prp43 is responsible for the disassembly of the intron-lariat spliceosome and its helicase activity is activated by the G-patch protein Ntr1. Here, we investigate the activation of Prp43 by Ntr1 in the presence and absence of RNA substrate by functional assays and structural proteomics. Residues 51–110 of Ntr1 were identified to be the minimal fragment that induces full activation. We found protein–protein cross-links that indicate that Prp43 interacts with the G-patch motif of Ntr1 through its C-terminal domains. Additionally, we report on functionally important RNA binding residues in both proteins and propose a model for the activation of the helicase.
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Affiliation(s)
- Henning Christian
- Department for Molecular Structural Biology, Institute for Microbiology and Genetics, Georg-August-University Göttingen, D-37077 Göttingen, Germany, Bioanalytical Mass Spectrometry Group, Max-Planck-Institute of Biophysical Chemistry, D-37077 Göttingen, Germany and Bioanalytics, Department of Clinical Chemistry, University Medical Center Göttingen, D-37075 Göttingen, Germany
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42
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Koodathingal P, Staley JP. Splicing fidelity: DEAD/H-box ATPases as molecular clocks. RNA Biol 2013; 10:1073-9. [PMID: 23770752 PMCID: PMC3849154 DOI: 10.4161/rna.25245] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2013] [Revised: 05/29/2013] [Accepted: 06/01/2013] [Indexed: 12/28/2022] Open
Abstract
The spliceosome discriminates against suboptimal substrates, both during assembly and catalysis, thereby enhancing specificity during pre-mRNA splicing. Central to such fidelity mechanisms are a conserved subset of the DEAD- and DEAH-box ATPases, which belong to a superfamily of proteins that mediate RNP rearrangements in almost all RNA-dependent processes in the cell. Through an investigation of the mechanisms contributing to the specificity of 5' splice site cleavage, two related reports, one from our lab and the other from the Cheng lab, have provided insights into fidelity mechanisms utilized by the spliceosome. In our work, we found evidence for a kinetic proofreading mechanism in splicing in which the DEAH-box ATPase Prp16 discriminates against substrates undergoing slow 5' splice site cleavage. Additionally, our study revealed that discriminated substrates are discarded through a general spliceosome disassembly pathway, mediated by another DEAH-box ATPase Prp43. In their work, Tseng et al. described the underlying molecular events through which Prp16 discriminates against a splicing substrate during 5' splice site cleavage. Here, we present a synthesis of these two studies and, additionally, provide the first biochemical evidence for discrimination of a suboptimal splicing substrate just prior to 5' splice site cleavage. Together, these findings support a general mechanism for a ubiquitous superfamily of ATPases in enhancing specificity during RNA-dependent processes in the cell.
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Affiliation(s)
- Prakash Koodathingal
- Department of Molecular Genetics and Cell Biology; The University of Chicago; Chicago, IL USA
| | - Jonathan P. Staley
- Department of Molecular Genetics and Cell Biology; The University of Chicago; Chicago, IL USA
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