1
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Carrocci TJ, DeMario S, He K, Zeps NJ, Harkner CT, Chanfreau GF, Hoskins AA. Functional analysis of the zinc finger modules of the Saccharomyces cerevisiae splicing factor Luc7. RNA (NEW YORK, N.Y.) 2024; 30:1058-1069. [PMID: 38719745 PMCID: PMC11251517 DOI: 10.1261/rna.079956.124] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2024] [Accepted: 04/14/2024] [Indexed: 05/21/2024]
Abstract
Identification of splice sites is a critical step in pre-messenger RNA (pre-mRNA) splicing because the definition of the exon/intron boundaries controls what nucleotides are incorporated into mature mRNAs. The intron boundary with the upstream exon is initially identified through interactions with the U1 small nuclear ribonucleoprotein (snRNP). This involves both base-pairing between the U1 snRNA and the pre-mRNA as well as snRNP proteins interacting with the 5' splice site (5'ss)/snRNA duplex. In yeast, this duplex is buttressed by two conserved protein factors, Yhc1 and Luc7. Luc7 has three human paralogs (LUC7L, LUC7L2, and LUC7L3), which play roles in alternative splicing. What domains of these paralogs promote splicing at particular sites is not yet clear. Here, we humanized the zinc finger (ZnF) domains of the yeast Luc7 protein in order to understand their roles in splice site selection using reporter assays, transcriptome analysis, and genetic interactions. Although we were unable to determine a function for the first ZnF domain, humanization of the second ZnF domain to mirror that found in LUC7L or LUC7L2 resulted in altered usage of nonconsensus 5'ss. In contrast, the corresponding ZnF domain of LUC7L3 could not support yeast viability. Further, humanization of Luc7 can suppress mutation of the ATPase Prp28, which is involved in U1 release and exchange for U6 at the 5'ss. Our work reveals a role for the second ZnF of Luc7 in splice site selection and suggests that different ZnF domains may have different ATPase requirements for release by Prp28.
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Affiliation(s)
- Tucker J Carrocci
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - Samuel DeMario
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, California 90095, USA
| | - Kevin He
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, California 90095, USA
| | - Natalie J Zeps
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - Cade T Harkner
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - Guillaume F Chanfreau
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, California 90095, USA
- Molecular Biology Institute, University of California, Los Angeles, Los Angeles, California 90095, USA
| | - Aaron A Hoskins
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
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2
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Chalivendra S, Shi S, Li X, Kuang Z, Giovinazzo J, Zhang L, Rossi J, Wang J, Saviola AJ, Welty R, Liu S, Vaeth KF, Zhou ZH, Hansen KC, Taliaferro JM, Zhao R. Selected humanization of yeast U1 snRNP leads to global suppression of pre-mRNA splicing and mitochondrial dysfunction in the budding yeast. RNA (NEW YORK, N.Y.) 2024; 30:1070-1088. [PMID: 38688558 PMCID: PMC11251525 DOI: 10.1261/rna.079917.123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2023] [Accepted: 04/16/2024] [Indexed: 05/02/2024]
Abstract
The recognition of the 5' splice site (5' ss) is one of the earliest steps of pre-mRNA splicing. To better understand, the mechanism and regulation of 5' ss recognition, we selectively humanized components of the yeast U1 (yU1) snRNP to reveal the function of these components in 5' ss recognition and splicing. We targeted U1C and Luc7, two proteins that interact with and stabilize the yU1 snRNA and the 5' ss RNA duplex. We replaced the zinc-finger (ZnF) domain of yeast U1C (yU1C) with its human counterpart, which resulted in a cold-sensitive growth phenotype and moderate splicing defects. We next added an auxin-inducible degron to yeast Luc7 (yLuc7) protein (to mimic the lack of Luc7Ls in human U1 snRNP). We found that Luc7-depleted yU1 snRNP resulted in the concomitant loss of Prp40 and Snu71 (two other essential yU1 snRNP proteins), and further biochemical analyses suggest a model of how these three proteins interact with each other in the U1 snRNP. The loss of these proteins resulted in a significant growth retardation accompanied by a global suppression of pre-mRNA splicing. The splicing suppression led to mitochondrial dysfunction as revealed by a release of Fe2+ into the growth medium and an induction of mitochondrial reactive oxygen species. Together, these observations indicate that the human U1C ZnF can substitute that of yeast, Luc7 is essential for the incorporation of the Luc7-Prp40-Snu71 trimer into yU1 snRNP, and splicing plays a major role in the regulation of mitochondrial function in yeast.
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Affiliation(s)
- Subbaiah Chalivendra
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, Colorado 80045, USA
| | - Shasha Shi
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, Colorado 80045, USA
| | - Xueni Li
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, Colorado 80045, USA
| | - Zhiling Kuang
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, Colorado 80045, USA
| | - Joseph Giovinazzo
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, Colorado 80045, USA
| | - Lingdi Zhang
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, Colorado 80045, USA
| | - John Rossi
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, Colorado 80045, USA
| | - Jingxin Wang
- Department of Medicinal Chemistry, University of Kansas, Lawrence, Kansas 66047, USA
| | - Anthony J Saviola
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, Colorado 80045, USA
| | - Robb Welty
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, Colorado 80045, USA
| | - Shiheng Liu
- Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles, California 90095, USA
| | - Katherine F Vaeth
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, Colorado 80045, USA
| | - Z Hong Zhou
- Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles, California 90095, USA
| | - Kirk C Hansen
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, Colorado 80045, USA
| | - J Matthew Taliaferro
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, Colorado 80045, USA
| | - Rui Zhao
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, Colorado 80045, USA
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3
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Senn KA, Hoskins AA. Mechanisms and regulation of spliceosome-mediated pre-mRNA splicing in Saccharomyces cerevisiae. WILEY INTERDISCIPLINARY REVIEWS. RNA 2024; 15:e1866. [PMID: 38972853 DOI: 10.1002/wrna.1866] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2024] [Revised: 05/19/2024] [Accepted: 05/28/2024] [Indexed: 07/09/2024]
Abstract
Pre-mRNA splicing, the removal of introns and ligation of flanking exons, is a crucial step in eukaryotic gene expression. The spliceosome, a macromolecular complex made up of five small nuclear RNAs (snRNAs) and dozens of proteins, assembles on introns via a complex pathway before catalyzing the two transesterification reactions necessary for splicing. All of these steps have the potential to be highly regulated to ensure correct mRNA isoform production for proper cellular function. While Saccharomyces cerevisiae (yeast) has a limited set of intron-containing genes, many of these genes are highly expressed, resulting in a large number of transcripts in a cell being spliced. As a result, splicing regulation is of critical importance for yeast. Just as in humans, yeast splicing can be influenced by protein components of the splicing machinery, structures and properties of the pre-mRNA itself, or by the action of trans-acting factors. It is likely that further analysis of the mechanisms and pathways of splicing regulation in yeast can reveal general principles applicable to other eukaryotes. This article is categorized under: RNA Processing > Splicing Mechanisms RNA Processing > Splicing Regulation/Alternative Splicing.
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Affiliation(s)
- Katherine Anne Senn
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Aaron A Hoskins
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin, USA
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin, USA
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4
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Yang WQ, Ge JY, Zhang X, Zhu WY, Lin L, Shi Y, Xu B, Liu RJ. THUMPD2 catalyzes the N2-methylation of U6 snRNA of the spliceosome catalytic center and regulates pre-mRNA splicing and retinal degeneration. Nucleic Acids Res 2024; 52:3291-3309. [PMID: 38165050 PMCID: PMC11014329 DOI: 10.1093/nar/gkad1243] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2023] [Revised: 12/13/2023] [Accepted: 12/21/2023] [Indexed: 01/03/2024] Open
Abstract
The mechanisms by which the relatively conserved spliceosome manages the enormously large number of splicing events that occur in humans (∼200 000 versus ∼300 in yeast) are poorly understood. Here, we show deposition of one RNA modification-N2-methylguanosine (m2G) on the G72 of U6 snRNA (the catalytic center of the spliceosome) promotes efficient pre-mRNA splicing activity in human cells. This modification was identified to be conserved among vertebrates. Further, THUMPD2 was demonstrated as the methyltransferase responsible for U6 m2G72 by explicitly recognizing the U6-specific sequences and structural elements. The knock-out of THUMPD2 eliminated U6 m2G72 and impaired the pre-mRNA splicing activity, resulting in thousands of changed alternative splicing events of endogenous pre-mRNAs in human cells. Notably, the aberrantly spliced pre-mRNA population elicited the nonsense-mediated mRNA decay pathway. We further show that THUMPD2 was associated with age-related macular degeneration and retinal function. Our study thus demonstrates how an RNA epigenetic modification of the major spliceosome regulates global pre-mRNA splicing and impacts physiology and disease.
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Affiliation(s)
- Wen-Qing Yang
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Jian-Yang Ge
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Xiaofeng Zhang
- Division of Reproduction and Genetics, The First Affiliated Hospital of USTC, MOE Key Laboratory for Membraneless Organelles and Cellular Dynamics, Hefei National Research Center for Interdisciplinary Sciences at the Microscale, Biomedical Sciences and Health Laboratory of Anhui Province, Division of Life Sciences and Medicine, University of Science and Technology of China, 230027 Hefei, China
| | - Wen-Yu Zhu
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Lin Lin
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Yigong Shi
- Institute of Biology, Westlake Institute for Advanced Study, Westlake University, Hangzhou 310064,Zhejiang Province, China
| | - Beisi Xu
- Center for Applied Bioinformatics, St. Jude Children's Research Hospital, Memphis, TN, USA
| | - Ru-Juan Liu
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
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5
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Carrocci TJ, DeMario S, He K, Zeps NJ, Harkner CT, Chanfreau G, Hoskins AA. Functional Analysis of the Zinc Finger Modules of the S. cerevisiae Splicing Factor Luc7. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.04.578419. [PMID: 38352541 PMCID: PMC10862913 DOI: 10.1101/2024.02.04.578419] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/19/2024]
Abstract
Identification of splice sites is a critical step in pre-mRNA splicing since definition of the exon/intron boundaries controls what nucleotides are incorporated into mature mRNAs. The intron boundary with the upstream exon is initially identified through interactions with the U1 snRNP. This involves both base pairing between the U1 snRNA and the pre-mRNA as well as snRNP proteins interacting with the 5' splice site/snRNA duplex. In yeast, this duplex is buttressed by two conserved protein factors, Yhc1 and Luc7. Luc7 has three human paralogs (LUC7L, LUC7L2, and LUC7L3) which play roles in alternative splicing. What domains of these paralogs promote splicing at particular sites is not yet clear. Here, we humanized the zinc finger domains of the yeast Luc7 protein in order to understand their roles in splice site selection using reporter assays, transcriptome analysis, and genetic interactions. While we were unable to determine a function for the first zinc finger domain, humanization of the second zinc finger domain to mirror that found in LUC7L or LUC7L2 resulted in altered usage of nonconsensus 5' splice sites. In contrast, the corresponding zinc finger domain of LUC7L3 could not support yeast viability. Further, humanization of Luc7 can suppress mutation of the ATPase Prp28, which is involved in U1 release and exchange for U6 at the 5' splice site. Our work reveals a role for the second zinc finger of Luc7 in splice site selection and suggests that different zinc finger domains may have different ATPase requirements for release by Prp28.
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Affiliation(s)
- Tucker J. Carrocci
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Samuel DeMario
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095, USA
- Molecular Biology Institute, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Kevin He
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095, USA
- Molecular Biology Institute, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Natalie J. Zeps
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Cade T. Harkner
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Guillaume Chanfreau
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095, USA
- Molecular Biology Institute, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Aaron A. Hoskins
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
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6
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Hunter O, Talkish J, Quick-Cleveland J, Igel H, Tan A, Kuersten S, Katzman S, Donohue JP, S Jurica M, Ares M. Broad variation in response of individual introns to splicing inhibitors in a humanized yeast strain. RNA (NEW YORK, N.Y.) 2024; 30:149-170. [PMID: 38071476 PMCID: PMC10798247 DOI: 10.1261/rna.079866.123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2023] [Accepted: 11/14/2023] [Indexed: 12/19/2023]
Abstract
Intron branchpoint (BP) recognition by the U2 snRNP is a critical step of splicing, vulnerable to recurrent cancer mutations and bacterial natural product inhibitors. The BP binds a conserved pocket in the SF3B1 (human) or Hsh155 (yeast) U2 snRNP protein. Amino acids that line this pocket affect the binding of splicing inhibitors like Pladienolide-B (Plad-B), such that organisms differ in their sensitivity. To study the mechanism of splicing inhibitor action in a simplified system, we modified the naturally Plad-B resistant yeast Saccharomyces cerevisiae by changing 14 amino acids in the Hsh155 BP pocket to those from human. This humanized yeast grows normally, and splicing is largely unaffected by the mutation. Splicing is inhibited within minutes after the addition of Plad-B, and different introns appear inhibited to different extents. Intron-specific inhibition differences are also observed during cotranscriptional splicing in Plad-B using single-molecule intron tracking to minimize gene-specific transcription and decay rates that cloud estimates of inhibition by standard RNA-seq. Comparison of Plad-B intron sensitivities to those of the structurally distinct inhibitor Thailanstatin-A reveals intron-specific differences in sensitivity to different compounds. This work exposes a complex relationship between the binding of different members of this class of inhibitors to the spliceosome and intron-specific rates of BP recognition and catalysis. Introns with variant BP sequences seem particularly sensitive, echoing observations from mammalian cells, where monitoring individual introns is complicated by multi-intron gene architecture and alternative splicing. The compact yeast system may hasten the characterization of splicing inhibitors, accelerating improvements in selectivity and therapeutic efficacy.
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Affiliation(s)
- Oarteze Hunter
- Center for Molecular Biology of RNA, University of California, Santa Cruz, California 95064, USA
| | - Jason Talkish
- Center for Molecular Biology of RNA, University of California, Santa Cruz, California 95064, USA
| | - Jen Quick-Cleveland
- Center for Molecular Biology of RNA, University of California, Santa Cruz, California 95064, USA
| | - Haller Igel
- Center for Molecular Biology of RNA, University of California, Santa Cruz, California 95064, USA
| | - Asako Tan
- Illumina, Inc., Madison, Wisconsin 53719, USA
| | | | - Sol Katzman
- Center for Molecular Biology of RNA, University of California, Santa Cruz, California 95064, USA
| | - John Paul Donohue
- Center for Molecular Biology of RNA, University of California, Santa Cruz, California 95064, USA
| | - Melissa S Jurica
- Center for Molecular Biology of RNA, University of California, Santa Cruz, California 95064, USA
| | - Manuel Ares
- Center for Molecular Biology of RNA, University of California, Santa Cruz, California 95064, USA
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7
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Perchlik M, Sasse A, Mostafavi S, Fields S, Cuperus JT. Impact on splicing in Saccharomyces cerevisiae of random 50-base sequences inserted into an intron. RNA (NEW YORK, N.Y.) 2023; 30:52-67. [PMID: 37879864 PMCID: PMC10726166 DOI: 10.1261/rna.079752.123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2023] [Accepted: 10/18/2023] [Indexed: 10/27/2023]
Abstract
Intron splicing is a key regulatory step in gene expression in eukaryotes. Three sequence elements required for splicing-5' and 3' splice sites and a branchpoint-are especially well-characterized in Saccharomyces cerevisiae, but our understanding of additional intron features that impact splicing in this organism is incomplete, due largely to its small number of introns. To overcome this limitation, we constructed a library in S. cerevisiae of random 50-nt (N50) elements individually inserted into the intron of a reporter gene and quantified canonical splicing and the use of cryptic splice sites by sequencing analysis. More than 70% of approximately 140,000 N50 elements reduced splicing by at least 20%. N50 features, including higher GC content, presence of GU repeats, and stronger predicted secondary structure of its pre-mRNA, correlated with reduced splicing efficiency. A likely basis for the reduced splicing of such a large proportion of variants is the formation of RNA structures that pair N50 bases-such as the GU repeats-with other bases specifically within the reporter pre-mRNA analyzed. However, multiple models were unable to explain more than a small fraction of the variance in splicing efficiency across the library, suggesting that complex nonlinear interactions in RNA structures are not accurately captured by RNA structure prediction methods. Our results imply that the specific context of a pre-mRNA may determine the bases allowable in an intron to prevent secondary structures that reduce splicing. This large data set can serve as a resource for further exploration of splicing mechanisms.
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Affiliation(s)
- Molly Perchlik
- Department of Genome Sciences, University of Washington, Seattle, Washington 98195, USA
| | - Alexander Sasse
- Paul G. Allen School of Computer Science and Engineering, University of Washington, Seattle, Washington 98195, USA
| | - Sara Mostafavi
- Paul G. Allen School of Computer Science and Engineering, University of Washington, Seattle, Washington 98195, USA
| | - Stanley Fields
- Department of Genome Sciences, University of Washington, Seattle, Washington 98195, USA
- Department of Medicine, University of Washington, Seattle, Washington 98195, USA
| | - Josh T Cuperus
- Department of Genome Sciences, University of Washington, Seattle, Washington 98195, USA
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8
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Chalivendra S, Shi S, Li X, Kuang Z, Giovinazzo J, Zhang L, Rossi J, Saviola AJ, Wang J, Welty R, Liu S, Vaeth K, Zhou ZH, Hansen KC, Taliaferro JM, Zhao R. Selected humanization of yeast U1 snRNP leads to global suppression of pre-mRNA splicing and mitochondrial dysfunction in the budding yeast. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.15.571893. [PMID: 38168357 PMCID: PMC10760170 DOI: 10.1101/2023.12.15.571893] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2024]
Abstract
The recognition of 5' splice site (5' ss) is one of the earliest steps of pre-mRNA splicing. To better understand the mechanism and regulation of 5' ss recognition, we selectively humanized components of the yeast U1 snRNP to reveal the function of these components in 5' ss recognition and splicing. We targeted U1C and Luc7, two proteins that interact with and stabilize the yeast U1 (yU1) snRNA and the 5' ss RNA duplex. We replaced the Zinc-Finger (ZnF) domain of yU1C with its human counterpart, which resulted in cold-sensitive growth phenotype and moderate splicing defects. Next, we added an auxin-inducible degron to yLuc7 protein and found that Luc7-depleted yU1 snRNP resulted in the concomitant loss of PRP40 and Snu71 (two other essential yeast U1 snRNP proteins), and further biochemical analyses suggest a model of how these three proteins interact with each other in the U1 snRNP. The loss of these proteins resulted in a significant growth retardation accompanied by a global suppression of pre-mRNA splicing. The splicing suppression led to mitochondrial dysfunction as revealed by a release of Fe 2+ into the growth medium and an induction of mitochondrial reactive oxygen species. Together, these observations indicate that the human U1C ZnF can substitute that of yeast, Luc7 is essential for the incorporation of the Luc7-Prp40-Snu71 trimer into yeast U1 snRNP, and splicing plays a major role in the regulation of mitochondria function in yeast.
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9
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Hunter O, Talkish J, Quick-Cleveland J, Igel H, Tan A, Kuersten S, Katzman S, Donohue JP, Jurica M, Ares M. Broad variation in response of individual introns to splicing inhibitors in a humanized yeast strain. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.05.560965. [PMID: 37873484 PMCID: PMC10592967 DOI: 10.1101/2023.10.05.560965] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2023]
Abstract
Intron branch point (BP) recognition by the U2 snRNP is a critical step of splicing, vulnerable to recurrent cancer mutations and bacterial natural product inhibitors. The BP binds a conserved pocket in the SF3B1 (human) or Hsh155 (yeast) U2 snRNP protein. Amino acids that line this pocket affect binding of splicing inhibitors like Pladienolide-B (Plad-B), such that organisms differ in their sensitivity. To study the mechanism of splicing inhibitor action in a simplified system, we modified the naturally Plad-B resistant yeast Saccharomyces cerevisiae by changing 14 amino acids in the Hsh155 BP pocket to those from human. This humanized yeast grows normally, and splicing is largely unaffected by the mutation. Splicing is inhibited within minutes after addition of Plad-B, and different introns appear inhibited to different extents. Intron-specific inhibition differences are also observed during co-transcriptional splicing in Plad-B using single-molecule intron tracking (SMIT) to minimize gene-specific transcription and decay rates that cloud estimates of inhibition by standard RNA-seq. Comparison of Plad-B intron sensitivities to those of the structurally distinct inhibitor Thailanstatin-A reveals intron-specific differences in sensitivity to different compounds. This work exposes a complex relationship between binding of different members of this class of inhibitors to the spliceosome and intron-specific rates of BP recognition and catalysis. Introns with variant BP sequences seem particularly sensitive, echoing observations from mammalian cells, where monitoring individual introns is complicated by multi-intron gene architecture and alternative splicing. The compact yeast system may hasten characterization of splicing inhibitors, accelerating improvements in selectivity and therapeutic efficacy.
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Affiliation(s)
- Oarteze Hunter
- Center for Molecular Biology of RNA, University of California, Santa Cruz, CA 95064
| | - Jason Talkish
- Center for Molecular Biology of RNA, University of California, Santa Cruz, CA 95064
| | - Jen Quick-Cleveland
- Center for Molecular Biology of RNA, University of California, Santa Cruz, CA 95064
| | - Haller Igel
- Center for Molecular Biology of RNA, University of California, Santa Cruz, CA 95064
| | | | | | - Sol Katzman
- Center for Molecular Biology of RNA, University of California, Santa Cruz, CA 95064
| | - John Paul Donohue
- Center for Molecular Biology of RNA, University of California, Santa Cruz, CA 95064
| | - Melissa Jurica
- Center for Molecular Biology of RNA, University of California, Santa Cruz, CA 95064
| | - Manuel Ares
- Center for Molecular Biology of RNA, University of California, Santa Cruz, CA 95064
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10
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Pino MG, Rich KA, Hall NJ, Jones ML, Fox A, Musier-Forsyth K, Kolb SJ. Heterogeneous splicing patterns resulting from KIF5A variants associated with amyotrophic lateral sclerosis. Hum Mol Genet 2023; 32:3166-3180. [PMID: 37593923 DOI: 10.1093/hmg/ddad134] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Revised: 07/28/2023] [Accepted: 08/03/2023] [Indexed: 08/19/2023] Open
Abstract
Single-nucleotide variants (SNVs) in the gene encoding Kinesin Family Member 5A (KIF5A), a neuronal motor protein involved in anterograde transport along microtubules, have been associated with amyotrophic lateral sclerosis (ALS). ALS is a rapidly progressive and fatal neurodegenerative disease that primarily affects the motor neurons. Numerous ALS-associated KIF5A SNVs are clustered near the splice-site junctions of the penultimate exon 27 and are predicted to alter the carboxy-terminal (C-term) cargo-binding domain of KIF5A. Mis-splicing of exon 27, resulting in exon exclusion, is proposed to be the mechanism by which these SNVs cause ALS. Whether all SNVs proximal to exon 27 result in exon exclusion is unclear. To address this question, we designed an in vitro minigene splicing assay in human embryonic kidney 293 cells, which revealed heterogeneous site-specific effects on splicing: only 5' splice-site (5'ss) SNVs resulted in exon skipping. We also quantified splicing in select clustered, regularly interspaced, short palindromic repeats-edited human stem cells, differentiated to motor neurons, and in neuronal tissues from a 5'ss SNV knock-in mouse, which showed the same result. Moreover, the survival of representative 3' splice site, 5'ss, and truncated C-term variant KIF5A (v-KIF5A) motor neurons was severely reduced compared with wild-type motor neurons, and overt morphological changes were apparent. While the total KIF5A mRNA levels were comparable across the cell lines, the total KIF5A protein levels were decreased for v-KIF5A lines, suggesting an impairment of protein synthesis or stability. Thus, despite the heterogeneous effect on ribonucleic acid splicing, KIF5A SNVs similarly reduce the availability of the KIF5A protein, leading to axonal transport defects and motor neuron pathology.
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Affiliation(s)
- Megan G Pino
- Department of Neurology, The Ohio State University Wexner Medical Center, Columbus, OH 43210, United States
- Center for RNA Biology, The Ohio State University, Columbus, OH 43210, United States
- Department of Biological Chemistry & Pharmacology, The Ohio State University Wexner Medical Center, Columbus, OH 43210, United States
| | - Kelly A Rich
- Department of Neurology, The Ohio State University Wexner Medical Center, Columbus, OH 43210, United States
| | - Nicholas J Hall
- Department of Neurology, The Ohio State University Wexner Medical Center, Columbus, OH 43210, United States
- Center for RNA Biology, The Ohio State University, Columbus, OH 43210, United States
| | - Meredith L Jones
- Department of Neurology, The Ohio State University Wexner Medical Center, Columbus, OH 43210, United States
| | - Ashley Fox
- Department of Neurology, The Ohio State University Wexner Medical Center, Columbus, OH 43210, United States
| | - Karin Musier-Forsyth
- Center for RNA Biology, The Ohio State University, Columbus, OH 43210, United States
- Department of Chemistry & Biochemistry, The Ohio State University Wexner Medical Center, Columbus, OH 43210, United States
| | - Stephen J Kolb
- Department of Neurology, The Ohio State University Wexner Medical Center, Columbus, OH 43210, United States
- Center for RNA Biology, The Ohio State University, Columbus, OH 43210, United States
- Department of Biological Chemistry & Pharmacology, The Ohio State University Wexner Medical Center, Columbus, OH 43210, United States
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11
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Myburgh MW, Schwerdtfeger KS, Cripwell RA, van Zyl WH, Viljoen-Bloom M. Promoters and introns as key drivers for enhanced gene expression in Saccharomyces cerevisiae. ADVANCES IN APPLIED MICROBIOLOGY 2023; 124:1-29. [PMID: 37597945 DOI: 10.1016/bs.aambs.2023.07.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/21/2023]
Abstract
The transcription of genes in the yeast Saccharomyces cerevisiae is governed by multiple layers of regulatory elements and proteins, cooperating to ensure optimum expression of the final protein product based on the cellular requirements. Promoters have always been regarded as the most important determinant of gene transcription, but introns also play a key role in the expression of intron-encoding genes. Some introns can enhance transcription when introduced either promoter-proximal or embedded in the open reading frame of genes. However, the outcome is seldom predictable, with some introns increasing or decreasing transcription depending on the promoter and reporter gene employed. This chapter provides an overview of the general structure and function of promoters and introns and how they may cooperate during transcription to allow intron-mediated enhancement of gene expression. Since S. cerevisiae is a suitable host for recombinant protein production on a commercial level, stronger and more controllable promoters are in high demand. Enhanced gene expression can be achieved via promoter engineering, which may include introns that increase the efficacy of recombinant expression cassettes. Different models for the role of introns in transcription are briefly discussed to show how these intervening sequences can actively interact with the transcription machinery. Furthermore, recent examples of improved protein production via the introduction of promoter-proximal introns are highlighted to showcase the potential value of intron-mediated enhancement of gene expression.
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Affiliation(s)
| | | | - Rosemary Anne Cripwell
- Department of Microbiology, Stellenbosch University, Private Bag X1, Matieland, South Africa
| | - Willem Heber van Zyl
- Department of Microbiology, Stellenbosch University, Private Bag X1, Matieland, South Africa
| | - Marinda Viljoen-Bloom
- Department of Microbiology, Stellenbosch University, Private Bag X1, Matieland, South Africa.
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12
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Wong DK, Grisdale CJ, Slat VA, Rader SD, Fast NM. The evolution of pre-mRNA splicing and its machinery revealed by reduced extremophilic red algae. J Eukaryot Microbiol 2023; 70:e12927. [PMID: 35662328 DOI: 10.1111/jeu.12927] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
The Cyanidiales are a group of mostly thermophilic and acidophilic red algae that thrive near volcanic vents. Despite their phylogenetic relationship, the reduced genomes of Cyanidioschyzon merolae and Galdieria sulphuraria are strikingly different with respect to pre-mRNA splicing, a ubiquitous eukaryotic feature. Introns are rare and spliceosomal machinery is extremely reduced in C. merolae, in contrast to G. sulphuraria. Previous studies also revealed divergent spliceosomes in the mesophilic red alga Porphyridium purpureum and the red algal derived plastid of Guillardia theta (Cryptophyta), along with unusually high levels of unspliced transcripts. To further examine the evolution of splicing in red algae, we compared C. merolae and G. sulphuraria, investigating splicing levels, intron position, intron sequence features, and the composition of the spliceosome. In addition to identifying 11 additional introns in C. merolae, our transcriptomic analysis also revealed typical eukaryotic splicing in G. sulphuraria, whereas most transcripts in C. merolae remain unspliced. The distribution of intron positions within their host genes was examined to provide insight into patterns of intron loss in red algae. We observed increasing variability of 5' splice sites and branch donor regions with increasing intron richness. We also found these relationships to be connected to reductions in and losses of corresponding parts of the spliceosome. Our findings highlight patterns of intron and spliceosome evolution in related red algae under the pressures of genome reduction.
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Affiliation(s)
- Donald K Wong
- Biodiversity Research Centre and Department of Botany, University of British Columbia, Vancouver, BC, Canada
| | - Cameron J Grisdale
- Biodiversity Research Centre and Department of Botany, University of British Columbia, Vancouver, BC, Canada.,Michael Smith Genome Sciences Centre, Vancouver, BC, Canada
| | - Viktor A Slat
- Department of Chemistry, University of Northern British Columbia, Prince George, BC, Canada
| | - Stephen D Rader
- Department of Chemistry, University of Northern British Columbia, Prince George, BC, Canada
| | - Naomi M Fast
- Biodiversity Research Centre and Department of Botany, University of British Columbia, Vancouver, BC, Canada
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13
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Gabrielli F, Antinucci M, Tofanelli S. Gene Structure Evolution of the Short-Chain Dehydrogenase/Reductase (SDR) Family. Genes (Basel) 2022; 14:110. [PMID: 36672851 PMCID: PMC9859523 DOI: 10.3390/genes14010110] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2022] [Revised: 12/12/2022] [Accepted: 12/22/2022] [Indexed: 12/31/2022] Open
Abstract
SDR (Short-chain Dehydrogenases/Reductases) are one of the oldest and heterogeneous superfamily of proteins, whose classification is problematic because of the low percent identity, even within families. To get clearer insights into SDR molecular evolution, we explored the splicing site organization of the 75 human SDR genes across their vertebrate and invertebrate orthologs. We found anomalous gene structures in members of the human SDR7C and SDR42E families that provide clues of retrogene properties and independent evolutionary trajectories from a common invertebrate ancestor. The same analyses revealed that the identity value between human and invertebrate non-allelic variants is not necessarily associated with the homologous gene structure. Accordingly, a revision of the SDR nomenclature is proposed by including the human SDR40C1 and SDR7C gene in the same family.
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Affiliation(s)
- Franco Gabrielli
- Department of Biology, University of Pisa, Via Ghini, 13-56126 Pisa, Italy
| | - Marco Antinucci
- Department of Medicine and Life Sciences, Institute of Evolutionary Biology (UPF-CSIC), Universitat Pompeu Fabra, 08002 Barcelona, Spain
| | - Sergio Tofanelli
- Department of Biology, University of Pisa, Via Ghini, 13-56126 Pisa, Italy
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14
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González-Rodríguez P, Delorme-Axford E, Bernard A, Keane L, Stratoulias V, Grabert K, Engskog-Vlachos P, Füllgrabe J, Klionsky DJ, Joseph B. SETD2 transcriptional control of ATG14L/S isoforms regulates autophagosome-lysosome fusion. Cell Death Dis 2022; 13:953. [PMID: 36371383 PMCID: PMC9653477 DOI: 10.1038/s41419-022-05381-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2022] [Revised: 10/19/2022] [Accepted: 10/26/2022] [Indexed: 11/13/2022]
Abstract
Macroautophagy/autophagy is an evolutionarily conserved and tightly regulated catabolic process involved in the maintenance of cellular homeostasis whose dysregulation is implicated in several pathological processes. Autophagy begins with the formation of phagophores that engulf cytoplasmic cargo and mature into double-membrane autophagosomes; the latter fuse with lysosomes/vacuoles for cargo degradation and recycling. Here, we report that yeast Set2, a histone lysine methyltransferase, and its mammalian homolog, SETD2, both act as positive transcriptional regulators of autophagy. However, whereas Set2 regulates the expression of several autophagy-related (Atg) genes upon nitrogen starvation, SETD2 effects in mammals were found to be more restricted. In fact, SETD2 appears to primarily regulate the differential expression of protein isoforms encoded by the ATG14 gene. SETD2 promotes the expression of a long ATG14 isoform, ATG14L, that contains an N-terminal cysteine repeats domain, essential for the efficient fusion of the autophagosome with the lysosome, that is absent in the short ATG14 isoform, ATG14S. Accordingly, SETD2 loss of function decreases autophagic flux, as well as the turnover of aggregation-prone proteins such as mutant HTT (huntingtin) leading to increased cellular toxicity. Hence, our findings bring evidence to the emerging concept that the production of autophagy-related protein isoforms can differentially affect core autophagy machinery bringing an additional level of complexity to the regulation of this biological process in more complex organisms.
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Affiliation(s)
- Patricia González-Rodríguez
- Institute of Environmental Medicine, Toxicology Unit, Karolinska Institutet, 17177, Stockholm, Sweden
- Department of Oncology Pathology, Cancer Centrum Karolinska, Karolinska Institutet, 171 76, Stockholm, Sweden
- Division of Biochemistry, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
| | - Elizabeth Delorme-Axford
- Life Sciences Institute, and the Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
- Department of Biological Sciences, Oakland University, Rochester, MI, USA
| | - Amélie Bernard
- Life Sciences Institute, and the Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
- University of Bordeaux, CNRS, Laboratoire de Biogenèse Membranaire, UMR 5200, F-33140, Villenave d'Ornon, France
| | - Lily Keane
- Institute of Environmental Medicine, Toxicology Unit, Karolinska Institutet, 17177, Stockholm, Sweden
| | - Vassilis Stratoulias
- Institute of Environmental Medicine, Toxicology Unit, Karolinska Institutet, 17177, Stockholm, Sweden
- Department of Oncology Pathology, Cancer Centrum Karolinska, Karolinska Institutet, 171 76, Stockholm, Sweden
- Neuroscience Center, HiLIFE, University of Helsinki, Helsinki, Finland
| | - Kathleen Grabert
- Institute of Environmental Medicine, Toxicology Unit, Karolinska Institutet, 17177, Stockholm, Sweden
| | - Pinelopi Engskog-Vlachos
- Institute of Environmental Medicine, Toxicology Unit, Karolinska Institutet, 17177, Stockholm, Sweden
| | - Jens Füllgrabe
- Department of Oncology Pathology, Cancer Centrum Karolinska, Karolinska Institutet, 171 76, Stockholm, Sweden
| | - Daniel J Klionsky
- Life Sciences Institute, and the Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
| | - Bertrand Joseph
- Institute of Environmental Medicine, Toxicology Unit, Karolinska Institutet, 17177, Stockholm, Sweden.
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15
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Gildea MA, Dwyer ZW, Pleiss JA. Transcript-specific determinants of pre-mRNA splicing revealed through in vivo kinetic analyses of the 1 st and 2 nd chemical steps. Mol Cell 2022; 82:2967-2981.e6. [PMID: 35830855 PMCID: PMC9391291 DOI: 10.1016/j.molcel.2022.06.020] [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: 10/13/2020] [Revised: 01/31/2022] [Accepted: 06/12/2022] [Indexed: 10/17/2022]
Abstract
We generate high-precision measurements of the in vivo rates of both chemical steps of pre-mRNA splicing across the genome-wide complement of substrates in yeast by coupling metabolic labeling, multiplexed primer-extension sequencing, and kinetic modeling. We demonstrate that the rates of intron removal vary widely, splice-site sequences are primary determinants of 1st step but have little apparent impact on 2nd step rates, and the 2nd step is generally faster than the 1st step. Ribosomal protein genes (RPGs) are spliced faster than non-RPGs at each step, and RPGs share evolutionarily conserved properties that may contribute to their faster splicing. A genetic variant defective in the 1st step of the pathway reveals a genome-wide defect in the 1st step but an unexpected, transcript-specific change in the 2nd step. Our work demonstrates that extended co-transcriptional association is an important determinant of splicing rate, a conclusion at odds with recent claims of ultra-fast splicing.
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Affiliation(s)
- Michael A Gildea
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14850, USA
| | - Zachary W Dwyer
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14850, USA
| | - Jeffrey A Pleiss
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14850, USA.
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16
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Kikuta H, Goto S, Kondo M, Akada R, Hoshida H. Identification of essential intron sequences that enhance gene expression independently of splicing in the yeast Saccharomyces cerevisiae. BIOCHIMICA ET BIOPHYSICA ACTA. GENE REGULATORY MECHANISMS 2022; 1865:194784. [PMID: 34990853 DOI: 10.1016/j.bbagrm.2021.194784] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Revised: 12/12/2021] [Accepted: 12/15/2021] [Indexed: 06/14/2023]
Abstract
Gene expression in eukaryotes is enhanced by the presence of introns in a process known as intron-mediated enhancement (IME), but its mechanism remains unclear. In Saccharomyces cerevisiae, sequences at the 5'-splice sites (SS) and branch point sites (BPS) are highly conserved compared with other higher eukaryotes. Here, the minimum intron sequence essential for IME was investigated using various short introns and a yeast codon-optimized luciferase gene as an IME model. Mutations at the 5'-SS conserved sequence and branch point in the QCR10 intron caused splicing deficiency with either a complete loss or a marked decrease in IME. By contrast, however, the 3'-AG to tG mutant was spliced and retained IME function. Moreover, heterologous introns, which did not show IME in S. cerevisiae, gained splicing competency and IME ability by substitutions to the S. cerevisiae-type 5'-SS and BPS sequences. Intriguingly, several deletion mutants between the 5'-SS and BPS in introns exhibited high levels of IME despite a loss in splicing competency. In most cases, further deletions or substitutions did not recover splicing competency and were found to decrease IME. However, a 16-nt variant consisting of the conserved 5'-SS and BPS sequences and 3'-CAG showed an IME level comparable with that of the wild-type intron. These results indicate that IME can be independent of splicing in S. cerevisiae while intron sequences at the 5'-SS and BPS play an essential role in IME.
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Affiliation(s)
- Hiroki Kikuta
- Division of Applied Chemistry, Graduate School of Sciences and Technology for Innovation, Yamaguchi University, 2-16-1 Tokiwadai, Ube 755-8611, Japan
| | - Satoshi Goto
- Division of Applied Chemistry, Graduate School of Sciences and Technology for Innovation, Yamaguchi University, 2-16-1 Tokiwadai, Ube 755-8611, Japan
| | - Masaki Kondo
- Division of Applied Chemistry, Graduate School of Sciences and Technology for Innovation, Yamaguchi University, 2-16-1 Tokiwadai, Ube 755-8611, Japan
| | - Rinji Akada
- Division of Applied Chemistry, Graduate School of Sciences and Technology for Innovation, Yamaguchi University, 2-16-1 Tokiwadai, Ube 755-8611, Japan; Research Center for Thermotolerant Microbial Resources, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8315, Japan; Yamaguchi University Biomedical Engineering Center, 2-16-1 Tokiwadai, Ube 755-8611, Japan
| | - Hisashi Hoshida
- Division of Applied Chemistry, Graduate School of Sciences and Technology for Innovation, Yamaguchi University, 2-16-1 Tokiwadai, Ube 755-8611, Japan; Research Center for Thermotolerant Microbial Resources, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8315, Japan; Yamaguchi University Biomedical Engineering Center, 2-16-1 Tokiwadai, Ube 755-8611, Japan.
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17
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Jespersen N, Monrroy L, Barandun J. Impact of Genome Reduction in Microsporidia. EXPERIENTIA SUPPLEMENTUM (2012) 2022; 114:1-42. [PMID: 35543997 DOI: 10.1007/978-3-030-93306-7_1] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Microsporidia represent an evolutionary outlier in the tree of life and occupy the extreme edge of the eukaryotic domain with some of their biological features. Many of these unicellular fungi-like organisms have reduced their genomic content to potentially the lowest limit. With some of the most compacted eukaryotic genomes, microsporidia are excellent model organisms to study reductive evolution and its functional consequences. While the growing number of sequenced microsporidian genomes have elucidated genome composition and organization, a recent increase in complementary post-genomic studies has started to shed light on the impacts of genome reduction in these unique pathogens. This chapter will discuss the biological framework enabling genome minimization and will use one of the most ancient and essential macromolecular complexes, the ribosome, to illustrate the effects of extreme genome reduction on a structural, molecular, and cellular level. We outline how reductive evolution in microsporidia has shaped DNA organization, the composition and function of the ribosome, and the complexity of the ribosome biogenesis process. Studying compacted mechanisms, processes, or macromolecular machines in microsporidia illuminates their unique lifestyle and provides valuable insights for comparative eukaryotic structural biology.
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Affiliation(s)
- Nathan Jespersen
- Department of Molecular Biology, The Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå Centre for Microbial Research (UCMR), Science for Life Laboratory, Umeå University, Umeå, Sweden.
| | - Leonardo Monrroy
- Department of Molecular Biology, The Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå Centre for Microbial Research (UCMR), Science for Life Laboratory, Umeå University, Umeå, Sweden
| | - Jonas Barandun
- Department of Molecular Biology, The Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå Centre for Microbial Research (UCMR), Science for Life Laboratory, Umeå University, Umeå, Sweden.
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18
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Humphreys IR, Pei J, Baek M, Krishnakumar A, Anishchenko I, Ovchinnikov S, Zhang J, Ness TJ, Banjade S, Bagde SR, Stancheva VG, Li XH, Liu K, Zheng Z, Barrero DJ, Roy U, Kuper J, Femández IS, Szakal B, Branzei D, Rizo J, Kisker C, Greene EC, Biggins S, Keeney S, Miller EA, Fromme JC, Hendrickson TL, Cong Q, Baker D. Computed structures of core eukaryotic protein complexes. Science 2021; 374:eabm4805. [PMID: 34762488 PMCID: PMC7612107 DOI: 10.1126/science.abm4805] [Citation(s) in RCA: 251] [Impact Index Per Article: 83.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Protein-protein interactions play critical roles in biology, but the structures of many eukaryotic protein complexes are unknown, and there are likely many interactions not yet identified. We take advantage of advances in proteome-wide amino acid coevolution analysis and deep-learning–based structure modeling to systematically identify and build accurate models of core eukaryotic protein complexes within the Saccharomyces cerevisiae proteome. We use a combination of RoseTTAFold and AlphaFold to screen through paired multiple sequence alignments for 8.3 million pairs of yeast proteins, identify 1505 likely to interact, and build structure models for 106 previously unidentified assemblies and 806 that have not been structurally characterized. These complexes, which have as many as five subunits, play roles in almost all key processes in eukaryotic cells and provide broad insights into biological function.
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Affiliation(s)
- Ian R. Humphreys
- Department of Biochemistry, University of Washington, Seattle, WA, USA
- Institute for Protein Design, University of Washington, Seattle, WA, USA
| | - Jimin Pei
- Eugene McDermott Center for Human Growth and Development, University of Texas Southwestern Medical Center, Dallas, TX, USA
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Minkyung Baek
- Department of Biochemistry, University of Washington, Seattle, WA, USA
- Institute for Protein Design, University of Washington, Seattle, WA, USA
| | - Aditya Krishnakumar
- Department of Biochemistry, University of Washington, Seattle, WA, USA
- Institute for Protein Design, University of Washington, Seattle, WA, USA
| | - Ivan Anishchenko
- Department of Biochemistry, University of Washington, Seattle, WA, USA
- Institute for Protein Design, University of Washington, Seattle, WA, USA
| | - Sergey Ovchinnikov
- Faculty of Arts and Sciences, Division of Science, Harvard University, Cambridge, MA, USA
- John Harvard Distinguished Science Fellowship Program, Harvard University, Cambridge, MA, USA
| | - Jing Zhang
- Eugene McDermott Center for Human Growth and Development, University of Texas Southwestern Medical Center, Dallas, TX, USA
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Travis J. Ness
- Department of Chemistry, Wayne State University, Detroit, MI, USA
| | - Sudeep Banjade
- Department of Molecular Biology & Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY, USA
| | - Saket R. Bagde
- Department of Molecular Biology & Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY, USA
| | | | - Xiao-Han Li
- MRC Laboratory of Molecular Biology, Cambridge, CB2 0QH, UK
| | - Kaixian Liu
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY
| | - Zhi Zheng
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY
- Gerstner Sloan Kettering Graduate School of Biomedical Sciences, New York, NY
| | - Daniel J. Barrero
- Howard Hughes Medical Institute, Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
| | - Upasana Roy
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY, USA
| | - Jochen Kuper
- Rudolf Virchow Center for Integrative and Translational Bioimaging, University of Würzburg, Würzburg, Germany
| | - Israel S. Femández
- Department of Structural Biology, St Jude Children's Research Hospital, Memphis, TN, USA
| | - Barnabas Szakal
- IFOM, the FIRC Institute of Molecular Oncology, Via Adamello 16, 20139, Milan, Italy
| | - Dana Branzei
- IFOM, the FIRC Institute of Molecular Oncology, Via Adamello 16, 20139, Milan, Italy
- Istituto di Genetica Molecolare, Consiglio Nazionale delle Ricerche (IGM-CNR), Via Abbiategrasso 207, 27100, Pavia, Italy
| | - Josep Rizo
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX, USA
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX, USA
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Caroline Kisker
- Rudolf Virchow Center for Integrative and Translational Bioimaging, University of Würzburg, Würzburg, Germany
| | - Eric C. Greene
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY, USA
| | - Sue Biggins
- Howard Hughes Medical Institute, Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
| | - Scott Keeney
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY
- Gerstner Sloan Kettering Graduate School of Biomedical Sciences, New York, NY
- Howard Hughes Medical Institute, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | | | - J. Christopher Fromme
- Department of Molecular Biology & Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY, USA
| | | | - Qian Cong
- Eugene McDermott Center for Human Growth and Development, University of Texas Southwestern Medical Center, Dallas, TX, USA
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - David Baker
- Department of Biochemistry, University of Washington, Seattle, WA, USA
- Institute for Protein Design, University of Washington, Seattle, WA, USA
- Howard Hughes Medical Institute, University of Washington, Seattle, WA, USA
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19
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Yueh LY, Tseng YT, Chu CY, Lo KY. The dedicated chaperones of eL43, Puf6 and Loc1, can also bind RPL43 mRNA and regulate the production of this ribosomal protein. J Biochem 2021; 171:85-96. [PMID: 34661244 DOI: 10.1093/jb/mvab110] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Accepted: 10/12/2021] [Indexed: 11/14/2022] Open
Abstract
The level of ribosome biogenesis is highly associated with cell growth rate. Because many ribosomal proteins have extraribosomal functions, overexpression or insufficient supply of these proteins may impair cellular growth. Therefore, the supply of ribosomal proteins is tightly controlled in response to rRNA syntheses and environmental stimuli. In our previous study, 2 RNA-binding proteins, Puf6 and Loc1, were identified as dedicated chaperones of the ribosomal protein eL43, with which they associate to maintain its protein level and proper loading. In this study, we demonstrate that Puf6 and Loc1 interact with RPL43 mRNA. Notably, Puf6 and Loc1 usually function as a dimeric complex to bind other mRNAs; however, in this instance, the individual proteins, but not the complex form, can bind RPL43 mRNA. Thus, Puf6 or Loc1 could bind RPL43 mRNA in loc1Δ or puf6Δ, respectively. The binding of Puf6 or Loc1 caused negative effects for eL43 production: decreased RNA stability and translation of RPL43A/B mRNA. The present results suggest that these dedicated chaperones control the protein levels of eL43 from the standpoint of stability and through regulating its production.
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Affiliation(s)
- Le-Yun Yueh
- Department of Agricultural Chemistry, College of Bioresources and Agriculture, National Taiwan University, Taipei 10617, Taiwan
| | - Yun-Ting Tseng
- Department of Agricultural Chemistry, College of Bioresources and Agriculture, National Taiwan University, Taipei 10617, Taiwan
| | - Chih-Yi Chu
- Department of Agricultural Chemistry, College of Bioresources and Agriculture, National Taiwan University, Taipei 10617, Taiwan
| | - Kai-Yin Lo
- Department of Agricultural Chemistry, College of Bioresources and Agriculture, National Taiwan University, Taipei 10617, Taiwan
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20
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Dwyer K, Agarwal N, Gega A, Ansari A. Proximity to the Promoter and Terminator Regions Regulates the Transcription Enhancement Potential of an Intron. Front Mol Biosci 2021; 8:712639. [PMID: 34291091 PMCID: PMC8287100 DOI: 10.3389/fmolb.2021.712639] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Accepted: 06/25/2021] [Indexed: 11/15/2022] Open
Abstract
An evolutionarily conserved feature of introns is their ability to enhance expression of genes that harbor them. Introns have been shown to regulate gene expression at the transcription and post-transcription level. The general perception is that a promoter-proximal intron is most efficient in enhancing gene expression and the effect diminishes with the increase in distance from the promoter. Here we show that the intron regains its positive influence on gene expression when in proximity to the terminator. We inserted ACT1 intron into different positions within IMD4 and INO1 genes. Transcription Run-On (TRO) analysis revealed that the transcription of both IMD4 and INO1 was maximal in constructs with a promoter-proximal intron and decreased with the increase in distance of the intron from the promoter. However, activation was partially restored when the intron was placed close to the terminator. We previously demonstrated that the promoter-proximal intron stimulates transcription by affecting promoter directionality through gene looping-mediated recruitment of termination factors in the vicinity of the promoter region. Here we show that the terminator-proximal intron also enhances promoter directionality and results in compact gene architecture with the promoter and terminator regions in close physical proximity. Furthermore, we show that both the promoter and terminator-proximal introns facilitate assembly or stabilization of the preinitiation complex (PIC) on the promoter. On the basis of these findings, we propose that proximity to both the promoter and the terminator regions affects the transcription regulatory potential of an intron, and the terminator-proximal intron enhances transcription by affecting both the assembly of preinitiation complex and promoter directionality.
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Affiliation(s)
| | | | | | - Athar Ansari
- Department of Biological Science, Wayne State University, Detroit, MI, United States
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21
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Parker MT, Knop K, Barton GJ, Simpson GG. 2passtools: two-pass alignment using machine-learning-filtered splice junctions increases the accuracy of intron detection in long-read RNA sequencing. Genome Biol 2021; 22:72. [PMID: 33648554 PMCID: PMC7919322 DOI: 10.1186/s13059-021-02296-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Accepted: 02/10/2021] [Indexed: 01/04/2023] Open
Abstract
Transcription of eukaryotic genomes involves complex alternative processing of RNAs. Sequencing of full-length RNAs using long reads reveals the true complexity of processing. However, the relatively high error rates of long-read sequencing technologies can reduce the accuracy of intron identification. Here we apply alignment metrics and machine-learning-derived sequence information to filter spurious splice junctions from long-read alignments and use the remaining junctions to guide realignment in a two-pass approach. This method, available in the software package 2passtools (https://github.com/bartongroup/2passtools), improves the accuracy of spliced alignment and transcriptome assembly for species both with and without existing high-quality annotations.
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Affiliation(s)
- Matthew T Parker
- School of Life Sciences, University of Dundee, Dow Street, Dundee, DD1 5EH, UK.
| | - Katarzyna Knop
- School of Life Sciences, University of Dundee, Dow Street, Dundee, DD1 5EH, UK
| | - Geoffrey J Barton
- School of Life Sciences, University of Dundee, Dow Street, Dundee, DD1 5EH, UK
| | - Gordon G Simpson
- School of Life Sciences, University of Dundee, Dow Street, Dundee, DD1 5EH, UK. .,James Hutton Institute, Invergowrie, DD2 5DA, UK.
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22
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Menees TM. Saccharomyces cerevisiae RNA lariat debranching enzyme, Dbr1p, is required for completion of reverse transcription by the retrovirus-like element Ty1 and cleaves branched Ty1 RNAs. Mol Genet Genomics 2021; 296:409-422. [PMID: 33464395 DOI: 10.1007/s00438-020-01753-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Accepted: 12/14/2020] [Indexed: 11/25/2022]
Abstract
RNA debranching enzymes are 2'-5' phosphodiesterases found in all eukaryotes. Their main role is cleavage of intron RNA lariat branch points, promoting RNA turnover via exonucleases. Consistent with this role, cells with reduced RNA debranching enzyme activity accumulate intron RNA lariats. The Saccharomyces cerevisiae RNA debranching enzyme Dbr1p is also a host factor for the yeast long terminal repeat (LTR) retrotransposon Ty1, a model for many aspects of retroviral replication. Fittingly, the human RNA debranching enzyme Dbr1 is a host factor for the human immunodeficiency virus, HIV-1. The yeast and human RNA debranching enzymes act at the reverse transcription stages for Ty1 and HIV-1, respectively. Although efficient production of full-length Ty1 cDNA requires Dbr1p, the findings reported here indicate that production of the earliest distinct cDNA product, minus strand strong stop DNA (-sssDNA), is equivalent in wild type and dbr1∆ mutant cells. Several branched Ty1 RNAs are shown to accumulate in dbr1∆ cells during retrotransposition. These data are consistent with creation of Ty1 RNA branches prior to Ty1 reverse transcription and their removal by Dbr1p to allow efficient extension of early cDNA products. The data support the possibility that RNA branch formation and cleavage play broadly shared, but unknown roles in retroviral and LTR retrotransposon reverse transcription.
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Affiliation(s)
- Thomas M Menees
- School of Biological and Chemical Sciences, University of Missouri-Kansas City, Kansas City, MO, USA.
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23
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Abstract
Host cell factors are integral to viral replication. Human immunodeficiency virus 1 (HIV-1), the retroviral agent of acquired immune deficiency syndrome, requires several host factors for reverse transcription of the viral genomic RNA (gRNA) into DNA shortly after viral entry. One of these host factors is the RNA lariat debranching enzyme (Dbr1), which cleaves the 2'-5' bond of branched and lariat RNAs. A recent study has revealed that Dbr1 cleaves HIV-1 gRNA lariats that form early after viral entry. Without Dbr1 activity, HIV-1 reverse transcription stalls, consistent with blockage of viral reverse transcriptase at gRNA branch points. These findings echo an earlier study with the long-terminal-repeat retrotransposon of Saccharomyces cerevisiae, Ty1, which is a retrovirus model. Currently, branching and debranching of viral gRNA are not widely recognized as features of HIV-1 replication, and the role of a gRNA lariat is not known. Future studies will determine whether these gRNA dynamics represent fundamental features of retroviral biology and whether they occur for other positive-sense RNA viruses.
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Affiliation(s)
- Thomas M Menees
- School of Biological and Chemical Sciences, University of Missouri-Kansas City, Kansas City, Missouri 64110, USA;
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24
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Kaeser G, Chun J. Brain cell somatic gene recombination and its phylogenetic foundations. J Biol Chem 2020; 295:12786-12795. [PMID: 32699111 PMCID: PMC7476723 DOI: 10.1074/jbc.rev120.009192] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Revised: 07/22/2020] [Indexed: 12/19/2022] Open
Abstract
A new form of somatic gene recombination (SGR) has been identified in the human brain that affects the Alzheimer's disease gene, amyloid precursor protein (APP). SGR occurs when a gene sequence is cut and recombined within a single cell's genomic DNA, generally independent of DNA replication and the cell cycle. The newly identified brain SGR produces genomic complementary DNAs (gencDNAs) lacking introns, which integrate into locations distinct from germline loci. This brief review will present an overview of likely related recombination mechanisms and genomic cDNA-like sequences that implicate evolutionary origins for brain SGR. Similarities and differences exist between brain SGR and VDJ recombination in the immune system, the first identified SGR form that now has a well-defined enzymatic machinery. Both require gene transcription, but brain SGR uses an RNA intermediate and reverse transcriptase (RT) activity, which are characteristics shared with endogenous retrotransposons. The identified gencDNAs have similarities to other cDNA-like sequences existing throughout phylogeny, including intron-less genes and inactive germline processed pseudogenes, with likely overlapping biosynthetic processes. gencDNAs arise somatically in an individual to produce multiple copies; can be functional; appear most frequently within postmitotic cells; have diverse sequences; change with age; and can change with disease state. Normally occurring brain SGR may represent a mechanism for gene optimization and long-term cellular memory, whereas its dysregulation could underlie multiple brain disorders and, potentially, other diseases like cancer. The involvement of RT activity implicates already Food and Drug Administration-approved RT inhibitors as possible near-term interventions for managing SGR-associated diseases and suggest next-generation therapeutics targeting SGR elements.
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Affiliation(s)
- Gwendolyn Kaeser
- Degenerative Disease Program at the Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California, USA
| | - Jerold Chun
- Degenerative Disease Program at the Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California, USA
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25
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Kurosaki T, Popp MW, Maquat LE. Quality and quantity control of gene expression by nonsense-mediated mRNA decay. Nat Rev Mol Cell Biol 2020; 20:406-420. [PMID: 30992545 DOI: 10.1038/s41580-019-0126-2] [Citation(s) in RCA: 446] [Impact Index Per Article: 111.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Nonsense-mediated mRNA decay (NMD) is one of the best characterized and most evolutionarily conserved cellular quality control mechanisms. Although NMD was first found to target one-third of mutated, disease-causing mRNAs, it is now known to also target ~10% of unmutated mammalian mRNAs to facilitate appropriate cellular responses - adaptation, differentiation or death - to environmental changes. Mutations in NMD genes in humans are associated with intellectual disability and cancer. In this Review, we discuss how NMD serves multiple purposes in human cells by degrading both mutated mRNAs to protect the integrity of the transcriptome and normal mRNAs to control the quantities of unmutated transcripts.
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Affiliation(s)
- Tatsuaki Kurosaki
- Department of Biochemistry and Biophysics, School of Medicine and Dentistry, University of Rochester, Rochester, NY, USA.,Center for RNA Biology, University of Rochester, Rochester, NY, USA
| | - Maximilian W Popp
- Department of Biochemistry and Biophysics, School of Medicine and Dentistry, University of Rochester, Rochester, NY, USA.,Center for RNA Biology, University of Rochester, Rochester, NY, USA
| | - Lynne E Maquat
- Department of Biochemistry and Biophysics, School of Medicine and Dentistry, University of Rochester, Rochester, NY, USA. .,Center for RNA Biology, University of Rochester, Rochester, NY, USA.
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26
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Bradshaw M, Grewe F, Thomas A, Harrison CH, Lindgren H, Muggia L, St Clair LL, Lumbsch HT, Leavitt SD. Characterizing the ribosomal tandem repeat and its utility as a DNA barcode in lichen-forming fungi. BMC Evol Biol 2020; 20:2. [PMID: 31906844 PMCID: PMC6945747 DOI: 10.1186/s12862-019-1571-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Accepted: 12/19/2019] [Indexed: 02/08/2023] Open
Abstract
Background Regions within the nuclear ribosomal operon are a major tool for inferring evolutionary relationships and investigating diversity in fungi. In spite of the prevalent use of ribosomal markers in fungal research, central features of nuclear ribosomal DNA (nrDNA) evolution are poorly characterized for fungi in general, including lichenized fungi. The internal transcribed spacer (ITS) region of the nrDNA has been adopted as the primary DNA barcode identification marker for fungi. However, little is known about intragenomic variation in the nrDNA in symbiotic fungi. In order to better understand evolution of nrDNA and the utility of the ITS region for barcode identification of lichen-forming fungal species, we generated nearly complete nuclear ribosomal operon sequences from nine species in the Rhizoplaca melanophthalma species complex using short reads from high-throughput sequencing. Results We estimated copy numbers for the nrDNA operon, ranging from nine to 48 copies for members of this complex, and found low levels of intragenomic variation in the standard barcode region (ITS). Monophyly of currently described species in this complex was supported in phylogenetic inferences based on the ITS, 28S, intergenic spacer region, and some intronic regions, independently; however, a phylogenetic inference based on the 18S provided much lower resolution. Phylogenetic analysis of concatenated ITS and intergenic spacer sequence data generated from 496 specimens collected worldwide revealed previously unrecognized lineages in the nrDNA phylogeny. Conclusions The results from our study support the general assumption that the ITS region of the nrDNA is an effective barcoding marker for fungi. For the R. melanophthalma group, the limited amount of potential intragenomic variability in the ITS region did not correspond to fixed diagnostic nucleotide position characters separating taxa within this species complex. Previously unrecognized lineages inferred from ITS sequence data may represent undescribed species-level lineages or reflect uncharacterized aspects of nrDNA evolution in the R. melanophthalma species complex.
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Affiliation(s)
- Michael Bradshaw
- Department of Biology, Brigham Young University, 4102 Life Science Building, Provo, UT, 84602, USA
| | - Felix Grewe
- Grainger Bioinformatics Center, The Field Museum, Chicago, IL, USA
| | - Anne Thomas
- Department of Biology, Brigham Young University, 4102 Life Science Building, Provo, UT, 84602, USA
| | - Cody H Harrison
- Department of Biology, Brigham Young University, 4102 Life Science Building, Provo, UT, 84602, USA
| | | | - Lucia Muggia
- Department of Life Sciences, University of Trieste, via Giorgieri 10, 34127, Trieste, Italy
| | - Larry L St Clair
- Department of Biology, Brigham Young University, 4102 Life Science Building, Provo, UT, 84602, USA.,M. L. Bean Life Science Museum, Brigham Young University, 4102 Life Science Building, Provo, UT, 84602, USA
| | | | - Steven D Leavitt
- Department of Biology, Brigham Young University, 4102 Life Science Building, Provo, UT, 84602, USA. .,M. L. Bean Life Science Museum, Brigham Young University, 4102 Life Science Building, Provo, UT, 84602, USA.
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27
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Nguyen H, Das U, Xie J. Genome-wide evolution of wobble base-pairing nucleotides of branchpoint motifs with increasing organismal complexity. RNA Biol 2019; 17:311-324. [PMID: 31814500 DOI: 10.1080/15476286.2019.1697548] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
Abstract
How have the branchpoint motifs evolved in organisms of different complexity? Here we identified and examined the consensus motifs (R1C2T3R4A5Y6, R: A or G, Y: C or T) of 898 fungal genomes. In Ascomycota unicellular yeasts, the G4/A4 ratio is mostly (98%) below 0.125 but increases sharply in multicellular species by about 40 times on average, and in the more complex Basidiomycota, it increases further by about 7 times. The global G4 increase is consistent with A4 to G4 transitions in evolution. Of the G4/A4-interacting amino acids of the branchpoint binding protein MSL5 (SF1) and the HSH155 (SF3B1), as well as the 5' splice sites (SS) and U2 snRNA genes, the 5' SS G3/A3 co-vary with the G4 to some extent. However, corresponding increase of the G4-complementary GCAGTA-U2 gene is rare, suggesting wobble-base pairing between the G4-containing branchpoint motif and GTAGTA-U2 in most of these species. Interestingly, the G4/A4 ratio correlates well with the abundance of alternative splicing in the two phyla, and G4 enriched significantly at the alternative 3' SS of genes in RNA metabolism, kinases and membrane proteins. Similar wobble nucleotides also enriched at the 3' SS of multicellular fungi with only thousands of protein-coding genes. Thus, branchpoint motifs have evolved U2-complementarity in unicellular Ascomycota yeasts, but have gradually gained more wobble base-pairing nucleotides in fungi of higher complexity, likely to destabilize branchpoint motif-U2 interaction and/or branchpoint A protrusion for alternative splicing. This implies an important role of relaxing the branchpoint signals in the multicellularity and further complexity of fungi.
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Affiliation(s)
- Hai Nguyen
- Department of Physiology & Pathophysiology, Max Rady College of Medicine, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, Canada.,Department of Applied Computer Sciences, University of Winnipeg, Winnipeg, Canada
| | - Urmi Das
- Department of Physiology & Pathophysiology, Max Rady College of Medicine, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, Canada
| | - Jiuyong Xie
- Department of Physiology & Pathophysiology, Max Rady College of Medicine, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, Canada
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28
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Abstract
The spliceosome removes introns from messenger RNA precursors (pre-mRNA). Decades of biochemistry and genetics combined with recent structural studies of the spliceosome have produced a detailed view of the mechanism of splicing. In this review, we aim to make this mechanism understandable and provide several videos of the spliceosome in action to illustrate the intricate choreography of splicing. The U1 and U2 small nuclear ribonucleoproteins (snRNPs) mark an intron and recruit the U4/U6.U5 tri-snRNP. Transfer of the 5' splice site (5'SS) from U1 to U6 snRNA triggers unwinding of U6 snRNA from U4 snRNA. U6 folds with U2 snRNA into an RNA-based active site that positions the 5'SS at two catalytic metal ions. The branch point (BP) adenosine attacks the 5'SS, producing a free 5' exon. Removal of the BP adenosine from the active site allows the 3'SS to bind, so that the 5' exon attacks the 3'SS to produce mature mRNA and an excised lariat intron.
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Affiliation(s)
- Max E Wilkinson
- MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, United Kingdom; ,
| | - Clément Charenton
- MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, United Kingdom; ,
| | - Kiyoshi Nagai
- MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, United Kingdom; ,
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29
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Parenteau J, Abou Elela S. Introns: Good Day Junk Is Bad Day Treasure. Trends Genet 2019; 35:923-934. [PMID: 31668856 DOI: 10.1016/j.tig.2019.09.010] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Revised: 08/28/2019] [Accepted: 09/19/2019] [Indexed: 02/01/2023]
Abstract
Introns are ubiquitous in eukaryotic transcripts. They are often viewed as junk RNA but the huge energetic burden of transcribing, removing, and degrading them suggests a significant evolutionary advantage. Ostensibly, an intron functions within the host pre-mRNA to regulate its splicing, transport, and degradation. However, recent studies have revealed an entirely new class of trans-acting functions where the presence of intronic RNA in the cell impacts the expression of other genes in trans. Here, we review possible new mechanisms of intron functions, with a focus on the role of yeast introns in regulating the cell growth response to starvation.
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Affiliation(s)
- Julie Parenteau
- Département de microbiologie et d'infectiologie, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Sherbrooke, QC J1E 4K8, Canada
| | - Sherif Abou Elela
- Département de microbiologie et d'infectiologie, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Sherbrooke, QC J1E 4K8, Canada.
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30
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Li X, Liu S, Zhang L, Issaian A, Hill RC, Espinosa S, Shi S, Cui Y, Kappel K, Das R, Hansen KC, Zhou ZH, Zhao R. A unified mechanism for intron and exon definition and back-splicing. Nature 2019; 573:375-380. [PMID: 31485080 PMCID: PMC6939996 DOI: 10.1038/s41586-019-1523-6] [Citation(s) in RCA: 108] [Impact Index Per Article: 21.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2019] [Accepted: 08/01/2019] [Indexed: 01/07/2023]
Abstract
The molecular mechanisms of exon definition and back-splicing are fundamental unanswered questions in pre-mRNA splicing. Here we report cryo-electron microscopy structures of the yeast spliceosomal E complex assembled on introns, providing a view of the earliest event in the splicing cycle that commits pre-mRNAs to splicing. The E complex architecture suggests that the same spliceosome can assemble across an exon, and that it either remodels to span an intron for canonical linear splicing (typically on short exons) or catalyses back-splicing to generate circular RNA (on long exons). The model is supported by our experiments, which show that an E complex assembled on the middle exon of yeast EFM5 or HMRA1 can be chased into circular RNA when the exon is sufficiently long. This simple model unifies intron definition, exon definition, and back-splicing through the same spliceosome in all eukaryotes and should inspire experiments in many other systems to understand the mechanism and regulation of these processes.
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Affiliation(s)
- Xueni Li
- Department of Biochemistry and Molecular Genetics, School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Shiheng Liu
- Department of Microbiology, Immunology, and Molecular Genetics, UCLA, Los Angeles, CA, USA
- Electron Imaging Center for Nanomachines, UCLA, Los Angeles, CA, USA
| | - Lingdi Zhang
- Department of Biochemistry and Molecular Genetics, School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Aaron Issaian
- Department of Biochemistry and Molecular Genetics, School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Ryan C Hill
- Department of Biochemistry and Molecular Genetics, School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Sara Espinosa
- Department of Biochemistry and Molecular Genetics, School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Shasha Shi
- Department of Biochemistry and Molecular Genetics, School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Yanxiang Cui
- Electron Imaging Center for Nanomachines, UCLA, Los Angeles, CA, USA
| | - Kalli Kappel
- Biophysics Program, Stanford University, Stanford, CA, USA
| | - Rhiju Das
- Biophysics Program, Stanford University, Stanford, CA, USA
- Department of Biochemistry, Stanford University, Stanford, CA, USA
- Department of Physics, Stanford University, Stanford, CA, USA
| | - Kirk C Hansen
- Department of Biochemistry and Molecular Genetics, School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Z Hong Zhou
- Department of Microbiology, Immunology, and Molecular Genetics, UCLA, Los Angeles, CA, USA.
- Electron Imaging Center for Nanomachines, UCLA, Los Angeles, CA, USA.
| | - Rui Zhao
- Department of Biochemistry and Molecular Genetics, School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO, USA.
- RNA Bioscience Initiative, School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO, USA.
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31
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Talkish J, Igel H, Perriman RJ, Shiue L, Katzman S, Munding EM, Shelansky R, Donohue JP, Ares M. Rapidly evolving protointrons in Saccharomyces genomes revealed by a hungry spliceosome. PLoS Genet 2019; 15:e1008249. [PMID: 31437148 PMCID: PMC6726248 DOI: 10.1371/journal.pgen.1008249] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2019] [Revised: 09/04/2019] [Accepted: 06/15/2019] [Indexed: 12/14/2022] Open
Abstract
Introns are a prevalent feature of eukaryotic genomes, yet their origins and contributions to genome function and evolution remain mysterious. In budding yeast, repression of the highly transcribed intron-containing ribosomal protein genes (RPGs) globally increases splicing of non-RPG transcripts through reduced competition for the spliceosome. We show that under these “hungry spliceosome” conditions, splicing occurs at more than 150 previously unannotated locations we call protointrons that do not overlap known introns. Protointrons use a less constrained set of splice sites and branchpoints than standard introns, including in one case AT-AC in place of GT-AG. Protointrons are not conserved in all closely related species, suggesting that most are not under positive selection and are fated to disappear. Some are found in non-coding RNAs (e. g. CUTs and SUTs), where they may contribute to the creation of new genes. Others are found across boundaries between noncoding and coding sequences, or within coding sequences, where they offer pathways to the creation of new protein variants, or new regulatory controls for existing genes. We define protointrons as (1) nonconserved intron-like sequences that are (2) infrequently spliced, and importantly (3) are not currently understood to contribute to gene expression or regulation in the way that standard introns function. A very few protointrons in S. cerevisiae challenge this classification by their increased splicing frequency and potential function, consistent with the proposed evolutionary process of “intronization”, whereby new standard introns are created. This snapshot of intron evolution highlights the important role of the spliceosome in the expansion of transcribed genomic sequence space, providing a pathway for the rare events that may lead to the birth of new eukaryotic genes and the refinement of existing gene function. The protein coding information in eukaryotic genes is broken by intervening sequences called introns that are removed from RNA during transcription by a large protein-RNA complex called the spliceosome. Where introns come from and how the spliceosome contributes to genome evolution are open questions. In this study, we find more than 150 new places in the yeast genome that are recognized by the spliceosome and spliced out as introns. Since they appear to have arisen very recently in evolution by sequence drift and do not appear to contribute to gene expression or its regulation, we call these protointrons. Protointrons are found in both protein-coding and non-coding RNAs and are not efficiently removed by the splicing machinery. Although most protointrons are not conserved and will likely disappear as evolution proceeds, a few are spliced more efficiently, and are located where they might begin to play functional roles in gene expression, as predicted by the proposed process of intronization. The challenge now is to understand how spontaneously appearing splicing events like protointrons might contribute to the creation of new genes, new genetic controls, and new protein isoforms as genomes evolve.
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Affiliation(s)
- Jason Talkish
- Center for Molecular Biology of RNA, Department of Molecular, Cell & Developmental Biology, University of California, Santa Cruz, Santa Cruz, California, United States of America
| | - Haller Igel
- Center for Molecular Biology of RNA, Department of Molecular, Cell & Developmental Biology, University of California, Santa Cruz, Santa Cruz, California, United States of America
| | - Rhonda J. Perriman
- Center for Molecular Biology of RNA, Department of Molecular, Cell & Developmental Biology, University of California, Santa Cruz, Santa Cruz, California, United States of America
| | - Lily Shiue
- Center for Molecular Biology of RNA, Department of Molecular, Cell & Developmental Biology, University of California, Santa Cruz, Santa Cruz, California, United States of America
| | - Sol Katzman
- Department of Biomolecular Engineering, University of California, Santa Cruz, Santa Cruz, California, United States of America
| | - Elizabeth M. Munding
- Center for Molecular Biology of RNA, Department of Molecular, Cell & Developmental Biology, University of California, Santa Cruz, Santa Cruz, California, United States of America
| | - Robert Shelansky
- Department of Biomolecular Engineering, University of California, Santa Cruz, Santa Cruz, California, United States of America
| | - John Paul Donohue
- Center for Molecular Biology of RNA, Department of Molecular, Cell & Developmental Biology, University of California, Santa Cruz, Santa Cruz, California, United States of America
| | - Manuel Ares
- Center for Molecular Biology of RNA, Department of Molecular, Cell & Developmental Biology, University of California, Santa Cruz, Santa Cruz, California, United States of America
- * E-mail:
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32
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Hudson AJ, McWatters DC, Bowser BA, Moore AN, Larue GE, Roy SW, Russell AG. Patterns of conservation of spliceosomal intron structures and spliceosome divergence in representatives of the diplomonad and parabasalid lineages. BMC Evol Biol 2019; 19:162. [PMID: 31375061 PMCID: PMC6679479 DOI: 10.1186/s12862-019-1488-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Accepted: 07/23/2019] [Indexed: 11/10/2022] Open
Abstract
Background Two spliceosomal intron types co-exist in eukaryotic precursor mRNAs and are excised by distinct U2-dependent and U12-dependent spliceosomes. In the diplomonad Giardia lamblia, small nuclear (sn) RNAs show hybrid characteristics of U2- and U12-dependent spliceosomal snRNAs and 5 of 11 identified remaining spliceosomal introns are trans-spliced. It is unknown whether unusual intron and spliceosome features are conserved in other diplomonads. Results We have identified spliceosomal introns, snRNAs and proteins from two additional diplomonads for which genome information is currently available, Spironucleus vortens and Spironucleus salmonicida, as well as relatives, including 6 verified cis-spliceosomal introns in S. vortens. Intron splicing signals are mostly conserved between the Spironucleus species and G. lamblia. Similar to ‘long’ G. lamblia introns, RNA secondary structural potential is evident for ‘long’ (> 50 nt) Spironucleus introns as well as introns identified in the parabasalid Trichomonas vaginalis. Base pairing within these introns is predicted to constrain spatial distances between splice junctions to similar distances seen in the shorter and uniformly-sized introns in these organisms. We find that several remaining Spironucleus spliceosomal introns are ancient. We identified a candidate U2 snRNA from S. vortens, and U2 and U5 snRNAs in S. salmonicida; cumulatively, illustrating significant snRNA differences within some diplomonads. Finally, we studied spliceosomal protein complements and find protein sets in Giardia, Spironucleus and Trepomonas sp. PC1 highly- reduced but well conserved across the clade, with between 44 and 62 out of 174 studied spliceosomal proteins detectable. Comparison with more distant relatives revealed a highly nested pattern, with the more intron-rich fornicate Kipferlia bialata retaining 87 total proteins including nearly all those observed in the diplomonad representatives, and the oxymonad Monocercomonoides retaining 115 total proteins including nearly all those observed in K. bialata. Conclusions Comparisons in diplomonad representatives and species of other closely-related metamonad groups indicates similar patterns of intron structural conservation and spliceosomal protein composition but significant divergence of snRNA structure in genomically-reduced species. Relative to other eukaryotes, loss of evolutionarily-conserved snRNA domains and common sets of spliceosomal proteins point to a more streamlined splicing mechanism, where intron sequences and structures may be functionally compensating for the minimalization of spliceosome components. Electronic supplementary material The online version of this article (10.1186/s12862-019-1488-y) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Andrew J Hudson
- Alberta RNA Research and Training Institute, University of Lethbridge, Lethbridge, AB, Canada.,Department of Biological Sciences, University of Lethbridge, Lethbridge, AB, Canada
| | - David C McWatters
- Alberta RNA Research and Training Institute, University of Lethbridge, Lethbridge, AB, Canada.,Department of Biological Sciences, University of Lethbridge, Lethbridge, AB, Canada
| | - Bradley A Bowser
- Molecular Cell Biology, University of California-Merced, Merced, CA, USA
| | - Ashley N Moore
- Alberta RNA Research and Training Institute, University of Lethbridge, Lethbridge, AB, Canada.,Department of Biological Sciences, University of Lethbridge, Lethbridge, AB, Canada
| | - Graham E Larue
- Molecular Cell Biology, University of California-Merced, Merced, CA, USA
| | - Scott W Roy
- Molecular Cell Biology, University of California-Merced, Merced, CA, USA.,Department of Biology, San Francisco State University, San Francisco, California, USA
| | - Anthony G Russell
- Alberta RNA Research and Training Institute, University of Lethbridge, Lethbridge, AB, Canada. .,Department of Biological Sciences, University of Lethbridge, Lethbridge, AB, Canada.
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33
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Talkish J, Igel H, Perriman RJ, Shiue L, Katzman S, Munding EM, Shelansky R, Donohue JP, Ares M. Rapidly evolving protointrons in Saccharomyces genomes revealed by a hungry spliceosome. PLoS Genet 2019; 15:e1008249. [PMID: 31437148 DOI: 10.1101/515197] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2019] [Revised: 09/04/2019] [Accepted: 06/15/2019] [Indexed: 05/28/2023] Open
Abstract
Introns are a prevalent feature of eukaryotic genomes, yet their origins and contributions to genome function and evolution remain mysterious. In budding yeast, repression of the highly transcribed intron-containing ribosomal protein genes (RPGs) globally increases splicing of non-RPG transcripts through reduced competition for the spliceosome. We show that under these "hungry spliceosome" conditions, splicing occurs at more than 150 previously unannotated locations we call protointrons that do not overlap known introns. Protointrons use a less constrained set of splice sites and branchpoints than standard introns, including in one case AT-AC in place of GT-AG. Protointrons are not conserved in all closely related species, suggesting that most are not under positive selection and are fated to disappear. Some are found in non-coding RNAs (e. g. CUTs and SUTs), where they may contribute to the creation of new genes. Others are found across boundaries between noncoding and coding sequences, or within coding sequences, where they offer pathways to the creation of new protein variants, or new regulatory controls for existing genes. We define protointrons as (1) nonconserved intron-like sequences that are (2) infrequently spliced, and importantly (3) are not currently understood to contribute to gene expression or regulation in the way that standard introns function. A very few protointrons in S. cerevisiae challenge this classification by their increased splicing frequency and potential function, consistent with the proposed evolutionary process of "intronization", whereby new standard introns are created. This snapshot of intron evolution highlights the important role of the spliceosome in the expansion of transcribed genomic sequence space, providing a pathway for the rare events that may lead to the birth of new eukaryotic genes and the refinement of existing gene function.
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Affiliation(s)
- Jason Talkish
- Center for Molecular Biology of RNA, Department of Molecular, Cell & Developmental Biology, University of California, Santa Cruz, Santa Cruz, California, United States of America
| | - Haller Igel
- Center for Molecular Biology of RNA, Department of Molecular, Cell & Developmental Biology, University of California, Santa Cruz, Santa Cruz, California, United States of America
| | - Rhonda J Perriman
- Center for Molecular Biology of RNA, Department of Molecular, Cell & Developmental Biology, University of California, Santa Cruz, Santa Cruz, California, United States of America
| | - Lily Shiue
- Center for Molecular Biology of RNA, Department of Molecular, Cell & Developmental Biology, University of California, Santa Cruz, Santa Cruz, California, United States of America
| | - Sol Katzman
- Department of Biomolecular Engineering, University of California, Santa Cruz, Santa Cruz, California, United States of America
| | - Elizabeth M Munding
- Center for Molecular Biology of RNA, Department of Molecular, Cell & Developmental Biology, University of California, Santa Cruz, Santa Cruz, California, United States of America
| | - Robert Shelansky
- Department of Biomolecular Engineering, University of California, Santa Cruz, Santa Cruz, California, United States of America
| | - John Paul Donohue
- Center for Molecular Biology of RNA, Department of Molecular, Cell & Developmental Biology, University of California, Santa Cruz, Santa Cruz, California, United States of America
| | - Manuel Ares
- Center for Molecular Biology of RNA, Department of Molecular, Cell & Developmental Biology, University of California, Santa Cruz, Santa Cruz, California, United States of America
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Fillinger RJ, Anderson MZ. Seasons of change: Mechanisms of genome evolution in human fungal pathogens. INFECTION, GENETICS AND EVOLUTION : JOURNAL OF MOLECULAR EPIDEMIOLOGY AND EVOLUTIONARY GENETICS IN INFECTIOUS DISEASES 2019; 70:165-174. [PMID: 30826447 DOI: 10.1016/j.meegid.2019.02.031] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Revised: 02/23/2019] [Accepted: 02/26/2019] [Indexed: 06/09/2023]
Abstract
Fungi are a diverse kingdom of organisms capable of thriving in various niches across the world including those in close association with multicellular eukaryotes. Fungal pathogens that contribute to human disease reside both within the host as commensal organisms of the microbiota and the environment. Their niche of origin dictates how infection initiates but also places specific selective pressures on the fungal pathogen that contributes to its genome organization and genetic repertoire. Recent efforts to catalogue genomic variation among major human fungal pathogens have unveiled evolutionary themes that shape the fungal genome. Mechanisms ranging from large scale changes such as aneuploidy and ploidy cycling as well as more targeted mutations like base substitutions and gene copy number variations contribute to the evolution of these species, which are often under multiple competing selective pressures with their host, environment, and other microbes. Here, we provide an overview of the major selective pressures and mechanisms acting to evolve the genome of clinically important fungal pathogens of humans.
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Affiliation(s)
- Robert J Fillinger
- Department of Microbial Infection and Immunity, The Ohio State University, Columbus, OH 43210, USA
| | - Matthew Z Anderson
- Department of Microbial Infection and Immunity, The Ohio State University, Columbus, OH 43210, USA; Department of Microbiology, The Ohio State University, Columbus, OH 43210, USA.
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Xiong F, Ren JJ, Yu Q, Wang YY, Kong LJ, Otegui MS, Wang XL. AtBUD13 affects pre-mRNA splicing and is essential for embryo development in Arabidopsis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2019; 98:714-726. [PMID: 30720904 DOI: 10.1111/tpj.14268] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Revised: 01/24/2019] [Accepted: 01/30/2019] [Indexed: 05/03/2023]
Abstract
Pre-mRNA splicing is an important step for gene expression regulation. Yeast Bud13p (bud-site selection protein 13) regulates the budding pattern and pre-mRNA splicing in yeast cells; however, no Bud13p homologs have been identified in plants. Here, we isolated two mutants that carry T-DNA insertions at the At1g31870 locus and shows early embryo lethality and seed abortion. At1g31870 encodes an Arabidopsis homolog of yeast Bud13p, AtBUD13. Although AtBUD13 homologs are widely distributed in eukaryotic organisms, phylogenetic analysis revealed that their protein domain organization is more complex in multicellular species. AtBUD13 is expressed throughout plant development including embryogenesis and AtBUD13 proteins is localized in the nucleus in Arabidopsis. RNA-seq analysis revealed that AtBUD13 mutation predominantly results in the intron retention, especially for shorter introns (≤100 bases). Within this group of genes, we identified 52 genes involved in embryogenesis, out of which 22 are involved in nucleic acid metabolism. Our results demonstrate that AtBUD13 plays critical roles in early embryo development by effecting pre-mRNA splicing.
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Affiliation(s)
- Feng Xiong
- National Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Taian, 271018, China
| | - Jing-Jing Ren
- National Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Taian, 271018, China
| | - Qin Yu
- National Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Taian, 271018, China
| | - Yu-Yi Wang
- National Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Taian, 271018, China
| | - Lan-Jing Kong
- National Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Taian, 271018, China
| | - Marisa S Otegui
- Departments of Botany and Genetics, University of Wisconsin-Madison, Madison, 53706, USA
- Laboratory of Cell and Molecular Biology, University of Wisconsin-Madison, Madison, 53706, USA
| | - Xiu-Ling Wang
- National Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Taian, 271018, China
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Plaschka C, Newman AJ, Nagai K. Structural Basis of Nuclear pre-mRNA Splicing: Lessons from Yeast. Cold Spring Harb Perspect Biol 2019; 11:cshperspect.a032391. [PMID: 30765413 DOI: 10.1101/cshperspect.a032391] [Citation(s) in RCA: 60] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Noncoding introns are removed from nuclear precursor messenger RNA (pre-mRNA) in a two-step phosphoryl transfer reaction by the spliceosome, a dynamic multimegadalton enzyme. Cryo-electron microscopy (cryo-EM) structures of the Saccharomyces cerevisiae spliceosome were recently determined in eight key states. Combined with the wealth of available genetic and biochemical data, these structures have revealed new insights into the mechanisms of spliceosome assembly, activation, catalysis, and disassembly. The structures show how a single RNA catalytic center forms during activation and accomplishes both steps of the splicing reaction. The structures reveal how spliceosomal helicases remodel the spliceosome for active site formation, substrate docking, reaction product undocking, and spliceosome disassembly and how they facilitate splice site proofreading. Although human spliceosomes contain additional proteins, their cryo-EM structures suggest that the underlying mechanism is conserved across all eukaryotes. In this review, we summarize the current structural understanding of pre-mRNA splicing.
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Affiliation(s)
- Clemens Plaschka
- MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, United Kingdom
| | - Andrew J Newman
- MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, United Kingdom
| | - Kiyoshi Nagai
- MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, United Kingdom
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37
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Xia X. RNA-Seq approach for accurate characterization of splicing efficiency of yeast introns. Methods 2019; 176:25-33. [PMID: 30926533 DOI: 10.1016/j.ymeth.2019.03.019] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2018] [Revised: 03/12/2019] [Accepted: 03/19/2019] [Indexed: 01/21/2023] Open
Abstract
Introns in different genes, or even different introns within the same gene, often have different splice sites and differ in splicing efficiency (SE). One expects mass-transcribed genes to have introns with higher SE than weakly transcribed genes. However, such a simple expectation cannot be tested directly because variable SE for these genes is often not measured. Mechanistically, SE should depend on signal strength at key splice sites (SS) such as 5'SS, 3'SS and branchpoint site (BPS), i.e., SE = F(5'SS, 3'SS, BPS). However, without SE, we again cannot model how these splice sites contribute to SE. Here I present an RNA-Seq approach to quantify SE for each of the 304 introns in yeast (Saccharomyces cerevisiae) genes, including 24 in the 5'UTR, by measuring 1) number of reads mapped to exon-exon junctions (NEE) as a proxy for the abundance of spliced form, and 2) number of reads mapped to exon-intron junction (NEI5 and NEI3 at 5' and 3' ends of intron) as a proxy for the abundance of unspliced form. The total mRNA is NTotal = NEE + p * NEI5 + (1-p) * NEI3, with the simplest p = 0.5 but statistical methods were presented to estimate p from data. An estimated p is needed because NEI5 is expected to be smaller than NEI3 due to 1) step 1 splicing occurs before step 2 so EI5 is broken before EI3, 2) enrichment of poly(A) mRNA by oligo-dT, and 3) 5' degradation. SE is defined as the proportion (NEE/NTotal). Application of the method shows that ribosomal protein messages are efficiently and mostly cotranscriptionally spliced. Yeast genes with long introns are also spliced efficiently. HAC1/YFL031W is poorly spliced partly because its splicing involves a nonspliceosome mechanism and partly because Ire1p, which participate in splicing HAC1, is hardly expressed. Many putative yeast genes have low SE, and some splice sites are incorrectly annotated.
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Affiliation(s)
- Xuhua Xia
- Department of Biology, University of Ottawa, 30 Marie Curie, Ottawa K1N 6N5, Canada; Ottawa Institute of Systems Biology, Ottawa, Ontario K1H 8M5, Canada.
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38
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Zhang L, Vielle A, Espinosa S, Zhao R. RNAs in the spliceosome: Insight from cryoEM structures. WILEY INTERDISCIPLINARY REVIEWS-RNA 2019; 10:e1523. [PMID: 30729694 DOI: 10.1002/wrna.1523] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Revised: 12/12/2018] [Accepted: 12/28/2018] [Indexed: 12/28/2022]
Abstract
Pre-mRNA splicing is catalyzed by the spliceosome, a multimegadalton RNA-protein complex. The spliceosome undergoes dramatic compositional and conformational changes through the splicing cycle, forming at least 10 distinct complexes. Recent high-resolution cryoEM structures of various spliceosomal complexes revealed unprecedented details of this large molecular machine. This review highlights insight into the structure and function of the spliceosomal RNA components obtained from these new structures, with a focus on the yeast spliceosome. This article is categorized under: RNA Processing > Splicing Mechanisms RNA Structure and Dynamics > RNA Structure, Dynamics, and Chemistry RNA Interactions with Proteins and Other Molecules > RNA-Protein Complexes.
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Affiliation(s)
- Lingdi Zhang
- Department of Biochemistry and Molecular Genetics, Anschutz Medical Campus, University of Colorado Denver, Aurora, Colorado
| | - Anne Vielle
- Department of Biochemistry and Molecular Genetics, Anschutz Medical Campus, University of Colorado Denver, Aurora, Colorado
| | - Sara Espinosa
- Department of Biochemistry and Molecular Genetics, Anschutz Medical Campus, University of Colorado Denver, Aurora, Colorado
| | - Rui Zhao
- Department of Biochemistry and Molecular Genetics, Anschutz Medical Campus, University of Colorado Denver, Aurora, Colorado
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39
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Excised linear introns regulate growth in yeast. Nature 2019; 565:606-611. [PMID: 30651636 DOI: 10.1038/s41586-018-0828-1] [Citation(s) in RCA: 92] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Accepted: 11/27/2018] [Indexed: 12/31/2022]
Abstract
Spliceosomal introns are ubiquitous non-coding RNAs that are typically destined for rapid debranching and degradation. Here we describe 34 excised introns in Saccharomyces cerevisiae that-despite being rapidly degraded in log-phase growth-accumulate as linear RNAs under either saturated-growth conditions or other stresses that cause prolonged inhibition of TORC1, which is a key integrator of growth signalling. Introns that become stabilized remain associated with components of the spliceosome and differ from other spliceosomal introns in having a short distance between their lariat branch point and 3' splice site, which is necessary and sufficient for their stabilization. Deletion of these unusual introns is disadvantageous in saturated conditions and causes aberrantly high growth rates in yeast that are chronically challenged with the TORC1 inhibitor rapamycin. The reintroduction of native or engineered stable introns suppresses this aberrant rapamycin response. Thus, excised introns function within the TOR growth-signalling network of S. cerevisiae and, more generally, excised spliceosomal introns can have biological functions.
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40
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Parenteau J, Maignon L, Berthoumieux M, Catala M, Gagnon V, Abou Elela S. Introns are mediators of cell response to starvation. Nature 2019; 565:612-617. [DOI: 10.1038/s41586-018-0859-7] [Citation(s) in RCA: 115] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Accepted: 12/07/2018] [Indexed: 11/09/2022]
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41
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Yan C, Wan R, Shi Y. Molecular Mechanisms of pre-mRNA Splicing through Structural Biology of the Spliceosome. Cold Spring Harb Perspect Biol 2019; 11:11/1/a032409. [PMID: 30602541 DOI: 10.1101/cshperspect.a032409] [Citation(s) in RCA: 92] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Precursor messenger RNA (pre-mRNA) splicing is executed by the spliceosome. In the past 3 years, cryoelectron microscopy (cryo-EM) structures have been elucidated for a majority of the yeast spliceosomal complexes and for a few human spliceosomes. During the splicing reaction, the dynamic spliceosome has an immobile core of about 20 protein and RNA components, which are organized around a conserved splicing active site. The divalent metal ions, coordinated by U6 small nuclear RNA (snRNA), catalyze the branching reaction and exon ligation. The spliceosome also contains a mobile but compositionally stable group of about 13 proteins and a portion of U2 snRNA, which facilitate substrate delivery into the splicing active site. The spliceosomal transitions are driven by the RNA-dependent ATPase/helicases, resulting in the recruitment and dissociation of specific splicing factors that enable the reaction. In summary, the spliceosome is a protein-directed metalloribozyme.
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Affiliation(s)
- Chuangye Yan
- Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Ruixue Wan
- Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Yigong Shi
- Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China.,Institute of Biology, Westlake Institute for Advanced Study, Westlake University, Hangzhou 310064, Zhejiang Province, China
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42
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Carrocci TJ, Neugebauer KM. Pre-mRNA Splicing in the Nuclear Landscape. COLD SPRING HARBOR SYMPOSIA ON QUANTITATIVE BIOLOGY 2019; 84:11-20. [PMID: 32493763 PMCID: PMC7384967 DOI: 10.1101/sqb.2019.84.040402] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Eukaryotic gene expression requires the cumulative activity of multiple molecular machines to synthesize and process newly transcribed pre-messenger RNA. Introns, the noncoding regions in pre-mRNA, must be removed by the spliceosome, which assembles on the pre-mRNA as it is transcribed by RNA polymerase II (Pol II). The assembly and activity of the spliceosome can be modulated by features including the speed of transcription elongation, chromatin, post-translational modifications of Pol II and histone tails, and other RNA processing events like 5'-end capping. Here, we review recent work that has revealed cooperation and coordination among co-transcriptional processing events and speculate on new avenues of research. We anticipate new mechanistic insights capable of unraveling the relative contribution of coupled processing to gene expression.
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Affiliation(s)
- Tucker J Carrocci
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06520, USA
| | - Karla M Neugebauer
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06520, USA
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43
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Gärtner F, Höner zu Siederdissen C, Müller L, Stadler PF. Coordinate systems for supergenomes. Algorithms Mol Biol 2018; 13:15. [PMID: 30258487 PMCID: PMC6151955 DOI: 10.1186/s13015-018-0133-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Accepted: 09/07/2018] [Indexed: 01/05/2023] Open
Abstract
BACKGROUND Genome sequences and genome annotation data have become available at ever increasing rates in response to the rapid progress in sequencing technologies. As a consequence the demand for methods supporting comparative, evolutionary analysis is also growing. In particular, efficient tools to visualize-omics data simultaneously for multiple species are sorely lacking. A first and crucial step in this direction is the construction of a common coordinate system. Since genomes not only differ by rearrangements but also by large insertions, deletions, and duplications, the use of a single reference genome is insufficient, in particular when the number of species becomes large. RESULTS The computational problem then becomes to determine an order and orientations of optimal local alignments that are as co-linear as possible with all the genome sequences. We first review the most prominent approaches to model the problem formally and then proceed to showing that it can be phrased as a particular variant of the Betweenness Problem. It is NP hard in general. As exact solutions are beyond reach for the problem sizes of practical interest, we introduce a collection of heuristic simplifiers to resolve ordering conflicts. CONCLUSION Benchmarks on real-life data ranging from bacterial to fly genomes demonstrate the feasibility of computing good common coordinate systems.
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Affiliation(s)
- Fabian Gärtner
- Competence Center for Scalable Data Services and Solutions Dresden/Leipzig, Universität Leipzig, Augustusplatz 12, 04107 Leipzig, Germany
- Bioinformatics Group, Department of Computer Science, Universität Leipzig, Härtelstraße 16–18, 04107 Leipzig, Germany
| | - Christian Höner zu Siederdissen
- Bioinformatics Group, Department of Computer Science, Universität Leipzig, Härtelstraße 16–18, 04107 Leipzig, Germany
- Interdisciplinary Center for Bioinformatics, Universität Leipzig, Härtelstraße 16–18, 04107 Leipzig, Germany
| | - Lydia Müller
- Competence Center for Scalable Data Services and Solutions Dresden/Leipzig, Universität Leipzig, Augustusplatz 12, 04107 Leipzig, Germany
- Interdisciplinary Center for Bioinformatics, Universität Leipzig, Härtelstraße 16–18, 04107 Leipzig, Germany
- Automatic Language Processing Group, Department of Computer Science, Universität Leipzig, Augustusplatz 12, 04107 Leipzig, Germany
| | - Peter F. Stadler
- Competence Center for Scalable Data Services and Solutions Dresden/Leipzig, Universität Leipzig, Augustusplatz 12, 04107 Leipzig, Germany
- Bioinformatics Group, Department of Computer Science, Universität Leipzig, Härtelstraße 16–18, 04107 Leipzig, Germany
- Interdisciplinary Center for Bioinformatics, Universität Leipzig, Härtelstraße 16–18, 04107 Leipzig, Germany
- Max Planck Institute for Mathematics in the Sciences, Inselstraße 22, 04103 Leipzig, Germany
- Department of Theoretical Chemistry, University of Vienna, Währinger Straße 17, 1090 Vienna, Austria
- Center for non-coding RNA in Technology and Health, Grønegårdsvej 3, 1870 Frederiksberg C, Denmark
- Santa Fe Institute, 1399 Hyde Park Rd., Santa Fe, NM 87501 USA
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Hiraga SI, Monerawela C, Katou Y, Shaw S, Clark KR, Shirahige K, Donaldson AD. Budding yeast Rif1 binds to replication origins and protects DNA at blocked replication forks. EMBO Rep 2018; 19:e46222. [PMID: 30104203 PMCID: PMC6123642 DOI: 10.15252/embr.201846222] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2018] [Revised: 07/17/2018] [Accepted: 07/23/2018] [Indexed: 11/28/2022] Open
Abstract
Despite its evolutionarily conserved function in controlling DNA replication, the chromosomal binding sites of the budding yeast Rif1 protein are not well understood. Here, we analyse genome-wide binding of budding yeast Rif1 by chromatin immunoprecipitation, during G1 phase and in S phase with replication progressing normally or blocked by hydroxyurea. Rif1 associates strongly with telomeres through interaction with Rap1. By comparing genomic binding of wild-type Rif1 and truncated Rif1 lacking the Rap1-interaction domain, we identify hundreds of Rap1-dependent and Rap1-independent chromosome interaction sites. Rif1 binds to centromeres, highly transcribed genes and replication origins in a Rap1-independent manner, associating with both early and late-initiating origins. Interestingly, Rif1 also binds around activated origins when replication progression is blocked by hydroxyurea, suggesting association with blocked forks. Using nascent DNA labelling and DNA combing techniques, we find that in cells treated with hydroxyurea, yeast Rif1 stabilises recently synthesised DNA Our results indicate that, in addition to controlling DNA replication initiation, budding yeast Rif1 plays an ongoing role after initiation and controls events at blocked replication forks.
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Affiliation(s)
| | | | - Yuki Katou
- Institute for Quantitative Biosciences, University of Tokyo, Tokyo, Japan
| | - Sophie Shaw
- Centre for Genome-Enabled Biology and Medicine, University of Aberdeen, Aberdeen, UK
| | - Kate Rm Clark
- Institute of Medical Sciences, University of Aberdeen, Aberdeen, UK
| | | | - Anne D Donaldson
- Institute of Medical Sciences, University of Aberdeen, Aberdeen, UK
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Nguyen H, Das U, Wang B, Xie J. The matrices and constraints of GT/AG splice sites of more than 1000 species/lineages. Gene 2018; 660:92-101. [PMID: 29588184 DOI: 10.1016/j.gene.2018.03.031] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2017] [Revised: 03/08/2018] [Accepted: 03/12/2018] [Indexed: 12/11/2022]
Abstract
To provide a resource for the splice sites (SS) of different species, we calculated the matrices of nucleotide compositions of about 38 million splice sites from >1000 species/lineages. The matrices are enriched of aGGTAAGT (5'SS) or (Y)6N(C/t)AG(g/a)t (3'SS) overall; however, they are quite diverse among hundreds of species. The diverse matrices remain prominent even under sequence selection pressures, suggesting the existence of diverse constraints as well as U snRNAs and other spliceosomal factors and/or their interactions with the splice sites. Using an algorithm to measure and compare the splice site constraints across all species, we demonstrate their distinct differences quantitatively. As an example of the resource's application to answering specific questions, we confirm that high constraints of particular positions are significantly associated with transcriptome-wide, increased occurrences of alternative splicing when uncommon nucleotides are present. More interestingly, the abundance of alternative splicing in 16 species correlates with the average constraint index of splice sites in a bell curve. This resource will allow users to assess specific sequences/splice sites against the consensus of every Ensembl-annotated species, and to explore the evolutionary changes or relationship to alternative splicing and transcriptome diversity. Web-search or update features are also included.
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Affiliation(s)
- Hai Nguyen
- Department of Physiology & Pathophysiology, Max Rady College of Medicine, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB R3E 0J9, Canada; University of Winnipeg, Winnipeg, MB R3B 2E9, Canada
| | - Urmi Das
- Department of Physiology & Pathophysiology, Max Rady College of Medicine, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB R3E 0J9, Canada
| | - Benjamin Wang
- Department of Physiology & Pathophysiology, Max Rady College of Medicine, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB R3E 0J9, Canada; University of Illinois Urbana-Champaign, IL, USA
| | - Jiuyong Xie
- Department of Physiology & Pathophysiology, Max Rady College of Medicine, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB R3E 0J9, Canada.
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46
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Wilkinson ME, Lin PC, Plaschka C, Nagai K. Cryo-EM Studies of Pre-mRNA Splicing: From Sample Preparation to Model Visualization. Annu Rev Biophys 2018; 47:175-199. [PMID: 29494253 DOI: 10.1146/annurev-biophys-070317-033410] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The removal of noncoding introns from pre-messenger RNA (pre-mRNA) is an essential step in eukaryotic gene expression and is catalyzed by a dynamic multi-megadalton ribonucleoprotein complex called the spliceosome. The spliceosome assembles on pre-mRNA substrates by the stepwise addition of small nuclear ribonucleoprotein particles and numerous protein factors. Extensive remodeling is required to form the RNA-based active site and to mediate the pre-mRNA branching and ligation reactions. In the past two years, cryo-electron microscopy (cryo-EM) structures of spliceosomes captured in different assembly and catalytic states have greatly advanced our understanding of its mechanism. This was made possible by long-standing efforts in the purification of spliceosome intermediates as well as recent developments in cryo-EM imaging and computational methodology. The resulting high-resolution densities allow for de novo model building in core regions of the complexes. In peripheral and less ordered regions, the combination of cross-linking, bioinformatics, biochemical, and genetic data is essential for accurate modeling. Here, we summarize these achievements and highlight the critical steps in obtaining near-atomic resolution structures of the spliceosome.
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Affiliation(s)
- Max E Wilkinson
- MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, United Kingdom; , , ,
| | - Pei-Chun Lin
- MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, United Kingdom; , , ,
| | - Clemens Plaschka
- MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, United Kingdom; , , ,
| | - Kiyoshi Nagai
- MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, United Kingdom; , , ,
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47
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Long H, Behringer MG, Williams E, Te R, Lynch M. Similar Mutation Rates but Highly Diverse Mutation Spectra in Ascomycete and Basidiomycete Yeasts. Genome Biol Evol 2018; 8:3815-3821. [PMID: 28173099 PMCID: PMC5521736 DOI: 10.1093/gbe/evw286] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/23/2016] [Indexed: 12/21/2022] Open
Abstract
Yeast species are extremely diverse and not monophyletic. Because the majority of yeast research focuses on ascomycetes, the mutational determinants of genetic diversity across yeast species are not well understood. By combining mutation-accumulation techniques with whole-genome sequencing, we resolved the genomic mutation rate and spectrum of the oleaginous (oil-producing) ‘red yeast’ Rhodotorula toruloides, the first such study in the fungal phylum Basidiomycota. We find that the mutation spectrum is quite different from what has been observed in all other studied unicellular eukaryotes, but similar to that in most bacteria—a predominance of transitions relative to transversions. Rhodotorula toruloides has a significantly higher A:T→G:C transition rate—possibly elevated by the abundant flanking G/C nucleotides in the GC-rich genome, as well as a much lower G:C→T:A transversion rate. In spite of these striking differences, there are substantial consistencies between R. toruloides and the ascomycete model yeasts: a spontaneous base-substitution mutation rate of 1.90 × 10 −10 per site per cell division as well as an elevated mutation rate at non-methylated 5'CpG3' sites. These results imply the evolution of variable mutation spectra in the face of similar mutation rates in yeasts.
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Affiliation(s)
- Hongan Long
- Department of Biology, Indiana University, Bloomington, IN, USA
| | | | - Emily Williams
- Department of Biology, Indiana University, Bloomington, IN, USA
| | - Ronald Te
- Department of Biology, Indiana University, Bloomington, IN, USA
| | - Michael Lynch
- Department of Biology, Indiana University, Bloomington, IN, USA
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48
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Abrhámová K, Nemčko F, Libus J, Převorovský M, Hálová M, Půta F, Folk P. Introns provide a platform for intergenic regulatory feedback of RPL22 paralogs in yeast. PLoS One 2018; 13:e0190685. [PMID: 29304067 PMCID: PMC5755908 DOI: 10.1371/journal.pone.0190685] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2017] [Accepted: 12/19/2017] [Indexed: 01/04/2023] Open
Abstract
Ribosomal protein genes (RPGs) in Saccharomyces cerevisiae are a remarkable regulatory group that may serve as a model for understanding genetic redundancy in evolutionary adaptations. Most RPGs exist as pairs of highly conserved functional paralogs with divergent untranslated regions and introns. We examined the roles of introns in strains with various combinations of intron and gene deletions in RPL22, RPL2, RPL16, RPL37, RPL17, RPS0, and RPS18 paralog pairs. We found that introns inhibited the expression of their genes in the RPL22 pair, with the RPL22B intron conferring a much stronger effect. While the WT RPL22A/RPL22B mRNA ratio was 93/7, the rpl22aΔi/RPL22B and RPL22A/rpl22bΔi ratios were >99/<1 and 60/40, respectively. The intron in RPL2A stimulated the expression of its own gene, but the removal of the other introns had little effect on expression of the corresponding gene pair. Rpl22 protein abundances corresponded to changes in mRNAs. Using splicing reporters containing endogenous intron sequences, we demonstrated that these effects were due to the inhibition of splicing by Rpl22 proteins but not by their RNA-binding mutant versions. Indeed, only WT Rpl22A/Rpl22B proteins (but not the mutants) interacted in a yeast three-hybrid system with an RPL22B intronic region between bp 165 and 236. Transcriptome analysis showed that both the total level of Rpl22 and the A/B ratio were important for maintaining the WT phenotype. The data presented here support the contention that the Rpl22B protein has a paralog-specific role. The RPL22 singleton of Kluyveromyces lactis, which did not undergo whole genome duplication, also responded to Rpl22-mediated inhibition in K. lactis cells. Vice versa, the overproduction of the K. lactis protein reduced the expression of RPL22A/B in S. cerevisiae. The extraribosomal function of of the K. lactis Rpl22 suggests that the loop regulating RPL22 paralogs of S. cerevisiae evolved from autoregulation.
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Affiliation(s)
- Kateřina Abrhámová
- Department of Cell Biology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Filip Nemčko
- Department of Cell Biology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Jiří Libus
- Department of Cell Biology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Martin Převorovský
- Department of Cell Biology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Martina Hálová
- Department of Cell Biology, Faculty of Science, Charles University, Prague, Czech Republic
| | - František Půta
- Department of Cell Biology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Petr Folk
- Department of Cell Biology, Faculty of Science, Charles University, Prague, Czech Republic
- * E-mail:
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49
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Wilkinson ME, Fica SM, Galej WP, Norman CM, Newman AJ, Nagai K. Postcatalytic spliceosome structure reveals mechanism of 3'-splice site selection. Science 2017; 358:1283-1288. [PMID: 29146871 DOI: 10.1126/science.aar3729] [Citation(s) in RCA: 78] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Accepted: 11/09/2017] [Indexed: 12/27/2022]
Abstract
Introns are removed from eukaryotic messenger RNA precursors by the spliceosome in two transesterification reactions-branching and exon ligation. The mechanism of 3'-splice site recognition during exon ligation has remained unclear. Here we present the 3.7-angstrom cryo-electron microscopy structure of the yeast P-complex spliceosome immediately after exon ligation. The 3'-splice site AG dinucleotide is recognized through non-Watson-Crick pairing with the 5' splice site and the branch-point adenosine. After the branching reaction, protein factors work together to remodel the spliceosome and stabilize a conformation competent for 3'-splice site docking, thereby promoting exon ligation. The structure accounts for the strict conservation of the GU and AG dinucleotides at the 5' and 3' ends of introns and provides insight into the catalytic mechanism of exon ligation.
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Affiliation(s)
- Max E Wilkinson
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK.
| | - Sebastian M Fica
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | | | | | | | - Kiyoshi Nagai
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK.
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50
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Machné R, Murray DB, Stadler PF. Similarity-Based Segmentation of Multi-Dimensional Signals. Sci Rep 2017; 7:12355. [PMID: 28955039 PMCID: PMC5617875 DOI: 10.1038/s41598-017-12401-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2017] [Accepted: 08/30/2017] [Indexed: 11/25/2022] Open
Abstract
The segmentation of time series and genomic data is a common problem in computational biology. With increasingly complex measurement procedures individual data points are often not just numbers or simple vectors in which all components are of the same kind. Analysis methods that capitalize on slopes in a single real-valued data track or that make explicit use of the vectorial nature of the data are not applicable in such scenaria. We develop here a framework for segmentation in arbitrary data domains that only requires a minimal notion of similarity. Using unsupervised clustering of (a sample of) the input yields an approximate segmentation algorithm that is efficient enough for genome-wide applications. As a showcase application we segment a time-series of transcriptome sequencing data from budding yeast, in high temporal resolution over ca. 2.5 cycles of the short-period respiratory oscillation. The algorithm is used with a similarity measure focussing on periodic expression profiles across the metabolic cycle rather than coverage per time point.
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Affiliation(s)
- Rainer Machné
- Institute for Synthetic Microbiology, Cluster of Excellence on Plant Sciences (CEPLAS), Heinrich Heine University Düsseldorf, Universitätsstraße 1, D-40225, Düsseldorf, Germany. .,Department of Theoretical Chemistry of the University of Vienna, Währingerstrasse 17, Vienna, A-1090, Austria.
| | - Douglas B Murray
- Institute for Advanced Biosciences, Keio University, Tsuruoka, Yamagata, 997-0017, Japan
| | - Peter F Stadler
- Bioinformatics Group, Department of Computer Science, Interdisciplinary Center for Bioinformatics, German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Competence Center for Scalable Data Services and Solutions, and Leipzig Research Center for Civilization Diseases, University Leipzig, Härtelstrasse 16-18, D-04107, Leipzig, Germany. .,Max Planck Institute for Mathematics in the Sciences, Inselstraße 22, D-04103, Leipzig, Germany. .,Fraunhofer Institute for Cell Therapy and Immunology, Perlickstrasse 1, D-04103, Leipzig, Germany. .,Department of Theoretical Chemistry of the University of Vienna, Währingerstrasse 17, Vienna, A-1090, Austria. .,Center for RNA in Technology and Health, Univ. Copenhagen, Grønneg ardsvej 3, Frederiksberg C, Denmark. .,Santa Fe Institute, 1399 Hyde Park Road, Santa Fe, NM, 87501, USA.
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