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Balan T, Lerner LK, Holoch D, Duharcourt S. Small-RNA-guided histone modifications and somatic genome elimination in ciliates. WILEY INTERDISCIPLINARY REVIEWS. RNA 2024; 15:e1848. [PMID: 38605483 DOI: 10.1002/wrna.1848] [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: 01/25/2024] [Revised: 03/22/2024] [Accepted: 03/22/2024] [Indexed: 04/13/2024]
Abstract
Transposable elements and other repeats are repressed by small-RNA-guided histone modifications in fungi, plants and animals. The specificity of silencing is achieved through base-pairing of small RNAs corresponding to the these genomic loci to nascent noncoding RNAs, which allows the recruitment of histone methyltransferases that methylate histone H3 on lysine 9. Self-reinforcing feedback loops enhance small RNA production and ensure robust and heritable repression. In the unicellular ciliate Paramecium tetraurelia, small-RNA-guided histone modifications lead to the elimination of transposable elements and their remnants, a definitive form of repression. In this organism, germline and somatic functions are separated within two types of nuclei with different genomes. At each sexual cycle, development of the somatic genome is accompanied by the reproducible removal of approximately a third of the germline genome. Instead of recruiting a H3K9 methyltransferase, small RNAs corresponding to eliminated sequences tether Polycomb Repressive Complex 2, which in ciliates has the unique property of catalyzing both lysine 9 and lysine 27 trimethylation of histone H3. These histone modifications that are crucial for the elimination of transposable elements are thought to guide the endonuclease complex, which triggers double-strand breaks at these specific genomic loci. The comparison between ciliates and other eukaryotes underscores the importance of investigating small-RNAs-directed chromatin silencing in a diverse range of organisms. This article is categorized under: Regulatory RNAs/RNAi/Riboswitches > RNAi: Mechanisms of Action.
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Affiliation(s)
- Thomas Balan
- Université Paris Cité, CNRS, Institut Jacques Monod, Paris, France
| | | | - Daniel Holoch
- Université Paris Cité, CNRS, Institut Jacques Monod, Paris, France
- Institut Curie, INSERM U934/CNRS UMR 3215, Paris Sciences et Lettres Research University, Sorbonne University, Paris, France
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Kim J, Park MJ, Shim D, Ryoo R. De novo genome assembly of the bioluminescent mushroom Omphalotus guepiniiformis reveals an Omphalotus-specific lineage of the luciferase gene block. Genomics 2022; 114:110514. [PMID: 36332840 DOI: 10.1016/j.ygeno.2022.110514] [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: 07/07/2022] [Revised: 10/04/2022] [Accepted: 10/23/2022] [Indexed: 11/05/2022]
Abstract
Omphalotus guepiniiformis, a bioluminescent mushroom species, is a source of the potentially valuable anticancer chemical. To provide genome information, we de novo assembled the high-quality O. guepiniiformis genome using two Next-Generation sequencing techniques, PacBio and Illumina sequencing. Our draft O. guepiniiformis genome comprises 42.5 Mbp of sequence with only 80 contigs and an N50 sequence length of over 1 Mbp. There were 15,554 predicted coding genes, and 7693 genes were functionally annotated with Gene Ontology terms. We performed a genomic study focusing on mushroom bioluminescent pathway cluster genes by comparing 17 luminescent and 23 non-luminescent Agaricales species belonging to 23 genera. Synteny analysis of genomic regions near the luminescent pathway cluster genes inferred that the Omphalotus lineage was genus-specific. In summary, our de novo assembled O. guepiniiformis genome provides significant biological insights into this organism, including the evolution of the luciferase gene block, and forms the basis for future analyses.
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Affiliation(s)
- Jaewook Kim
- Department of Biological Sciences, Chungnam National University, 34134 Daejeon, Republic of Korea
| | - Mi-Jeong Park
- Forest Microbiology Division, Department of Forest Bio-Resources, National Institute of Forest Science, 16631 Suwon, Republic of Korea
| | - Donghwan Shim
- Department of Biological Sciences, Chungnam National University, 34134 Daejeon, Republic of Korea.
| | - Rhim Ryoo
- Forest Microbiology Division, Department of Forest Bio-Resources, National Institute of Forest Science, 16631 Suwon, Republic of Korea.
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Functional Characterization of the N-Terminal Disordered Region of the piggyBac Transposase. Int J Mol Sci 2022; 23:ijms231810317. [PMID: 36142241 PMCID: PMC9499001 DOI: 10.3390/ijms231810317] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Revised: 08/22/2022] [Accepted: 09/03/2022] [Indexed: 01/15/2023] Open
Abstract
The piggyBac DNA transposon is an active element initially isolated from the cabbage looper moth, but members of this superfamily are also present in most eukaryotic evolutionary lineages. The functionally important regions of the transposase are well described. There is an RNase H-like fold containing the DDD motif responsible for the catalytic DNA cleavage and joining reactions and a C-terminal cysteine-rich domain important for interaction with the transposon DNA. However, the protein also contains a ~100 amino acid long N-terminal disordered region (NTDR) whose function is currently unknown. Here we show that deletion of the NTDR significantly impairs piggyBac transposition, although the extent of decrease is strongly cell-type specific. Moreover, replacing the NTDR with scrambled but similarly disordered sequences did not rescue transposase activity, indicating the importance of sequence conservation. Cell-based transposon excision and integration assays reveal that the excision step is more severely affected by NTDR deletion. Finally, bioinformatic analyses indicated that the NTDR is specific for the piggyBac superfamily and is also present in domesticated, transposase-derived proteins incapable of catalyzing transposition. Our results indicate an essential role of the NTDR in the “fine-tuning” of transposition and its significance in the functions of piggyBac-originated co-opted genes.
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Raskó T, Pande A, Radscheit K, Zink A, Singh M, Sommer C, Wachtl G, Kolacsek O, Inak G, Szvetnik A, Petrakis S, Bunse M, Bansal V, Selbach M, Orbán TI, Prigione A, Hurst LD, Izsvák Z. A Novel Gene Controls a New Structure: PiggyBac Transposable Element-Derived 1, Unique to Mammals, Controls Mammal-Specific Neuronal Paraspeckles. Mol Biol Evol 2022; 39:6661922. [PMID: 36205081 PMCID: PMC9538788 DOI: 10.1093/molbev/msac175] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Although new genes can arrive from modes other than duplication, few examples are well characterized. Given high expression in some human brain subregions and a putative link to psychological disorders [e.g., schizophrenia (SCZ)], suggestive of brain functionality, here we characterize piggyBac transposable element-derived 1 (PGBD1). PGBD1 is nonmonotreme mammal-specific and under purifying selection, consistent with functionality. The gene body of human PGBD1 retains much of the original DNA transposon but has additionally captured SCAN and KRAB domains. Despite gene body retention, PGBD1 has lost transposition abilities, thus transposase functionality is absent. PGBD1 no longer recognizes piggyBac transposon-like inverted repeats, nonetheless PGBD1 has DNA binding activity. Genome scale analysis identifies enrichment of binding sites in and around genes involved in neuronal development, with association with both histone activating and repressing marks. We focus on one of the repressed genes, the long noncoding RNA NEAT1, also dysregulated in SCZ, the core structural RNA of paraspeckles. DNA binding assays confirm specific binding of PGBD1 both in the NEAT1 promoter and in the gene body. Depletion of PGBD1 in neuronal progenitor cells (NPCs) results in increased NEAT1/paraspeckles and differentiation. We conclude that PGBD1 has evolved core regulatory functionality for the maintenance of NPCs. As paraspeckles are a mammal-specific structure, the results presented here show a rare example of the evolution of a novel gene coupled to the evolution of a contemporaneous new structure.
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Affiliation(s)
- Tamás Raskó
- Max Delbrück Center for Molecular Medicine in the Helmholtz Society, Berlin, Germany
| | | | | | - Annika Zink
- Department of General Pediatrics, Neonatology and Pediatric Cardiology, Medical Faculty, Heinrich Heine University, Duesseldorf, Germany
| | - Manvendra Singh
- Max Delbrück Center for Molecular Medicine in the Helmholtz Society, Berlin, Germany
| | - Christian Sommer
- Max Delbrück Center for Molecular Medicine in the Helmholtz Society, Berlin, Germany
| | - Gerda Wachtl
- Institute of Enzymology, Research Centre for Natural Sciences, ELKH, Budapest, Hungary,Doctoral School of Biology, Institute of Biology, ELTE Eötvös Loránd University, Budapest, Hungary
| | - Orsolya Kolacsek
- Institute of Enzymology, Research Centre for Natural Sciences, ELKH, Budapest, Hungary
| | - Gizem Inak
- Department of General Pediatrics, Neonatology and Pediatric Cardiology, Medical Faculty, Heinrich Heine University, Duesseldorf, Germany
| | - Attila Szvetnik
- Max Delbrück Center for Molecular Medicine in the Helmholtz Society, Berlin, Germany
| | - Spyros Petrakis
- Institute of Applied Biosciences/Centre for Research and Technology Hellas, 57001 Thessaloniki, Greece
| | - Mario Bunse
- Max Delbrück Center for Molecular Medicine in the Helmholtz Society, Berlin, Germany
| | - Vikas Bansal
- Biomedical Data Science and Machine Learning Group, German Center for Neurodegenerative Diseases, Tübingen 72076, Germany
| | - Matthias Selbach
- Max Delbrück Center for Molecular Medicine in the Helmholtz Society, Berlin, Germany
| | - Tamás I Orbán
- Institute of Enzymology, Research Centre for Natural Sciences, ELKH, Budapest, Hungary
| | - Alessandro Prigione
- Department of General Pediatrics, Neonatology and Pediatric Cardiology, Medical Faculty, Heinrich Heine University, Duesseldorf, Germany
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Unravelling the Structure of the Tetrahedral Metal-Binding Site in METP3 through an Experimental and Computational Approach. Molecules 2021; 26:molecules26175221. [PMID: 34500655 PMCID: PMC8434281 DOI: 10.3390/molecules26175221] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Revised: 08/25/2021] [Accepted: 08/26/2021] [Indexed: 11/17/2022] Open
Abstract
Understanding the structural determinants for metal ion coordination in metalloproteins is a fundamental issue for designing metal binding sites with predetermined geometry and activity. In order to achieve this, we report in this paper the design, synthesis and metal binding properties of METP3, a homodimer made up of a small peptide, which self assembles in the presence of tetrahedrally coordinating metal ions. METP3 was obtained through a redesign approach, starting from the previously developed METP molecule. The undecapeptide sequence of METP, which dimerizes to house a Cys4 tetrahedral binding site, was redesigned in order to accommodate a Cys2His2 site. The binding properties of METP3 were determined toward different metal ions. Successful assembly of METP3 with Co(II), Zn(II) and Cd(II), in the expected 2:1 stoichiometry and tetrahedral geometry was proven by UV-visible spectroscopy. CD measurements on both the free and metal-bound forms revealed that the metal coordination drives the peptide chain to fold into a turned conformation. Finally, NMR data of the Zn(II)-METP3 complex, together with a retrostructural analysis of the Cys-X-X-His motif in metalloproteins, allowed us to define the model structure. All the results establish the suitability of the short METP sequence for accommodating tetrahedral metal binding sites, regardless of the first coordination ligands.
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