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Tournayre J, Polonais V, Wawrzyniak I, Akossi RF, Parisot N, Lerat E, Delbac F, Souvignet P, Reichstadt M, Peyretaillade E. MicroAnnot: A Dedicated Workflow for Accurate Microsporidian Genome Annotation. Int J Mol Sci 2024; 25:880. [PMID: 38255958 PMCID: PMC10815200 DOI: 10.3390/ijms25020880] [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: 10/27/2023] [Revised: 12/29/2023] [Accepted: 01/04/2024] [Indexed: 01/24/2024] Open
Abstract
With nearly 1700 species, Microsporidia represent a group of obligate intracellular eukaryotes with veterinary, economic and medical impacts. To help understand the biological functions of these microorganisms, complete genome sequencing is routinely used. Nevertheless, the proper prediction of their gene catalogue is challenging due to their taxon-specific evolutionary features. As innovative genome annotation strategies are needed to obtain a representative snapshot of the overall lifestyle of these parasites, the MicroAnnot tool, a dedicated workflow for microsporidian sequence annotation using data from curated databases of accurately annotated microsporidian genes, has been developed. Furthermore, specific modules have been implemented to perform small gene (<300 bp) and transposable element identification. Finally, functional annotation was performed using the signature-based InterProScan software. MicroAnnot's accuracy has been verified by the re-annotation of four microsporidian genomes for which structural annotation had previously been validated. With its comparative approach and transcriptional signal identification method, MicroAnnot provides an accurate prediction of translation initiation sites, an efficient identification of transposable elements, as well as high specificity and sensitivity for microsporidian genes, including those under 300 bp.
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Affiliation(s)
- Jérémy Tournayre
- INRAE, UMR Herbivores, Université Clermont Auvergne, VetAgro Sup, 63122 Saint-Genès-Champanelle, France; (J.T.); (P.S.); (M.R.)
| | - Valérie Polonais
- LMGE, CNRS, Université Clermont Auvergne, 63000 Clermont-Ferrand, France; (V.P.); (I.W.); (R.F.A.); (F.D.)
| | - Ivan Wawrzyniak
- LMGE, CNRS, Université Clermont Auvergne, 63000 Clermont-Ferrand, France; (V.P.); (I.W.); (R.F.A.); (F.D.)
| | - Reginald Florian Akossi
- LMGE, CNRS, Université Clermont Auvergne, 63000 Clermont-Ferrand, France; (V.P.); (I.W.); (R.F.A.); (F.D.)
| | - Nicolas Parisot
- UMR 203, BF2I, INRAE, INSA Lyon, Université de Lyon, 69621 Villeurbanne, France
| | - Emmanuelle Lerat
- VAS, CNRS, UMR5558, LBBE, Université Claude Bernard Lyon 1, 69622 Villeurbanne, France;
| | - Frédéric Delbac
- LMGE, CNRS, Université Clermont Auvergne, 63000 Clermont-Ferrand, France; (V.P.); (I.W.); (R.F.A.); (F.D.)
| | - Pierre Souvignet
- INRAE, UMR Herbivores, Université Clermont Auvergne, VetAgro Sup, 63122 Saint-Genès-Champanelle, France; (J.T.); (P.S.); (M.R.)
| | - Matthieu Reichstadt
- INRAE, UMR Herbivores, Université Clermont Auvergne, VetAgro Sup, 63122 Saint-Genès-Champanelle, France; (J.T.); (P.S.); (M.R.)
| | - Eric Peyretaillade
- LMGE, CNRS, Université Clermont Auvergne, 63000 Clermont-Ferrand, France; (V.P.); (I.W.); (R.F.A.); (F.D.)
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Whelan TA, Fast NM. Exploring the highly reduced spliceosome of Pseudoloma neurophilia. Curr Biol 2023; 33:R1280-R1281. [PMID: 38113835 DOI: 10.1016/j.cub.2023.10.034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Revised: 10/18/2023] [Accepted: 10/19/2023] [Indexed: 12/21/2023]
Abstract
Spliceosomal introns evolved early in eukaryogenesis, originating from self-splicing group II introns that invaded the proto-eukaryotic genome1. Elements of these ribozymes, now called snRNAs (U1, U2, U4, U5, U6), were co-opted to excise these invasive elements. Prior to eukaryotic diversification, the spliceosome is predicted to have accumulated hundreds of proteins2. This early complexification has obscured our understanding of spliceosomal evolution. Reduced systems with few introns and tiny spliceosomes give insights into the plasticity of the splicing reaction and provide an opportunity to study the evolution of the spliceosome3,4. Microsporidia are intracellular parasites possessing extremely reduced genomes that have lost many, and in some instances all, introns5. In the purportedly intron-lacking genome of the microsporidian Pseudoloma neurophilia6, we identified two introns that are spliced at high levels. Furthermore, with only 14 predicted proteins, the P. neurophilia spliceosome could be the smallest known. Intriguingly, the few proteins retained are divergent compared to canonical orthologs. Even the central spliceosomal protein Prp8, which originated from the proteinaceous component of group II introns, is extremely divergent. This is unusual given that Prp8 is highly conserved across eukaryotes, including other microsporidia. All five P. neurophilia snRNAs are present, and all but U2 have diverged extensively, likely resulting from the loss of interacting proteins. Despite this divergence, U1 and U2 are predicted to pair with intron sequences more extensively than previously described. The P. neurophilia spliceosome is retained to splice a mere two introns and, with few proteins and reliance on RNA-RNA interactions, could function in a manner more reminiscent of presumed ancestral splicing.
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Affiliation(s)
- Thomas A Whelan
- Biodiversity Research Centre, Department of Botany, University of British Columbia, Vancouver BC V6T 1Z4, Canada
| | - Naomi M Fast
- Biodiversity Research Centre, Department of Botany, University of British Columbia, Vancouver BC V6T 1Z4, Canada.
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Angst P, Pombert JF, Ebert D, Fields PD. Near chromosome-level genome assembly of the microsporidium Hamiltosporidium tvaerminnensis. G3 (BETHESDA, MD.) 2023; 13:jkad185. [PMID: 37565496 PMCID: PMC10542269 DOI: 10.1093/g3journal/jkad185] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2023] [Accepted: 08/05/2023] [Indexed: 08/12/2023]
Abstract
Microsporidia are intracellular parasitic fungi whose genomes rank among the smallest of all known eukaryotes. A number of outstanding questions remain concerning the evolution of their large-scale variation in genome architecture, responsible for genome size variation of more than an order of magnitude. This genome report presents the first near-chromosomal assembly of a large-genome microsporidium, Hamiltosporidium tvaerminnensis. Combined Oxford Nanopore, Pacific Biosciences (PacBio), and Illumina sequencing led to a genome assembly of 17 contigs, 11 of which represent complete chromosomes. Our assembly is 21.64 Mb in length, has an N50 of 1.44 Mb, and consists of 39.56% interspersed repeats. We introduce a novel approach in microsporidia, PacBio Iso-Seq, as part of a larger annotation pipeline for obtaining high-quality annotations of 3,573 protein-coding genes. Based on direct evidence from the full-length Iso-Seq transcripts, we present evidence for alternative polyadenylation and variation in splicing efficiency, which are potential regulation mechanisms for gene expression in microsporidia. The generated high-quality genome assembly is a necessary resource for comparative genomics that will help elucidate the evolution of genome architecture in response to intracellular parasitism.
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Affiliation(s)
- Pascal Angst
- Department of Environmental Sciences, Zoology, University of Basel, Basel 4051, Switzerland
| | | | - Dieter Ebert
- Department of Environmental Sciences, Zoology, University of Basel, Basel 4051, Switzerland
| | - Peter D Fields
- Department of Environmental Sciences, Zoology, University of Basel, Basel 4051, Switzerland
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Whelan TA, Fast NM. Microsporidia. Curr Biol 2023; 33:R936-R938. [PMID: 37751700 DOI: 10.1016/j.cub.2023.06.076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/28/2023]
Abstract
In this Quick guide, Thomas Whelan and Naomi Fast introduce the microsporidia: obligate intracellular parasites with the most extremely reduced genomes known in eukaryotes.
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Affiliation(s)
- Thomas A Whelan
- Biodiversity Research Centre, Department of Botany, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - Naomi M Fast
- Biodiversity Research Centre, Department of Botany, University of British Columbia, Vancouver, BC V6T 1Z4, Canada.
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5
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Žárský V, Karnkowska A, Boscaro V, Trznadel M, Whelan TA, Hiltunen-Thorén M, Onut-Brännström I, Abbott CL, Fast NM, Burki F, Keeling PJ. Contrasting outcomes of genome reduction in mikrocytids and microsporidians. BMC Biol 2023; 21:137. [PMID: 37280585 DOI: 10.1186/s12915-023-01635-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Accepted: 05/26/2023] [Indexed: 06/08/2023] Open
Abstract
BACKGROUND Intracellular symbionts often undergo genome reduction, losing both coding and non-coding DNA in a process that ultimately produces small, gene-dense genomes with few genes. Among eukaryotes, an extreme example is found in microsporidians, which are anaerobic, obligate intracellular parasites related to fungi that have the smallest nuclear genomes known (except for the relic nucleomorphs of some secondary plastids). Mikrocytids are superficially similar to microsporidians: they are also small, reduced, obligate parasites; however, as they belong to a very different branch of the tree of eukaryotes, the rhizarians, such similarities must have evolved in parallel. Since little genomic data are available from mikrocytids, we assembled a draft genome of the type species, Mikrocytos mackini, and compared the genomic architecture and content of microsporidians and mikrocytids to identify common characteristics of reduction and possible convergent evolution. RESULTS At the coarsest level, the genome of M. mackini does not exhibit signs of extreme genome reduction; at 49.7 Mbp with 14,372 genes, the assembly is much larger and gene-rich than those of microsporidians. However, much of the genomic sequence and most (8075) of the protein-coding genes code for transposons, and may not contribute much of functional relevance to the parasite. Indeed, the energy and carbon metabolism of M. mackini share several similarities with those of microsporidians. Overall, the predicted proteome involved in cellular functions is quite reduced and gene sequences are extremely divergent. Microsporidians and mikrocytids also share highly reduced spliceosomes that have retained a strikingly similar subset of proteins despite having reduced independently. In contrast, the spliceosomal introns in mikrocytids are very different from those of microsporidians in that they are numerous, conserved in sequence, and constrained to an exceptionally narrow size range (all 16 or 17 nucleotides long) at the shortest extreme of known intron lengths. CONCLUSIONS Nuclear genome reduction has taken place many times and has proceeded along different routes in different lineages. Mikrocytids show a mix of similarities and differences with other extreme cases, including uncoupling the actual size of a genome with its functional reduction.
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Affiliation(s)
- Vojtečh Žárský
- Department of Botany, University of British Columbia, V6T 1Z4, Vancouver, 3529-6270 University Boulevard, BC, Canada
| | - Anna Karnkowska
- Department of Botany, University of British Columbia, V6T 1Z4, Vancouver, 3529-6270 University Boulevard, BC, Canada
- Institute of Evolutionary Biology, Faculty of Biology, University of Warsaw, 02-089, Warsaw, Poland
| | - Vittorio Boscaro
- Department of Botany, University of British Columbia, V6T 1Z4, Vancouver, 3529-6270 University Boulevard, BC, Canada.
| | - Morelia Trznadel
- Department of Botany, University of British Columbia, V6T 1Z4, Vancouver, 3529-6270 University Boulevard, BC, Canada
| | - Thomas A Whelan
- Department of Botany, University of British Columbia, V6T 1Z4, Vancouver, 3529-6270 University Boulevard, BC, Canada
| | - Markus Hiltunen-Thorén
- Department of Organismal Biology, Uppsala University, Norbyv. 18D, 752 36, Uppsala, Sweden
- Department of Ecology, Environment and Plant Sciences, Stockholm University, SE-106 91, Stockholm, Sweden
| | - Ioana Onut-Brännström
- Department of Organismal Biology, Uppsala University, Norbyv. 18D, 752 36, Uppsala, Sweden
- Department of Ecology and Genetics, Uppsala University, 752 36, Uppsala, Sweden
- Natural History Museum, University of Oslo, 0562, Oslo, Norway
| | - Cathryn L Abbott
- Pacific Biological Station, Fisheries and Oceans Canada, Nanaimo, BC, V9T 6N7, Canada
| | - Naomi M Fast
- Department of Botany, University of British Columbia, V6T 1Z4, Vancouver, 3529-6270 University Boulevard, BC, Canada
| | - Fabien Burki
- Department of Organismal Biology, Uppsala University, Norbyv. 18D, 752 36, Uppsala, Sweden
| | - Patrick J Keeling
- Department of Botany, University of British Columbia, V6T 1Z4, Vancouver, 3529-6270 University Boulevard, BC, Canada.
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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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7
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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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8
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Williams BAP, Williams TA, Trew J. Comparative Genomics of Microsporidia. EXPERIENTIA SUPPLEMENTUM (2012) 2022; 114:43-69. [PMID: 35543998 DOI: 10.1007/978-3-030-93306-7_2] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
The microsporidia are a phylum of intracellular parasites that represent the eukaryotic cell in a state of extreme reduction, with genomes and metabolic capabilities embodying eukaryotic cells in arguably their most streamlined state. Over the past 20 years, microsporidian genomics has become a rapidly expanding field starting with sequencing of the genome of Encephalitozoon cuniculi, one of the first ever sequenced eukaryotes, to the current situation where we have access to the data from over 30 genomes across 20+ genera. Reaching back further in evolutionary history, to the point where microsporidia diverged from other eukaryotic lineages, we now also have genomic data for some of the closest known relatives of the microsporidia such as Rozella allomycis, Metchnikovella spp. and Amphiamblys sp. Data for these organisms allow us to better understand the genomic processes that shaped the emergence of the microsporidia as a group. These intensive genomic efforts have revealed some of the processes that have shaped microsporidian cells and genomes including patterns of genome expansions and contractions through gene gain and loss, whole genome duplication, differential patterns of invasion and purging of transposable elements. All these processes have been shown to occur across short and longer time scales to give rise to a phylum of parasites with dynamic genomes with a diversity of sizes and organisations.
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Affiliation(s)
| | - Tom A Williams
- School of Biological Sciences, University of Bristol, Bristol, UK
| | - Jahcub Trew
- School of Biosciences, University of Exeter, Exeter, UK
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9
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Lim CS, Weinstein BN, Roy SW, Brown CM. Analysis of fungal genomes reveals commonalities of intron gain or loss and functions in intron-poor species. Mol Biol Evol 2021; 38:4166-4186. [PMID: 33772558 PMCID: PMC8476143 DOI: 10.1093/molbev/msab094] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Previous evolutionary reconstructions have concluded that early eukaryotic ancestors including both the last common ancestor of eukaryotes and of all fungi had intron-rich genomes. By contrast, some extant eukaryotes have few introns, underscoring the complex histories of intron–exon structures, and raising the question as to why these few introns are retained. Here, we have used recently available fungal genomes to address a variety of questions related to intron evolution. Evolutionary reconstruction of intron presence and absence using 263 diverse fungal species supports the idea that massive intron reduction through intron loss has occurred in multiple clades. The intron densities estimated in various fungal ancestors differ from zero to 7.6 introns per 1 kb of protein-coding sequence. Massive intron loss has occurred not only in microsporidian parasites and saccharomycetous yeasts, but also in diverse smuts and allies. To investigate the roles of the remaining introns in highly-reduced species, we have searched for their special characteristics in eight intron-poor fungi. Notably, the introns of ribosome-associated genes RPL7 and NOG2 have conserved positions; both intron-containing genes encoding snoRNAs. Furthermore, both the proteins and snoRNAs are involved in ribosome biogenesis, suggesting that the expression of the protein-coding genes and noncoding snoRNAs may be functionally coordinated. Indeed, these introns are also conserved in three-quarters of fungi species. Our study shows that fungal introns have a complex evolutionary history and underappreciated roles in gene expression.
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Affiliation(s)
- Chun Shen Lim
- Department of Biochemistry, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Brooke N Weinstein
- Quantitative & Systems Biology, School of Natural Sciences, University of California-Merced, Merced, CA, USA.,Department of Biology, San Francisco State University, San Francisco, CA, USA
| | - Scott W Roy
- Quantitative & Systems Biology, School of Natural Sciences, University of California-Merced, Merced, CA, USA.,Department of Biology, San Francisco State University, San Francisco, CA, USA
| | - Chris M Brown
- Department of Biochemistry, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
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10
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Wong DK, Stark MS, Rader SD, Fast NM. Characterization of Pre-mRNA Splicing and Spliceosomal Machinery in Porphyridium purpureum and Evolutionary Implications for Red Algae. J Eukaryot Microbiol 2021; 68:e12844. [PMID: 33569840 DOI: 10.1111/jeu.12844] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Revised: 01/28/2021] [Accepted: 02/05/2021] [Indexed: 11/29/2022]
Abstract
Pre-mRNA splicing is a highly conserved eukaryotic process, but our understanding of it is limited by a historical focus on well-studied organisms such as humans and yeast. There is considerable diversity in mechanisms and components of pre-mRNA splicing, especially in lineages that have evolved under the pressures of genome reduction. The ancestor of red algae is thought to have undergone genome reduction prior to the lineage's radiation, resulting in overall gene and intron loss in extant groups. Previous studies on the extremophilic red alga Cyanidioschyzon merolae revealed an intron-sparse genome with a highly reduced spliceosome. To determine whether these features applied to other red algae, we investigated multiple aspects of pre-mRNA splicing in the mesophilic red alga Porphyridium purpureum. Through strand-specific RNA-Seq, we observed high levels of intron retention across a large number of its introns, and nearly half of the transcripts for these genes are not spliced at all. We also discovered a relationship between variability of 5' splice site sequences and levels of splicing. To further investigate the connections between intron retention and splicing machinery, we bioinformatically assembled the P. purpureum spliceosome, and biochemically verified the presence of snRNAs. While most other core spliceosomal components are present, our results suggest highly divergent or missing U1 snRNP proteins, despite the presence of an uncharacteristically long U1 snRNA. These unusual aspects highlight the diverse nature of pre-mRNA splicing that can be seen in lesser-studied eukaryotes, raising the importance of investigating fundamental eukaryotic processes outside of model organisms.
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Affiliation(s)
- Donald K Wong
- Department of Botany, University of British Columbia, 3156-6270 University Boulevard, Vancouver, BC, Canada
| | - Martha S Stark
- Department of Chemistry, University of Northern British Columbia, 3333 University Way, Prince George, BC, Canada
| | - Stephen D Rader
- Department of Chemistry, University of Northern British Columbia, 3333 University Way, Prince George, BC, Canada
| | - Naomi M Fast
- Department of Botany, University of British Columbia, 3156-6270 University Boulevard, Vancouver, BC, Canada
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11
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Petibon C, Malik Ghulam M, Catala M, Abou Elela S. Regulation of ribosomal protein genes: An ordered anarchy. WILEY INTERDISCIPLINARY REVIEWS-RNA 2020; 12:e1632. [PMID: 33038057 PMCID: PMC8047918 DOI: 10.1002/wrna.1632] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Revised: 09/08/2020] [Accepted: 09/23/2020] [Indexed: 02/06/2023]
Abstract
Ribosomal protein genes are among the most highly expressed genes in most cell types. Their products are generally essential for ribosome synthesis, which is the cornerstone for cell growth and proliferation. Many cellular resources are dedicated to producing ribosomal proteins and thus this process needs to be regulated in ways that carefully balance the supply of nascent ribosomal proteins with the demand for new ribosomes. Ribosomal protein genes have classically been viewed as a uniform interconnected regulon regulated in eukaryotic cells by target of rapamycin and protein kinase A pathway in response to changes in growth conditions and/or cellular status. However, recent literature depicts a more complex picture in which the amount of ribosomal proteins produced varies between genes in response to two overlapping regulatory circuits. The first includes the classical general ribosome‐producing program and the second is a gene‐specific feature responsible for fine‐tuning the amount of ribosomal proteins produced from each individual ribosomal gene. Unlike the general pathway that is mainly controlled at the level of transcription and translation, this specific regulation of ribosomal protein genes is largely achieved through changes in pre‐mRNA splicing efficiency and mRNA stability. By combining general and specific regulation, the cell can coordinate ribosome production, while allowing functional specialization and diversity. Here we review the many ways ribosomal protein genes are regulated, with special focus on the emerging role of posttranscriptional regulatory events in fine‐tuning the expression of ribosomal protein genes and its role in controlling the potential variation in ribosome functions. This article is categorized under:Translation > Ribosome Biogenesis Translation > Ribosome Structure/Function Translation > Translation Regulation
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Affiliation(s)
- Cyrielle Petibon
- Département de microbiologie et d'infectiologie, Universite de Sherbrooke, Faculté de Médecine et des Sciences de la Santé, Sherbrooke, Quebec, Canada
| | - Mustafa Malik Ghulam
- Département de microbiologie et d'infectiologie, Universite de Sherbrooke, Faculté de Médecine et des Sciences de la Santé, Sherbrooke, Quebec, Canada
| | - Mathieu Catala
- Département de microbiologie et d'infectiologie, Universite de Sherbrooke, Faculté de Médecine et des Sciences de la Santé, Sherbrooke, Quebec, Canada
| | - Sherif Abou Elela
- Département de microbiologie et d'infectiologie, Universite de Sherbrooke, Faculté de Médecine et des Sciences de la Santé, Sherbrooke, Quebec, Canada
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Zhang Z, Yao M, Zhu G, Chen Y, Chen Y, Sun F, Zhang Y, Wang Q, Shen Z. Identification and subcellular localization of splicing factor arginine/serine-rich 10 in the microsporidian Nosema bombycis. J Invertebr Pathol 2020; 174:107441. [PMID: 32659232 DOI: 10.1016/j.jip.2020.107441] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Revised: 07/02/2020] [Accepted: 07/06/2020] [Indexed: 12/14/2022]
Abstract
Splicing factors are important components of RNA editing in eukaryotic organisms and can produce many functional and coding genes, which is an indispensable step for the correct expression of corresponding proteins. In this study, we identified splicing factor arginine/serine-rich 10 protein in the microsporidian Nosema bombycis and named it NbSRSF10. The NbSRSF10 gene contains a complete ORF of 1449 bp in length that encodes a 482-amino acid polypeptide. The isoelectric point (pI) of the protein encoded by NbSRSF10 gene was 4.94. NbSRSF10 has a molecular weight of 54.6 kD and has no signal peptide. NbSRSF10 is comprised of arginine (11.41%), glutamic acid (11.41%) and serine (9.54%) among the total amino acids, and 7 α-helix, 7 β-sheet and 15 random coils in secondary structure, and contains 71 phosphorylation sites, 22 N-glycosylation sites and 20 O-glycosylation sites. The three-dimensional structure of NbSRSF10 is similar to that of transformer-2 beta of Homo sapiens (hTra2-β). Indirect immunofluorescence showed that the NbSRSF10 is localized in the cytoplasm of the dormant microsporidian spore and is transferred to the nuclei when N. bombycis develops into the proliferative and sporogonic phase. qPCR revealed that the relative expression of NbSRSF10 increased in the meronts stage and was found at a relatively low level in the sporogonic phase of development of N. bombycis, and was up-regulated again during infection in the host cell and early proliferative phase of second life cycle. These results suggested that the NbSRSF10 may participate in the whole life cycle and play an important role in transcription regulation of N. bombycis.
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Affiliation(s)
- Zhilin Zhang
- Jiangsu University of Science and Technology, Zhenjiang 212018, Jiangsu Province, China
| | - Mingshuai Yao
- Jiangsu University of Science and Technology, Zhenjiang 212018, Jiangsu Province, China
| | - Guanyu Zhu
- Jiangsu University of Science and Technology, Zhenjiang 212018, Jiangsu Province, China
| | - Yong Chen
- Jiangsu University of Science and Technology, Zhenjiang 212018, Jiangsu Province, China
| | - Ying Chen
- Jiangsu University of Science and Technology, Zhenjiang 212018, Jiangsu Province, China
| | - Fuzhen Sun
- Jiangsu University of Science and Technology, Zhenjiang 212018, Jiangsu Province, China
| | - Yiling Zhang
- Jiangsu University of Science and Technology, Zhenjiang 212018, Jiangsu Province, China; Sericultural Research Institute, Chinese Academy of Agricultural Sciences, Zhenjiang 212018, Jiangsu Province, China
| | - Qiang Wang
- Jiangsu University of Science and Technology, Zhenjiang 212018, Jiangsu Province, China; Sericultural Research Institute, Chinese Academy of Agricultural Sciences, Zhenjiang 212018, Jiangsu Province, China
| | - Zhongyuan Shen
- Jiangsu University of Science and Technology, Zhenjiang 212018, Jiangsu Province, China; Sericultural Research Institute, Chinese Academy of Agricultural Sciences, Zhenjiang 212018, Jiangsu Province, China.
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13
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Wadi L, Reinke AW. Evolution of microsporidia: An extremely successful group of eukaryotic intracellular parasites. PLoS Pathog 2020; 16:e1008276. [PMID: 32053705 PMCID: PMC7017984 DOI: 10.1371/journal.ppat.1008276] [Citation(s) in RCA: 63] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Affiliation(s)
- Lina Wadi
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Aaron W. Reinke
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
- * E-mail:
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14
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Corsaro D, Walochnik J, Venditti D, Hauröder B, Michel R. Solving an old enigma: Morellospora saccamoebae gen. nov., sp. nov. (Rozellomycota), a Sphaerita-like parasite of free-living amoebae. Parasitol Res 2020; 119:925-934. [PMID: 32048025 DOI: 10.1007/s00436-020-06623-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Accepted: 02/05/2020] [Indexed: 12/21/2022]
Abstract
The Rozellomycota form a lineage basal or sister to the Fungi, ancestor of Microsporidia. Their biodiversity is very rich but remains poorly characterized. The few known species are all parasites, whether of water molds and algae (Rozella), crustaceans (Mitosporidium), or as endonuclear parasites of amoebae (Nucleophaga, Paramicrosporidium). Since the nineteenth century, intracytoplasmic parasites of various protozoa have been described as species of the same genus Sphaerita. However, it was later thought possible to separate these parasites into at least two distinct groups, those forming flagellated zoospores, prevalent in Euglena and other flagellates, and those forming immobile spores, found mainly in free-living and endozoic amoebae. Herein, we report the recovery of a strain of the free-living amoeba species Saccamoeba lacustris, naturally infected by an intracytoplasmic parasite, which under light microscope has a morphology consistent with that of Sphaerita. Biomolecular analyses were thus performed. Our results show that the intracytoplasmic parasite of Saccamoeba belongs to the same subgroup of Mitosporidium and that it forms a new genus within Rozellomycota, Morellospora, that corresponds to the former spore-forming Sphaerita-like parasites of amoebae.
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Affiliation(s)
- Daniele Corsaro
- CHLAREAS, 12 rue du Maconnais, F-54500, Vandoeuvre-lès-Nancy, France.
| | - Julia Walochnik
- Molecular Parasitology, Institute of Specific Prophylaxis and Tropical Medicine, Medical University of Vienna, Kinderspitalgasse 15, 1095, Vienna, Austria
| | - Danielle Venditti
- CHLAREAS, 12 rue du Maconnais, F-54500, Vandoeuvre-lès-Nancy, France
| | - Bärbel Hauröder
- Department of Pathology, Electron Microscopy Facility, Bundeswehr Central Hospital Koblenz, Andernacher Strasse 100, 56070, Koblenz, Germany
| | - Rolf Michel
- Department of Pathology, Electron Microscopy Facility, Bundeswehr Central Hospital Koblenz, Andernacher Strasse 100, 56070, Koblenz, Germany
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15
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Haag KL, Pombert JF, Sun Y, de Albuquerque NRM, Batliner B, Fields P, Lopes TF, Ebert D. Microsporidia with Vertical Transmission Were Likely Shaped by Nonadaptive Processes. Genome Biol Evol 2020; 12:3599-3614. [PMID: 31825473 PMCID: PMC6944219 DOI: 10.1093/gbe/evz270] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/05/2019] [Indexed: 12/14/2022] Open
Abstract
Microsporidia have the leanest genomes among eukaryotes, and their physiological and genomic simplicity has been attributed to their intracellular, obligate parasitic life-style. However, not all microsporidia genomes are small or lean, with the largest dwarfing the smallest ones by at least an order of magnitude. To better understand the evolutionary mechanisms behind this genomic diversification, we explore here two clades of microsporidia with distinct life histories, Ordospora and Hamiltosporidium, parasitizing the same host species, Daphnia magna. Based on seven newly assembled genomes, we show that mixed-mode transmission (the combination of horizontal and vertical transmission), which occurs in Hamiltosporidium, is found to be associated with larger and AT-biased genomes, more genes, and longer intergenic regions, as compared with the exclusively horizontally transmitted Ordospora. Furthermore, the Hamiltosporidium genome assemblies contain a variety of repetitive elements and long segmental duplications. We show that there is an excess of nonsynonymous substitutions in the microsporidia with mixed-mode transmission, which cannot be solely attributed to the lack of recombination, suggesting that bursts of genome size in these microsporidia result primarily from genetic drift. Overall, these findings suggest that the switch from a horizontal-only to a mixed mode of transmission likely produces population bottlenecks in Hamiltosporidium species, therefore reducing the effectiveness of natural selection, and allowing their genomic features to be largely shaped by nonadaptive processes.
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Affiliation(s)
- Karen L Haag
- Department of Genetics and Post-Graduation Program of Genetics and Molecular Biology, Federal University of Rio Grande do Sul, Porto Alegre, Brazil
| | | | - Yukun Sun
- Department of Biology, Illinois Institute of Technology
| | - Nathalia Rammé M de Albuquerque
- Department of Genetics and Post-Graduation Program of Genetics and Molecular Biology, Federal University of Rio Grande do Sul, Porto Alegre, Brazil
| | | | - Peter Fields
- Department of Environmental Sciences, Zoology, Basel University, Switzerland
| | - Tiago Falcon Lopes
- Department of Genetics and Post-Graduation Program of Genetics and Molecular Biology, Federal University of Rio Grande do Sul, Porto Alegre, Brazil
| | - Dieter Ebert
- Department of Environmental Sciences, Zoology, Basel University, Switzerland
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16
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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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