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Peyretaillade E, Akossi RF, Tournayre J, Delbac F, Wawrzyniak I. How to overcome constraints imposed by microsporidian genome features to ensure gene prediction? J Eukaryot Microbiol 2024:e13038. [PMID: 38934348 DOI: 10.1111/jeu.13038] [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: 03/18/2024] [Revised: 06/03/2024] [Accepted: 06/10/2024] [Indexed: 06/28/2024]
Abstract
Since the advent of sequencing techniques and due to their continuous evolution, it has become easier and less expensive to obtain the complete genome sequence of any organism. Nevertheless, to elucidate all biological processes governing organism development, quality annotation is essential. In genome annotation, predicting gene structure is one of the most important and captivating challenges for computational biology. This aspect of annotation requires continual optimization, particularly for genomes as unusual as those of microsporidia. Indeed, this group of fungal-related parasites exhibits specific features (highly reduced gene sizes, sequences with high rate of evolution) linked to their evolution as intracellular parasites, requiring the implementation of specific annotation approaches to consider all these features. This review aimed to outline these characteristics and to assess the increasingly efficient approaches and tools that have enhanced the accuracy of gene prediction for microsporidia, both in terms of sensitivity and specificity. Subsequently, a final part will be dedicated to postgenomic approaches aimed at reinforcing the annotation data generated by prediction software. These approaches include the characterization of other understudied genes, such as those encoding regulatory noncoding RNAs or very small proteins, which also play crucial roles in the life cycle of these microorganisms.
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Affiliation(s)
| | - Reginal F Akossi
- LMGE, CNRS, Université Clermont Auvergne, Clermont-Ferrand, France
| | - Jérémy Tournayre
- INRAE, UMR Herbivores, Université Clermont Auvergne, VetAgro Sup, Saint-Genès-Champanelle, France
| | - Frédéric Delbac
- LMGE, CNRS, Université Clermont Auvergne, Clermont-Ferrand, France
| | - Ivan Wawrzyniak
- LMGE, CNRS, Université Clermont Auvergne, Clermont-Ferrand, France
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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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Chanarat S. Transcription machinery of the minimalist: comparative genomic analysis provides insights into the (de)regulated transcription mechanism of microsporidia - fungal-relative parasites. Transcription 2023; 14:1-17. [PMID: 36757099 PMCID: PMC10353337 DOI: 10.1080/21541264.2023.2174765] [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: 11/14/2022] [Revised: 01/24/2023] [Accepted: 01/26/2023] [Indexed: 02/10/2023] Open
Abstract
Microsporidia are eukaryotic obligate intracellular parasites closely related to fungi. Co-evolving with infected hosts, microsporidia have highly reduced their genomes and lacked several biological components. As it is beneficial for intracellular parasites like microsporidia to reduce their genome size, it is therefore reasonable to assume that genes encoding multifactorial complex machinery of transcription could be a potential target to be excluded from microsporidian genomes during the reductive evolution. In such a case, an evolutionary dilemma occurs because microsporidia cannot remove all transcription-machinery-encoding genes, products of which are essential for initialthe initial steps of gene expression. Here, I propose that while genes encoding core machinery are conserved, several genes known to function in fine-tune regulation of transcription are absent. This genome compaction strategy may come at the cost of loosely regulated or less controllable transcription. Alternatively, analogous to microsporidian polar tube, the parasites may have specialized factors to regulate their RNA synthesis.
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Affiliation(s)
- Sittinan Chanarat
- Laboratory of Molecular Cell Biology, Department of Biochemistry and Center for Excellence in Protein and Enzyme Technology, Faculty of Science, Mahidol University, Bangkok, Thailand
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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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Draft Genome Sequence of Tubulinosema ratisbonensis, a Microsporidian Species Infecting the Model Organism Drosophila melanogaster. Microbiol Resour Announc 2019; 8:8/31/e00077-19. [PMID: 31371528 PMCID: PMC6675976 DOI: 10.1128/mra.00077-19] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We present the draft genome sequence of Tubulinosema ratisbonensis, a microsporidium species infecting Drosophila melanogaster A total of 3,013 protein-encoding genes and an array of transposable elements were identified. This work represents a necessary step to develop a novel model of host-parasite relationships using the highly tractable genetic model D. melanogaster.
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Urbieta-Magro A, Higes M, Meana A, Gómez-Moracho T, Rodríguez-García C, Barrios L, Martín-Hernández R. The levels of natural Nosema spp. infection in Apis mellifera iberiensis brood stages. Int J Parasitol 2019; 49:657-667. [PMID: 31170411 DOI: 10.1016/j.ijpara.2019.04.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2019] [Revised: 04/08/2019] [Accepted: 04/10/2019] [Indexed: 02/06/2023]
Abstract
Nosema ceranae is the most prevalent endoparasite of Apis mellifera iberiensis and it is a major health problem for bees worldwide. The infective capacity of N. ceranae has been demonstrated experimentally in honey bee brood, however no data are available about its prevalence in brood under natural conditions. Thus, brood combs from 10 different hives were analyzed over two consecutive years, taking samples before and after winter. A total of 1433 larvae/pupae were analyzed individually and N. ceranae (3.53%) was the microsporidian most frequently detected, as opposed to Nosema apis (0.42%) which was more frequently detected in conjunction with N. ceranae (0.71%). The active multiplication of both microsporidians was confirmed by the expression (real-time-PCR) of the N. ceranae polar tube protein 3 gene and/or the N. apis RNA polymerase II gene in 24% of the brood samples positive for Nosema spp. Both genes are related to microsporidian multiplication. As such, N. ceranae multiplication was confirmed in 1.06% of the samples, while N. apis multiplication was only observed in co-infections with N. ceranae (0.07%). Brood cells were analyzed for the presence of Nosema spp., as those are the immediate environment where the brood stages develop. The brood samples infected by Nosema spp. were in brood cells in which that microsporidians were not detected, while brood cells positive for N. ceranae hosted brood stages that were not apparently infected, indicating that this is unlikely to be the main pathway of infection. Finally, the colonies with brood infected by N. ceranae showed higher levels (numbers) of infected adult bees, although the differences were not significant before (P = 0.260), during (P = 0.055) or after (P = 0.056) brood sampling. These results show that N. ceranae is a bee parasite ubiquitous to all members of the colony, irrespective of the age of the bee. It is also of veterinary interest and should be considered when studying the epidemiology of the disease.
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Affiliation(s)
- Almudena Urbieta-Magro
- Laboratorio de Patología Apícola, Centro de Investigación Apícola y Agroambiental (CIAPA), Instituto Regional de Investigación y Desarrollo Agroalimentario y Forestal (IRIAF), Consejería de Agricultura de la Junta de Comunidades de Castilla-La Mancha, Camino de San Martín s/n, 19180 Marchamalo, Guadalajara, Spain
| | - Mariano Higes
- Laboratorio de Patología Apícola, Centro de Investigación Apícola y Agroambiental (CIAPA), Instituto Regional de Investigación y Desarrollo Agroalimentario y Forestal (IRIAF), Consejería de Agricultura de la Junta de Comunidades de Castilla-La Mancha, Camino de San Martín s/n, 19180 Marchamalo, Guadalajara, Spain
| | - Aránzazu Meana
- Departamento de Sanidad Animal, Facultad de Veterinaria, Universidad Complutense de Madrid, Spain
| | - Tamara Gómez-Moracho
- Laboratorio de Patología Apícola, Centro de Investigación Apícola y Agroambiental (CIAPA), Instituto Regional de Investigación y Desarrollo Agroalimentario y Forestal (IRIAF), Consejería de Agricultura de la Junta de Comunidades de Castilla-La Mancha, Camino de San Martín s/n, 19180 Marchamalo, Guadalajara, Spain
| | - Cristina Rodríguez-García
- Laboratorio de Patología Apícola, Centro de Investigación Apícola y Agroambiental (CIAPA), Instituto Regional de Investigación y Desarrollo Agroalimentario y Forestal (IRIAF), Consejería de Agricultura de la Junta de Comunidades de Castilla-La Mancha, Camino de San Martín s/n, 19180 Marchamalo, Guadalajara, Spain
| | - Laura Barrios
- Statistics Department, Computing Center SGAI-CSIC, Madrid, Spain
| | - Raquel Martín-Hernández
- Laboratorio de Patología Apícola, Centro de Investigación Apícola y Agroambiental (CIAPA), Instituto Regional de Investigación y Desarrollo Agroalimentario y Forestal (IRIAF), Consejería de Agricultura de la Junta de Comunidades de Castilla-La Mancha, Camino de San Martín s/n, 19180 Marchamalo, Guadalajara, Spain; Instituto de Recursos Humanos para la Ciencia y la Tecnología (INCRECYT-FEDER), Fundación Parque Científico y Tecnológico de Castilla - La Mancha, Spain.
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Åsman AKM, Curtis BA, Archibald JM. Nucleomorph Small RNAs in Cryptophyte and Chlorarachniophyte Algae. Genome Biol Evol 2019; 11:1117-1134. [PMID: 30949682 PMCID: PMC6461891 DOI: 10.1093/gbe/evz064] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/15/2019] [Indexed: 12/27/2022] Open
Abstract
The regulation of gene expression and RNA maturation underlies fundamental processes such as cell homeostasis, development, and stress acclimation. The biogenesis and modification of RNA is tightly controlled by an array of regulatory RNAs and nucleic acid-binding proteins. While the role of small RNAs (sRNAs) in gene expression has been studied in-depth in select model organisms, little is known about sRNA biology across the eukaryotic tree of life. We used deep sequencing to explore the repertoires of sRNAs encoded by the miniaturized, endosymbiotically derived “nucleomorph” genomes of two single-celled algae, the cryptophyte Guillardia theta and the chlorarachniophyte Bigelowiella natans. A total of 32.3 and 35.3 million reads were generated from G. theta and B. natans, respectively. In G. theta, we identified nucleomorph U1, U2, and U4 spliceosomal small nuclear RNAs (snRNAs) as well as 11 C/D box small nucleolar RNAs (snoRNAs), five of which have potential plant and animal homologs. The snoRNAs are predicted to perform 2′-O methylation of rRNA (but not snRNA). In B. natans, we found the previously undetected 5S rRNA as well as six orphan sRNAs. Analysis of chlorarachniophyte snRNAs shed light on the removal of the miniature 18–21 nt introns found in B. natans nucleomorph genes. Neither of the nucleomorph genomes appears to encode RNA pseudouridylation machinery, and U5 snRNA cannot be found in the cryptophyte G. theta. Considering the central roles of U5 snRNA and RNA modifications in other organisms, cytoplasm-to-nucleomorph RNA shuttling in cryptophyte algae is a distinct possibility.
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Affiliation(s)
- Anna K M Åsman
- Department of Biochemistry and Molecular Biology, Dalhousie University, Nova Scotia, Canada.,Department of Molecular Sciences, Uppsala BioCenter, Swedish University of Agricultural Sciences and Linnean Center for Plant Biology, Uppsala, Sweden
| | - Bruce A Curtis
- Department of Biochemistry and Molecular Biology, Dalhousie University, Nova Scotia, Canada
| | - John M Archibald
- Department of Biochemistry and Molecular Biology, Dalhousie University, Nova Scotia, Canada
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Whelan TA, Lee NT, Lee RCH, Fast NM. Microsporidian Introns Retained against a Background of Genome Reduction: Characterization of an Unusual Set of Introns. Genome Biol Evol 2019; 11:263-269. [PMID: 30496512 PMCID: PMC6349667 DOI: 10.1093/gbe/evy260] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/24/2018] [Indexed: 01/22/2023] Open
Abstract
Spliceosomal introns are ubiquitous features of eukaryotic genomes, but the mechanisms responsible for their loss and gain are difficult to identify. Microsporidia are obligate intracellular parasites that have significantly reduced genomes and, as a result, have lost many if not all of their introns. In the microsporidian Encephalitozoon cuniculi, a relatively long intron was identified and was spliced at higher levels than the remaining introns. This long intron is part of a set of unique introns in two unrelated genes that show high levels of sequence conservation across diverse microsporidia. The introns possess a unique internal conserved region, which overlaps with a shared, predicted stem–loop structure. The unusual similarity and retention of these long introns in reduced microsporidian genomes could indicate that these introns function similarly, are homologous, or both. Regardless, the significant genome reduction in microsporidia provides a rare opportunity to understand intron evolution.
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Affiliation(s)
- Thomas A Whelan
- Biodiversity Research Centre and Department of Botany, University of British Columbia, Vancouver, British Columbia, Canada
| | - Nicole T Lee
- Biodiversity Research Centre and Department of Botany, University of British Columbia, Vancouver, British Columbia, Canada
| | - Renny C H Lee
- Biodiversity Research Centre and Department of Botany, University of British Columbia, Vancouver, British Columbia, Canada
| | - Naomi M Fast
- Biodiversity Research Centre and Department of Botany, University of British Columbia, Vancouver, British Columbia, Canada
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