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Castanera R, Pérez G, López L, Sancho R, Santoyo F, Alfaro M, Gabaldón T, Pisabarro AG, Oguiza JA, Ramírez L. Highly expressed captured genes and cross-kingdom domains present in Helitrons create novel diversity in Pleurotus ostreatus and other fungi. BMC Genomics 2014; 15:1071. [PMID: 25480150 PMCID: PMC4289320 DOI: 10.1186/1471-2164-15-1071] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2014] [Accepted: 11/14/2014] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Helitrons are class-II eukaryotic transposons that transpose via a rolling circle mechanism. Due to their ability to capture and mobilize gene fragments, they play an important role in the evolution of their host genomes. We have used a bioinformatics approach for the identification of helitrons in two Pleurotus ostreatus genomes using de novo detection and homology-based searching. We have analyzed the presence of helitron-captured genes as well as the expansion of helitron-specific helicases in fungi and performed a phylogenetic analysis of their conserved domains with other representative eukaryotic species. RESULTS Our results show the presence of two helitron families in P. ostreatus that disrupt gene colinearity and cause a lack of synteny between their genomes. Both putative autonomous and non-autonomous helitrons were transcriptionally active, and some of them carried highly expressed captured genes of unknown origin and function. In addition, both families contained eukaryotic, bacterial and viral domains within the helitron's boundaries. A phylogenetic reconstruction of RepHel helicases using the Helitron-like and PIF1-like helicase conserved domains revealed a polyphyletic origin for eukaryotic helitrons. CONCLUSION P. ostreatus helitrons display features similar to other eukaryotic helitrons and do not tend to capture host genes or gene fragments. The occurrence of genes probably captured from other hosts inside the helitrons boundaries pose the hypothesis that an ancient horizontal transfer mechanism could have taken place. The viral domains found in some of these genes and the polyphyletic origin of RepHel helicases in the eukaryotic kingdom suggests that virus could have played a role in a putative lateral transfer of helitrons within the eukaryotic kingdom. The high similarity of some helitrons, along with the transcriptional activity of its RepHel helicases indicates that these elements are still active in the genome of P. ostreatus.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | - Lucía Ramírez
- Department of Agrarian Production, Genetics and Microbiology Research Group, Public University of Navarre, 31006 Pamplona, Navarre, Spain.
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Bushley KE, Raja R, Jaiswal P, Cumbie JS, Nonogaki M, Boyd AE, Owensby CA, Knaus BJ, Elser J, Miller D, Di Y, McPhail KL, Spatafora JW. The genome of tolypocladium inflatum: evolution, organization, and expression of the cyclosporin biosynthetic gene cluster. PLoS Genet 2013; 9:e1003496. [PMID: 23818858 PMCID: PMC3688495 DOI: 10.1371/journal.pgen.1003496] [Citation(s) in RCA: 112] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2012] [Accepted: 03/20/2013] [Indexed: 01/07/2023] Open
Abstract
The ascomycete fungus Tolypocladium inflatum, a pathogen of beetle larvae, is best known as the producer of the immunosuppressant drug cyclosporin. The draft genome of T. inflatum strain NRRL 8044 (ATCC 34921), the isolate from which cyclosporin was first isolated, is presented along with comparative analyses of the biosynthesis of cyclosporin and other secondary metabolites in T. inflatum and related taxa. Phylogenomic analyses reveal previously undetected and complex patterns of homology between the nonribosomal peptide synthetase (NRPS) that encodes for cyclosporin synthetase (simA) and those of other secondary metabolites with activities against insects (e.g., beauvericin, destruxins, etc.), and demonstrate the roles of module duplication and gene fusion in diversification of NRPSs. The secondary metabolite gene cluster responsible for cyclosporin biosynthesis is described. In addition to genes necessary for cyclosporin biosynthesis, it harbors a gene for a cyclophilin, which is a member of a family of immunophilins known to bind cyclosporin. Comparative analyses support a lineage specific origin of the cyclosporin gene cluster rather than horizontal gene transfer from bacteria or other fungi. RNA-Seq transcriptome analyses in a cyclosporin-inducing medium delineate the boundaries of the cyclosporin cluster and reveal high levels of expression of the gene cluster cyclophilin. In medium containing insect hemolymph, weaker but significant upregulation of several genes within the cyclosporin cluster, including the highly expressed cyclophilin gene, was observed. T. inflatum also represents the first reference draft genome of Ophiocordycipitaceae, a third family of insect pathogenic fungi within the fungal order Hypocreales, and supports parallel and qualitatively distinct radiations of insect pathogens. The T. inflatum genome provides additional insight into the evolution and biosynthesis of cyclosporin and lays a foundation for further investigations of the role of secondary metabolite gene clusters and their metabolites in fungal biology.
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Affiliation(s)
- Kathryn E. Bushley
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon, United States of America
- * E-mail:
| | - Rajani Raja
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon, United States of America
| | - Pankaj Jaiswal
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon, United States of America
| | - Jason S. Cumbie
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon, United States of America
| | - Mariko Nonogaki
- College of Pharmacy, Oregon State University, Corvallis, Oregon, United States of America
| | - Alexander E. Boyd
- Center for Genome Research & Biocomputing, Oregon State University, Corvallis, Oregon, United States of America
| | - C. Alisha Owensby
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon, United States of America
| | - Brian J. Knaus
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon, United States of America
| | - Justin Elser
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon, United States of America
| | - Daniel Miller
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon, United States of America
| | - Yanming Di
- Department of Statistics, Oregon State University, Corvallis, Oregon, United States of America
| | - Kerry L. McPhail
- College of Pharmacy, Oregon State University, Corvallis, Oregon, United States of America
| | - Joseph W. Spatafora
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon, United States of America
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