Genome wide survey, discovery and evolution of repetitive elements in three Entamoeba species.
Name
1471-2164-9-595.pdf
Size
908.96 KB
Format
Adobe PDF
Checksum (MD5)
a6f7a54f9654743e6e0b3fb38e47ba8e
Author(s)
Lorenzi, Hernan
Thiagarajan, Mathangi
Haas, Brian J.
Wortman, Jennifer
Hall, Neil
Caler, Elisabet
Date Issued
December 2008
Journal
BMC Genomics
Publisher
BioMed Central Ltd
Citation
BMC Genomics. 2008 Dec 10;9(1):595
Version
Final published version
Abstract
Background: Identification and mapping of repetitive elements is a key step for accurate gene prediction and overall structural annotation of genomes. During the assembly and annotation of three highly repetitive amoeba genomes, Entamoeba histolytica, Entamoeba dispar, and Entamoeba invadens, we performed comparative sequence analysis to identify and map all class I and class II transposable elements in their sequences. Results: Here, we report the identification of two novel Entamoeba-specific repeats: ERE1 and ERE2; ERE1 is spread across the three genomes and associated with different repeats in a species-specific manner, while ERE2 is unique to E. histolytica. We also report the identification of two novel subfamilies of LINE and SINE retrotransposons in E. dispar and provide evidence for how the different LINE and SINE subfamilies evolved in these species. Additionally, we found a putative transposase-coding gene in E. histolytica and E. dispar related to the mariner transposon Hydargos from E. invadens. The distribution of transposable elements in these genomes is markedly skewed with a tendency of forming clusters. More than 70% of the three genomes have a repeat density below their corresponding average value indicating that transposable elements are not evenly distributed. We show that repeats and repeat-clusters are found at syntenic break points between E. histolytica and E. dispar and hence, could work as recombination hot spots promoting genome rearrangements. Conclusion: The mapping of all transposable elements found in these parasites shows that repeat coverage is up to three times higher than previously reported. LINE, ERE1 and mariner elements were present in the common ancestor to the three Entamoeba species while ERE2 was likely acquired by E. histolytica after its separation from E. dispar. We demonstrate that E. histolytica and E. dispar share their entire repertoire of LINE and SINE retrotransposons and that Eh_SINE3/Ed_SINE1 originated as a chimeric SINE from Eh/Ed_SINE2 and Eh_SINE1/Ed_SINE3. Our work shows that transposable elements are organized in clusters, frequently found at syntenic break points providing insights into their contribution to chromosome instability and therefore, to genomic variation and speciation in these parasites.
MIT Department
Broad Institute of MIT and Harvard
Terms of Use
Creative Commons Attribution
Persistent DSpace Link
DOI of Published Version
https://doi.org/10.1186/1471-2164-9-595
