Dataset Information

L1Base: from functional annotation to prediction of active LINE-1 elements.

ABSTRACT: L1Base is a dedicated database containing putatively active LINE-1 (L1) insertions residing in human and rodent genomes that are as follows: (i) intact in the two open reading frames (ORFs), full-length L1s (FLI-L1s) and (ii) intact ORF2 but disrupted ORF1 (ORF2-L1s). In addition, due to their regulatory potential, the full-length (>6000 bp) non-intact L1s (FLnI-L1s) were also included in the database. Application of a novel annotation methodology, L1Xplorer, allowed in-depth annotation of functional sequence features important for L1 activity, such as transcription factor binding sites and amino acid residues. The L1Base is available online at http://l1base.molgen.mpg.de. In addition, the data stored in the database can be accessed from the Ensembl web browser via a DAS service (http://l1das.molgen.mpg.de:8080/das).

SUBMITTER: Penzkofer T

PROVIDER: S-EPMC539998 | biostudies-literature | 2005 Jan

REPOSITORIES: biostudies-literature

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L1Base: from functional annotation to prediction of active LINE-1 elements.

Penzkofer Tobias T Dandekar Thomas T Zemojtel Tomasz T

Nucleic acids research 20050101 Database issue

L1Base is a dedicated database containing putatively active LINE-1 (L1) insertions residing in human and rodent genomes that are as follows: (i) intact in the two open reading frames (ORFs), full-length L1s (FLI-L1s) and (ii) intact ORF2 but disrupted ORF1 (ORF2-L1s). In addition, due to their regulatory potential, the full-length (>6000 bp) non-intact L1s (FLnI-L1s) were also included in the database. Application of a novel annotation methodology, L1Xplorer, allowed in-depth annotation of funct ...[more]

PMID: 15608246

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Project description:BackgroundAedes aegypti is a vector for the (re-)emerging human pathogens dengue, chikungunya, yellow fever and Zika viruses. Almost half of the Ae. aegypti genome is comprised of transposable elements (TEs). Transposons have been linked to diverse cellular processes, including the establishment of viral persistence in insects, an essential step in the transmission of vector-borne viruses. However, up until now it has not been possible to study the overall proteome derived from an organism's mobile genetic elements, partly due to the highly divergent nature of TEs. Furthermore, as for many non-model organisms, incomplete genome annotation has hampered proteomic studies on Ae. aegypti.ResultsWe analysed the Ae. aegypti proteome using our new proteomics informed by transcriptomics (PIT) technique, which bypasses the need for genome annotation by identifying proteins through matched transcriptomic (rather than genomic) data. Our data vastly increase the number of experimentally confirmed Ae. aegypti proteins. The PIT analysis also identified hotspots of incomplete genome annotation, and showed that poor sequence and assembly quality do not explain all annotation gaps. Finally, in a proof-of-principle study, we developed criteria for the characterisation of proteomically active TEs. Protein expression did not correlate with a TE's genomic abundance at different levels of classification. Most notably, long terminal repeat (LTR) retrotransposons were markedly enriched compared to other elements. PIT was superior to 'conventional' proteomic approaches in both our transposon and genome annotation analyses.ConclusionsWe present the first proteomic characterisation of an organism's repertoire of mobile genetic elements, which will open new avenues of research into the function of transposon proteins in health and disease. Furthermore, our study provides a proof-of-concept that PIT can be used to evaluate a genome's annotation to guide annotation efforts which has the potential to improve the efficiency of annotation projects in non-model organisms. PIT therefore represents a valuable new tool to study the biology of the important vector species Ae. aegypti, including its role in transmitting emerging viruses of global public health concern.

Project description:BackgroundTransposable elements (TEs) are mobile DNA sequences known as drivers of genome evolution. Their impacts have been widely studied in animals, plants and insects, but little is known about them in microalgae. In a previous study, we compared the genetic polymorphisms between strains of the haptophyte microalga Tisochrysis lutea and suggested the involvement of active autonomous TEs in their genome evolution.ResultsTo identify potentially autonomous TEs, we designed a pipeline named PiRATE (Pipeline to Retrieve and Annotate Transposable Elements, download: https://doi.org/10.17882/51795 ), and conducted an accurate TE annotation on a new genome assembly of T. lutea. PiRATE is composed of detection, classification and annotation steps. Its detection step combines multiple, existing analysis packages representing all major approaches for TE detection and its classification step was optimized for microalgal genomes. The efficiency of the detection and classification steps was evaluated with data on the model species Arabidopsis thaliana. PiRATE detected 81% of the TE families of A. thaliana and correctly classified 75% of them. We applied PiRATE to T. lutea genomic data and established that its genome contains 15.89% Class I and 4.95% Class II TEs. In these, 3.79 and 17.05% correspond to potentially autonomous and non-autonomous TEs, respectively. Annotation data was combined with transcriptomic and proteomic data to identify potentially active autonomous TEs. We identified 17 expressed TE families and, among these, a TIR/Mariner and a TIR/hAT family were able to synthesize their transposase. Both these TE families were among the three highest expressed genes in a previous transcriptomic study and are composed of highly similar copies throughout the genome of T. lutea. This sum of evidence reveals that both these TE families could be capable of transposing or triggering the transposition of potential related MITE elements.ConclusionThis manuscript provides an example of a de novo transposable element annotation of a non-model organism characterized by a fragmented genome assembly and belonging to a poorly studied phylum at genomic level. Integration of multi-omics data enabled the discovery of potential mobile TEs and opens the way for new discoveries on the role of these repeated elements in genomic evolution of microalgae.

Dataset Information

L1Base: from functional annotation to prediction of active LINE-1 elements.

Publications

L1Base: from functional annotation to prediction of active LINE-1 elements.

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