A machine learning based framework to identify and classify long terminal repeat retrotransposons

PLoS Comput Biol. 2018 Apr 23;14(4):e1006097. doi: 10.1371/journal.pcbi.1006097. eCollection 2018 Apr.

Abstract

Transposable elements (TEs) are repetitive nucleotide sequences that make up a large portion of eukaryotic genomes. They can move and duplicate within a genome, increasing genome size and contributing to genetic diversity within and across species. Accurate identification and classification of TEs present in a genome is an important step towards understanding their effects on genes and their role in genome evolution. We introduce TE-Learner, a framework based on machine learning that automatically identifies TEs in a given genome and assigns a classification to them. We present an implementation of our framework towards LTR retrotransposons, a particular type of TEs characterized by having long terminal repeats (LTRs) at their boundaries. We evaluate the predictive performance of our framework on the well-annotated genomes of Drosophila melanogaster and Arabidopsis thaliana and we compare our results for three LTR retrotransposon superfamilies with the results of three widely used methods for TE identification or classification: RepeatMasker, Censor and LtrDigest. In contrast to these methods, TE-Learner is the first to incorporate machine learning techniques, outperforming these methods in terms of predictive performance, while able to learn models and make predictions efficiently. Moreover, we show that our method was able to identify TEs that none of the above method could find, and we investigated TE-Learner's predictions which did not correspond to an official annotation. It turns out that many of these predictions are in fact strongly homologous to a known TE.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Arabidopsis / genetics
  • Arabidopsis Proteins / genetics
  • Computational Biology
  • Conserved Sequence
  • DNA, Plant / genetics
  • Decision Trees
  • Drosophila Proteins / genetics
  • Drosophila melanogaster / genetics
  • Evolution, Molecular
  • Genome, Insect
  • Genome, Plant
  • Machine Learning*
  • Retroelements*
  • Software
  • Terminal Repeat Sequences*

Substances

  • Arabidopsis Proteins
  • DNA, Plant
  • Drosophila Proteins
  • Retroelements

Grants and funding

This work was supported by the Explorative Scientific Co-operation Programme between KU Leuven and São Paulo State University (UNESP), the Research Foundation Flanders (FWO-Vlaanderen) [project G.0413.09 to EC, postdoctoral grant to CV, grant GA.001.15N (Chist-ERANET call 2013 Adalab project) to JR], the Research Fund KU Leuven, ERC Starting Grant 240186 and IWT-SBO Nemoa to LS, the São Paulo Research Foundation (FAPESP - Brazil) [project 2015/14300-1 to RC, project 2012/24774-2 to CNF, project 2013/15070-4 to CMAC], the National Council for Scientific and Technological Development (CNPq-Brazil) [project 306493/2013-6 to CMAC], and Coordination for the Improvement of Higher Education Personnel (CAPES-Brazil) to EC. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.