Transcriptionally promiscuous \u201cblurry\u201d promoters in Tc1/mariner transposons allow transcription in distantly related genomes

Antonio Palazzo,Oliver Walisko,Csaba Miskey,René Massimiliano Marsano,Andrea Gerbino,Patrizio Lorusso,Zoltán Ivics,Carlo Marya Thomas Marobbio

doi:10.1186/s13100-019-0155-6

Abstract

BackgroundWe have recently described a peculiar feature of the promoters in two Drosophila Tc1-like elements, Bari1 and Bari3. The AT-richness and the presence of weak core-promoter motifs make these promoters, that we have defined “blurry”, able to activate transcription of a reporter gene in cellular systems as diverse as fly, human, yeast and bacteria. In order to clarify whether the blurry promoter is a specific feature of the Bari transposon family, we have extended this study to promoters isolated from three additional DNA transposon and from two additional LTR retrotransposons.ResultsHere we show that the blurry promoter is also a feature of two vertebrate transposable elements, Sleeping Beauty and Hsmar1, belonging to the Tc1/mariner superfamily. In contrast, this feature is not shared by the promoter of the hobo transposon, which belongs to the hAT superfamily, nor by LTR retrotransposon-derived promoters, which, in general, do not activate transcription when introduced into non-related genomes.ConclusionsOur results suggest that the blurry promoter could be a shared feature of the members of the Tc1/mariner superfamily with possible evolutionary and biotechnological implications.

Highlights

We have recently described a peculiar feature of the promoters in two Drosophila Tc1-like elements, Bari1 and Bari3
Our results suggest that the blurry promoter is a feature shared by the elements of the Tc1/mariner superfamily tested in this study, while the promoters of hobo, Tirant and Zam are usually functional within a limited range of genomic environments strictly related to the species of origin
The promoter of the hobo element was chosen as an outgroup to Class II of transposons, whereas Tirant and ZAM were used as representative elements of the LTR retrotransposons belonging to the Ty3-gypsy superfamily

Summary

Introduction

We have recently described a peculiar feature of the promoters in two Drosophila Tc1-like elements, Bari and Bari. Transposable elements (TEs) are widespread genetic elements that have played a fundamental role in genome evolution [1], contributing to generating diversity, both at small and large scale [2], and to evolving new functions through molecular domestication [3] or exaptation [4]. Their ubiquitous presence in the genomes of extant species suggests an ancient history dating back to early living organisms, as well as an extraordinary ability to overcome the canonical genetic barriers between species, the latter being an intrinsic feature of the horizontal gene transfer process (HGT). Horizontal Transposon Transfer (HTT) is an important mechanism that mobile genetic elements undertake to escape extinction

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Conclusion