Martí Carreras, Joan

Universitat Autònoma de Barcelona. Facultat de Biociències

Diposit Digital de Documents de la UAB

Backtracking of co-opted TEs (2,3)  The aim of this essay is to explain the importance of transposable elements (TEs) for host genome evolution. TEs contribute to genomic evolution by host co-optation of their codificant and regulatory sequences. In order to set forth this topic, an hypothetical evolutive dynamic is proposed, regarding since the infection of transposable elements into the population, until the elements are lost or co-opted. Also, a some examples will be provided, in an attempt to show different molecular systems that had been formed by molecular co-optation of transposable elements.   From infection to co-optation: Long  term dynamics of transposable elements and host genomes Introduction Conclusions    This are the concluding remarks: • TEs have been recurrently recruited into genomes and hence, TEs have formed or rewired new gene regulatory networks. • Molecular dynamics of TEs are complex, and different processes happen during their so-called “struggle-for-life”: Infection  of host populations, burst transposition, maintenance into the population, accumulation of variation, depletion of    transposable ability and domesticating mutations between others. • Co-optation of TEs is broad. TEs can be co-opted into different roles: efficiency binding site for the POL II, POL III, for binding activator elements (enhancers) transcriptional factors, heterochromatic factors (insulators or heterochromatin         extenders), alternative splice sites and different polyadenylation sites. • Co-optation of transposase DNA-binding domains may lead to retain a group of unlinked binding sites, dispersed in the genome, and/or co-opt their interactions with host regulatory proteins. • Every transposase has cis-preference for its related TIR sequence (or close-related TIR sequences) therefore, determining the future specificity . • Modular evolution of proteins plays a special role with co-optation of TEs. TEs ORFs can be combined and shuffled with host domains, leading to the formation of new protein domains, new combinations and therefore, novel functions.     Co-optation is defined as the process by which a structure or system with an original function adds or changes a new function towards the nucleus, cell or organism. Concretely, in this context, co-optation is the processes by a TE sequence become part of a pre-existent system of the host genome, giving rise to an evolutionary novelty (1).  Co-optation Bibliography    Mclennan DA. The Concept of Co-option : Why Evolution Often Looks Miraculous. 2008:247–258. doi:10.1007/s12052-008-0053-8 (1) Le Rouzic A, Capy P. The first steps of transposable elements invasion: parasitic strategy vs. genetic drift. Genet Soc Am. 2005;169(2):1033–43. doi:10.1534/genetics.104.031211 (2) Deacon TW. Relaxed selection and the role of epigenesis in the evolution of language. Oxford Handb Dev Behav Neurosci. 2009:730–752.(3) Rebollo R, Romanish MT, Mager DL. Transposable elements: an abundant and natural source of regulatory sequences for host genes. Annu Rev Genet. 2012;46:21–42. doi:10.1146/annurev-genet-110711-155621(4) Kapitonov V V, Jurka J. RAG1 core and V(D)J recombination signal sequences were derived from Transib transposons. PLoS Biol. 2005;3(6):e181. doi:10.1371/journal.pbio.0030181. (5)           Insulators TE cis-activating element New TF binding regions New splice sites   Alternative polyadenylation sites Tissue-specific promoters Heterochromatic factor binding regions 1 RAG1 RAG2 1 2 3 1 2 3 1 2 3 1 2 1 2 3 1 2 3 1 2 1 2 3 1 2 1 3 2 1 2 3 2 1 2 3 1 2 3 1 2 Molecular co-optation of a TE: Concepts (4) X X RAG1 RAG2 Co-optation of regulatory networks Molecular co-optation of a TE: the V(D)J system (5) 2 3 V segment D segment J segment C segment Recombination Signal Sequence(RSS) TIR TIR DNA-binding domain NLS Catalytic domain Transib1 (DNA transposon) Retrotranscriptase/transposase Signaling sequences Modified from Rebollo, et al. (4) Co-opted regulatory protein Response-specific regulators 

From infection to co-optation : long term dynamics of transposable elements and host genomes

http://ddd.uab.cat/pub/tfg/2015/141487/TFG_joanmartiicarreras.pdf

From infection to co-optation : long term dynamics of transposable elements and host genomes

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