Revealing the transposable element dynamics driving evolutionary transitions through direct observation in live cells

Transposable elements are ubiquitous in all forms of life and are major drivers of evolutionary transitions through their disruptive nature and adaptive contributions. To study their dynamics in higher resolution, we genetically engineered transposable elements for tunable expression inside living cells and tracked their activity in real time using fluorescence microscopy. We find that the activity of two retroelements “the human retrotransposon LINE-1 and bacterial group II intron Ll.LtrB” are lethal to bacterial cell growth, and we reveal the retroelement dynamics that may have played a role in the early evolution of eukaryotes. We also show that the bacterial transposon family IS200/IS605 and its associated protein TnpB may have played a major role in the evolution of adaptive immunity in bacteria. TnpB is a putative ancestor to Cas12 and Cas9, proteins involved in bacterial defense mechanisms against phages. TnpB is carried by the IS200/IS605 family of transposons and we determine that TnpB increases transposon retention. Hence, this mutually beneficial collaboration may explain the prevalence of TnpB in bacterial genomes, creating the necessary conditions for the appropriation of TnpB’s RNA-guided endonuclease activity for adaptive immunity. These studies highlight the importance of investigating the role of transposable element activity in the emergence of complex life.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Physics

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2022

Author dc:creator

• Kaur, Davneet

Contributors dc:contributor

• Kuhlman, Thomas E
• Goldenfeld, Nigel
• Kuehn, Seppe
• Cooper, Lance

• Biophysics
• Transposable Elements
• Transposons
• Rna-guided Endonucleases

Statement dc:rights

• © 2022 Davneet Kaur

Language dc:language

en, eng

Handle dc:identifier

https://hdl.handle.net/2142/117662

OAI record oai:identifier

https://www.ideals.illinois.edu/oai-pmh?verb=GetRecord&metadataPrefix=etdms&identifier=oai%3Awww.ideals.illinois.edu%3A2142%2F117662