University of Illinois Urbana-Champaign

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

Kaur, Davneet

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

Description

Title
Revealing the transposable element dynamics driving evolutionary transitions through direct observation in live cells
Author(s)
Kaur, Davneet
Issue Date
2022-11-30
Director of Research (if dissertation) or Advisor (if thesis)
Kuhlman, Thomas E
Doctoral Committee Chair(s)
Goldenfeld, Nigel
Committee Member(s)
  • Kuehn, Seppe
  • Cooper, Lance
Department of Study
Physics
Discipline
Physics
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Biophysics, Transposable Elements, Transposons, RNA-guided endonucleases
Abstract
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.
Graduation Semester
2022-12
Type of Resource
Thesis
Copyright and License Information
© 2022 Davneet Kaur

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