2026-09-21T13:48:54Z https://www.ideals.illinois.edu/oai-pmh

oai:www.ideals.illinois.edu:2142/117662 2023-07-11 col_2142_5131 col_2142_8859 com_2142_5130 com_2142_8858 com_2142_234

Kuhlman, Thomas E Goldenfeld, Nigel Kuehn, Seppe Cooper, Lance 2022-12 application/pdf en text Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2024-12-01 The student, Davneet Kaur, accepted the attached license on 2022-11-28 at 16:38. The student, Davneet Kaur, submitted this Dissertation for approval on 2022-11-28 at 16:49. This Dissertation was approved for publication on 2022-11-30 at 12:51. DSpace SAF Submission Ingestion Package generated from Vireo submission #18655 on 2023-04-12 at 08:11:38 Revealing the transposable element dynamics driving evolutionary transitions through direct observation in live cells Kaur, Davneet 2022-11-30 Biophysics Transposable Elements Transposons Rna-guided Endonucleases 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. Thesis eng https://hdl.handle.net/2142/117662 © 2022 Davneet Kaur Ph.D. Dissertation Physics University of Illinois at Urbana-Champaign Physics