SPN1 IS A KEY PLAYER IN TRANSCRIPTION THROUGH ITS DYNAMIC INTERACTION NETWORK

Abstract

Transcription is a fundamental cellular process that relies on the coordinated activity of numerous proteins to ensure proper synthesis of RNA strands. This process involves both essential proteins, which are required for cell viability, and non-essential proteins. Essential proteins that function in transcription include Spn1, Spt5, Spt6, and RNAPII. Spn1 is a known histone and nucleosome-binding protein, though its role in transcription remains poorly understood. This thesis explores Spn1’s role in transcription using a combination of in vitro and in vivo approaches. Mapping published cryo-EM structures identified predicted binding interfaces on Spn1 with RNAPII, Spt5, and Spt6. Binding surfaces between Spn1 and Spt5, particularly the highly conserved loop and cavity, were found to be critical for viability. Although the Spn1-RNAPII predicted interaction surface was not essential, Spn1 and RNAPII demonstrated high-affinity binding in vitro. Further analysis of Spn1’s genetic interactions with non-essential transcription factors identified surfaces on Spn1 that are vital for the transcriptional elongation complex.