Role of Senataxins in resolving transcription-replication conflicts

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Complete, accurate genome replication is essential for life. Our long-term goal is to determine how cells faithfully complete genome replication. However, a major potential obstacle to the replication apparatus is transcription. Although cells possess efficient pathways that process transcription-replication conflicts, these protective mechanisms are not well understood. In this project, we will determine the function of disease-associated Senataxin proteins to the resolution of transcription-replication conflicts.

Senataxin is a DNA/RNA translocase-helicase with multiple roles in nucleic acid metabolism, including in transcription termination and replication fork progression. S. pombe has two Senataxin orthologs, Sen1 and Dbl8. In preliminary data, we have observed that when each of the two Senataxin homologs are mutated, significant replication arrest occurs within some gene bodies. First, we will test whether R-loops are causative of the transcription-replication conflicts we see in the absence of Senataxins. Second, we will establish whether the transcription-replication conflict resolution function of Senataxins is conserved in S. cerevisiae. Our preliminary data indicate that high levels of transcription are necessary, but not sufficient, to cause fork arrest in the absence of Senataxins. Therefore, third, we will establish the sequence features that cause fork arrest in the absence of Senataxins. Recent work has shown that Senataxin associates with the replication fork. Thus, fourth, we will determine if this fork association is required for Senataxins ability to resolve transcription-replication conflicts. Finally, we will use structurally informed mutations to elucidate molecular models for how Senataxins resolve T-R conflicts. Together, these experiments will provide unprecedented mechanistic insight into how disease-relevant traits of Senataxins counteract transcription-replication conflicts to maintain genome stability.