Pseudouridine synthase 7 is an opportunistic enzyme that binds and modifies substrates with diverse sequences and structures
Meredith K. Purchal, Daniel E. Eyler, Mehmet Tardu, Monika K. Franco, Megan M. Korn, Taslima Khan, Ryan McNassor, Rachel Giles, Katherine Lev, Hari Sharma, Jeremy Monroe, Leena Mallik, Markos Koutmos, Kristin S. Koutmou
Abstract
Significance Pseudouridine is among the most-abundant RNA modifications. We present a framework for conceptualizing how eukaryotic pseudouridine synthases select their substrates. This work reveals the structure of yeast pseudouridine synthase 7 (Pus7) and presents cell-based and biochemical investigations of enzyme binding and activity. We demonstrate that Pus7 interacts promiscuously with RNAs containing UG U AR sequences. Our observations raise the question of why these enzymes only modify <5% of UG U AR sequences in the transcriptome, suggesting that factors beyond inherent enzyme properties—such as protein localization, local RNA structure, and RNA–protein interactions—principally shape Pus7 substrate selection. These findings support a role for Pus7 in providing cells with a mechanism to rapidly alter protein synthesis in response to cellular conditions.