XRN1 is a Species-Specific Virus Restriction Factor in Yeasts

Paul A. Rowley; Brandon Ho; Sarah Bushong; Arlen Johnson; Sara L. Sawyer

The literature suggests that Xrn1p is a widely-utilized restriction factor against 564 viruses, as it has been reported to have activity against mammalian viruses [9,16], yeast 565 viruses [8, 24] , and plant viruses [53] . The potent 5'-3' exonuclease activity of Xrn1p has 566 resulted in viruses developing a rich diversity of strategies to protect their RNAs. For 567 instance, Hepatitis C virus recruits MiR-122 and Ago2 to its 5' UTR to protect its RNA 568 genome from Xrn1p degradation [7, 16] . The yeast single-stranded RNA narnavirus uses 569 a different strategy to protect its 5' terminus, folding its RNA to form a stem-loop 570 structure that prevents Xrn1p degradation [8] . In some cases, viruses even depend on 571 Xrn1p to digest viral RNA in a way that benefits viral replication, for example, preventing proteins that initiate endonucleolytic cleavage of host mRNAs, revealing exposed 5' 578 monophosphates that are substrates for Xrn1p degradation. This is thought to interfere 579 All rights reserved. No reuse allowed without permission.