Structural analyses of an RNA stability element interacting with poly(A)
Seyed‐Fakhreddin Torabi, Yen-Lin Chen, Kaiming Zhang, Jimin Wang, Suzanne J. DeGregorio, Anand T. Vaidya, Zhaoming Su, Suzette A. Pabit, Wah Chiu, Lois Pollack, Joan A. Steitz
Abstract
Significance RNA triple helices were characterized in vitro over 60 y ago, but only recently implicated in diverse biological activities. The element for nuclear expression (ENE) protects RNA from degradation via triplex formation with the poly(A) tail on the 3ʹ ends of cellular RNAs. ENEs appear in diverse genomes, including a category containing two ENEs separated by a double-stranded region (dENEs). Using structure probing, SAXS, and cryo-EM, we show that poly(A) binding to a rice dENE induces local conformational changes, like formation of a motif that protects the extreme 3ʹ end of the poly(A). These analyses support the relevance of the recent crystal structure of the dENE+poly(A) complex and demonstrate the applicability of other techniques for understanding relatively small RNA structures.