Crystal structure of human polynucleotide phosphorylase: Insights into its domain function in RNA binding and degradation

Chia Liang Lin, Yi Ting Wang, Wei Zen Yang, Yu-Yuan Hsiao, Hanna S. Yuan*

*Corresponding author for this work

Research output: Contribution to journalArticle

29 Scopus citations

Abstract

Human polynucleotide phosphorylase (hPNPase) is a 3′-to-5′ exoribonuclease that degrades specific mRNA and miRNA, and imports RNA into mitochondria, and thus regulates diverse physiological processes, including cellular senescence and homeostasis. However, the RNA-processing mechanism by hPNPase, particularly how RNA is bound via its various domains, remains obscure. Here, we report the crystal structure of an S1 domain-truncated hPNPase at a resolution of 2.1. The trimeric hPNPase has a hexameric ring-like structure formed by six RNase PH domains, capped with a trimeric KH pore. Our biochemical and mutagenesis studies suggest that the S1 domain is not critical for RNA binding, and conversely, that the conserved GXXG motif in the KH domain directly participates in RNA binding in hPNPase. Our studies thus provide structural and functional insights into hPNPase, which uses a KH pore to trap a long RNA 3′ tail that is further delivered into an RNase PH channel for the degradation process. Structural RNA with short 3′ tails are, on the other hand, transported but not digested by hPNPase.

Original languageEnglish
Pages (from-to)4146-4157
Number of pages12
JournalNucleic Acids Research
Volume40
Issue number9
DOIs
StatePublished - 1 May 2012

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