HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: rna.1007408v1 14/6/1201    most recent Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Nallagatla, S. R. Articles by Bevilacqua, P. C. PubMed PubMed Citation Articles by Nallagatla, S. R. Articles by Bevilacqua, P. C. Social Bookmarking                   What's this?

Nucleoside modifications modulate activation of the protein kinase PKR in an RNA structure-specific manner

Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, USA

The human interferon-induced protein kinase PKR is a key component of innate immunity, a process in which it senses pathogenic RNA. PKR consists of an N-terminal dsRNA-binding domain (dsRBD) and a C-terminal kinase domain. Upon binding long (>33 base pairs) stretches of pathogenic dsRNA, PKR undergoes autophosphorylation, which activates it to phosphorylate eIF2, leading to inhibition of translation initiation. Many cellular and viral transcripts contain nucleoside modifications, and these could affect PKR activation. For example, a 5'-triphosphate confers the ability of relatively unstructured transcripts to activate PKR. Effects of internal RNA modifications on PKR activation have not been reported. Herein, PKR activation by ssRNA and dsRNA containing internal nucleobase, sugar, and phosphodiester modifications is analyzed. We find that for 5'-triphosphate-containing ssRNA, most base and sugar modifications abrogate activation, although 2'-fluoro-modified ssRNA does not, indicative of a critical role for hydrogen bonding at the ribose sugar. In the case of dsRNA, a more limited set of nucleoside modifications affect PKR activation. Watson–Crick base-pairing is required for activation, and some minor groove modifications abrogate activation while major groove modifications have little effect. Surprisingly, GU wobble pairs also largely abrogate dsRNA-mediated activation when present at modest levels. Modifications to dsRNA that abrogate activation have no significant effect on dsRBD binding, allowing such RNAs to act as inhibitors and suggesting a nonequivalence of binding ability and activation. Overall, the findings indicate that nucleoside modifications and wobble pairing may serve to discriminate self-RNA and pathogenic RNA in innate immunity.

Keywords: modified RNA; PKR activation; RNA folding; translation

CiteULike    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?