Arabidopsis Pumilio protein APUM5 suppresses Cucumber mosaic virus infection via direct binding of viral RNAs

• Published in: Proceedings of the National Academy of Sciences - PNAS 2013-01, Vol.110 (2), p.779-784
• Main Authors: Huh, Sung Un, Kim, Min Jung, Paek, Kyung-Hee
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Arabidopsis - genetics; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; Base Sequence; Binding sites; Biological Sciences; Blotting, Southern; Cucumovirus - genetics; Cucumovirus - metabolism; Defense mechanisms; Drosophila; Electrophoretic Mobility Shift Assay; Enzyme-Linked Immunosorbent Assay; Flowers & plants; Gene expression; Gene expression regulation; Gene Expression Regulation, Plant - genetics; Genomes; Glucuronidase - metabolism; Histological Techniques; Immunoprecipitation; Infections; Messenger RNA; Molecular Sequence Data; Mutation; Plant Diseases - immunology; Plant Diseases - virology; Protoplasts; Real-Time Polymerase Chain Reaction; Repressor Proteins - genetics; Repressor Proteins - metabolism; RNA; RNA, Viral - metabolism; RNA-Binding Proteins - genetics; RNA-Binding Proteins - metabolism; RNA-protein interactions; Sequence Analysis, DNA; Species Specificity; Transgenic plants; Untranslated regions; Viruses
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.1214287110

Posttranscriptional/translational regulation of gene expression is mediated by diverse RNA binding proteins and plays an important role in development and defense processes. Among the RNA-binding proteins, the mammalian Pumilio RNA-binding family (Puf) acts as posttranscriptional and translational repressors. An Arabidopsis Puf mutant, apum5 - D , was isolated during a T-DNA insertional mutant screen for mutants with reduced susceptibility to Cucumber mosaic virus (CMV) infection. Interestingly, CMV RNA contained putative Pumilio-homology domain binding motifs in its 3′ untranslated region (UTR) and internal places in its genome. APUM5 directly bound to the 3′ UTR motifs and some internal binding motifs in CMV RNAs in vitro and in vivo. We showed that APUM5 acts as a translational repressor that regulates the 3′ UTR of CMV and affects CMV replication. This study uncovered a unique defense system that Arabidopsis APUM5 specifically regulates CMV infection by the direct binding of CMV RNAs.