Autogenous Translational Regulation of the Borna Disease Virus Negative Control Factor X from Polycistronic mRNA Using Host RNA Helicases

PLoS Pathogens

Kazuyoshi Ikuta¹  Yohei Hayashi¹  Naohiro Ohtaki¹  Yohei Watanabe¹  Keizo Tomonaga² 

[1] Department of Virology, Research Institute for Microbial Diseases (BIKEN), Osaka University, Suita, Osaka, Japan;Section of Viral Infections, Thailand–Japan Research Collaboration Center on Emerging and Re-emerging Infections (RCC-ERI), Nonthaburi, Thailand

关键词: Messenger RNA;    Protein translation;    Untranslated regions;    Gene prediction;    Immunoprecipitation;    RNA extraction;    Phosphorylation;    Plasmid construction;   

DOI  :  10.1371/journal.ppat.1000654

学科分类：生物科学（综合）

来源: Public Library of Science

【 摘 要 】

Borna disease virus (BDV) is a nonsegmented, negative-strand RNA virus that employs several unique strategies for gene expression. The shortest transcript of BDV, X/P mRNA, encodes at least three open reading frames (ORFs): upstream ORF (uORF), X, and P in the 5′ to 3′ direction. The X is a negative regulator of viral polymerase activity, while the P phosphoprotein is a necessary cofactor of the polymerase complex, suggesting that the translation of X is controlled rigorously, depending on viral replication. However, the translation mechanism used by the X/P polycistronic mRNA has not been determined in detail. Here we demonstrate that the X/P mRNA autogenously regulates the translation of X via interaction with host factors. Transient transfection of cDNA clones corresponding to the X/P mRNA revealed that the X ORF is translated predominantly by uORF-termination-coupled reinitiation, the efficiency of which is upregulated by expression of P. We found that P may enhance ribosomal reinitiation at the X ORF by inhibition of the interaction of the DEAD-box RNA helicase DDX21 with the 5′ untranslated region of X/P mRNA, via interference with its phosphorylation. Our results not only demonstrate a unique translational control of viral regulatory protein, but also elucidate a previously unknown mechanism of regulation of polycistronic mRNA translation using RNA helicases.

【 授权许可】

CC BY