J Virol. 2019 Jan 9. pii: JVI.02161-18. doi: 10.1128/JVI.02161-18. [Epub ahead of print]
RNA-Binding Motif Protein 24 (RBM24) Is Involved in pgRNA Packaging by Mediating Interaction between HBV Polymerase and the Epsilon Element.
Yao Y1,2, Yang B1,2, Chen Y3,4, Wang H3,4, Hu X3, Zhou Y3, Gao X5, Lu M6, Niu J5, Wen Z1, Wu C7, Chen X8.
Author information
1
Joint Center of Translational Precision Medicine, Guangzhou Institute of Pediatrics, Guangzhou Women and Children Medical Center, Guangzhou, China.
2
Joint Center of Translational Precision Medicine, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China.
3
Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China.
4
University of Chinese Academy of Sciences, Beijing, China.
5
Department of Hepatology, The First Hospital of Jilin University, Changchun, Jilin, China.
6
Institute of Virology, University Hospital of Essen, Essen, Germany.
7
Joint Center of Translational Precision Medicine, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China [email protected].
8
Joint Center of Translational Precision Medicine, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China [email protected].
Abstract
Encapsidation of pregenome RNA (pgRNA) is a curial step in HBV replication. Binding by viral polymerase (Pol) to the epsilon stem loop (ε) on the 5' terminal region (TR) of pgRNA is required for pgRNA packaging. However, the detailed mechanism is not well understood. RNA-binding motif protein 24 (RBM24) inhibits core translation by binding to the 5' TR of pgRNA. Here, we demonstrate that RBM24 is also involved in pgRNA packaging. RBM24 directly binds to the lower bulge of ε via RNA recognition submotifs (RNPs). RBM24 also interacts with Pol in an RNA-independent manner. The alanine-rich domain (ARD) of RBM24 and the reverse transcriptase domain (RT) of Pol are essential for binding between RBM24 and Pol. In addition, overexpression of RBM24 increases Pol-ε interaction, whereas RBM24 knockdown decreases interaction. RBM24 was able to rescue binding between ε and mutant Pol lacking ε-binding activity, further showing that RBM24 mediates interaction between Pol and ε by forming a Pol-RBM24-ε complex. Finally, RBM24 significantly promotes the packaging efficiency of pgRNA. In conclusion, RBM24 mediates Pol-ε interaction and formation of a Pol-RBM24-ε complex, which inhibits translation of pgRNA and results in pgRNA packing into capsids/virions for reverse transcription and DNA synthesis.IMPORTANCE Hepatitis B virus (HBV) is a ubiquitous human pathogen, and HBV infection is a major global health burden. Chronic HBV infection is associated with the development of liver diseases including fulminant hepatitis, hepatic fibrosis, cirrhosis, and hepatocellular carcinoma. A currently approved vaccine can prevent HBV infection, and medications are able to reduce viral load and prevent liver disease progression. However, current treatments rarely achieve a cure for chronic infection. Thus, it is important to gain insight into the mechanisms of HBV replication. In this study, we found that the host factor RBM24 is involved in pregenomic RNA (pgRNA) packaging and regulates HBV replication. These findings highlight a potential target for antiviral therapeutics of HBV infection.