Structural and functional analyses of hepatitis B virus X protein BH3-like domain and Bcl-xL interaction

• Published in: Nature communications Vol. 10; no. 1; pp. 3192 - 14
• Main Authors: Zhang, Tian-Ying, Chen, Hong-Ying, Cao, Jia-Li, Xiong, Hua-Long, Mo, Xiao-Bing, Li, Tian-Liang, Kang, Xiao-Zhen, Zhao, Jing-Hua, Yin, Bo, Zhao, Xiang, Huang, Cheng-Hao, Yuan, Quan, Xue, Ding, Xia, Ning-Shao, Yuan, Y. Adam
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 19.07.2019; Nature Publishing Group; Nature Portfolio
• Subjects: 13/1; 13/51; 14/28; 631/326/596/1550; 631/535/1266; 82/16; Animals; Apoptosis; Apoptosis Regulatory Proteins - chemistry; Bcl-2 protein; Bcl-x protein; bcl-X Protein - chemistry; Binding; Biocompatibility; Crystal structure; Crystallography, X-Ray; Cytotoxicity; Disease Models, Animal; Hep G2 Cells; Hepatitis; Hepatitis B; Hepatitis B virus - genetics; Hepatitis B virus - metabolism; Humanities and Social Sciences; Humans; Hydrophobic and Hydrophilic Interactions; Hydrophobicity; Male; Mice; Mice, Inbred C57BL; Models, Molecular; multidisciplinary; Mutation; Peptides; Protein Binding; Protein Interaction Domains and Motifs; Proteins; Proto-Oncogene Proteins c-bcl-2 - chemistry; Replication; Science; Science (multidisciplinary); Structure-function relationships; Toxicity; Trans-Activators - chemistry; Trans-Activators - genetics; Trans-Activators - physiology; Viral Regulatory and Accessory Proteins; Virus Replication - physiology; Viruses
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-019-11173-1

Hepatitis B virus (HBV) X protein, HBx, interacts with anti-apoptotic Bcl-2 and Bcl-xL proteins through its BH3-like motif to promote HBV replication and cytotoxicity. Here we report the crystal structure of HBx BH3-like motif in complex with Bcl-xL where the BH3-like motif adopts a short α-helix to snuggle into a hydrophobic pocket in Bcl-xL via its noncanonical Trp120 residue and conserved Leu123 residue. This binding pocket is ~2 Å away from the canonical BH3-only binding pocket in structures of Bcl-xL with proapoptotic BH3-only proteins. Mutations altering Trp120 and Leu123 in HBx impair its binding to Bcl-xL in vitro and HBV replication in vivo, confirming the importance of this motif to HBV. A HBx BH3-like peptide, HBx-aa113-135, restores HBV replication from a HBx-null HBV replicon, while a shorter peptide, HBx-aa118-127, inhibits HBV replication. These results provide crucial structural and functional insights into drug designs for inhibiting HBV replication and treating HBV patients. Hepatitis B virus X protein (HBx) binds anti-apoptotic Bcl-xL through its BH3-like motif to promote viral replication. Here, the authors provide the structure of the HBx BH3-like domain and Bcl-xL, which shows an unusual mode of interaction, and identify a short peptide that inhibits HBV replication in cultured human hepatic cells.