Abstract
Hepatitis B virus (HBV) core protein (HBc) plays many roles in the HBV life cycle, such as regulation of transcription, RNA encapsidation, reverse transcription, and viral release. To accomplish these functions, HBc interacts with many host proteins and undergoes different post-translational modifications (PTMs). One of the most common PTMs is ubiquitination, which was shown to change the function, stability, and intracellular localization of different viral proteins, but the role of HBc ubiquitination in the HBV life cycle remains unknown. Here, we found that HBc protein is post-translationally modified through K29-linked ubiquitination. We performed a series of co-immunoprecipitation experiments with wild-type HBc, lysine to arginine HBc mutants and wild-type ubiquitin, single lysine to arginine ubiquitin mutants, or single ubiquitin-accepting lysine constructs. We observed that HBc protein could be modified by ubiquitination in transfected as well as infected hepatoma cells. In addition, ubiquitination predominantly occurred on HBc lysine 7 and the preferred ubiquitin chain linkage was through ubiquitin-K29. Mass spectrometry (MS) analyses detected ubiquitin protein ligase E3 component N-recognin 5 (UBR5) as a potential E3 ubiquitin ligase involved in K29-linked ubiquitination. These findings emphasize that ubiquitination of HBc may play an important role in HBV life cycle.
Highlights
Hepatitis B virus (HBV) is a hepatotropic virus belonging to the Hepadnaviridae family [1]
In contrast to our previous study performed in HepG2-hNTCP [31], the Huh7 cells were used in all co-transfection experiments of HBc with post-translational modifiers and different ubiquitin variants
The stringent conditions were used during cell lysis, co-immunoprecipitation, and washing in order to identify the direct linkage of UBL proteins with tagged HBc [40]
Summary
Hepatitis B virus (HBV) is a hepatotropic virus belonging to the Hepadnaviridae family [1]. The World Health Organization has revealed that an estimated 325 million people worldwide are chronically infected with hepatitis B or C viruses (HBV and HCV). Available treatments, which are based on the application of nucleotide analogues and pegylated interferon, suppress viral replication but are not curative [2]. HBV persists by establishing an episomal covalently closed circular double-stranded DNA (cccDNA) from relaxed circular DNA in the nucleus of infected cells. Cells 2020, 9, 2547 for viral transcription [3,4] and expresses at least six overlapping RNAs transcribed from four open reading frames (ORFs): S, C, P, and X. The S ORF encodes surface envelope proteins (S, M, and L), the
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
