PRMT5: A novel regulator of Hepatitis B virus replication and an arginine methylase of HBV core

Abstract

In mammals, protein arginine methyltransferase 5, PRMT5, is the main type II enzyme responsible for the majority of symmetric dimethylarginine formation in polypeptides. Recent study reported that PRMT5 restricts Hepatitis B virus (HBV) replication through epigenetic repression of HBV DNA transcription and interference with encapsidation of pregenomic RNA. Here we demonstrate that PRMT5 interacts with the HBV core (HBc) protein and dimethylates arginine residues within the arginine-rich domain (ARD) of the carboxyl-terminus. ARD consists of four arginine rich subdomains, ARDI, ARDII, ARDIII and ARDIV. Mutation analysis of ARDs revealed that arginine methylation of HBc required the wild-type status of both ARDI and ARDII. Mass spectrometry analysis of HBc identified multiple potential ubiquitination, methylation and phosphorylation sites, out of which lysine K7 and arginines R150 (within ARDI) and R156 (outside ARDs) were shown to be modified by ubiquitination and methylation, respectively. The HBc symmetric dimethylation appeared to be linked to serine phosphorylation and nuclear import of HBc protein. Conversely, the monomethylated HBc retained in the cytoplasm. Thus, overexpression of PRMT5 led to increased nuclear accumulation of HBc, and vice versa, down-regulation of PRMT5 resulted in reduced levels of HBc in nuclei of transfected cells. In summary, we identified PRMT5 as a potent controller of HBc cell trafficking and function and described two novel types of HBc post-translational modifications (PTMs), arginine methylation and ubiquitination.

Expression of quasi-equivalence and capsid dimorphism in the Hepadnaviridae

“…It is worth noting that residue M66 is located in helix 3 adjacent to the hinge region between helix 4a and helix 4b, which is bounded by residues T91 and K96. K96 is highly conserved across genotypes A, B, C, and D, is a key ubiquitination site involved in interactions with the surface antigen, and it appears to be involved in conformational changes between RNA-and DNA-containing capsids and therefore capsid maturation and nucleocytoplasmic trafficking [56][57][58]. Notably, this region of the sequence is also very different in the core antigen of the non-enveloped fish viruses (see section on phylogeny).…”

Hepatitis B Virus Subverts the Autophagy Elongation Complex Atg5-12/16L1 and Does Not Require Atg8/LC3 Lipidation for Viral Maturation

“…To probe for cell lysis, the supernatants of transfected cells were assayed for LDH activity (n ϭ 2). ylated, core species (27) and/or the precore protein. The precore protein is identical to core, save for its N-terminal ER signal sequence, composed of 29 residues, that directs precore to the ER, where 19 amino acids are cleaved off from the N terminus (10).…”

Post-translational Modification Control of HBV Biological Processes

“…Moreover, the interaction between PRMT5 and HBc was also demonstrated by CoIP assay in Huh7 cells ( Zhang et al, 2017 ). Several months later, a group from the Czech Republic showed that PRMT5 not only interacts with HBc, but that PRMT3 also weakly binds with HBc by GST pull-down assay from HEK293T cells ( Lubyova et al, 2017 ). They also found that HBc is methylated on its arginine residues at the C-terminal, with the R150 and R156 methylated sites being detected by mass spectrometry ( Lubyova et al, 2017 ).…”

“…Several months later, a group from the Czech Republic showed that PRMT5 not only interacts with HBc, but that PRMT3 also weakly binds with HBc by GST pull-down assay from HEK293T cells ( Lubyova et al, 2017 ). They also found that HBc is methylated on its arginine residues at the C-terminal, with the R150 and R156 methylated sites being detected by mass spectrometry ( Lubyova et al, 2017 ). The potential effect of arginine methylation in HBc is referred to as a regulator for controlling HBc binding to cellular factors, which participate in HBc shuttling between the nucleus and cytoplasm ( Lubyova et al, 2017 ).…”