The HBV Core Protein and Core Particle Both Bind to the PPiase Par14 and Par17 to Enhance Their Stabilities and HBV Replication

Umar Saeed; Zahra Zahid Piracha; Hyeonjoong Kwon; Jumi Kim; Fadia Kalsoom; Yong-Joon Chwae; Sun Park; Ho-Joon Shin; Hyun Woong Lee; Jin Hong Lim; Kyongmin Kim

doi:10.3389/fmicb.2021.795047

The HBV Core Protein and Core Particle Both Bind to the PPiase Par14 and Par17 to Enhance Their Stabilities and HBV Replication

Front Microbiol. 2021 Dec 14:12:795047. doi: 10.3389/fmicb.2021.795047. eCollection 2021.

Authors

Umar Saeed^{1

2}, Zahra Zahid Piracha^{1

2}, Hyeonjoong Kwon^{1

2}, Jumi Kim^{1

2}, Fadia Kalsoom^{1

2}, Yong-Joon Chwae^{1

2}, Sun Park^{1

2}, Ho-Joon Shin^{1

2}, Hyun Woong Lee³, Jin Hong Lim⁴, Kyongmin Kim^{1

2}

Affiliations

¹ Department of Microbiology, Ajou University School of Medicine, Suwon, South Korea.
² Department of Biomedical Science, Graduate School of Ajou University, Suwon, South Korea.
³ Department of Internal Medicine, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, South Korea.
⁴ Department of General Surgery, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, South Korea.

Abstract

We recently reported that the PPIase Par14 and Par17 encoded by PIN4 upregulate HBV replication in an HBx-dependent manner by binding to conserved arginine-proline (RP) motifs of HBx. HBV core protein (HBc) has a conserved ¹³³RP¹³⁴ motif; therefore, we investigated whether Par14/Par17 bind to HBc and/or core particles. Native agarose gel electrophoresis (NAGE) and immunoblotting and co-immunoprecipitation were used. Chromatin immunoprecipitation from HBV-infected HepG2-hNTCP-C9 cells was performed. NAGE and immunoblotting revealed that Par14/Par17 bound to core particles and co-immunoprecipitation revealed that Par14/Par17 interacted with core particle assembly-defective, and dimer-positive HBc-Y132A. Thus, core particles and HBc interact with Par14/Par17. Par14/Par17 interacted with the HBc ¹³³RP¹³⁴ motif possibly via substrate-binding E46/D74 and E71/D99 motifs. Although Par14/Par17 dissociated from core particles upon heat treatment, they were detected in 0.2 N NaOH-treated opened-up core particles, demonstrating that Par14/Par17 bind outside and inside core particles. Furthermore, these interactions enhanced the stabilities of HBc and core particles. Like HBc-Y132A, HBc-R133D and HBc-R133E were core particle assembly-defective and dimer-positive, demonstrating that a negatively charged residue at position 133 cannot be tolerated for particle assembly. Although positively charged R133 is solely important for Par14/17 interactions, the ¹³³RP¹³⁴ motif is important for efficient HBV replication. Chromatin immunoprecipitation from HBV-infected cells revealed that the S19 and E46/D74 residues of Par14 and S44 and E71/D99 residues of Par17 were involved in recruitment of ¹³³RP¹³⁴ motif-containing HBc into cccDNA. Our results demonstrate that interactions of HBc, Par14/Par17, and cccDNA in the nucleus and core particle-Par14/Par17 interactions in the cytoplasm are important for HBV replication.

Keywords: HBV replication study; Hepatitis B virus; PPIase activity; parvulin 14; parvulin 17.