Protein phosphatase 1 catalyzes HBV core protein dephosphorylation and is co-packaged with viral pregenomic RNA into nucleocapsids

Autoři: Zhanying Hu aff001;  Haiqun Ban aff001;  Haiyan Zheng aff002;  Mingliang Liu aff003;  Jinhong Chang aff001;  Ju-Tao Guo aff001
Působiště autorů: Department of Experimental Medicine, Baruch S. Blumberg Institute, Doylestown, Pennsylvania, United States of America aff001;  Biological mass spectrometry facility, Robert Wood Johnson Medical School and Rutgers, The State University of New Jersey. Piscataway, New Jersey, United States of America aff002;  Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences & Peking Union Medical College, Tian-Tan Xi-Li, Beijing, China aff003
Vyšlo v časopise: Protein phosphatase 1 catalyzes HBV core protein dephosphorylation and is co-packaged with viral pregenomic RNA into nucleocapsids. PLoS Pathog 16(7): e1008669. doi:10.1371/journal.ppat.1008669
Kategorie: Research Article
doi: 10.1371/journal.ppat.1008669


Hepatitis B virus (HBV) replicates its genomic DNA via viral DNA polymerase self-primed reverse transcription of a RNA pre-genome in the nucleocapsid assembled by 120 core protein (Cp) dimers. The arginine-rich carboxyl-terminal domain (CTD) of Cp plays an important role in the selective packaging of viral DNA polymerase-pregenomic (pg) RNA complex into nucleocapsid. Previous studies suggested that the CTD is initially phosphorylated at multiple sites to facilitate viral RNA packaging and subsequently dephosphorylated in association with viral DNA synthesis and secretion of DNA-containing virions. However, our recent studies suggested that Cp is hyper-phosphorylated as free dimers and its dephosphorylation is associated with pgRNA encapsidation. Herein, we provide further genetic and biochemical evidence supporting that extensive Cp dephosphorylation does take place during the assembly of pgRNA-containing nucleocapsids, but not empty capsids. Moreover, we found that cellular protein phosphatase 1 (PP1) is required for Cp dephosphorylation and pgRNA packaging. Interestingly, the PP1 catalytic subunits α and β were packaged into pgRNA-containing nucleocapsids, but not empty capsids, and treatment of HBV replicating cells with core protein allosteric modulators (CpAMs) promoted empty capsid assembly and abrogated the encapsidation of PP1 α and β. Our study thus identified PP1 as a host cellular factor that is co-packaged into HBV nucleocapsids, and plays an essential role in selective packaging of the viral DNA-polymerase-pgRNA complex through catalyzing Cp dephosphorylation.

Klíčová slova:

Capsids – Gel electrophoresis – Immunoprecipitation – Nucleocapsids – Phosphorylation – Viral packaging – Encapsidation – Small interfering RNA


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