Structural basis of the hepatitis B virus X protein in complex with DDB1

H Hiroki Tanaka (Department of Structural Virology, National Institute of Global Health and Medicine, Japan Institute for Health Security) J Joao Diogo Dias (Institut de Génétique Humaine, Laboratoire de Virologie Moléculaire, CNRS Université de Montpellier) B Basile Jay (Institut de Génétique Humaine, Laboratoire de Virologie Moléculaire, CNRS Université de Montpellier) S Shunsuke Kita (Laboratory of Biomolecular Science, and Center for Research and Education on Drug Discovery, Faculty of Pharmaceutical Sciences, Hokkaido University, N13W8, Kitaku, Sapporo 060-8628, Japan) M Mina Sasaki (Laboratory of Biomolecular Science, Faculty of Pharmaceutical Sciences, Hokkaido University) H Hiroyuki Takeda N Naoki Kishimoto S Shunsuke Sasaki (Department of Environmental and Molecular Health Sciences, Faculty of Life Sciences, Kumamoto University) S Shogo Misumi M Masashi Mizokami (Genome Medical Sciences Project, Research Institute, National Center for Global Health and Medicine) C Christine Neuveut (Institut de Génétique Humaine, Laboratoire de Virologie Moléculaire, CNRS Université de Montpellier) T Takashi Sumikama M Mikihiro Shibata K Katsumi Maenaka S Shinichi Machida (Department of Structural Virology, National Institute of Global Health and Medicine, Japan Institute for Health Security)

Abstract

A cure for chronic hepatitis B requires eliminating or permanently silencing covalently closed circular DNA (cccDNA). A pivotal target of this approach is the hepatitis B virus (HBV) X protein (HBx), which is a key factor that promotes transcription from cccDNA. However, the HBx structure remains unsolved. Here, we present the cryoelectron microscopy structure of HBx in complex with DDB1, which is an essential complex for cccDNA transcription. In this structure, hydrophobic interactions within HBx were identified, and mutational analysis highlighted their importance in the HBV life cycle. Our biochemical analysis revealed that the HBx–DDB1 complex directly interacts simultaneously with NSE3, which is a component of the SMC5/6 complex, and Spindlin1. Additionally, HBx–DDB1 complex dynamics were explored via high-speed atomic force microscopy. These findings provide comprehensive insights into the structure and function of HBx in HBV replication.

Article Details

Volume / Issue Vol. 122, Issue 24
Published June 17, 2025
ISSN 0027-8424
Publisher National Academy of Sciences

Authors (15)

H

Hiroki Tanaka

Department of Structural Virology, National Institute of Global Health and Medicine, Japan Institute for Health Security

J

Joao Diogo Dias

Institut de Génétique Humaine, Laboratoire de Virologie Moléculaire, CNRS Université de Montpellier

B

Basile Jay

Institut de Génétique Humaine, Laboratoire de Virologie Moléculaire, CNRS Université de Montpellier

S

Shunsuke Kita

Laboratory of Biomolecular Science, and Center for Research and Education on Drug Discovery, Faculty of Pharmaceutical Sciences, Hokkaido University, N13W8, Kitaku, Sapporo 060-8628, Japan

M

Mina Sasaki

Laboratory of Biomolecular Science, Faculty of Pharmaceutical Sciences, Hokkaido University

H

Hiroyuki Takeda

N

Naoki Kishimoto

S

Shunsuke Sasaki

Department of Environmental and Molecular Health Sciences, Faculty of Life Sciences, Kumamoto University

S

Shogo Misumi

M

Masashi Mizokami

Genome Medical Sciences Project, Research Institute, National Center for Global Health and Medicine

C

Christine Neuveut

Institut de Génétique Humaine, Laboratoire de Virologie Moléculaire, CNRS Université de Montpellier

T

Takashi Sumikama

M

Mikihiro Shibata

K

Katsumi Maenaka

S

Shinichi Machida

Department of Structural Virology, National Institute of Global Health and Medicine, Japan Institute for Health Security