What is it about?

Nucleosome tethering is a common mechanism used by viruses to attenuate host DNA-damage-response (DDR) signals and orchestrate viral life cycles. The Epstein-Barr virus tegument protein BKRF4 interacts with histone H2A–H2B via a histone chaperone-like sequence. The “triple-anchor” binding mode and a DWP motif confers BKRF4 a stronger H2A–H2B binding than many other H2A–H2B chaperones. Strikingly, BKRF4 only binds nucleosomes when they are partially disassembled and accumulates at DNA breaks, where chromatin needs to be disassembled prior to repair. Our findings reveal a histone chaperone mimicry strategy used by viruses to inhibit host DDR signaling.

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Why is it important?

This study reveals how BKRF4 bindings to the partially unfolded nucleosome and elucidates an unconventional mechanism of host antiviral signal attenuation.

Perspectives

The virus attempts to manipulate host cellular machinery to inactivate the immune system of host cells. Although histone binding proteins have been widely used by host cells to regulate chromatin structure, the functional role of viral proteins interacting with host histones remains enigmatic. Our recent study shows that Epstein-Barr virus uses a histone chaperone mimicry strategy to inhibit host antiviral responses. Studying the interplay between viruses and host chromatin will help to dissect the role of these proteins in the life cycle of viruses.

Zheng Zhou
Institute of Biophysics, Chinese Academy of Sciences

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This page is a summary of: Epstein-Barr virus protein BKRF4 restricts nucleosome assembly to suppress host antiviral responses, Proceedings of the National Academy of Sciences, September 2022, Proceedings of the National Academy of Sciences, DOI: 10.1073/pnas.2203782119.
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