Evidence That the Adenovirus Single-Stranded DNA Binding Protein Mediates the Assembly of Biomolecular Condensates to Form Viral Replication Compartments

Viruses. 2021 Sep 6;13(9):1778. doi: 10.3390/v13091778.

Abstract

A common viral replication strategy is characterized by the assembly of intracellular compartments that concentrate factors needed for viral replication and simultaneously conceal the viral genome from host-defense mechanisms. Recently, various membrane-less virus-induced compartments and cellular organelles have been shown to represent biomolecular condensates (BMCs) that assemble through liquid-liquid phase separation (LLPS). In the present work, we analyze biophysical properties of intranuclear replication compartments (RCs) induced during human adenovirus (HAdV) infection. The viral ssDNA-binding protein (DBP) is a major component of RCs that contains intrinsically disordered and low complexity proline-rich regions, features shared with proteins that drive phase transitions. Using fluorescence recovery after photobleaching (FRAP) and time-lapse studies in living HAdV-infected cells, we show that DBP-positive RCs display properties of liquid BMCs, which can fuse and divide, and eventually form an intranuclear mesh with less fluid-like features. Moreover, the transient expression of DBP recapitulates the assembly and liquid-like properties of RCs in HAdV-infected cells. These results are of relevance as they indicate that DBP may be a scaffold protein for the assembly of HAdV-RCs and should contribute to future studies on the role of BMCs in virus-host cell interactions.

Keywords: Replication Compartments (RCs); biomolecular condensates (BMCs); human adenovirus type 5 (HAdV-5); liquid-liquid phase separation (LLPS); ssDNA-binding protein (DBP); virus-induced cellular compartmentalization.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenoviridae / genetics
  • Adenoviridae / metabolism*
  • Adenoviridae Infections
  • Adenoviruses, Human / metabolism
  • Biomolecular Condensates*
  • Cell Line
  • DNA-Binding Proteins / chemistry
  • DNA-Binding Proteins / metabolism*
  • Host Microbial Interactions
  • Humans
  • Organelles / virology
  • Protein Domains
  • Viral Proteins / chemistry
  • Viral Proteins / genetics
  • Viral Proteins / metabolism
  • Viral Replication Compartments / physiology*
  • Virus Replication / physiology*

Substances

  • DNA-Binding Proteins
  • Viral Proteins