Phosphorylation regulates viral biomolecular condensates to promote infectious progeny production

Biomolecular condensates (BMCs) play important roles in diverse biological processes. Many viruses form BMCs which have been implicated in various functions critical for the productive infection of host cells. The adenovirus L1-52/55 kilodalton protein (52K) was recently shown to form viral BMCs that coordinate viral genome packaging and capsid assembly. Although critical for packaging, we do not know how viral condensates are regulated during adenovirus infection. Here we show that phosphorylation of serine residues 28 and 75 within the N-terminal intrinsically disordered region of 52K modulates viral condensates in vitro and in cells, promoting liquid-like properties. Furthermore, we demonstrate that phosphorylation of 52K promotes viral genome packaging and the production of infectious progeny particles. Collectively, our findings provide insights into how viral condensate properties are regulated and maintained in a state conducive to their function in viral progeny production. In addition, our findings have implications for antiviral strategies aimed at targeting the regulation of viral BMCs to limit viral multiplication. Synopsis An intrinsically disordered region (IDR) of the adenovirus 52 kilodalton protein (52K) is critical for the formation of condensates that facilitate assembly of packaged progeny particles. This work shows that phosphorylation of the IDR regulates condensate properties. Adenovirus 52K is phosphorylated at residues S28 and S75 within its N-terminal IDR. Phosphorylation of the IDR promotes liquid-like condensate properties in cells and in vitro. Phosphorylation increases the number of packaged particles assembled during infection, suggesting that condensate properties are important for their function in viral progeny production. Adenovirus protein 52K is phosphorylated at Ser28 and Ser75 in its intrinsically disordered region, modulating its liquid-like condensate properties.