Deacetylation of BmHSP90 at Lysines 550/567 Stimulates Its Chaperone Function and Actin Polymerization to Drive the Proliferation of Bombyx mori Nucleopolyhedrovirus

The silkworm, <i>Bombyx mori</i>, is a model organism with significant agricultural and economic importance, but it is threatened by <i>Bombyx mori</i> nucleopolyhedrovirus (BmNPV). A crucial chaperone, heat shock protein 90 (HSP90), can also facilitate the proliferation of viruses, and our previous quantitative acetylome analysis revealed that lysines 550 and 567 in the carboxyl-terminal domain (CTD) of <i>Bombyx mori</i> HSP90 (BmHSP90) were significantly deacetylated following BmNPV infection, but the underlying mechanism remained unknown. In this study, deacetylation-mimetic (K to R) mutants of BmHSP90 exhibited increased dimerization and chaperone activity compared with the wild-type. In addition, the mutants also exhibited higher affinity for actin, promoting F-actin polymerization. Collectively, these changes facilitated BmNPV replication and progeny virion production. This study reveals that the deacetylation of BmHSP90 at K550 and K567 mediates crucial host-virus interactions, providing novel insights into potential antiviral strategies.