Heat Shock Protein 90 Ensures the Integrity of Rubella Virus p150 Protein and Supports Viral Replication

Abstract

Two viral nonstructural proteins, p150 and p90, are expressed in rubella virus (RUBV)-infected cells and mediate viral genome replication, presumably using various host machineries. Molecular chaperones are critical host factors for the maintenance of cellular proteostasis, and certain viral proteins use this chaperone system. The RUBV p150 and p90 proteins are generated from a precursor polyprotein, p200, via processing by the protease activity of its p150 region. This processing is essential for RUBV genome replication. Here we show that heat shock protein 90 (HSP90), a molecular chaperone, is an important host factor for RUBV genome replication. The treatment of RUBV-infected cells with the HSP90 inhibitors 17-allylamino-17-desmethoxygeldanamycin (17-AAG) and ganetespib suppressed RUBV genome replication. HSP90α physically interacted with p150, but not p90. Further analyses into the mechanism of action of the HSP90 inhibitors revealed that HSP90 activity contributes to p150 functional integrity and promotes p200 processing. Collectively, our data demonstrate that RUBV p150 is a client of the HSP90 molecular chaperone and that HSP90 functions as a key host factor for RUBV replication. IMPORTANCE Accumulating evidence indicates that RNA viruses use numerous host factors during replication of their genomes. However, the host factors involved in rubella virus (RUBV) genome replication are largely unknown. In this study, we demonstrate that the HSP90 molecular chaperone is needed for the efficient replication of the RUBV genome. Further, we reveal that HSP90 interacts with RUBV nonstructural protein p150 and its precursor polyprotein, p200. HSP90 contributes to the stability of p150 and the processing of p200 via its protease domain in the p150 region. We conclude that the cellular molecular chaperone HSP90 is a key host factor for functional maturation of nonstructural proteins for RUBV genome replication. These findings provide novel insight into this host-virus interaction.

HSP90AB1 is a host factor that promotes porcine deltacoronavirus replication

“…Viral proteins, such as p150 of rubella virus ( 39 ), VP5 protein of pseudorabies virus ( 40 ), neuraminidase protein of influenza A virus ( 41 ), and N protein of MERS-CoV ( 29 ), are HSP90 client proteins, and HSP90 is required for maintaining their stability. Moreover, the interaction of HSP90 and client proteins can facilitate viral infection by regulating various cellular signaling pathways ( 42 , 43 ).…”

“…In addition to protein kinases and transcription factors, numerous viral proteins are identified as HSP90 client proteins, which can be degraded via the proteasome or autophagy pathway ( 39 , 41 , 50 ). Considering this, we utilized a specific proteasome inhibitor, MG-132, and autophagy inhibitor, chloroquine, to evaluate whether the decrease in N protein levels in infected KO cells and HSP90AB1-inhibited cells was the result of protein degradation through one of these pathways.…”

Identification of Inhibitors and Drug Targets for Human Adenovirus Infections

“…However, many other inhibitors were reported to inhibit a panel of DNA and RNA viruses ( Supplemental Tables S1–S4 ). For example, HSP90 inhibitor STA-9090 inhibits EBV, RUBV, HPV [ 32 , 33 , 34 ], and 17-AAG inhibits 16 different types of viruses, including Ebola viruses and coronaviruses ( Supplemental Table S1 ) [ 35 , 36 ]. An mTOR inhibitor, Torin 2, can inhibit the replication of 10 viruses, including SARS-CoV-2 ( Supplemental Table S2 ) [ 37 , 38 ].…”

Membrane Sphingomyelin in Host Cells Is Essential for Nucleocapsid Penetration into the Cytoplasm after Hemifusion during Rubella Virus Entry

“…Monolayers of cells were inoculated with the SINV M2215 strain at an MOI of 4. The supernatants were harvested at 0, 8, 22, or 32 h after inoculation at 37°C, and the infectious titers were determined by a plaque-forming assay using BHK cells, as described previously ( 63 , 64 ). NT1 or SMS1KO22 cells were inoculated with the MeV IC323/Ed-H-EGFP strain at an MOI of 0.1.…”