A Mass Spectrometry-Based Interactome Study on Anisomelic Acid and Its Effects on HPV16 E7

Human papillomavirus (HPV)-driven epithelial cancers rely on actions of viral oncoproteins, notably E7, which disrupts cell cycle control through inactivation of the tumor suppressor pRb. While prophylactic vaccines prevent infection, effective therapeutics for existing HPV-associated malignancies remain lacking. Here, we investigate the natural diterpenoid anisomelic acid (AA) and its mechanism of promoting HPV16 E7 degradation. Using cellular thermal shift assay (CETSA), we demonstrate that AA binds to E7, increasing its thermal stability and suggesting a direct molecular interaction. Mass spectrometry-based interactome analysis revealed that AA treatment reshapes the E7 interactome, enriching for E3 ubiquitin ligases (UBR4, TRIP12, TRIM28), the scaffold protein SQSTM1, and HSP40/HSP70 chaperone complexes involved in protein quality control and misfolded protein signaling. These data support a model in which AA binding induces conformational changes in E7 that enhance its recognition by ubiquitin-proteasome and chaperone-mediated degradation pathways. Our findings provide mechanistic insight into AA’s antiviral mode of action and highlight its potential as a lead compound for targeted degradation of HPV oncoproteins.