Cellular interactome dynamics during heat stress

Quantitative in vivo cross-linking-mass spectrometry was used to identify significant time-dependent interactome changes that occur prior to large-scale proteome abundance remodeling in cells subjected to heat stress. Interactome changes were identified within minutes of applied heat stress, including changes in chaperone systems as expected due to altered functional demand. Global analysis of all interactome changes revealed the largest significant enrichment in the class of RNA binding proteins, providing new time-dependent conformational insight on complex relationships that exist between transcription, translation and cellular stress response mechanisms upstream of transcriptional reprogramming. Observed interactome dynamics of RNA binding proteins that are also HSP90 clients constitute mechanistic changes that increase HSP90 functional demand, evident from observed HSP90 interactome changes early in heat stress. However, these changes together with observed heat stress-induced ATP level reduction result in observed complex time-dependent HSP90 interactome dynamics, indicating HSP90 conformational bottleneck formation with increased stress duration.