Updated publication reference for PubMed record(s): 31996674. To understand at molecular level how aggregation of Tau modulates its interactions with proteins we reveal key determinant for derailing Tau protein network. By performing quantitative AP-MS we define a new set of interactors which bind Tau upon fibril formation. These interactors contain disordered regions with a unique amino acidic footprint. Such regions are enriched in positively charged Arginines which can engage aberrant binding to Tau fibrils through their guanidinium group via pi-stacking. We also find that the Hsp90 chaperone stalls formation of Tau fibrils and reshapes their abnormal interactome.