The pathogenic R5L mutation disrupts formation of Tau complexes on the microtubule by altering local N-terminal structure

Significance The microtubule-associated protein Tau is strongly linked to a number of neurological diseases. Disease onset is typically associated with weakened interaction with the microtubule, but this widely accepted model is based on hyperphosphorylation or mutations within the C-terminal microtubule-binding domain of Tau. Here, we find that an N-terminal disease-associated mutation in Tau, R5L, does not reduce Tau affinity for microtubules but instead, modifies the N-terminal structure, altering Tau’s behavior and ability to condense on the microtubule surface. Our findings challenge the current paradigms of both how mutations in Tau lead to disease and the functional role of the N-terminal region of Tau.