Patronin condensation integrates recognition, protection and organization of microtubule minus ends

Abstract

Microtubule minus ends are central to non-centrosomal microtubule organization, yet how their recognition, protection and molecular organization are integrated remains unclear. Here we show that Drosophila Patronin forms dynamic condensates at microtubule minus ends through a prion-like domain (PrLD). PrLD-mediated condensation cooperates with the CKK domain and a second CKK-independent recognition region to convert weak or broadly distributed microtubule-binding activities into persistent minus-end recognition and tracking. Replacing the PrLD with a heterologous phase-separating HNRNPA1 IDR restores minus-end targeting, indicating that condensation capacity rather than PrLD primary sequence is critical. Patronin condensates further form a protective cap that resists minus-end depolymerization and recruit the cytoskeletal regulators Sas-4, Katanin and Ena. Disrupting PrLD multivalency impairs Patronin localization at multiple developmental sites and causes early organismal lethality. Thus, Patronin condensation creates a physiologically essential microtubule minus-end compartment coupling end recognition, stabilization and cytoskeletal organization.