ジャーナル: EMBO Rep / 年: 2020 タイトル: Pseudo-repeats in doublecortin make distinct mechanistic contributions to microtubule regulation. 著者: Szymon W Manka / Carolyn A Moores / 要旨: Doublecortin (DCX) is a neuronal microtubule-associated protein (MAP) indispensable for brain development. Its flexibly linked doublecortin (DC) domains-NDC and CDC-mediate microtubule (MT) ...Doublecortin (DCX) is a neuronal microtubule-associated protein (MAP) indispensable for brain development. Its flexibly linked doublecortin (DC) domains-NDC and CDC-mediate microtubule (MT) nucleation and stabilization, but it is unclear how. Using high-resolution time-resolved cryo-EM, we mapped NDC and CDC interactions with tubulin at different MT polymerization stages and studied their functional effects on MT dynamics using TIRF microscopy. Although coupled, each DC repeat within DCX appears to have a distinct role in MT nucleation and stabilization: CDC is a conformationally plastic module that appears to facilitate MT nucleation and stabilize tubulin-tubulin contacts in the nascent MT lattice, while NDC appears to be favored along the mature lattice, providing MT stabilization. Our structures of MT-bound DC domains also explain in unprecedented detail the DCX mutation-related brain defects observed in the clinic. This modular composition of DCX reflects a common design principle among MAPs where pseudo-repeats of tubulin/MT binding elements chaperone or stabilize distinct conformational transitions to regulate distinct stages of MT dynamic instability.
根拠: microscopy, The assembly is a fragment (repeating unit) of a 14-protofilament GDP-microtubule decorated with NDC-NDC chimera via either of the two N-terminal DC repeats of human doublecortin ...根拠: microscopy, The assembly is a fragment (repeating unit) of a 14-protofilament GDP-microtubule decorated with NDC-NDC chimera via either of the two N-terminal DC repeats of human doublecortin (DCX), as determined by Cryo-EM 3D reconstruction
5-component complex of N-terminal DC domain (NDC) of NDC-NDC chimera (human doublecortin sequence) bound to 14-protofilament GDP-microtubule lattice site composed of 4 tubulin subunits (two alpha-subunits and two beta-subunits)