Complexes of tubulin oligomers and tau form a viscoelastic intervening network cross-bridging microtubules into bundles.

ABSTRACT: The axon-initial-segment (AIS) of mature neurons contains microtubule (MT) fascicles (linear bundles) implicated as retrograde diffusion barriers in the retention of MT-associated protein (MAP) tau inside axons. Tau dysfunction and leakage outside of the axon is associated with neurodegeneration. We report on the structure of steady-state MT bundles in varying concentrations of Mg²⁺ or Ca²⁺ divalent cations in mixtures containing αβ-tubulin, full-length tau, and GTP at 37 °C in a physiological buffer. A concentration-time kinetic phase diagram generated by synchrotron SAXS reveals a wide-spacing MT bundle phase (B_ws), a transient intermediate MT bundle phase (B_int), and a tubulin ring phase. SAXS with TEM of plastic-embedded samples provides evid

SUBMITTER: Kohl PA 

PROVIDER: S-EPMC10943092 | biostudies-literature | 2024 Mar

REPOSITORIES: biostudies-literature