?TAT1 controls longitudinal spreading of acetylation marks from open microtubules extremities.

ABSTRACT: Acetylation of the lysine 40 of ?-tubulin (K40) is a post-translational modification occurring in the lumen of microtubules (MTs) and is controlled by the ?-tubulin acetyl-transferase ?TAT1. How ?TAT1 accesses the lumen and acetylates ?-tubulin there has been an open question. Here, we report that acetylation starts at open ends of MTs and progressively spreads longitudinally from there. We observed acetylation marks at the open ends of in vivo MTs re-growing after a Nocodazole block, and acetylated segments growing in length with time. Bias for MTs extremities was even more pronounced when using non-dynamic MTs extracted from HeLa cells. In contrast, K40 acetylation was mostly uniform along the length of MTs reconstituted from purified tubulin in vitro. Quantitative modelling of luminal diffusion of ?TAT1 suggested that the uniform acetylation pattern observed in vitro is consistent with defects in the MT lattice providing lateral access to the lumen. Indeed, we observed that in vitro MTs are permeable to macromolecules along their shaft while cellular MTs are not. Our results demonstrate ?TAT1 enters the lumen from open extremities and spreads K40 acetylation marks longitudinally along cellular MTs. This mode of tip-directed microtubule acetylation may allow for selective acetylation of subsets of microtubules.

SUBMITTER: Ly N 

PROVIDER: S-EPMC5067677 | biostudies-literature | 2016 Oct

REPOSITORIES: biostudies-literature