Tubulin acetyltransferase alpha TAT1 destabilizes microtubules Independently of its acetylation activity

Acetylation ofα-tubulin at lysine 40 (K40) is a well-conserved posttranslational modification that marks long-lived microtubules but has poorly understood functional significance. Recently,αTAT1, a member of the Gcn5-relatedN-acetyltransferase superfamily, has been identified as anF-tubulin acetyltransferase in ciliated organisms. Here, we explored the function ofαTAT1 with the aim of understanding the consequences ofαTAT1-mediated microtubule acetylation.Wedemonstrate thatα-tubulin is the major target of αTAT1 but thatαTAT1 also acetylates itself in a regulatory mechanism that is required for effective modification of tubulin.Wefurther show that in mammalian cells,αTAT1 promotes microtubule destabilization and accelerates microtubule dynamics. Intriguingly, this effect persists in anFTAT1 mutant with no acetyltransferase activity, suggesting that interaction ofαTAT1 with microtubules, rather than acetylation per se, is the critical factor regulating microtubule stability. Our data demonstrate thatαTAT1 has cellular functions that extend beyond its classical enzymatic activity as an α-tubulin acetyltransferase ©2013,American Society for Microbiology.