SUMOylation of α-tubulin is a novel modification regulating microtubule dynamics.

Microtubules are regulated by a number of known post-translational modifications on α/β-tubulin to fulfill diverse cellular functions. Here, we showed that SUMOylation is a novel post-translational modification on α-tubulin in vivo and in vitro. The SUMOylation on α-tubulin mainly occurred at Lys 96 (K96), K166, and K304 of soluble α-tubulin and could be removed by SUMO-specific peptidase 1. In vitro experiments showed that tubulin SUMOylation could reduce inter-protofilament interaction, promote microtubule catastrophe, and impede microtubule polymerization. In cells, mutation of the SUMOylation sites on α-tubulin reduced catastrophe frequency and increased the proportion of polymerized α-tubulin, while upregulation of SUMOylation with fusion of SUMO1 reduced α-tubulin assembly into microtubules. Additionally, overexpression of SUMOylation-deficient α-tubulin attenuated the neurite extension in Neuro-2a cells. Thus, SUMOylation on α-tubulin represents a new player in the regulation of microtubule properties.