Specifically acetylates 'Lys-40' in alpha-tubulin on the lumenal side of microtubules. Promotes microtubule destabilization and accelerates microtubule dynamics; this activity may be independent of acetylation activity. Acetylates alpha-tubulin with a slow enzymatic rate, due to a catalytic site that is not optimized for acetyl transfer. Enters the microtubule through each end and diffuses quickly throughout the lumen of microtubules. Acetylates only long/old microtubules because of its slow acetylation rate since it does not have time to act on dynamically unstable microtubules before the enzyme is released. May be involved in neuron development. Acetylates alpha-tubulin in neurons, but not in cilia. acetyl-CoA + L-lysyl-[alpha-tubulin] = CoA + H(+) + N(6)-acetyl-L-lysyl-[alpha-tubulin] Monomer. Morpholino knockdown of the protein causes developmental defects at 48 hours post-fertilization (hpf), including cilia curved body shape, short body axis, hydrocephalus, small head and small eyes. Morphants often do not respond, or have slow startle response, when probed with a needle, consistent with neuromuscular defects. Belongs to the acetyltransferase ATAT1 family.