Structural and functional characterization of the α-tubulin acetyltransferase MEC-17.
Tubulin protomers undergo an extensive array of post-translational modifications to tailor microtubules to specific tasks. One such modification, the acetylation of lysine 40 of α-tubulin, located in the lumen of microtubules, is associated with stable, long-living microtubule structures. MEC-17 was recently identified as the acetyltransferase that mediates this event. We have determined the crystal structure of the catalytic core of human MEC-17 in complex with its cofactor acetyl-CoA at 1.7Å resolution. The structure reveals that the MEC-17 core adopts a canonical Gcn5-related N-acetyltransferase (GNAT) fold that is decorated with extensive surface loops. An enzymatic analysis of 33 MEC-17 surface mutants identifies hot-spot residues for catalysis and substrate recognition. A large, evolutionarily conserved hydrophobic surface patch that is critical for enzymatic activity is identified, suggesting that specificity is achieved by interactions with the α-tubulin substrate that extend outside of the modified surface loop. An analysis of MEC-17 mutants in Caenorhabditis elegans shows that enzymatic activity is dispensable for touch sensitivity.
['Davenport|Andrew M|AM|', 'Collins|Leslie N|LN|', 'Chiu|Hui|H|', 'Minor|Paul J|PJ|', 'Sternberg|Paul W|PW|', 'Hoelz|André|A|']
D000105:Acetyl Coenzyme A D000123:Acetyltransferases D000595:Amino Acid Sequence D000818:Animals D017173:Caenorhabditis elegans D029742:Caenorhabditis elegans Proteins D018360:Crystallography, X-Ray D006801:Humans D057927:Hydrophobic and Hydrophilic Interactions D008868:Microtubule Proteins D008969:Molecular Sequence Data D009154:Mutation D011487:Protein Conformation D011994:Recombinant Proteins D017386:Sequence Homology, Amino Acid D014404:Tubulin
substrate recognition C. elegans X-ray crystallography mechanosensation tubulin acetyltransferase