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J Mol Biol. 2014 Jul 15;426(14):2605-16. doi: 10.1016/j.jmb.2014.05.009. Epub 2014 May 17.

Structural and functional characterization of the α-tubulin acetyltransferase MEC-17.

Author information

1
Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA.
2
Howard Hughes Medical Institute, Division of Biology and Biological Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA.
3
Howard Hughes Medical Institute, Division of Biology and Biological Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA. Electronic address: pws@caltech.edu.
4
Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA. Electronic address: hoelz@caltech.edu.

Abstract

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.

KEYWORDS:

C. elegans; X-ray crystallography; mechanosensation; substrate recognition; tubulin acetyltransferase

PMID:
24846647
PMCID:
PMC4259157
DOI:
10.1016/j.jmb.2014.05.009
[Indexed for MEDLINE]
Free PMC Article

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