Genetically separable functions of the MEC-17 tubulin acetyltransferase affect microtubule organization.
BACKGROUND
Microtubules (MTs) are formed from the lateral association of 11-16 protofilament chains of tubulin dimers, with most cells containing 13-protofilament (13-p) MTs. How these different MTs are formed is unknown, although the number of protofilaments may depend on the nature of the α- and β-tubulins.


RESULTS
Here we show that the enzymatic activity of the Caenorhabiditis elegans α-tubulin acetyltransferase (α-TAT) MEC-17 allows the production of 15-p MTs in the touch receptor neurons (TRNs) MTs. Without MEC-17, MTs with between 11 and 15 protofilaments are seen. Loss of this enzymatic activity also changes the number and organization of the TRN MTs and affects TRN axonal morphology. In contrast, enzymatically inactive MEC-17 is sufficient for touch sensitivity and proper process outgrowth without correcting the MT defects. Thus, in addition to demonstrating that MEC-17 is required for MT structure and organization, our results suggest that the large number of 15-p MTs, normally found in the TRNs, is not essential for mechanosensation.


CONCLUSIONS
These experiments reveal a specific role for α-TAT in the formation of MTs and in the production of higher order MTs arrays. In addition, our results indicate that the α-TAT protein has functions that require acetyltransferase activity (such as the determination of protofilament number) and others that do not (presence of internal MT structures).
Department of Biological Sciences, Columbia University, New York, NY 10027, USA.
Irini
I
Topalidou
Charles
C
Keller
Nereo
N
Kalebic
Ken C Q
KC
Nguyen
Hannah
H
Somhegyi
Kristin A
KA
Politi
Paul
P
Heppenstall
David H
DH
Hall
Martin
M
Chalfie
D000107:Acetylation; D000123:Acetyltransferases / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D017173:Caenorhabditis elegans; D029742:Caenorhabditis elegans Proteins / Q000235:genetics / Q000378:metabolism*; D003078:Colchicine; D017404:In Situ Hybridization, Fluorescence; D008465:Mechanoreceptors / Q000378:metabolism*; D008854:Microscopy, Electron; D008870:Microtubules / Q000201:enzymology* / Q000502:physiology* / Q000648:ultrastructure; D009154:Mutation / Q000235:genetics; D014404:Tubulin / Q000378:metabolism*
D029742:Caenorhabditis elegans Proteins; C118234:MEC-12 protein, C elegans; D014404:Tubulin; D000123:Acetyltransferases; C552528:MEC-17 protein, C elegans; D003078:Colchicine