MEC-12, an alpha-tubulin required for touch sensitivity in C. elegans

• Published in: Journal of cell science Vol. 112 ( Pt 3); no. 3; pp. 395 - 403
• Main Authors: Fukushige, T, Siddiqui, Z K, Chou, M, Culotti, J G, Gogonea, C B, Siddiqui, S S, Hamelin, M
• Format: Journal Article
• Language: English
• Published: England 01.02.1999
• Subjects: Acetylation; Amino Acid Sequence; Animals; Blotting, Northern; Caenorhabditis elegans - anatomy & histology; Caenorhabditis elegans - metabolism; Caenorhabditis elegans - physiology; Caenorhabditis elegans Proteins; Fluorescent Antibody Technique, Indirect; Helminth Proteins - metabolism; Microtubules - metabolism; Molecular Sequence Data; Point Mutation; Polymorphism, Restriction Fragment Length; Touch - physiology; Tubulin - metabolism
• ISSN: 0021-9533; 1477-9137
• DOI: 10.1242/jcs.112.3.395

mec-12 is one of a dozen genes required for touch receptor neuron function in Caenorhabditis elegans. Some mec-12 mutants (mechanosensory-defective) lack the large-diameter microtubules that are characteristic of these neurons (15 protofilaments, as opposed to 11). Mutants of mec-7, a alpha-tubulin encoding gene, have a similar phenotype. We have identified the nature of mec-12 by germline transformation rescue and characterization of a point mutation. Sequence analysis of the mec-12 encoded product (MEC-12) indicates that it corresponds to a novel C. elegans alpha-tubulin. MEC-12 is the only identified C. elegans alpha-tubulin that contains a lysine at position 40, a known site of post-translational acetylation. Some mec-12 mutations eliminate microtubule acetylation as assayed immunocyto-chemically; phenotypic rescue using a MEC-12 variant lacking the lysine-40 showed that acetylation is not required for MEC-12 activity. Although functionally needed only in the touch neurons, mec-12 is expressed in several other neuron types. These results support the notion that tubulin isotype diversity contributes to the formation of distinct classes of microtubules; 15-protofilament microtubule assembly requires MEC-12 alpha-tubulin and MEC-7 beta-tubulin, which are both highly expressed in the touch receptor neurons. MEC-12 is the first reported alpha-tubulin isotype that appears to be required in a single class of neuronal microtubules.