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

J Cell Sci. 1999 Feb;112 ( Pt 3):395-403.

Abstract

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 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*

Substances

  • Caenorhabditis elegans Proteins
  • Helminth Proteins
  • MEC-12 protein, C elegans
  • Mec-7 protein, C elegans
  • Tubulin