Polyglycylation occurs through the post-translational addition of a polyglycine peptide to the γ-carboxyl group of glutamic acids near the C terminus of α- and β-tubulin1, and has been found only in cells with axonemes, from protists to humans2,3. In Tetrahymena thermophila, multiple sites of polyglycylation on α-tubulin are dispensable. By contrast, mutating similar sites on β-tubulin has site-specific effects, affecting cell motility and cytokinesis, or resulting in cell death4. Here, we address the lethality of a polyglycylation deficiency in T. thermophila using heterokaryons5. Cells with a lethal mutation in the polyglycylation domain of β-tubulin assembled axonemes that lack the central pair, B-subfibres and the transitional zone of outer microtubules (MTs). Furthermore, an arrest in cytokinesis occurred, and was associated with incomplete severing of cortical MTs positioned near the cleavage furrow. Thus, tubulin polyglycylation is required for the maintenance of some stable microtubular organelles that are all known to be polyglycylated in vivo, but its effects on MTs appear to be organelle-specific.
ASJC Scopus subject areas
- Cell Biology