Mutations of Tubulin Glycylation Sites Reveal Cross-talk between the C Termini of α- and β-Tubulin and Affect the Ciliary Matrix in Tetrahymena

• Published in: The Journal of biological chemistry Vol. 280; no. 1; pp. 596 - 606
• Main Authors: Redeker, Virginie, Levilliers, Nicolette, Vinolo, Emilie, Rossier, Jean, Jaillard, Danielle, Burnette, Dylan, Gaertig, Jacek, Bré, Marie-Hélène
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 07.01.2005; American Society for Biochemistry and Molecular Biology
• Subjects: Amino Acid Sequence; Animals; Cilia; Cilia - metabolism; Cilia - ultrastructure; Life Sciences; Molecular Motor Proteins; Molecular Sequence Data; Mutation; Paramecium; Paramecium - metabolism; Paramecium - ultrastructure; Protein Processing, Post-Translational; Tetrahymena; Tetrahymena - genetics; Tetrahymena - metabolism; Tetrahymena - ultrastructure; Tubulin; Tubulin - genetics; Tubulin - metabolism
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M408324200

Two types of polymeric post-translational modifications of α/β-tubulin, glycylation and glutamylation, occur widely in cilia and flagella. Their respective cellular functions are poorly understood. Mass spectrometry and immunoblotting showed that two closely related species, the ciliates Tetrahymena and Paramecium, have dramatically different compositions of tubulin post-translational modifications in structurally identical axonemes. Whereas the axonemal tubulin of Paramecium is highly glycylated and has a very low glutamylation content, the axonemal tubulin of Tetrahymena is glycylated and extensively glutamylated. In addition, only the α-tubulin of Tetrahymena undergoes detyrosination. Mutations of the known glycylation sites in Tetrahymena tubulin affected the level of each polymeric modification type in both the mutated and nonmutated subunits, revealing cross-talk between α- and β-tubulin. Ultrastructural analyses of glycylation site mutants uncovered defects in the doublet B-subfiber of axonemes and revealed an accumulation of dense material in the ciliary matrix, reminiscent of intraflagellar transport particles seen by others in Chlamydomonas. We propose that polyglycylation and/or polyglutamylation stabilize the B-subfiber of outer doublets and regulate the intraflagellar transport.