title: Reduced tubulin polyglutamylation suppresses flagellar shortness in Chlamydomonas.
abstract: Ciliary length control is an incompletely understood process essential for normal ciliary function. The flagella of Chlamydomonas mutants lacking multiple axonemal dyneins are shorter than normal; previously it was shown that this shortness can be suppressed by the mutation suppressor of shortness 1 (ssh1) via an unknown mechanism. To elucidate this mechanism, we carried out genetic analysis of ssh1 and found that it is a new allele of TPG2 (hereafter tpg2-3), which encodes FAP234 functioning in tubulin polyglutamylation in the axoneme. Similar to the polyglutamylation-deficient mutants tpg1 and tpg2-1, tpg2-3 axonemal tubulin has a greatly reduced level of long polyglutamate side chains. We found that tpg1 and tpg2-1 mutations also promote flagellar elongation in short-flagella mutants, consistent with a polyglutamylation-dependent mechanism of suppression. Double mutants of tpg1 or tpg2-1 and fla10-1, a temperature-sensitive mutant of intraflagellar transport, underwent slower flagellar shortening than fla10-1 at restrictive temperatures, indicating that the rate of tubulin disassembly is decreased in the polyglutamylation-deficient flagella. Moreover, α-tubulin incorporation into the flagellar tips in temporary dikaryons was retarded in polyglutamylation-deficient flagella. These results show that polyglutamylation deficiency stabilizes axonemal microtubules, decelerating axonemal disassembly at the flagellar tip and shifting the axonemal assembly/disassembly balance toward assembly.
authors.affiliation: Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, MA 01655 Department of Biological Sciences, Graduate School of Science, University of Tokyo, Tokyo 113-0033, Japan.
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Kubo
authors.affiliation: Department of Biological Sciences, Graduate School of Science, University of Tokyo, Tokyo 113-0033, Japan.
authors.forename: Masafumi
authors.initials: M
authors.lastname: Hirono
authors.affiliation: Department of Biological Sciences, Graduate School of Science, University of Tokyo, Tokyo 113-0033, Japan.
authors.forename: Takumi
authors.initials: T
authors.lastname: Aikawa
authors.affiliation: Department of Biological Sciences, Graduate School of Science, University of Tokyo, Tokyo 113-0033, Japan Department of Life Science, Faculty of Science, Gakushuin University, Tokyo 171-8588, Japan.
authors.forename: Ritsu
authors.initials: R
authors.lastname: Kamiya
authors.affiliation: Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, MA 01655 george.witman@umassmed.edu.
authors.forename: George B
authors.initials: GB
authors.lastname: Witman
mesh_terms: D056444:Axonemal Dyneins / Q000235:genetics / Q000378:metabolism; D054468:Axoneme / Q000378:metabolism; D002696:Chlamydomonas / Q000166:cytology* / Q000235:genetics / Q000378:metabolism*; D002923:Cilia / Q000378:metabolism; D005407:Flagella / Q000378:metabolism*; D009154:Mutation; D010453:Peptide Synthases / Q000378:metabolism*; D011099:Polyglutamic Acid / Q000378:metabolism; D014404:Tubulin / Q000378:metabolism*
chemical_list: D014404:Tubulin; D011099:Polyglutamic Acid; D056444:Axonemal Dyneins; D010453:Peptide Synthases; C112698:tubulin polyglutamylase