title: The phosphorylation state of an aurora-like kinase marks the length of growing flagella in Chlamydomonas.
abstract: Flagella and cilia are structurally polarized organelles whose lengths are precisely defined, and alterations in length are related to several human disorders. Intraflagellar transport (IFT) and protein signaling molecules are implicated in specifying flagellar and ciliary length, but evidence has been lacking for a flagellum and cilium length sensor that could participate in active length control or establishment of structural polarity. Previously, we showed that the phosphorylation state of the aurora-like protein kinase CALK in Chlamydomonas is a marker of the absence of flagella. Here we show that CALK phosphorylation state is also a marker for flagellar length. CALK is phosphorylated in cells without flagella, and during flagellar assembly it becomes dephosphorylated. Dephosphorylation is not simply a consequence of initiation of flagellar assembly or of time after experimentally induced flagellar loss, but instead requires flagella to be assembled to a threshold length. Analysis of cells with flagella of varying lengths shows that the threshold length for CALK dephosphorylation is ~6 μm (half length). Studies with short and long flagellar mutants indicate that cells detect absolute rather than relative flagellar length. Our results demonstrate that cells possess a mechanism for translating flagellar length into a posttranslational modification of a known flagellar regulatory protein.
authors: Protein Science Laboratory of the Ministry of Education, School of Life Sciences, Tsinghua University, Beijing 100084, China.
authors: Minna
authors: M
authors: Luo
authors: Muqing
authors: M
authors: Cao
authors: Yinan
authors: Y
authors: Kan
authors: Guihua
authors: G
authors: Li
authors: William
authors: W
authors: Snell
authors: Junmin
authors: J
authors: Pan
mesh_terms: D064127:Aurora Kinases; D019521:Body Patterning; D002696:Chlamydomonas / Q000737:chemistry / Q000254:growth & development* / Q000378:metabolism* / Q000648:ultrastructure; D005407:Flagella / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*; D015151:Immunoblotting; D010766:Phosphorylation; D010940:Plant Proteins / Q000378:metabolism; D011499:Protein Processing, Post-Translational; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D015398:Signal Transduction
chemical_list: D010940:Plant Proteins; D064127:Aurora Kinases; D017346:Protein Serine-Threonine Kinases