title: Zeta-Tubulin Is a Member of a Conserved Tubulin Module and Is a Component of the Centriolar Basal Foot in Multiciliated Cells.
abstract: There are six members of the tubulin superfamily in eukaryotes. Alpha- and beta-tubulin form a heterodimer that polymerizes to form microtubules, and gamma-tubulin nucleates microtubules as a component of the gamma-tubulin ring complex. Alpha-, beta-, and gamma-tubulin are conserved in all eukaryotes. In contrast, delta- and epsilon-tubulin are conserved in many, but not all, eukaryotes and are associated with centrioles, although their molecular function is unclear. Zeta-tubulin is the sixth and final member of the tubulin superfamily and is largely uncharacterized. We find that zeta-, epsilon-, and delta-tubulin form an evolutionarily co-conserved module, the ZED module, that has been lost at several junctions in eukaryotic evolution and that zeta- and delta-tubulin are evolutionarily interchangeable. Humans lack zeta-tubulin but have delta-tubulin. In Xenopus multiciliated cells, zeta-tubulin is a component of the basal foot, a centriolar appendage that connects centrioles to the apical cytoskeleton, and co-localizes there with epsilon-tubulin. Depletion of zeta-tubulin results in disorganization of centriole distribution and polarity in multiciliated cells. In contrast with multiciliated cells, zeta-tubulin in cycling cells does not localize to centrioles and is associated with the TRiC/CCT cytoplasmic chaperone complex. We conclude that zeta-tubulin facilitates interactions between the centrioles and the apical cytoskeleton as a component of the basal foot in differentiated cells and propose that the ZED tubulins are important for centriole functionalization and orientation of centrioles with respect to cellular polarity axes.
authors.affiliation: Department of Biology, Stanford University, Stanford, CA 94305, USA.
authors.forename: Erin
authors.initials: E
authors.lastname: Turk
authors.affiliation: Department of Molecular Biosciences and Center for Systems and Synthetic Biology, University of Texas at Austin, Austin, TX 78712, USA.
authors.forename: Airon A
authors.initials: AA
authors.lastname: Wills
authors.affiliation: Department of Molecular Biosciences and Center for Systems and Synthetic Biology, University of Texas at Austin, Austin, TX 78712, USA.
authors.forename: Taejoon
authors.initials: T
authors.lastname: Kwon
authors.affiliation: Department of Molecular Biosciences and Center for Systems and Synthetic Biology, University of Texas at Austin, Austin, TX 78712, USA.
authors.forename: Jakub
authors.initials: J
authors.lastname: Sedzinski
authors.affiliation: Department of Molecular Biosciences and Center for Systems and Synthetic Biology, University of Texas at Austin, Austin, TX 78712, USA; Howard Hughes Medical Institute.
authors.forename: John B
authors.initials: JB
authors.lastname: Wallingford
authors.affiliation: Department of Biology, Stanford University, Stanford, CA 94305, USA; Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA. Electronic address: stearns@stanford.edu.
authors.forename: Tim
authors.initials: T
authors.lastname: Stearns
mesh_terms: D000818:Animals; D002502:Centrioles / Q000378:metabolism*; D003599:Cytoskeleton / Q000378:metabolism*; D014404:Tubulin / Q000378:metabolism*; D029867:Xenopus Proteins / Q000378:metabolism*; D014982:Xenopus laevis / Q000502:physiology*
chemical_list: D014404:Tubulin; D029867:Xenopus Proteins