Zeta-Tubulin Is a Member of a Conserved Tubulin Module and Is a Component of the Centriolar Basal Foot in Multiciliated Cells

• Published in: Current biology 2015-08, Vol.25 (16), p.2177-2183
• Main Authors: Turk, Erin, Wills, Airon A., Kwon, Taejoon, Sedzinski, Jakub, Wallingford, John B., Stearns, Tim
• Format: Article
• Language: English
• Subjects: Animals; Centrioles - metabolism; Cytoskeleton - metabolism; Tubulin - metabolism; Xenopus laevis - physiology; Xenopus Proteins - metabolism
• ISSN: 0960-9822; 1879-0445
• DOI: 10.1016/j.cub.2015.06.063

There are six members of the tubulin superfamily in eukaryotes [1]. 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 [2–7]. 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. [Display omitted] •Zeta-, epsilon-, and delta-tubulin form an evolutionarily co-conserved module•Zeta-tubulin localizes to the basal foot in multiciliated cells•Zeta-tubulin participates in cytoskeletal organization in multiciliated cells•Epsilon-tubulin co-localizes with zeta-tubulin to basal feet In this paper, Turk et al. characterize the final member of the tubulin superfamily, zeta-tubulin, in Xenopus. Zeta-, epsilon-, and delta-tubulin form an evolutionarily co-conserved module, the ZED module, that the authors propose is important for centriole functionalization and orientation of centrioles with respect to polarity axes.