Structures of SAS-6 suggest its organization in centrioles.
van Breugel M., Hirono M., Andreeva A., Yanagisawa H-A., Yamaguchi S., Nakazawa Y., Morgner N., Petrovich M., Ebong I-O., Robinson CV., Johnson CM., Veprintsev D., Zuber B.
Centrioles are cylindrical, ninefold symmetrical structures with peripheral triplet microtubules strictly required to template cilia and flagella. The highly conserved protein SAS-6 constitutes the center of the cartwheel assembly that scaffolds centrioles early in their biogenesis. We determined the x-ray structure of the amino-terminal domain of SAS-6 from zebrafish, and we show that recombinant SAS-6 self-associates in vitro into assemblies that resemble cartwheel centers. Point mutations are consistent with the notion that centriole formation in vivo depends on the interactions that define the self-assemblies observed here. Thus, these interactions are probably essential to the structural organization of cartwheel centers.