van Breugel, M., Hirono, M., Andreeva, A., Yanagisawa, H.A., Yamaguchi, S., Nakazawa, Y., Morgner, N., Petrovich, M., Ebong, I.O., Robinson, C.V., Johnson, C.M., Veprintsev, D., and Zuber, B. (2011) Structures of SAS-6 Suggest Its Organization in Centrioles. Science (New York, N.Y.). 331(6021):1196-1199.
Centrioles are cylindrical, nine-fold 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 N-terminal domain of SAS-6 from zebrafish and 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 likely essential to the structural organization of cartwheel centers.