Structures of SAS-6 Suggest Its Organization in Centrioles

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Science  27 Jan 2011:
DOI: 10.1126/science.1199325


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.