Download MendeleyStructures of SAS-6 coiled coil hold implications for the polarity of the centriolar cartwheel.
Kantsadi, A.L., Hatzopoulos, G.N., Gonczy, P., Vakonakis, I.(2022) Structure
- PubMed: 35240058
- DOI: https://doi.org/10.1016/j.str.2022.02.005
- Primary Citation of Related Structures:
6YRL, 6YRN, 6YS4, 6Z26 - PubMed Abstract:
Centrioles are eukaryotic organelles that template the formation of cilia and flagella, as well as organize the microtubule network and the mitotic spindle in animal cells. Centrioles have proximal-distal polarity and a 9-fold radial symmetry imparted by a likewise symmetrical central scaffold, the cartwheel. The spindle assembly abnormal protein 6 (SAS-6) self-assembles into 9-fold radially symmetric ring-shaped oligomers that stack via an unknown mechanism to form the cartwheel. Here, we uncover a homo-oligomerization interaction mediated by the coiled-coil domain of SAS-6. Crystallographic structures of Chlamydomonas reinhardtii SAS-6 coiled-coil complexes suggest this interaction is asymmetric, thereby imparting polarity to the cartwheel. Using a cryoelectron microscopy (cryo-EM) reconstitution assay, we demonstrate that amino acid substitutions disrupting this asymmetric association also impair SAS-6 ring stacking. Our work raises the possibility that the asymmetric interaction inherent to SAS-6 coiled-coil provides a polar element for cartwheel assembly, which may assist the establishment of the centriolar proximal-distal axis.
Organizational Affiliation:
Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK.
