Hilbert M Erat MC Hachet V Guichard P Blank ID Flückiger I Slater L Lowe ED Hatzopoulos GN Steinmetz MO Gönczy P Vakonakis I 2013 Centrioles are evolutionary conserved organelles that give rise to cilia and flagella as well as centrosomes. Centrioles display a characteristic ninefold symmetry imposed by the spindle assembly abnormal protein 6 (SAS-6) family. SAS-6 from Chlamydomonas reinhardtii and Danio rerio was shown to form ninefold symmetric, ring-shaped oligomers in vitro that were similar to the cartwheels observed in vivo during early steps of centriole assembly in most species. Here, we report crystallographic and EM analyses showing that, instead, Caenorhabotis elegans SAS-6 self-assembles into a spiral arrangement. Remarkably, we find that this spiral arrangement is also consistent with ninefold symmetry, suggesting that two distinct SAS-6 oligomerization architectures can direct the same output symmetry. Sequence analysis suggests that SAS-6 spirals are restricted to specific nematodes. This oligomeric arrangement may provide a structural basis for the presence of a central tube instead of a cartwheel during centriole assembly in these species. application/pdf https://sonar.ch/global/documents/115706 eng info:eu-repo/semantics/altIdentifier/doi/10.1073/pnas.1302721110 info:eu-repo/semantics/altIdentifier/pmid/23798409 info:eu-repo/semantics/openAccess Proceedings of the National Academy of Sciences of the United States of America. - 2013 SAS-5 X-ray crystallography centriolar architecture electron microscopy structure Animals Caenorhabditis elegans Caenorhabditis elegans Proteins Cell Cycle Proteins Crystallography, X-Ray Microscopy, Electron Models, Molecular Protein Conformation Caenorhabditis elegans centriolar protein SAS-6 forms a spiral that is consistent with imparting a ninefold symmetry. http://purl.org/coar/resource_type/c_6501