Centrioles are microtubule-based organelles crucial for cell division, sensing and motility. In C. elegans, the onset of centriole formation requires notably the proteins SAS-5 and SAS-6, which have functional homologs across eukaryotic evolution. Whereas the molecular architecture of SAS-6 and its role in initiating centriole formation are well understood, the mechanisms by which SAS-5 and its relatives function is unclear. Here, we combine biophysical and structural analysis to uncover the architecture of SAS-5 and examine its functional implications in vivo. Our work reveals that two distinct self-associating domains are necessary to form higher-order oligomers of SAS-5: a trimeric coiled coil and a novel globular dimeric Implico domain. Disruption of either domain leads to centriole duplication failure in worm embryos, indicating that large SAS-5 assemblies are necessary for function in vivo.
- Anthony A Hyman, Max Planck Institute of Molecular Cell Biology and Genetics, Germany
© 2015, Rogala et al.
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