The homo-oligomerisation of both Sas-6 and Ana2 is required for efficient centriole assembly in flies

• Main Authors: Matthew A Cottee, Nadine Muschalik, Steven Johnson, Joanna Leveson, Jordan W Raff, Susan M Lea
• Format: Article
• Language: English
• Published: eLife Sciences Publications Ltd 2015-05-01
• Series: eLife
• Subjects: centriole; centrosome; ultra-high resolution structure; SAS-6; Ana2; STIL
• Online Access: https://elifesciences.org/articles/07236

Sas-6 and Ana2/STIL proteins are required for centriole duplication and the homo-oligomerisation properties of Sas-6 help establish the ninefold symmetry of the central cartwheel that initiates centriole assembly. Ana2/STIL proteins are poorly conserved, but they all contain a predicted Central Coiled-Coil Domain (CCCD). Here we show that the Drosophila Ana2 CCCD forms a tetramer, and we solve its structure to 0.8 Å, revealing that it adopts an unusual parallel-coil topology. We also solve the structure of the Drosophila Sas-6 N-terminal domain to 2.9 Å revealing that it forms higher-order oligomers through canonical interactions. Point mutations that perturb Sas-6 or Ana2 homo-oligomerisation in vitro strongly perturb centriole assembly in vivo. Thus, efficient centriole duplication in flies requires the homo-oligomerisation of both Sas-6 and Ana2, and the Ana2 CCCD tetramer structure provides important information on how these proteins might cooperate to form a cartwheel structure.