title: The homo-oligomerisation of both Sas-6 and Ana2 is required for efficient centriole assembly in flies.
abstract: 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.
authors.affiliation: Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom.
authors.forename: Matthew A
authors.initials: MA
authors.lastname: Cottee
authors.affiliation: Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom.
authors.forename: Nadine
authors.initials: N
authors.lastname: Muschalik
authors.affiliation: Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom.
authors.forename: Steven
authors.initials: S
authors.lastname: Johnson
authors.affiliation: Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom.
authors.forename: Joanna
authors.initials: J
authors.lastname: Leveson
authors.affiliation: Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom.
authors.forename: Jordan W
authors.initials: JW
authors.lastname: Raff
authors.affiliation: Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom.
authors.forename: Susan M
authors.initials: SM
authors.lastname: Lea
mesh_terms: D000818:Animals; D018797:Cell Cycle Proteins / Q000378:metabolism*; D002502:Centrioles / Q000378:metabolism*; D018360:Crystallography, X-Ray; D004252:DNA Mutational Analysis; D029721:Drosophila Proteins / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000502:physiology*; D008869:Microtubule-Associated Proteins / Q000378:metabolism*; D017354:Point Mutation; D011487:Protein Conformation; D055503:Protein Multimerization
chemical_list: C547835:Ana2 protein, Drosophila; D018797:Cell Cycle Proteins; D029721:Drosophila Proteins; D008869:Microtubule-Associated Proteins; C522062:Sas-6 protein, Drosophila
keywords: Ana2; D. melanogaster; SAS-6; STIL; biophysics; cell biology; centriole; centrosome; human; structural biology; ultra-high resolution structure