title: Conserved TCP domain of Sas-4/CPAP is essential for pericentriolar material tethering during centrosome biogenesis.
abstract: Pericentriolar material (PCM) recruitment to centrioles forms a key step in centrosome biogenesis. Deregulation of this process leads to centrosome aberrations causing disorders, one of which is autosomal recessive primary microcephaly (MCPH), a neurodevelopmental disorder where brain size is reduced. During PCM recruitment, the conserved centrosomal protein Sas-4/CPAP/MCPH6, known to play a role in centriole formation, acts as a scaffold for cytoplasmic PCM complexes to bind and then tethers them to centrioles to form functional centrosomes. To understand Sas-4's tethering role, we determined the crystal structure of its T complex protein 10 (TCP) domain displaying a solvent-exposed single-layer of β-sheets fold. This unique feature of the TCP domain suggests that it could provide an "extended surface-like" platform to tether the Sas-4-PCM scaffold to a centriole. Functional studies in Drosophila, human cells, and human induced pluripotent stem cell-derived neural progenitor cells were used to test this hypothesis, where point mutations within the 9-10th β-strands (β9-10 mutants including a MCPH-associated mutation) perturbed PCM tethering while allowing Sas-4/CPAP to scaffold cytoplasmic PCM complexes. Specifically, the Sas-4 β9-10 mutants displayed perturbed interactions with Ana2, a centrosome duplication factor, and Bld-10, a centriole microtubule-binding protein, suggesting a role for the β9-10 surface in mediating protein-protein interactions for efficient Sas-4-PCM scaffold centriole tethering. Hence, we provide possible insights into how centrosomal protein defects result in human MCPH and how Sas-4 proteins act as a vehicle to tether PCM complexes to centrioles independent of its well-known role in centriole duplication.
authors.affiliation: Ministry of Education Key Laboratory of Protein Sciences, Center for Structural Biology, School of Life Sciences, and Department of Basic Medical Sciences, School of Medicine, Tsinghua University, Beijing 100084, People's Republic of China.
authors.forename: Xiangdong
authors.initials: X
authors.lastname: Zheng
authors.forename: Li Ming
authors.initials: LM
authors.lastname: Gooi
authors.forename: Arpit
authors.initials: A
authors.lastname: Wason
authors.forename: Elke
authors.initials: E
authors.lastname: Gabriel
authors.forename: Narges Zare
authors.initials: NZ
authors.lastname: Mehrjardi
authors.forename: Qian
authors.initials: Q
authors.lastname: Yang
authors.forename: Xingrun
authors.initials: X
authors.lastname: Zhang
authors.forename: Alain
authors.initials: A
authors.lastname: Debec
authors.forename: Marcus L
authors.initials: ML
authors.lastname: Basiri
authors.forename: Tomer
authors.initials: T
authors.lastname: Avidor-Reiss
authors.forename: Andrei
authors.initials: A
authors.lastname: Pozniakovsky
authors.forename: Ina
authors.initials: I
authors.lastname: Poser
authors.forename: Tomo
authors.initials: T
authors.lastname: Saric
authors.forename: Anthony A
authors.initials: AA
authors.lastname: Hyman
authors.forename: Haitao
authors.initials: H
authors.lastname: Li
authors.forename: Jay
authors.initials: J
authors.lastname: Gopalakrishnan
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D001921:Brain / Q000473:pathology; D002502:Centrioles / Q000378:metabolism*; D018385:Centrosome / Q000378:metabolism*; D003593:Cytoplasm / Q000378:metabolism; D029721:Drosophila Proteins / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000378:metabolism; D006801:Humans; D057026:Induced Pluripotent Stem Cells / Q000166:cytology; D008297:Male; D008831:Microcephaly / Q000235:genetics; D008869:Microtubule-Associated Proteins; D008958:Models, Molecular; D017354:Point Mutation; D011485:Protein Binding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D013737:Testis / Q000378:metabolism
chemical_list: D029721:Drosophila Proteins; D008869:Microtubule-Associated Proteins; C522063:Sas-4 protein, Drosophila