Journal Article

Conserved TCP domain of Sas-4/CPAP is essential for pericentriolar material tethering during centrosome biogenesis

Yang, Qian, Gopalakrishnan, Jay, Šarić, Tomo, Wason, Arpit, Debec, Alain, Poser, Ina, Zhang, Xingrun, Pozniakovsky, Andrei, Basiri, Marcus L., Gabriel, Elke, Avidor-Reiss, Tomer, Zheng, Xiangdong, Mehrjardi, Narges Zare, Hyman, Anthony A., Li, Haitao, Gooi, Li Ming

2014

Overview

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.

• Publisher: National Academy of Sciences
• Subject: Animals / Animals, Genetically Modified / biogenesis / Biological Sciences / Biosynthesis / Biotechnology / brain / Brain - pathology / Cell Biology / Cells / centrioles / Centrioles - metabolism / Centrosome - metabolism / Computer Science / Crystal structure / Cytoplasm / Cytoplasm - metabolism / Deregulation / Development Biology / Drosophila / Drosophila melanogaster - metabolism / Drosophila Proteins - metabolism / Humans / Induced Pluripotent Stem Cells - cytology / Insects / Life Sciences / Male / Microcephaly - genetics / Models, Molecular / mutants / Mutation / PNAS Plus / Point Mutation / Protein Binding / Protein Structure, Secondary / Protein Structure, Tertiary / protein-protein interactions / Proteins / Stem cells / Testis - metabolism