title: Sas-4 provides a scaffold for cytoplasmic complexes and tethers them in a centrosome.
abstract: Centrosomes are conserved organelles that are essential for accurate cell division and cilium formation. A centrosome consists of a pair of centrioles surrounded by a protein network of pericentriolar material (PCM) that is essential for the centrosome's function. In this study, we show that Sas-4 provides a scaffold for cytoplasmic complexes (named S-CAP), which include CNN, Asl and D-PLP, proteins that are all found in the centrosomes at the vicinity of the centriole. When Sas-4 is absent, nascent procentrioles are unstable and lack PCM, and functional centrosomes are not generated. When Sas-4 is mutated, so that it cannot form S-CAP complexes, centrosomes are present but with dramatically reduced levels of PCM. Finally, purified S-CAP complexes or recombinant Sas-4 can bind centrosomes stripped of PCM, whereas recombinant CNN or Asl cannot. In summary, PCM assembly begins in the cytosol where Sas-4 provides a scaffold for pre-assembled cytoplasmic complexes before tethering of the complexes in a centrosome.
authors.affiliation: Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115, USA.
authors.forename: Jayachandran
authors.initials: J
authors.lastname: Gopalakrishnan
authors.forename: Vito
authors.initials: V
authors.lastname: Mennella
authors.forename: Stephanie
authors.initials: S
authors.lastname: Blachon
authors.forename: Bo
authors.initials: B
authors.lastname: Zhai
authors.forename: Andrew H
authors.initials: AH
authors.lastname: Smith
authors.forename: Timothy L
authors.initials: TL
authors.lastname: Megraw
authors.forename: Daniela
authors.initials: D
authors.lastname: Nicastro
authors.forename: Steven P
authors.initials: SP
authors.lastname: Gygi
authors.forename: David A
authors.initials: DA
authors.lastname: Agard
authors.forename: Tomer
authors.initials: T
authors.lastname: Avidor-Reiss
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D015153:Blotting, Western; D018385:Centrosome / Q000737:chemistry / Q000378:metabolism*; D002853:Chromatography, Liquid; D003593:Cytoplasm / Q000378:metabolism*; D004330:Drosophila; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli; D005455:Fluorescent Antibody Technique; D046911:Macromolecular Substances / Q000737:chemistry / Q000378:metabolism*; D016253:Microscopy, Immunoelectron; D008869:Microtubule-Associated Proteins; D008958:Models, Molecular; D053719:Tandem Mass Spectrometry; D014404:Tubulin / Q000378:metabolism
chemical_list: D029721:Drosophila Proteins; D046911:Macromolecular Substances; D008869:Microtubule-Associated Proteins; C522063:Sas-4 protein, Drosophila; D014404:Tubulin