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The dimeric Golgi protein Gorab binds to Sas6 as a monomer to mediate centriole duplication.

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Fatalska, Agnieszka  ORCID logo
Stepinac, Emma 
Richter, Magdalena 
Kovacs, Levente 
Pietras, Zbigniew 


The duplication and ninefold symmetry of the Drosophila centriole requires that the cartwheel molecule, Sas6, physically associates with Gorab, a trans-Golgi component. How Gorab achieves these disparate associations is unclear. Here, we use hydrogen-deuterium exchange mass spectrometry to define Gorab's interacting surfaces that mediate its subcellular localization. We identify a core stabilization sequence within Gorab's C-terminal coiled-coil domain that enables homodimerization, binding to Rab6, and thereby trans-Golgi localization. By contrast, part of the Gorab monomer's coiled-coil domain undergoes an antiparallel interaction with a segment of the parallel coiled-coil dimer of Sas6. This stable heterotrimeric complex can be visualized by electron microscopy. Mutation of a single leucine residue in Sas6's Gorab-binding domain generates a Sas6 variant with a sixteenfold reduced binding affinity for Gorab that cannot support centriole duplication. Thus, Gorab dimers at the Golgi exist in equilibrium with Sas6-associated monomers at the centriole to balance Gorab's dual role.



D. melanogaster, Golgi, Gorab, Rab6, Sas6, cell biology, centriole duplication, molecular biophysics, structural biology, Animals, Centrioles, Drosophila Proteins, Drosophila melanogaster, Golgi Matrix Proteins, Larva, Mutation

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eLife Sciences Publications, Ltd
Wellcome Trust (Investigator Award)
National Institute of Neurological Disorders and Stroke (R01NS113930)
National Science Centre (MAESTRO (UMO-2014/14/A/NZ1/00306))
Austrian Science Fund (P28231-B28)
National Institute of Neurological Disorders and Stroke (W-1258 Doktoratskollegs)