The dimeric Golgi protein Gorab binds to Sas6 as a monomer to mediate centriole duplication
Abstract
The duplication and 9-fold 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 sub-cellular 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 anti-parallel interaction with a segment of the parallel coiled-coil dimer of Sas6. This stable hetero-trimeric 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 16-fold reduced binding affinity for Gorab that can not support centriole duplication. Thus Gorab dimers at the Golgi exist in equilibrium with Sas-6 associated monomers at the centriole to balance Gorab's dual role.
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All data generated or analysed during this study are included in the manuscript and supporting files.
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Author details
Funding
National Science Centre (MAESTRO (UMO-2014/14/A/NZ1/00306))
- Agnieszka Fatalska
- Michal Dadlez
Wellcome Trust
- Agnieszka Fatalska
- Magdalena Richter
- Levente Kovacs
Austrian Science Fund (P28231-B28)
- Gang Dong
Austrian Science Fund (W-1258 Doktoratskollegs)
- Emma Stepinac
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Copyright
© 2021, Fatalska et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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