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

Elife. 2021 Mar 11:10:e57241. doi: 10.7554/eLife.57241.


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.

Keywords: D. melanogaster; Golgi; Gorab; Rab6; Sas6; cell biology; centriole duplication; molecular biophysics; structural biology.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Centrioles / genetics*
  • Centrioles / metabolism
  • Drosophila Proteins / genetics*
  • Drosophila Proteins / metabolism
  • Drosophila melanogaster / genetics*
  • Drosophila melanogaster / growth & development
  • Drosophila melanogaster / metabolism
  • Golgi Matrix Proteins / genetics*
  • Golgi Matrix Proteins / metabolism
  • Larva / growth & development
  • Larva / metabolism
  • Mutation


  • Drosophila Proteins
  • Golgi Matrix Proteins
  • Sas-6 protein, Drosophila