Subunit Connectivity, Assembly Determinants and Architecture of the Yeast Exocyst Complex

Nat Struct Mol Biol. 2016 Jan;23(1):59-66. doi: 10.1038/nsmb.3146. Epub 2015 Dec 14.

Abstract

The exocyst is a hetero-octameric complex that has been proposed to serve as the tethering complex for exocytosis, although it remains poorly understood at the molecular level. Here, we purified endogenous exocyst complexes from Saccharomyces cerevisiae and showed that they are stable and consist of all eight subunits with equal stoichiometry. Using a combination of biochemical and auxin induced-degradation experiments in yeast, we mapped the subunit connectivity, identified two stable four-subunit modules within the octamer and demonstrated that several known exocyst-binding partners are not necessary for exocyst assembly and stability. Furthermore, we visualized the structure of the yeast complex by using negative-stain electron microscopy; our results indicate that the exocyst exists predominantly as a stable, octameric complex with an elongated architecture that suggests that the subunits are contiguous helical bundles packed together into a bundle of long rods.

Publication types

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

MeSH terms

  • Exocytosis*
  • Macromolecular Substances / chemistry*
  • Macromolecular Substances / isolation & purification*
  • Macromolecular Substances / ultrastructure
  • Microscopy, Electron, Transmission
  • Protein Binding
  • Protein Stability
  • Protein Structure, Quaternary
  • Saccharomyces cerevisiae / physiology*
  • Vesicular Transport Proteins / chemistry*
  • Vesicular Transport Proteins / isolation & purification*
  • Vesicular Transport Proteins / ultrastructure

Substances

  • Macromolecular Substances
  • Vesicular Transport Proteins