Structure of the Complete, Membrane-assembled COPII Coat Reveals a Complex Interaction Network

Overview

Journal Nat Commun

Specialty Biology

Date 2021 Apr 2

PMID 33795673

Citations 29

Authors

Joshua Hutchings

Viktoriya G Stancheva

Nick R Brown

Alan C M Cheung

Elizabeth A Miller

Giulia Zanetti

Affiliations

Soon will be listed here.

Abstract

COPII mediates Endoplasmic Reticulum to Golgi trafficking of thousands of cargoes. Five essential proteins assemble into a two-layer architecture, with the inner layer thought to regulate coat assembly and cargo recruitment, and the outer coat forming cages assumed to scaffold membrane curvature. Here we visualise the complete, membrane-assembled COPII coat by cryo-electron tomography and subtomogram averaging, revealing the full network of interactions within and between coat layers. We demonstrate the physiological importance of these interactions using genetic and biochemical approaches. Mutagenesis reveals that the inner coat alone can provide membrane remodelling function, with organisational input from the outer coat. These functional roles for the inner and outer coats significantly move away from the current paradigm, which posits membrane curvature derives primarily from the outer coat. We suggest these interactions collectively contribute to coat organisation and membrane curvature, providing a structural framework to understand regulatory mechanisms of COPII trafficking and secretion.

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