Dynamic Capture and Release of Endoplasmic Reticulum Exit Sites by Golgi Stacks in Arabidopsis.

Ikuko Hara-Nishimura,Yoshitaka Kimori,Tomoo Shimada,Junpei Takagi

doi:10.1016/j.isci.2020.101265

Ikuko Hara-Nishimura, Yoshitaka Kimori + Show 2 more

Open Access

https://doi.org/10.1016/j.isci.2020.101265

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Abstract

SummaryProtein transport from the endoplasmic reticulum (ER) to Golgi stacks is mediated by the coat protein complex COPII, which is assembled at an ER subdomain called ER exit site (ERES). However, the dynamic relationship between ERESs and Golgi stacks is unknown. Here, we propose a dynamic capture-and-release model of ERESs by Golgi stacks in Arabidopsis thaliana. Using variable-angle epifluorescence microscopy with high-temporal-resolution imaging, COPII-component-bound ERESs were detected as punctate structures with sizes of 300–500 nm. Some punctate ERESs are distributed on ER tubules and sheet rims, whereas others gather around a Golgi stack in an ER-network cavity to form a beaded-ring structure. Free ERESs that wander into an ER cavity are captured by a Golgi stack in a cytoskeleton-independent manner. Then, they are released by the Golgi stack for recycling. The dynamic ERES cycling might contribute to efficient transfer of de novo synthesized cargo proteins from the ER to Golgi stacks.

Highlights

Protein transport from the endoplasmic reticulum (ER) to Golgi stacks is mediated by the coat protein complex II (COPII) machinery (Brandizzi and Barlowe, 2013)
SUMMARY Protein transport from the endoplasmic reticulum (ER) to Golgi stacks is mediated by the coat protein complex COPII, which is assembled at an ER subdomain called ER exit site (ERES)
Some punctate ERESs are distributed on ER tubules and sheet rims, whereas others gather around a Golgi stack in an ER-network cavity to form a beadedring structure

Summary

Introduction

Protein transport from the endoplasmic reticulum (ER) to Golgi stacks is mediated by the coat protein complex II (COPII) machinery (Brandizzi and Barlowe, 2013). COPII vesicles bud off ERESs and fuse with Golgi stacks to transfer cargo proteins (Brandizzi and Barlowe, 2013). In Saccharomyces cerevisiae, in which ERESs are not always located adjacent to Golgi stacks, cis-Golgi cisternae transiently come in contact with ERESs for COPII-dependent cargo transfer (Kurokawa et al, 2014). This result emphasizes the need for Golgi-stack contact with ERESs for the accurate transport of cargo proteins. Even though many studies have examined ER-Golgi cargo transport, the dynamic relationship between ERESs and Golgi stacks remains unknown

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