Crystal structures of Uso1 membrane tether reveal an alternative conformation in the globular head domain

Yoonyoung Heo,Hye-Jin Yoon,Hyung Ho Lee,Hanseo Ko,Soonmin Jang

doi:10.1038/s41598-020-66480-1

Yoonyoung Heo, Hye-Jin Yoon + Show 3 more

Open Access

https://doi.org/10.1038/s41598-020-66480-1

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Journal: Scientific Reports	Publication Date: Jun 12, 2020
Citations: 7	License type: open-access

Affiliation: Seoul National University, Sejong University

Abstract

Membrane tethers play a critical role in organizing the complex molecular architecture of eukaryotic cells. Uso1 (yeast homolog of human p115) is essential for tethering in vesicle transport from ER to Golgi and interacts with Ypt1 GTPase. The N-terminal globular head domain of Uso1 is responsible for Ypt1 binding; however, the mechanism of tethering between ER transport vesicles and Golgi is unknown. Here, we determined two crystal structures for the Uso1 N-terminal head domain in two alternative conformations. The head domain of Uso1 exists as a monomer, as confirmed using size-exclusion chromatography coupled to multi-angle light scattering and analytical gel filtration. Although Uso1 consists of a right-handed α-solenoid, like that in mammalian homologs, the overall conformations of both Uso1 structures were not similar to previously known p115 structures, suggesting that it adopts alternative conformations. We found that the N- and C-terminal regions of the Uso1 head domain are connected by a long flexible linker, which may mediate conformational changes. To analyse the role of the alternative conformations of Uso1, we performed molecular docking of Uso1 with Ypt1, followed by a structural comparison. Taken together, we hypothesize that the alternative conformations of Uso1 regulate the precise docking of vesicles to Golgi.

Highlights

Uso[1] is composed of 1,790 amino acids, which form a dimer with an N-terminal globular head, followed by a parallel coiled-coil[16]
Previous structural studies on the globular head domain of p115 revealed that it exists as a homodimer and exhibits an armadillo-fold that is decorated by elongated loops[17,18]
It is interesting to note that the collapse of the rod shape of EEA1, a coiled-coil tether, is regulated by the binding of the Rab5-GTP complex, where the hinge region is essential for correct vesicle trafficking from endoplasmic reticulum (ER) to Golgi[19]

Summary

Introduction

Uso[1] is composed of 1,790 amino acids, which form a dimer with an N-terminal globular head, followed by a parallel coiled-coil[16]. To understand how Uso[1] interacts with Ypt1-GTP, we performed structural analysis of the N-terminal globular head region of Uso[1] (Uso1GHR). Biochemical studies including size-exclusion chromatography coupled to multi-angle light scattering (SEC-MALS), analytical gel filtration, and molecular docking showed that the alternative conformations of Uso1GHR are inappropriate for dimerization and should adapt to its partner via its degree of flexibility, providing insights into the regulation of Uso[1] for precise vesicle tethering from ER to Golgi.

Results

Conclusion