Protein flexibility is required for vesicle tethering at the Golgi

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Abstract

The Golgi is decorated with coiled-coil proteins that may extend long distances to help vesicles find their targets. GCC185 is a trans Golgi-associated protein that captures vesicles inbound from late endosomes. Although predicted to be relatively rigid and highly extended, we show that flexibility in a central region is required for GCC185's ability to function in a vesicle tethering cycle. Proximity ligation experiments show that that GCC185's N-and C-termini are within <40nm of each other on the Golgi. In physiological buffers without fixatives, atomic force microscopy reveals that GCC185 is shorter than predicted, and its flexibility is due to a central bubble that represents local unwinding of specific sequences. Moreover, 85% of the N-termini are splayed, and the splayed N-terminus can capture transport vesicles in vitro. These unexpected features support a model in which GCC185 collapses onto the Golgi surface, perhaps by binding to Rab GTPases, to mediate vesicle tethering.

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Pak-yan Patricia Cheung

Department of Biochemistry, Stanford University School of Medicine, Stanford, United States

Competing interests
No competing interests declared.
Charles Limouse

Department of Applied Physics, Stanford University, Stanford, United States

Competing interests
No competing interests declared.
Hideo Mabuchi

Department of Applied Physics, Stanford University, Stanford, United States

Competing interests
No competing interests declared.
Suzanne R Pfeffer

Department of Biochemistry, Stanford University School of Medicine, Stanford, United States

For correspondence
pfeffer@stanford.edu

Competing interests
Suzanne R Pfeffer, Reviewing editor, eLife.

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