Assembly of Weibel–Palade body-like tubules from N-terminal domains of von Willebrand factor

doi:10.1073/pnas.0710079105

Assembly of Weibel–Palade body-like tubules from N-terminal domains of von Willebrand factor

*Howard Hughes Medical Institute and
Departments of ^‡Cell Biology and
^§Medicine, Washington University School of Medicine, St. Louis, MO 63110; and
^†Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA 22908

Edited by David Ginsburg, University of Michigan Medical School, Ann Arbor, MI, and approved November 27, 2007 (received for review October 23, 2007)

Abstract

Endothelial cells assemble von Willebrand factor (VWF) multimers into ordered tubules within storage organelles called Weibel–Palade bodies, and tubular packing is necessary for the secretion of VWF filaments that can bind connective tissue and recruit platelets to sites of vascular injury. We now have recreated VWF tubule assembly in vitro, starting with only pure VWF propeptide (domains D1D2) and disulfide-linked dimers of adjacent N-terminal D′D3 domains. Assembly requires low pH and calcium ions and is reversed at neutral pH. Quick-freeze deep-etch electron microscopy and three-dimensional reconstruction of negatively stained images show that tubules contain a repeating unit of one D′D3 dimer and two propeptides arranged in a right-handed helix with 4.2 units per turn. The symmetry and location of interdomain contacts suggest that decreasing pH along the secretory pathway coordinates the disulfide-linked assembly of VWF multimers with their tubular packaging.

Footnotes

^¶To whom correspondence should be addressed at:
Howard Hughes Medical Institute, Washington University School of Medicine, 660 South Euclid Avenue, P.O. Box 8022, St. Louis, MO 63110.
E-mail: esadler{at}im.wustl.edu
Author contributions: R.-H.H., Y.W., J.E.H., E.H.E., and J.E.S. designed research; R.-H.H., Y.W., R.R., X.Y., A.R.P., and J.E.H. performed research; R.-H.H., Y.W., J.E.H., E.H.E., and J.E.S. analyzed data; and R.-H.H. and J.E.S. wrote the paper.
The authors declare no conflict of interest.
This article is a PNAS Direct Submission.
This article contains supporting information online at www.pnas.org/cgi/content/full/0710079105/DC1.
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