Abstract
Proteins of the secretin family form large macromolecular complexes, which assemble in the outer membrane of Gram-negative bacteria. Secretins are major components of type II and III secretion systems and are linked to extrusion of type IV pili (T4P) and to DNA uptake. By electron cryo-tomography of whole T. thermophilus cells, we determined the in situ structure of a T4P molecular machine in the open and the closed state. Comparison reveals a major conformational change whereby the N-terminal domains of the central secretin PilQ shift by ~30 Å, and two periplasmic gates open to make way for pilus extrusion. Furthermore, we determine the structure of the assembled pilus.
Article and author information
Author details
Reviewing Editor
- Stephen C Harrison, Harvard Medical School, Howard Hughes Medical Institute, United States
Publication history
- Received: March 9, 2015
- Accepted: May 20, 2015
- Accepted Manuscript published: May 21, 2015 (version 1)
- Version of Record published: June 12, 2015 (version 2)
Copyright
© 2015, Gold et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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