RT Journal Article
SR Electronic
T1 Structure of the <em>Legionella</em> Dot/Icm type IV secretion system <em>in situ</em> by electron cryotomography
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 085977
DO 10.1101/085977
A1 Debnath Ghosal
A1 Yi-Wei Chang
A1 Kwangcheol C. Jeong
A1 Joseph P. Vogel
A1 Grant J. Jensen
YR 2016
UL http://biorxiv.org/content/early/2016/11/07/085977.abstract
AB Type IV secretion systems (T4SSs) are large macromolecular machines that translocate protein and DNA and are involved in the pathogenesis of multiple human diseases. Here, using electron cryotomography (ECT), we report the in situ structure of the Dot/Icm type IVB secretion system (T4BSS) utilized by the human pathogen Legionella pneumophila. This is the first structure of a type IVB secretion system, and also the first structure of any T4SS in situ. While the Dot/Icm system shares almost no sequence homology with type IVA secretion systems (T4ASSs), its overall structure shows remarkable similarities to two previously imaged T4ASSs, suggesting shared aspects of mechanism. However, compared to one of these, the negative-stain reconstruction of the purified T4ASS from the R388 plasmid, it is approximately twice as long and wide and exhibits several additional large densities, reflecting type-specific elaborations and potentially better structural preservation in situ.