In:
eLife, eLife Sciences Publications, Ltd, Vol. 4 ( 2015-05-21)
Abstract:
Gram-negative bacteria can cause serious diseases in humans, such as cholera and bacterial meningitis. These bacteria are surrounded by two membranes: an inner membrane and an outer membrane. Proteins called secretins are components of several large molecular complexes that are embedded within the outer membrane. Some secretin-containing complexes form pores in the bacterial membranes and allow molecules to pass in or out of the cell. Some secretins also form part of the machinery that allow Gram-negative bacteria to grow fibre-like structures called type IV pili. These pili help bacteria that cause infections to move and stick to host cells, where they can also trigger massive changes in the host cells' architecture. Multiple copies of a secretin protein called PilQ form a channel in the outer membrane of the bacteria that allows a type IV pilus to grow out of the surface of the cell. The pilus can then hook the bacteria onto surfaces and other cells. There is evidence to suggest the type IV pilus machinery is involved in the uptake of DNA from other bacteria, an important but poorly understood process that has contributed to the spread of multi-drug resistance. Now, Gold et al. have used a cutting-edge technique called ‘electron cryo-tomography’ to analyse the three-dimensional structure of the machinery that builds the type IV pili in the membranes of a bacterium called Thermus thermophilus. This analysis revealed that, similar to many other channel complexes, the PilQ channel can be ‘open’ or ‘closed’. When pili are absent, the channel is closed, but the channel opens when pili are present. Further analysis also revealed the structure of an assembled pilus. Next, Gold et al. studied the open state of the type IV pilus in more detail and observed that a region of each of the PilQ proteins moves a considerable distance to make way for the pilus to enter the central pore. These results will pave the way for future studies of type IV pili and other secretin-containing complexes and underpin efforts to investigate new drug targets to combat bacterial infections.
Type of Medium:
Online Resource
ISSN:
2050-084X
DOI:
10.7554/eLife.07380.001
DOI:
10.7554/eLife.07380.002
DOI:
10.7554/eLife.07380.003
DOI:
10.7554/eLife.07380.004
DOI:
10.7554/eLife.07380.005
DOI:
10.7554/eLife.07380.006
DOI:
10.7554/eLife.07380.007
DOI:
10.7554/eLife.07380.008
DOI:
10.7554/eLife.07380.009
DOI:
10.7554/eLife.07380.010
DOI:
10.7554/eLife.07380.011
DOI:
10.7554/eLife.07380.012
DOI:
10.7554/eLife.07380.013
Language:
English
Publisher:
eLife Sciences Publications, Ltd
Publication Date:
2015
detail.hit.zdb_id:
2687154-3
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