Thursday, 25 May 2017

Researchers uncover how bacteria burst our cells

Scientists based in Vienna unveil the complex molecular structure that causes lethal infections by Mycobacterium tuberculosis (Mtb). Their findings might have implications for potential therapies against antibiotic-resistant tuberculosis. The researchers have described the overall architecture of an assembly of proteins known as Type VII (T7SS) secretion systems found in a group of bacteria which cause diseases such as tuberculosis.

T7SS-systems play a key role in tuberculosis infections and might present important targets for much needed new drugs: blocking these systems could prevent the bacteria from bursting the host cells and could thus alleviate the infection.

In addition to the core body of T7SS, some of the proteins extend down into the bacterial cell. The team collected Small Angle X-ray Scattering (SAXS) data at the EMBL SAXS beamline on the DESY campus in Hamburg to help understand what they look like and how these parts of the secretion system might move. "We believe these arm-like proteins help to move the molecules of different shapes and sizes from the inside of the bacterial cell towards the pore of the secretion system for them to be transported out of the cell," says first author Kate Beckham from EMBL Hamburg.

Now further biochemical and genetic experiments will be carried out to support the structural data and to provide in vivo insights into the components required for assembly of the T7 secretion system.


Katherine S. H. Beckham, Luciano Ciccarelli, Catalin M. Bunduc, Haydyn D. T. Mertens, Roy Ummels, Wolfgang Lugmayr, Julia Mayr, Mandy Rettel, Mikhail M. Savitski, Dmitri I. Svergun, Wilbert Bitter, Matthias Wilmanns, Thomas C. Marlovits, Annabel H. A. Parret, Edith N. G. Houben. Structure of the mycobacterial ESX-5 type VII secretion system membrane complex by single-particle analysis. Nature Microbiology, 2017; 2: 17047 DOI: 10.1038/nmicrobiol.2017.47

Posted by Dr. Tim Sandle