In order to interact with the environment, bacteria secrete a whole arsenal of proteins. Researchers have now found how one of the transportation systems used for this purpose – the type VI secretion system – works for the single-celled organism Agrobacterium tumefaciens. They have identified the relevant transport proteins and their energy suppliers.
Export mechanism: To get to the outside, Hcp has to get past two cell membranes. This is only possible if it forms a complex with the two membrane proteins TssM (grey) and TssL (white). The energy for the export is produced by the interaction of TssM with the energy storage molecule ATP. Figure: modified from the Journal of Biological Chemistry
With colleagues at the Academia Sinica in Taiwan, RUB biologist Prof. Dr. Franz Narberhaus describes the findings in the Journal of Biological Chemistry. “The proteins involved also occur in other secretion apparatuses” explains Narberhaus from the Department of Microbial Biology. “Therefore, the results contribute to the general understanding of the system.”
Protein arsenal for many purposes
Bacteria use secreted proteins to make nutrients available, to fend off competitors and to infect human, animal or plant host cells. “Agrobacterium tumefaciens is a fascinating bacterium. It can genetically modify plants and stimulate tumour formation”, says Narberhaus. Five bacterial secretion systems have been known for a long time. The type VI system was only discovered a few years ago. Among other things, it transports the protein Hcp through two membranes into the environment – for what purpose is, as yet, unclear. The question of how the export of Hcp is driven was also unanswered. This is precisely what the German-Taiwanese team has now revealed.
Membrane protein TssM: the driver of the protein export
Narberhaus and his colleagues have shown that two proteins in the cell membrane of the bacteria, called TssL and TssM, are responsible for the export of Hcp. The molecule ATP, a cellular energy store, serves as fuel for the transport process. The membrane protein TssM binds the energy supplier ATP, thereby changing its own structure and splitting the ATP. The energy thus released allows the associated membrane protein TssL to bind its cargo (Hcp) so that a tripartite complex of TssM, TssL and Hcp is formed. Hcp only passes from the bacterial cell into the environment when this complex forms.
Successful cooperation between Bochum und Taiwan
“Large membrane proteins such as TssM are difficult to study biochemically. Our colleagues in Taiwan have done a great job” Prof. Narberhaus explains. “It will now be particularly interesting to explore the biological significance of the system.” The analyses of ATP splitting, also called hydrolysis, were established in Prof. Narberhaus’s laboratory by the doctoral student Lay-Sun Ma during a research visit. “Because of the participation in the Collaborative Research Centre SFB 642 ‘GTP- and ATP-dependent membrane processes’, we are able to offer ideal conditions for working with ATP-dependent proteins” the RUB-biologist explains. This is the second time that the DAAD has funded the cooperation between the laboratories of Franz Narberhaus and Erh-Min Lai. The successful cooperation is also to continue in the future. “It is bound to last for many years”, the Bochum researcher is convinced. The next exchange of doctoral students is planned for autumn.
L.-S. Ma, F. Narberhaus, E.-M. Lai (2012): IcmF family protein TssM exhibits ATPase activity and energizes type VI secretion, Journal of Biological Chemistry, doi: 10.1074/jbc.M111.301630
Further informationProf. Dr. Franz Narberhaus, Department of Microbial Biology, Faculty of Biology and Biotechnology at the Ruhr-Universität, 44780 Bochum, Germany, Tel. +49/234/32-23100
Click for moreMicrobial biology at the RUB
Dr. Josef König | idw
Scientists uncover the role of a protein in production & survival of myelin-forming cells
19.07.2018 | Advanced Science Research Center, GC/CUNY
NYSCF researchers develop novel bioengineering technique for personalized bone grafts
18.07.2018 | New York Stem Cell Foundation
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
20.07.2018 | Power and Electrical Engineering
20.07.2018 | Information Technology
20.07.2018 | Materials Sciences