Researchers have been unclear on how bacteria form and release certain extracellular components involved in cell adhesion and multicellular structures that also contribute to antibiotic resistance. However, a recent study from a multinational team of researchers identified a previously unknown phenomenon, explosive cell lysis, as crucial in the production of membrane vesicles and biofilm formation. The study was reported in Nature Communications.
Membrane vesicles are tiny spheres that develop from bacterial membranes and contain a mixture of proteins, DNA, and RNA. They are important for the virulence of the bacterium--its ability to cause disease--as they play vital roles in invasion, secretion, and signaling.
They also contribute to the formation of biofilms, the slimy three-dimensional structures that form when bacteria adhere to moist surfaces such as teeth or wounds. Extracellular (e)DNA is a key structural organization of biofilms, yet it was not known how certain structural proteins or eDNA are released.
To answer this, the researchers used live cell microscopy of the pathogenic bacterium Pseudomonas aeruginosa to reveal that cells quickly changed from rod- to round-shaped, and explode. "Cells lose their structural integrity in 5-10 seconds," corresponding author Cynthia Whitchurch of the University of Technology Sydney explains, "and the explosion releases cellular content including eDNA, proteins, and membrane fragments into the surrounding environment."
Using super-resolution microscopy to follow the explosions, they found a surprising observation described by first author Lynne Turnbull: "We observed that membrane fragments produced by exploding bacteria curled up to form membrane vesicles that captured eDNA and other cellular components released by the explosion."
Co-corresponding and co-first author Masanori Toyofuku of the University of Tsukuba and University of Zurich explains that, "this was completely unexpected as until now bacterial membrane vesicles were thought to form from membranous protrusions at the cell surface."
The team found that the explosions are caused by an enzyme (Lys) used by bacteria-infecting viruses (phages) and phage-like elements to disrupt the cell wall of their hosts. Using a mutant bacterial strain incapable of producing Lys, they discovered that the enzyme was needed to produce eDNA and membrane vesicles.
Through a range of experiments, the team also demonstrated that exposure of cells to different forms of stress, such as antibiotics or DNA damaging agents, stimulated expression of the gene encoding Lys and induced explosive cell lysis. "This shows that the bacterial 'SOS' response triggers explosive cell lysis in response to unfavorable environmental conditions," co-corresponding author Leo Eberl of the University of Zurich says.
This mechanism may enable bacteria to release important cellular factors for use by bacterial communities as public goods, and knowledge of its control could be used to interfere with biofilm formation of pathogenic bacteria.
Masataka Watanabe | EurekAlert!
Symbiotic bacteria: from hitchhiker to beetle bodyguard
28.04.2017 | Johannes Gutenberg-Universität Mainz
Nose2Brain – Better Therapy for Multiple Sclerosis
28.04.2017 | Fraunhofer-Institut für Grenzflächen- und Bioverfahrenstechnik IGB
More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.
Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...
Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.
"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...
The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.
Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...
The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...
Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.
Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...
28.04.2017 | Event News
20.04.2017 | Event News
18.04.2017 | Event News
28.04.2017 | Medical Engineering
28.04.2017 | Earth Sciences
28.04.2017 | Life Sciences