The pneumonia causing pathogen Pseudomonas aeruginosa has developed a twin-track strategy to colonize its host. It generates two different cells – motile spreaders and virulent stickers. Researchers at the University of Basel’s Biozentrum have now elucidated how the germ attaches to tissue within seconds and consecutively spreads. Just like the business model: settling – growing – expanding. The study has been published in Cell Host & Microbe.
The bacterium Pseudomonas aeruginosa is one of the most common and dangerous pathogens in hospitals causing severe infections in patients, such as wound infections, pneumonia or meningitis.
During the first stage of infection, the pathogen needs to effectively attach to host tissue but at the same time spread to distant sites.
At later stages of infection, the pathogen needs to re-adjust its behavior to permanently colonize the host and hide from its immune system, for example, by forming protective biofilms.
From spreading to adhering cells
The key to success for P. aeruginosa is its perfected colonization strategy. “During each division, the pathogen generates two distinct cell types, an attacking sticker and a motile spreader,” explains Prof. Urs Jenal, research group leader at the Biozentrum of the University of Basel.
“The balance between these two cell types is crucial for the pathogen in order to successfully dwell on tissues and to disseminate rapidly.”
In the initial phase of an infection, the spreader actively moves towards tissue surfaces of the host with a rotating cell propeller, called flagellum. The researchers have now discovered that the flagellum also serves as a mechanical sensor.
“When the flagellum encounters a surface, bacteria rapidly respond by producing adhesive protrusions that firmly anchor the bacterium to the tissue,” says Jenal.
“We were most surprised by how quickly this happens. Within seconds, the bacteria change their program to stick to the surface.” The tactile stimulus triggers the production of the bacterial signaling molecule cyclic-di-GMP, which in turn initiates the formation of the cell protrusions.
From adhering to spreading cells
Furthermore, the researchers have been able to show that upon division, surface attached bacteria generate two different offspring: one daughter cell remains a sticker that can damage the underlying host tissue, the other one becomes a spreader disseminating to distant sites. This process is also known as asymmetric cell division.
“This is due to the asymmetrical distribution of cyclic-di-GMP in the dividing mother cell,” explains first author Benoît Laventie. While the daughter cell with high cyclic-di-GMP level remains attached to the landing site, the cell with low cyclic-di-GMP concentrations leaves the surface to colonize distant sites. Thus, P. aeruginosa exploits a simple business model: first establish, then grow and finally expand.
A smart tactic: conquer and hide
However, there is a limited window of opportunity for P. aeruginosa. After a few asymmetric divisions, the bacteria revert to dividing symmetrically producing exclusively virulent surface-attached offspring, thereby increasing the population at local sites exponentially.
The pathogen has changed its strategy and is aiming for long-term establishment in the host and escaping the host's defense systems.
The researchers in the Jenal lab speculate that this colonization strategy is of a general nature and can be found in a wide variety of bacteria that effectively colonize different surfaces such as stones, shower curtains, coffee cups or human organs.
Prof. Dr. Urs Jenal, University of Basel, Biozentrum, Tel. +41 61 207 21 35, email: firstname.lastname@example.org
Dr. Katrin Bühler, University of Basel, Biozentrum, Communications, Tel. +41 61 207 09 74, email: email@example.com
Benoît-Joseph Laventie, Matteo Sangermani, Fabienne Estermann, Pablo Manfredi, Rémi Planes, Isabelle Hug, Tina Jaeger, Etienne Meunier, Petr Broz, Urs Jenal
A Surface-Induced Asymmetric Program Promotes Tissue Colonization by Pseudomonas aeruginosa
Cell Host & Microbe (2018), doi: 10.1016/j.chom.2018.11.008
Dr. Katrin Bühler | Universität Basel
How molecules teeter in a laser field
18.01.2019 | Forschungsverbund Berlin
Discovery of enhanced bone growth could lead to new treatments for osteoporosis
18.01.2019 | University of California - Los Angeles
The scientific and political community alike stress the importance of German Antarctic research
Joint Press Release from the BMBF and AWI
The Antarctic is a frigid continent south of the Antarctic Circle, where researchers are the only inhabitants. Despite the hostile conditions, here the Alfred...
World first experiments on sensor that may revolutionise everything from medical devices to unmanned vehicles
The new sensor - capable of detecting vibrations of living cells - may revolutionise everything from medical devices to unmanned vehicles.
Dead and alive at the same time? Researchers at the Max Planck Institute of Quantum Optics have implemented Erwin Schrödinger’s paradoxical gedanken experiment employing an entangled atom-light state.
In 1935 Erwin Schrödinger formulated a thought experiment designed to capture the paradoxical nature of quantum physics. The crucial element of this gedanken...
Cellulose obtained from wood has amazing material properties. Empa researchers are now equipping the biodegradable material with additional functionalities to produce implants for cartilage diseases using 3D printing.
It all starts with an ear. Empa researcher Michael Hausmann removes the object shaped like a human ear from the 3D printer and explains:
The phenomenon of so-called superlubricity is known, but so far the explanation at the atomic level has been missing: for example, how does extremely low friction occur in bearings? Researchers from the Fraunhofer Institutes IWM and IWS jointly deciphered a universal mechanism of superlubricity for certain diamond-like carbon layers in combination with organic lubricants. Based on this knowledge, it is now possible to formulate design rules for supra lubricating layer-lubricant combinations. The results are presented in an article in Nature Communications, volume 10.
One of the most important prerequisites for sustainable and environmentally friendly mobility is minimizing friction. Research and industry have been dedicated...
16.01.2019 | Event News
14.01.2019 | Event News
12.12.2018 | Event News
18.01.2019 | Materials Sciences
18.01.2019 | Life Sciences
18.01.2019 | Health and Medicine