Bacterial protein impairs important cellular processes

Pseudomonas aeruginosa lectin LecB can block the cell cycle. Credit: AG Römer

LecB of Pseudomonas aeruginosa is a bacterial virulence factor that impairs signaling of growth factor receptors- in other words, proteins found on the surface of host cells that transmit signals to promote the growth and reproduction of tissues. As a result, the cell cycle is blocked.

Lectins are proteins that bind to sugar residues on surface receptors and are not catalytically active, meaning they do not accelerate chemical processes. Many bacteria use lectins to bind effectively to the epithelium and endothelium layers of cells coating the body's surface area, thus facilitating the colonization of tissue.

The researchers discovered that the bacterial lectin LecB is present in chronically infected human wounds, therefore making it possible for Pseudomonas aeruginosa to remain in those wounds. They also determined that LecB is capable of inducing the internalization – in other words, the uptake into the cell's interior – and the degradation of growth factor receptors in keratinocytes, a type of cell in the epidermis.

Normally, the binding of growth factors to growth factor receptors activates so-called downstream signaling pathways, which accelerate tissue growth. “We were surprised that LecB does not contribute to the activation of growth factor signaling pathways, but that it triggers this silent internalization of receptors without activation,” says Alessia Landi, one of the researchers from the University of Freiburg and the paper's first author.

The scientists also demonstrated that LecB blocks the cell cycle and causes cell death. This process is preceded by intense vacuolization, which is the development of several larger, enclosed sacs (vacuoles) within the host cell. These vacuoles, which display unique morphological characteristics, are formed by structures of plasma membranes in which LecB is enriched.

“Although lectins are not catalytically active, LecB appears to interfere with important host cell processes, like the cell cycle, in a way we don't yet understand,” says Römer, adding: “This likely occurs through a restructuring of the cell membrane triggered by LecB.”

The discovery of this new function of the Pseudomonas aeruginosa lectin LecB has motivated the team to pursue more research. As Römer says, it is possible that LecB also has this function of promoting the further damage of tissue and facilitating the spread of bacteria in other cell types as well, including immune cells. Future studies will therefore focus on the effects of LecB on immune responses in chronic wound infections.

###

The team of researchers consists of members from the University of Freiburg's excellence clusters in biological signaling studies BIOSS and CIBSS, the Spemann Graduate School of Biology and Medicine, the University Medical Center Freiburg, the Università della Svizzera italiana in Lugano, Italy, and the University Medical Center Groningen, Netherlands.

Original Publication:

Landi, A., Mari, M. C., Kleiser, S., Wolf, T., Gretzmeier, C., Wilhelm, I., Kiritsi, D., Thünauer, R., Geiger, R., Nyström, A., Reggiori, F., Claudinon, J., Römer, W. (2019): P. aeruginosa lectin LecB impairs keratinocyte fitness by abrogating growth factor signalling. Life Science Alliance. DOI: 10.26508/lsa.201900422

Contact:

Excellence Clusters in Biological Signaling Studies BIOSS and CIBSS
University of Freiburg

Media Contact

Prof. Dr. Winfried Römer
winfried.roemer@bioss.uni-freiburg.de
49-761-203-67500

http://www.uni-freiburg.de/ 

Media Contact

Prof. Dr. Winfried Römer EurekAlert!

All latest news from the category: Life Sciences and Chemistry

Articles and reports from the Life Sciences and chemistry area deal with applied and basic research into modern biology, chemistry and human medicine.

Valuable information can be found on a range of life sciences fields including bacteriology, biochemistry, bionics, bioinformatics, biophysics, biotechnology, genetics, geobotany, human biology, marine biology, microbiology, molecular biology, cellular biology, zoology, bioinorganic chemistry, microchemistry and environmental chemistry.

Back to home

Comments (0)

Write a comment

Newest articles

Lighting up the future

New multidisciplinary research from the University of St Andrews could lead to more efficient televisions, computer screens and lighting. Researchers at the Organic Semiconductor Centre in the School of Physics and…

Researchers crack sugarcane’s complex genetic code

Sweet success: Scientists created a highly accurate reference genome for one of the most important modern crops and found a rare example of how genes confer disease resistance in plants….

Evolution of the most powerful ocean current on Earth

The Antarctic Circumpolar Current plays an important part in global overturning circulation, the exchange of heat and CO2 between the ocean and atmosphere, and the stability of Antarctica’s ice sheets….

Partners & Sponsors