Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

UMD-led study identifies the off switch for biofilm formation

25.08.2015

New discovery could help prevent the formation of infectious bacterial films on hospital equipment

Bacteria are best known as free-living single cells, but in reality their lives are much more complex. To survive in harsh environments, many species of bacteria will band together and form a biofilm--a collection of cells held together by a tough web of fibers that offers protection from all manner of threats, including antibiotics. A familiar biofilm is the dental plaque that forms on teeth between brushings, but biofilms can form almost anywhere given the right conditions.


In this false-colored image, individual cells of Pseudomonas aeruginosa (green) can be seen resting on the fibrous surface of a biofilm (purple) that helps protect cells beneath its surface. At top right, two cells incorporated within the biofilm peek out from a fissure in the film's surface.

Credit: Debra Weinstein, Sao-Mai Nguyen-Mau, and Vincent Lee

Biofilms are a huge problem in the health care industry. When disease-causing bacteria establish a biofilm on sensitive equipment, it can be impossible to sterilize the devices, raising rates of infection and necessitating expensive replacements. So researchers look for ways to break down the defenses of biofilms to prevent them from establishing a foothold.

Now, a University of Maryland-led team has found an important link in the biofilm formation process: an enzyme that shuts down the signals that bacteria use to form a biofilm. The findings, reported in the August 24, 2015 Early Online Edition of the Proceedings of the National Academy of Sciences, have far-reaching implications for the development of new treatments, and could one day help make biofilm-related complications a distant memory.

"Bacteria form biofilms because they sense a change in their environment. They do this by generating a signaling molecule, which binds to a receptor that turns on the response," said Mona Orr, the lead author of the study and a UMD biological sciences graduate student. "But you need a way to turn off the switch--to remove the signal when it's no longer needed. We've identified the enzyme that completes the process of turning off the switch."

The well-known switch that activates biofilm formation is a signaling molecule called Cyclic-di-GMP, also known as c-di-GMP. Many species of disease-causing bacteria use c-di-GMP to signal the formation of biofilms, including Escherichia coli, Salmonella enterica and Vibrio cholerae.

But Orr and her colleagues are the first to identify the molecule that completes the process of clearing c-di-GMP from the cell, thus ending the biofilm signaling process. The molecule is an enzyme called oligoribonuclease, and much like c-di-GMP, oligoribonuclease is also common among disease-causing bacterial species.

The team studied the process in the bacteria Pseudomonas aeruginosa, a common species known to cause infections in hospital patients. But because of the genetic and physiological similarities between P. aeruginosa and other infectious species, the researchers believe that oligoribonuclease serves the same function across a wide variety of bacteria.

"You can think of this process in terms of water filling a sink. The rate of water from the faucet is just as important as the size of the drain in determining the level of water in the sink," said Vincent Lee, a co-author of the study and an associate professor in the UMD Department of Cell Biology and Molecular Genetics and the Maryland Pathogen Research Institute. "The level of c-di-GMP in the cell is analogous to the amount of water in the sink. Because no one knew what the drain was, our findings create a complete picture of the signaling process."

Orr, Lee and their colleagues from the UMD Department of Chemistry and Biochemistry and Michigan State University focused their work on P. aeruginosa because it is well studied and can survive under a variety of conditions, making it notoriously difficult to control. Contact lens wearers might already be familiar with P. aeruginosa, as it commonly forms infectious, green-tinted biofilms on older lenses or those that have not been cleaned properly.

The team found that oligoribonuclease is necessary for the second of a two-step process. The first, which converts c-di-GMP into an intermediate molecule called pGpG, was already known. Orr, Lee and their colleagues have now filled in the important second step in this process: oligoribonuclease breaks apart pGpG and thus completely shuts off the signaling pathway.

The result suggests that oligoribonuclease could be used to help design new antibiotics, disinfectants, and surface treatments to control biofilms. Such measures could prevent infections and preclude the need for frequent replacement of expensive hospital equipment. Because biofilms can also form on implanted medical devices, such as pacemakers and synthetic joints, effective treatments against biofilms could eliminate the need for costly and risky replacement surgeries.

While oligoribonuclease most likely shuts down biofilm formation in many infectious bacterial species, Orr and Lee acknowledge that their discovery is not quite a "silver bullet" that can fight every type of biofilm.

"The genes that make these signals are found in most bacteria. The oligoribonuclease enzyme that breaks the effect is only found in some, however," Lee explained. "So there must be parallels in the organisms that don't have oligoribonuclease. Finding these other 'off' switches is high on our list of future research goals."

###

In addition to Orr and Lee, UMD authors on the paper include Herman Sintim, associate professor in the UMD Department of Chemistry and Biochemistry, Jingxin Wang (Ph.D. '11, chemistry) and Gregory Donaldson (B.S. '10, biological sciences).

This work was funded by the National Institutes of Health's National Institute of Allergy and Infectious Diseases (Award Nos. T32-AI089621 and R21AI096083) and the National Science Foundation (Award Nos. MCB1253684 and CHE0746446). The content of this article does not necessarily reflect the views of these organizations.

The research paper, "Oligoribonuclease is the primary degradative enzyme for pGpG in Pseudomonas aeruginosa that is required for cyclic-di-GMP turnover," Mona Orr, Gregory Donaldson, Geoffrey Severin, Jingxin Wang, Herman Sintim, Christopher Waters, and Vincent Lee, was published August 24, 2015 in the Early Online Edition of the Proceedings of the National Academy of Sciences.

Media Relations Contact: Matthew Wright, 301-405-9267, mewright@umd.edu

University of Maryland
College of Computer, Mathematical, and Natural Sciences
2300 Symons Hall
College Park, MD 20742
http://www.cmns.umd.edu
@UMDscience

About the College of Computer, Mathematical, and Natural Sciences

The College of Computer, Mathematical, and Natural Sciences at the University of Maryland educates more than 7,000 future scientific leaders in its undergraduate and graduate programs each year. The college's 10 departments and more than a dozen interdisciplinary research centers foster scientific discovery with annual sponsored research funding exceeding $150 million.

Media Contact

Matthew Wright
mewright@umd.edu
301-405-9267

 @UMDRightNow

http://www.newsdesk.umd.edu/ 

Matthew Wright | EurekAlert!

More articles from Life Sciences:

nachricht Immune Defense Without Collateral Damage
23.01.2017 | Universität Basel

nachricht The interactome of infected neural cells reveals new therapeutic targets for Zika
23.01.2017 | D'Or Institute for Research and Education

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Quantum optical sensor for the first time tested in space – with a laser system from Berlin

For the first time ever, a cloud of ultra-cold atoms has been successfully created in space on board of a sounding rocket. The MAIUS mission demonstrates that quantum optical sensors can be operated even in harsh environments like space – a prerequi-site for finding answers to the most challenging questions of fundamental physics and an important innovation driver for everyday applications.

According to Albert Einstein's Equivalence Principle, all bodies are accelerated at the same rate by the Earth's gravity, regardless of their properties. This...

Im Focus: Traffic jam in empty space

New success for Konstanz physicists in studying the quantum vacuum

An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...

Im Focus: How gut bacteria can make us ill

HZI researchers decipher infection mechanisms of Yersinia and immune responses of the host

Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Sustainable Water use in Agriculture in Eastern Europe and Central Asia

19.01.2017 | Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

 
Latest News

Tracking movement of immune cells identifies key first steps in inflammatory arthritis

23.01.2017 | Health and Medicine

Electrocatalysis can advance green transition

23.01.2017 | Physics and Astronomy

New technology for mass-production of complex molded composite components

23.01.2017 | Process Engineering

VideoLinks
B2B-VideoLinks
More VideoLinks >>>