Nav: Home

New compound allows bacterial communication to be controlled by light

April 15, 2019

Scientists from the University of Groningen have succeeded in incorporating a light-controlled switch into a molecule used by bacteria for quorum sensing - a process by which bacteria communicate and subsequently control different cellular processes. With the molecule described, it is possible to either inhibit or stimulate communication. This makes it a very useful tool for further research into bacterial communication and its influence on different genetic pathways. The results were published on 15 April in the journal Chem.

In order to respond to their environment, bacteria 'talk' to each other through a form of chemical communication called quorum sensing. The cells secrete a signal molecule and at the same time monitor its concentration. As more cells secrete the signal molecule, it can exceed a threshold concentration and activate certain genetic pathways, for example, to produce toxins or form a protective biofilm.

Light-sensitive switch

'If we would be able to influence quorum sensing, we might be able to use it to treat serious infections,' says University of Groningen organic chemist Mickel Hansen. 'And it would also be useful to investigate how quorum sensing exactly works.' To do this, it would be useful to have a modulator of quorum sensing that could be externally controlled. That is why Hansen and colleagues in the synthetic organic chemistry group led by Professor Ben Feringa set out to build a light-sensitive switch into a molecule used by bacteria as a signal for quorum sensing.

The molecule is made up of a head and a flexible carbon-based tail, connected via a β-keto-amide linker. The plan was to incorporate a switch into the tail. 'This meant we had to connect the modified tail to the head via β-keto-amide linkage. However, the synthetic process to obtain this linkage produces a very unstable intermediate, which made it almost impossible to synthesize the molecule.'

Library

Building on the extensive experience of the synthetic organic chemistry group at the Stratingh Institute of Chemistry at the University of Groningen, the researchers came up with a solution in the form of a new coupling reaction with a stabilized intermediate. Using this intermediate, they were able to synthesize photoswitchable derivatives in a fast and straightforward way.

Hansen, together with Master's student Jacques Hille, produced a 'library' of 16 different compounds that had the potential to act as agonists or antagonists of quorum sensing. All were fitted with a light-operated switch. All compounds were based on a molecule that is used in one particular quorum sensing system in Pseudomonas aeruginosa, which has about five of these quorum sensing systems. In collaboration with molecular biologists from the lab of Professor of Molecular Microbiology Arnold Driessen, also at the University of Groningen, the genes for one of these systems were transferred to an E. coli reporter strain, allowing any effect of the newly synthesized compounds to be tested without the interference of other quorum sensing mechanisms.

Toxin production

Bioactivity tests on the compounds obtained showed which parts of the molecule were crucial to controlling quorum sensing. The optimum number of carbon atoms making up the tail appeared to be four. Flipping the switch with light caused the tail to bend. Remarkably, the straight tail had no effect, whereas the bent tail induced the quorum sensing signal. Hansen: 'Overall, it appears that small changes in the molecule can have a large effect on its activity, but we don't yet know exactly why.'

They did find one compound that was able to strongly inhibit the quorum sensing signal and - after irradiation with light, leading to the bending of the tail - to also strongly stimulate it. The difference in activity was more than 700-fold, which is huge. 'Such a large difference has, to our knowledge, never been shown before for light-switched bioactive molecules.' This particular molecule will be a very useful tool for investigating how bacteria communicate. 'In the study, we showed that we could light-control toxin production in a Pseudomonas strain with our switchable modulator. This will be a powerful tool for both clinical and fundamental research into the mechanism of quorum sensing.'
-end-
The study was a cooperative effort of microbiologists from the Groningen Biomolecular Sciences and Biotechnology Institute (GBB) and organic chemists at the Stratingh Institute for Chemistry, both part of the Faculty of Science and Engineering at the University of Groningen.

Reference: Mickel J. Hansen, Jacques I.C. Hille, Wiktor Szymanski, Arnold J.M. Driessen, and Ben L. Feringa: Easily accessible, highly potent, photocontrolled modulators of bacterial communication. Chem, 15 April 2019.

University of Groningen

Related Bacteria Articles:

Bacteria must be 'stressed out' to divide
Bacterial cell division is controlled by both enzymatic activity and mechanical forces, which work together to control its timing and location, a new study from EPFL finds.
How bees live with bacteria
More than 90 percent of all bee species are not organized in colonies, but fight their way through life alone.
The bacteria building your baby
Australian researchers have laid to rest a longstanding controversy: is the womb sterile?
Detecting bacteria in space
A new genomic approach provides a glimpse into the diverse bacterial ecosystem on the International Space Station.
Hopping bacteria
Scientists have long known that key models of bacterial movement in real-world conditions are flawed.
Bacteria uses viral weapon against other bacteria
Bacterial cells use both a virus -- traditionally thought to be an enemy -- and a prehistoric viral protein to kill other bacteria that competes with it for food according to an international team of researchers who believe this has potential implications for future infectious disease treatment.
Drug diversity in bacteria
Bacteria produce a cocktail of various bioactive natural products in order to survive in hostile environments with competing (micro)organisms.
Bacteria walk (a bit) like we do
EPFL biophysicists have been able to directly study the way bacteria move on surfaces, revealing a molecular machinery reminiscent of motor reflexes.
Using bacteria to create a water filter that kills bacteria
Engineers have created a bacteria-filtering membrane using graphene oxide and bacterial nanocellulose.
Probiotics are not always 'good bacteria'
Researchers from the Cockrell School of Engineering were able to shed light on a part of the human body - the digestive system -- where many questions remain unanswered.
More Bacteria News and Bacteria Current Events

Top Science Podcasts

We have hand picked the top science podcasts of 2019.
Now Playing: TED Radio Hour

In & Out Of Love
We think of love as a mysterious, unknowable force. Something that happens to us. But what if we could control it? This hour, TED speakers on whether we can decide to fall in — and out of — love. Guests include writer Mandy Len Catron, biological anthropologist Helen Fisher, musician Dessa, One Love CEO Katie Hood, and psychologist Guy Winch.
Now Playing: Science for the People

#543 Give a Nerd a Gift
Yup, you guessed it... it's Science for the People's annual holiday episode that helps you figure out what sciency books and gifts to get that special nerd on your list. Or maybe you're looking to build up your reading list for the holiday break and a geeky Christmas sweater to wear to an upcoming party. Returning are pop-science power-readers John Dupuis and Joanne Manaster to dish on the best science books they read this past year. And Rachelle Saunders and Bethany Brookshire squee in delight over some truly delightful science-themed non-book objects for those whose bookshelves are already full. Since...
Now Playing: Radiolab

An Announcement from Radiolab