Goethe University. Germany: Bacteria communicate by means of chemical signals and can develop common
characteristics through this "agreement" and also develop their
potential pathogenic effects in this way. Scientists working with Dr.
Helge B. Bode, an Merck-endowed professor for molecular biotechnology at
the Goethe University in Frankfurt, and Dr. Ralf Heermann from the
department of microbiology at the Ludwig Maximilian University in
Munich, have now described a hitherto unknown communication pathway that
appears to be widely distributed. They report on this in the journal
Proceedings of the National Academy of Science.
The investigation
of bacterial communication is also of medical interest. This is because
the bacterial communication pathways are a possible therapeutic target
for new medicines. If the relevant communication options are prevented,
the bacteria cannot develop their pathogenic properties. "When pathogens
are no longer destroyed by antibiotics as we have seen to date, but
rather be impaired beforehand the formation of the pathogenic
properties, the danger of resistance development would be substantially
reduced", says Bode.
Different types of bacteria also have
different methods of communication. The team lead by Heerman and Bode
had already discovered a new bacterial communication pathway in 2013.
Now they have succeeded in decoding a further new and widely distributed
chemical type of bacterial communication.
To date, the best
known communication between bacteria occurs via the N-acyl homoserine
lactone (AHL): The enzyme Luxl produces signals that are recognised by
the LuxR receptor, at which point the bacteria develop certain
properties and modulate their behaviour towards one another. Since a
certain number of bacteria must be available for this to occur, this
process is known as "quorum sensing".
However, Heermann's and
Bode's working groups investigate bacteria that possess a LuxR receptor,
but not the enzyme Luxl. In the current study, the microbiologists have
investigated the bacteria Photorhabdus asymbiotica, which is a deadly
pathogen in insects, which also infects humans and can cause skin
infections. These bacteria communicate via the signal molecule
dialkylresorcinol, which recognised the associated LuxR receptor. "The
influence on the pathogenic properties of the bacteria is at its
strongest in this 'quorum sensing' system. P. asymbiotica requires
dialkylresorcinol and in this way coordinates the communication with the
conspecifics for the successful infection of the larvae", says Helge
Bode, whose group in 2013 also described the biosynthesis of this new
signal molecule.
The researchers have not only investigated P.
asymbiotica, but also a series of other bacterial genomes. The newly
discovered signal pathway appears to be widely distributed. "We were
able to identify several other bacteria that are pathogenic to humans
that also do not express Luxl and also possess this ability for forming
these signals", says Heerman.
Publication:
Sophie Brameyer, Darko Kresovic, Helge B. Bode and Ralf Heermann:
Dialkylresorcinols as bacterial signaling molecules
In: PNAS 112 (2), 572-577.
DOI: 10.1073/pnas.1417685112
www.pnas.org/cgi/doi/10.1073/pnas.1417685112