FRANKFURT. Bacteria of
the species Thermus thermophilus possess
two types of extensions on their surface (pili) for the purpose of motion and for
capturing and absorbing DNA from their environment. This has been discovered by
researchers at Goethe University together with researchers in Great Britain.
The discovery of the motion pilus helps to better understand the functionality
of the DNA-capturing pilus functions. (Nature Communications, DOI 10.1038/s41467-020-15650-w)
The bacteria Thermus thermophilus likes it hot. It was first discovered in the
hot springs at Izu in Japan, where it thrives at an optimal temperature of
about 65 degrees Celsius. Like all bacteria, Thermus thermophilus has developed mechanisms to adjust to changing
environmental conditions. The bacteria changes its genetic material by
exchanging DNA with other bacteria, or absorbing DNA fragments from its
environment. These might come from dead bacteria cells, plants or animals. The
bacteria incorporate the DNA fragments into their genetic material and keep it if
the DNA proves useful.
Microbiologists at Goethe University led
by Professor Beate Averhoff from the Molecular Microbiology & Bioenergetics
of the Department of Molecular Biosciences together with a team of scientists
led by Dr Vicky Gold from the “Living Systems" Institute of the University of
Exeter in Great Britain have now studied the tiny hairs (called pili) on the
surface of the Thermus bacteria. The
scientists discovered that there are two types of pili with different
functions. High-resolution electron microscope images from Great Britain allow
thick and thin pili to be distinguished, and the Frankfurt scientists used
biochemical and molecular biological methods to demonstrate that the thick pili
are for DNA capture, and the thin pili for moving on surfaces.
“We want to find out exactly how Thermus thermophilus absorbs DNA from
its environment using its pili, as the precise mechanism is unknown," explains
Professor Beate Averhoff from the Institute for Molecular Biosciences at Goethe
University. “Through our most recent investigations we have learned that Thermus bacteria have distinct pili for
motion. Therefore, the thick pili possibly serve the purpose of DNA absorption,
which demonstrates how important this process is for the bacteria. In our
structure analyses we also found an area on the thick pili where DNA could bind."
The interplay of electron microscopy and
molecular biology also allowed the scientists to better understand the
mechanics of the pili. For both motion and DNA absorption, pili have to be
dynamic, i.e., able to be extended and retracted. “For the first time, the high
resolution structure of both pili gave us insights not only into the structure
of the pili, but also into the dynamics," Averhoff explains.
Since pili are widespread and in
pathogenic bacteria are also responsible for attaching to the host, this may
lead to new points of attack for preventing infectious processes.
Publication:
Alexander Neuhaus, Muniyandi Selvaraj, Ralf Salzer,
Julian D. Langer, Kerstin Kruse, Lennart Kirchner, Kelly Sanders, Bertram Daum,
Beate Averhoff, Vicki A. M. Gold (2020). Cryo-electron microscopy reveals two
distinct type-IV pili assembled by the same bacterium. Nature Communications, https://doi.org/10.1038/s41467-020-15650-w )
An
image may be downloaded here: http://www.uni-frankfurt.de/88063448
Caption:
Bacteria of the species Thermus thermophilus possess different tiny hairs (pili) which are
used either to capture DNA or for motion. This has been discovered by
scientists at Goethe University Frankfurt and the University of Exeter. Graphic:
aduka, Agency Frankfurt am Main(www.aduka.de) for Goethe University Frankfurt.
Further
information: Prof. Beate Averhoff, Molecular Microbiology and Bioenergetics. Tel.:
+49 69 798-29509, averhoff@bio.uni-frankfurt.de, https://www.mikrobiologie-frankfurt.de
