Scientists diarrhea examine the body temperature of the person

Intestinal bacteria recognize their host at body temperature
Bacteria perceive the ambient temperature with special RNA structures. In the past, finding them in the cells was extremely tedious. But now there is a new procedure.

Scientists decode all RNA structures of a diarrhea pathogen
Researchers have decrypted all RNA structures of a diarrheal pathogen at once using modern high-throughput sequencing methods. They discovered a whole series of temperature-sensitive structures called RNA thermometers. "So far, we have only found individual RNA thermometers after a lengthy search and laboriously examined them one after the other", explained project leader Prof. Dr. med. Franz Narberhaus of the Ruhr-Universität Bochum in a communication from the university. The Bochum scientists published their results together with colleagues from the Helmholtz Center for Infection Research in Braunschweig and the University of Leipzig in the journal "Proceedings of the National Academy of Sciences" ("PNAS").

Bacteria of the genus Yersinia cause in humans, among other inflammation of the intestinal wall and severe diarrheal diseases. Only above a certain temperature, the bacteria can spread in the host and trigger a disease. (Image: mmphoto / fotolia.com)

Bacteria can only spread from a certain temperature
"Bacteria of the genus Yersinia cause in humans, among other inflammation of the intestinal wall and severe diarrheal diseases. Even the causative agent of the plague belongs to this genus, "write the experts of the Helmholtz Center on their website. The scientists discovered various molecular switches in Yersinia pseudotuberculosis that change their three-dimensional structure at a temperature of 37 degrees Celsius. According to the researchers, the bacteria can then spread in the host and trigger a disease. The identified structures therefore offer targets for future drugs that block the temperature-dependent change and thus render the bacteria harmless.

Folded RNA as a thermometer
It has been known for years that certain intestinal bacteria, such as the Yersinia pseudotuberculosis examined here, recognize their warm-blooded host at body temperature. For this purpose, the bacteria use folded RNA structures, which melt at a certain temperature and thereby expose previously unavailable gene sequences. These can then be translated according to the scientists into proteins that control the disease process. In order to detect such cell thermometers, the research team used a combination of biochemical RNA structure mapping and high-throughput sequencing. They simultaneously decrypted the more than 1,750 RNA structures contained in the bacterial cell. The researchers reported that they performed the experiment at three different temperatures and each received a snapshot of RNA diversity.

Method is universally applicable
"For example, we were able to observe the dynamic changes in the RNA structures during a temperature increase from 25 to 37 degrees Celsius," explained the doctoral student responsible for this project at the Bochum Chair of Microorganisms, Francesco Righetti. "The technology we use is laborious," said the Braunschweig researcher. Aaron nut. "But it has huge potential for anyone interested in the biological function of RNA structures." It does not matter if you work with bacteria, plants, animals or human cells. The method is universally applicable.

Large number of temperature-dependent genes
"Our results show that a surprisingly large number of genes of the diarrheal pathogen Yersinia pseudotuberculosis reacts directly to the body temperature of the host," said Franz Narberhaus. For subsequent experiments, the experts selected 20 genes, 16 of which were actually temperature-dependent. These belong to different functional groups. For example, some are involved in the bacterium's response to oxidative stress. "It makes sense to initiate such processes directly after the infection of the host in order to prepare against the defense mechanisms in the human gastrointestinal tract", says Prof. Dr. med. Petra Dersch, infection biologist from Braunschweig. Current investigations are intended to show whether the newly identified RNA structures play a decisive role in the infection. In addition, the scientists want to clarify whether there are drugs that can prevent the melting of RNA thermometers. These could inhibit the infection process. (Ad)