Nav: Home

How diarrhea pathogens switch into attack mode at body temperature

January 20, 2020

Many bacterial pathogens excrete toxins as soon as they have entered the host in order to suppress its immune response. Researchers at Ruhr-Universität Bochum (RUB) have analysed what happens on the molecular level when the diarrhea pathogen Yersinia pseudotuberculosis switches into attack mode. To this end, they examined so-called RNA thermometers, which signal to the bacteria whether they are in the host.

In collaboration with colleagues from the Helmholtz Institute for Infection Research in Braunschweig, they also showed that bacteria with deactivated RNA thermometers can no longer trigger an infection. The journal PLOS Pathogens reports about the study online on 17. january 2020.

RNA thermometer melts at 37 degrees Celcius

"We knew from previous studies that Yersinia bacteria are very sensitive to temperature changes and recognise that they are in their host on the basis of body temperature," says Professor Franz Narberhaus from the RUB Chair of Microbial Biology. RNA thermometers are responsible for temperature measurement. They are sections in the messenger RNA of many genes that contain the blueprint for disease-causing proteins.

At low temperatures, i.e. outside the host, RNA thermometers prevent the RNA from being read and translated into proteins. Only after successful infection of the warm-blooded host, i.e. at a temperature of around 37 degrees Celsius, do the RNA structures melt. They can then be written into proteins that have a harmful effect on the host. In the current publication, the scientists describe the underlying melting mechanism of the RNA thermometer for one of the toxins of Yersinia pseudotuberculosis, namely the CnfY-Toxin.

Bacteria with non-functional thermometers do not cause illness

PhD student Christian Twittenhoff from Bochum used isolated cell components of the diarrhoea pathogen to show which structure the RNA thermometer for the CnfY toxin assumes and where it melts. The biologist created a model that documents how the thermometer opens. It also shows how the ribosome - the cell component on which the messenger RNA is translated into a protein - docks to the messenger RNA.

In cooperation with the group headed by Professor Petra Dersch, formerly at Helmholtz Institute in Braunschweig, currently at the University of Münster, the researchers moreover demonstrated the role of the RNA thermometer in the disease process. They infected mice with Yersinia bacteria that either had functioning RNA thermometers or inactivated RNA thermometers that could not melt at 37 degrees Celsius. The bacterial strains with modified RNA thermometers were not able to make mice ill. "The results have shown how important very short regulatory RNA sequences can be for the successful course of infection of a bacterium," concludes Christian Twittenhoff, lead author of the study.

Similar mechanisms suspected in other bacteria

Christian Twittenhoff compared the gene of the CnfY toxin with toxin genes of other pathogens using bioinformatic methods. The analysis suggests that other toxin genes might also be regulated by RNA thermometers. "Even though the sequences are very different, we are able to predict which RNA structures are likely to act as thermometers," he explains.

"RNA thermometers function via a very simple mechanism, which has probably proved its efficacy in the course of evolution and has therefore developed many times and independently of each other," assumes Franz Narberhaus. In principle, it is possible to prevent bacterial infection by preventing the melting of such RNA structures. "However, we don't yet know any substances that freeze RNA thermometers in the closed state," continues Narberhaus.
-end-
About the pathogen

The diarrhoea pathogen Yersinia pseudotuberculosis is closely related to the plague pathogen Yersinia pestis. The bacterium is transmitted via contaminated food. As soon as it arrives in the intestine of the warm-blooded host, it secretes the so-called CnfY toxin, which triggers acute inflammatory reactions and increases the effect of other pathogenic substances.

Funding

The German Research Foundation funded the project under the funding code NA 240/10-2.

Original publication

Christian Twittenhoff, Ann Kathrin Heroven, Sabrina Mühlen, Petra Dersch, Franz Narberhaus: An RNA thermometer dictates production of a secreted bacterial toxin, in: PLOS Pathogens, 2019, DOI: 10.1371/journal.ppat.1008184

Press contact

Prof. Dr. Franz Narberhaus
Chair of Microbial Biology
Faculty of Biology and Biotechnology
Ruhr-Universität Bochum
Germany
Phone: +49 234 32 23100
Email: franz.narberhaus@rub.de

Ruhr-University Bochum

Related Science Articles:

75 science societies urge the education department to base Title IX sexual harassment regulations on evidence and science
The American Educational Research Association (AERA) and the American Association for the Advancement of Science (AAAS) today led 75 scientific societies in submitting comments on the US Department of Education's proposed changes to Title IX regulations.
Science/Science Careers' survey ranks top biotech, biopharma, and pharma employers
The Science and Science Careers' 2018 annual Top Employers Survey polled employees in the biotechnology, biopharmaceutical, pharmaceutical, and related industries to determine the 20 best employers in these industries as well as their driving characteristics.
Science in the palm of your hand: How citizen science transforms passive learners
Citizen science projects can engage even children who previously were not interested in science.
Applied science may yield more translational research publications than basic science
While translational research can happen at any stage of the research process, a recent investigation of behavioral and social science research awards granted by the NIH between 2008 and 2014 revealed that applied science yielded a higher volume of translational research publications than basic science, according to a study published May 9, 2018 in the open-access journal PLOS ONE by Xueying Han from the Science and Technology Policy Institute, USA, and colleagues.
Prominent academics, including Salk's Thomas Albright, call for more science in forensic science
Six scientists who recently served on the National Commission on Forensic Science are calling on the scientific community at large to advocate for increased research and financial support of forensic science as well as the introduction of empirical testing requirements to ensure the validity of outcomes.
World Science Forum 2017 Jordan issues Science for Peace Declaration
On behalf of the coordinating organizations responsible for delivering the World Science Forum Jordan, the concluding Science for Peace Declaration issued at the Dead Sea represents a global call for action to science and society to build a future that promises greater equality, security and opportunity for all, and in which science plays an increasingly prominent role as an enabler of fair and sustainable development.
PETA science group promotes animal-free science at society of toxicology conference
The PETA International Science Consortium Ltd. is presenting two posters on animal-free methods for testing inhalation toxicity at the 56th annual Society of Toxicology (SOT) meeting March 12 to 16, 2017, in Baltimore, Maryland.
Citizen Science in the Digital Age: Rhetoric, Science and Public Engagement
James Wynn's timely investigation highlights scientific studies grounded in publicly gathered data and probes the rhetoric these studies employ.
Science/Science Careers' survey ranks top biotech, pharma, and biopharma employers
The Science and Science Careers' 2016 annual Top Employers Survey polled employees in the biotechnology, biopharmaceutical, pharmaceutical, and related industries to determine the 20 best employers in these industries as well as their driving characteristics.
Three natural science professors win TJ Park Science Fellowship
Professor Jung-Min Kee (Department of Chemistry, UNIST), Professor Kyudong Choi (Department of Mathematical Sciences, UNIST), and Professor Kwanpyo Kim (Department of Physics, UNIST) are the recipients of the Cheong-Am (TJ Park) Science Fellowship of the year 2016.
More Science News and Science Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Listen Again: The Power Of Spaces
How do spaces shape the human experience? In what ways do our rooms, homes, and buildings give us meaning and purpose? This hour, TED speakers explore the power of the spaces we make and inhabit. Guests include architect Michael Murphy, musician David Byrne, artist Es Devlin, and architect Siamak Hariri.
Now Playing: Science for the People

#576 Science Communication in Creative Places
When you think of science communication, you might think of TED talks or museum talks or video talks, or... people giving lectures. It's a lot of people talking. But there's more to sci comm than that. This week host Bethany Brookshire talks to three people who have looked at science communication in places you might not expect it. We'll speak with Mauna Dasari, a graduate student at Notre Dame, about making mammals into a March Madness match. We'll talk with Sarah Garner, director of the Pathologists Assistant Program at Tulane University School of Medicine, who takes pathology instruction out of...
Now Playing: Radiolab

What If?
There's plenty of speculation about what Donald Trump might do in the wake of the election. Would he dispute the results if he loses? Would he simply refuse to leave office, or even try to use the military to maintain control? Last summer, Rosa Brooks got together a team of experts and political operatives from both sides of the aisle to ask a slightly different question. Rather than arguing about whether he'd do those things, they dug into what exactly would happen if he did. Part war game part choose your own adventure, Rosa's Transition Integrity Project doesn't give us any predictions, and it isn't a referendum on Trump. Instead, it's a deeply illuminating stress test on our laws, our institutions, and on the commitment to democracy written into the constitution. This episode was reported by Bethel Habte, with help from Tracie Hunte, and produced by Bethel Habte. Jeremy Bloom provided original music. Support Radiolab by becoming a member today at Radiolab.org/donate.     You can read The Transition Integrity Project's report here.