Researchers at the University of Basel’s Biozentrum have discovered that Bartonella bacteria exchange genes efficiently using a domesticated virus encoded in their genome. As the findings published in «Cell Systems» demonstrate, the exchange of genetic material only takes place between bacteria with a high level of fitness. The gene transfer between pathogens prevents the accumulation of genetic defects, promotes the spread of beneficial gene mutations and thus keeps the bacteria fit.
Bartonella are bacteria that can cause diverse infectious diseases in man, such as cat-scratch disease. In order to prevent the accumulation of mutations during the infection cycle, pathogens require efficient DNA repair mechanisms. Therefore, the sharing of intact genes within bacterial populations plays an important role, as errors in the gene pool can be eliminated and the genetic material kept fresh.
In collaboration with the ETH Zurich Prof. Christoph Dehio’s team at the Biozentrum, University of Basel, has discovered that for the efficient exchange of genes Bartonella use virus-like particles, so-called gene transfer agents. They also demonstrated that damaged bacteria are excluded from this gene transfer process and so it is much less likely that detrimental genetic material is spread in the population.
Gene transfer using domesticated viruses
Gene transfer agents evolved as derivatives of bacteriophages, viruses that attack bacteria. However, other than bacteriophages packing their own genome they package random pieces of the bacterial genome and transfer these to other bacteria. Using these domesticated bacteriophages, bacterial populations can efficiently exchange DNA fragments. This type of gene transfer, however, comes at a high price: The fraction of the bacterial population that produces gene transfer agents dies while releasing the particles. But what are the advantages for the surviving bacterial population that takes up the gene fragments?
As the bacterial populations grow, bacteria divide regularly. For each cell division, the genome is duplicated and passed on to the two daughter cells. Errors creep in regularly during this recurrent process. Only efficient repair mechanisms, including the exchange of flawless genetic material, can prevent the accumulation of genetic aberrations. In short: The genetic material is kept fresh.
“A further evolutionary advantage of gene transfer agents is the spread of new genetic material throughout the bacterial population, endowing it with new properties. This may also include antibiotic resistance”, explains Dehio. But this survival advantage for bacteria means, on the other hand, a threat to humans.
Only the fittest bacteria transfer genes
It has long remained unknown how the exchange of genetic material between bacteria using gene transfer agents works and how it is regulated. In their study, Dehio’s team has comprehensively identified the involved components. In particular, stress signals are key players in this process. Only bacteria in good condition exchange genetic material, whereas bacteria stressed as a result of unfavorable gene mutations do not transfer genes.
“In other words only the fittest and genetically most promising bacteria in a population divide and exchange genetic material. In genetically weakened and therefore stressed bacteria this mechanism is switched off”, says Maxime Québatte, the first author of the study.
The sharing of intact genetic material endows the fittest part of a bacterial population to persist in the host and to be passed onto new hosts successfully. This knowledge may, in turn, be used to develop new strategies to combat infections caused by the pathogen Bartonella.
Maxime Québatte, Matthias Christen, Alexander Harms, Jonas Körner, Beat Christen, and Christoph Dehio
Gene transfer agent promotes evolvability within the fittest subpopulation of a bacterial pathogen
Cell Systems (2017), doi: 10.1016/j.cels.2017.05.011
Prof. Dr. Christoph Dehio, University of Basel, Biozentrum, Tel. +41 61 207 21 40, email: firstname.lastname@example.org
Heike Sacher, University of Basel, Biozentrum, Communications, Tel. +41 61 207 14 49, email: email@example.com
Heike Sacher | Universität Basel
Ambush in a petri dish
24.11.2017 | Friedrich-Schiller-Universität Jena
Meadows beat out shrubs when it comes to storing carbon
23.11.2017 | Norwegian University of Science and Technology
High-precision measurement of the g-factor eleven times more precise than before / Results indicate a strong similarity between protons and antiprotons
The magnetic moment of an individual proton is inconceivably small, but can still be quantified. The basis for undertaking this measurement was laid over ten...
Heat from the friction of rocks caused by tidal forces could be the “engine” for the hydrothermal activity on Saturn's moon Enceladus. This presupposes that...
The WHO reports an estimated 429,000 malaria deaths each year. The disease mostly affects tropical and subtropical regions and in particular the African continent. The Fraunhofer Institute for Silicate Research ISC teamed up with the Fraunhofer Institute for Molecular Biology and Applied Ecology IME and the Institute of Tropical Medicine at the University of Tübingen for a new test method to detect malaria parasites in blood. The idea of the research project “NanoFRET” is to develop a highly sensitive and reliable rapid diagnostic test so that patient treatment can begin as early as possible.
Malaria is caused by parasites transmitted by mosquito bite. The most dangerous form of malaria is malaria tropica. Left untreated, it is fatal in most cases....
The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.
Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...
Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.
That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...
15.11.2017 | Event News
15.11.2017 | Event News
30.10.2017 | Event News
24.11.2017 | Physics and Astronomy
24.11.2017 | Health and Medicine
24.11.2017 | Earth Sciences