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: email@example.com
Heike Sacher, University of Basel, Biozentrum, Communications, Tel. +41 61 207 14 49, email: firstname.lastname@example.org
Heike Sacher | Universität Basel
UNH researchers create a more effective hydrogel for healing wounds
21.11.2018 | University of New Hampshire
Removing toxic mercury from contaminated water
21.11.2018 | Chalmers University of Technology
Innsbruck quantum physicists have constructed a diode for magnetic fields and then tested it in the laboratory. The device, developed by the research groups led by the theorist Oriol Romero-Isart and the experimental physicist Gerhard Kirchmair, could open up a number of new applications.
Electric diodes are essential electronic components that conduct electricity in one direction but prevent conduction in the opposite one. They are found at the...
Max Planck researchers revel the nano-structure of molecular trains and the reason for smooth transport in cellular antennas.
Moving around, sensing the extracellular environment, and signaling to other cells are important for a cell to function properly. Responsible for those tasks...
Researchers at the University of New Hampshire have captured a difficult-to-view singular event involving "magnetic reconnection"--the process by which sparse particles and energy around Earth collide producing a quick but mighty explosion--in the Earth's magnetotail, the magnetic environment that trails behind the planet.
Magnetic reconnection has remained a bit of a mystery to scientists. They know it exists and have documented the effects that the energy explosions can...
Biochips have been developed at TU Wien (Vienna), on which tissue can be produced and examined. This allows supplying the tissue with different substances in a very controlled way.
Cultivating human cells in the Petri dish is not a big challenge today. Producing artificial tissue, however, permeated by fine blood vessels, is a much more...
Faster and secure data communication: This is the goal of a new joint project involving physicists from the University of Würzburg. The German Federal Ministry of Education and Research funds the project with 14.8 million euro.
In our digital world data security and secure communication are becoming more and more important. Quantum communication is a promising approach to achieve...
19.11.2018 | Event News
09.11.2018 | Event News
06.11.2018 | Event News
21.11.2018 | Life Sciences
21.11.2018 | Medical Engineering
21.11.2018 | Physics and Astronomy