scholarly journals Genetic dominance governs the evolution and spread of mobile genetic elements in bacteria

2020 ◽  
Vol 117 (27) ◽  
pp. 15755-15762
Author(s):  
Jerónimo Rodríguez-Beltrán ◽  
Vidar Sørum ◽  
Macarena Toll-Riera ◽  
Carmen de la Vega ◽  
Rafael Peña-Miller ◽  
...  
Keyword(s):  
Antibiotic Resistance ◽  
Mobile Genetic Elements ◽  
Model System ◽  
Host Bacterium ◽  
Wild Type ◽  
Bacterial Evolution ◽  
Human Interest ◽  
Genetic Dominance ◽  
Genetic Elements

Mobile genetic elements (MGEs), such as plasmids, promote bacterial evolution through horizontal gene transfer (HGT). However, the rules governing the repertoire of traits encoded on MGEs remain unclear. In this study, we uncovered the central role of genetic dominance shaping genetic cargo in MGEs, using antibiotic resistance as a model system. MGEs are typically present in more than one copy per host bacterium, and as a consequence, genetic dominance favors the fixation of dominant mutations over recessive ones. In addition, genetic dominance also determines the phenotypic effects of horizontally acquired MGE-encoded genes, silencing recessive alleles if the recipient bacterium already carries a wild-type copy of the gene. The combination of these two effects governs the catalog of genes encoded on MGEs. Our results help to understand how MGEs evolve and spread, uncovering the neglected influence of genetic dominance on bacterial evolution. Moreover, our findings offer a framework to forecast the spread and evolvability of MGE-encoded genes, which encode traits of key human interest, such as virulence or antibiotic resistance.

scholarly journals Genetic dominance governs the evolution and spread of mobile genetic elements in bacteria

2019 ◽  
Author(s):  
Jerónimo Rodríguez-Beltrán ◽  
Vidar Sørum ◽  
Macarena Toll-Riera ◽  
Carmen de la Vega ◽  
Rafael Peña-Miller ◽  
...  
Keyword(s):  
Antibiotic Resistance ◽  
Horizontal Gene Transfer ◽  
Mobile Genetic Elements ◽  
Model System ◽  
Host Bacterium ◽  
Wild Type ◽  
Bacterial Evolution ◽  
Genetic Dominance ◽  
Genetic Elements

AbstractMobile genetic elements (MGEs), such as plasmids, promote bacterial evolution through horizontal gene transfer (HGT). However, the rules governing the repertoire of traits encoded on MGEs remain unclear. In this study, we uncovered the central role of genetic dominance shaping genetic cargo in MGEs, using antibiotic resistance as a model system. MGEs are typically present in more than one copy per host bacterium and, as a consequence, genetic dominance favors the fixation of dominant mutations over recessive ones. Moreover, genetic dominance also determines the phenotypic effects of horizontally acquired MGE-encoded genes, silencing recessive alleles if the recipient bacterium already carries a wild-type copy of the gene. The combination of these two effects governs the catalogue of genes encoded on MGEs, dictating bacterial evolution through HGT.

scholarly journals Black Queen Evolution and Trophic Interactions Determine Plasmid Survival after the Disruption of the Conjugation Network

mSystems ◽  
2018 ◽  
Vol 3 (5) ◽  
Author(s):  
Johannes Cairns ◽  
Katariina Koskinen ◽  
Reetta Penttinen ◽  
Tommi Patinen ◽  
Anna Hartikainen ◽  
...  
Keyword(s):  
Antibiotic Resistance ◽  
Bacterial Communities ◽  
Resistance Mechanism ◽  
Real Life ◽  
Ecological Factors ◽  
Mobile Genetic Elements ◽  
Resistance Mechanisms ◽  
Antibiotics Resistance ◽  
Bacterial Populations ◽  
Genetic Elements

ABSTRACTMobile genetic elements such as conjugative plasmids are responsible for antibiotic resistance phenotypes in many bacterial pathogens. The ability to conjugate, the presence of antibiotics, and ecological interactions all have a notable role in the persistence of plasmids in bacterial populations. Here, we set out to investigate the contribution of these factors when the conjugation network was disturbed by a plasmid-dependent bacteriophage. Phage alone effectively caused the population to lose plasmids, thus rendering them susceptible to antibiotics. Leakiness of the antibiotic resistance mechanism allowing Black Queen evolution (i.e. a “race to the bottom”) was a more significant factor than the antibiotic concentration (lethal vs sublethal) in determining plasmid prevalence. Interestingly, plasmid loss was also prevented by protozoan predation. These results show that outcomes of attempts to resensitize bacterial communities by disrupting the conjugation network are highly dependent on ecological factors and resistance mechanisms.IMPORTANCEBacterial antibiotic resistance is often a part of mobile genetic elements that move from one bacterium to another. By interfering with the horizontal movement and the maintenance of these elements, it is possible to remove the resistance from the population. Here, we show that a so-called plasmid-dependent bacteriophage causes the initially resistant bacterial population to become susceptible to antibiotics. However, this effect is efficiently countered when the system also contains a predator that feeds on bacteria. Moreover, when the environment contains antibiotics, the survival of resistance is dependent on the resistance mechanism. When bacteria can help their contemporaries to degrade antibiotics, resistance is maintained by only a fraction of the community. On the other hand, when bacteria cannot help others, then all bacteria remain resistant. The concentration of the antibiotic played a less notable role than the antibiotic used. This report shows that the survival of antibiotic resistance in bacterial communities represents a complex process where many factors present in real-life systems define whether or not resistance is actually lost.

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