plasmid

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Bacteria’s toxic addiction to DNA

For bacteria, addiction to DNA can be a life or death situation. Lose that DNA and the bacterium suffers an unfortunate toxic death.

Many bacteria easily transfer DNA amongst themselves in the forms of plasmid DNA. Plasmids are mobile genetic elements that replicate independently of the chromosome. These small circular pieces of DNA often contain genes that provide its carrier a survival advantage under specific environmental conditions. For example, if a bacterium contains a plasmid with an antibiotic resistance gene, it can survive antibiotic treatment. But, the plasmid is not beneficial to its host cell in all situations and poses a metabolic burden for the host. So why do these plasmids exist and remain in bacteria? (more…)

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Solving the plasmid paradox: evolutionary advantages of multicopy plasmids

Today marks the end of 2016's World Antibiotic Awareness Week, aimed to increase awareness of antibiotic resistance and to advocate for the prudent use of these drugs.

One of the key drivers of antibiotic resistance is how rapidly bacteria acquire DNA from the environment or from other bacteria. Resistance elements are often carried on mobile elements, DNA that can move around the genome or be transferred to other genomes. The almost universal rapid assimilation of DNA by bacteria leads to the acquisition of multiple antibiotic resistance genes in a variety of bacterial species. One such example of a DNA mobile element is the plasmid, small circular DNA that replicates independently of the chromosome and can be transferred from bacterium to bacterium during cell division, transformation, and conjugation. (more…)