Natural competence

In microbiology, genetics, cell biology, and molecular biology, competence is the ability of a cell to take up extracellular ("naked") DNA from its environment in the process called transformation. Competence may be differentiated between natural competence, a genetically specified ability of bacteria which is thought to occur under natural conditions as well as in the laboratory, and induced or artificial competence, which arises when cells in laboratory cultures are treated to make them transiently permeable to DNA. This article primarily deals with natural competence in bacteria, although information about artificial competence is also provided.

Natural competence was discovered by Frederick Griffith in 1928, when he showed that a preparation of killed cells of a pathogenic bacterium contained something that could transform related non-pathogenic cells into the pathogenic type. In 1944 Oswald Avery, Colin MacLeod, and Maclyn McCarty demonstrated that this 'transforming factor' was pure DNA . This was the first compelling evidence that DNA carries the genetic information of the cell.

Since then, natural competence has been studied in a number of different bacteria, particularly Bacillus subtilis, (Griffith's "pneumococcus"), Neisseria gonorrhoeae and Haemophilus influenzae. Areas of active research include the mechanisms of DNA transport, the regulation of competence in different bacteria, and the evolutionary function of competence.

In the natural world DNA usually becomes available by death and lysis of other cells, but in the laboratory it is provided by the researcher, often as a genetically engineered fragment or plasmid. During uptake, DNA is transported across the cell membrane(s), and the cell wall if one is present. Once the DNA is inside the cell it may be degraded to nucleotides, which are reused for DNA replication and other metabolic functions. Alternatively it may be recombined into the cell’s genome by its DNA repair enzymes. If this recombination changes the cell’s genotype the cell is said to have been transformed. Artificial competence and transformation are used as research tools in many organisms (see Transformation (genetics)).

...
Wikipedia