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- The ability of a cell to successfully incorporate exogenous DNA, or competency, is determined by competence factors. These factors consist of certain cell surface proteins and transcription factors that induce the uptake of DNA. Natural competence is the ability of a cell to bind to and transport extracellular DNA through the membrane and recombine foreign genes into its own DNA through a process called transformation. Horizontal gene transfer is a result of this, where bacterial genes can be transferred amongst same-generation species in a given environment, and competence is the ability of a cell to participate in the transfer. If one cell in a population living in an unfavorable environment has a mutation that results in better survivability, that gene can be passed on to other competent cells to extend the same advantage. Plasmids, commonly used in genetic manipulation, can also be shared through horizontal gene transfer, which is especially relevant in modern medicine concerning the exchange of antibiotic-resistant plasmids. A cell's competence can be determined by its genetics, which is the case for natural competency, or it can be manipulated in order to achieve artificial competence. There are two types of competence-inducing pheromones, these are ComX and CSF. ComX is a ten amino acid oligopeptide; it requires two co-components, ComP, an histidine kinase, and ComA, a cytoplasmic response regulator. ComX binds to ComP on the outside of the inner membrane; ComP autophosphorylates and the phosphoric group is transferred to ComA. This activates transcription of genes in the competence pathway. CSF is a five amino acid oligopeptide and is exported via the GSP pathway. CSF enters the cell through oligopeptide permeate and stimulates the competence pathway at low concentrations (1-5 nM); at high concentrations (>20 nM) competence is inhibited and sporulation is stimulated. (en)
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