SOS response

SOS response is a global DNA repair mechanism in bacteria that is activated in response to significant DNA damage. The name is derived from the international Morse code distress signal ('''SOS'''), and is used here to indicate a state of emergency within the cell.

Overview

The SOS response is a cellular process that involves a coordinated response to DNA damage, which includes DNA repair, cell cycle arrest, and potentially programmed cell death if the damage is too severe. The response is regulated by a number of genes, including recA and lexA, which are responsible for the initiation and termination of the response, respectively.

Mechanism

The SOS response is initiated when single-stranded DNA (ssDNA) accumulates in the cell. This can occur as a result of DNA damage, such as that caused by ultraviolet light or chemical mutagens. The ssDNA is bound by the RecA protein, which stimulates the self-cleavage and inactivation of the LexA repressor protein. This allows for the expression of the SOS genes, which include those involved in DNA repair, cell cycle arrest, and programmed cell death.

Role in bacterial survival

The SOS response plays a crucial role in the survival of bacteria in the face of DNA damage. By coordinating a response that includes DNA repair and cell cycle arrest, the SOS response allows the cell time to repair the damage before it is passed on to daughter cells. If the damage is too severe, the SOS response can trigger programmed cell death, preventing the propagation of severely damaged cells.

Role in bacterial evolution

The SOS response also plays a role in bacterial evolution, as it can increase the mutation rate in response to DNA damage. This can lead to the evolution of antibiotic resistance in bacteria, as well as the evolution of new traits that can help the bacteria survive in changing environments.

See also

• DNA repair
• RecA
• LexA
• Programmed cell death
• Antibiotic resistance

SOS response Resources
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