SOSinduced

SOSinduced is a term used in microbiology to describe genes, proteins, or phenotypes whose expression is upregulated as part of the bacterial SOS response to DNA damage. The SOS response is a regulatory network that coordinates DNA repair, replication restart, and cell-cycle control in many bacteria.

In many bacteria, DNA damage leads to the accumulation of single-stranded DNA, which activates RecA. Activated RecA promotes autocleavage of the LexA repressor, lifting repression of the SOS regulon. This results in increased transcription of a broad set of SOSinduced genes. The composition of the regulon varies among species but commonly includes genes involved in nucleotide excision repair, recombination, translesion synthesis, and cell-cycle control.

Prominent examples of SOSinduced components include sulA, which inhibits cell division and causes filamentation; umuD and umuC, which form the error-prone DNA polymerase V (UmuD'2C) to bypass lesions; and recA itself, along with other repair factors such as recN. Additional SOSinduced genes often encode regulatory proteins, DNA helicases, and recombination enzymes. The extent of induction can be rapid and is typically transient, diminishing as DNA repair proceeds and LexA reaccumulates.

Terminology aside, SOSinduced generally refers to elements upregulated under the SOS response. It is often used interchangeably with “SOS-induced,” though some literature prefers the hyphenated form. The concept is central to understanding bacterial mutagenesis, antibiotic tolerance, and stress responses, and is primarily studied in prokaryotes where the LexA-RecA regulatory axis is well characterized.

See also: SOS response; LexA; RecA; DNA damage repair; mutagenesis.