SOS response

traitmech:000207 · CLASS · PROPOSED

A stress response in which RecA/LexA-mediated sensing of DNA damage derepresses an SOS regulon that coordinates DNA repair, damage tolerance, transient division arrest, and mutagenic survival functions.

Trait evidence (4)

DOI:10.1002/em.22267
Most bacteria have evolved a coordinated response to DNA damage

Maslowska et al. review the bacterial SOS response as a coordinated DNA-damage response.
DOI:10.1002/em.22267
The SOS global regulatory network consists of multiple factors promoting the integrity of DNA as well as error-prone factors allowing for survival and continuous replication upon extensive DNA damage

The SOS regulon coordinates high-fidelity DNA-integrity functions with error-prone survival functions induced under extensive DNA damage.
DOI:10.1002/advs.202203260
the SOS response is activated through the binding of recA with single stranded DNA and the self-cleavage of the lexA repressor, enabling expression of SOS regulon genes

Yu et al. directly support the RecA/LexA activation branch of the SOS response.
DOI:10.1002/advs.202203260
cell division inhibitor, sulA, blocks FtsZ (a master regulator of bacterial cell division and responsible for the Z ring formation at mid-cell) polymerization

Yu et al. support SOS-induced division inhibition as one physiological output of the response.

DNA-damage SOS regulon induction

Evidence-backed causal sketch linking DNA damage and single-stranded DNA accumulation to RecA/LexA derepression of SOS-regulon functions.

MECHANISTIC · This graph captures the classical E. coli RecA/LexA branch of SOS induction. It does not make every SOS-regulon member, error-prone polymerase, or prophage-induction branch universal across bacteria.

Edge evidence

genotoxic stress causes single-stranded DNA accumulation biolink:causes
Genotoxic stress and replication inhibition expose single-stranded DNA that initiates the SOS cascade.
- DOI:10.1073/pnas.2407832121 AZT increases the burden of ssDNA at the replication fork and induces the SOS response via the RecAFOR pathway Verified against the open PNAS/PMC full text; the replication inhibitor AZT raises single-stranded DNA at replication forks and induces SOS through RecFOR.
single-stranded DNA accumulation activates RecA nucleoprotein filament RO:0002213
Single-stranded DNA supports activated RecA nucleoprotein filament formation.
- https://rest.uniprot.org/uniprotkb/P0A7G6.json Polymerizes non-specifically on ssDNA to form filaments; filament formation requires ATP or ATP-gamma-S Verified against the live UniProt REST entry for P0A7G6 retrieved on 2026-09-15.
RecA nucleoprotein filament promotes LexA autoproteolysis RO:0002213
Activated RecA promotes LexA autocleavage.
- DOI:10.1002/advs.202203260 the SOS response is activated through the binding of recA with single stranded DNA and the self-cleavage of the lexA repressor Verified against the open Wiley full text during the cell-length graph curation; the source links RecA-ssDNA to LexA self-cleavage.
LexA repressor negatively regulates SOS regulon expression RO:0002212
LexA represses SOS-regulon expression before it is inactivated.
- https://rest.uniprot.org/uniprotkb/P0A7C2.json Represses a number of genes involved in the response to DNA damage (SOS response), including recA and lexA Verified against the live UniProt REST entry for P0A7C2 retrieved on 2026-09-15.
LexA autoproteolysis derepresses SOS regulon expression
LexA autocleavage disrupts DNA binding and releases repression of SOS genes.
- https://rest.uniprot.org/uniprotkb/P0A7C2.json disrupts the DNA-binding part of LexA, leading to derepression of the SOS regulon Verified against the live UniProt REST entry for P0A7C2 retrieved on 2026-09-15.
SOS regulon expression contributes to DNA repair and damage tolerance RO:0002326
SOS-regulon expression coordinates DNA-integrity and damage-tolerance functions.
- DOI:10.1002/em.22267 multiple factors promoting the integrity of DNA as well as error-prone factors allowing for survival and continuous replication upon extensive DNA damage Verified against the public Crossref abstract; SOS-regulon functions span DNA integrity and error-prone survival.
DNA repair and damage tolerance confers SOS response METPO:2007700
The induced repair and damage-tolerance program realizes the SOS-response trait.
- DOI:10.1002/em.22267 Most bacteria have evolved a coordinated response to DNA damage Verified against the public Crossref abstract; the SOS response is an induced, coordinated bacterial DNA-damage response.

Protein and taxon examples

Graph node Protein Taxon UniProt status Role and evidence

RecA nucleoprotein filament

Graph node	Protein	Taxon	UniProt status	Role and evidence
RecA nucleoprotein filament	`UniProtKB:P0A7G6` Protein RecA (recA)	Escherichia coli K-12 `NCBITaxon:83333`	`REVIEWED` retrieved 2026-09-15 · entry v168 · sequence v2	E. coli K-12 RecA polymerizes on single-stranded DNA and activates LexA autoproteolysis during SOS induction. `https://rest.uniprot.org/uniprotkb/P0A7G6.json` Interacts with and activates LexA leading to autocatalytic cleavage of LexA, which derepresses the SOS regulon Verified against the live UniProt REST entry for P0A7G6 retrieved on 2026-09-15.
LexA repressor	`UniProtKB:P0A7C2` LexA repressor (lexA)	Escherichia coli K-12 `NCBITaxon:83333`	`REVIEWED` retrieved 2026-09-15 · entry v160 · sequence v1	E. coli K-12 LexA represses SOS genes and undergoes RecA-stimulated autocleavage to derepress the SOS regulon. `https://rest.uniprot.org/uniprotkb/P0A7C2.json` RecA interacts with LexA causing an autocatalytic cleavage which disrupts the DNA-binding part of LexA, leading to derepression of the SOS regulon Verified against the live UniProt REST entry for P0A7C2 retrieved on 2026-09-15.

UniProtKB:P0A7G6
Protein RecA (recA)

Escherichia coli K-12
NCBITaxon:83333

REVIEWED
retrieved 2026-09-15 · entry v168 · sequence v2

E. coli K-12 RecA polymerizes on single-stranded DNA and activates LexA autoproteolysis during SOS induction.

https://rest.uniprot.org/uniprotkb/P0A7G6.json Interacts with and activates LexA leading to autocatalytic cleavage of LexA, which derepresses the SOS regulon Verified against the live UniProt REST entry for P0A7G6 retrieved on 2026-09-15.

LexA repressor

UniProtKB:P0A7C2
LexA repressor (lexA)

Escherichia coli K-12
NCBITaxon:83333

REVIEWED
retrieved 2026-09-15 · entry v160 · sequence v1

E. coli K-12 LexA represses SOS genes and undergoes RecA-stimulated autocleavage to derepress the SOS regulon.

https://rest.uniprot.org/uniprotkb/P0A7C2.json RecA interacts with LexA causing an autocatalytic cleavage which disrupts the DNA-binding part of LexA, leading to derepression of the SOS regulon Verified against the live UniProt REST entry for P0A7C2 retrieved on 2026-09-15.

Provenance

Identifier source: TraitMech local identifier
Definition source: DOI:10.1002/em.22267

Parent traits (1)

stress response traitmech:000078

Synonyms (1)

SOS system RELATED_SYNONYM · DOI:10.1002/em.22267

kg-microbe context

No kg-microbe node embedding matched this record in the 2026-04-25 deepwalk.

Canonical examples (1)

Organisms cited as exemplars of this trait. Taxon ids are NCBITaxon and link out to the NCBI record.

Escherichia coli NCBITaxon:562 DOI:10.1002/em.22267 E. coli is the canonical RecA/LexA SOS-response model reviewed by Maslowska et al.

Discussions and Knowledge Gaps (1)

Open questions attached to this trait. Seeded by just knowledge-gap-scan and curated; see the corpus-wide index.

Resolve exact ontology xrefs for organism-level microbial SOS response before adding TraitRecord xrefs.

CURATION TODO OPEN sos-response-xref-gap · raised by codex · 2026-09-15

Not yet attached to a section of this record — a curator sets attaches_to (e.g. causal_graphs#some_edge) so the gap shows beside the mechanism it concerns.

GO:0009432 SOS response exactly grounds biological-process nodes in causal graphs but is shifted from this organism-level response trait. RecA, LexA, SulA, translesion-polymerase, prophage-induction, DNA-repair, and DNA-damage terms describe narrower machinery, downstream processes, or related triggers rather than the whole microbial SOS-response phenotype.

Curation history

2026-09-15T06:22:00Z · MINTED_TRAITMECH_ID · codex
Minted SOS response as a DOI-backed stress-response TraitRecord after a repository-wide duplicate review covering ignored and hidden files; the local METPO snapshot has no active exact SOS response class and the replacement placeholder is reserved in proposals/metpo_traitmech_v84.