identifier: traitmech:000207 label: SOS response definition: 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. definition_source: DOI:10.1002/em.22267 trait_category: PHYSIOLOGY term_kind: CLASS mapping_status: PROPOSED parent_traits: - traitmech:000078 synonyms: - synonym_text: SOS system synonym_type: RELATED_SYNONYM source: DOI:10.1002/em.22267 evidence: - reference: DOI:10.1002/em.22267 snippet: Most bacteria have evolved a coordinated response to DNA damage notes: Maslowska et al. review the bacterial SOS response as a coordinated DNA-damage response. - reference: DOI:10.1002/em.22267 snippet: 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 notes: The SOS regulon coordinates high-fidelity DNA-integrity functions with error-prone survival functions induced under extensive DNA damage. - reference: DOI:10.1002/advs.202203260 snippet: 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 notes: Yu et al. directly support the RecA/LexA activation branch of the SOS response. - reference: DOI:10.1002/advs.202203260 snippet: cell division inhibitor, sulA, blocks FtsZ (a master regulator of bacterial cell division and responsible for the Z ring formation at mid-cell) polymerization notes: Yu et al. support SOS-induced division inhibition as one physiological output of the response. canonical_examples: - taxon_id: NCBITaxon:562 taxon_label: Escherichia coli note: E. coli is the canonical RecA/LexA SOS-response model reviewed by Maslowska et al. reference: DOI:10.1002/em.22267 causal_graphs: - graph_id: sos_response_dna_damage_regulon title: DNA-damage SOS regulon induction description: Evidence-backed causal sketch linking DNA damage and single-stranded DNA accumulation to RecA/LexA derepression of SOS-regulon functions. scope_status: MECHANISTIC scope_notes: 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. nodes: - node_id: sos_response_trait label: SOS response node_type: TRAIT grounding: traitmech:000207 description: Capacity to mount the bacterial SOS DNA-damage response. - node_id: genotoxic_stress label: genotoxic stress node_type: ENVIRONMENTAL_FACTOR description: Genotoxic stress or replication inhibition that exposes single-stranded DNA. - node_id: single_stranded_dna_accumulation label: single-stranded DNA accumulation node_type: BIOLOGICAL_PROCESS description: Production or exposure of single-stranded DNA after DNA damage or replication stress. - node_id: reca_nucleoprotein_filament grounding_status: REVIEWED_LABEL_ONLY grounding_notes: Reviewed activated protein state; no single taxon-agnostic family, activity, or complex term captures RecA polymerized on DNA in its SOS-inducing state. label: RecA nucleoprotein filament node_type: GENE_OR_PROTEIN description: Activated RecA filament on single-stranded DNA that stimulates LexA autoproteolysis. protein_examples: - uniprot_id: UniProtKB:P0A7G6 protein_label: Protein RecA gene_symbol: recA taxon_id: NCBITaxon:83333 taxon_label: Escherichia coli K-12 entry_status: REVIEWED retrieved_on: '2026-09-15' entry_version: 168 sequence_version: 2 role: E. coli K-12 RecA polymerizes on single-stranded DNA and activates LexA autoproteolysis during SOS induction. evidence: - reference: https://rest.uniprot.org/uniprotkb/P0A7G6.json snippet: Interacts with and activates LexA leading to autocatalytic cleavage of LexA, which derepresses the SOS regulon notes: Verified against the live UniProt REST entry for P0A7G6 retrieved on 2026-09-15. - node_id: lexa_repressor label: LexA repressor node_type: GENE_OR_PROTEIN grounding: InterPro:IPR050077 description: SOS master repressor inactivated by RecA-stimulated autoproteolysis. protein_examples: - uniprot_id: UniProtKB:P0A7C2 protein_label: LexA repressor gene_symbol: lexA taxon_id: NCBITaxon:83333 taxon_label: Escherichia coli K-12 entry_status: REVIEWED retrieved_on: '2026-09-15' entry_version: 160 sequence_version: 1 role: E. coli K-12 LexA represses SOS genes and undergoes RecA-stimulated autocleavage to derepress the SOS regulon. evidence: - reference: https://rest.uniprot.org/uniprotkb/P0A7C2.json snippet: RecA interacts with LexA causing an autocatalytic cleavage which disrupts the DNA-binding part of LexA, leading to derepression of the SOS regulon notes: Verified against the live UniProt REST entry for P0A7C2 retrieved on 2026-09-15. - node_id: lexa_autoproteolysis label: LexA autoproteolysis node_type: BIOLOGICAL_PROCESS description: RecA-stimulated autocleavage of the LexA SOS repressor. - node_id: sos_regulon_expression label: SOS regulon expression node_type: BIOLOGICAL_PROCESS description: Induced expression of LexA-repressed genes in the SOS regulon. - node_id: dna_repair_damage_tolerance label: DNA repair and damage tolerance node_type: BIOLOGICAL_PROCESS description: DNA-integrity, translesion-synthesis, mutagenesis, and division-delay functions induced by the SOS regulon. edges: - subject: genotoxic_stress predicate: causes predicate_id: biolink:causes object: single_stranded_dna_accumulation description: Genotoxic stress and replication inhibition expose single-stranded DNA that initiates the SOS cascade. evidence: - reference: DOI:10.1073/pnas.2407832121 snippet: AZT increases the burden of ssDNA at the replication fork and induces the SOS response via the RecAFOR pathway notes: Verified against the open PNAS/PMC full text; the replication inhibitor AZT raises single-stranded DNA at replication forks and induces SOS through RecFOR. - subject: single_stranded_dna_accumulation predicate: activates predicate_id: RO:0002213 object: reca_nucleoprotein_filament description: Single-stranded DNA supports activated RecA nucleoprotein filament formation. evidence: - reference: https://rest.uniprot.org/uniprotkb/P0A7G6.json snippet: Polymerizes non-specifically on ssDNA to form filaments; filament formation requires ATP or ATP-gamma-S notes: Verified against the live UniProt REST entry for P0A7G6 retrieved on 2026-09-15. - subject: reca_nucleoprotein_filament predicate: promotes predicate_id: RO:0002213 object: lexa_autoproteolysis description: Activated RecA promotes LexA autocleavage. evidence: - reference: DOI:10.1002/advs.202203260 snippet: the SOS response is activated through the binding of recA with single stranded DNA and the self-cleavage of the lexA repressor notes: Verified against the open Wiley full text during the cell-length graph curation; the source links RecA-ssDNA to LexA self-cleavage. - subject: lexa_repressor predicate: negatively regulates predicate_id: RO:0002212 object: sos_regulon_expression description: LexA represses SOS-regulon expression before it is inactivated. evidence: - reference: https://rest.uniprot.org/uniprotkb/P0A7C2.json snippet: Represses a number of genes involved in the response to DNA damage (SOS response), including recA and lexA notes: Verified against the live UniProt REST entry for P0A7C2 retrieved on 2026-09-15. - subject: lexa_autoproteolysis predicate: derepresses object: sos_regulon_expression description: LexA autocleavage disrupts DNA binding and releases repression of SOS genes. evidence: - reference: https://rest.uniprot.org/uniprotkb/P0A7C2.json snippet: disrupts the DNA-binding part of LexA, leading to derepression of the SOS regulon notes: Verified against the live UniProt REST entry for P0A7C2 retrieved on 2026-09-15. - subject: sos_regulon_expression predicate: contributes to predicate_id: RO:0002326 object: dna_repair_damage_tolerance description: SOS-regulon expression coordinates DNA-integrity and damage-tolerance functions. evidence: - reference: DOI:10.1002/em.22267 snippet: multiple factors promoting the integrity of DNA as well as error-prone factors allowing for survival and continuous replication upon extensive DNA damage notes: Verified against the public Crossref abstract; SOS-regulon functions span DNA integrity and error-prone survival. - subject: dna_repair_damage_tolerance predicate: confers predicate_id: METPO:2007700 object: sos_response_trait description: The induced repair and damage-tolerance program realizes the SOS-response trait. evidence: - reference: DOI:10.1002/em.22267 snippet: Most bacteria have evolved a coordinated response to DNA damage notes: Verified against the public Crossref abstract; the SOS response is an induced, coordinated bacterial DNA-damage response. discussions: - discussion_id: sos-response-xref-gap prompt: Resolve exact ontology xrefs for organism-level microbial SOS response before adding TraitRecord xrefs. kind: CURATION_TODO status: OPEN rationale: 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. posed_by: codex posed_date: '2026-09-15' curation_history: - timestamp: '2026-09-15T06:22:00Z' curator: codex action: MINTED_TRAITMECH_ID changes: 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. llm_assisted: true