UvrABC system protein C (UvrC, excinuclease ABC subunit C) is the catalytic endonuclease subunit of the bacterial UvrABC excinuclease that performs nucleotide excision repair (NER), the pathway that removes a broad range of bulky, helix-distorting DNA lesions. After UvrA and UvrB recognize damage and load UvrB onto the lesion site, UvrC is recruited to the UvrB-DNA pre-incision complex and makes the dual incision that brackets the lesion on the damaged strand: an N-terminal GIY-YIG nuclease domain catalyzes the 3' incision and a C-terminal RNase H-like nuclease domain catalyzes the 5' incision, releasing a short damage-containing oligonucleotide that is subsequently removed and the gap filled and ligated. UvrC carries a GIY-YIG endonuclease domain, a central UVR domain that mediates interaction with UvrB, and helix-hairpin-helix (HhH) DNA-binding motifs. It acts on chromosomal DNA in the cytoplasm. The protein is 607 residues, highly conserved across bacteria, and in P. putida KT2440 is encoded by PP_4098.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0003677 DNA binding | IEA GO_REF:0000120 | KEEP AS NON CORE | Summary: UvrC binds DNA at the lesion site via its helix-hairpin-helix (HhH) motifs to position the strand for dual incision. The annotation is correct but generic; DNA binding is a means to the catalytic endonuclease function rather than a core molecular function on its own. Reason: Direct DNA contact is correct and consistent with the HhH motifs, but it does not establish UvrA/UvrB-like damaged-DNA recognition. It is retained as non-core context while GO:0004520 captures UvrC's independent catalytic function and GO:0009381 is represented only as a complex contribution. |
| GO:0005737 cytoplasm | IEA GO_REF:0000120 | ACCEPT | Summary: UvrC acts on chromosomal DNA in the cytoplasm/nucleoid. Cytoplasmic localization is consistent with UniProt subcellular location and the role of NER in repairing the bacterial chromosome. Reason: Correct localization for a soluble DNA-repair endonuclease; no evidence of membrane, secreted, or extracellular localization. |
| GO:0006281 DNA repair | IEA GO_REF:0000120 | KEEP AS NON CORE | Summary: UvrC is a core DNA repair enzyme. This high-level term is correct but subsumed by the more specific nucleotide-excision repair annotation. Reason: True but general; the specific child term GO:0006289 (nucleotide-excision repair) better captures the biological process. |
| GO:0006289 nucleotide-excision repair | IEA GO_REF:0000120 | ACCEPT | Summary: UvrC is the dual-incision endonuclease of the bacterial UvrABC NER system, performing the strand incisions that excise lesion-containing oligonucleotides. This is the core biological process for this protein. Reason: Directly supported by the conserved UvrC family role, domain architecture (GIY-YIG plus RNase H-like nuclease), and UniProt FUNCTION annotation. |
| GO:0006974 DNA damage response | IEA GO_REF:0000120 | KEEP AS NON CORE | Summary: As a DNA repair enzyme UvrC participates in the cellular response to DNA damage. This is a broad parent term subsumed by the more specific NER and DNA repair annotations. Reason: Correct but high-level/generic; the specific NER role is the informative annotation. |
| GO:0009380 excinuclease repair complex | IEA GO_REF:0000120 | ACCEPT | Summary: UvrC is recruited to and acts within the UvrABC excinuclease (pre-incision) complex, interacting with UvrB at the lesion. Membership in this complex is consistent with the UVR domain (UniProt SUBUNIT note) that mediates UvrB interaction. Reason: Correct cellular component for the catalytic subunit of the UvrABC excinuclease. |
| GO:0009381 excinuclease ABC activity | IEA GO_REF:0000120 | MARK AS OVER ANNOTATED | Summary: GO:0009381 describes the dual-incision chemistry of the assembled UvrABC system. UvrC supplies its endonuclease chemistry but does not independently enable the complete complex activity. Reason: The `enables` qualifier overstates the individual subunit. UvrC enables endonuclease activity and contributes that chemistry to UvrABC excinuclease activity. Supporting Evidence: file:PSEPK/uvrC/uvrC-uniprot.txt UvrC both incises the 5' and 3' sides |
| GO:0004520 DNA endonuclease activity | ISS UniProtKB:P0A8G0 | NEW | Summary: UvrC catalyzes the two strand incisions that bracket a lesion during bacterial nucleotide-excision repair. Reason: This DNA-specific leaf molecular-function term captures the nuclease chemistry supplied independently by UvrC without assigning the complete UvrABC complex activity to one subunit. Supporting Evidence: file:PSEPK/uvrC/uvrC-uniprot.txt UvrC both incises the 5' and 3' sides |
| GO:0009432 SOS response | IEA GO_REF:0000104 | KEEP AS NON CORE | Summary: uvrA, uvrB, and uvrC are members of the LexA-controlled SOS regulon in E. coli and other bacteria, with uvr expression induced upon DNA damage. Annotation by homology transfer is plausible for P. putida UvrC, though participation in the SOS response is regulatory/contextual rather than a direct molecular activity, and KT2440-specific induction has not been verified here. Reason: Plausible regulon membership inherited by homology; reflects induction/regulatory context rather than the core enzymatic function. Retained as non-core given it is a generic IEA transfer not experimentally confirmed in this organism. |
Loading supporting content…
Download this section (compressed HTML)Q: Is uvrC in P. putida KT2440 transcriptionally induced as part of the LexA/SOS regulon upon DNA damage, and is it co-regulated within the predicted pp4100-gacA-uvrC-pgsA operon context?
Experiment: Construct a P. putida KT2440 uvrC deletion mutant and measure UV and bulky-adduct (e.g., mitomycin C, formaldehyde) sensitivity to confirm the NER incision role in this organism.
Loading supporting content…
Download this section (compressed HTML)Loading supporting content…
Download this section (compressed HTML)