RecD is the fast 5-prime-to-3-prime ATP-dependent DNA helicase motor of the bacterial RecBCD complex. Together with the oppositely directed RecB motor and the RecC scaffold, it drives processive double-strand-end unwinding and modulates RecB nuclease and RecA-loading activities. RecD contributes to, but does not itself catalyze, Exonuclease V nuclease chemistry. In the experimentally studied pseudomonad Pseudomonas syringae, RecD is required for resistance to UV and mitomycin C, unlike the dispensable RecD subunit in the corresponding Escherichia coli assays.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0000724 double-strand break repair via homologous recombination | IEA GO_REF:0000104 | ACCEPT | Summary: The RecD motor is required for productive RecBCD-dependent homologous double-strand-break repair in pseudomonads. Reason: The target record assigns RecD to recombinational end processing, and P. syringae recD mutants are UV- and mitomycin-C-sensitive; this contrasts with E. coli and supports retaining RecD as a core pseudomonad repair subunit. Supporting Evidence: PMID:20195537 sensitive to DNA-damaging agents and fail to grow at 4 degrees C. file:PSEPK/recD/recD-uniprot.txt facilitates RecA-binding to the ssDNA for homologous DNA recombination |
| GO:0003677 DNA binding | IEA GO_REF:0000104 | KEEP AS NON CORE | Summary: RecD contacts DNA in the RecBCD holoenzyme, although DNA binding alone does not define its motor role. Reason: The target record explicitly says that every RecBCD subunit contributes to DNA binding; the directional helicase term remains the informative core molecular function. Supporting Evidence: file:PSEPK/recD/recD-uniprot.txt All subunits contribute to DNA-binding. |
| GO:0004386 helicase activity | IEA GO_REF:0000002 | KEEP AS NON CORE | Summary: RecD genuinely has helicase activity, but this generic term is less informative than its directional motor assignment. Reason: Retain the true broad molecular function while using GO:0043139, 5-prime-to-3-prime DNA helicase activity, as the defining core term. Supporting Evidence: file:PSEPK/recD/recD-uniprot.txt ssDNA-dependent ATPase and 5'-3' helicase activity. |
| GO:0005524 ATP binding | IEA GO_REF:0000104 | ACCEPT | Summary: ATP binding is intrinsic to the RecD ATPase-helicase motor. Reason: The target record assigns RecD an ATP-hydrolysis reaction and ATP-dependent 5-prime-to-3-prime helicase activity. Supporting Evidence: file:PSEPK/recD/recD-uniprot.txt Reaction=ATP + H2O = ADP + phosphate + H(+) |
| GO:0006302 double-strand break repair | IEA GO_REF:0000002 | KEEP AS NON CORE | Summary: RecD participates in double-strand-break repair, but GO:0000724 captures the homologous-recombination route more precisely. Reason: P. syringae recD mutants are sensitive to UV and mitomycin C and lose RecBCD recombination proficiency, providing direct pseudomonad support for the broad process while the more specific homologous-repair term remains core. Supporting Evidence: PMID:20195537 sensitive to DNA-damaging agents and fail to grow at 4 degrees C. |
| GO:0006310 DNA recombination | IEA GO_REF:0000120 | ACCEPT | Summary: RecD powers the RecBCD end-processing pathway that initiates homologous DNA recombination. Reason: The target record links RecD-containing holoenzyme activity to RecA loading, and pseudomonad RecBCD clones confer recombination proficiency. Supporting Evidence: PMID:2559208 Three clones from Pseudomonas aeruginosa and Ps. putida conferred recombination proficiency and ATP-dependent nuclease activity file:PSEPK/recD/recD-uniprot.txt facilitates RecA-binding to the ssDNA for homologous DNA recombination |
| GO:0008854 exodeoxyribonuclease V activity | IEA GO_REF:0000002 | MARK AS OVER ANNOTATED | Summary: RecD stimulates and contributes to Exonuclease V activity but does not independently catalyze nuclease chemistry. Reason: The `enables` qualifier incorrectly attributes the holoenzyme's nuclease reaction directly to RecD. The target record states that RecD stimulates RecBC nuclease activity; the catalytic nuclease site is in RecB. Supporting Evidence: file:PSEPK/recD/recD-uniprot.txt assembled RecBC greatly stimulates nuclease activity and augments |
| GO:0009338 exodeoxyribonuclease V complex | IEA GO_REF:0000120 | ACCEPT | Summary: RecD is the 5-prime-to-3-prime motor subunit of the Exonuclease V complex. Reason: The target record explicitly identifies the RecB-RecC-RecD heterotrimer, and pseudomonad genetic evidence shows that RecD loss functionally disables RecBCD. Supporting Evidence: file:PSEPK/recD/recD-uniprot.txt Heterotrimer of RecB, RecC and RecD. PMID:20195537 The RecD requirement is only a function of the RecBCD complex |
| GO:0016887 ATP hydrolysis activity | IEA GO_REF:0000120 | ACCEPT | Summary: RecD hydrolyzes ATP to power its directional DNA motor. Reason: The target record supplies the explicit Rhea ATP-hydrolysis reaction and identifies RecD as an ssDNA-dependent ATPase. Supporting Evidence: file:PSEPK/recD/recD-uniprot.txt Reaction=ATP + H2O = ADP + phosphate + H(+) |
| GO:0017116 single-stranded DNA helicase activity | IEA GO_REF:0000118 | KEEP AS NON CORE | Summary: RecD has directly supported single-stranded-DNA-dependent helicase activity, a substrate-axis description distinct from motor directionality. Reason: GO:0017116 is not a parent of the 5-prime-to-3-prime term and is biologically true, but GO:0043139 better captures RecD's defining polarity in the core-function summary. Supporting Evidence: file:PSEPK/recD/recD-uniprot.txt ssDNA-dependent ATPase and 5'-3' helicase activity. |
| GO:0043139 5'-3' DNA helicase activity | IEA GO_REF:0000120 | ACCEPT | Summary: RecD is the fast 5-prime-to-3-prime DNA helicase motor of RecBCD. Reason: The target record explicitly assigns 5-prime-to-3-prime helicase activity to this RecD family protein and describes ATP-coupled translocation in that direction. Supporting Evidence: file:PSEPK/recD/recD-uniprot.txt ssDNA-dependent ATPase and 5'-3' helicase activity. |
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Download this section (compressed HTML)Q: How do RecD motor speed and ATPase activity tune RecA loading and the resection-mode switch in the KT2440 RecBCD complex?
Experiment: Test a clean recD deletion for double-strand-break repair, homologous recombination, and RecA loading, then complement with wild-type protein.
Type: genetic pathway validation
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