ruvB
Domain
Has 3 domains, the large (RuvB-L) and small ATPase (RuvB-S) domains and the C-terminal head (RuvB-H) domain. The head domain binds DNA, while the ATPase domains jointly bind ATP, ADP or are empty depending on the state of the subunit in the translocation cycle. During a single DNA translocation step the structure of each domain remains the same, but their relative positions change.
Function
The RuvABC complex is involved in recombinational repair of UV or chemically damaged DNA (PubMed:6374379). The complex also plays an important role in the rescue of blocked DNA replication forks via replication fork reversal (RFR); RFR and homologous recombination required for UV light survival can be separated (PubMed:16424908, PubMed:18942176, PubMed:9814711). This subunit has a weak ATPase activity that is inhibited by its ADP product; binds ADP better than ATP (PubMed:2529252). Promotes Holliday junction (HJ) branch migration in conjunction with RuvA. Binds to HJ cruciform DNA; in the presence of RuvA, ATP and Mg(2+) the junction is dissociated. Hydrolyzable (d)NTPs can replace ATP but other analogs cannot (PubMed:1608954, PubMed:1617728, PubMed:6374379, PubMed:8393934). The RuvB hexamer acts as a pump, pulling DNA into and through the RuvAB complex (PubMed:9078376). Can bypass UV-induced lesions (PubMed:1617728) and physically cross-linked DNA strands (PubMed:10662672), suggesting RuvB does not unwind large sections of DNA. RuvA gives specificity by binding to cruciform junctions, while the RuvB ATPase provides the motor force for branch migration; excess RuvB can promote branch migration in the absence of RuvA (PubMed:10662672, PubMed:1617728). In vitro the RuvA-RuvB complex has 5'-3' helicase activity that is ATP-dependent and works best on short dsDNA hybrids; 52 and 66-nucleotide (nt) pairs are easily displaced, hybrids greater than 140-nts are not (PubMed:8433990). RuvA stimulates the weak ATPase activity of RuvB in the presence of DNA; HJ DNA stimulates ATPase about 10-fold (PubMed:1435721, PubMed:1833759, PubMed:8393934).
An in vitro resolvase system that forms and processes HJ has been reconstituted with DNA substrates, RuvA, RuvB and RuvC. RuvA-RuvB increases the rate of strand exchange (branch migration), dissociates the RecA filament and allows RuvC to cleave in both orientations at the cruciform junction (PubMed:10421637, PubMed:9160752). HJ-RuvA-RuvB-RuvC complexes resolve Holliday junctions and also undergo branch migration, providing evidence for a coupled branch migration/HJ resolution reaction (PubMed:10421637).
Sequence Similarities
Belongs to the RuvB family.
Cellular localization
- Cytoplasm
- In 15% of cell localizes to discrete nucleoid foci (probable DNA damage sites) upon treatment with mitomycin C (MMC) for 2 hours.
Alternative names
b1860, JW1849, ruvB, Holliday junction branch migration complex subunit RuvB