The following text describes a protein:
Function:
The RuvA-RuvB-RuvC complex processes Holliday junction (HJ) DNA during genetic recombination and DNA repair. The RuvA-RuvB complex 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. The RuvA-RuvB complex promotes Holliday junction (HJ) branch migration. RuvA binds to HJ cruciform DNA, conferring on it an open structure. In the presence of RuvB, ATP and Mg(2+) the junction is dissociated; hydrolyzable (d)NTPs can replace ATP but other analogs cannot. The RuvB hexamer acts as a pump, pulling dsDNA into and through the RuvAB complex. Can bypass UV-induced lesions and physically cross-linked DNA strands. 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. Overexpression of RuvA alone leads to UV sensitivity. RuvA stimulates the weak ATPase activity of RuvB in the presence of DNA; the addition of HJ DNA further stimulates ATPase about 10-fold. Inhibits RuvC endoDNase activity by binding to HJ DNA, including DNA to which RuvC is already bound. Does not bind dsDNA. May act as a collar that slides at HJ which promotes branch migration while inhibiting other DNA remodeling activities (Probable); 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. HJ-RuvA-RuvB-RuvC complexes resolve Holliday junctions and also undergo branch migration, providing evidence for a coupled branch migration/HJ resolution reaction.
Subcellular Localization:
Cytoplasm. Note=In 15% of cell localizes to discrete nucleoid foci (probable DNA damage sites) upon treatment with mitomycin C (MMC) for 2 hours.
Domain:
Has three domains with a flexible linker between the domains II and III, and assumes an 'L' shape. Domain III has weak interactions with the adjacent subunit. In complex with Holliday junction (HJ) DNA, an approximately square planar DNA molecule is bound to the tetramer's concave face, with the DNA accessible to solution on one side. Domain III moves 4-5 Angstroms toward the protein-DNA interface upon DNA binding. The isolated N-terminus (domains I and II) forms tetramers and binds HJ DNA but does not bind RuvB. Alterations of bulky residues on the surface of domain III prevent binding to RuvB. Domains I and II crystallize with the same tetrameric structure and are dominant negative to wild-type in vivo. In intact protein, domain III is quite flexible in solution. Isolated domain III inhibits the ATPase activity of RuvB. The acidic pin (Glu-55 and Asp-56) seems to push the DNA backbone away from the HJ/RuvA complex center. It prevents binding to non-HJ dsDNA and constrains the rate of branch migration.
Sequence:
MIGRLRGIIIEKQPPLVLIEVGGVGYEVHMPMTCFYELPEAGQEAIVFTHFVVREDAQLLYGFNNKQERTLFKELIKTNGVGPKLALAILSGMSAQQFVNAVEREEVGALVKLPGIGKKTAERLIVEMKDRFKGLHGDLFTPAADLVLTSPASPATDDAEQEAVAALVALGYKPQEASRMVSKIARPDASSETLIREALRAAL