| Type: | Binding_site | Name: | Crossover junction endodeoxyribonuclease RuvC, magnesium-binding site |
| Description: | The Escherichia coliruvC gene is involved in DNA repair and in the late step of RecE and RecF pathway recombination []. RuvC protein () cleaves cruciform junctions, which are formed by the extrusion of inverted repeat sequences from a super-coiled plasmid and which are structurally analogous to Holliday junctions, by introducing nicks into strands with the same polarity. The nicks leave a 5'terminal phosphate and a 3'terminal hydroxyl group which are ligated by E. coli or Bacteriophage T4DNA ligases. Analysis of the cleavage sites suggests that DNA topology rather than a particular sequence determines the cleavage site. RuvC protein also cleaves Holliday junctions that are formed between gapped circular and linear duplex DNA by the function of RecA protein. The active form of RuvC protein is a dimer. This is mechanistically suited for an endonuclease involved in swapping DNA strands at the crossover junctions. It is inferred that RuvC protein is an endonuclease that resolves Holliday structures in vivo[]. RucC is a small protein of about 20 kD. It requires and binds a magnesium ion. The structure of E. coli ruvC is a 3-layer alpha-beta sandwich containing a 5-stranded beta-sheet sandwiched between 5 alpha-helices [].This signature pattern covers a region located in the C-terminal part of RuvC that contains two aspartate residues implicated in the binding of a magnesium ion required for function. | Short Name: | X-over_junc_endoDNase_Mg_BS |
