RuvB

RuvB is a bacterial DNA recombination factor that functions as an ATP-driven motor protein in the Holliday junction processing pathway. It is a member of the AAA+ family of ATPases and works together with RuvA and RuvC to promote homologous recombination and DNA repair in many bacteria, notably Escherichia coli.

In the Holliday junction repair process, RuvA binds the junction DNA as a tetramer, creating a platform for RuvB. RuvB forms hexameric rings that associate with the RuvA–DNA complex to create the RuvAB complex. This motor uses energy from ATP hydrolysis to translocate DNA on opposite sides of the junction, driving branch migration. The migrating junction is then resolved by RuvC, an endonuclease that cleaves the DNA at the appropriate points to separate the recombined chromosomes.

Structurally, RuvB is an ATPase that assembles into hexamers and contains conserved Walker A and Walker B motifs necessary for ATP binding and hydrolysis. The exact arrangement places RuvB rings adjacent to the junction, enabling coordinated movement of the DNA while RuvA stabilizes the junction structure.

RuvB-like activity is not limited to bacteria. Eukaryotes possess homologs, notably RUVBL1 and RUVBL2 (also known as Pontin and Reptin), which are AAA+ ATPases involved in chromatin remodeling and various nuclear processes. In eukaryotic cells, these proteins participate in complexes such as INO80 and SWR1 and contribute to transcription regulation and the DNA damage response.

Overall, RuvB is essential for efficient processing of recombination intermediates in bacteria and has conserved relatives in eukaryotes that participate in broader chromatin-related functions.