RuvAB

RuvAB is a bacterial protein complex that plays a crucial role in homologous recombination and DNA repair processes. The complex consists of two proteins: RuvA and RuvB, which work together to facilitate branch migration of Holliday junctions during genetic recombination.

The RuvA protein serves as the recognition and binding component of the complex. It specifically binds to Holliday junctions, which are four-stranded DNA structures that form during homologous recombination. RuvA stabilizes these junctions and prepares them for further processing. The protein contains domains that allow it to recognize and interact with the branched DNA structure, positioning it for subsequent branch migration.

RuvB functions as the motor component of the complex, providing the ATP-dependent helicase activity necessary for branch migration. It forms a hexameric ring structure that encircles the DNA, using energy from ATP hydrolysis to drive the movement of the Holliday junction. This process, known as branch migration, involves the coordinated movement of the crossover point along the DNA helix, allowing for efficient resolution of recombination intermediates.

The RuvAB complex is essential for bacterial survival under conditions that induce DNA damage. It is particularly important for repairing double-strand breaks and maintaining genome stability. Mutations in either RuvA or RuvB result in increased sensitivity to DNA-damaging agents and reduced viability.

The system is well-conserved across bacterial species, with homologs found in many different bacterial lineages. Studies of RuvAB have provided significant insights into the mechanisms of homologous recombination and have contributed to our understanding of how cells maintain genomic integrity. The complex represents an elegant example of how specialized protein machines coordinate to resolve complex DNA structures during essential cellular processes.