|Title||Bacterial RadA is a DnaB-type helicase interacting with RecA to promote bidirectional D-loop extension.|
|Publication Type||Journal Article|
|Year of Publication||2017|
|Authors||Marie, L., C. Rapisarda, V. Morales, M. Bergé, T. Perry, A-L. Soulet, C. Gruget, H. Remaut, R. Fronzes, and P. Polard|
|Date Published||2017 May 31|
Homologous recombination (HR) is a central process of genome biology driven by a conserved recombinase, which catalyses the pairing of single-stranded DNA (ssDNA) with double-stranded DNA to generate a D-loop intermediate. Bacterial RadA is a conserved HR effector acting with RecA recombinase to promote ssDNA integration. The mechanism of this RadA-mediated assistance to RecA is unknown. Here, we report functional and structural analyses of RadA from the human pathogen Streptococcus pneumoniae. RadA is found to facilitate RecA-driven ssDNA recombination over long genomic distances during natural transformation. RadA is revealed as a hexameric DnaB-type helicase, which interacts with RecA to promote orientated unwinding of branched DNA molecules mimicking D-loop boundaries. These findings support a model of DNA branch migration in HR, relying on RecA-mediated loading of RadA hexamers on each strand of the recipient dsDNA in the D-loop, from which they migrate divergently to facilitate incorporation of invading ssDNA.
|Alternate Journal||Nat Commun|
|PubMed Central ID||PMC5512693|
Bacterial RadA is a DnaB-type helicase interacting with RecA to promote bidirectional D-loop extension.