Bacterial RadA is a DnaB-type helicase interacting with RecA to promote bidirectional D-loop extension.

TitleBacterial RadA is a DnaB-type helicase interacting with RecA to promote bidirectional D-loop extension.
Publication TypeJournal Article
Year of Publication2017
AuthorsMarie, L., C. Rapisarda, V. Morales, M. Bergé, T. Perry, A-L. Soulet, C. Gruget, H. Remaut, R. Fronzes, and P. Polard
JournalNat Commun
Volume8
Pagination15638
Date Published2017 May 31
ISSN2041-1723
Abstract

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.

DOI10.1038/ncomms15638
Alternate JournalNat Commun
PubMed ID28561029
PubMed Central IDPMC5512693
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