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A Key Presynaptic Role in Transformation for a Widespread Bacterial Protein: DprA Conveys Incoming ssDNA to RecA

2007; Cell Press; Volume: 130; Issue: 5 Linguagem: Inglês

10.1016/j.cell.2007.07.038

1097-4172

Isabelle Mortier‐Barrière, Marion Velten, P. Dupaigne, Nicolas Mirouze, Olivier Piétrement, Stephen McGovern, Gwennaële Fichant, Bernard Martin, Philippe Noirot, Éric Le Cam, Patrice Polard, Jean‐Pierre Claverys,

Bacteriophages and microbial interactions

Summary Natural transformation is a mechanism for genetic exchange in many bacterial genera. It proceeds through the uptake of exogenous DNA and subsequent homology-dependent integration into the genome. In Streptococcus pneumoniae , this integration requires the ubiquitous recombinase, RecA, and DprA, a protein of unknown function widely conserved in bacteria. To unravel the role of DprA, we have studied the properties of the purified S. pneumoniae protein and its Bacillus subtilis ortholog (Smf). We report that DprA and Smf bind cooperatively to single-stranded DNA (ssDNA) and that these proteins both self-interact and interact with RecA. We demonstrate that DprA-RecA-ssDNA filaments are produced and that these filaments catalyze the homology-dependent formation of joint molecules. Finally, we show that while the Escherichia coli ssDNA-binding protein SSB limits access of RecA to ssDNA, DprA lowers this barrier. We propose that DprA is a new member of the recombination-mediator protein family, dedicated to natural bacterial transformation.