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Publication Abstract from PubMed

Transformation promotes genome plasticity in bacteria via RecA-driven homologous recombination. In the Gram-positive human pathogen Streptococcus pneumoniae, the transformasome a multiprotein complex, internalizes, protects, and processes transforming DNA to generate chromosomal recombinants. Double-stranded DNA is internalized as single strands, onto which the transformation-dedicated DNA processing protein A (DprA) ensures the loading of RecA to form presynaptic filaments. We report that the structure of DprA consists of the association of a sterile alpha motif domain and a Rossmann fold and that DprA forms tail-to-tail dimers. The isolation of DprA self-interaction mutants revealed that dimerization is crucial for the formation of nucleocomplexes in vitro and for genetic transformation. Residues important for DprA-RecA interaction also were identified and mutated, establishing this interaction as equally important for transformation. Positioning of key interaction residues on the DprA structure revealed an overlap of DprA-DprA and DprA-RecA interaction surfaces. We propose a model in which RecA interaction promotes rearrangement or disruption of the DprA dimer, enabling the subsequent nucleation of RecA and its polymerization onto ssDNA.

Structure-function analysis of pneumococcal DprA protein reveals that dimerization is crucial for loading RecA recombinase onto DNA during transformation.,Quevillon-Cheruel S, Campo N, Mirouze N, Mortier-Barriere I, Brooks MA, Boudes M, Durand D, Soulet AL, Lisboa J, Noirot P, Martin B, van Tilbeurgh H, Noirot-Gros MF, Claverys JP, Polard P Proc Natl Acad Sci U S A. 2012 Aug 17. PMID:22904190^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.