Structure-function analysis of pneumococcal DprA protein reveals that dimerization is crucial for loading RecA recombinase onto DNA during transformation

Sophie S. Quevillon-Cheruel (1) , Nathalie N. Campo (2) , Nicolas N. Mirouze (3) , Isabelle I. Mortier (2) , Mark A. M. A. Brooks (1) , Marion M. Boudes (1) , Dominique D. Durand (1) , Anne-Lise A.-L. Soulet (2) , Johnny J. Lisboa (1) , Philippe P. Noirot (3) , Bernard B. Martin (2) , Herman H. van Tilbeurgh (1) , Marie Francoise M. F. Noirot-Gros (3) , Jean-Pierre J.-P. Claverys (2) , Patrice P. Polard (2)

1 Ctr Natl Rech Sci, Inst Biochim & Biophys Mol & Cellulaire, Unite Mixte Rech 8619
2 LMGM - Laboratoire de microbiologie et génétique moléculaires - UMR5100
3 MICALIS - MICrobiologie de l'ALImentation au Service de la Santé

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.

Mots clés: CRYSTAL-STRUCTURE; GENETIC-TRANSFORMATION; STREPTOCOCCUS-PNEUMONIAE; horizontal gene transfer; recombination mediator protein; recombinase loader; genetic exchange; bacterial transformation; BACTERIAL PROTEIN; RECBCD ENZYME; COMPETENCE; BINDING; DOMAIN; IDENTIFICATION; COMPLEX

Domaines: Sciences agricoles

Sophie S. Quevillon-Cheruel, Nathalie N. Campo, Nicolas N. Mirouze, Isabelle I. Mortier, Mark A. M. A. Brooks, et al.. Structure-function analysis of pneumococcal DprA protein reveals that dimerization is crucial for loading RecA recombinase onto DNA during transformation. Proceedings of the National Academy of Sciences of the United States of America, 2012, 109 (37), pp.E2466 - E2475. ⟨10.1073/pnas.1205638109⟩. ⟨hal-01004530⟩