Fidelity of DNA recombination catalyzed by human Dmc1 recombinase

BORGOGNO MARÍA V; PEZZA ROBERTO J; ARGARAÑA CARLOS E; MONTI MARIELA R

Rosario, Santa Fé

Congreso; L Reunión Anual de SAIB; 2014

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

Dmc1 is a meiosis-specific recombinase that carries out the search for DNA homology and catalyzes the strand exchange (StEx) reaction during homologous recombination (HR). Previous works have suggested that heterologies in DNA affect the StEx reaction catalyzed by recombinases and therefore the fidelity of HR. To study the influence of heterologies on HR promoted by human Dmc1, we analyzed the efficiency of StEx using oligonucleotides containing different types, frequency and distribution of mismatches (MM). We examined by fluorescence resonance energy transfer the StEx reaction of 12 different types of single-MM in three positions of the incoming oligonucleotide strand. We found that some types of MM had a stronger inhibitory effect on StEx when they werenear the 5? end of the incoming strand. This effect was not observed in the middle or 3? end position. A similar trend was obtained when the frequency of MM was increased. In addition, we examined if the presence of Hop2-Mnd1complex, which interacts with Dmc1 and enhances HR, affects the discrimination of DNA heterologies. We observed that Hop2-Mnd1 only stimulated Dmc1-StEx reaction in the presence of a single MM. Finally, analysis of differentmutants of Hop2 and Mnd1 revealed that Mnd1 DNA binding site is important to stimulate Dmc1. Thus, our data provide new insights on the fidelity of HR catalyzed by human Dmc1.