Human replication protein A unfolds telomeric G-quadruplexes.

Tonatiuh Romero Salas (1) , Irina Petruseva (2) , Olga Lavrik (2) , Anne Bourdoncle (3) , Jean-Louis Mergny (3) , Alain Favre (1) , Carole Saintomé (1)

1 IJM (UMR_7592) - Institut Jacques Monod
2 Novosibirsk Institute of Bioorganic Chemistr
3 ANDCFB - Acides nucléiques : dynamique, ciblage, et fonctions biologiques - Régulation et dynamique des génomes

G-quadruplex structures inhibit telomerase activity and must be disrupted for telomere elongation during S phase. It has been suggested that the replication protein A (RPA) could unwind and maintain single-stranded DNA in a state amenable to the binding of telomeric components. We show here that under near-physiological in vitro conditions, human RPA is able to bind and unfold G-quadruplex structures formed from a 21mer human telomeric sequence. Analyses by native gel electrophoresis, cross-linking and fluorescence resonance energy transfer indicate the formation of both 1:1 and 2:1 complexes in which G-quadruplexes are unfolded. In addition, quadruplex opening by hRPA is much faster than observed with the complementary DNA, demonstrating that this protein efficiently unfolds G-quartets. A two-step mechanism accounting for the binding of hRPA to G-quadruplexes is proposed. These data point to the involvement of hRPA in regulation of telomere maintenance.

Domaines: Biologie moléculaire

Tonatiuh Romero Salas, Irina Petruseva, Olga Lavrik, Anne Bourdoncle, Jean-Louis Mergny, et al.. Human replication protein A unfolds telomeric G-quadruplexes.. Nucleic Acids Research, 2006, 34 (17), pp.4857-65. ⟨10.1093/nar/gkl564⟩. ⟨hal-00097468⟩