TY - JOUR
T1 - Stabilization of a G-quadruplex from unfolding by replication protein A using potassium and the porphyrin TMPyP4
AU - Prakash, Aishwarya
AU - Kieken, Fabien
AU - Marky, Luis A.
AU - Borgstahl, Gloria E.O.
PY - 2011
Y1 - 2011
N2 - Replication protein A (RPA) plays an essential role in DNA replication by binding and unfolding non-canonical single-stranded DNA (ssDNA) structures. Of the six RPA ssDNA binding domains (labeled A-F), RPA-CDE selectively binds a G-quadruplex forming sequence (5′ -TAGGGGAAGGGTTGGAGTGGGTT- 3′ called Gq23). In K+, Gq23 forms a mixed parallel/antiparallel conformation, and in Na+ Gq23 has a less stable (T M lowered by ∼ 20 ° C), antiparallel conformation. Gq23 is intramolecular and 1D NMR confirms a stable G-quadruplex structure in K+. Full-length RPA and RPA-CDE-core can bind and unfold the Na+ form of Gq23 very efficiently, but complete unfolding is not observed with the K+ form. Studies with G-quadruplex ligands, indicate that TMPyP4 has a thermal stabilization effect on Gq23 in K+, and inhibits complete unfolding by RPA and RPA-CDE-core. Overall these data indicate that G-quadruplexes present a unique problem for RPA to unfold and ligands, such as TMPyP4, could possibly hinder DNA replication by blocking unfolding by RPA.
AB - Replication protein A (RPA) plays an essential role in DNA replication by binding and unfolding non-canonical single-stranded DNA (ssDNA) structures. Of the six RPA ssDNA binding domains (labeled A-F), RPA-CDE selectively binds a G-quadruplex forming sequence (5′ -TAGGGGAAGGGTTGGAGTGGGTT- 3′ called Gq23). In K+, Gq23 forms a mixed parallel/antiparallel conformation, and in Na+ Gq23 has a less stable (T M lowered by ∼ 20 ° C), antiparallel conformation. Gq23 is intramolecular and 1D NMR confirms a stable G-quadruplex structure in K+. Full-length RPA and RPA-CDE-core can bind and unfold the Na+ form of Gq23 very efficiently, but complete unfolding is not observed with the K+ form. Studies with G-quadruplex ligands, indicate that TMPyP4 has a thermal stabilization effect on Gq23 in K+, and inhibits complete unfolding by RPA and RPA-CDE-core. Overall these data indicate that G-quadruplexes present a unique problem for RPA to unfold and ligands, such as TMPyP4, could possibly hinder DNA replication by blocking unfolding by RPA.
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U2 - 10.4061/2011/529828
DO - 10.4061/2011/529828
M3 - Article
C2 - 21772995
AN - SCOPUS:84862089289
SN - 2090-0201
VL - 2011
JO - Journal of Nucleic Acids
JF - Journal of Nucleic Acids
M1 - 529828
ER -