Identification of the DNA-Binding Domains of Human Replication Protein A That Recognize G-Quadruplex DNA

Abstract EN

Replication protein A (RPA), a key player in DNA metabolism, has 6 single-stranded DNA-(ssDNA-) binding domains (DBDs) A-F.

SELEX experiments with the DBDs-C, -D, and -E retrieve a 20-nt G-quadruplex forming sequence.

Binding studies show that RPA-DE binds preferentially to the G-quadruplex DNA, a unique preference not observed with other RPA constructs.

Circular dichroism experiments show that RPA-CDE-core can unfold the G-quadruplex while RPA-DE stabilizes it.

Binding studies show that RPA-C binds pyrimidine- and purine-rich sequences similarly.

This difference between RPA-C and RPA-DE binding was also indicated by the inability of RPA-CDE-core to unfold an oligonucleotide containing a TC-region 5′ to the G-quadruplex.

Molecular modeling studies of RPA-DE and telomere-binding proteins Pot1 and Stn1 reveal structural similarities between the proteins and illuminate potential DNA-binding sites for RPA-DE and Stn1.

These data indicate that DBDs of RPA have different ssDNA recognition properties.