Identification\nof SLIRP as a G Quadruplex-Binding\nProtein

Abstract

The guanine quadruplex (G4) structure\nin DNA is a secondary structure\nmotif that plays important roles in DNA replication, transcriptional\nregulation, and maintenance of genomic stability. Here, we employed\na quantitative mass spectrometry-based approach to profile the interaction\nproteomes of three well-defined G4 structures derived from the human\ntelomere and the promoters of <i>cMYC</i> and <i>cKIT</i> genes. We identified SLIRP as a novel G4-interacting protein. We\nalso demonstrated that the protein could bind directly with G4 DNA\nwith <i>K</i>_d values in the low nanomolar range\nand revealed that the robust binding of the protein toward G4 DNA\nrequires its RRM domain. We further assessed, by using CRISPR-Cas9-introduced\naffinity tag and ChIP-Seq analysis, the genome-wide occupancy of SLIRP,\nand showed that the protein binds preferentially to G-rich DNA sequences\nthat can fold into G4 structures. Together, our results uncovered\na novel cellular protein that can interact directly with G4 DNA, which\nunderscored the complex regulatory networks involved in G4 biology.