title: Single-Molecule Analysis of Human Telomere Sequence Interactions with G-quadruplex Ligand.
abstract: Ligands that selectively promote the formation of G-quadruplexes in human telomeres have great potential for cancer treatment by inhibiting the telomere extension by telomerase. Thus, understanding the interactions of the G-quadruplex ligands with the telomere sequence at the single-molecule level is of significant importance. Here, human telomere sequence interactions with a small molecule ligand pyridostatin (PDS) were analyzed via α-hemolysin protein nanopore, and a nanopore thermodynamic analytical method was proposed. The prolonged unraveling time of the telomeric DNA G-quadruplex after PDS binding demonstrated the potent stabilization effect of ligand on G-quadruplex structure. The signature two-level electronic blocks generated by K(+)-PDS-G-quadruplex complexes suggested a two-state unraveling process, including the dissociation of the interquartet cation and the unraveling of the cation-free ligand-bound G-quadruplex. The translocation studies and the analysis of free-energy changes demonstrated a ligand-binding mode in which PDS molecule and K(+) were simultaneously bound to one G-quadruplex structure with the coordinated effect on G-quadruplex stabilization. The single-molecular nanopore platform permits the efficient and accurate determination of ligand affinity constants without the requirement for labeling, amplification, or ligand/receptor titration, which provides a general analytical tool for effectively monitoring and quantifying the G-quadruplex/ligand interactions, possessing important implications for the design and screen of anticancer drugs.
authors.affiliation: Department of Chemistry, Beijing Key Laboratory for Analytical Methods and Instrumentation, Tsinghua University , Beijing 100084, China.
authors.forename: Ling
authors.initials: L
authors.lastname: Zhang
authors.affiliation: Department of Chemistry, Beijing Key Laboratory for Analytical Methods and Instrumentation, Tsinghua University , Beijing 100084, China.
authors.forename: Kaixiang
authors.initials: K
authors.lastname: Zhang
authors.affiliation: Department of Chemistry, Beijing Key Laboratory for Analytical Methods and Instrumentation, Tsinghua University , Beijing 100084, China.
authors.forename: Sana
authors.initials: S
authors.lastname: Rauf
authors.affiliation: Department of Chemistry, Beijing Key Laboratory for Analytical Methods and Instrumentation, Tsinghua University , Beijing 100084, China.
authors.forename: Duo
authors.initials: D
authors.lastname: Dong
authors.affiliation: Department of Chemistry, Beijing Key Laboratory for Analytical Methods and Instrumentation, Tsinghua University , Beijing 100084, China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Department of Chemistry, Beijing Key Laboratory for Analytical Methods and Instrumentation, Tsinghua University , Beijing 100084, China.
authors.forename: Jinghong
authors.initials: J
authors.lastname: Li
mesh_terms: D000634:Aminoquinolines / Q000737:chemistry*; D001483:Base Sequence; D054856:G-Quadruplexes; D006460:Hemolysin Proteins / Q000737:chemistry*; D006801:Humans; D008024:Ligands; D058608:Nanopores; D010848:Picolinic Acids / Q000737:chemistry*; D011188:Potassium / Q000737:chemistry; D000072760:Single Molecule Imaging; D016615:Telomere / Q000737:chemistry*; D013816:Thermodynamics
chemical_list: D000634:Aminoquinolines; D006460:Hemolysin Proteins; D008024:Ligands; D010848:Picolinic Acids; C567962:pyridostatin; D011188:Potassium