Abraham Punnoose Jibin, Ma Yue, Hoque Mohammed Enamul, Cui Yunxi, Sasaki Shogo, Guo Athena Huixin, Nagasawa Kazuo, Mao Hanbin
Department of Chemistry and Biochemistry , Kent State University , Kent , Ohio 44242 , United States.
Department of Biotechnology and Life Science Faculty of Technology , Tokyo University of Agriculture and Technology (TUAT) , 2-14-16 Naka-cho , Koganeishi, Tokyo 184-8588 , Japan.
Biochemistry. 2018 Dec 26;57(51):6946-6955. doi: 10.1021/acs.biochem.8b00957. Epub 2018 Dec 11.
G-Quadruplexes formed in the 3' telomere overhang (∼200 nucleotides) have been shown to regulate biological functions of human telomeres. The mechanism governing the population pattern of multiple telomeric G-quadruplexes is yet to be elucidated inside the telomeric overhang in a time window shorter than thermodynamic equilibrium. Using a single-molecule force ramping assay, we quantified G-quadruplex populations in telomere overhangs over a full physiological range of 99-291 nucleotides. We found that G-quadruplexes randomly form in these overhangs within seconds, which leads to a population governed by a kinetic, rather than a thermodynamic, folding pattern. The kinetic folding gives rise to vacant G-tracts between G-quadruplexes. By targeting these vacant G-tracts using complementary DNA fragments, we demonstrated that binding to the telomeric G-quadruplexes becomes more efficient and specific for telomestatin derivatives.
已证明在3'端粒悬垂（约200个核苷酸）中形成的G-四链体可调节人类端粒的生物学功能。在比热力学平衡更短的时间窗口内，端粒悬垂内部控制多个端粒G-四链体群体模式的机制尚待阐明。使用单分子力递增测定法，我们在99-291个核苷酸的完整生理范围内对端粒悬垂中的G-四链体群体进行了定量。我们发现G-四链体在几秒钟内在这些悬垂中随机形成，这导致群体受动力学而非热力学折叠模式支配。动力学折叠在G-四链体之间产生空的G序列。通过使用互补DNA片段靶向这些空的G序列，我们证明与端粒G-四链体的结合对端粒抑素衍生物变得更有效且更具特异性。
