Telomeric G-quadruplexes are a substrate and site of localization for human telomerase

• Published in: Nature communications Vol. 6; no. 1; p. 7643
• Main Authors: Moye, Aaron L., Porter, Karina C., Cohen, Scott B., Phan, Tram, Zyner, Katherine G., Sasaki, Natsuki, Lovrecz, George O., Beck, Jennifer L., Bryan, Tracy M.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 09-07-2015; Nature Publishing Group; Nature Pub. Group
• Subjects: 101/58; 13; 13/1; 14; 14/32; 14/63; 631/337/103/560; 631/45/535; 631/45/612/1230; 82; 82/29; 82/80; 82/83; 96; Blotting, Western; Circular Dichroism; DNA - metabolism; Electrophoresis, Polyacrylamide Gel; G-Quadruplexes - drug effects; HEK293 Cells; Humanities and Social Sciences; Humans; In Situ Hybridization, Fluorescence; Mesoporphyrins - pharmacology; multidisciplinary; Science; Science (multidisciplinary); Spectrometry, Mass, Electrospray Ionization; Telomerase - metabolism; Telomere Homeostasis
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/ncomms8643

It has been hypothesized that G-quadruplexes can sequester the 3′ end of the telomere and prevent it from being extended by telomerase. Here we purify and characterize stable, conformationally homogenous human telomeric G-quadruplexes, and demonstrate that human telomerase is able to extend parallel, intermolecular conformations
in vitro
. These G-quadruplexes align correctly with the RNA template of telomerase, demonstrating that at least partial G-quadruplex resolution is required. A highly purified preparation of human telomerase retains this extension ability, establishing that the core telomerase enzyme complex is sufficient for partial G-quadruplex resolution and extension. The parallel-specific G-quadruplex ligand
N
-methyl mesoporphyrin IX (NMM) causes an increase in telomeric G-quadruplexes, and we show that telomerase colocalizes with a subset of telomeric G-quadruplexes
in vivo
. The ability of telomerase to partially unwind, extend and localize to these structures implies that parallel telomeric G-quadruplexes may play an important biological role.
G-quadruplexes formed by four guanine bases in a square planar arrangement in telomeres may prevent extension of this region by telomerase. Here, the authors show that telomerase can localize to and partially unwind and extend G-quadruplexes, suggesting an important biological role for G-quadruplexes.