Solution structure of all parallel G-quadruplex formed by the oncogene RET promoter sequence
Tong, X., Lan, W., Zhang, X., Wu, H., Liu, M., Cao, C.(2011) Nucleic Acids Res 39: 6753-6763
- PubMed: 21540209 
- DOI: https://doi.org/10.1093/nar/gkr233
- Primary Citation of Related Structures:  
2L88 - PubMed Abstract: 
RET protein functions as a receptor-type tyrosine kinase and has been found to be aberrantly expressed in a wide range of human diseases. A highly GC-rich region upstream of the promoter plays an important role in the transcriptional regulation of RET. Here, we report the NMR solution structure of the major intramolecular G-quadruplex formed on the G-rich strand of this region in K(+) solution. The overall G-quadruplex is composed of three stacked G-tetrad and four syn guanines, which shows distinct features for all parallel-stranded folding topology. The core structure contains one G-tetrad with all syn guanines and two other with all anti-guanines. There are three double-chain reversal loops: the first and the third loops are made of 3 nt G-C-G segments, while the second one contains only 1 nt C10. These loops interact with the core G-tetrads in a specific way that defines and stabilizes the overall G-quadruplex structure and their conformations are in accord with the experimental mutations. The distinct RET promoter G-quadruplex structure suggests that it can be specifically involved in gene regulation and can be an attractive target for pathway-specific drug design.
Organizational Affiliation: 
State Key Laboratory of Bio-organic and Natural Products Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, 200032, China. tongxt@mail.sioc.ac.cn