A novel G-quadruplex motif modulates promoter activity of human thymidine kinase 1.
G-quadruplex motifs constitute unusual DNA secondary structures formed by stacking of planar hydrogen-bonded G-tetrads. Recent genome-wide bioinformatics and experimental analyses have suggested the interesting possibility that G-quadruplex motifs could be cis-regulatory elements. Here, we identified a characteristic potential G-quadruplex-forming sequence element within the promoter of human thymidine kinase 1 (TK1). Our NMR, UV and CD spectroscopy and gel electrophoresis data suggested that this sequence forms a novel intramolecular G-quadruplex with two G-tetrads in K(+) solution. The results presented here indicate the role of this G-quadruplex motif in transcription of TK1 in cell-based reporter assays. Specific nucleotide substitutions designed to destabilize the G-quadruplex motif resulted in increased promoter activity, supporting direct involvement of the G-quadruplex motif in transcription of TK1. These studies suggest that the G-quadruplex motif may be an important target for controlling critical biological processes, such as DNA synthesis, mediated by TK1.
Basundra
Richa
R
Proteomics and Structural Biology Unit, Institute of Genomics and Integrative Biology, CSIR, Delhi, India.
Kumar
Akinchan
A
Amrane
Samir
S
Verma
Anjali
A
Phan
Anh Tuân
AT
Chowdhury
Shantanu
S
D054856:G-Quadruplexes; D006801:Humans; D009690:Nucleic Acid Conformation; D011188:Potassium; D011401:Promoter Regions, Genetic; D012045:Regulatory Sequences, Nucleic Acid; D012996:Solutions; D013057:Spectrum Analysis; D013937:Thymidine Kinase / Q000235:genetics*; D014158:Transcription, Genetic
D012996:Solutions; D013937:Thymidine Kinase; C092717:thymidine kinase 1; D011188:Potassium