Engineering yellow fluorescent protein probe for visualization of parallel DNA G-quadruplex

The formation of G-quadruplex plays a key role in many biological processes. Therefore, visualization of G-quadruplex is highly essential for design of G-quadruplex-targeted small molecules (drugs). Herein, we report on an engineered fluorescent protein probe which was able to distinguish G-quadruplex topologies. Methods: The fluorescent protein probe was generated by genetically incorporating yellow fluorescent protein (YFP) to RNA helicase associated with AU-rich element (RHAU) peptide motif. Results: This probe could selectively bind and visualize parallel G-quadruplex structure (T95-2T) at high affinity (Kd~130 nM). Visualization of the parallel G-quadruplex by RHAU-YFP could be easily observed in vitro by using normal Gel Doc or the naked eye. Conclusion: The YFP probe could be encoded in cells to provide a powerful tool for detection of parallel G-quadruplexes both in vitro and in vivo.