E. Coli. G-Quadruplexes: Do They Act As Chaperones?

Nucleic acids play versatile roles in the cell. Recently, it has been reported that nucleic acids also have a role in preventing protein aggregation and assisting protein folding and even have more potent activity than traditional chaperones. With these findings, we also showed that the chaperoning function of nucleic acids is sequence-specific, and especially a poly G motif, forming G-quadruplexes, has strong holdase activity. Although the function of G-quadruplexes remains largely unknown, it has been reported that both eukaryotic and prokaryotic cells have endogenous G-quadruplexes. Thus, the goal of this study is to determine whether endogenous G-quadruplexes in E. coli have chaperone activity by using fluorescence protein TagRFP675 as a folding biosensor. We obtained an RNA library which expresses known endogenous G-quadruplex sequences of E. coli, transformed it into our test strains and performed cell sorting to screen the best chaperone sequences in cells, and we further investigated that the sorted RNA library enhances fluorescence of TagRFP675. We will further use thermal aggregation plate reader assay to test top hits for efficacy as chaperones. This research plays a pivotal role in elucidating veiled function of G-quadruplexes and would provide a key to solve protein aggregation-associated diseases such as ALS and Alzheimer’s Disease.