Fluorescent Biosensor for Detection of the R248Q Aggregation‐Prone Mutant of p53

The p53 tumour suppressor and guardian of the genome undergoes missense mutations that lead to functional inactivation in 50 % of human cancers. These mutations occur mostly in the DNA‐binding domain of the protein, and several of these result in conformational changes that lead to amyloid‐like protein aggregation. Herein, we describe a fluorescent biosensor that reports on the R248Q mutant of p53 in vitro and in living cells, engineered through conjugation of an environmentally sensitive probe onto a peptide derived from the primary aggregation segment of p53. This biosensor was characterised both in vitro and by means of fluorescence microscopy following facilitated delivery into cultured cells. It is shown that this biosensor preferentially reports on the p53 R248Q mutant in the PC9 lung cancer cell line compared with other lung cancer cell lines harbouring either wild‐type or no p53. Reporting abnormalities: A p53 peptide biosensor that preferentially reports on the R248Q mutant in vitro and in living cells is reported. This biosensor has been engineered through conjugation of a peptide derived from the main aggregation‐nucleating motif of p53 to the solvatochromic TP2‐Rho probe.