A Rhodium-Cyanine Fluorescent Probe: Detection and Signaling of Mismatches in DNA

Abstract

<p class="first" id="P1">We report a bifunctional fluorescent probe that combines a rhodium metalloinsertor with a cyanine dye as the fluorescent reporter. The conjugate shows weak luminescence when free in solution or with well matched DNA but exhibits a significant luminescence increase in the presence of a 27-mer DNA duplex containing a central CC mismatch. DNA photocleavage experiments demonstrate that, upon photoactivation, the conjugate cleaves the DNA backbone specifically near the mismatch site on a 27-mer fragment, consistent with mismatch targeting. Fluorescence titrations with the 27-mer duplex containing the CC mismatch reveal a DNA binding affinity of 3.1 × 10 ⁶ M ⁻¹, similar to that of other rhodium metalloinsertors. Fluorescence titrations using genomic DNA extracted from various cell lines demonstrate a clear discrimination in fluorescence between those cell lines that are proficient or deficient in mismatch repair. This differential luminescence reflects the sensitive detection of the mismatch repair-deficient phenotype. </p><p id="P2"> <div class="figure-container so-text-align-c"> <img alt="" class="figure" src="/document_file/6e1c998a-3f91-4209-9156-313eedae896e/PubMedCentral/image/nihms942611u1.jpg"/> </div> </p>