A highly sensitive and rapid method for the detection of DNA fragments using the photoprotein obelin as a reporter

The recombinant Ca²⁺-activated photoprotein obelin was used as a reporter protein in a solid-phase bioluminescent hybridization DNA assay. Oligonucleotide probes were immobilized on the surface of polymer methacrylate beads or microbiological plates of different types. A 30-mer oligonucleotide or its derivative with the biotin residue on the 3′-terminus, as well as a denatured double-stranded PCR fragment of the hepatitis C virus with the sequence of the 30-mer oligonucleotide was used as a DNA template. The probe in the hybridization complex was labeled by the elongation of the chain using a Taq DNA polymerase in the presence of biotinylated deoxyuridine triphosphate. The results of the bioluminescent assay were compared with the results of colorimetric analysis obtained with alkaline phosphatase as a reporter protein. It was shown that the use of the bioluminescent obelin label substantially accelerates the DNA detection procedure, provides a high sensitivity of the assay (no less than 10^?15 mol of DNA template), and ensures a quantitative determination of the amount of DNA template in the tested sample.