Optical sequence probing with the homologous recombination protein RecA

Area of Science:

• Molecular Biology
• Biophysics
• Nanotechnology

Background:

• Accurate DNA sequence detection is crucial for molecular diagnostics and research.
• Traditional methods can be complex and time-consuming.
• Developing novel, efficient methods for DNA sequence identification is an ongoing challenge.

Purpose of the Study:

• To investigate the use of the homologous recombination protein RecA for locating specific DNA sequences.
• To develop a method for optical detection of DNA sequences using RecA-mediated binding.
• To demonstrate the feasibility of using fluorescently labeled DNA probes with RecA for sequence identification.

Main Methods:

• Synthesized and labeled an 80-mer single-stranded (ss) DNA probe with quantum dots (Qdots) via biotin-avidin linkage.
• Formed a fluorescent ssDNA-RecA complex by incubating the labeled ssDNA with RecA protein.
• Immobilized target lambda (λ) DNA onto microelectrodes using an electrostatic method.
• Incubated the target DNA with the fluorescent ssDNA-RecA complex and observed binding using fluorescence microscopy.

Main Results:

• Clear fluorescence spots were observed on individual target DNA molecules where the ssDNA-RecA complex bound.
• The binding positions were analyzed using histograms, revealing a distinct peak.
• This peak corresponded to the location complementary to the probe ssDNA sequence on the target DNA.
• Demonstrated successful RecA-facilitated localization of a specific DNA sequence.

Conclusions:

• The homologous recombination protein RecA can facilitate the optical detection and localization of specific DNA sequences.
• This method offers a novel approach for sequence-specific DNA detection with potential applications in diagnostics and research.
• Quantum dot-labeled DNA probes combined with RecA show promise for high-sensitivity DNA sequence identification.