Nanometer Distance Measurements between Multicolor Quantum Dots

Quantum dot dimers made of short double-stranded DNA molecules labeled with different color quantum dots at each end were imaged using multicolor stage-scanning confocal microscopy. This approach eliminates chromatic aberration and color registration issues usually encountered in other multicolor imaging techniques. We demonstrate nanometer accuracy in individual distance measurement by suppression of quantum dot blinking and thoroughly characterize the contribution of different effects to the variability observed between measurements. Our analysis opens the way to accurate structural studies of biomolecules and biomolecular complexes using multicolor quantum labeling

Lighting Up Individual DNA Binding Proteins with Quantum Dots

The ability to determine the precise loci and occupancy of DNA-binding proteins is instrumental to our understanding of cellular processes like gene expression and regulation. We propose a single-molecule approach for the direct visualization of proteins bound to their template DNA. Fluorescent quantum dots (QD) are used to label proteins bound to DNA, allowing multicolor, nanometer-resolution localization. Protein−DNA complexes are linearly extended and imaged to determine the precise location of the protein binding sites. The method is demonstrated by detecting individual QD-labeled T7-RNA polymerases on the T7 bacteriophage genome. This work demonstrates the potential of this approach to precisely read protein binding position or, alternatively, “write” such information on extended DNA with QDs via sequence-specific molecular recognition

Lighting Up Individual DNA Binding Proteins with Quantum Dots

The ability to determine the precise loci and occupancy of DNA-binding proteins is instrumental to our understanding of cellular processes like gene expression and regulation. We propose a single-molecule approach for the direct visualization of proteins bound to their template DNA. Fluorescent quantum dots (QD) are used to label proteins bound to DNA, allowing multicolor, nanometer-resolution localization. Protein−DNA complexes are linearly extended and imaged to determine the precise location of the protein binding sites. The method is demonstrated by detecting individual QD-labeled T7-RNA polymerases on the T7 bacteriophage genome. This work demonstrates the potential of this approach to precisely read protein binding position or, alternatively, “write” such information on extended DNA with QDs via sequence-specific molecular recognition