Figure 2
Single molecule detection of a low abundance protein. (A) HaloTag-HTL-TMR allows single molecule detection. After in vivo labelling cells were chemically fixed to stop protein diffusion. A strain containing a RecB-HaloTag fusion showed diffraction limited spots corresponding to single RecB molecules when incubated with HTL-TMR (left panel). The WT strain incubated with TMR did not shows any signal (right). The maximum intensity projection of the z-stack images (from the 2nd to the last image) is shown. All the images are displayed using the same minimum and maximum intensity values. Bar = 1 μm. (B) Single molecule detection. Representative time traces of RecB-HaloTag spots from same cell (after background subtraction) exhibited single-step photobleaching indicating detection of a single fluorophore.
