FIg. 5.

The rotational dynamics of TaqMutS. The polarization of Cy3-TaqMutS was determined on single DNA molecules (see Fig. 2E). (A) Left: representative time trace of Cy3-TaqMutS on a 100bp duplex DNA in the absence of ATP. Right: population histogram of Cy3-TaqMutS polarization on a 100bp duplex DNA in the absence of ATP. (B) Left: representative time trace of Cy3-TaqMutS on a 100bp DNA containing a +dT mismatch in the absence of ATP. Right: population histogram of Cy3-TaqMutS polarization on a 100bp DNA containing a +dT mismatch in the absence of ATP. (C) Left: representative time trace of Cy3-TaqMutS on a 100 bp DNA containing a +dT mismatch in the presence of ATP. Right: population histogram of Cy3-TaqMutS polarization on a 100 bp DNA containing a +dT mismatch in the presence of ATP. Note that only polarization following sliding clamp formation was plotted (see dashed circle). (D) Illustration of polarization changes associated with rotation of Cy3-TaqMutS on a DNA with a diffusion length greater than one helical pitch (left) or a diffusion length less than one helical pitch (right). Note that the footprint of TaqMutS is 24 bp [112]. Thus, a DNA substrate in which TaqMutS contacts less than one helical pitch must at least accommodate the footprint of the protein. (E) The normalized count of polarized Cy3-TaqMutS on various lengths of duplex DNA. (F) The normalized count of polarized Cy3-TaqMutS on various lengths of DNA containing a +dT mismatch in the presence of ATP. (G) Illustration of the lack of rotational diffusion of TaqMutS on a duplex DNA shorter than 45 bp, and the free rotational diffusion of ATP-bound TaqMutS sliding clamps on DNA containing a +dT mismatch in the presence of ATP.