1: Nature  2001 Jan 4;409(6816):113-5 

Direct observation of DNA rotation during transcription by Escherichia coli RNA
polymerase.

Harada Y, Ohara O, Takatsuki A, Itoh H, Shimamoto N, Kinosita K Jr.

Department of Physics, Faculty of Science and Technology, Keio University,
Hiyoshi 3-14-1, Kohoku-ku, Yokohama 223-8522, Japan. yharada@rinshoken.or.jp

Helical filaments driven by linear molecular motors are anticipated to rotate
around their axis, but rotation consistent with the helical pitch has not been
observed. 14S dynein and non-claret disjunctional protein (ncd) rotated a
microtubule more efficiently than expected for its helical pitch, and myosin
rotated an actin filament only poorly. For DNA-based motors such as RNA
polymerase, transcription-induced supercoiling of DNA supports the general
picture of tracking along the DNA helix. Here we report direct and real-time
optical microscopy measurements of rotation rate that are consistent with
high-fidelity tracking. Single RNA polymerase molecules attached to a glass
surface rotated DNA for >100 revolutions around the right-handed screw axis of
the double helix with a rotary torque of >5 pN nm. This real-time observation of
rotation opens the possibility of resolving individual transcription steps.

PMID: 11343125 [PubMed - indexed for MEDLINE]