The mechanism of type IA topoisomerases

Publication Type:

Journal Article

Source:

PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, NATL ACAD SCIENCES, Volume 99, Number 19, 2101 CONSTITUTION AVE NW, WASHINGTON, DC 20418 USA, p.12126-12131 (2002)

DOI:

10.1073/pnas.132378799

Keywords:

ENZYMES; ESCHERICHIA-COLI; GYRASE; HELICASE; POSITIVELY SUPERCOILED DNA; RELAXATION; SINGLE-MOLECULE

Abstract:

The topology of cellular DNA is carefully controlled by enzymes called topoisomerases. By using single-molecule techniques, we monitored the activity of two type IA topoisomerases in real time under conditions in which single relaxation events were detected. The strict one-at-a-time removal of supercoils we observed establishes that these enzymes use an enzyme-bridged strand-passage mechanism that is well suited to their physiological roles and demonstrates a mechanistic unity with type II topoisomerases.