The mechanism of type IA topoisomerases
Publication Type:
Journal ArticleSource:
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.132378799Keywords:
ENZYMES; ESCHERICHIA-COLI; GYRASE; HELICASE; POSITIVELY SUPERCOILED DNA; RELAXATION; SINGLE-MOLECULEAbstract:
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.