DNA translocation by type III restriction enzymes: A comparison of current models of their operation derived from ensemble and single-molecule measurements

  • Dryden D
  • Edwardson J
  • Henderson R
  • 22


    Mendeley users who have this article in their library.
  • 13


    Citations of this article.


Much insight into the interactions of DNA and enzymes has been obtained using a number of single-molecule techniques. However, recent results generated using two of these techniques-atomic force microscopy (AFM) and magnetic tweezers (MT)-have produced apparently contradictory results when applied to the action of the ATP-dependent type III restriction endonucleases on DNA. The AFM images show extensive looping of the DNA brought about by the existence of multiple DNA binding sites on each enzyme and enzyme dimerisation. The MT experiments show no evidence for looping being a requirement for DNA cleavage, but instead support a diffusive sliding of the enzyme on the DNA until an enzyme-enzyme collision occurs, leading to cleavage. Not only do these two methods appear to disagree, but also the models derived from them have difficulty explaining some ensemble biochemical results on DNA cleavage. In this 'Survey and Summary', we describe several different models put forward for the action of type III restriction enzymes and their inadequacies. We also attempt to reconcile the different models and indicate areas for further experimentation to elucidate the mechanism of these enzymes.

Get free article suggestions today

Mendeley saves you time finding and organizing research

Sign up here
Already have an account ?Sign in

Find this document


Error loading document authors.

Cite this document

Choose a citation style from the tabs below

Save time finding and organizing research with Mendeley

Sign up for free