Table of Contents
Journal of Amino Acids
Volume 2012, Article ID 206083, 8 pages
Research Article

Role of Flexibility in Protein-DNA-Drug Recognition: The Case of Asp677Gly-Val703Ile Topoisomerase Mutant Hypersensitive to Camptothecin

1National Research Council (CNR) and Department of Biology, University of Rome Tor Vergata, Via Della Ricerca Scientifica, Rome 00133, Italy
2CASPUR, Via dei Tizii 6b, Rome 00185, Italy
3Department of Biochemistry “Giovanni Moruzzi,” University of Bologna, Via Irnerio 48, 40126 Bologna, Italy

Received 11 May 2011; Accepted 7 October 2011

Academic Editor: Alice Vrielink

Copyright © 2012 Ilda D'Annessa et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Topoisomerases I are ubiquitous enzymes that control DNA topology within the cell. They are the unique target of the antitumor drug camptothecin that selectively recognizes the DNA-topoisomerase covalent complex and reversibly stabilizes it. The biochemical and structural-dynamical properties of the Asp677Gly-Val703Ile double mutant with enhanced CPT sensitivity have been investigated. The mutant displays a lower religation rate of the DNA substrate when compared to the wild-type protein. Analyses of the structural dynamical properties by molecular dynamics simulation show that the mutant has reduced flexibility and an active site partially destructured at the level of the Lys532 residue. These results demonstrate long-range communication mechanism where reduction of the linker flexibility alters the active site geometry with the consequent lowering of the religation rate and increase in drug sensitivity.