Molecular Biology Reports

, Volume 14, Issue 1, pp 35–39

Role of calf thymus DNA-Topoisomerase I phosphorylation on relaxation activity expression and on DNA-protein interaction

Role of DNA-Topoisomerase I phosphorylation

Authors

  • S. Coderoni
    • Department of Cell BiologyUniversity of Camerino
  • M. Paperelli
    • Department of Cell BiologyUniversity of Camerino
  • G. L. Gianfranceschi
    • Institute of Cell BiologyUniversity of Perugia
Articles

DOI: 10.1007/BF00422713

Cite this article as:
Coderoni, S., Paperelli, M. & Gianfranceschi, G.L. Mol Biol Rep (1990) 14: 35. doi:10.1007/BF00422713

Abstract

Calf thymus DNA-Topoisomerase I activity was found to be altered by changing in phosphorylation: it was completely inhibited upon dephosphorylation by alkaline phosphatase, but incubation with N II protein kinase and ATP restored the relaxation activity to a level higher than that observed prior to dephosphorylation. The calf thymus Topoisomerase I-mediated DNA cleavage, induced by camptothecin, also proved to be inhibited by dephosphorylation, which, apparently, stabilizes the initial enzymesubstrate complex. We conclude that:
  • - the native protein is partially phosphorylated,

  • - the phosphorylation involvement is essential for the activity expression and also for DNA-protein interaction,

  • - changes in the degree of phosphorylation might be involved in the regulation of DNA processing; that evokes some properties of chromatinic peptide models, which bind DNA only when phosphorylated and leads to the assumption that they represent the minimum functional substrate for N II protein kinase.

Key words

DNA-protein interactionphosphorylation/dephosphorylationTopoisomerase I

Abbreviations

CPT

campothecin

DMSO

dimethyl sulfoxide

DTT

dithiothreitol

PAGE

poly acrylamide gel electrophoresis

SDS

sodium dodecyl sulfate

Topo I

Topoisomerase I

Copyright information

© Kluwer Academic Publishers 1990