Integrated Polymerase and Exonuclease Activities of Escherichia Coli DNA Polymerase I on Platinated DNA

Abstract

Escherichia coli DNA polymerase I was chosen as a model for integrated enzymatic DNA polymerization and excision repair system acting on DNA that was coordinated to cis-diammineplatinum (II) (cis-DDP) or trans-diammineplatinum(II) (trans-DDP), respectively. The protein inherent DNA polymerization, 3′-5′-exonuclease and 5′-3′-exonuclease activities have been measured following incorporation or excision of radioactively labelled nucleotides in/from platinated DNA. The activities were measured as a function of kinetics of DNA platination. Correlation of observed inhibition with previously established kinetics of platination of DNA (1) revealed the stage at which platinum adducts became inhibitory, in particularly whether they were of the monofunctional or crosslinking type.