Steric and electrostatic effects in DNA synthesis by the SOS-induced DNA polymerases II and IV of Escherichia coli.

ABSTRACT: The SOS-induced DNA polymerases II and IV (pol II and pol IV, respectively) of Escherichia coli play important roles in processing lesions that occur in genomic DNA. Here we study how electrostatic and steric effects play different roles in influencing the efficiency and fidelity of DNA synthesis by these two enzymes. These effects were probed by the use of nonpolar shape analogues of thymidine, in which substituted toluenes replace the polar thymine base. We compared thymine with nonpolar analogues to evaluate the importance of hydrogen bonding in the polymerase active sites, while we used comparisons among a set of variably sized thymine analogues to measure the role of steric effects in the two enzymes. Steady-state kinetics measurements were carried out to evaluate activities for nucle

SUBMITTER: Silverman AP 

PROVIDER: S-EPMC2555966 | biostudies-literature | 2007 Dec

REPOSITORIES: biostudies-literature