The effect of 9-beta-D-arabinofuranosyl-2-fluoroadenine and 1-beta-D-arabinofuranosylcytosine on the cell cycle phase distribution, topoisomerase II level, mitoxantrone cytotoxicity, and DNA strand break production in K562 human leukemia cells

The UvrA and UvrB proteins form part of the UvrABc endonuclease, which is responsible for nucleotide excision repair in Escherichia coli. Using a mobility shift gel assay we have studied the binding of UvrA dimer, UvrB monomer and UvA(2)B trimer complexes with 40, 50 and 136 bp (32)P-end-labelled DNA fragments adducted with aflatoxin B(1). UvrA was shown to re-associate with adduct specific UvrB: DNA complexes, a phenomenon which could be reversed by the addition of 500 mM potassium chloride or anti-UvrA anti-sera. Re-association was shown to be UvrA concentration dependent. Re-association of UvrA(2)B to the UvrB:DNA complex was not seen. We have also shown that the UvrB:DNA complex, in the case of aflatoxin B(1), is extremely stable with a half-life excess of 400 min and that fragment termini are not a specific substrate for UvrA binding.