Effects of supercoiling on the sequence-specific photo-modification of DNA by a vanadium(V)-peroxo complex

Sequence-specific photo-modification of DNA has been demonstrated, for the first time, in a vanadium(V)-peroxo complex, NH4[VO(O2)2(5,6-Me2phen)] (where 5,6-Me2phen = 5,6-dimethyl-1,10-phenanthroline). Using molecular cloning technique, a consensus sequence motif of 5′-G(A/G)TA(T/C)C was identified associated with the two specific photo-modification sites, 5′-ATC and 5′-TACC found on a plasmid DNA, pBluescript, by a modified Sanger sequencing technique. DNA supercoiling was shown to be a critical prerequisite for this observed sequence-specific photo-modification activity.