Figure 5.
Effects of hydrogen bond forming mutations at P-1 and P-2 in the variable regions of orfZαE3L on B to Z-DNA conversion activity. Kinetic measurements of DNA conformation change from B-DNA to Z-DNA in orfZαE3L (green) and its variable region mutants—orfZαE3LGN5455TN (blue), orfZαE3LGN5455TT (blue) and orfZαE3LGN5455GT (black)—were carried out to investigate effects of hydrogen bond forming potentials by amino acid residues in the variable region (P-1 and P-2). When both amino acid residues at P-1 and P-2 have abilities to form hydrogen bond(s), these mutants show better B to Z-DNA conversion activities than wild types or other mutants that have Gly (orfZαE3L) or Ala (spZαE3L) at P-2 position, respectively. This may indicate that the amino acid residue at P-2 could contribute to B to Z-DNA conversion possibly by hydrogen-bond interaction(s) with Z-DNA backbones as is found in P-1.