Interaction with DNA of oligopeptides related to the Arc repressor.

Abstract

Three different peptides, A13, A14x2 and A20, related to the Arc repressor from Salmonella phage P22, were synthesized. They all contained the 13 N-terminal residues of Arc known to form a beta-sheet interacting with the operator OArc. In the case of A20, the tripeptide Lys-Trp-Lys was added in the C-terminal position because of its propensity to increase affinity to DNA. The interaction of the three peptides with OArc and with other related (OMnt from the same phage) and unrelated oligonucleotides was followed using circular dichroism, filter binding assays and DNaseI protection experiments. While Kd = 10(-9) M for the protein, 8.7 x 10(-5) M and 7.7 x 10(-6) M Kd values were obtained for A14x2 and A20 interacting with OArc.