DNA recognition of a 24-mer peptide derived from RecA protein

A novel 24-residue peptide (L2-G), Ile-Arg-Met-Lys-Ile-Gly-Val-Met-Phe-Gly-Asn-Pro-Glu-Thr-Thr-Thr-Gly-Gly-Asn-Ala-Leu-Lys-Phe-Tyr, derived from RecA can discriminate a single-stranded DNA (ssDNA) from a double-stranded DNA (dsDNA) and a new developed support with this peptide recognizes not dsDNA but ssDNA. The 24-mer peptide with L2 and helix G amino acids of Escherichia coli RecA protein showed the ssDNA binding property with more than 1000 times affinity difference for the dsDNA. However, truncated 15-mer peptide showed no ssDNA binding activity. In the ssDNA binding, L2-G changed its conformation with the perturbation of an alpha-helix structure. The ssDNA binding and the DNA discrimination property of this peptide were due to almost all L2 and helix G amino acids, respectively. This result is useful to design synthetic peptides as functional materials for DNA recognition.