title: Design and synthesis of sequence-specific DNA-binding peptides.
abstract: Design, synthesis and DNA binding activities of two peptides containing 32 and 102 residues are reported. A nonlinear 102-residue peptide contains four modified alpha helix-turn-alpha helix motifs of 434 cro protein. These four units are linked covalently to a carboxyterminal crosslinker containing four arms each ending with an aliphatic amino group. From CD studies we have found that in aqueous buffer in the presence of 20% trifluoroethanol the peptide residues assume alpha-helical, beta-sheet and random-coiled conformations with the alpha-helical content of about 16% at room temperature. Upon complex formation between peptide and DNA, a change in the peptide conformation takes place which is consistent with an alpha - beta transition in the DNA binding alpha helix-turn-alpha helix units of the peptide. Similar conformation changes are observed upon complex formation with the synthetic operator of a linear peptide containing residues 7-37 of 434 cro repressor. Evidently, in the complex, residues present in helices alpha 2 and alpha 3 of the two helix motif form a beta-hairpin which is inserted in the minor DNA groove. The last inference is supported by our observations that the two peptides can displace the minor groove-binding antibiotic distamycin A from poly(dA).poly(dT) and synthetic operator DNA. As revealed from DNase digestion studies, the nonlinear peptide binds more strongly to a pseudooperator Op1, located in the cro gene, than to the operator OR3. A difference in the specificity shown by the non-linear peptide and wild-type cro could be attributed to a flexibility of the linker chains between the DNA-binding domains in the peptide molecule as well as to a replacement of Thr-Ala in the peptide alpha 2-helices. Removal of two residues from the N-terminus of helix alpha 2 in each of the four DNA-binding domains of the peptide leads to a loss of binding specificity.
authors.affiliation: W.A. Engelhardt Institute of Molecular Biology, Academy of Sciences of the USSR, Moscow.
authors.forename: S L
authors.initials: SL
authors.lastname: Grokhovsky
authors.forename: A N
authors.initials: AN
authors.lastname: Surovaya
authors.forename: R V
authors.initials: RV
authors.lastname: Brussov
authors.forename: B K
authors.initials: BK
authors.lastname: Chernov
authors.lastname: Sidorova NYu
authors.forename: G V
authors.initials: GV
authors.lastname: Gursky
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001435:Bacteriophages / Q000235:genetics; D001483:Base Sequence; D002942:Circular Dichroism; D004279:DNA, Viral / Q000737:chemistry / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000138:chemical synthesis / Q000737:chemistry* / Q000378:metabolism; D003850:Deoxyribonuclease I / Q000378:metabolism; D004214:Distamycins / Q000737:chemistry; D015195:Drug Design; D008969:Molecular Sequence Data; D009875:Operator Regions, Genetic; D011067:Poly dA-dT / Q000737:chemistry; D011487:Protein Conformation; D012097:Repressor Proteins / Q000737:chemistry* / Q000378:metabolism; D013696:Temperature; D014764:Viral Proteins; D054334:Viral Regulatory and Accessory Proteins
chemical_list: D004279:DNA, Viral; D004268:DNA-Binding Proteins; D004214:Distamycins; D012097:Repressor Proteins; D014764:Viral Proteins; D054334:Viral Regulatory and Accessory Proteins; C016649:phage repressor proteins; D011067:Poly dA-dT; C030000:stallimycin; D003850:Deoxyribonuclease I