Sl. Grokhovskii et al., SYNTHESIS AND BINDING TO DNA OF 2 PEPTIDES MODELING THE DNA-BINDING DOMAIN OF TRANSCRIPTION ACTIVATOR V-JUN, Molecular biology, 28(5), 1994, pp. 730-737
Synthesis and interaction with DNA of two 26-residue peptides, each co
ntaining in two copies a fragment of the DNA-binding domain of the tra
nscription activator v-Jun, are described. The peptides have identical
amino acid sequence but one is stabilized by an S-S bond between two
cysteine residues. CD spectroscopy showed that both peptides have a ra
ndom conformation in an aqueous solution, and assume a partly alpha-he
lical conformation in the presence of 20% trifluoroethanol. The relati
ve content of alpha-helix increases in the presence of 40% trifluoroet
hanol to approximately 66% and 40%, respectively in the absence and in
the presence of the S-S bond. Obviously the S-S bond hinders the form
ation of alpha-helix within one of the DNA-binding regions of the pept
ide, though an alpha-helix can probably be generated in the other part
. Both peptides were shown to bind to DNA. We revealed that the DNA mi
nor groove-binding antibiotic distamycin A competes effectively with t
he peptide for binding to poly(dA).poly(dT). Binding of the peptide to
DNA induces a conformational transition in the peptide molecule, whil
e the DNA structure does not appreciably change. The difference CD spe
ctra obtained by subtracting the spectrum of free DNA from that of a p
eptide-DNA mixture differs from the spectrum of the free peptide. The
shapes of the difference spectra are consistent with alpha --> beta an
d coil --> beta transitions induced upon binding of the peptides to DN
A. DNase I footprinting diagrams show that the peptides protect the DN
A from cleavage at the regions containing 5'-TGA-3' and 5'-TGC-3' sequ
ences.