DNA-binding studies of XSPTSPSZ, derivatives of the intercalating heptad repeat of RNA polymerase II
✍ Scribed by Margaret M. Harding; Guy Y. Krippner; Cathryn J. Shelton; Alison Rodger; Karen J. Sanders; Joel P. Mackay; Arungundrum S. Prakash
- Publisher
- Wiley (John Wiley & Sons)
- Year
- 1997
- Tongue
- English
- Weight
- 176 KB
- Volume
- 42
- Category
- Article
- ISSN
- 0006-3525
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✦ Synopsis
The synthesis, solution conformation, and interaction with DNA of three 8-residue peptides structurally related to the heptad repeat unit found at the C-terminus of RNA polymerase II are reported. Peptides QQ, XQ, and PQ are derived from the parent sequence YSPTSPSY (peptide YY), which was reported to bind to DNA by bisintercalation [M. Suzuki (1990) Nature, Vol. 344, pp. 562-565], and contain either a 2-quinolyl (Q), 2-quinoxolyl (X), or 5phenanthrolyl (P) group in place of the aromatic side chains of the N-and C-terminal tyrosine residues present in the parent sequence. The combined results of linear dichroism and induced CD measurements of peptides QQ, XQ, and PQ with calf thymus DNA are consistent with weak binding of the peptides to DNA in a preferred orientation in which the chromophores are intercalated. Small increases in the melting temperatures of poly[d(A-T) 2 ] are also consistent with the peptides interacting with DNA. While enzymatic footprinting with DNase I showed no protection from cleavage by the enzyme, chemical footprinting with fotemustine showed that the peptides modify the reactivity of the major groove, presumably via minor groove binding. Peptide QQ inhibited fotemustine alkylation significantly more than either XQ or PQ, and