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Effects of a hairpin polyamide on DNA melting: comparison with distamycin and Hoechst 33258

Effects of a hairpin polyamide on DNA melting: comparison with distamycin and Hoechst 33258
Effects of a hairpin polyamide on DNA melting: comparison with distamycin and Hoechst 33258
We have used DNase I footprinting and fluorescence melting studies to study the interaction of the hairpin polyamide Im-Py-Py-Py-(R)(H2N)gamma-Im`-PY-PY-PY-beta-Dp with its preferred binding sites (5'-WGWWCW; W=A or T) and other sequences. DNase I footprinting confirmed that the ligand binds to the sequence AGAACA at nanomolar concentrations and that changing the terminal A to G causes a dramatic decrease in affinity, while there was no. interaction with the reverse sequence WCWWGW Fluorescence melting studies with I I mer duplexes showed that the polyamide had very different effects on the forward (TGWWCT) and reverse (TCTAGT) sequences. At low concentrations, the polyamide produced biphasic melting curves with TGATCT, TGTACT and TGAACT, suggesting a strong interaction. In contrast, the melting profiles with TCTAGT were always monophasic and showed much smaller concentration dependent changes in T-m. The polyamide also showed weak binding to the sequence TGATCT when one of the central AT pairs was replaced with an AC mismatch. These melting profiles were compared with those produced by the AT-selective minor groove binding agents distamycin and Hoechst 33258 at the same site's and at similar sequences containing A(5) and (AT)(3), which are expected to bind distamycin in the 1:1 and 2:1 modes, respectively. These ligands produced simple monophasic melting curves in which the T-m steadily increased as the ligand concentration was raised.
0301-4622
205-212
James, P.L.
433b1b29-f84f-49eb-bb47-d1caa0b23aa4
Le Strat, L.
74510d69-742e-4c0b-8058-521013e1e72d
Ellervik, U.
7321c745-13e7-415a-afd4-787bcdca033c
Bratwall, C.
2b41733e-bc01-4fd3-a37b-4846087b60fb
Norden, B.
5ce86e67-2639-437d-8d4b-c067fe8ca3a9
Brown, T.
a64aae36-bb30-42df-88a2-11be394e8c89
Fox, K.R.
9da5debc-4e45-473e-ab8c-550d1104659f
James, P.L.
433b1b29-f84f-49eb-bb47-d1caa0b23aa4
Le Strat, L.
74510d69-742e-4c0b-8058-521013e1e72d
Ellervik, U.
7321c745-13e7-415a-afd4-787bcdca033c
Bratwall, C.
2b41733e-bc01-4fd3-a37b-4846087b60fb
Norden, B.
5ce86e67-2639-437d-8d4b-c067fe8ca3a9
Brown, T.
a64aae36-bb30-42df-88a2-11be394e8c89
Fox, K.R.
9da5debc-4e45-473e-ab8c-550d1104659f

James, P.L., Le Strat, L., Ellervik, U., Bratwall, C., Norden, B., Brown, T. and Fox, K.R. (2004) Effects of a hairpin polyamide on DNA melting: comparison with distamycin and Hoechst 33258. Biophysical Chemistry, 111 (3), 205-212.

Record type: Article

Abstract

We have used DNase I footprinting and fluorescence melting studies to study the interaction of the hairpin polyamide Im-Py-Py-Py-(R)(H2N)gamma-Im`-PY-PY-PY-beta-Dp with its preferred binding sites (5'-WGWWCW; W=A or T) and other sequences. DNase I footprinting confirmed that the ligand binds to the sequence AGAACA at nanomolar concentrations and that changing the terminal A to G causes a dramatic decrease in affinity, while there was no. interaction with the reverse sequence WCWWGW Fluorescence melting studies with I I mer duplexes showed that the polyamide had very different effects on the forward (TGWWCT) and reverse (TCTAGT) sequences. At low concentrations, the polyamide produced biphasic melting curves with TGATCT, TGTACT and TGAACT, suggesting a strong interaction. In contrast, the melting profiles with TCTAGT were always monophasic and showed much smaller concentration dependent changes in T-m. The polyamide also showed weak binding to the sequence TGATCT when one of the central AT pairs was replaced with an AC mismatch. These melting profiles were compared with those produced by the AT-selective minor groove binding agents distamycin and Hoechst 33258 at the same site's and at similar sequences containing A(5) and (AT)(3), which are expected to bind distamycin in the 1:1 and 2:1 modes, respectively. These ligands produced simple monophasic melting curves in which the T-m steadily increased as the ligand concentration was raised.

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Published date: 1 November 2004

Identifiers

Local EPrints ID: 56189
URI: http://eprints.soton.ac.uk/id/eprint/56189
ISSN: 0301-4622
PURE UUID: 839bdcc0-1d61-4c2b-adc7-8eddcce7c20b
ORCID for K.R. Fox: ORCID iD orcid.org/0000-0002-2925-7315

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Date deposited: 07 Aug 2008
Last modified: 08 Jan 2022 02:33

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Contributors

Author: P.L. James
Author: L. Le Strat
Author: U. Ellervik
Author: C. Bratwall
Author: B. Norden
Author: T. Brown
Author: K.R. Fox ORCID iD

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