doi:10.1016/j.bmcl.2003.11.068
Copyright © 2003 Elsevier Ltd. All rights reserved.
DNA binding of a short lexitropsin
Nahoum G. Anthony b, c, Keith R. Fox a, Blair F. Johnston c, Abedawn I. Khalaf b, Simon P. Mackay c, Iain S. McGroarty c, John A. Parkinson b, Graham G. Skellern c, Colin J. Suckling
,
, b and Roger D. Waigh c
a Department of Physiology and Pharmacology, School of Biological Sciences, University of Southampton, Bassett Crescent East, Southampton SO9 3TU, UK
b Department of Pure and Applied Chemistry, University of Strathclyde, 295 Cathedral Street, Glasgow G1 1XL, UK
c Department of Pharmaceutical Sciences, University of Strathclyde, 27 Taylor Street, Glasgow G4 0NR, UK
Received 25 July 2003;
Revised 12 November 2003;
accepted 18 November 2003.
Available online 19 February 2004.
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Abstract
Footprinting, capillary electrophoresis, molecular modelling and NMR studies have been used to examine the binding of a short polyamide to DNA. This molecule, which contains an isopropyl-substituted thiazole in place of one of the N-methylpyrroles, is selective for the sequence 5′-ACTAGT-3′ to which it binds with high affinity. Two molecules bind side-by-side in the minor groove, but their binding is staggered so that the molecule reads six base pairs, unlike the related natural products, which tend to bind to four-base-pair sequences. The result suggests that high affinity and selectivity may be gained without resort to very large molecules, which may be difficult to deliver to the site of action.
Abstract; Graphical Abstract;
Graphical Abstract
Footprinting, capillary electrophoresis, molecular modelling and NMR studies have been used to examine the binding of 5 to DNA. This molecule, which contains an isopropyl-substituted thiazole in place of one of the N-methylpyrroles, is selective for the sequence 5′-ACTAGT-3′ to which it binds with high affinity. Two molecules bind side-by-side in the minor groove, but their binding is staggered so that the molecule reads six base pairs, unlike the related natural products, which tend to bind to four-base-pair sequences. The result suggests that high affinity and selectivity may be gained without resort to very large molecules, which may be difficult to deliver to the site of action.
Figure 1. Surface of DNA minor groove in a region composed of A/T base pairs only. Red coloration indicates areas of negative charge.
Figure 2. DNase I footprinting data for lexitropsins 3, 4 and 5. The first three panels used tyrT DNA as the footprinting substrate; the numbering scheme is the same as in previous publications.[10] The last two panels show the interaction of 5 with fragments MS1 and MS. [11] These fragments contain the same sequence in opposite orientations and are designed to contain all possible four-base-pair sequences. The ligand concentration (μM) is shown at the top of each gel lane; con indicates control while GA is a sequence marker specific for purines. The location of the footprints is indicated.
Figure 3. Schematic representation of the minor-groove binding mode between 5 and d(CGACTAGTCG) showing the six base-pair overlap which results from the staggered nature of the relationship between the two occupying ligands. Green, formyl ‘head’; red, N-methyl pyrrole; yellow, thiazole; blue, DMAP ‘tail’.
Figure 4. NMR-derived structure of the complex between 5 and 5′-CGACTAGTCG.