Modifying the N-terminus of polyamides: PyImPyIm has improved sequence specificity over f-ImPyIm
摘要:
Seven N-terminus modified derivatives of a previously published minor-groove binding polyamide (f-ImPyIm, 1) were synthesized and the biochemical and biophysical chemistry evaluated. These compounds were synthesized with the aim of attaining a higher level of sequence selectivity over f-ImPyIm (1), a previously published strong minor-groove binder. Two compounds possessing a furan or a benzofuran moiety at the N-terminus showed a footprint of 0.5 mu M at the cognate ACGCGT site (determined by DNase I footprinting); however, the specificity of these compounds was not improved. In contrast, PyImPyIm (4) produced a footprint of 0.5 mu M but showed a superior specificity using the same technique. When evaluated by thermal melting experiments and circular dichroism using ACGCGT and the non-cognate AAATTT sequence, all compounds were shown to bind in the minor-groove of DNA and stabilize the cognate sequence much better than the non-cognate (except for the non-amido-compound that did not bind either sequence, as expected). PyImPyIm (4) was interesting as the Delta T(m) for this compound was only 4 degrees C but the footprint was very selective. No binding was observed for this compound with a third DNA (non-cognate, ACCGGT). ITC studies on compound 4 showed exothermic binding with ACGCGT and no heat change was observed for titrating the compound to the other two DNA sequences. The heat capacity (Delta C(p)) of the PIPI/ACGCGT complex calculated from the hydrophobic interactions and SASA calculations was comparable to the experimental value obtained from ITC (-146 cal mol(-1) K(-1)). SPR results provided con. firmation of the sequence specificity of PyImPyIm (4), with a K(eq) value determined to be 7.1 x 10(6) M(-1) for the cognate sequence and no observable binding to AAATTT and ACCGGT. Molecular dynamic simulations affirmed that PyImPyIm (4) binds as a dimer in an overlapped conformation, and it fits snugly in the minor-groove of the ACGCGT oligonucleotide. PyImPyIm (4) is an especially interesting molecule, because although the binding affinity is slightly reduced, the specificity with respect to f-ImPyIm (1) is significantly improved. (C) 2008 Elsevier Ltd. All rights reserved.
Modifying the N-terminus of polyamides: PyImPyIm has improved sequence specificity over f-ImPyIm
作者:Toni Brown、Hilary Mackay、Mark Turlington、Arden Sutterfield、Traci Smith、Alan Sielaff、Laura Westrate、Chrystal Bruce、Jerome Kluza、Caroline O’Hare、Binh Nguyen、W. David Wilson、John A. Hartley、Moses Lee
DOI:10.1016/j.bmc.2008.03.008
日期:2008.5
Seven N-terminus modified derivatives of a previously published minor-groove binding polyamide (f-ImPyIm, 1) were synthesized and the biochemical and biophysical chemistry evaluated. These compounds were synthesized with the aim of attaining a higher level of sequence selectivity over f-ImPyIm (1), a previously published strong minor-groove binder. Two compounds possessing a furan or a benzofuran moiety at the N-terminus showed a footprint of 0.5 mu M at the cognate ACGCGT site (determined by DNase I footprinting); however, the specificity of these compounds was not improved. In contrast, PyImPyIm (4) produced a footprint of 0.5 mu M but showed a superior specificity using the same technique. When evaluated by thermal melting experiments and circular dichroism using ACGCGT and the non-cognate AAATTT sequence, all compounds were shown to bind in the minor-groove of DNA and stabilize the cognate sequence much better than the non-cognate (except for the non-amido-compound that did not bind either sequence, as expected). PyImPyIm (4) was interesting as the Delta T(m) for this compound was only 4 degrees C but the footprint was very selective. No binding was observed for this compound with a third DNA (non-cognate, ACCGGT). ITC studies on compound 4 showed exothermic binding with ACGCGT and no heat change was observed for titrating the compound to the other two DNA sequences. The heat capacity (Delta C(p)) of the PIPI/ACGCGT complex calculated from the hydrophobic interactions and SASA calculations was comparable to the experimental value obtained from ITC (-146 cal mol(-1) K(-1)). SPR results provided con. firmation of the sequence specificity of PyImPyIm (4), with a K(eq) value determined to be 7.1 x 10(6) M(-1) for the cognate sequence and no observable binding to AAATTT and ACCGGT. Molecular dynamic simulations affirmed that PyImPyIm (4) binds as a dimer in an overlapped conformation, and it fits snugly in the minor-groove of the ACGCGT oligonucleotide. PyImPyIm (4) is an especially interesting molecule, because although the binding affinity is slightly reduced, the specificity with respect to f-ImPyIm (1) is significantly improved. (C) 2008 Elsevier Ltd. All rights reserved.