Nucleic Acids Research, Vol 25, Issue 12 2396-2402, Copyright © 1997 by Oxford University Press
T Thomas, GD Kulkarni, MA Gallo, N Greenfield, JS Lewis, A Shirahata and TJ Thomas
We studied the effects of natural and synthetic polyamines on the
conformation of an oligodeoxyribonucleotide (ODN1) harboring the estrogen
response element (ERE) by circular dichroism (CD) spectroscopy and
polyacrylamide gel electrophoresis. Putrescine and spermidine had no marked
effect on the CD spectrum of ODN1. In contrast, spermine provoked and
stabilized two characteristic changes in the CD spectrum. The first change
was indicated by an increase in the intensity of the CD band at 280 nm at
0.5 mM spermine in Tris-HCl buffer containing 50 mM NaCl. This change
appears to be related to changes in base tilt and conformational
alterations similar to A-DNA. At 1-2 mM spermine, the CD spectrum was
characterized by a loss of positive bands at 220 and 270 nm. This change
might have contributions from polyamine-induced condensation/aggregation of
DNA. Spectral measurements were also conducted in Tris-HCl buffer
containing 150 mM NaCl to minimize contributions from condensation and
aggregation of ODN1. Under these conditions, CD spectral changes were
retained by (ODN1), although the magnitude of the change was diminished. In
contrast, a control oligdeoxyribonucleotide (ODN2) having similar base
composition did not show any significant change in the CD spectrum in the
presence of 150 mM NaCl and 2 mM spermine. The changes in the CD spectrum
of ODN1 were highly sensitive to polyamine structure, as evidenced by
experiments using spermine analogs with altered number of -CH2- groups
separating the amino and imino groups. Electrophoretic mobility shift
analysis further showed ODN1 stabilization by spermine and its analogs.
These data demonstrate the ability of an ODN containing ERE to undergo
conformational transitions in the presence of polyamines and suggest a
possible mechanism for polyamine-mediated alterations in the interaction of
estrogen receptor with ERE.
ARTICLES
Effects of natural and synthetic polyamines on the conformation of an oligodeoxyribonucleotide with the estrogen response element
Department of Environmental and Community Medicine, University of Medicine and Dentistry of New Jersey-Robert Wood Johnson Medical School, New Brunswick, NJ 08903, USA.
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  S K Nair, T J Thomas, N J Greenfield, A Chen, H He, and T Thomas Conformational dynamics of estrogen receptors {alpha} and {beta} as revealed by intrinsic tryptophan fluorescence and circular dichroism J. Mol. Endocrinol., October 1, 2005; 35(2): 211 - 223. [Abstract] [Full Text] [PDF]
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