F. Barone et al., gamma-ray footprinting and fluorescence polarization anisotropy of a 30-mer synthetic DNA fragment with one 2 '-deoxy-7-hydro-8-oxognanosine lesion, EUR BIOPHYS, 28(8), 2000, pp. 621-628
Citations number
38
Categorie Soggetti
Biochemistry & Biophysics
Journal title
EUROPEAN BIOPHYSICS JOURNAL WITH BIOPHYSICS LETTERS
The influence of the oxidative lesion 2'-deoxy-7-hydro-8-oxoguanosine (8-ox
odG) on some conformational properties of DNA has been studied. Four 30-mer
duplexes of the form [5'-GATCCTCTAGAGTC[G* or G]ACCTGCAGGCATGCA-3']:[3'-CT
AGGAGATCTCAG[C or A]TGGACGTCCGTACGT-5'], in which G* is the 8-oxodG lesion,
were synthesized in order to compare the effect of the GA mismatch and of
the damaged G*C and G*A forms with the normal GC. Spectroscopic measurement
s performed by means of UV denaturation and circular dichroism experiments
do not show gross changes of stability and overall structure in the damaged
and mismatched samples. The control DNA and the samples containing GA mism
atch show very similar gamma-rays cutting patterns, indicating that the int
roduction of the GA mismatch does not perturb the phosphate backbone geomet
ry. In the samples containing the 8-oxodG there are some variations of the
cleavage pattern near G* which are extended for almost one helical turn. So
me differences are observed between G*C and G*A duplexes. In particular, in
the G*C sample the reduced accessibility to OH radicals at the G15 site, o
bserved in the control, spreads on the intrastrand adjacent bases and in th
e G*A sample a shift of the minimum is observed. The hydrodynamic radius Rh
derived by fluorescence polarization anisotropy decay exhibits a constant
value of 11.4 +/- 0.2 Angstrom between 5 and 40 degrees C, in all the sampl
es. The torsional constant alpha of each oligomer decreases when the temper
ature is raised and the a values of the damaged samples are higher than tho
se of the normal ones.