G. Bakalkin et al., P53 BINDS SINGLE-STRANDED-DNA ENDS THROUGH THE C-TERMINAL DOMAIN AND INTERNAL DNA SEGMENTS VIA THE MIDDLE DOMAIN, Nucleic acids research, 23(3), 1995, pp. 362-369
We have previously reported that wild-type p53 can bind single-strande
d (ss) DNA ends and catalyze renaturation of ss complementary DNA mole
cules. Here we demonstrate that p53 can also bind to internal segments
of ss DNA molecules via a binding site (internal DNA site) distinct f
rom the binding site for DNA ends (DNA end site). Using p53 deletion m
utants, the internal DNA site was mapped to the central region (residu
es 99-307), while the DNA end site was mapped to the C-terminal domain
(residues 320-393) of the p53 protein. The internal DNA site can be a
ctivated by the binding of ss DNA ends to the DNA end site. The C-term
inal domain alone was sufficient to catalyze DNA renaturation, althoug
h the central domain was also involved in promotion of renaturation by
the full-length protein. Our results suggest that the interaction of
the C-terminal tail of p53 with ss DNA ends generated by DNA damage in
vivo may lead to activation of non-specific ss DNA binding by the cen
tral domain of p53.