STRUCTURAL CHARACTERIZATION OF INTRINSICALLY CURVED AT-RICH DNA-SEQUENCES

AT-rich DNA sequences other than A(n)T(m) tracts (n + m greater than o r equal to 4) are known to be intrinsically curved. The AATAT-element constitutes one known example of these sequences. in this paper, the e lucidation of the structural basis of the curvature induced by this se quence element was addressed. As judged by the patterns of cleavage by the hydroxyl radical and DNase I, the AATAT sequence shows a narrow m inor groove. Furthermore, the 5' adenine residue of the AA dinucleotid e contained within the sequence is hyperreactive to diethylpyrocarbona te. Similar structural properties are shown by several sequences induc ing intrinsic DNA curvature, such as an A(5)-tract or the closely rela ted ATAAT, AATATA and TAATAT sequences, which are also shown here to i nduce curvature. On the other hand, other related sequences, such as T ATAA and ATATA, that do not induce curvature, show different structura l characteristics.