J. Kim et al., INTRINSICALLY BENT DNA IN A EUKARYOTIC TRANSCRIPTION FACTOR RECOGNITION SEQUENCE POTENTIATES TRANSCRIPTION ACTIVATION, The Journal of biological chemistry, 270(3), 1995, pp. 1282-1288
Many eukaryotic transcription factors induce DNA bending on binding to
their recognition sequences. DNA bending could play a structural role
by altering contacts between the protein and DNA. Alternatively, DNA
bending could play a more direct role in transcription activation. To
distinguish between these possibilities, we inserted two to eight copi
es of the intrinsic bending sequence, AAAAAACGTG, into a minimal promo
ter containing only a TATA box. The intrinsic DNA bending sequence was
a potent activator of transcription in both in vivo transfection expe
riments and in a cell-free transcription system. A protein binds to th
e intrinsic bending sequence with high specificity in gel mobility shi
ft assays and was required for its transcription in cell-free extracts
, The intercalator, distamycin, which eliminates the ability of the se
quence to bend, specifically reduced its transcription by about 60%. M
utations in the sequence which abolished DNA bending reduced transcrip
tion by approximately 70% in vivo. Competition gel mobility shift assa
ys showed that the transcription factor bound equally well to mutants
in which DNA bending was abolished and to the intrinsic bending sequen
ce. These data indicate that DNA bending can play a direct role in the
activation of eukaryotic transcription.