DNA bending by Saccharomyces cerevisiae ABF1 and its proteolytic fragments

The ABF1 protein of the yeast Saccharomyces cerevisiae has been found to bend the DNA containing the target site for DNA binding. A bend angle of about 120 degrees was measured and the bend center was 7 base pairs to the 5' end of the ABF1 consensus-containing sequence. Phasing analysis showed that intact ABF1 bends the DNA towards the minor groove. We have subjected ABF1 to partial proteolysis and have found that proteolytic fragments were able to bind to the DNA-binding site and induce partial bends in the DNA. Interestingly, the locations of the bend centers, the bend angles, and the plane of the bends induced by the proteolytic peptides of ABF1 were different from those of the intact protein. We present a model for the mechanism of bending of DNA by ABF1.