Sequence determinants of DNA bending in the ilvlH promoter and regulatory region of Escherichia coli
Journal - Nucleic Acids Research
Previous studies have shown that the promoter/ regulatory regionof the IlvlH operon displays intrinsic curvature, with the bendcenter located at position -120 relative to the transcriptionstart site. In this report, a 57 bp sequence spanning the bendcenter was mutagenlzed In vitro In order to study the relationshipbetween nucleotlde sequence and curvature measured by electrophoresis.The strategy used for analyzing the results consisted of determiningthe strengths of the relationships between electrophoretic anomalyand predicted curvature calculated by computer programs thatdiffer in wedge angle composition. The results revealed thatprograms which assume that bending occurs only at AA/TT displaygood predictive value, with correlation coefficients betweenelectrophoretic anomaly and predicted curvature as high as 0.93.In contrast, a program which assumes that bending occurs atall 16 dinucleotlde steps exhibited lower predictive value,while there were no significant relationships between the experimentaldata and curvature calculated by a program that was based onall non-AA/TT wedge values. These results show that the completewedge model which incorporates values for all dinucleotlde stepsdoes not adequately describe the electrophoretic data In thisreport.