title: Characterization of BNT2, an intrinsically curved DNA of Escherichia coli O157:H7.
abstract: The gene regulation by intrinsically curved DNA is one way for bacterial sensing of and response to environmental changes. Previously, we showed that the genetic element BNT2 upstream of the ecf (eae-positive conserved fragment) operon in the Escherichia coli O157:H7 virulence plasmid (pO157) has characteristics typical of intrinsically curved DNA, including the presence of multi-homopolymeric adenine:thymine tracts (AT tracts) and electrophoretic anomaly at 4 degrees C. Here we report that a local intrinsic curvature induced by the two phased AT tracts within the unusual promoter sequence of BNT2 played a major role for its temperature-dependent promoter activity. The base substitution of the AT tract in the spacer DNA between the -35 and the unusual -10 regions of the BNT2 promoter with non-AT tract sequence reduced intrinsic curvature slightly at 4 degrees C, but greatly affected its transcriptional activity. This implies that such a local intrinsic curvature within the unusual promoter of BNT2 is important for thermoregulation of the ecf operon.
authors.affiliation: Department of Microbiology and Research Institute for Translational System Biomics, Chung-Ang University College of Medicine, Seoul 156-756, Republic of Korea. jwy706@gmail.com
authors.forename: Jang W
authors.initials: JW
authors.lastname: Yoon
authors.forename: Moon K
authors.initials: MK
authors.lastname: Park
authors.forename: Carolyn J
authors.initials: CJ
authors.lastname: Hovde
authors.forename: Seung-Hak
authors.initials: SH
authors.lastname: Cho
authors.forename: Jong-Chul
authors.initials: JC
authors.lastname: Kim
authors.forename: Mi-Sun
authors.initials: MS
authors.lastname: Park
authors.forename: Wonyong
authors.initials: W
authors.lastname: Kim
mesh_terms: D001483:Base Sequence; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics*; D019453:Escherichia coli O157 / Q000235:genetics*; D015964:Gene Expression Regulation, Bacterial; D016297:Mutagenesis, Site-Directed; D009690:Nucleic Acid Conformation; D009876:Operon; D011401:Promoter Regions, Genetic
chemical_list: D004269:DNA, Bacterial