title: DNA binding and DNA bending by the MelR transcription activator protein from Escherichia coli.
abstract: The Escherichia coli melR gene encodes MelR protein which is a member of the AraC/XylS family of bacterial transcription activators. The function of MelR was investigated by making a targeted deletion in the melR gene of the Escherichia coli chromosome. MelR is a transcription activator essential for melibiose- dependent expression of the melAB operon which is needed for bacterial growth with melibiose as a carbon source. To investigate the interactions of MelR at the melAB promoter, both full length MelR and a shortened derivative, MelR173, containing the C-terminal DNA-binding domain, were purified as fusions to glutathione- S -transferase. Circular permutation studies show that both full-length MelR and MelR173 induce an apparent bend upon binding to target sites at the melAB promoter. Bound full-length MelR, but not MelR173, can oligomerise to form larger complexes that are likely to be involved in transcription activation.
authors.affiliation: School of Biochemistry, The University of Birmingham, PO Box 363, Birmingham B15 2TT, UK.
authors.forename: S J
authors.initials: SJ
authors.lastname: Bourgerie
authors.forename: C M
authors.initials: CM
authors.lastname: Michán
authors.forename: M S
authors.initials: MS
authors.lastname: Thomas
authors.forename: S J
authors.initials: SJ
authors.lastname: Busby
authors.forename: E I
authors.initials: EI
authors.lastname: Hyde
mesh_terms: D001483:Base Sequence; D001665:Binding Sites; D004269:DNA, Bacterial / Q000737:chemistry / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000302:isolation & purification; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*
chemical_list: D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; C077649:MelR protein, E coli; D011993:Recombinant Fusion Proteins; D015534:Trans-Activators