title: Oligomeric interaction of the PapB transcriptional regulator with the upstream activating region of pili adhesin gene promoters in Escherichia coli.
abstract: Transcriptional regulation of the pap genes, which encode fimbrial adhesins in uropathogenic Escherichia coli, depends on an upstream activating region. This region contains binding sites for a transcription factor, PapB, which is a member of a growing family of putative regulatory proteins found in several virulence-associated fimbrial gene systems. To assess the nature of the PapB binding sites, we studied different naturally occurring variants and a number of in vitro constructed mutant binding sites. DNase I footprinting analysis and visualization of the PapB-DNA complex by atomic force microscopy showed that the protein occupied a DNA region of more than 50 bp. Purified PapB protein was shown to recognize a motif including a 9 bp repeat sequence containing T/A triplets at a conserved position. PapB binding was affected by distamycin, and the results were consistent with the possibility that the binding to DNA occurred through minor groove interaction. From these analyses and estimation of the relative number of PapB proteins per binding site, we suggest that PapB binds the DNA in an oligomeric fashion and may function as an architectural factor in the transcriptional control of adhesin expression.
authors.affiliation: Department of Microbiology, Umeâ University, S-90187 Umeâ, Sweden.
authors.forename: Y
authors.initials: Y
authors.lastname: Xia
authors.forename: K
authors.initials: K
authors.lastname: Forsman
authors.forename: J
authors.initials: J
authors.lastname: Jass
authors.forename: B E
authors.initials: BE
authors.lastname: Uhlin
mesh_terms: D018829:Adhesins, Bacterial / Q000235:genetics*; D001426:Bacterial Proteins / Q000235:genetics / Q000648:ultrastructure; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D001667:Binding, Competitive / Q000235:genetics; D018983:DNA Footprinting; D004269:DNA, Bacterial / Q000648:ultrastructure; D004268:DNA-Binding Proteins / Q000032:analysis / Q000235:genetics; D004214:Distamycins / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics*; D029968:Escherichia coli Proteins; D015964:Gene Expression Regulation, Bacterial / Q000235:genetics*; D007763:Lac Operon / Q000235:genetics; D008565:Membrane Proteins; D018625:Microscopy, Atomic Force; D008969:Molecular Sequence Data; D009154:Mutation; D012689:Sequence Homology, Nucleic Acid; D014157:Transcription Factors / Q000235:genetics*
chemical_list: D018829:Adhesins, Bacterial; D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; D004214:Distamycins; D029968:Escherichia coli Proteins; D008565:Membrane Proteins; D014157:Transcription Factors; C116245:atpD protein, E coli; C030000:stallimycin