Structural and Functional Studies of the Fimbrial Adhesin Gene Regulator papB from Uropathogenic Escherichia coli
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.
The DNA binding saturation results and visualization of DNA-PapB complex by AFM suggested that PapB can bind DNA in an oligomeric fashion.
Mutations altering Arg61 or Cys65 caused deficiency in DNA binding, indicating that these residues are critical for PapB binding to DNA. Alanine substitutions at positions 35–36, 53–56, and 74–76 resulted in mutants that were impaired in oligomerization.
The transcriptional efficiency of all the mutants was clearly reduced as compared with that of wild-type PapB, indicating that both DNA binding and oligomerization are required for PapB as a transcriptional regulator.
KeywordsAlanine Substitution Transcriptional Efficiency Strain KS71 Binding Saturation Experiment Pilus Biogenesis
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