R K Beran-Steed

Learn More
Escherichia coli DNA topoisomerase I catalyzes interconversions of different DNA topological isomers by the breakage and rejoining of DNA phosphodiester bonds. It has a crucial role in maintaining an optimal DNA superhelicity in E. coli. It is a single polypeptide of 864 amino acids. Analysis of the amino acid sequence reveals three tandem repeat units each(More)
To study the protein-protein interactions that allow Id, a negative regulator of cell differentiation, to inhibit the DNA-binding activities of MyoD and E47, we have synthesized peptides corresponding to the helix-loop-helix domains of MyoD, E47, and Id. We show that Id preferentially inhibits the sequence-specific DNA-binding activity of MyoD, a(More)
Limited digestion of E. coli DNA topoisomerase I with trypsin or papain generated a DNA-binding domain of MW 14,000 corresponding to the carboxyl terminal of the enzyme. This fragment binds to single-stranded DNA agarose as tightly as the intact enzyme. It required around 400 mM NaCl for elution. A truncated topoisomerase that lacks this C-terminal domain(More)
E47 is an immunoglobulin enhancer DNA-binding protein that contains a basic region-helix-loop-helix (b/HLH) domain. This structural motif defines a class of transcription factors that are central to the developmental regulation of many tissues. Its function is to provide a dimerization interface through the formation of a parallel four-helix bundle,(More)
  • 1