S. Raghunathan, C.S. Ricard, T.M. Lohman, and G. Waksman.
Crystal structure of the homo-tetrameric DNA binding domain of
Escherichia coli single-strand DNA binding protein
determined by multiwavelength x-ray diffraction on the selenomethionyl protein
at 2.9-A resolution.
The crystal structure of the tetrameric DNA-binding domain of the single-stranded
DNA binding protein from Escherichia coli was determined at a resolution of
2.9 A using multiwavelength anomalous dispersion. Each monomer in the tetramer is
topologically equivalent to an oligomer-binding fold. Two monomers each contribute
three beta-strands to a single six-stranded beta-sheet to form a dimer. Two dimer-dimer
interfaces are observed within the crystal. One of these stabilizes the tetramer in
solution. The other interface promotes a superhelical structure within the crystal
that may reflect tetramer-tetramer interactions involved in the positive cooperative
binding of the single-stranded DNA binding protein to single-stranded DNA.
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