Abstract
We have determined the crystal structure, at 3.2 A, of a ternary complex containing an OCA-B peptide, the Oct-1 POU domain, and an octamer DNA site. The OCA-B peptide binds in the major groove near the center of the octamer site, and its polypeptide backbone forms a pair of hydrogen bonds with the adenine base at position 5 of the octamer DNA. Numerous protein-protein contacts between the OCA-B peptide and the POU domain are also involved in the ternary complex. In particular, the hydrophobic surface from a short alpha-helix of OCA-B helps to stabilize the complex by binding to a hydrophobic pocket on the POU-specific domain. The structure of this ternary complex is consistent with previous biochemical studies and shows how peptide-DNA and peptide-protein contacts from OCA-B provide structural and functional specificity in the regulation of immunoglobulin transcription.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, Non-P.H.S.
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Amino Acid Sequence
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Animals
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Base Sequence
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Binding Sites / genetics
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Crystallography, X-Ray
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DNA / chemistry*
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DNA / genetics
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DNA / metabolism
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DNA-Binding Proteins / genetics*
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Host Cell Factor C1
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Humans
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Macromolecular Substances
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Models, Molecular
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Molecular Sequence Data
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Nucleic Acid Conformation
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Octamer Transcription Factor-1
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Peptide Fragments / chemistry
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Peptide Fragments / genetics
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Peptide Fragments / metabolism
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Protein Conformation
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Recombinant Proteins / chemistry
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Recombinant Proteins / genetics
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Recombinant Proteins / metabolism
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Static Electricity
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Trans-Activators / chemistry*
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Trans-Activators / genetics
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Trans-Activators / metabolism
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Transcription Factors / genetics*
Substances
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DNA-Binding Proteins
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HCFC1 protein, human
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Host Cell Factor C1
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Macromolecular Substances
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Octamer Transcription Factor-1
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POU2AF1 protein, human
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POU2F1 protein, human
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Peptide Fragments
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Recombinant Proteins
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Trans-Activators
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Transcription Factors
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DNA