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CRYSTAL STRUCTURE OF A TERNARY COMPLEX CONTAINING AN OCA-B PEPTIDE, THE OCT-1 POU DOMAIN, AND AN OCTAMER ELEMENT
[OBF1_HUMAN] Note=A chromosomal aberration involving POU2AF1/OBF1 may be a cause of a form of B-cell leukemia. Translocation t(3;11)(q27;q23) with BCL6.
[OBF1_HUMAN] Transcriptional coactivator that specifically associates with either OCT1 or OCT2. It boosts the OCT1 mediated promoter activity and to a lesser extent, that of OCT2. It has no intrinsic DNA-binding activity. It recognizes the POU domains of OCT1 and OCT2. It is essential for the response of B-cells to antigens and required for the formation of germinal centers. [PO2F1_HUMAN] Transcription factor that binds to the octamer motif (5'-ATTTGCAT-3') and activates the promoters of the genes for some small nuclear RNAs (snRNA) and of genes such as those for histone H2B and immunoglobulins. Modulates transcription transactivation by NR3C1, AR and PGR (By similarity). In case of human herpes simplex virus (HSV) infection, POU2F1 forms a multiprotein-DNA complex with the viral transactivator protein VP16 and HCFC1 thereby enabling the transcription of the viral immediate early genes.
Publication Abstract from PubMed
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.
Crystal structure of an OCA-B peptide bound to an Oct-1 POU domain/octamer DNA complex: specific recognition of a protein-DNA interface.,Chasman D, Cepek K, Sharp PA, Pabo CO Genes Dev. 1999 Oct 15;13(20):2650-7. PMID:10541551
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.