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Crystal structure of the Bach1 BTB domain and its regulation of homodimerization
Author(s) -
Ito Nobutoshi,
WatanabeMatsui Miki,
Igarashi Kazuhiko,
Murayama Kazutaka
Publication year - 2009
Publication title -
genes to cells
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.912
H-Index - 115
eISSN - 1365-2443
pISSN - 1356-9597
DOI - 10.1111/j.1365-2443.2008.01259.x
Subject(s) - monomer , domain (mathematical analysis) , biophysics , protein structure , hydrogen bond , biology , covalent bond , crystallography , biochemistry , chemistry , molecule , mathematical analysis , mathematics , organic chemistry , polymer
The BTB/POZ domain is known as a protein–protein interaction motif that mediates homodimer and higher order self‐associations. Proteins containing the BTB domain exist throughout eukaryotes; however, there is little information about the mechanism that determines the oligomeric state of the BTB domain. To address this question, we have determined the X‐ray structure of the mouse Bach1 BTB domain. The present structure is similar to the previously determined BTB domain folds, including the human Bach1 BTB domain; however, distinct structural features are present, such as a novel homodimer interaction surface. The homodimer formation was found to involve a novel hydrogen bond network and interactions between hydrophobic surfaces of the kinked N‐terminus (N‐hook) and the partner's C‐terminal residues. The deletion of the N‐hook resulted in the conversion of the homodimer into a monomer in solution, indicating that the N‐hook promotes the homodimerization of the mBach1 BTB domain. We have also found that the BTB domain of Bach2, a protein highly related to Bach1, is present as a monomer due to a short peptide insertion at the N‐hook. These results represent the first example of the key modulatory element of BTB domain homodimerization.