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Bradavidin is a homotetrameric biotin-binding protein from Bradyrhizobium japonicum, a nitrogen fixing and root nodule-forming symbiotic bacterium of the soybean. Wild-type (wt) bradavidin has 138 amino acid residues, whereas the C-terminally truncated core-bradavidin has only 118 residues. We have solved the X-ray structure of wt bradavidin and found that the C-terminal amino acids of each subunit were uniquely bound to the biotin-binding pocket of an adjacent subunit. The biotin-binding pocket occupying peptide (SEKLSNTK) was named "Brad-tag" and it serves as an intrinsic stabilizing ligand in wt bradavidin. The binding of Brad-tag to core-bradavidin was analysed by isothermal titration calorimetry and a binding affinity of approximately 25 microM was measured. In order to study the potential of Brad-tag, a green fluorescent protein tagged with Brad-tag was prepared and successfully concentrated from a bacterial cell lysate using core-bradavidin-functionalized Sepharose resin.
Structure of bradavidin - C-terminal residues act as intrinsic ligands.,Leppiniemi J, Gronroos T, Maatta JA, Johnson MS, Kulomaa MS, Hytonen VP, Airenne TT PLoS One. 2012;7(5):e35962. Epub 2012 May 4. PMID:22574129[1]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
↑ Leppiniemi J, Gronroos T, Maatta JA, Johnson MS, Kulomaa MS, Hytonen VP, Airenne TT. Structure of bradavidin - C-terminal residues act as intrinsic ligands. PLoS One. 2012;7(5):e35962. Epub 2012 May 4. PMID:22574129 doi:10.1371/journal.pone.0035962
