Structure of bradavidin-C-terminal residues act as intrinsic ligands

Jenni Leppiniemi, Toni Grönroos, Juha A. E. Määttä, Mark S Johnson, Markku S. Kulomaa, Vesa P. Hytönen, Tomi Airenne*

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

Abstract

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 ∼25 µM 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.
Original languageEnglish
JournalPLOS ONE
Volume7(5)
Issue numbere35962
DOIs
Publication statusPublished - 4 May 2012
MoE publication typeA1 Journal article-refereed

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