Background. The chicken genome contains a BBP-A gene showing similar characteristics to avidin family genes. In a previous study we reported that the BBP-A gene may encode a biotin-binding protein due to the high sequence similarity with chicken avidin, especially at regions encoding residues known to be located at the ligand-binding site of avidin. Results. Here, we expand the repertoire of known macromolecular biotin binders by reporting a novel biotin-binding protein A (BBP-A) from chicken. The BBP-A recombinant protein was expressed using two different expression systems and purified with affinity chromatography, biochemically characterized and two X-ray structures were solved - in complex with D-biotin (BTN) and in complex with D-biotin D-sulfoxide (BSO). The BBP-A protein binds free biotin with high, "streptavidin- like" affinity (Kd ∼ 10-13M), which is about 50 times lower than that of chicken avidin. Surprisingly, the affinity of BBP-A for BSO is even higher than the affinity for BTN. Furthermore, the solved structures of the BBP-A - BTN and BBP-A - BSO complexes, which share the fold with the members of the avidin and lipocalin protein families, are extremely similar to each other. Conclusion. BBP-A is an avidin-like protein having a β-barrel fold and high affinity towards BTN. However, BBP-A differs from the other known members of the avidin protein family in thermal stability and immunological properties. BBP-A also has a unique ligand-binding property, the ability to bind BTN and BSO at comparable affinities. BBP-A may have use as a novel material in, e.g. modern bio(nano)technological applications. © 2007 Hytönen et al; licensee BioMed Central Ltd.
CITATION STYLE
Hytönen, V. P., Määttä, J. A. E., Niskanen, E. A., Huuskonen, J., Helttunen, K. J., Halling, K. K., … Airenne, T. T. (2007). Structure and characterization of a novel chicken biotin-binding protein A (BBP-A). BMC Structural Biology, 7. https://doi.org/10.1186/1472-6807-7-8
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