Open AccessA novel mode of ferric ion coordination by the periplasmic ferric ion‐binding subunit FbpA of an ABC‐type iron transporter from Thermus thermophilus HB8
Author(s) -
Wang Shipeng,
Ogata Misaki,
Horita Shoichiro,
Ohtsuka Jun,
Nagata Koji,
Tanokura Masaru
Publication year - 2014
Publication title -
acta crystallographica section d
Language(s) - English
Resource type - Journals
ISSN - 1399-0047
DOI - 10.1107/s1399004713026333
Subject(s) - thermus thermophilus , periplasmic space , ferric , chemistry , crystallography , inorganic chemistry , biochemistry , escherichia coli , gene
Crystal structures of FbpA, the periplasmic ferric ion‐binding protein of an iron‐uptake ABC transporter, from Thermus thermophilus HB8 (TtFbpA) have been solved in apo and ferric ion‐bound forms at 1.8 and 1.7 Å resolution, respectively. The latter crystal structure shows that the bound ferric ion forms a novel six‐coordinated complex with three tyrosine side chains, two bicarbonates and a water molecule in the metal‐binding site. The results of gel‐filtration chromatography and dynamic light scattering show that TtFbpA exists as a monomer in solution regardless of ferric ion binding and that TtFbpA adopts a more compact conformation in the ferric ion‐bound state than in the apo state in solution.