1NFT

OVOTRANSFERRIN, N-TERMINAL LOBE, IRON LOADED OPEN FORM

Summary for 1NFT

• Entry DOI: 10.2210/pdb1nft/pdb
• Descriptor: PROTEIN (OVOTRANSFERRIN), SULFATE ION, FE (III) ION, ... (5 entities in total)
• Functional Keywords: transferrin, ovotransferrin, iron binding protein, transport protein
• Biological source: Gallus gallus (chicken)
• Cellular location: Secreted: P02789
• Total number of polymer chains: 1
• Total formula weight: 36784.15

Authors

Mizutani, K.,Yamashita, H.,Kurokawa, H.,Mikami, B.,Hirose, M. (deposition date: 1999-01-07, release date: 1999-01-13, Last modification date: 2024-10-16)

Primary citation

Mizutani, K.,Yamashita, H.,Kurokawa, H.,Mikami, B.,Hirose, M.
Alternative structural state of transferrin. The crystallographic analysis of iron-loaded but domain-opened ovotransferrin N-lobe.
J.Biol.Chem., 274:10190-10194, 1999

PubMed Abstract: Transferrins bind Fe3+ very tightly in a closed interdomain cleft by the coordination of four protein ligands (Asp60, Tyr92, Tyr191, and His250 in ovotransferrin N-lobe) and of a synergistic anion, physiologically bidentate CO32-. Upon Fe3+ uptake, transferrins undergo a large scale conformational transition: the apo structure with an opening of the interdomain cleft is transformed into the closed holo structure, implying initial Fe3+ binding in the open form. To solve the Fe3+-loaded, domain-opened structure, an ovotransferrin N-lobe crystal that had been grown as the apo form was soaked with Fe3+-nitrilotriacetate, and its structure was solved at 2.1 A resolution. The Fe3+-soaked form showed almost exactly the same overall open structure as the iron-free apo form. The electron density map unequivocally proved the presence of an iron atom with the coordination by the two protein ligands of Tyr92-OH and Tyr191-OH. Other Fe3+ coordination sites are occupied by a nitrilotriacetate anion, which is stabilized through the hydrogen bonds with the peptide NH groups of Ser122, Ala123, and Gly124 and a side chain group of Thr117. There is, however, no clear interaction between the nitrilotriacetate anion and the synergistic anion binding site, Arg121.

PubMed: 10187803
DOI: 10.1074/jbc.274.15.10190

Experimental method

X-RAY DIFFRACTION (2.1 Å)