1eum
From Proteopedia
|
CRYSTAL STRUCTURE OF THE E.COLI FERRITIN ECFTNA
Overview
The high-resolution structure of the non-haem ferritin from Escherichia, coli (EcFtnA) is presented together with those of its Fe(3+) and Zn(2+), derivatives, this being the first high-resolution X-ray analysis of the, iron centres in any ferritin.The binding of both metals is accompanied by, small changes in the amino acid ligand positions. Mean Fe(A)(3+)-Fe(B)(3+), and Zn(A)(2+)-Zn(B)(2+) distances are 3.24 A and 3.43 A, respectively. In, both derivatives, metal ions at sites A and B are bridged by a glutamate, side-chain (Glu50) in a syn-syn conformation. The Fe(3+) derivative alone, shows a third metal site (Fe( C)( 3+)) joined to Fe(B)(3+) by a long, anti-anti bidentate bridge through Glu130 (mean Fe(B)(3+)-Fe(C)(3+), distance 5.79 A). The third metal site is unique to the non-haem bacterial, ferritins.The dinuclear site lies at the inner end of a hydrophobic, channel connecting it to the outside surface of the protein shell, which, may provide access for dioxygen and possibly for metal ions shielded by, water. Models representing the possible binding mode of dioxygen to the, dinuclear Fe(3+) pair suggest that a gauche micro-1,2 mode may be, preferred stereochemically.Like those of other ferritins, the 24 subunits, of EcFtnA are folded as four-helix bundles that assemble into hollow, shells and both metals bind at dinuclear centres in the middle of the, bundles. The structural similarity of EcFtnA to the human H chain ferritin, (HuHF) is remarkable (r.m.s. deviation of main-chain atoms 0.66 A) given, the low amino acid sequence identity (22 %). Many of the conserved, residues are clustered at the dinuclear centre but there is very little, conservation of residues making inter-subunit interactions.
About this Structure
1EUM is a Single protein structure of sequence from Escherichia coli. Full crystallographic information is available from OCA.
Reference
The high-resolution X-ray crystallographic structure of the ferritin (EcFtnA) of Escherichia coli; comparison with human H ferritin (HuHF) and the structures of the Fe(3+) and Zn(2+) derivatives., Stillman TJ, Hempstead PD, Artymiuk PJ, Andrews SC, Hudson AJ, Treffry A, Guest JR, Harrison PM, J Mol Biol. 2001 Mar 23;307(2):587-603. PMID:11254384
Page seeded by OCA on Tue Nov 20 14:19:48 2007
