Structure of human ferritin L chain.
Ferritin is the major iron-storage protein present in all cells. It generally contains 24 subunits, with different ratios of heavy chain (H) to light chain (L), in the shape of a hollow sphere hosting up to 4500 ferric Fe atoms inside. H-rich ferritins catalyse the oxidation of iron(II), while L-rich ferritins promote the nucleation and storage of iron(III). Several X-ray structures have been determined, including those of L-chain ferritins from horse spleen (HoSF), recombinant L-chain ferritins from horse (HoLF), mouse (MoLF) and bullfrog (BfLF) as well as recombinant human H-chain ferritin (HuHF). Here, structures have been determined of two crystal forms of recombinant human L-chain ferritin (HuLF) obtained from native and perdeuterated proteins. The structures show a cluster of acidic residues at the ferrihydrite nucleation site and at the iron channel along the threefold axis. An ordered Cd2+ structure is observed within the iron channel, offering further insight into the route and mechanism of iron transport into the capsid. The loop between helices D and E, which is disordered in many other L-chain structures, is clearly visible in these two structures. The crystals generated from perdeuterated HuLF will be used for neutron diffraction studies.
Wang
Zhongmin
Z
New Century Pharmaceuticals Inc., 895 Martin Road, Huntsville, Alabama 35824, USA.
Li
Chester
C
Ellenburg
Melanie
M
Soistman
Elizabeth
E
Ruble
John
J
Wright
Brenda
B
Ho
Joseph X
JX
Carter
Daniel C
DC
D000596:Amino Acids / Q000737:chemistry / Q000378:metabolism; D000818:Animals; D001665:Binding Sites; D002104:Cadmium / Q000737:chemistry / Q000378:metabolism; D018360:Crystallography, X-Ray; D005293:Ferritins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D005296:Ferrous Compounds / Q000737:chemistry / Q000378:metabolism; D006736:Horses / Q000378:metabolism; D006801:Humans; D007501:Iron / Q000737:chemistry / Q000378:metabolism; D008958:Models, Molecular; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D021122:Protein Subunits / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D014867:Water / Q000737:chemistry
D000596:Amino Acids; D005296:Ferrous Compounds; D021122:Protein Subunits; D011994:Recombinant Proteins; D002104:Cadmium; D014867:Water; D005293:Ferritins; D007501:Iron