4p18 | pdb_00004p18

Crystal Structure of frog M ferritin mutant D80K

spinqualitylabelsall models 4p18, resolution 1.91Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 4p18 is a 24 chain structure with sequence from Lithobates catesbeianus. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: ACT, CL, EDO, SO4 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function FRI2_LITCT Stores iron in a soluble, non-toxic, readily available form. Important for iron homeostasis. Has ferroxidase activity. Iron is taken up in the ferrous form and deposited as ferric hydroxides after oxidation. Publication Abstract from PubMed Functional ferritins are 24-mer nanocages that self-assemble with extended contacts between pairs of 4-helix bundle subunits coupled in an antiparallel fashion along the C2 axes. The largest intersubunit interaction surface in the ferritin nanocage involves helices, but contacts also occur between groups of three residues midway in the long, solvent-exposed L-loops of facing subunits. The anchor points between intersubunit L-loop pairs are the salt bridges between the symmetry-related, conserved residues Asp80 and Lys82. The resulting quaternary structure of the cage is highly soluble and thermostable. Substitution of negatively charged Asp80 with a positively charged Lys in homopolymeric M ferritin introduces electrostatic repulsions that inhibit the oligomerization of the ferritin subunits. D80K ferritin was present in inclusion bodies under standard overexpressing conditions in E. coli, contrasting with the wild type protein. Small amounts of fully functional D80K nanocages formed when expression was slowed. The more positively charged surface results in a different solubility profile and D80K crystallized in a crystal form with a low density packing. The 3D structure of D80K variant is the same as wild type except for the side chain orientations of Lys80 and facing Lys82. When three contiguous Lys groups are introduced in D80KI81K ferritin variant the nanocage assembly is further inhibited leading to lower solubility and reduced thermal stability. Here, we demonstrate that the electrostatic pairing at the center of the L-loops has a specific kinetic role in the self-assembly of ferritin nanocages. Loop Electrostatics Modulates the Intersubunit Interactions in Ferritin.,Bernacchioni C, Ghini V, Pozzi C, Di Pisa F, Theil EC, Turano P ACS Chem Biol. 2014 Aug 29. PMID:25148224 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Ferritin 3D structures

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