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Crystal Structure of Trichoplusia ni secreted ferritin
Structural highlights
FunctionFRIL_TRINI Stores iron in a soluble, non-toxic, readily available form. Important for iron homeostasis. Iron is taken up in the ferrous form and deposited as ferric hydroxides after oxidation (By similarity). Ferritin is composed of a heavy (H) chain which is responsible for the oxidation and uptake of ferrous iron, and a light (L) chain which facilitates the nucleation of the ferrihydrite iron core (Probable).[RuleBase:RU361145][1] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedFerritins are iron storage proteins made of 24 subunits forming a hollow spherical shell. Vertebrate ferritins contain varying ratios of heavy (H) and light (L) chains; however, known ferritin structures include only one type of chain and have octahedral symmetry. Here, we report the 1.9A structure of a secreted insect ferritin from Trichoplusia ni, which reveals equal numbers of H and L chains arranged with tetrahedral symmetry. The H/L-chain interface includes complementary features responsible for ordered assembly of the subunits. The H chain contains a ferroxidase active site resembling that of vertebrate H chains with an endogenous, bound iron atom. The L chain lacks the residues that form a putative iron core nucleation site in vertebrate L chains. Instead, a possible nucleation site is observed at the L chain 3-fold pore. The structure also reveals inter- and intrasubunit disulfide bonds, mostly in the extended N-terminal regions unique to insect ferritins. The symmetrical arrangement of H and L chains and the disulfide crosslinks reflect adaptations of insect ferritin to its role as a secreted protein. Crystal structure of a secreted insect ferritin reveals a symmetrical arrangement of heavy and light chains.,Hamburger AE, West AP Jr, Hamburger ZA, Hamburger P, Bjorkman PJ J Mol Biol. 2005 Jun 10;349(3):558-69. Epub 2005 Apr 12. PMID:15896348[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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