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. Author manuscript; available in PMC: 2012 Apr 1.
Published in final edited form as: Biochim Biophys Acta. 2010 Oct 26;1812(4):544–548. doi: 10.1016/j.bbadis.2010.10.010

Figure 1. Ferritin structural disruption and aggregation caused by Mt-FTL subunits.

Figure 1

(a) The structure of the spherical shell is maintained in mutant ferritin as seen in thecrystallographic structures of Wt- and Mt-FTL homopolymers viewed down one of their 4-fold axes. (b) Close up views of the 4-fold pore from the interior of the Wt- and Mt-FTL structures show remarkable disruption in Mt-FTL making the pores unstable and leaky. Note that since the last 26 amino acids of Mt-FTL remained unaccounted for crystallographically, mutant C-termini are substantially longer than represented in (b), and if extended could reach as far as the diameter of the ferritin shell. (c) Iron loading-induced aggregation of Mt-FTL homopolymers is consistent with a model in which iron binds to the unraveled and extended portion of the mutant C-termini on two different ferritin shells bridging them and initiating a gradual accumulation of ferritin and iron into a precipitate. Bridging is not necessarily restricted to C-termini and may become more general, e.g., between a C-terminal group and a surface amino acid which both have affinity for iron. Structures were taken from RCSB (code 2FG8 for Wt-FTL and 3HX2 for Mt-FTL) and the precipitation model was modified from [14].