Living cells compartmentalize materials and enzymatic reactions to increase metabolic efficiency. While eukaryotes use membrane-bound organelles, bacteria and archaea rely primarily on protein-bound nanocompartments. Encapsulins constitute a class of nanocompartments widespread in bacteria and archaea whose functions have hitherto been unclear. Here, we characterize the encapsulin nanocompartme...

Ferritin concentrates iron as a hydrous ferric oxide in a protein cavity (8 nm in diameter) by using eight pores along the threefold symmetry axes of the octahedral supramolecular structure. The role of ligand exchange in the entry of Fe(II) hexahydrate into ferritin protein has been studied with [Cr(TREN)(H2O)(OH)] [TREN N(CH2CH2NH2)3], a model for Fe(H2O)6 with only two exchangeable ligands. ...

Iron is the most abundant transition metal in the earth's crust. It cycles easily between ferric (oxidized; Fe(III)) and ferrous (reduced; Fe(II)) and readily forms complexes with oxygen, making this metal a central player in respiration and related redox processes. However, 'loose' iron, not within heme or iron-sulfur cluster proteins, can be destructively redox-active, causing damage to almos...

We describe a strategy for the creation of recombinant ferritin heteropolymers which mimic the natural heterogeneity of this protein. This method entailed the co-expression of cDNA for both ferritin H and ferritin L subunits in a single bacterium using either a bicistronic vector, in which both cDNAs were expressed from the vector, or a dual vector expression strategy, in which each subunit was...

Structures of core nanocrystals of physiological (horse spleen, human liver, and brain) and pathological human brain of patients with progressive supranuclear palsy (PSP) and Alzheimer's disease (AD) ferritin molecules were determined using electron nanodiffraction and high-resolution transmission electron microscopy. The poly-phasic structure of the ferritin cores is confirmed. There are signi...

Mitochondrial function depends on iron-containing enzymes and proteins, whose maturation requires available iron for biosynthesis of iron-sulfur clusters and heme. Little is known about how mitochondrial iron homeostasis is maintained, although the recent discovery of a mitochondrial ferritin in mammals and plants has uncovered a potential key player in the process. Here, we show that Drosophil...

BFR (bacterioferritin) is an iron storage and detoxification protein that differs from other ferritins by its ability to bind haem cofactors. Haem bound to BFR is believed to be involved in iron release and was previously thought not to play a role in iron core formation. Investigation of the effect of bound haem on formation of the iron core has been enabled in the present work by development ...

PURPOSE The body concentration of iron is regulated by a fine equilibrium between absorption and losses of iron. Iron can be absorbed from diet as inorganic iron or as heme. Hemopexin is an acute phase protein that limits iron access to microorganisms. Moreover, it is the plasma protein with the highest binding affinity for heme and thus it mediates heme-iron recycling. Considering its involvem...

The study of tissue-derived Mycobacterium leprae provides insights to the immunopathology of leprosy and helps identify broad molecular features necessary for mycobacterial parasitism. A major membrane protein (MMP-II) of in vivo-derived M. leprae previously recognized (Hunter, S.W., B. Rivoire, V. Mehra, B.R. Bloom, and P.J. Brennan. 1990. J. Biol. Chem. 265:14065) was purified from extracts o...

Hepatic iron overload causes lipocyte activation with resultant fibrogenesis. This study examines whether rat lipocytes express ferritin receptors, which could be involved in paracellular iron movement and in cellular regulation. Lipocytes from normal rat liver were cultured on plastic and incubated with 125I-labeled rat liver ferritin (RLF) +/- a 100-fold excess of either unlabeled RLF or huma...