Structural characterization of encapsulated ferritin provides insight into iron storage in bacterial nanocompartments
نویسندگان
چکیده
Ferritins are ubiquitous proteins that oxidise and store iron within a protein shell to protect cells from oxidative damage. We have characterized the structure and function of a new member of the ferritin superfamily that is sequestered within an encapsulin capsid. We show that this encapsulated ferritin (EncFtn) has two main alpha helices, which assemble in a metal dependent manner to form a ferroxidase center at a dimer interface. EncFtn adopts an open decameric structure that is topologically distinct from other ferritins. While EncFtn acts as a ferroxidase, it cannot mineralize iron. Conversely, the encapsulin shell associates with iron, but is not enzymatically active, and we demonstrate that EncFtn must be housed within the encapsulin for iron storage. This encapsulin nanocompartment is widely distributed in bacteria and archaea and represents a distinct class of iron storage system, where the oxidation and mineralization of iron are distributed between two proteins.
منابع مشابه
A virus capsid-like nanocompartment that stores iron and protects bacteria from oxidative stress.
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...
متن کاملPhage Capsid-like Structure of Myxococcus xanthus Encapsulin, a Protein Shell That Stores Iron
Iron is both an essential cofactor of many enzymes and a producer of highly reactive hydroxyl radicals that can cause cellular damage. To regulate the supply of intracellular iron, cells have developed protein-based organelles, like ferritins, that act as iron storage containers. Myxococcus xanthus, a soil-dwelling gram-negative myxobacterium, produces another type of protein-based organelle th...
متن کاملHomeostatic mechanisms for iron storage revealed by genetic manipulations and live imaging of Drosophila ferritin.
Ferritin is a symmetric, 24-subunit iron-storage complex assembled of H and L chains. It is found in bacteria, plants, and animals and in two classes of mutations in the human L-chain gene, resulting in hereditary hyperferritinemia cataract syndrome or in neuroferritinopathy. Here, we examined systemic and cellular ferritin regulation and trafficking in the model organism Drosophila melanogaste...
متن کاملMR characterization of hepatic storage iron in transfusional iron overload.
PURPOSE To quantify the two principal forms of hepatic storage iron, diffuse, soluble iron (primarily ferritin), and aggregated, insoluble iron (primarily hemosiderin) using a new MRI method in patients with transfusional iron overload. MATERIALS AND METHODS Six healthy volunteers and 20 patients with transfusion-dependent thalassemia syndromes and iron overload were examined. Ferritin- and h...
متن کاملEnhanced iron removal from liver parenchymal cells in experimental iron overload: liposome encapsulation of HBED and phenobarbital administration.
The effectiveness of N,N'-bis[2-hydroxybenzyl]-ethylene-diamine-N,N'-diacetic acid (HBED) in removing radioiron introduced into the parenchymal cells of mouse liver as 59Fe-ferritin has been investigated. The effectiveness of HBED, an iron chelator of low water solubility, has also been compared with that of desferrioxamine (DF), an iron chelator of high water solubility and currently in clinic...
متن کامل