PT  - JOURNAL ARTICLE
AU  - Didi He
AU  - Sam Hughes
AU  - Sally Vanden-Hehir
AU  - Atanas Georgiev
AU  - Kirsten Altenbach
AU  - Emma Tarrant
AU  - C. Logan Mackay
AU  - Kevin J. Waldron
AU  - David J. Clarke
AU  - Jon Marles-Wright
TI  - Structural characterization of encapsulated ferritin provides insight into iron storage in bacterial nanocompartments
AID  - 10.1101/063495
DP  - 2016 Jan 01
TA  - bioRxiv
PG  - 063495
4099  - http://biorxiv.org/content/early/2016/07/12/063495.short
4100  - http://biorxiv.org/content/early/2016/07/12/063495.full
AB  - 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 centre 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.