6NJ8 image
Entry Detail
PDB ID:
6NJ8
EMDB ID:
Keywords:
Title:
Encapsulin iron storage compartment from Quasibacillus thermotolerans
Biological Source:
Host Organism:
PDB Version:
Deposition Date:
2019-01-02
Release Date:
2019-08-07
Method Details:
Experimental Method:
Resolution:
3.85 Å
Aggregation State:
PARTICLE
Reconstruction Method:
SINGLE PARTICLE
Macromolecular Entities
Polymer Type:polypeptide(L)
Description:Encapsulating protein for a DyP-type peroxidase
Chain IDs:A, B, C, D
Chain Length:282
Number of Molecules:4
Biological Source:Quasibacillus thermotolerans
Polymer Type:polypeptide(L)
Description:targeting peptide
Chain IDs:E, F, G
Chain Length:7
Number of Molecules:3
Biological Source:Bacillus thermotolerans
Ligand Molecules
Primary Citation
Large protein organelles form a new iron sequestration system with high storage capacity.
Elife 8 ? ? (2019)
PMID: 31282860 DOI: 10.7554/eLife.46070

Abstact

Iron storage proteins are essential for cellular iron homeostasis and redox balance. Ferritin proteins are the major storage units for bioavailable forms of iron. Some organisms lack ferritins, and it is not known how they store iron. Encapsulins, a class of protein-based organelles, have recently been implicated in microbial iron and redox metabolism. Here, we report the structural and mechanistic characterization of a 42 nm two-component encapsulin-based iron storage compartment from Quasibacillus thermotolerans. Using cryo-electron microscopy and x-ray crystallography, we reveal the assembly principles of a thermostable T = 4 shell topology and its catalytic ferroxidase cargo and show interactions underlying cargo-shell co-assembly. This compartment has an exceptionally large iron storage capacity storing over 23,000 iron atoms. Our results reveal a new approach for survival in diverse habitats with limited or fluctuating iron availability via an iron storage system able to store 10 to 20 times more iron than ferritin.

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Primary Citation of related structures