4PT2

Myxococcus xanthus encapsulin protein (EncA)

Summary for 4PT2

• Entry DOI: 10.2210/pdb4pt2/pdb
• EMDB information: 5917
• Descriptor: Encapsulin protein (1 entity in total)
• Functional Keywords: hk97 fold, shell protein, virus like particle
• Biological source: Myxococcus xanthus
• Total number of polymer chains: 3
• Total formula weight: 95075.93

Authors

Fontana, J.,Aksyuk, A.A.,Steven, A.C.,Hoiczyk, E. (deposition date: 2014-03-10, release date: 2014-07-30, Last modification date: 2024-02-28)

Primary citation

McHugh, C.A.,Fontana, J.,Nemecek, D.,Cheng, N.,Aksyuk, A.A.,Heymann, J.B.,Winkler, D.C.,Lam, A.S.,Wall, J.S.,Steven, A.C.,Hoiczyk, E.
A virus capsid-like nanocompartment that stores iron and protects bacteria from oxidative stress.
Embo J., 33:1896-1911, 2014

PubMed Abstract: 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 nanocompartment from Myxococcus xanthus, which consists of a shell protein (EncA, 32.5 kDa) and three internal proteins (EncB, 17 kDa; EncC, 13 kDa; EncD, 11 kDa). Using cryo-electron microscopy, we determined that EncA self-assembles into an icosahedral shell 32 nm in diameter (26 nm internal diameter), built from 180 subunits with the fold first observed in bacteriophage HK97 capsid. The internal proteins, of which EncB and EncC have ferritin-like domains, attach to its inner surface. Native nanocompartments have dense iron-rich cores. Functionally, they resemble ferritins, cage-like iron storage proteins, but with a massively greater capacity (~30,000 iron atoms versus ~3,000 in ferritin). Physiological data reveal that few nanocompartments are assembled during vegetative growth, but they increase fivefold upon starvation, protecting cells from oxidative stress through iron sequestration.

PubMed: 25024436
DOI: 10.15252/embj.201488566

Experimental method

ELECTRON MICROSCOPY (4.6 Å)