7s2t

From Proteopedia

M. xanthus encapsulin EncA bound to EncB targeting peptide

Structural highlights

7s2t is a 6 chain structure with sequence from Myxococcus xanthus. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
Method:	Electron Microscopy, Resolution 3.45Å
Resources:	FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT

Function

ENCAP_MYXXD Shell component of a type 1, iron-storage encapsulin nanocompartment. Encapsulin nanocompartments are 32 nm in diameter with an iron- and phosphorus-rich core (4Fe:1P) about 24 nm in diameter. Upon expression in E.coli most particles are 32 nm, 20% are 18 nm. The core is filled with an average of 14 dense granules, 5-6 nm in diameter that are not evenly distributed. Each nanocompartment is estimated to hold 30,000-35,000 Fe atoms (PubMed:25024436, PubMed:31194509). The minor proteins EncB, EncC and EncD probably lie against the interior face of the nanocompartment (Probable).^[1] ^[2] ^[3]

Publication Abstract from PubMed

Encapsulins are bacterial organelle-like cages involved in various aspects of metabolism, especially protection from oxidative stress. They can serve as vehicles for a wide range of medical applications. Encapsulin shell proteins are structurally similar to HK97 bacteriophage capsid protein and their function depends on the encapsulated cargos. The Myxococcus xanthus encapsulin system comprises EncA and three cargos: EncB, EncC, and EncD. EncB and EncC are similar to bacterial ferritins that can oxidize Fe(+2) to less toxic Fe(+3). We analyzed EncA, EncB, and EncC by cryo-EM and X-ray crystallography. Cryo-EM shows that EncA cages can have T = 3 and T = 1 symmetry and that EncA T = 1 has a unique protomer arrangement. Also, we define EncB and EncC binding sites on EncA. X-ray crystallography of EncB and EncC reveals conformational changes at the ferroxidase center and additional metal binding sites, suggesting a mechanism for Fe oxidation and storage within the encapsulin shell.

Structural characterization of the Myxococcusxanthus encapsulin and ferritin-like cargo system gives insight into its iron storage mechanism.,Eren E, Wang B, Winkler DC, Watts NR, Steven AC, Wingfield PT Structure. 2022 Feb 2. pii: S0969-2126(22)00008-9. doi:, 10.1016/j.str.2022.01.008. PMID:35150605^[4]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

References

↑ McHugh CA, Fontana J, Nemecek D, Cheng N, Aksyuk AA, Heymann JB, Winkler DC, Lam AS, Wall JS, Steven AC, Hoiczyk E. A virus capsid-like nanocompartment that stores iron and protects bacteria from oxidative stress. EMBO J. 2014 Jul 14. pii: e201488566. PMID:25024436 doi:http://dx.doi.org/10.15252/embj.201488566
↑ Sigmund F, Pettinger S, Kube M, Schneider F, Schifferer M, Schneider S, Efremova MV, Pujol-Martí J, Aichler M, Walch A, Misgeld T, Dietz H, Westmeyer GG. Iron-Sequestering Nanocompartments as Multiplexed Electron Microscopy Gene Reporters. ACS Nano. 2019 Jul 23;13(7):8114-8123. PMID:31194509 doi:10.1021/acsnano.9b03140
↑ McHugh CA, Fontana J, Nemecek D, Cheng N, Aksyuk AA, Heymann JB, Winkler DC, Lam AS, Wall JS, Steven AC, Hoiczyk E. A virus capsid-like nanocompartment that stores iron and protects bacteria from oxidative stress. EMBO J. 2014 Jul 14. pii: e201488566. PMID:25024436 doi:http://dx.doi.org/10.15252/embj.201488566
↑ Eren E, Wang B, Winkler DC, Watts NR, Steven AC, Wingfield PT. Structural characterization of the Myxococcusxanthus encapsulin and ferritin-like cargo system gives insight into its iron storage mechanism. Structure. 2022 Feb 2. pii: S0969-2126(22)00008-9. doi:, 10.1016/j.str.2022.01.008. PMID:35150605 doi:http://dx.doi.org/10.1016/j.str.2022.01.008