| Structural highlights
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 self-assembling protein nanocompartments able to selectively encapsulate dedicated cargo enzymes. Encapsulins are widespread across bacterial and archaeal phyla and are involved in oxidative stress resistance, iron storage, and sulfur metabolism. Encapsulin shells exhibit icosahedral geometry and consist of 60, 180, or 240 identical protein subunits. Cargo encapsulation is mediated by the specific interaction of targeting peptides or domains, found in all cargo proteins, with the interior surface of the encapsulin shell during shell self-assembly. Here, we report the 2.53 A cryo-EM structure of a heterologously produced and highly cargo-loaded T3 encapsulin shell from Myxococcus xanthus and explore the systems' structural heterogeneity. We find that exceedingly high cargo loading results in the formation of substantial amounts of distorted and aberrant shells, likely caused by a combination of unfavorable steric clashes of cargo proteins and shell conformational changes. Based on our cryo-EM structure, we determine and analyze the targeting peptide-shell binding mode. We find that both ionic and hydrophobic interactions mediate targeting peptide binding. Our results will guide future attempts at rationally engineering encapsulins for biomedical and biotechnological applications.
Structure and heterogeneity of a highly cargo-loaded encapsulin shell.,Kwon S, Andreas MP, Giessen TW J Struct Biol. 2023 Aug 30;215(4):108022. doi: 10.1016/j.jsb.2023.108022. PMID:37657675[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
- ↑ Kwon S, Andreas MP, Giessen TW. Structure and heterogeneity of a highly cargo-loaded encapsulin shell. J Struct Biol. 2023 Aug 30;215(4):108022. PMID:37657675 doi:10.1016/j.jsb.2023.108022
|
