8rvj

Structural highlights

Function

ENCAP_BACTR Shell component of a type 1 encapsulin nanocompartment. Assembles into proteinaceous icosahedral shells 42-43 nm in diameter with an iron- and phosphorus-rich core (1Fe:1.1P) which can store over 23,000-35,000 iron atoms (with a calculated maximum of 83,000 Fe). There are 2 types of negatively charged open pores in the cryo-electron structure; a 3-fold pore where 3 hexamers meet with a minimal size of 7.2 Angstroms and a 5-fold pore where pentamers meet with a minimal size of 2.3 Angstroms. The 2-fold pore seen in other encapsulin nanocompartments is closed. Empty compartments can be generated in E.coli (PubMed:28263314, PubMed:31282860, PubMed:31194509). Both types of pore have extra density in their centers in the structure (PubMed:31282860). 2 different cargo proteins have been identified (IMEF and Fer); when both are expressed in E.coli with the shell protein only IMEF is detected within the nanocompartment. E.coli expressing all 3 genes stores the largest amount of iron and is protected from Fe/H2O2-induced oxidative stress (PubMed:28263314). Part of the iron-mineralizing encapsulin-associated Firmicute (IMEF) system (Probable).^{[1] [2] [3] [4]}

References

1. ↑ Giessen TW, Silver PA. Widespread distribution of encapsulin nanocompartments reveals functional diversity. Nat Microbiol. 2017 Mar 6;2:17029. PMID:28263314 doi:10.1038/nmicrobiol.2017.29
2. ↑ 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
3. ↑ Giessen TW, Orlando BJ, Verdegaal AA, Chambers MG, Gardener J, Bell DC, Birrane G, Liao M, Silver PA. Large protein organelles form a new iron sequestration system with high storage capacity. Elife. 2019 Jul 8;8. pii: 46070. doi: 10.7554/eLife.46070. PMID:31282860 doi:http://dx.doi.org/10.7554/eLife.46070
4. ↑ Giessen TW, Silver PA. Widespread distribution of encapsulin nanocompartments reveals functional diversity. Nat Microbiol. 2017 Mar 6;2:17029. PMID:28263314 doi:10.1038/nmicrobiol.2017.29