PT  - JOURNAL ARTICLE
AU  - Tobias W. Giessen
AU  - Pamela A. Silver
TI  - Microbes use encapsulin protein organelles to sequester toxic reactions
AID  - 10.1101/085266
DP  - 2016 Jan 01
TA  - bioRxiv
PG  - 085266
4099  - http://biorxiv.org/content/early/2016/11/02/085266.short
4100  - http://biorxiv.org/content/early/2016/11/02/085266.full
AB  - Cells organize and regulate their metabolism via membrane-or protein-bound organelles. In this way, incompatible processes can be spatially separated and controlled. In prokaryotes, protein-based compartments are used to sequester harmful reactions and store useful compounds. These protein compartments play key roles in various metabolic and ecological processes ranging from iron homeostasis to carbon fixation. We identified more than 900 proteinaceous encapsulin nanocompartment systems in bacterial and archaeal genomes. Encapsulins can be found in 15 bacterial and 2 archaeal phyla. Our analysis reveals 1 new capsid type and 9 previously unknown cargo proteins targeted to the interior of encapsulins. We experimentally characterize 3 newly identified encapsulin systems and illustrate their involvement in iron mineralization, oxidative and nitrosative stress resistance and anaerobic ammonium oxidation, a process responsible for 30% of the N lost from the oceans. We propose that encapsulins represent a widespread strategy for toxic reaction sequestration in prokaryotes.