Department of Systems Biology, Harvard Medical School, Boston, Massachusetts 02115, USA.
Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, Massachusetts 02115, USA.
Nat Microbiol. 2017 Mar 6;2:17029. doi: 10.1038/nmicrobiol.2017.29.
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. One of the newest types of protein organelle are encapsulin nanocompartments. They are able to encapsulate specific protein cargo and are proposed to be involved in redox-related processes. We identified more than 900 putative encapsulin systems in bacterial and archaeal genomes. Encapsulins can be found in fifteen bacterial and two archaeal phyla. Our analysis reveals one new capsid type and nine previously unknown cargo proteins targeted to the interior of encapsulins. We experimentally characterize three newly identified encapsulin systems and illustrate their probable involvement in iron mineralization, oxidative and nitrosative stress resistance and anaerobic ammonium oxidation, a process responsible for 30% of the nitrogen lost from the oceans.
细胞通过膜结合或蛋白结合的细胞器来组织和调节其代谢。通过这种方式，可以将不相容的过程在空间上分隔开并加以控制。在原核生物中，基于蛋白质的隔室被用来隔离有害反应并储存有用的化合物。这些蛋白隔室在各种代谢和生态过程中发挥着关键作用，从铁稳态到碳固定。最新的蛋白质细胞器之一是包裹体纳米隔室。它们能够包裹特定的蛋白质货物，并被认为参与与氧化还原相关的过程。我们在细菌和古菌基因组中鉴定了超过 900 个假定的包裹体系统。包裹体可以在十五个细菌和两个古菌门中找到。我们的分析揭示了一种新的衣壳类型和九个以前未知的靶向包裹体内腔的货物蛋白。我们通过实验表征了三个新鉴定的包裹体系统，并说明了它们可能参与铁的矿化、氧化和硝化应激抗性以及厌氧氨氧化，这一过程负责海洋中 30%的氮损失。
