期刊
PROTIST
卷 170, 期 3, 页码 287-313出版社
ELSEVIER GMBH
DOI: 10.1016/j.protis.2019.05.001
关键词
Acidocalcisomes; polyphosphate granules; Chlamydomonas reinhardtii; freeze-fracture; phylogenetic analyses; Asgard archaea
类别
资金
- US Department of Energy
- International Center for Energy, Environment and Sustainability
- Natural Sciences and Engineering Research Council (NSERC) [418471-12]
- Korea CCS R&D Center (KCRC), Korean Ministry of Science [2016M1A8A1925345]
- Simons Foundation [382790]
- National Research Foundation of Korea [2016M1A8A1925345] Funding Source: Korea Institute of Science & Technology Information (KISTI), National Science & Technology Information Service (NTIS)
Acidocalcisomes are membrane-enclosed organelles with acidic lumens that accumulate polyphosphate, often in granular form, and sequester calcium and metals. They carry a transmembrane polyphosphate polymerase and two classes of proton pumps:H+-pyrophosphatases (H+-PPases) and Vtype ATPases. This report describes acidocalcisomes that were snap-frozen in living cells, primarily the green alga Chlamydomonas reinhardtii, and then fractured and etched (QFDEEM). Polyphosphate granules prove to be uncommon in log-phase C. reinhardtii cells and abundant in stressed cells, where they are also found within autophagy-related vacuoles. Their E (ectoplasmic) fracture face adopts a unique rugose morphology with etching, and displays similar to 14 nm globular domains in broken cell preparations. Using etched membrane morphology as a guide, acidocalcisomes were identified during assembly in the trans-Golgi and were recognized in QFDEEM replicas of 18 additional algae and protists. Phylogenetic analysis documents that the eukaryotic gene encoding the signature acidocalcisomal H+-PPase pump has homologues in three widespread eukaryotic clades and has been lost in opisthokonts and Amoebozoa. The eukaryotic clades are related to three functionally diverged prokaryotic PPase pumps, one of which transports Na+. Our data indicate that the Last Eukaryotic Common Ancestor (LECA) encoded two bacteria-derived pumps and one Asgard-archaea-derived pump. (C) 2019 Elsevier GmbH. All rights reserved.
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