2020 Fiscal Year Annual Research Report
Eukaryotic-like proteins from Asgard archaea
| Project/Area Number |
20H00476
|
|---|
| Research Institution | Okayama University |
|---|
Principal Investigator |
ROBINSON ROBERT 岡山大学, 異分野基礎科学研究所, 特任教授 (60814118)
|
|---|
| Project Period (FY) |
2020-04-01 – 2025-03-31
|
| Keywords | Asgard / Evolution / Actin / Gelsolin / Eukaryogenesis |
|---|
| Outline of Annual Research Achievements |
The origin of the eukaryotic cell is controversial. Metagenomics sequencing has revealed that Asgard archaea genomes contain potential homologs to eukaryotic genes. Several of these gene products are involved in forming the cytoskeleton, a hallmark of eukaryotic cells. Eukaryotic gelsolin superfamily proteins generally comprise three or more related domains. Here we characterize single- and double-domain gelsolins from Thorarchaeota (Thor). Similar domain architectures are present in Heimdall-, Loki-, and Odinarchaeota. Thor gelsolins are functional in regulating rabbit actin in in vitro assays, showing a range of activities including actin filament severing and bundling. These gelsolins bind to the eukaryotic gelsolin/cofilin-binding site on actin. Two-domain, but not one-domain, gelsolins are calcium regulated. Thor gelsolins appear to have the characteristics and structure consistent with primitive gelsolins/cofilins, suggesting that these single- and double-domain gelsolins are a record of a nascent pre-eukaryotic actin-regulation machinery.
|
| Current Status of Research Progress |
Current Status of Research Progress
1: Research has progressed more than it was originally planned.
Reason
We have published one paper in PNAS that details the interactions of Asgard (Thor) one and two domain gelsolins with eukaryotic actin. We are now writing a second manuscript that expands the characterization of the Asgard gelsolins to Loki and Heimdall. These proteins show surprising variety indicating diversification of the actin cytoskeleton after the last common ancestor of Asgard archaea. We have also made significant progress in analyzing Asgard small GTPases, Roadblocks and TRAPP proteins. These structures indicate how membrane trafficking has evolved.
|
| Strategy for Future Research Activity |
We will further investigate the potential cytoskeletal proteins and membrane regulating proteins encoded in the Asgard metagenomics data: the cytoskeletal proteins tubulins, actins, and proteins involved in trafficking, N-glycosylation, ESCRT complexes, ubiquitination system, and small GTPases. We will use structural biology, biochemistry and cell biology to provide insight as to whether Asgard can be considered as model organisms for the archaea-to-eukaryotic transition. One particular focus will be on the Asgard tubulin. We will determine the structures of Odin tubulin, to assess how far along the evolutionary transition from the prokaryotic cell division protein FtsZ to the eukaryotic microtubule this Asgard tubulin has progressed.
|
