Reposted by James Lingford
Excited to share our manuscript “A geothermal amoeba sets a new upper temperature limit for eukaryotes” is out in Cell! This work, led by @oliverio.bsky.social & @hbrappap.bsky.social, introduces I. cascadensis, which divides at 63C, beating the prior eukaryotic limit of 60C. doi.org/10.1016/j.ce...
cell.com
A geothermal amoeba sets a new upper temperature limit for eukaryotes
The amoeba Incendiamoeba cascadensis demonstrates that eukaryotic life can withstand
temperatures beyond what was thought possible and sheds light on molecular strategies
for survival in extreme heat.
![Supplementary Fig. 29 | CombFold models of putative electron bifurcating complexes. a. The putative Nuo(EFG)
2-Mvh(ADG)
2-Etf(AB)
2-Hdr
2 electron bifurcating complex found in Hodarchaeales MAG GCA_016840025. Top: individual AF2 models of the NuoEFG, MvhADG, and EtfAB-Hdr modules forming part of the total complex. Bottom: the CombFold assembled model shown from three different views. Subunits are colored according to the labelling shown in the top panel. b. The putative Nuo(EFG)4- Frh(AG)4 electron bifurcating complex found in Hodarchaeales MAG GCA_020353515. Top: individual AF2 models of the NuoEFG and FrhAG modules forming part of the total complex. Bottom: the CombFold assembled model shown from three different views. Subunits are colored according to the labelling shown in the top panel. Frh: F
420-reducing hydrogenase (a [NiFe]-hydrogenase). Mvh: Methyl viologen-reducing hydrogenase (a [NiFe]-hydrogenase). Etf: electron transferring flavoprotein. Hdr: heterodisulfide reductase.](https://cdn.bsky.app/img/feed_thumbnail/plain/did:plc:arnopirhmzvadspoff2l3235/bafkreibnmuyqu3rz3hii36cgqlhdkczyqrjw4lq3ac32ldef7ki2qdufqu)
![Supplementary Fig. 44 | AlphaFold2 monomer models of [NiFe]-hydrogenase large subunits Group 4. Maximum likelihood phylogeny was inferred from a supermatrix of 3007 sequences and 440 amino acid positions (from 2216 initial positions), displaying the diversity of Asgard archaea hydrogenases collapsed to highlight [NiFe]-Groups 4 (blue) identified by the external ring. The tree was generated using IQ-TREE v2.0.7 (1000 ultrafast bootstrap replicates and calculation of 1000 SH-alRT) with Q.pfam+C50+R8 best-fit model chosen according to Bayesian Information Criterion (BIC). Previously identified subgroups are labeled in black. The novel hydrogenase groups identified and named in this study are distinguished by branch and label color-coded according to the group. The black check marks highlight the 14 large catalytic subunits chosen for monomer modeling for subgroups 4j, 4l, 4p, and 4q. Support values are shown when ultrafast (UF) bootstrap support is greater than or equal to 95 and SH-aLRT support is greater than or equal to 80. Individual monomers colored by the predicted local distance difference test (pLDDT) scores. Only top ranked AF2 models are shown. The phylogeny was visualized with iTOL and midpoint rooted between the known hydrogenase clades and pruned to show each group, separately.](https://cdn.bsky.app/img/feed_thumbnail/plain/did:plc:arnopirhmzvadspoff2l3235/bafkreih456b7vlip6725leektaaiaj6siku4c324dqvjrs3q2rxeyw7xem)
![Supplementary Fig. 43 | AlphaFold2 monomer models of [NiFe]-hydrogenase large subunits Group 3. Maximum likelihood phylogeny was inferred from a supermatrix of 3007 sequences and 440 amino acid positions (from 2216 initial positions), displaying the diversity of Asgard archaea hydrogenases collapsed to highlight [NiFe]-Groups 3 (orange) identified by the external ring. The tree was generated using IQ- TREE v2.0.7 (1000 ultrafast bootstrap replicates and calculation of 1000 SH-alRT) with Q.pfam+C50+R8 best-fit model chosen according to Bayesian Information Criterion (BIC). Previously identified subgroups are labeled in black. The novel hydrogenase groups identified and named in this study are distinguished by branch and label color-coded according to the group. The black check marks highlight the 12 large catalytic subunits chosen for monomer modeling for subgroups 3a, 3b, 3e, 3f, and 3k. Support values are shown when ultrafast (UF) bootstrap support is greater than or equal to 95 and SH-aLRT support is greater than or equal to 80. Individual monomers colored by the predicted local distance difference test (pLDDT) scores. Only top ranked AF2 models are shown. The phylogeny was visualized with iTOL and midpoint rooted between the known hydrogenase clades and pruned to show each group, separately.](https://cdn.bsky.app/img/feed_thumbnail/plain/did:plc:arnopirhmzvadspoff2l3235/bafkreigfwqrgcy4ek2sxzqybfdlh2bce6ldgkfeftpduocn6nnvs2v2ppm)
![Fig. 3 | Asgard archaea produce structurally diverse respiratory complexes. a, Phylogeny of hydrogen-evolving Group 4 [NiFe]-hydrogenases, displaying the novel subclades 4j–r with blue branches and the Asgard lineage in the second ring. AlphaFold2 Multimer structures outline the phylogeny, indicating a transition from an MBH-like to a Complex I-like structure. Asgardarchaeia structures from 4k and 4l form an MBH-like complex represented by cryogenic electron microscopy(cryo-EM)-validated Pyrococcus furiosus MBH (Protein Data Bank (PDB): 6CFW) and membrane-bound sulfane sulfur reductase (MBS) (PDB: 6U8Y) structures. The other complexes, 4m, 4p and 4q, have structures that are more similar to the E. coli Complex I (PDB: 7P62).](https://cdn.bsky.app/img/feed_thumbnail/plain/did:plc:arnopirhmzvadspoff2l3235/bafkreibpfflmyih27altnv5hmqxfsylh3cwsjx5sw5as3cq5sxd2f4laiq)
