Structure of Archaea What makes them so unique compared to bacteria and eukaryotes? C.M. van Gorkum; Microbiology of Man, ...
Overview <ul><li>Introduction </li></ul><ul><li>Archaeal membranes </li></ul><ul><ul><li>structure </li></ul></ul><ul><ul>...
Introduction <ul><li>my background: phospholipid bilayers </li></ul><ul><ul><li>Archaea: monolayer </li></ul></ul><ul><li>...
Archaeal membranes (1) <ul><li>ester vs ether </li></ul><ul><ul><li>‘ normally’: di-esters of glycerol  and fatty acid cha...
Archaeal membranes (2) <ul><li>tetraether: phytanyl chains in some Archaea are linked </li></ul><ul><ul><li>form a mono la...
Archaeal membranes (3) <ul><li>Archaea lack  murein </li></ul><ul><ul><li>Peptidoglycan, forms rigid cell wall sacculi in ...
Evolutionary consideration (1) <ul><li>precells: phospholipids with racemic glycerophosphate backbone  </li></ul><ul><li>s...
Evolutionary consideration (2) Tree of Life <ul><li>Bacteria: first common feature (murein), then diversified </li></ul><u...
Flagella and membrane proteins (1) <ul><li>Archaeal: spike like structure generating thrust by rotating </li></ul><ul><li>...
Flagella and membrane proteins (2) <ul><li>membrane proteins: 60% of the proteins in prokaryotes </li></ul><ul><ul><li>inf...
Cytoskeleton <ul><li>Actin, central component of eukaryotic cytoskeleton </li></ul><ul><li>Archaeal homolog  Ta0583 from T...
Conclusion <ul><li>unique in cell membrane composition and organization </li></ul><ul><li>Archaea share structural basics ...
Literature <ul><li>- Mario de Rosa, Agata Gambacorta, Allesandra Gliozzi: Structure, Biosynthesis and physicochemical  pro...
Literature <ul><li>- Sonia L. Bardy, Sandy Y. M. Ng and Ken F. Jarrell: Prokaryotic motility structures; Microbiology (200...
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small overview on Archaea

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A small overview on the key differences between the three domains of life, focusing on Archaea.

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  • small overview on Archaea

    1. 1. Structure of Archaea What makes them so unique compared to bacteria and eukaryotes? C.M. van Gorkum; Microbiology of Man, Animals, Food and Environment
    2. 2. Overview <ul><li>Introduction </li></ul><ul><li>Archaeal membranes </li></ul><ul><ul><li>structure </li></ul></ul><ul><ul><li>organisation </li></ul></ul><ul><ul><li>rigidity </li></ul></ul><ul><li>Evolutionary consideration </li></ul><ul><li>Flagella & membrane proteins </li></ul><ul><li>Cytoskeleton </li></ul><ul><li>Conclusion </li></ul>
    3. 3. Introduction <ul><li>my background: phospholipid bilayers </li></ul><ul><ul><li>Archaea: monolayer </li></ul></ul><ul><li>Archaea unique in structure and organization? RNA polymerase, translation system, transfer RNA, 5S ribosomal RNA, cell wall, and lipids </li></ul>Woese, 1994 Bacteria Eukaryotes - small size - histones - structural simplicity - translation system - no nucleus - sequence 5S RNA - no organelles - seq ribosomal proteins - low DNA content
    4. 4. Archaeal membranes (1) <ul><li>ester vs ether </li></ul><ul><ul><li>‘ normally’: di-esters of glycerol and fatty acid chains </li></ul></ul><ul><ul><li>Archaea: ether-linked isoprenoid like chains </li></ul></ul><ul><ul><ul><li>advantages: oxidation; high temperatures; alkaline pH; phospholipases </li></ul></ul></ul><ul><li>fatty acyl versus phytanyl </li></ul><ul><ul><ul><li>less segmentary rotation </li></ul></ul></ul><ul><li>sn1,sn2 versus sn2,sn3 </li></ul><ul><li>Result: </li></ul><ul><li>- more resilient </li></ul>Albers et al., 2000 Structure of cell membranes
    5. 5. Archaeal membranes (2) <ul><li>tetraether: phytanyl chains in some Archaea are linked </li></ul><ul><ul><li>form a mono layer of bipolar lipids </li></ul></ul><ul><ul><ul><li>lowers permeability of membrane decreasing proton leakage at low pH or high temperature: helps maintaining PMF </li></ul></ul></ul><ul><li>prokaryotes: adaptations of the lipid composition </li></ul><ul><li>Archaea: cyclization </li></ul>Albers et al., 2000 Organization of membrane lipids
    6. 6. Archaeal membranes (3) <ul><li>Archaea lack murein </li></ul><ul><ul><li>Peptidoglycan, forms rigid cell wall sacculi in almost all taxa of bacteria </li></ul></ul><ul><li>Archaea employ unrelated alternatives </li></ul><ul><ul><li>no target for classical antibiotics (murein) </li></ul></ul><ul><ul><ul><li>keep in mind for pathogenic archaea </li></ul></ul></ul><ul><li>majority is gram negative: </li></ul><ul><ul><li>only proteinaceous or glycoproteinaceous cell envelopes (S-layers) or </li></ul></ul><ul><ul><li>reminiscent of the glycocalyx (polysaccharide or polypeptide slime) of eukaryotes </li></ul></ul>Archaeal membrane rigidity Kandler & König, 1998
    7. 7. Evolutionary consideration (1) <ul><li>precells: phospholipids with racemic glycerophosphate backbone </li></ul><ul><li>spontaneous physicochemical phase separation </li></ul><ul><ul><li>more homochiral membrane segments </li></ul></ul><ul><ul><li>more-stable lipid membranes. </li></ul></ul><ul><li>these advanced precells (with G-1-P and G-3-P backbones) are supposingly the ancestors of bacteria and Archaea </li></ul>Wächtershäuser’s hypothesis Koga & Morii, 2007
    8. 8. Evolutionary consideration (2) Tree of Life <ul><li>Bacteria: first common feature (murein), then diversified </li></ul><ul><li>Archaea: gained features (G-3-P, cell envelop ) after domain separation </li></ul>murein cell wall cell envelop polymers glycocalyx
    9. 9. Flagella and membrane proteins (1) <ul><li>Archaeal: spike like structure generating thrust by rotating </li></ul><ul><li>Bacterial: whip like structure slapping filament as propeller </li></ul><ul><li>A: built from base </li></ul><ul><li>B: built from tip </li></ul><ul><li>no encoding genes, </li></ul><ul><li>no flagellin similarity </li></ul><ul><li>Archaea: type IV pili </li></ul><ul><li>A: bacterial-like </li></ul><ul><li>chemotaxis system </li></ul>Features in common with bacteria Bardy et al., 2003
    10. 10. Flagella and membrane proteins (2) <ul><li>membrane proteins: 60% of the proteins in prokaryotes </li></ul><ul><ul><li>information, especially of (hyper)thermophilic Archaea, is hard to gather </li></ul></ul><ul><li>ABC (ATPase binding cassettes) primary transporters </li></ul><ul><li>secondary transporters employing electrochemical gradients </li></ul><ul><ul><li>uniport, symport, antiport </li></ul></ul><ul><ul><li>only small number of homologues </li></ul></ul><ul><li>no group translocation systems </li></ul><ul><li>Archaea: mostly binding-protein-dependent ABC type </li></ul><ul><ul><li>can scavenge solutes at very low concentrations (high binding affinities) </li></ul></ul>Features in common with bacteria Albers et al., 2000
    11. 11. Cytoskeleton <ul><li>Actin, central component of eukaryotic cytoskeleton </li></ul><ul><li>Archaeal homolog Ta0583 from Thermoplasma acidophilum </li></ul><ul><li>assembles into bundles of filaments similar to actin </li></ul><ul><ul><li>forms a helix with alike filament width and axial repeating unit length </li></ul></ul><ul><li>greater resemblance with actin than bacterial MreB and ParM </li></ul><ul><ul><li>polymerization characteristics </li></ul></ul><ul><ul><ul><li>requirement for Mg2 + ; critical concentration; repeating unit size </li></ul></ul></ul><ul><ul><li>phylogenetic analysis </li></ul></ul><ul><li>Ta0583 lower specificity for NTPs, so more primitive </li></ul>Feature in common with eukaryotes Hara et al., 2007
    12. 12. Conclusion <ul><li>unique in cell membrane composition and organization </li></ul><ul><li>Archaea share structural basics with their fellow prokaryotes: </li></ul><ul><ul><li>size, organelles, flagellum, membrane proteins </li></ul></ul><ul><li>some basic characteristics are shared with eukaryotes: </li></ul><ul><ul><li>glycocalyx </li></ul></ul><ul><ul><li>Ta0583 has the ancient characteristics of actin </li></ul></ul><ul><li>higher order protein machinery is shared with eukaryotes </li></ul>Unique compared to bacteria and eukaryotes?
    13. 13. Literature <ul><li>- Mario de Rosa, Agata Gambacorta, Allesandra Gliozzi: Structure, Biosynthesis and physicochemical properties of Archaebacterial Lipids; Microbiological Reviews, Mar. 1986, p. 70-80 Vol. 50, No. 1 </li></ul><ul><li>- Carl R. Woese: There Must Be a Prokaryote Somewhere: Microbiology's Search for Itself; Microbiological Reviews, Mar. 1994, p. 1-9 Vol. 58, No. 1 </li></ul><ul><li>- Simonetta Gribaldo and Celine Brochier-Armanet: The origin and evolution of Archaea: a state of the art; Phil. Trans. R. Soc. B (2006) 361, 1007–1022 </li></ul><ul><li>- Sonja-Verena Albers, Jack L.C.M. van de Vossenberg, Arnold J.M. Driessen and Wil N. Konings: Adaptations of the Archaeal cell membrane to heat stress; Frontiers in Bioscience 5, d813-820, September 1, 2000 </li></ul><ul><li>- Yosuke Koga and Hiroyuki Morii: Biosynthesis of Ether-Type Polar Lipids in Archaea and Evolutionary Considerations; Microbio. and Mol. Bio. Reviews, Mar. 2007, p. 97–120 Vol. 71, No. 1 </li></ul><ul><li>- O. Kandlera and H. König: Cell wall polymers in Archaea (Archaebacteria); CMLS, Cell. Mol. Life Sci. 54 (1998) 305–308 </li></ul><ul><li>- Margit Sára and Uwe B. Sleytr: S-Layer Proteins; Journal of Bacteriology, Feb. 2000, p. 859–868 Vol. 182, No. 4 </li></ul>
    14. 14. Literature <ul><li>- Sonia L. Bardy, Sandy Y. M. Ng and Ken F. Jarrell: Prokaryotic motility structures; Microbiology (2003), 149, 295–304 </li></ul><ul><li>- Futoshi Hara, Kan Yamashiro, Naoki Nemoto, Yoshinori Ohta, Shin-ichi Yokobori, Takuo Yasunaga, Shin-ichi Hisanaga, and Akihiko Yamagishi1: An Actin Homolog of the Archaeon Thermoplasma acidophilum That Retains the Ancient Characteristics of Eukaryotic Actin; Journal of Bacteriology, Mar. 2007, p. 2039–2045 Vol. 189, No. 5 </li></ul><ul><li>- Natalya Yutin, Kira S. Makarova, Sergey L. Mekhedov, Yuri I. Wolf, and Eugene V. Koonin: The Deep Archaeal Roots of Eukaryotes; Mol. Biol. Evol. 25(8):1619–1630. 2008 </li></ul><ul><li>- Using the Taxonomy browser at NCBI, the five suggested phyla for Archaea were collected. This browser holds no authority though, so for the background readers should consult the writers mentioned by the Taxonomy browser: </li></ul><ul><li>Crenarchaeota and Euryarchaeota: both Woese et al. 1990 and Garrity & Holt 2002 </li></ul><ul><li>Korarchaeota: Barns et al. 1996 </li></ul><ul><li>Nanoarchaeota: Huber et al. 2002 </li></ul><ul><li>Thaumarchaeota: Brochier-Armanet et al. 2008 </li></ul>

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