Unit 5 Flashcards
5 phyla of Archaea
Euryarchaeota
Thaumarchaeota
Nanoarchaeota
Korarchaeota
Crenarchaeota
what is the phylogenetic tree based on?
16S r RNA
what is the evolution of Archaea driven by?
HGT between phyla
what are the common traits shared by all Archaea?
- ether linked lipids
- lack of peptidoglycan in cell walls
- structurally complex RNA polymerases
- RNA polymerase resemble eukaryotic enzymes
- extreme metabolic diversity
- chemoorganotrophic or chemolithotrophic organisms
- aerobic and anaerobic organisms
Euryarchaeota
halophilic (salt-loving obligate aerobes)
methanogens (strictest anaerobes)
hyperthermophilic
acidophilic
extremophilic and non-extremophilic
what are the 2 organisms representing halophilic archaea and their characteristics?
halococcus
haloquadratum
- usually aerobic
- anaerobic is possible
- no fermentation
halococcus
largest plasmids in nature
plasmid is 30% of total cellular DNA
haloquadratum
gas vesicles for floating in hypersaline enviro
what do organisms do in high solute enviro?
either accumulate or synthetize solutes intracellularly (compatible solutes)
function of compatible solutes?
prevent dehydration under conditions of high osmotic strength
what do certain Euryarchaeota do if they do not synthesize or accumulate organic compounds?
pump large amounts of K+ from enviro into cytoplasm
- different in K+ levels maintains pos water balance
hyperthermophilic organisms
thermococcus
thermoplasma
thermoplasma
- cell wall lacking
- small genome
- DNA in globular eukaryotic-like structures
- 55C
- pH 2
- sulfate respiration
- No sterols
- Lipoglyan cell wall
methanogens
produce methane as integral part of energy metabolism
- major source of biogenic methane in nature
Methanocaldococcus jannaschii
model methanogen
enzymes for methanogenesis
central metabolic enzymes and cell division machinery- resembles bacterial structures
transcription and translation genes resembles eurkayotic organisms
acidophilic organisms
ferroplasma
picrophilus
Ferroplasma
cell-wall lacking
strong acidophile
non thermophile
Fe2+ as e donor
Picrophilus
phylogenetic relative Ferroplasma
more acidophilic than Ferrroplasma
Methanopyrus
hyperthermophilic methanogen
unique lipids- bacterial and archaeal features
archaeal- glycerol side chain with saturated phytanyl
bacterial- glycerol side chain with fatty acids
- unusual lipids may help stabilize the cytoplasmic membrane at its high growth temps
Thermococcus
organic substrates
sulfur respiration
Nitrosopumilus maritimus
- Thaumarchaeota
AOA
CO2 fixation - grows at NH3 concentrations that are 100x lower than those required by bacterial nitrifiers
- all isolated species are chemolithotrophic ammonia-oxidizers
- can grow at v low concentrations of NH3
- unique lipid called crenarchaeol
- major role in controlling NH3 levels in oceans
Nanoarchaeum equitans
- Nanoarchaetoa
- one of the smallest
- no growth in pure culture
- growth only when attached to surface of host
- host - Ignicoccus hospitalis (hyperthermophilic species of Crenarchaeota- hospitable fireball)
- grows at high temps
- metabolically dependent on host
ignicoccus
performs H2 oxidation and S^0 reduction along with CO2 fixation
what genes did Nanoarchaeum equitans lose?
- amino acids biosynthesis
- nucleotides production
- coenzymes
- ATPase genes
what genes remained in Nanoarchaeum equitans?
- lipids biosynthesis
- glycolysis
- molecular machinery
- DNA repair enzymes
Korarchaeum cryptofilum
- Korarchaeota
- cryptic filament of youth
- obligately anaerobic chemoorganotroph
- hyperthermophile
- inability of K. cryptofilum to synthesize molecules essential for its own growth may be explained by evolution of mutual dependence as described by Black Queen hypothesis
- incapable to synthetize necessary molecules for their growth
- evolution of mutual dependence
Black Queen hypothesis
evolutionary strategy to lose costly functions in favor of improving growth efficiency
- results in mutants becoming obligately dependent upon provider to produce necessary resource
Crenarchaeota
- hyperthermophiles
- species that grow optimally above boiling point of water
- chemolithotrophic autotrophs
- primary producers in extremes
Eocyte tree
- 2D
- 2 domains
- ancestor of eukaryotes was thermophilic organism that did not have nucleus
- organisms called eocytes
- 1 branch with nucleus separated (Karyocytes)
- branch 2 was prokaryotic (B and A)
- unrooted
3D tree
- prokaryotes branched to B and A
- eukaryotes developed as separate lineage
- all biochemical data, DNA and RNA polymerases that were added late onto the tree were in favor of model
- unrooted
what do Eukarya and Archaea have in common?
ancestral branch
was the branch the same for eukarya, archaea and bacteria?
no
are archaea distantly related to bacteria?
yes
what are archaea and bacteria?
not monophyletic groups
what was the last group that bridged A and E?
Asgard
what group has sequence homology to core domains in eukaryotic endosomal sorting complexes proteins?
Cell division machinery in Crenarchaeota
what was discovered in Asgard arachae?
homolog of eukaryotic ESP
ESCRT
- simple, ancient origins
- many archaeal have homologues of ESCRT-III and Vps4
roles of ESCRT-III and Vps4
role in cytokinesis, extracellular vesicle formation and viral exit
what is an example of homologue systems in Ascard archaea?
ESCRT machinery
