Transcript Bacteria - Eubacteria

How do Archaea tolerate the heat?
• Proteins stabilized by more ionic bridges between amino
acid r-groups and more-hydrophobic core amino acids
• Heat shock protein (chaperonins) refold denatured
proteins…Pyrococcus 121°C for 1 hour!
• DNA depurination reduced by presence of 2,3diphosphoglycerate.
• DNA supercoiling by reverse gyrase reduces denaturation
• Sac7d in Sulfobolus is a minor groove protein increases the
melting temperature by 40°C
• Histone-like proteins help stabilize DNA as well
• Heat-resistant di-bi-phytanyl diether lipid membranes
(monolayer) prevent delamination of membrane
Cell Membrane Structure
Composed of diglycerides
R group may be phosphate, sulfate, or sugar
Long chain branched hydrocarbon (not fatty acid)
Hydrocarbons may be C20 or C40
If C20, the membrane is a bilayer:
O
O
O
O
R
R
If C40, the membrane is a monolayer
O
O
O
O
R
R
In some species, the membrane is a mixture of both C20 and C40
diglycerides forming a mixed mono-/bi-layer
Cell Structure: Movement
hook
basal rings
and rod
directional rotation?
anchorage
rotation
stiff helical flagellum
flagellin protein
is rotated by “motor apparatus”
in the membrane by H+ ATPase
at rates of 200-1700 rps
(>12,000 rpm!)
Motile Archaea often have
multiple flagella in a tuft at one
place on the cell surface
thermotaxis:
movement to heat
Taxis:
movement toward stimulus
phototaxis:
movement toward light
chemotaxis:
movement to chemicals
Cell Structure: Nucleoid
Nucleoid - genome
one circular DNA molecule + plasmids
histone-like protein association (~eukaryotic)
genome smaller than typical bacteria
sequences closer to eukaryotic homologs
introns in rRNA and tRNA genes
operon regulation in some genes like bacteria
attached to cell membrane
transcription by RNA polymerase (~POLII@TATA)
replication by DNA polymerase
separation of chromosomes
cytokinesis by furrowing
70S Ribosome
rRNA + protein + ribozymes
translation of mRNA into protein
Process called binary fission
NOT mitosis!
•Genome and copy are identical
•Genome is haploid
•There is no synapsis
•There is no recombination
Cell Structure: Genetic Structure
Nucleoid - main chromosome is circular but
associated with histone-like proteins
Replicons - small circular DNAs
with additional essential genes
• Genes are generally in clusters
in operon-like situations
• Chromosomes have insertion
sites for transposition events
• rRNA and other genes have
intron sequences
• How the movements of the
multiple units is coordinated is
not yet fully known
Halobacterium salinarium
http://biology.kenyon.edu/Microbial_Biorealm/
archaea/halobacterium/halobacteria_1.jpg
Aerobic Respiration
Up to 5 M (25% NaCl)!
Great Salt Lake, Utah
Red Sea, Asia Minor
3 chromosomes
Main chromosome 2,015 kb
191 kb replicon
366 kb replicon
Replicons have genes for:
DNA polymerase
Transcription factors
Mineral uptake (K, PO4)
Cell division
The genome has many insertion sites
for foreign genes
Bacteriorhodopsin:
Protein + retinal
Amax 280 UV, 570 green nm
energy for proton transport and
phosphorylation without
photosynthesis!
Periplasmic
space
Retinal
Cell
Membrane
lsu.epfl.ch/sh/bR_full.pdf
Cytoplasm
www.hawaii.edu/microbiology/ Alam/publications/PNAS96-ZHANG.pd
Bacteriorhodopsin
absorbs green from the
visible spectrum, so
what color is the
pigment?
Hint: it reflects the
other colors of the
spectrum
Which of these metabolic pathways
is Halobacterium demonstrating?
• Photoautotrophism
√
• Photoheterotrophism
• Chemoautotrophism
• Chemoheterotrophism
Hint:
• Light for energy
• Chemicals for carbon
Methanococcus jannischii
Isolated from “white smoker”
hydrothermal vent
2600m deep on the East Pacific Rise
http://www.bact.wisc.edu/Bact303/Methanococcus.jpeg
What does this electron
micrograph tell you?
…about cell shape?
…about motility?
Methanogen
Obligate anaerobe
H2 as energy source
CO2 as carbon source
CH4 as byproduct of metabolism
Temperature: 50-86°C
Other species found in
cow rumen (first stomach)
Cow belches 50 L of methane per day
Which of these metabolic pathways
is Methanococcus demonstrating?
• Photoautotrophism
• Photoheterotrophism
√
• Chemoautotrophism
• Chemoheterotrophism
Hint:
• H2 for energy
• CO2 for carbon
Thermus aquaticus
QuickTi me™ and a
T IFF (Uncompressed) decompressor
are needed to see thi s pi cture.
http://www.molgen.mpg.de/~ag_ribo/
ag_franceschi/franceschi-projects-30S.html
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
Gram negative
Thermophile isolated from
Yellowstone Hot Spring
Optimum temperature 85°C
Stability of macromolecules excellent
Enzymes for research or commercial use
Taq polymerase is the enzyme of PCR
(Polymerase Chain Reaction)
Lives near cyanobacteria which feed
Thermus
http://sci.agr.ca/crda/images/BACTERI1.JPG
Which of these metabolic pathways
is Thermus demonstrating?
• Photoautotrophism
• Photoheterotrophism
• Chemoautotrophism
√
• Chemoheterotrophism
Hint:
• Organic chemicals for energy
• Organic chemicals for carbon
Sulfolobus acidocaldarius
75°C Optimum
Strict aerobe
pH 1 to 6
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
http://dac.molbio.ku.dk/Sulfolobus.jpg
Oxidize Sulfur or can use
Fe2+ or MnO42- as electron
acceptors…uses
glycolysis and TCA cycle
Pilus and conjugation
plasmids not similar to
bacterial ones
Which of these metabolic pathways
is Sulfolobus demonstrating?
• Photoautotrophism
• Photoheterotrophism
• Chemoautotrophism
√
• Chemoheterotrophism
Hint:
• Organic chemicals for energy
• Organic chemicals for carbon