Download 8. Prokaryotic diversity II

2/10/11
Prokaryotic Diversity II Coming attractions
Class announcements
1.  Today – no clickers; Friday – probably clickers
2.  Discuss phylogenetic tree homework in your study
group, but write up the HW on your own
3.  Friday – phylogenetic tree HW due
4.  Friday – review exercises from the diagnostic exam
due
5.  Early next week – review sessions for first mid-term
exam
6.  Use your study group to prepare for first mid-term
exam
7.  Next Wednesday – first mid-term exam
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Evolutionary origins
Basic features
Bacteria – several major groups
Bacteria - pathogenesis
Archaea – extremophiles
Metabolic diversity
Bioenergetics – redox reactions
Bioenergetics - electron transport
chains
•  Biogeochemical cycles
Copyright © 2002 Pearson Education, Inc.
Prokaryotic cell structure
Prokaryotic cell structure
C & R Fig 7.4
Escherichia coli
Methanobacterium foricum
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Major characteristics of 3 domains of life
Bacteria
Archaea
Eukarya
Nucleus
No
No
Yes
Chromosome (C)
One circular C with 1
origin of DNA replication
One circular C with 1-3
origins
Several to many linear C
with multiple origins
Organelles
No
No
Yes
Growth forms
Most unicellular, some
multicellular
All unicellular
Many unicellular, many
multicellular
Reproduction
Binary fission
Binary fission
Often sexual
Lipid structure
Glycerol bonded to
unbranched fatty acids
via ester links
Glycerol bonded to
branched lipids via ether
links
Glycerol bonded to
unbranched fatty acids via
ester links
Cell wall polymers
Peptidoglycan
Wide variation, no
peptidoglycan
If present, chitin or cellulose
Histone proteins
No
Yes
Yes
Transcription &
translation
One simple RNA
polymerase, start aa formylmet, 70S ribo
Several complex RNA
polymerases, start aa met, 70S ribosomes
Several complex RNA
polymerases, start aa - met,
80S ribosomes
Essential features
Bacteria
Archaea
Eukarya
Evolution of complex
cell structure
last common ancestor/ancestral community Evolution of simple
cell structure
Evolution of complex
information processing
Evolution of simple
information processing
Evolution of simplest life
See F Table 28.1
Jeff sez, “For best results, why don’t you think about
using Charlie Darwin’s model of a branching tree?”
The power of tree thinking: organizes important information in evolutionary model
reconstructs the traits characterizing each group
summarizes an evolutionary story
provides explicit testable hypotheses
Coming attractions
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Evolutionary origins
Basic features
Bacteria – several major groups
Bacteria - pathogenesis
Archaea – extremophiles
Metabolic diversity
Bioenergetics – redox reactions
Bioenergetics - electron transport
chains
•  Biogeochemical cycles
eukaryote-specific
characteristics
(derived similarity)
common A/E
ancestor
characteristics
LUCA/LUCAC
characteristics
(primitive
similarity)
predicted
characteristics
of protolife
Copyright © 2002 Pearson Education, Inc.
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Bacteria - diversity
Unicellular
shapes
Leeuwenhoek’s
microscope
Nester et al. Fig 10.1
>40 major lineages roughly corresponding to kingdoms
>98% of known prokaryotic species
104 described species, but 107 estimated species (or many more!)
Almost overwhelming diversity of metabolisms, habitats, growth forms, and lifestyles within
the basic prokaryotic framework
•  Poor coupling between phylogeny and physiology (some notable exceptions) – WHY?
•  Great ecological significance - biogeochemical cycles, symbiotic relationships
•  Great human significance - biotechnology, medicines, foods, bioremediation, and some
major diseases
Leeuwenhoek
(1684) “wee
animalcules”
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Structural diversity - other examples
Spheres
(cocci)
Rods
(bacilli)
Helices
(spirilla)
MMP Fig. 1.9
Copyright © 2002 Pearson Education,
Inc.,
Bacterial cell walls (F. Fig. 28.14)
Grampositive
cells
Gramnegative
cells
www.microscopy-uk.org.uk/mag/imagsmall/merismopedia.jpg
Merismopedia (cyanobacterium)
Caulobacter
(stalked
proteobacterium)
Freeman Fig. 27.21
Chondromyces
(myxobacterium with
fruiting bodies)
•  The Gram stain separates all bacteria into two
classes based on major differences in their cell walls.
•  Gram-positive bacteria (colored purple) have
simpler cell wall with much peptidoglycan.
microvet.arizona.edu/Courses/MIC205/Exams/pleomorphic2.gif
Freeman Fig. 27-19
Nostoc (cyanobacterium)
Unindentified pleomorphic bacterium
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Gram-positive bacteria
Bacterial cell walls (F. Fig. 28.14)
Grampositive
cells
Gramnegative
cells
•  Gram-negative bacteria (colored pink)
have more complex cell walls producing
an outer membrane on the cell wall
composed of lipooligosaccharides (LOS).
•  Outer membrane has toxic LOS, inhibits
antibiotic entry and resists host defenses.
Dan Stein (CBMG)
•  Gram-positive cell walls - one cell membrane, thick peptidoglycan cell wall
•  Two subgroups - low GC (20-40%) or high GC (60-80%) ratio in DNA base
composition
•  Anaerobic, facultative aerobic, and aerobic species
•  Principal metabolic strategy - chemoheterotrophs (energy and carbon from a
wide range of organic compounds) - certain species utilize and/or produce
specific organic acids (e.g. formic, acetic, lactic, butyric, and propionic acids)
•  Foods - yogurt, pickles, sauerkraut, and swiss cheese
•  Antibiotics - penicillin, streptomysin, erythromycin (Streptomycetes spp.);
bacitracin, gramicidin, and polymyxin (Bacillus spp.); insect-specific toxins
(B. thuringiensis - Bt toxin)
•  Diseases - anthrax (B. anthracis), tuberculosis (Mycobacterium tuberculosis)
MMP Fig. 12.55
Lactobacillus delbreuckii
Proteobacteria
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Largest group of known bacteria
Gram-negative cell walls – two membranes with thin peptidoglycan cell wall
Five subgroups - alpha, beta, gamma, delta, and epsilon subgroups
Anaerobic, facultative aerobic, and aerobic species
Greatest diversity of metabolic strategies - photoautotrophs (non-oxygenic
photosynthesis - light as energy source), chemoautotrophs (inorganic compounds as
energy sources), and chemoheterotrophs (organic compounds as energy sources)
Major biological contributors to biogeochemical cycling of important elements,
including C, N, P, and S.
Escherichia coli - the most studied organism (other than a particular primate species)
Intestinal bacteria, such as E. coli, synthesize essential B and K vitamins.
Vibrio group - bioluminescent bacteria in the light organs of deep-sea fish
Diseases - bubonic plague (Yersinia pestis), cholera (Vibrio cholerae), bacterial
meningitis (Neisseria meningitidus), typhoid fever (Salmonella typhi)
MMP Fig. 12.4
Nester et al. Fig. 3.43
E. coli
MMP Fig. 12. 73
Streptomycetes spp.
α-proteobacteria
•  Symbiotic associations with eukaryotic hosts - “the camp
followers of eukaryotes”
•  Rhizobium - nitrogen fixation in legume hosts
•  Agrobacterium - crown gall disease, plant genetic engineering
•  Ricksettia - tiny intracellular parasites in animals
•  An ancient aerobic alpha - original source of eukaryotic
mitochondrion – more after 1st mid-term exam
Nester et al. Fig. 11.27
Nester et al. Fig 11.22
Purple sulfur bacteria
Nester et al. Fig 11.17
Bacillus anthracis
Flashlight fish
Legume root nodules
Nester et al. Fig 11.21
Crown gall disease
MMP Fig. 12.29
Ricksettsia in insect cell
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Cyanobacteria - “biology’s working class heroes”
•  Photoautotroph (oxygenic photosynthesis) with chlorophyll a
•  Use H2O as the ultimate electron donor for photosynthetic
electron transport, with O2 as the “waste product”
•  Wide variety of growth forms - solitary unicells, colonies,
filaments, and branching filaments
•  Also gram-negative walls, but no pathogens
•  Profound historical impact on Earth’s atmosphere
and the distribution of all organisms
Beth Gantt
•  Evolutionary source of algal and plant chloroplasts
(CBMG)
MMP Fig. 12.78
Gleothece sp.
Oscillatoria sp.
Cellular differentiation in few cyanobacteria
•  Small green vegetative cells photosynthesis
•  Brown heterocysts - nitrogen
fixation
•  Large green endospores –
dormancy
•  Contrast to eukaryotes?
MMP Fig. 12.80
Anabaena sp.
MMP Fig. 12.79
Fischerella sp.
Geological history of prokaryotic gas exchange
Intercellular transport
Evolutionary consequences of O2 production
C & R Fig. 26.5
Banded iron formations
Kasting Sci. Am. 2004
What were the evolutionary consequences of O2 production?
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Coming attractions
Evolutionary consequences of O2 production
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Evolutionary origins
Basic features
Bacteria – several major groups
Bacteria - pathogenesis
Archaea – extremophiles
Metabolic diversity
Bioenergetics – redox reactions
Bioenergetics - electron transport
chains
•  Biogeochemical cycles
C & R Fig. 26.5
Banded iron formations
•  Eventually, atmosphere changed from reducing to oxidizing
conditions.
•  All the soluble Fe2+ in the oceans was oxidized to form insoluble
Fe3+ that precipitated to form banded iron formations
•  All anaerobic organisms became restricted to anoxic environments.
•  The formation of ozone (O3) layer restricted mutagenic UV
radiation.
•  Allowed for the origin of aerobic prokaryotes and larger eukaryotes
Copyright © 2002 Pearson Education, Inc.
Pathogens - disease-causing organisms
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Antibiotics - bacteria-specific compounds
Prokaryotes – only bacteria are pathogenic
Dis-ease - host symptoms resulting from microbial colonization
Host-pathogen interactions - BSCI 223
Evolutionary perspectives – LGT consequences
–  the acquisition of antibiotic resistance from other bacteria
–  the acquisition of pathogenic ability by non-pathogens
http://history.smsu.edu/jchuchiak
Bubonic plague (black death)
http://pearl.agcomm.okstate.edu
Soybean blight
Different antibiotics target different structures or processes.
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Transmission of antibiotic
resistance via vertical
gene transfer
Transmission of
antibiotic resistance
VGT to its progeny
(same species)
antibiotic drug selects for
resistant bacterium
then its resistant progeny
multiply in the presence of the
antibiotic
Nester et al. Fig. 21.13
R. Stewart
Pathogens - disease-causing organisms
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Lateral gene transfer to
other species,
perhaps pathogens!
R. Stewart from
Nester et al. Fig. 21.13
Pathogenicity islands (PI’s)
Prokaryotes – only bacteria are pathogenic
Dis-ease - host symptoms resulting from microbial colonization
Host-pathogen interactions - BSCI 223
Evolutionary perspectives – HGT consequences
–  the acquisition of antibiotic resistance from other bacteria
–  the acquisition of pathogenic ability by non-pathogens
PI - gene clusters that
elicit disease responses
One PI in many pathogens
encodes Type III secretion
system (SS)
Type III SS - injects toxic
proteins into host cells
http://history.smsu.edu/jchuchiak
Bubonic plague (black death)
http://pearl.agcomm.okstate.edu
Soybean blight
Nester et al. Fig 19.4
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Molecular genetics of
Type III secretion
Mammalian pathogens"
Yersinia spp – bubonic plague"
Salmonella spp. – typhoid fever"
Shigella spp. - dysentery"
P. aeruginosa - UTIʼs"
B. pertussis – whooping cough"
Chlamydia spp.- STDʼs"
Plant pathogens"
Pseudomonas syringae!
Erwinia spp"
P. fluorescens
R. solanacearum!
X. campestris!
Burkholderia cepacia!
K"
L"
J"
Steve Hutcheson
(CBMG)
U"
Flagellar biosynthesis"
C"
A"
S" R"
Filamentous phase assembly"
Hrp (hypersensitive response) Central Conserved Region (CCR)"
Summary Questions = Learning Objectives
1.  Be able to group related traits together, such as all
prokaryotic cell features, and then place those grouped
traits on the phylogenetic tree of the three domains.
2.  Use this tree to identify the major traits of bacteria,
archaea, and eukaryotes.
3.  Finally, summarize the current hypothesis about the main
events in the evolution of the three domains.
4.  Be able to relate the features of bacterial cell walls to the
evolution of antibiotics and pathogenic abilities in different
bacterial groups
5.  Identify the key metabolic innovation of cyanobacteria,
and discuss its significance for the evolution of life.
6.  Evaluate the significance of lateral gene transfer for the
dispersal of antibiotic resistance and for the acquisition of
pathogenic ability. Be able to distinguish between these
two phenomena.
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