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Fisiología microbiana Bota 6006
eee-
e-
endoespora
flagelo
Thiomargarita
namibiensis
tallo
células hijas (1-7)
Bdellovibrio
1mm
1
~1500
nucleotides
Secondary structure of 16S rRNA
Evolutionary distance - # de nucleótidos diferentes y se usan para calcular distancia.
Maximum parsimony - # de nucleótidos diferentes, sus posiciones y la naturaleza
de las diferencias.
EL ARBOL DE
LA VIDA
basado
en secuencias de
genes de RNA
ribosomal 16S
• la raíz del árbol de la vida representa una forma ancestral común
• Tres linajes distintivos (2 Prokarióticos/1 Eucariótico) Archaea, Bacteria & Eucaria
• Archaea & Eucaria son evolutivamente más relacionados
•Archaea están evolutivamente más cercanas a la forma ancestral (más primitivos).
• Eucariotas están más distanciados de la forma ancestral (más evolucionados)
• origen termofílico de los seres vivos
Caracteristicas
Peptidoglycan
Lipids
Ribosomes
Initiator tRNA
Introns in tRNA
Ribosomes sensitive
to diphteria toxins
RNA polymerase
Histones
Bacteria
Archaea
Eukarya
Yes
No
No
Ester linked
Ether linked
Ester linked
70S
No
No
70S
Met
Yes
Yes
80S
Met
Yes
Yes
1
(4 subunits)
Several
(8-12 subunits)
3
(12-14 subunits)
No
Yes
Yes
formyl-Met
Prokaryotic cell wall
The primary function of the CW is to protect the cell from bursting. There are
only two types of CW in Bacteria:
Peptidoglycan
Chemical structure
G+ Cell Wall
Covalently linked
To the peptidoglycan
15-30 nm
thick
Teichoic acid attachment
Polyanionic polymers of ribitol-PO4
Or glycerol-PO4.
Attachment to peptidoglycan
N-acetil ácido murámico (mureína)
or glycerol
LPS
It produce a permeability barrier to hydrophobic compounds:
antibiotics, dyes (eosin-methylene blue), bile salts
Polisacárido O-específico
desata reacciones alérgicas
Polisacárido medular
Lipido A
Endotoxina,
fiebre, necrotización
de tejidos fallo
cardíaco
Porin are major proteins in the outer envelop that form small non-specific
hydrophilic channels that allow the diffusion of low molecular weight
neutral or charged solutes. Examples are LamB, OmpF, OmpC, Tsx.
Periplasm
It is a aqueous compartment containing protein, salts,
oligosaccharide, and peptidoglycan.
What happens in this space?
Specialized activities such as
1) oxidation-reduction reactions
2) osmotic regulation
3) solute transport
4) protein secretion
5) degradation by phosphatases
and nucleases.
6) Detoxification
Cell membrane
>100 different
Proteins. Integral
and peripheral.
Responsible for solute transport, electron transport, photosynthetic electron transport,
the establishment of electrochemical gradients, ATP synthesis, biosynthesis of lipids,
biosynthesis of cell wall polymers, secretions of proteins, the secretion and
uptake of intercellular signals, and responses to environmental signals.
Ácidos grasos
Rol estructural en la membrana citoplasmica
Archaea
Cytoskeleton
Phase contrast
Nucleoid stain
FtsZ stain
Nucleoid stain
FtsZ stain
FtsZ is a cell division protein related to tubulin.
Streptococcus hemolyticus
Wall band
Cell Shape
Rod-shape
Bacterial Flagella
amfitrico
perítrico
lofótrico
monotrico
Los flagelos son filamentos helicoidales y rígidos de un diámetro de ~20nm
y que rota como una hélice.
Estos consisten de: basal body, a hook, filament, motor, switch, export
apparatus, capping and junction proteins.
Flagella and its components
Central rod
FlgB,C,F
FlgH protein
FlgI protein
MS ring
FliF protein
C ring
Basal Body
The motor
H+ pass across the CM thru the MotA,B
which provide the torque to rotate the rotor.
C ring (FliM, N)
Rotor (FliG proteins)
Startor (MotA, B proteins)
The motor: how does it change direction?
The direction of the rotation results in the direction
of the cell (North, south…) and this is related to
CheY-P which are chemotactic proteins and binds FliM.
C ring (FliM, N)
Rotor (FliG proteins)
Startor (MotA, B proteins)
Chemiotactic effect on motility
The motor
FliC is not identical in all bacteria.
20 to 65 kD more importantly only the
C and N-terminal seem to be conserved
(~60%). The filament grows from the hook
To the capping protein by adding flagellin
monomers as it needs.
Furthermore, a cell could have more than
one type of flagellin. E. coli (1),
Caulobacter sp. (3).
Summary of steps in Flagella biosynthesis
Gram-negative Bacteria