e-e-

e-e-

Fisiología microbiana Bota 6006

endoespora

células hijas (1-7)

flagelo

tallo

Thiomargaritanamibiensis

1mmBdellovibrio

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.

• Tres linajes distintivos (2 Prokarióticos/1 Eucariótico) Archaea, Bacteria & Eucaria

• la raíz del árbol de la vida representa una forma ancestral común

• 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

EL ARBOL DE LA VIDA

basado en secuencias de

genes de RNA ribosomal 16S

Caracteristicas Bacteria Archaea Eukarya

Peptidoglycan Yes No NoLipids Ester linked Ether linked Ester linked

Ribosomes 70S 70S 80SInitiator tRNA formyl-Met Met MetIntrons in tRNA No Yes YesRibosomes sensitive to diphteria toxins

No Yes Yes

RNA polymerase 1

(4 subunits)

Several

(8-12 subunits)3

(12-14 subunits)

Histones No Yes Yes

Prokaryotic cell wall

The primary function of the CW is to protect the cell from bursting. There areonly two types of CW in Bacteria:

PeptidoglycanChemical structure

G+ Cell Wall

15-30 nmthick

Covalently linkedTo the peptidoglycan

N-acetil ácido murámico (mureína)

Attachment to peptidoglycan

or glycerol

Teichoic acid attachment

Polyanionic polymers of ribitol-PO4Or glycerol-PO4.

Lipido AEndotoxina, fiebre, necrotización de tejidos fallocardíaco

Polisacárido medularPolisacárido O-específicodesata reacciones alérgicas

LPS

It produce a permeability barrier to hydrophobic compounds:antibiotics, dyes (eosin-methylene blue), bile salts

Porin are major proteins in the outer envelop that form small non-specifichydrophilic channels that allow the diffusion of low molecular weightneutral 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 reactions2) osmotic regulation3) solute transport4) protein secretion5) degradation by phosphatasesand nucleases.6) Detoxification

Cell membrane

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.

>100 differentProteins. Integraland peripheral.

Ácidos grasos

Rol estructural en la membrana citoplasmica

Archaea

Cytoskeleton

FtsZ is a cell division protein related to tubulin.

Phase contrast

Nucleoid stain

FtsZ stain

Nucleoid stainFtsZ stain

Streptococcus hemolyticus

Wall band

Cell Shape

Rod-shape

perítrico monotricolofótrico

amfitrico

Bacterial Flagella

Los flagelos son filamentos helicoidales y rígidos de un diámetro de ~20nmy que rota como una hélice.

Estos consisten de: basal body, a hook, filament, motor, switch, exportapparatus, capping and junction proteins.

Basal BodyMS ring

FliF protein

FlgH protein

FlgI protein

Central rodFlgB,C,F

Flagella and its components

C ring

The motor

Startor (MotA, B proteins)

Rotor (FliG proteins)

C ring (FliM, N)

H+ pass across the CM thru the MotA,Bwhich provide the torque to rotate the rotor.

The motor: how does it change direction?

Startor (MotA, B proteins)

Rotor (FliG proteins)

C ring (FliM, N)

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.

Chemiotactic effect on motility

The motorFliC 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 hookTo 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