Tema 1: Estructura y funciónCapitulo 1

e-e-

e-e-

Fisiología microbiana BIOL 4368

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

basadoen secuencias de

genes de RNAribosomal 16S

YesYesNoHistones

3(12-14 subunits)

Several

(8-12 subunits)

1

(4 subunits)

RNA polymerase

YesYesNoRibosomes sensitive to diphteria toxins

YesYesNoIntrons in tRNAMetMetformyl-MetInitiator tRNA80S70S70SRibosomes

Ester linkedEther linkedEster linkedLipids

NoNoYesPeptidoglycanEukaryaArchaeaBacteriaCaracteristicas

micro.magnet.fsu.edu/cells/bacteriacell.html

1) Flagella2) Fimbriae, pili, filaments, and fibrils3) Cell walls4) Periplasm5) Cell membrane6) Cytoplasm7) Cytoskeleton

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 directionof 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 flagellinmonomers 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

Fimbriae, pili, filaments, and fibrils

Pili : estructura filamentosa compuesta de proteínas, envuelta en el proceso de colonización, adhesión o conjugación.

Fimbrias : estructura filamentosa compuesta de proteínas, su función esde adherencia (tejidos animales), colonización de superficies sólidas, motilidad en algunas casos.

Prokaryotic cell wall

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

This is a contribution of the Danish physician, Christian Gram in 1884

- polímero de dos azúcares modificadas (N-acetil glucosaminay N-acetil ácido murámico ) y tetrapéptidos

G = N-acetil glucosaminaM = N-acetil ácido murámico (mureína)

tetrapéptido (4 amino ácidos)

Prokaryotic cell wall

Peptidoglycan

G M G M G M G M

G M G M G M G MM

3 4

enlace β, 1-4

PeptidoglycanChemical structure

M

M

M

M

L-AlaninaD-Acido glutámico

Meso-DAP (ácido diaminopimélico)D-Alanina

L-AlaninaD-Acido glutámicoMeso-DAPD-Alanina

Gram -

M

M

= GlycineL-AlaninaD-GlutaminaL-R3

D-Alanina

L-AlaninaD-GlutaminaL-R3D-Alanina

Gram + interbridge

L-R3 is varible, but usually is Meso-DAP

L-R3 is very varible in G+ cells

S. aureus

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.

G – Cell Wall

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

Estructuras de inclusión

Polímeros de almacenamiento de carbono:poly β-hydroxybutyrate-lípido polimerizado que se almacena

cuando hay fuentes de carbono en exceso. Además se puede Almacenar: phosphato, azufre elemental, magnetite Fe3O4.

Magnetospirillum magnetotacticum, Isochromatium buderi, Rhodovibrio sodomensis

vesículas de gas: compartimiento delimitado por una membrana impermeable al agua y solutos. Solo gases pueden pasar.Presentes en bacterias planctónicas (de existencia flotante)facilita movimiento en respuesta a estímulos ambientales.

Ancyclobacter aquaticus

Cytoskeleton

Microtubules

Microfilaments

Cell shape, movement of cilia and flagella, muscle contraction, endocytosis.

Cytoskeleton

FtsZ is a cell division protein related to tubulin.

Phase contrast

Nucleoid stain

FtsZ stain

Nucleoid stainFtsZ stain

Streptococcus hemolyticus

Wall band

Cell ShapeMreB- This protein is a member of the actin superfamily and is found in manybacteria

Rod-shape Spherical-shape

Crescentin- This protein is found in Caulobacter crescentus and is responsiblefor the vibrioid-shape of the bacterium