Fisiologa microbiana Bota 6006 flagelo tallo 1 1500

Fisiología microbiana Bota 6006 flagelo tallo

1 ~1500 nucleotides Secondary structure of 16 S r. RNA

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 16 S • 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 t. RNA Introns in t. RNA Ribosomes sensitive to diphteria toxins RNA polymerase Histones Bacteria Archaea Eukarya Yes No No Ester linked Ether linked Ester linked 70 S No No 70 S Met Yes 80 S Met Yes 1 (4 subunits) Several (8 -12 subunits) 3 (12 -14 subunits) No 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-PO 4 Or glycerol-PO 4. 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 Lam. B, Omp. F, Omp. C, 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 Fts. Z is a cell division protein related to tubulin.

Streptococcus hemolyticus Wall band

Cell Shape Rod-shape

Bacterial Flagella perítrico amfitrico lofótrico monotrico Los flagelos son filamentos helicoidales y rígidos de un diámetro de ~20 nm 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 Flg. B, C, F Flg. H protein Flg. I protein MS ring Fli. F protein C ring Basal Body

The motor H+ pass across the CM thru the Mot. A, B which provide the torque to rotate the rotor. C ring (Fli. M, N) Rotor (Fli. G proteins) Startor (Mot. A, 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 Che. Y-P which are chemotactic proteins and binds Fli. M. C ring (Fli. M, N) Rotor (Fli. G proteins) Startor (Mot. A, B proteins)

Chemiotactic effect on motility

The motor Fli. C is not identical in all bacteria. 20 to 65 k. D 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