Microbial Physiology Final

Oxidative Phosphorylation

used in respiration (oxygen present), makes ATP, need PMF

3H+ per ATP

Substrate-Level Phosphorylation

Universal, anaerobic, produce ATP (PEP —> Pyruvate)

Photophosphorylation

phototrophs, rxn centers, uses PMF

chemotrophs

use chemical energy

phototrophs

use light energy

autotrophs

CO2 —> reduced Carbon

heterotrophs

reduced carbon —> CO2

ChemoLITHOtrophs

inorganic electron donors

ChemHETEROtrophs

organic electron donor

Allosteric Regulation

small protein impacts enzyme activity

post-translational

sRNA

determine if ribosomal binding site is open or not

post-transcriptional

feedback inhibition

end product stops earlier activity/ translation

post-translational

Covalent Modification

methylation or phosphorylation to change activity

post-translational

RNA Polymerase

aka sigma factors

in bacteria, catalyzes transcription

Activator

Transcription factors, bind upstream of promoter to increase transcription

Repressor

transcription factor, binds downstream promoter/ operator to decrease transcription by blocking RNAP

Gm+ bacteria

thick PG cell wall, no outer membrane

Gm- bacteria

thin cell wall, two membranes- outermembranes contains LPS, porins, and lipoproteins

Archaea

Pseudo-PG/ S-layer cell wall, no outer membrane

Sec-dependent transport system

dominant system, can transport proteins: to the periplasm, into the inner membrane, or the outer membrane

SRP-Dependent Transport

Co-Translational

TAT-System

twin arganine signals, move folded proteins, sec-independent

Transmembrane Spanning Domain

Stop Transfer Sequence

Non-Cleavable Signal Sequence

Type II Transport

major secretion route, SEC-dependent

Type V Transport

“autotransportation”, SEC-Dependent

Type IV Transport

transport protein, virulence and exoenzymes, SEC-Dependent

Type I transport

3 linked proteins, move protein outside cell, ATP hydrolysis, SEC-Independent

Type III Transport

many accessory proteins, transport directly to host, SEC-Independent

Type IV Transport (SEC-Independent)

DNA Transport/ Conjugation

Type VI Transportation

phage-like, inject toxins into host, sheath contracts to push needle w/ virulence factors

Type IV pili

built from subunits of pilin at base, use ATP

Gliding Motility

slime extrusion, A-type motility (myxobacteria)

Twitching Motility

polyermize/ extend pillus, attach to surface of cell, retract and depolymerize

Flagella: Early Gene Expression

σ70 helps express FlnDC —> master regulator

Flagella: Middle Genes

Master regulator + σ70 —> components of basal body, FlgM (anti-σ factor) unbound from σ28 when hook is finished

Flagella: Late Genes

master regulator + σ28 work together to express flagellin, motor, and chemotaxis genes

Repellent Present

MCPs —> CheW —> CheA —> CheB demethylates MCPs and CheY-P causes CW tumble

Attractant Present

MCPs —> CheW —> CheA kinase —> CheY causes CCW movement, CheB unphosphorylated, CheR resets system

Smooth Run Mutant

CCW movement of C-ring, no CheY or Che A

Tumble Mutant

CW movement of C-ring, no CheB or CheZ

Luciferase

mixed function oxidase, needs ATP, participates in redox reactions and reduces coenzymes

Gm- Autoinducer

Acyl Homoserine Lactone (AHL)

Gm- Autoinducer Synthesis

LuxI, transcribed when LuxR forms a complex with AHL

LuxR

acts as signal sensor and transcription factor, bind to AHL then DNA, in cytoplasm.

Gm+ Quorum Sensing Signal

peptide (binds to sensor histidine kinase, creates HTH, response regulator phosphorylated)

Gm+ signal transport

ABC transport

Lactonase

cleaves lactone ring of AHL

Furanone

blocks the formation of biofilms

Anaerobic Response to Oxidative Stress

superoxide reductase (makes hyd. peroxide) → peroxidase

Aerobic Response to Oxidative Stress

superoxide dismustase (makes hyd. peroxide) —> catalase

Superoxide Present

SoxR (transcription factor) → SoxS (transcription factor) → SodA encodes sup. dismutase & nFO endcodes for endonuclease (DNA repair)

Glutathinone

tripeptide, senses RED/OX state of cytoplasm

forms a disulfide bond and bonds with a molecule when under stress conditions, kefB/C antiporter activated to acidify cytoplasm, detoxifies ROS

Hydrogen Peroxide Present

OxyR → gorA → Glutathianone reductase

σ32 + chaperone proteins

universal heat shock response

mRNA unfolds, activates σ factor involved, makes chaperones (refold proteins and regulate σ) and proteases (degrade what cannot be saved)

σ24E + RseA

extreme temperature/ stress response

heat denatures outer membrane protein, degrades inner membrane protein to release σ, transcribes cell envelope repair proteins

Spore Properties

SASP (aid in resistance), dehydrated, NO metabolic activity, restive layers (spore coat, etc.)

Spo0A

master regulator of spore formation, activated via phosphorelay

activates endospore formation, turns off gene inhibition

σ-factor regulation of spore formation

Mother Cell σ factors

E → K, must be modified before active

Forespore σ factors

F → G, must remove anti σ-factor

Germination

occurs when spores sense nutrients → water enters, cortex breaks, and vegetative growth resumes

EPS Matrix

found in biofilms

adherence, prevent dehydration, provide protection

eDNA

extracellular DNA

promotes HGT, help increase antibiotic resistance

NOSTOC cell differentiation

practices nitrogen fixation

no more RubisCO, no pigments, no PS II; glutamine and nitrogenase expressed, obtain sugar from neighbors

Streptomyces

germ tube grows into substrate then aerial hyphae forms

Myxococcus and Fruiting Body Formation

Swarm (group feeding, type A motility) → aggregate → Mound forms → Myxospores and Peripheral Rod Cells → Myxospores released → become vegetative cells again

FruA(-P)

induces early gene development, encourages aggregation and sporulation

Signaling Fruiting Body Formation

starvation → PPGTP → protease (exported) → A-Signal → 2 comp. reg → FruA-P

C-Signal

cell surface signal, cell density

binds to surface → Kinase → FruA-P

A-Motility (Myxococcus)

gliding motility (slime trails), single cells at edge of colony

S-Motility (Myxococcus)

social, group movement of cells, mediated by type IV pili

Swarmer Cells

C. Crescentus

no cell division, motile, high conc. of CtrA-P, colonizers

Stalked Cells

C. Cresentus

attach to surface w/ Holdfast, high cell division, low conc. of CtrA-P