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Micr 221 > Midterm 2 > Flashcards

Midterm 2 Flashcards

1
Q

Main difference gram neg vs positive

A

Neg has outer membrane

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2
Q

Cytoplasmic membrane has what

A
  • lipid bilayer
  • semi permeable barrier
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3
Q

What determines the lipid composition of cytoplasmic membrane

A

Conditions
Ie. temperature

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4
Q

Functions of membrane proteins

A
  • transporters
  • signal transduction
  • energy transduction
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5
Q

Energy transduction example

A

Electron transport chain

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6
Q

How do bacteria survive hypotonic conditions

A

Peptidoglycan stretches with pressure and prevents lysis
- porous = allows transport

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7
Q

How do bacteria survive pep degradation

A

Isotonic condition
- lose shape
- still stable

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8
Q

Spheroplasts

A

Gram negative without pep

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9
Q

Protoplasts

A

Gram pos without pep

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10
Q

How do mycoplasmas survive without cell wall

A

Uses sterols from host to stabilize membrane

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11
Q

Why is pep a good antibiotics target

A

Not made by humans
On outside of cell
Made by most bacteria

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12
Q

How does bacitracin target pep

A

Binds undecaprenyl, prevents dephosphorylation = no phosphate = no binding

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13
Q

How do beta lactams target pep

A

PBP transpeptidase = no cross linking = weakened Pep = lysis

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14
Q

Pep structure

A

Glycan backbone
NAM
NAG

NAM has peptide chain

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15
Q

Making pep

A
  1. UDP binds NAG
  2. Some convert to NAM
  3. L - ala + alanine racemase = D-ala ( 1 unit)
  4. D-Ala d-ala ligand makes D-Ala D-ala (2 units)
  5. MurF adds d-ala and other peptides to NAM
  6. NAM binds to undercaprenyl phosphate
  7. Gets phosphate, loses UDP [ LIPID 1]
  8. NAG binds NAM
  9. Get second phosphate [LIPID 2]
  10. Flips to periplasm
  11. Penicilin binding proteins add lipid 2 to chain
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16
Q

What does undercaprenyl phosphate do

A

Provides phosphate groups to detach UDP and attach NAG

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17
Q

What does cycloserine do

A

Blocks alanine racemase = no d-ala = incomplete chain

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18
Q

Undecaprenol recycling

A

Flips between periplasm and cytoplasm depending on number of phosphates

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19
Q

Lysozyme is part of what immune system

A

Innate

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20
Q

Where is lysozyme

A

Saliva tears milk mucous

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21
Q

What does lysozyme do

A

Cleaved NAG-NAM bond
Therefore weakens cell wall

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22
Q

Why is lysozyme more effective on gram pos

A

Pep more exposed
No outer membrane

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23
Q

Order of pentapeptides in pep

A

L-alanine
D-isoglutamate
Diamino acid
D-ala
D-ala

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24
Q

Cross linking pep gram neg

A

3 and 4
Release terminal d-ala

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25
Q

Cross linking gram pos

A

Interpeptide bridge between diamino and first d-ala

Terminal d-ala released

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26
Q

How are cross links formed

A

PBP transpeptidase

  1. Forms complex w peptide
  2. Diamino reacts
  3. Amide bond forms
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27
Q

What are b lactamases

A

Enzymes degrade b lactams
Resistance mechanism

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28
Q

Serine b lactamases

A

Serine binds to lactam = hydrolysis = inactive lactam

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29
Q

B lactamases inhibitors

A

Co prescribed with b lactams

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30
Q

MRSA and b lactam resistance

A

Has a PBP gene resistant to lactams
[active site blocked until bound to PB]

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31
Q

How does vancomycin target pep

A

Only targets gram pos
Binds to d-ala d-ala = blocks PBP

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32
Q

Vancomycin resistance

A

Replaces d-ala with different d amino acids = vanomycin cant bind

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33
Q

Gram neg outer membrane

A

Outer leaflet and inner leaflet

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34
Q

Gram neg outer leaflet

A

Lipopolysaccharide (LPS) only in negs

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35
Q

Inner leaflet gram neg

A

Phospholipids

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36
Q

LPS function

A

Impermeable

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37
Q

LPS traits

A
  • neg charged
  • amphipathic
  • bulky
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38
Q

LPS structure

A

Lipid a
Core polysaccharides
O antigen

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39
Q

Lipid A (LPS) function

A

Anchors LPS to membrane

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40
Q

Lipid A (LPS) structure

A

Sugars with fatty acids
Phosphorylation = negative charge

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41
Q

Lipid A (LPS) toxicity

A

Releases endotoxin when lysed
Fever inflammation, septic shock

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42
Q

Core poly (LPS) function

A

Links lipid A to O antigen

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43
Q

Core poly (LPS) structure

A

Sugars
Branches
Anionic sugar
Neg charge

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44
Q

O antigen (LPS) function

A

Classification
Antigenic (bacteria changes this to avoid immune response)

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45
Q

Divalent cations Outer membrane gram negative

A

Stabilize
Bridge LPS molecules
Neutralizes electric repulsion

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46
Q

Gram neg outer membrane function

A

Barrier
Prevent antibiotics
Prevents degradation enzymes (too large to pass)
Resistant to detergents

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47
Q

Why are gram negs resistant to detergent

A

Outer membrane - LPS
Steric and charge

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48
Q

What are divalent cations needed for LPS

A

Cross-bridging adjacent LPS molecules

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49
Q

What happens limited Mg LPS

A

Lipid A may be changed to 4AA to cross bridge

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50
Q

Colistin

A

Cationic antibiotic
Binds to lipid A phosphate groups
Lipid tail can permeate membrane

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51
Q

How do Mg levels impact colistin

A

Mg sensitive to colistin
4AA prevents colistin binding = resistance

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52
Q

MCR-1 gene

A

Colistin resistance gene - HGT
Binds smth = positive charge = repels cation colistin

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53
Q

Outer membrane proteins gram negative

A

Lipoproteins
B barrel proteins

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54
Q

Porins

A

Nutrient intake gram neg
Form channels
B barrel
Water filled center = selectivity

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55
Q

Outer membrane assembly gram negative

A

LPS assembled in cytoplasm but needs to cross to periplasm
- chargers make it hard
- LPT proteins make LPT pathway
- LPTD guides it through

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56
Q

Vesiculation

A

Vesicles can form when outer membrane of gram negative not attacked to pep

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57
Q

Brauns lipoprotein

A

Fatty acid chain embedded in outer membrane gram neg
COVALENTLY BOUND TO PEP

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58
Q

Teichoic acids are in what

A

Gram pos cell wall

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59
Q

Teichoic acids

A

Linear polymers - glycerol or ribitol
- may have substituents (pos charged)
Phosphate groups neg charged

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60
Q

2 Teichoic acids

A

Wall Teichoic acids (WTA)
Lipteichoic acid (LTA)

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61
Q

Wall Teichoic acid

A

Attached to NAM or peptide in pep
Extends beyond pep surface to environment
Starts within pep

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62
Q

Lipoteichoic acid

A

Attached to lipids in cytoplasmic membrane
Extends through pep to environment

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63
Q

Teichoic acids function

A
  • anchor wall to cytoplasm membrane
  • binds cations = less repulsion
  • regulation of pep degredation during division
  • d-ala protects antibiotics and immune
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64
Q

Teichoic acids infections

A

Pathogensis
- biolfilm
- colonization
- inflammation upon release

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65
Q

Mycobacteria staining

A

Acid fast staining
Heat cells with stain

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66
Q

Mycobacterial cell wall

A

Gram pos but have outer membrane
- mycolic acids not LPS

Arabinogalactan
- sugar polymers

Pep

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67
Q

Mycobacteria outer membrane

A

Asymmetrical bilayer
- inner = mycolic acids
- Outer = glycolipids

Hydrophobic + impermeable

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68
Q

Cells need what 3 things

A

Energy electrons carbon

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69
Q

Heterotrophs

A

Organic molecules for carbon

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70
Q

Autotrophs

A

CO2 for carbon source

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71
Q

Reducing power

A

Electrons

Needed for
- anabolic reactions
- making atp

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72
Q

Organotrophs

A

Reduce organic molecules

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73
Q

Lithotrophs

A

Reduced inorganic molecules

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74
Q

Chemoorganoheterotrophs

A

Chemo = energy not from light
Organo = reduced organic molecules for electrons
Hetero= organic source of carbon

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75
Q

Most bacteria are what metabolic classification

A

Chemoorganoheterotrophs

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76
Q

How do Chemoorganoheterotrophs make atp

A

Oxidizing organic molecules
- aerobic
- anaerobic
- fermentation

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77
Q

Aerobic respiration

A

When there is adequate oxygen

Glycolysis : glucose —> acetyl coA
Krebs cycle: acetyl coA —> ATP, NADH, FADH2
ETC: NADH/FADH2 —> ATP

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78
Q

Glycolysic pathways

A

Embden-Meyehof (EM): most common, ATP NADH, G3P —> PYRUVATE

Entner-Douforoff (ED): some bacteria, NADPH, glucose —> pyruvate + G3P (—> EM)

Penrose phosphate pathway (PPP): biosynthesis, precursor aminos , NADPH

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79
Q

Kerbs cycle

A

Acetyl coA —> CO2 + GTP, NADH, FADH2

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80
Q

ETC

A

Membrane bound electron carriers: Ubiquinone (coenzyme Q) and cytochromes

Carriers reduced via oxidation

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81
Q

ETC in E. coli

A
  • NADH electrons via ubiquinone
  • pass through cytochromes
  • to terminal electron acceptor (O2)
  • proteins to periplasm = proton motive force (PMF)
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82
Q

Proton motive force + ATP synthase

A

Proton gradient
- cytoplasm = neg
- protons flow from periplasm to cytoplasm via atp synthase

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83
Q

Anaerobic respiration

A
  1. Glycolysis
  2. Krebs cycle
  3. ETC

** terminal electron receptor is not O2
Could be nitrate, surface, CO2 etc
Ex. NO2- —> NO —> 2NO —> N2O —> N2

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84
Q

Fermentation

A

When lacking or repressing ETC
- No ETC = still have NAHD

Fermentation = NADH —> pyruvate + NAH+. —> new products
Ex. Ethanol, lactic acid, CO2

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85
Q

Why is it hard to target metabolic activity of bacteria

A

Most bacteria = Chemoorganoheterotrophs
Humans = Chemoheterotrophs

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86
Q

Tetrahydrofolate

A

Co factor needed to make purines and pyrimidines and methionine

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87
Q

Importance of tetrahydrofolate antibiotics

A

Bacteria must produce it
Humans must eat it

Bio synthetic enzymes = targets

88
Q

Sulfa drugs

A

Inhibits dihydropteroate synthase (early precursor to tetrahydrofolate)

Competitive inhibitor

89
Q

Trimethoprim

A

Inhibits dihydrofolate (can’t reduce to become tri)

90
Q

Passive diffusion

A

Moves with gradient across membrane

91
Q

Facilitates diffusion

A

Transport proteins aid in transportation across barrier in vesicle like manner

92
Q

Active transport

A

Against gradient, needs energy

93
Q

Primary active transporters

A

Use ATP to transport against gradient

94
Q

ATP binding cassette transporters (ABC)

A

Primary active transporters in bacteria

Import and export

95
Q

Solute binding proteins

A

Work with most ABCs
- deliver specific substrate to transported

96
Q

Where are SBPs in gram neg

A

Periplasm

97
Q

Where are SBPs in gram pos

A

Lipoprotein or pep

98
Q

Secondary active transport

A

Ion gradient potential energy transports against gradient
- ETC
- V type ATPase
- Antiporter

99
Q

V type ATP ase

A

Reverse of ATP synthase - uses ATP to send them against

100
Q

Antiporter

A

ETC generated proton motive force (PMF)
H+ down gradient powers Na+ up gradient
Na+ gradient can then power symporter

101
Q

Group Translocation

A

Active transport with modification of substrate

102
Q

Phosphotransferase system (PTS)

A

Group translocation
- sugar across cytoplasm membrane
- sugar phosphorylated during transport
- P from PEP —> PTS —> sugar

103
Q

Outer membrane transport porins types

A

General
Substrate specific

B barrel proteins

104
Q

General porins

A

Channel size = which substrates can enter

105
Q

Substrate specific porins

A

Binding site attracts substrate, size impacts selectivity

106
Q

Ton B dependent receptors

A
  1. Receptor inhibited
  2. Binding to receptor
  3. Exposes ton B box
  4. Box binds to Ton B
  5. Ton B removes plug from receptor
107
Q

Why do bacteria need iron

A

Cytochromes and enzyme co factors

108
Q

How do bacteria find iron

A

Siderophores

109
Q

Siderophores

A
  1. Bacteria secretes Siderophores
  2. Bind to Fe3+
  3. TonB receptor transports into periplasm
  4. Binds to SBP
  5. To ABC
  6. To cytoplasm
110
Q

Positive taxis

A

Move toward stimulus

111
Q

Negative stimulus

A

Move away from stimulus

112
Q

Chemotaxis

A

Move away/towards attractants or repellents

113
Q

Flagellar swimming

A

Rapid rotation of flagella to move in liquid environments

114
Q

Atrichous

A

No flagella

115
Q

Monotrichous

A

Flagella on one end

116
Q

Lophotrichous

A

Multiple flagella at one or both ends

117
Q

Amphitrichous

A

One flagella at both ends

118
Q

Peritrchous

A

Flagella all over

119
Q

Flagella structure

A

Basal body
Filament
Hook

120
Q

Basal body

A

Attaches flagellum to cell envelope
Has motor

121
Q

Filament - flagellum

A

Helical extending from cell
Rotation moves cell

122
Q

Hook - flagellum

A

Transmits rotation from basal body to filament

123
Q

Basal body structure

A

Protein structure - central rod
Rings - L,P,MS,C

124
Q

Basal body function

A

Export subunits during assembly
Rotate hook and filament

125
Q

basal body motor

A

Rotation powered by PMF
Switch determines direction ( C ring in cytoplasm)

126
Q

Flagella + innate immune

A

on surface = target
Flagellin = toll like receptor 5 (TLR5)
Flagellin binds TLR5
Activates transcription factor
Pro inflammatory cytokines produces

127
Q

Flagella adaptive immune system

A

Antigenic structure

128
Q

Immune evasion flagella

A
  • alternate flagellins = phase variation
  • stop producing once in host
129
Q

Direction of flagellum rotation determines what

A

Run vs tumble

130
Q

Monotrichous and peritrichous flagellum direction

A

Run = counter clock
Tumble = clockwise

131
Q

Methyl accepting chemotaxis proteins (MCPs)

A

Chemoreceptors in cyto membrane
Diff ones sense diff attractants or repellents
Change direction of flagella

132
Q

How do MCPs direct bacteria

A

MCP ligand binding domain + ligand = domain
Ligand changed shape of domain
CheW bound to domain
Activity changes based on ligand

133
Q

Tumble no ligand

A
  1. CheW detects no attraction
  2. CheW causes CheA to auto phosphorylate
  3. CheA phosphorylates CheY
  4. CheY binds to switch, changes direction to CW
  5. CheZ dephosphorylates CheY and direction —> CCW
134
Q

No tumble, ligand

A
  1. CheW detects
  2. Does not cause auto phosphorylation

Therefore no switch

135
Q

Excitation flagellum

A

Threshold must be met among many MCPs to determine how long direction will stay same or change

136
Q

adaptation

A

After ligand binds:
MCP methylated by CheR
Increases CheA phosp
Increases amount of CheY

  • removes CCW bias
137
Q

Temporal gradients

A

Bacteria measure [] gradients for chemotaxis

Current = number of MCPs with ligands
Past = number of methylated MCPs

Allows bacteria to swim through gradient

138
Q

What direction is swimming if Ligand [] increases

A

Swimming up

More ligands = more methylation (BUT DELAYED) = CCW bias

Fewer tumbles

139
Q

What direction swimming if ligand [] decreasing

A

Down gradient

Less ligands = methylation SAME OR MORE = more tumbles

140
Q

What causes MCP demethylation

A

CheB over time

141
Q

What would happen if MCP did not demethylate

A

More binding wouldn’t equal CCW bias

142
Q

Swarming motility

A

Flagella moving on surfaces

  • coordinated movement
  • requires multiple flagella and surfactants to reduce surface tension
143
Q

Twitching motility

A

Pilli - moving on
Inches like catapilar

Extends: adds subunits to base (pillins)
Adheres
Retraction
Pillins removed

Colonize new environments

144
Q

Glycocalyx

A

Polysaccharide layer around cell
Adherence
Related to EPS in biol films

Slime layer - easily remove from cell
Capsule - attached to cell

145
Q

Capsule

A

Negative staining
Long polymers
Covalent bonding

146
Q

Capsular polysaccharides

A

Repeating sugar subunits

147
Q

Capsule functions

A

Adherence
Protection
- desiccation
- engulfment
- phage
- antibiotics

148
Q

Major contributor to serum resistance

A

Capsule

149
Q

Serum resistance

A

Ability to survive and spread in blood

150
Q

How do capsules protect from antigens

A

Similar to host cell sugars
Mask antigen components

151
Q

Conjunctive vaccines

A

Capsule polysach attached to immunogenicity protein carrier

  • modified to evoke immune response
152
Q

Capsule assembly gram positive

A
  • Components transported to surface
  • sugars activated by UDP
  • transferred to undecaprenyl phosphate
  • grows chain
  • flipped to extracellular
  • polymerized
  • attached to surface
153
Q

Capsule assemble gram negative methods

A
  • Wzx-Wzx dependent pathway
  • ABC transporter dependent pathway
154
Q

Wzx Wzy pathway

A
  • subunit assembled in cytoplasm
  • flipped by Wzx
  • polymerized by Wzy
  • Translocated via Wza channel
  • incorporated on cell surface
155
Q

ABC transporter dependent pathway

A
  • full polysaccharide made in cytoplasm
  • transferrred to surface via ABC transporters
156
Q

Non flagellar appendages

A

Pilli

157
Q

Types of pilli

A

Type IV secretion pilli
Type IV pilli
Type III secretion systems
Chaperone-usher pilli

158
Q

Type 4 secretion pilli

A

Sex pilli; conjugation

159
Q

Type 4 pilli

A

Twitching motility

160
Q

Chaperone usher pilli

A

Virulence factors - adhesion

161
Q

Parts of chaperone usher pilli

A

Rod: major pillins
Fibrillum: minor pillins attach end adhesion to rod

162
Q

Pilli pathogensis

A

Can only bind to specific molecules depending on the bacteria

163
Q

UPEC (uropathogenic E. coli)

A

Causes most UTIs
Type 1 pilli attch to proteins in uroepithelial cells
Forms intracellular bacterial communities

164
Q

UPEC and pyelonephritis

A

UPEC —> uterus —> kidneys

Must down regulate T1P production
Increase P pillus production

165
Q

Immune response to pilli

A

Targeted
Can be used to make vaccines

166
Q

How can pilli be used to make vaccine

A

Purify adhesions
Generate antibodies
Binds to adhesions
Prevents attachment

167
Q

Antigenic variation

A

Change of pilli structure to evade immune response

168
Q

P pilli assembly

A
  • subunits —> periplasm via general sec system
  • PapD binds subunits
  • Helps them fold (chaperone)
  • delivers to PapC
  • PapC forms base
  • Translocated subunits to surface (Usher)
  • PapA (major pillins) Translocated via PapC
169
Q

What happens if a cell doesn’t;t have PapA gene

A

PapA=major pillins

No major pillins = no rod on pilli

No rod = no pillus

Sill has base and adhesion

Therefore still adherent

170
Q

Regulation of Pilus length

A
  • PapH attaches pillus to cell
  • also regulates addition of PapA
171
Q

What happens if cell doesn’t have papH gene

A

PapH = attached pillus to cell and regulates addition of PapA

no PapH = long pilli not attached to cell

172
Q

What happens if too much papH

A

Short pilli ( PapA can’t be added enough)

173
Q

Gram positive pilli

A

Adhesion
Biofilm formations

174
Q

Gram positive structure of pilli

A

Base Pillin attached to pep
Subunits covalently bonded
Adhesions at end
Long and flexible and thin

175
Q

Gram positive Pilli assembly

A
  • subunits contain cell wall sorting signal (pos charge) LPXTG
  • subunits transported via general Sec system
  • adhesion folds in periplasm and attaches to subunit
  • sortase recognizes signal
  • removes signal LPXTG
  • sortase binds to subunits and forms complex
  • pillus specific sortases form polymers of subunits via covalent bonds
  • house keeping sortase trasfers pilli to lipid II
  • incorporated into Pep by PBPs
176
Q

Exotoxins

A

Proteins secreted by pathogens

Lead to injection

Disruption host cells

177
Q

Groups of exotoxins

A

AB toxins
Pore forming toxins
Superantigens

178
Q

AB toxins

A

Interfere with internal processes of host cells

179
Q

Structure of AB toxins

A

A: active component
B: binding component

Form complex

B binds to receptor on host
Triggers endocytosis of host cell
Allows A to enter host

A = enzyme for making toxic compounds

180
Q

Diphtheria

A

AB toxin

Cardiac and nervous tissue

A blocks elongation factor = no translation

=no proteins

181
Q

Shiga toxin (Stx)

A

From type of E. coli

Severe inflammation and GI bleeding

Has prophage

AB toxin

A: removed nucleobase from rRNA = disabled ribosome

Vascular

182
Q

Pore forming toxins

A

forms channels in host membrane
=no gradients = cell swells = cell lyses

183
Q

Hemolysins

A

Pore forming toxin
Lyses red blood cells
Bacteria steal iron released

184
Q

How do pore forming toxins help bacteria escape phagosomes

A

Phagosome engulfs
Toxin released
Cell lysed
Can replicate in immune cells
Spreads through blood

185
Q

Superantigens

A

Force binding of immune cells even when no antigen

=Overproduction of proinflammatory cytokines
= fever, organ failure

Ex. Staphylococcus aureus toxic shock syndrome toxin

186
Q

Sec system - post translational translocation

A

Chaperons stabilize
Sec A binds signal peptide
Escorts to SecYEG (channel)
Uses ATP

187
Q

Sec system: periplasmic proteins

A

Signal peptidase recognizes and cuts signal peptide
Chaperones help protein fold in periplasm

188
Q

TAT system

A

Used when proteins can’t be folded in periplasm

Translocated folded proteins

  • protein folds in cytoplasm
  • TatABC targets via signal peptide
  • Translocation via PMF
  • Signal peptide cleaved off
189
Q

ABC exporters

A

Recognize signal protein
Cleave it off during export

190
Q

Sec system - importing proteins to membrane

A
  • signal peptide translated
  • recognized by signal recognition particle
  • translation stopped
  • escorted to SecYEG
  • translation continues into membrane
191
Q

Gram negative BAM complex

A
  • B barrel proteins targeted to outer membrane
  • Sec system Translocates
  • chaperones fold
  • delivered to B barrel assembly machinery
  • inserted into membrane
192
Q

Gram neg secretion systems

A

Transport proteins out of cell

193
Q

Type 5 secretion system (T5SS)

A

Tat or Sec
Protein Translocated via B barrel
**protein stays attached to cell (channel)

194
Q

Type 1 secretion system (T1SS)

A

ABC transporter
Membrane fusion protein
B barrel

Steps

195
Q

Type 3 secretion system (T3SS)

A

Inject proteins into eukaryotic cells
Substrates = effector proteins

Bacterial cytoplasm —> cytoplasm of host cell

Manipulate host structure and function
Colonization

196
Q

T3SS structure

A

> 20 proteins
Basal body
Needle

197
Q

T3SS assembly

A

Subunits —> hollow central channel —> extracellular
Plug blocks channel after assembly

198
Q

T3SS effectors

A

Binds target
Channel opens
Chaperones bring unfolded effectors to T3SS
Effector travels through T3SS
Folds in target

199
Q

T3SS effector proteins

A

Target host cytoskeleton + signal transduction
Rearrange cytoskeleton of epithelial cells
Forms ruffles on surface
Allows bacteria to enter NON-PHAGOCYTIC cells

200
Q

Protein secretion gram positive

A

Sec or tat
Sortase = attaches proteins to surface
Virulence factor
Nutrient acquisition
Immune evasion

201
Q

Direct interactions with regulators

A

Stimuli directly affects transcription
Ex. Lac operon

202
Q

2 component signal transduction systems (TCSs) parts

A

Sensing + response : different proteins

Sensor kinase: membrane protein
Response regulator: cytoplasmic DNA binding protein

203
Q

TCSs steps

A

Stimulus
Activates sensor kinase
Kinase auto phosphorylated
Phosphate transferred to response regulator
Phosphorylation changes regulated structure
Can bind to DNA and change transcription

204
Q

How is enterococci resistant to vanomycin

A

Vanomycin: targets d-ala d-ala

Enterococci senses vancomycin
Changed d-amino to avoid vancomycin targeting

Done only when present because fitness cost

205
Q

Agrobacterium tumefaciens

A

Plant pathogen
Causes tumour-like growths
Carry tumour inducing plasmid

  • enters plant through surface wound
  • sensed plant via TCSs (sensor kinase detects)
  • response regulator phosphorylated
  • Transfer part of plasmid to plant cells
  • Transcribed in host plant
  • encode type 4 secretion system (pilli)
  • connects cells
  • proteins transfer dna from plasmid
  • T4SS secretes dna into plant
  • dna enters plant dna and integrates
  • plant cell transcribes dna
  • makes phytohormones (forms tumours)
  • Makes opines (makes nutrient for bacteria)
206
Q

A tumefaciens uses in bioengineering

A

Prepare Ti plasmid in lab with desired genes, remove tumour genes
Transfer to plant
Changes plant properties

207
Q

Phosphorelays

A

More complex version of TCSs
Phosphate transfer protein to protein
More than 2 proteins = more regulation

208
Q

Sporulation Phosphorelays

A

Endospore formation highly regulated
Each step controlled via different factors
Ensures formation only when necessary
Irreversible once started

209
Q

When does sensing not impact transcription

A

MCPs
Only alters direction

210
Q

Quorum sensing

A

Sense population density
High enough = change gene expression (ie make biofilm)

211
Q

Quorum sensing functions

A

Virulence factor production
Biofilm formation
Competence

212
Q

Autoinducers

A

Signalling molecules
Enough = enough cells to express

213
Q

QS and luminescence high cell density

A

Proteins from lux operon —> light
Regulated by LuxI and LuxR
High cell denisity = high [] autoinducers
AI bind luxR
LuxR binds promoter
Recruits RNAP
Lux proteins produced
Cells emit light

214
Q

QS luminescence low density

A

Low [] AIs
Won’t bind LuxR
Won’t bind promoter
No transcription
No light

215
Q

QS and EHEC

A

Genome has pathogenicity island
Encodes T3SS
Effector secreted into host cells
Bin to protein on EHEC surface
Remodels host cytoskeleton
Releases Shiga toxin

Regulated via TCS

216
Q

Probiotics and EHEC

A

QS = potential anti virulence factor
Probiotics contain Lactobacillus spp
That can interfere with EHEC AIs

Micr 221 (3 decks)

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