bacterial secretions and toxins

Question 1

what is the function of bacterial protein secretions

Answer 1

• interact with environment eg. motility, nutrient acquisition, intercellular communication, toxin secretion, adhesion, degradation

Question 2

how do bacteria secrete proteins

Answer 2

DNA encoding of transport mechanism - genome
- mobile elements - transposons, plasmids pathogenicity islands and phages

Question 3

what membranes do gram negative bacteria have

Answer 3

inner and outer membrane

Question 4

what membranes do gram positive bacteria have

Answer 4

only inner membrane

Question 5

what are the types of bacteria secretion systems

Answer 5

• sec system
• tat system
• type 1-7 secretion system

Question 6

what is the sec system

Answer 6

general secretion system for unfolded proteins

Question 7

what is the tat system

Answer 7

twin-arginine translocation system for folded proteins

Question 8

what is the type 1-7 secretion system

Answer 8

different types of secretion systems in gram negative and positive bacteria

Question 9

describe the sec secretion pathway

Answer 9

• highly conserved
• sec Y, sec E and sec G

Question 10

describe co translational translocation in the sec pathway

Answer 10

• co translation translocation
• requires SRP and ribosome

Question 11

describe post translational translocation in the sec pathway

Answer 11

requires sec A and ATP

Question 12

what is an example of type VII transport

Answer 12

• gram positive mycobacterium
• ATP hydrolysis drives conformational changes to open channel

Question 13

what types of protein secretion transports across outer membrane

Answer 13

type 3, 4 and 6

Question 14

what type of secretion pathway is a auto transporter family

Answer 14

type 5

Question 15

what secretary pathways do gram negative bacteria do

Answer 15

• across inner membrane
• type 2, 5a,5b,5c,5d,5e,5f

Question 16

what does type 5a transport systems use

Answer 16

classic autotransporter

Question 17

what does type 5b secretary system use

Answer 17

two partner system

Question 18

what does type 5c secretory system use

Answer 18

trimeric autotransporer adhesins

Question 19

what does type 5d secretory systems use

Answer 19

type a/b hybrid

Question 20

what does type 5e secretary systems use

Answer 20

inverse autotransporters

Question 21

what secretary systems transport across both membranes simultaneously

Answer 21

type 1, 3, 4 and 6

Question 22

what does type 3 secretary pathways use

Answer 22

injection - share flagellin components

Question 23

what does type 4 secretary pathways use

Answer 23

pilus assembly and injection - protein and DNA

Question 24

what does type 6 secretary pathways use

Answer 24

injection

Question 25

what viruses use type 6 secretory pathways

Answer 25

- Vibrio cholerae - Edwardsiella tarda - Pseudomonas aeruginosa - Francisella tularensis and plant pathogens

Question 26

how do toxins cause disease

Answer 26

- damage cell membranes - disrupt protein synthesis - inhibit neurotransmitters - activate immune system

Question 27

how do virulence factors help bacteria

Answer 27

to survive in host and pass on to new host - classified into endotoxins and exotoxins

Question 28

what are exotoxins

Answer 28

- secreted from bacteria - heat sensitive soluble proteins

Question 29

what are the main types of exotoxins

Answer 29

- surface activated - bind surface receptors - enzymes - membranę/ tissue damage - pore forming - intracellular

Question 30

what diseases do exotoxins cause

Answer 30

- gas gangrene - scarlet fever - diphtheria - botulism - tetanus - antibiotic associated diarrhoea - scalded skin syndrome

Question 31

how do surface activated exotoxins work

Answer 31

eg. superantigens 1) bind to T-receptors to major histocompatibility complex class 2 (MHC 2) 2) stimulates the host T cells to create cytokine storm 3) inflammation and tissue damage, fever, shock and rash

Question 32

what are the enzyme exotoxins

Answer 32

- phospholipase - nucleases - proteases - glycohyrolases

Question 33

what bacteria makes phospholipase c

Answer 33

bacillus anthracis

Question 34

how does phospholipase cause disease

Answer 34

- degrade bilayer of host cell - cellular lysis - degrade phagosomes to enter cytoplasm

Question 35

what bacteria produces DNase

Answer 35

staphylococcus aureus

Question 36

how do nucleases cause disease

Answer 36

- degrade DNA released from dead cells - allow bacteria to move

Question 37

how does proteases cause disease

Answer 37

- degrade connective tissue - tissue invasion

Question 38

what bacteria produce collagenase

Answer 38

clostridium perfringens

Question 39

how do glycohyrolases cause disease

Answer 39

- degrade connective tissue - tissue invasion

Question 40

what bacteria produces hyaluronidase

Answer 40

staphylococcus aureus

Question 41

what enzymes do clostridium perfringens create

Answer 41

- opportunistic pathogen - phospholipase C, collagenase, protease and hyaluronidase - several toxins - by product - acid and gas

Question 42

what enzymes do staphylococci produce

Answer 42

lipases, hyaluronidase, streptokinases, DNases, fibrinolysin, streptolysin S and O

Question 43

what do pore forming toxins cause

Answer 43

- osmotic lysis - infiltration

Question 44

what are the characteristics of listeriolysin O toxins (LLO)

Answer 44

- cholesterol receptor - 35nm pores - k+ efflux and Ca 2+ influx

Question 45

what are exotoxins recognised by

Answer 45

pattern recognition receptors

Question 46

what mainly secretes lipopolysaccharides

Answer 46

gram negative bacteria

Question 47

how do lipopolysaccharides cause disease

Answer 47

lipid A- toxic component causing inflammation and fever polysaccharide containing core glycoprotein and O-antigen

Question 48

where do lipopolysaccharides bind to

Answer 48

CD14 and TLR4 receptors

Question 49

what are AB toxins made from

Answer 49

B subunit - binding/ host recognition A subunit - enzyme activity

Question 50

what are the targets of AB toxins

Answer 50

- ribosomes - transport mechanisms - intracellular signalling - CAMP production

Question 51

what are the effects of AB toxins

Answer 51

- diarrhoea - loss of neuronal function - death

Question 52

what produces AB toxins

Answer 52

- diphtheria - cholera - botulinum - tetanus toxins

Question 53

what affect to AB toxins have on muscles

Answer 53

- effects on nerve-muscle transmission causing muscle spasms and blocks contraction

Question 54

what does bacillus anthracis cause

Answer 54

skin infections - anthrax toxin is multi component AB toxin and pore