Bacteriocins

Question 1

Genes that code for nisin

Answer 1

1. nisA codes for the prepeptide
2. nisB, nisC code for modifications
3. and nisT, responsible for nisin transport.

Question 2

Genes that code for colicin

Answer 2

1. cea codes for colicin E1
2. cei codes for colicin immunity. protecting the producer
3. cel codes for protein lysis which releases colicin.

Question 3

Genes that code for Plantaricin A

Answer 3

1. plnA encodes plantaricin peptide
2. plnEF and plnJK code the complementary synergenic peptides
3. plnC is a response-mediated regulator of plantaricin.

Question 4

Bacteriocin

Answer 4

A antimicrobial peptide synthesized by bacteria to inhibit or kill closely related strains, eliminating competition.

Question 5

Location of bacteriocin genes

Answer 5

Majority on plasmids, rarely on chromosomal.

Question 6

Classes of bacteriocins

Answer 6

Class I. Lantibiotics
Class II. non-Lantibiotics
Class III. Heat Labile bacteriocins
Class IV. Complex bacteriocins

Question 7

Class I properties

Answer 7

<5kDa, extensive PTMs, created using lanthionine and methyllanthione, 2 types

Question 8

Type A lantibiotics

Answer 8

Linear, amphillic, pore-forming.

Question 9

Example of Lantibiotic Type A

Answer 9

Nisin, produced by lactococcus lactis, disrupts gram positive bacterial binding of lipid II.

Question 10

Type B lantibiotics

Answer 10

Compact, enzyme inhibiting.

Question 11

Example of Lantibiotic type B

Answer 11

Subtilin, produced by bacillus subtilis, inhibits cell wall synthesis, by stopping lipid polymerization by enzyme transglycosylase.

Question 12

Class II properties

Answer 12

<10kDa, heat stable, few PTMs, 3 types.

Question 13

Class IIa

Answer 13

Pediocins, affect gram positive bacteria by inhibiting enzymes.

Question 14

Class IIa example

Answer 14

Pediocin PA-1, produced by pediococcus acidalacticum, inhibits mannose phospho transferase.

Question 15

Class IIb

Answer 15

Two-peptide system, cooperation of 2 subunits to form pores.

Question 16

Class IIb example

Answer 16

Lactococcin G, attacks simple membranes.

Question 17

Class IIc

Answer 17

Inhibit sec secretion pathways,

Question 18

Class IIc example

Answer 18

Mesentrecin YIO5, produced by Leuconostoc mesenteroides.

Question 19

Class IId

Answer 19

Single-peptide attacks, but vary greatly.

Question 20

Class III

Answer 20

> 30kDa, enzymatic degradation of bacterial components.

Question 21

Class III example

Answer 21

Lysostaphin, produced by lysostaphium, cleaves peptidoglycan in strepococcus sp.,

Question 22

Class IV

Answer 22

Complex bacteriocins requiring lipids or carbohydrates for activation.

Question 23

Class IV example

Answer 23

Colicin, produced by escherichia coli, target gram negative bacteria pathways.

Question 24

Effects of bacteriocins on gram positve bacteria

Answer 24

Single peptidoglycan layer makes them susceptible, pores are formed in the membrane, leading to cytoplasm leakage and cell death.

Question 25

Examples for gram positive bacteria

Answer 25

1. Nisin II binds to lipid II forming pores in peptidoglycan layer.

Question 26

Effects of bacteriocins on gram negative bacteria.

Answer 26

Generally more resisitant, generally receptor related and then enzyme degradation.

Question 27

Example for gram negative bacteriocin

Answer 27

Colicins from E coli bind to TolC and BtuB receptors, once inside they disrupt ion gradients and degrade cell components using enzymes.