Antibiotics +cell division

Question 1

Types of antibiotics

Answer 1

Penicillins, cephalosporins,B-lactams, increased activity, Macrolides,Tetracyclines, Lincosamides,Quinolones, Trimethoprim-sulfamethoxazole,other

Question 2

Targets

Answer 2

Beta-lactams,penicillin+deriv-Glycosylase,Transpeptidase enz.
Vancomycin-D-ala,cross-linking,complestatin +corbomycin-autolysin activity,Ramoplanin +Fosformycin,Production of UDP-G/or UDP M,Bacitarcin-bactoprenol recycling

Question 3

Transglycosylation +transpeptidation

Answer 3

Catalyzes formation of glycan chains
Cross-linking reaction
Amide bonds between peptide strands

Question 4

Transglycosylation +transpeptidation examples

Answer 4

Gram-negative bacteria (E-coli)-cross-links form between D-Ala +DAP-direct bond
Gram-positive bacteria (S. Aureus)-cross-links form between D-Ala +L-Lys (penta-glycine interbridge)

Question 5

B Lactam +glycopeptide antibiotics

Answer 5

Binds to pencillin-binding proteins-both gram + and -
Glycosylase+Transpeptidase-bond can’t form

Question 6

Polypeptide antibiotics

Answer 6

Bactroprenol ferries PGL monomer from cytoplasm to periplasm
binds to bactroprenol-inhibits recycling

Question 7

Bacterial cell division

Answer 7

Division by binary fission-no sexual life cycle, clonal reproduction -asexually
Daughter chromosomes partitioned to opposite ends
Division septum forms-divide cells in 2

Question 8

MreB: cell elongation

Answer 8

-rod shaped cell
-coil along the bacterial cell
cell elongation
recruits enzymes for PGL synthesis

Question 9

Chromosome separation

Answer 9

Separation of chromosomes
Dysfunctional MreB inhibits chromosome segregation
Mutant-stays long

Question 10

Formation of division septum

Answer 10

Min proteins-finds the middle-locate
Nucleoid occlusion (NO) position division site at midcell-No factor,SlmA,protects the nucleoid from z ring-protects DNA
Fts proteins-FtsZ assembles into ring structure-FtsZ-Divisome-Septum

Question 11

Fts proteins are required for divisome

Answer 11

Scaffold for division septum
FtsZ-forms z ring (present-FtsA +ZipA), initiates formation of division septum-membrane_wall
ZipA-recruits FtsZ+FtsA-binds:attach z-ring to cell membrane
Other Fts proteins-Ftsl=trans-peptidase

Question 12

Regulating FtsZ polymerization

Answer 12

Z ring formation
SlmA protein-Barrier
Accumulates over nucleoids
prevents from FtsZ from cutting DNA
Z ring doesn’t form over nucleoid-forms between

Question 13

Min Proteins determine divisome location

Answer 13

Loss of Min system is not lethal-leads to frequent polar divisions
Chromosomeless minicells-small that don’t contain chromosomes do not divide

Question 14

Min proteins restrict divisome to midcell

Answer 14

Min C-blocks FtsZ polymerization +z-ring formation from cutting, anywhere
Min D-Attaches MinC +MinE to the cell membrane and activates min C-requires ATP
Min E-Located middle-ish of cell, pushes mincd to the ends of cell,allows FtsZ polymerization +Z-ring formation

Question 15

Middle positioning of Z ring

Answer 15

Dog version
MinE-german shepherd around center (FtsZ)-you to protect you from chihuahua-MinCD

Question 16

MinE is the determinant of the middle

Answer 16

Oscillates mid-cell (ish)-every 20 seconds
prevents MinCD localization at mid-cell,allows accumulation of FtsZ at mid-cell,Z-ring,division septum

Question 17

Min CD are division inhibitors

Answer 17

Inhibit FtsZ accumulation
prevent formation of division septum
During cell growth minCD oscillates through cell-between two ends

Question 18

Cell division in E coli: Min proteins

Answer 18

Min E localizes to the middle of the cell
Pushes MinCD to cell poles, prevents CD from polymerizing the mid cell
MInCd oscillates from end to end of the cell
prevents FtsZ polymerization at poles
Z-ring forms midcell