Download Bacterial envelope structure and function

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Bacterial cell envelope and
antibiotics efficacy
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The Cell Membrane
(1) selective permeability and
transport of solutes
(2) electron transport and oxidative
phosphorylation in aerobic
species
(3) excretion of hydrolytic
exoenzymes
(4)
bearing the enzymes and carrier
molecules that function in the
biosynthesis of DNA, cell wall
polymers, and membrane lipids
(5) bearing the receptors and other
proteins of the chemotactic and
other sensory transduction systems
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Permeability and transport
uniport
Active transport
Ion-coupled
transport
symport
ABC transport
antiport
Simple diffusion
transports
Passive transport
Facilitated
diffusion
Group
translocation
Vectorial
metabolism
Special transport
processes
Fe transport
Channel proteins
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Group translocation
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Excretion of hydrolytic exoenzymes and
pathogenicity proteins
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Excretion of hydrolytic exoenzymes and
pathogenicity proteins
α-hemolysin
E coli
adenylyl cyclase
Bordetella pertussis
Type l
Elastase
Type ll
phospholipase C
Pseudomonas
aeruginosa
exotoxin A
Excretion protein
Type lll
Type lV
protein–DNA
complexes
Agrobacterium
tumefaciens
pertussis toxin
B pertussis
interleukin-8–inducing
factor
H pylori
IgA protease
Neisseria
gonorrhoeae
vacuolating cytotoxin
Helicobacter pylori
Type V
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Special Components of Gram-Negative
and Gram- positive Cell Walls
 Gram-negative:
 Gram-positive:
 1. Outer membrane
 1.Teichoic acid
 2. Lipopolysaccharide (LPS)
 2.Lipoteichoic acid
 3.Lipoprotein
 3.Teichoronic acid
 4.The periplasmic space
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Special Components of Gram-Positive Cell
Walls
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Special Components of Gram-Negative
Cell Walls
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The Peptidoglycan Layer
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Biosynthetic functions : Synthesis of
Cell Wall Peptidoglycan
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D-Ala-D-Ala synthesis
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INHIBITION OF CELL WALL SYNTHESIS
penicillin's
cephalosporin's
β-lactam drugs
monobactams
carpabenem
antibiotics
glycopeptide
Vancomycin
other
Cycloserine
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The mimicry of beta-lactam antibiotics to
acyl-D-alanyl-D-alanine (D-Ala-D-Ala)
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Mechanism of action β-lactam
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The model of beta-lactamase
induction in Gram-negative bacteria
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Beta-lactamase
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vancomycin

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cycloserine
 is an amino acid derivative with
an unusual structure
 As a cyclic analogue of Dalanine, cycloserine acts against
two crucial enzymes important in
the cytosolic stages of
peptidoglycan synthesis: alanine
racemase (Alr) and D-alanine:Dalanine ligase (Ddl)
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Bacitracin
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Lysozyme
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INHIBITION/ALTERATION OF CELL
MEMBRANE FUNCTION
detergent-like
• Polymyxins
permit rapid diffusion of specific cations
through the membrane
• Daptomycin
specifically interfere with biosynthetic
functions of the cytoplasmic membranes
• Novobiocin
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Polymyxins
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Daptomycin
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Antimicrobial peptides
 are part of the innate immune
response found among all classes
of life
 These peptides are potent,
broad spectrum antibiotics
 Are cationic and bind to acidic
bacterial membrane
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AMPs mechanism of action
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