Bacterial Structure 2&3. 2 Flashcards
The major function of the cytoplasmic membrane is to act as?
*Other two big function?
a permeability barrier, preventing leakage of cytoplasmic metabolites into the environment
*protein anchor and energy conservation
Selective permeability also prevents the diffusion of?
most solutes
The cytoplasmic membrane is constructed of
lipids and proteins that form a bilayer with hydrophilic exteriors and a hydrophobic interior
Phospho-Lipids have both ________ and ________ properties. They play a crucial role in?
hydrophobic (nonpolar) and hydrophilic (polar) properties
* crucial role in membrane
cytoplasmic membrane as permeability barrier? Reason for this barrier?
prevents leakage and function as a gateway for transport of nutrients into and out of cell
*Polar and charged molecules must be transported
cytoplasmic membrane as protein anchor?
site of many proteins involved in transport, bioenergetics, and chemotaxis
cytoplasmic membrane as energy conservation?
site of generation and use of the proton motive force
cytoplasmic membrane anchors protieins such as?
enzymes for catabolic degradation of large macromolecules electron transport system proteins for transport of nutrients structures for chemotaxis (flagella) structures for attachment (pili)
cytoplasmic membrane is composed of ___% and ___%?
75% protein and 25% phospholipid
Transport proteins accumulate molecules into or out of the cell against the?
concentration gradient
*Molecule inside of cell is at a higher concentration than outside cell or vice versa
Simple transporter- are often driven by the? Examples
proton motive force: uniporter, symporter, antiporter
uniporter
one molecule is transported from outside to inside
symporter
two molecules are transported from outside to inside
antiporter
one molecule transported in/another is
transported out
Prokaryotes have at least these 3 types of transporters?
- simple transporters
- phosphotransferase-type transporters
- ABC (ATP-binding cassette) transporters
simple transport
driven by the energy in the proton motive
group translocation
chemical modification of the transported substance driven by phosphoenolpyruvate
ABC transporter (general definition)
periplasmic binding proteins are involved and energy comes from ATP
Phosphotransferase group translocation requires? occurs where?
What happens to nutrients transported in?
*requires energy and phosphate
*occurs at cytoplasmic membrane
*nutrient transported in is modified by phosphorylation, thus a high energy
phosphate group is used
The Phosphotransferase System in E. coli
- A type of group translocation
- The best studied system
- Responsible for transporting glucose, fructose, and mannose
- Five proteins are required
- Energy derived from phosphoenolpyruvate
ABC (ATP-Binding Cassette) transporters contain 3 ______ components
interacting
ABC transporters requires?
energy from either the proton motive force, ATP, or other energy-rich substance
how many different systems identified in prokaryotes for ABC transporters? they display?
contains?
200
- display high substrate specificity
- contain periplasmic binding proteins
what do ABC transporters uptake?
organic compounds (sugars, amino acids) inorganic nutrients (sulfate, phosphate) trace metals
Proteins are exported out of prokaryotic cells through the actions of proteins called ________, which are specific in the types of proteins exported.
translocases
2 systems:
1) Sec translocase system
2) Type III secretion system
translocases are responible for?
exporting proteins through and inserting into prokaryotic membranes
Sec translocase system
exports proteins and inserts integral membrane proteins into the membrane; consists of 7 proteins
Type III secretion system
*Is often a ___ factor?
common in pathogenic bacteria; secreted protein translocated directly into host
•Often a virulence factor
what are the penicillin-binding proteins (PBPs)? They are targets for?
•transpeptidases and carboxypeptidases
* targets for penicillin and other β-lactam antibiotics
Transpeptidation is joining of two?
layers of peptidoglycan via peptides of each layer
Transpeptidation starts with a _________ of one layer and a ______ of the other layer *whereby a diaminopimelic acid is joint to?
starts with a pentapeptide of one layer and a tetra peptide of other layer *diaminopimelic acid is joint to the pentultimate D-alanine and
on D-alanine is lost from the pentapeptide to yield a tetrapeptide on each layer
Peptidoglycan synthesis concludes at
Transpeptidation
what is one of the few remaining drugs for the treatment of multi-resistant G+ infections?
Vancomycin
Vancomycin predominantly binds?
the D-alanyl-Dalanine (D-ala-D-ala) part of the pentapeptide
**penicillin inhibits? ONLY works on growing or dormat bacteria?
transpeptidation aka prevents crosslinkage of cell wall peptidoglycan
*growing bacteria, if dormat than transpeptidation has already happened
what is the first microbial enzyme discovered capable of destroying beta lactam penicillin
Beta-lactamases
Beta-lactamases discovery required the development of? UNFORTUNATLY what happened?
antibiotics resistant to betalactamases such as cephalosporins or compounds capable of inactivating betalactamase or inhibitors
*unfortunatly, new beta-lactamases have evolved that inactivate these second generation antibiotics (so far 890 have been discovered)
what is the new beta-lactamase of mahor concern? (recently discovered, inactivate all generations of antibiotics)
NDM-1, which stands for New Delhi metallo-beta-lactamase-1
Describe NDM-1, which stands for New Delhi metallo-beta-lactamase-1?
encoded on?
hydrolyzes?
what is found on same plasmid?
*A new Beta-Lactamase that has evolved to inactive penicillin antibiotics
encoded on a 180 kb plasmid encoding multiple resistance genes
NDM-1 beta lactamase hydrolyzes penicillins and cephalosporins
Another beta lactamase on the same plasmid inactivates erythromycin,
ciprofloxacin, and chloramphenicol
