Lecture 23 -- Cell Wall and Protein Inhibition Flashcards
What is the difference between antibiotics and antimicrobials
antibiotics – natural, more complex
antimicrobials – man-made, simple structures
What are the three classes of antimicrobials?
- sulfadrugs
- quinolones
- oxazolidinone
Name the 4 clinically validated targets for antibiotics in bacteria
- inhibition of protein synthesis
- inhibition of DNA/RNA synthesis
- inhibition of cell wall synthesis
- inhibition of folate synthesis
what are the three phases of PG synthesis and what occurs in each phase
cytoplasmic (assembly of monomer units --> Park's nucleotide, lipid I, lipid II) membrane associated (transport to site of polymerization --> lipid cycle) extra cytoplasmic (polymerization --> peptidoglycan)
Which PG inhibiting antibiotic inhibits MurA by blocking the active site?
Fosfomycin
Which PG inhibiting antibiotic acts as a competitive inhibitor for D-ala
D-cycloserine
Which two enzymes does D-cycloserine inhibit
the racemase and the Ddl (d-ala-d-ala ligase)
the transfer of park’s nucleotide to undecaprenyl phosphate, generating lipid I is accomplished through what
MraY/translocase I
What enzyme do nucleoside antibiotics inhibit by competing with park’s nucleotide for its active site
MraY/translocase I
What PG inhibiting antibiotic inhibits the cycle of lipid II being flipped across the membrane and the recycling of undecaprenyl phosphate
works by binding the substrate rather than the enzyme
Bacitracin
Which is involved in crosslinking: transpeptidase or transglycosylate?
transpeptidase
Which is involved in the linking of PG subunits: transpeptidase or transglycosylase?
transglycosylase
Which antibiotic targets transglycosylation and is used as a growth promoter in animal feed?
Moenomycin
Which antibiotics target transpeptidation, are glycopeptides, do not penetrate Gram-negative outer membranes, and bind to pentapeptide tails/D-Ala-D-Ala in PG
Vancomycin and Teichoplanin
Which antibiotics are synthetic compounds that are structural analogs of D-Ala-D-Ala, blocking transpeptidation by irreversibly binding to transpeptidase
Beta-lactams
what amino acid is in the active site of a transpeptidase that acts as a nucleophile for beta-lactams
serine
what are the two hypothetical beta-lactam killing mechanisms and what do they result in
non-lytic mechanism; cell death
lytic mechanism; signal for cell lysis
List the structures of a bacterial ribosome
- small 30s subunit (20 proteins)
- large 50s subunit (30 proteins)
- 2 RNA mcs within large subunit –> 23S and 5S
List the three steps of protein synthesis
Initiation (binding and initial loading), Elongation (continual loading and peptidyl transferase reactions), Exit/termination (hydrolysis of polypeptide and deconstruction of ribosome)
Which antibiotics are characterized by a lactone containing ring, are bacteriostatic, and whose sugar interactions determine binding and specificity
macrolides
which antibiotic has a mechanism of action where it acts as a plug, binding to the 23S section of the ribosome, physically interacting with the peptide chain, allowing the formation of only short peptides as well as the assembly of the 50S subunit
macrolides
Which type of antibiotics bind to the 30S ribosomal subunit without interacting with the protein, preventing the binding of aminoacyl-tRNA which is prematurely released, is largely bacteriostatic
tetracycline
what antibiotics are bacteriocidal at high concentrations, work against gram negatives (not gram positives), are hydrophilic sugars with multiple amino groups
Aminoglycoside
