Ribosome antibiotic

Auerbach T, Bashan A, Yonath A. Ribosomal antibiotics structural basis for resistance, synergism and selectivity. Trends Biotechnol. 2004 22 570-576. 

Anti-ribosomal antibiotics are enzyme inhibitors, and the ones that are dinically useful inhibit bacterial ribosomes far more effectively than they inhibit eukaryotic ribosomes. Many enzyme inhibitors exert their effects by binding to the active site of enzymes and thereby prevent the binding of substrates. Others block enzyme function by inhibiting conformational changes essential for enzyme activity. Anti-ribosomal antibiotics are unexceptional in this regard. They bind to the sites on both subunits to which tRNA also binds. Some block the interactions of substrates with the ribosome. Others block the tunnel and thereby prevent the nascent peptide from extending. 

Keywords ribosome antibiotics RNA drug design molecular modeling crystallography docking QSAR Macrolides Oxazolidinones aminoglycosides molecular properties... 

Table 1 Crystal structures of ribosome antibiotic complexes in Figure 2...

Lastly, bacteriocins, a large set of ribosomal antibiotic peptides are produced by numerous strains of bacteria associated with marine invertebrates and vertebrates. Bacteriocin-producing bacteria mainly belong to the genera Aeromonas, Alteromonas, Cytophaga-Flavohacterium-Bacteroides group, Pseudoalteromonas and Vibrio. Bacteriocins and bacteriocin-like inhibitory substances (BUS) could be used as probiotics in the aquaculture industry (Desriac et al, 2010). 

Resistance to Lincomycin. Resistance to lincomycin is developed slowly, and is usually caused by modification of 23S ribosomal RNA, which leads to co-resistance to macroHde, lincosaminide, and streptogramin B antibiotics (25). Inactivation of lincomycin by clinical isolates of strains of Staphjlococcus aureus and Staphjlococcus haemoljticus, though retention of sensitivity to macroHdes (see Antibiotics, macrolides) and streptogramins (see Antibiotics, peptides), has been found to be the consequence of the conversion of the antibiotic into its 3-(5 -adenylate) (26). 

Antibiotic A201A. Antibiotic A201A (23), produced by S. capreolus is an /V -dimethyladenine nucleoside stmcturaHy similar to puromycin (19). Compound (23) which contains an aromatic acid and monosaccharide residues (1,4), inhibits the incorporation of amino acids into proteins but has no effect on RNA or DNA synthesis. Compound (23) does not accept polypeptides as does (19), and does appear to block formation of the initiation complex of the SOS subunit. It may block formation of a puromycin-reactive ribosome. 

It has been known for some time that tetracyclines are accumulated by bacteria and prevent bacterial protein synthesis (Fig. 4). Furthermore, inhibition of protein synthesis is responsible for the bacteriostatic effect (85). Inhibition of protein synthesis results primarily from dismption of codon-anticodon interaction between tRNA and mRNA so that binding of aminoacyl-tRNA to the ribosomal acceptor (A) site is prevented (85). The precise mechanism is not understood. However, inhibition is likely to result from interaction of the tetracyclines with the 30S ribosomal subunit because these antibiotics are known to bind strongly to a single site on the 30S subunit (85). 

Tetracycline and its derivative doxycycline are antibiotics widely used in the treatment of bacterial infections. They also exert an antimalarial activity. Tetracyclines inhibit the binding of aminoacyl-tRNA to the ribosome during protein synthesis. 

Lactam Antibiotics Ribosomal Protein Synthesis Inhibitors... 

Macrolides are a group of antibiotics, produced in nature by many actinomycetes strains, that are composed of a 12- to 16-membered lactone ring, to which one or more sugar substituents is attached. They target the peptidyl transferase center on the 50S ribosomal subunit and function primarily by interfering with movement of the nascent peptide away from the active site and into the exit tunnel. 

The ribosome is the cellular target of a large and chemically diverse group of antibiotics. The antibiotic binding sites are clustered at functional centers of the ribosome and the majority are composed exclusively of RNA. The drugs interfere with the positioning and movement of substrates, products and ribosomal components that are essential for protein synthesis. 

Ribosomal Protein Synthesis Inhibitors. Figure 5 Nucleotides at the binding sites of chloramphenicol, erythromycin and clindamycin at the peptidyl transferase center. The nucleotides that are within 4.4 A of the antibiotics chloramphenicol, erythromycin and clindamycin in 50S-antibiotic complexes are indicated with the letters C, E, and L, respectively, on the secondary structure of the peptidyl transferase loop region of 23S rRNA (the sequence shown is that of E. coll). The sites of drug resistance in one or more peptidyl transferase antibiotics due to base changes (solid circles) and lack of modification (solid square) are indicated. Nucleotides that display altered chemical reactivity in the presence of one or more peptidyl transferase antibiotics are boxed. 

---