30S ribosomes

T. thermophilus 30S ribosome Cognate tRNA-mRNA IIBM 3.31 1 

Kinetics of fMet-tRNA binding to 30S ribosomal subunit Inhibition of ribosomal binding of fMet-tRNA by an antibiotic may reduce the level of initiation complex formed at equilibrium. However, if the effect of the inhibitor consists mainly of slowing down the binding reaction, its effect may appear less dramatic after a relatively long incubation time. For this 

Alteration in binding site Streptomycin Protein S12 component of 30S ribosomal subunit determines sensitivity or resistance 

Figure 3.1A. Interaction of aminoglycosides with the acceptor site of the 30S ribosome. Schematic representation of (A) paromomycin and (B) streptomycin interactions with the 16S rRNA and ribosomal protein SI2.

Chang, F.N., and Flaks, J.C. (1972) Specific cross-linking of Escherichia coli 30S ribosomal subunit. J. Mol. Biol. 68, 177. 

Several hundred macromolecules, which are needed for protein biosynthesis—i.e., 30 ribosomes, more than 100 protein fac- 

Carter AP, Clemons WM, Brodersen DE et al (2000) Functional insights from the structure of the 30S ribosomal subunit and its interactions with antibiotics. Nature 407 340-348 

Czworkowski, J., Odom, O.W., and Hardesty, B. (1991) Study of the topology of messenger RNA bound to the 30S ribosomal subunit of Escherichia coli. Biochemistry 30, 4821. 

Majumdar, Z., Hickerson, R., Noller, H. and Clegg, R. (2005). Measurements of internal distance changes of the 30S ribosome using FRET with multiple donor-acceptor pairs Quantitative spectroscopic methods. J. Mol. Biol. 351, 1123-45. 

Samaha, R.R., Joseph, S., O Brien, B., O Brien, T.W., and Noller, H.F. (1999) Site-directed hydroxyl radical probing of 30S ribosomal subunits by using Fe(II) tethered to an interruption in the 16S rRNA chain. PNAS 96, 366. 

Brodersen DE, Clemons WM, Carter AP et al (2000) The structural basis for the action of the antibiotics tetracycline, pactamycin and hygromycin B on the 30S ribosomal subunit. Cell 103 1143-1154 

An example of the results that can be obtained by rapid filtration is shown in Fig. 12.5C, which illustrates the inhibition of fMet-tRNA binding to 022 mRNA-programmed 30S ribosomal subunit by increasing concentrations of GE811112 (Brandi et al., 2006b). 

Brandi, L., Fabbretti, A., Di Stefano, M., Lazzarini, A., Abbondi, M., and Gualerzi, C. O. (2006a). Characterization of GE82832, a peptide translocation inhibitor interacting with bacterial 30S ribosomal subunits, /v Al l 12, 1262—1270. 

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). 

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