Ribosomes streptomycin action

Inhibition of protein synthesis by aminoglycoside antibiotics, especially by streptomycin, is bactericidal (rev.46)). The antibiotic binds to the smaller ribosomal subunit and leads to the formation of abortive initiation complexes of ribosomes, streptomycin and amino acyl tRNA which progressively trap ribosomes in the form of such biologically irreversible complexes. When protein synthesis is prematurely terminated by puromycin and ribosomes are thus made available for reinitiation of de novo protein biosynthesis, the bactericidal action of streptomycin is accelerated47). Destruction of ribosomes under the influence of primaquine operationally also results in non-occurrence of protein synthesis and in a marked bactericidal effect48, 49 ... 

As mentioned in the introductory paragraph, the mechanism of aminoglycoside (streptomycin) action toward bacteria was found to involve ribosome binding. In their landmark paper, Davies and coworkers showed that... 

The answer is d. (Hardman, pp 1105-1108.) The bactericidal activity of streptomycin and other aminoglycosides involves a direct action on the 305 ribosomal subunit, the site at which these agents both inhibit protein... 

A satisfactory correlation has been found to exist between sensitivity of archaeal ribosomes to certain antibiotics (streptomycin, erythromycin, a-sarcin) and possession of the specific structural motifs that are involved in antibiotic action. 

In addition, analogous experiments were carried out with puromycin (0.03 milligram per milliliter, as dihydrochloride), under conditions of repression or physiological derepression. In this case, no effect on the differential rates of formation of the transaminase, argininosuccinase, or acetylornithinase was observed. These negative findings with puromycin, on the one hand, indicate that the results with the 30 S inhibitors streptomycin and tetracycline are not nonspecific consequences of ribosomal inhibition or lowered growth rate and, on the other hand, would seem to reflect the differences in mode of action between these two inhibitors and puromycin. (A review of the mode of action of ribosomal inhibitors has recently been prepared by Pestka [104].)... 

In 1962 Speyer, Basilio and I proved the validity of a hypothesis by Spotts and Stanier according to which the difference between streptomycin-sensitive, resistant and dependent E. coli. resides in the structure of their ribosomes. We established that streptomycin inhibits poly(U) directed polyphenylalanine synthesis in a fractionated cell-free protein synthesizing system only if the ribosomes in the system are taken from streptomycin-sensitive cells. These results indicated that in sensitive cells streptomycin inteiieres with ribosome action. As subsequent studies revealed, streptomycin is only one among many antibiotics whose site of action is the ribosome. 

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