Limited proteolysis was used to test the interaction of tetracyclines
and some of their derivatives with ribosomes. Proteolysis of the free
ribosomes was compared with that of the ligand-bound ribosomes. The in
teraction of different tetracyclines with ribosomes depends on their c
hemical structure and produces both a protective effect and an increas
ed susceptibility to proteases of some ribosomal proteins in the 30S a
nd 50S subparticles. Most of the proteins affected by tetracycline act
ion are located on the head of the 30S and interface side of the 50S s
ubunits. On the grounds of the obtained data one of the antibiotic-bin
ding regions can be located near the ribosomal peptidyl transferase ce
nter. The effect of possible conformational changes induced by tetracy
clines on the translation process is discussed.