The binding of kasugamycin to the Escherichia coli ribosomes

The binding of kasugamycin to the E. coli ribosomes has been demonstrated by equilibrium dialysis. Kasugamycin binds to the 70S ribosomes in a molar ratio of 1:1. The association constant is approximately 6 X 10(-4) M-1. The antibiotic binds to the 30S subunit as well as to 70S ribosomes, but only slightly to the 50S subunit. The binding of kasugamycin is not significantly affected by the presence of other aminolgycoside antibiotics: streptomycin, kanamycin. or gentamicin. Kasugamycin does not bind to ribosomes derived from a kasugamycin-resistant mutant, ksgC.