Mechanism of action of habekacin, a novel amino acid-containing aminoglycoside antibiotic.

The molecular basis for activity of habekacin was studied by using Escherichia coli Q-13. Electron microscopic studies revealed that numerous blebs, derived from the outer membrane, were formed on cells treated with habekacin. Cytoplasmic contents leaked into the lumina of blebs, and the membrane of some enlarged blebs was disrupted. In a cell-free system, habekacin interfered with polypeptide synthesis, caused codon misreading, and inhibited translocation of N-acetylphenylalanyl-tRNA from the acceptor site to the donor site on ribosomes. [3H]habekacin bound to both 50S and 30S ribosomal subunits. The current experiments indicated that the mechanism of action of habekacin is similar to that of 2-deoxystreptamine-containing aminoglycoside antibiotics such as dibekacin, kanamycin, gentamicin, and related substances. The relationship of membrane damage to inhibition of ribosomal functions remains to be determined.