Selective silencing of antibiotic-tethered ribosomes as a resistance mechanism against aminoglycosides

Understanding antibiotic resistance is essential for combating drug-resistant pathogens. Many bacteria horizontally acquire enzymes that modify antibiotics or their targets to prevent interaction, but when resistance emerges without such modifications, the underlying mechanisms often remain unknown. Here, we describe how mutations in the fusA gene, which encodes translation elongation factor G (EF-G), drive resistance against aminoglycoside antibiotics. fusA resistance mutations, found throughout EF-G, confer resistance without disrupting AGA binding to the ribosome. EF-G resistance variants selectively slow down translocation on aminoglycoside-bound ribosomes until the drug dissociates. This slowdown prevents antibiotic-induced incorporation of consecutive incorrect amino acids (error clusters) into proteins, preserving the proteome and membrane integrity, and limiting drug uptake. In contrast, translocation on antibiotic-free ribosomes remains sufficiently rapid to support near-normal cell growth with or without antibiotic. This previously unrecognized resistance concept—selective silencing of corrupted targets—offers new insights into antibiotic resistance mechanisms beyond traditional paradigms.