A type VI secretion ADP-ribosyltransferase Rhs toxin selectively modifies charged tRNAThr(GGU) anticodon loops to block ACC codon decoding.

A T6SS-associated ADP-ribosyltransferase toxin from Chromobacterium violaceum selectively modifies charged tRNAThr(GGU) anticodon loops to block ACC codon decoding.

• Why it matters: Understanding how bacterial toxins inhibit protein synthesis reveals mechanisms of interbacterial competition and pathogenicity, filling gaps in knowledge about T6SS effectors and their targets.
• What they did: The study characterized the RhsF toxin’s C-terminal TreThr domain, demonstrating its ADP-ribosyltransferase activity that specifically modifies GGU anticodon loops of charged tRNAThr isoacceptors, using structural modeling, mutagenesis, and in vitro transcription-translation assays.
• The result: TreThr’s targeted modification prevents decoding of threonine ACC codons, inhibiting protein synthesis and providing insights into a precise bacterial toxin strategy for interbacterial antagonism.