Role of ribosome recycling factor (RRF) in translational coupling

RNA phage GA coat and lysis protein expression are translationally coupled through an overlapping termination and initiation codon UAAUG, Essential fo r this coupling are the proximity of the termination codon of the upstream coat gene to the initiation codon of the lysis gene (either a <3 nucleotide separation or physical closeness through a possible hairpin structure) but not the Shine-Dalgarno sequence. This suggests that the ribosomes completi ng the coat gene translation are exclusively responsible for translation of the lysis gene. Inactivation of ribosome recycling factor (RRF), which nor mally releases ribosomes at the termination codon, did not influence the ex pression of the reporter gene fused to the lysis gene. This suggests the po ssibility that RRF may not release ribosomes from the junction UAAUG, Howev er, RRF is essential for correct ribosomal recognition of the AUG codon as the initiation site for the lysis gene.