A 5′-terminal phosphate is required for stable ternary complex formation and translation of leaderless mRNA in Escherichia coli

Primer extension inhibition (toeprint) analysis of 70S ribosome binding to LL cI-lacZ mRNA with a 5′-triphosphate (lanes 1–4), a 5′-monophosphate (lanes 5–8), or a 5′-hydroxyl (lanes 9–12). Lanes 1, 5, and 9 exclude 70S ribosomes, and lanes 2, 6, and 10 exclude tRNA^fMet (1 μM when included). (Lanes 3,7,11) 30S subunit concentration (88 nM) is twofold higher than mRNA (44 nM) concentration. (Lanes 2,4,6,8,10,12) 70S ribosome concentration (264 nM) is sixfold higher than mRNA concentration. The position of the toeprint signal is identified by an arrow.