Polysomes bypass a 50 nucleotide coding gap less efficiently than monosomes due to attenuation of an unstable 5’ mRNA stem loop stimulator and enhanced drop-off

Ribosome profiling analysis of phage T4 infected E. coli yielded protected mRNA fragments within the normal size range derived from ribosomes stalled at the take-off codon. Ribosomes at this position also yielded some 53 nucleotide fragments, 16 longer. These were due to protection of the nucleotides that form the 5’ stem loop. Ribosome profiling of 'normal' and long protected fragments obtained from T4 infected E.coli or of E.coli with plasmid-borne cassette with the gene 60 sequence