Studies on the non-specific binding of ribosomal RNA to Escherichia coli ribosomes

Ribosomal RNA (rRNA) binds to ribosomes which contain small pieces of endogenous messenger RNA, when assayed by sticking to Millipore filters. This association is lost when the messenger RNA is removed by incubation of the ribosomes in buffer containing 10⁻⁴ m-Mg²⁺, but can be recovered by the addition of turnip yellow mosaic virus (TYMV) RNA. TYMV RNA promotes the binding of equal masses of 16 and 23 s rRNA to ribosomes. The incubation in 10⁻⁴ m-Mg²⁺ buffer, which destroys the ability of ribosomes to bind rRNA, increases their ability to bind TYMV RNA fivefold. Free rRNA does not compete with ribosomes for ribosome-binding sites in TYMV RNA. These results suggest that the binding of messenger RNA to free rRNA does not reflect the binding of messenger RNA to ribosomes.