Concerning the thermal stability of E. coli 23S ribosomal RNA.

Total RNA prepared from E. coli by several extraction procedures behaves as a mixture of covalently continuous heat stable 23S, 16S and 4-5S components. 16S rRNA remains heat stable after isolation from such preparations, whereas isolated 23S rRNA is heat labile but becomes heat stable after EDTA treatment. This and other evidence leads to the conclusion that heat lability of purified 23S rRNA is due, not to nuclease contamination of the type observed in earlier studies of the stability of this RNA, but to polyvalent cation catalyzed temperature-dependent scission of phosphodiester bonds. Heat stability of 23S rRNA in total RNA is due to the presence in these preparations of a contaminant which appears to act as a chelator of polyvalent cations. This material is similar or identical to the pyrogenic E. coli lipopolysaccharide described by Westphal and coll.