Action of T₁ Ribonuclease on Escherichia coli Ribosomes and their Subunits

1 A study of sensitivity to T1 ribonuclease of the 16 S and 23 S RNAs within the 30 S and 50 S subunits and the 70 S ribosomes from Escherichia coli has been performed using sucrose gradient sedimentation. 2 The sensitivity of 23 S RNA within the 50 S subunits is greater than that of 16 S RNA within the 30 S subunits. 3 After action of T1 ribonuclease on both 30 S and 50 S subunits, under conditions which would lead to total hydrolysis of the free RNAs, the persistence of protected RNA fragments of large size is observed. 4 A much less significant degradation of 16 S and 23 S RNAs is observed, when T1 ribonuclease action is performed under the same conditions upon the 70 S ribosomes, instead of 30 and 50 S subunits; this supports the existence of regions in both RNAs involved in the association of the two subunits.