Rolyadenylic acid [poly(A)] sequences associated with measles virus intracellular ribonucleic acid (RNA) species

Abstract

The kinetics of 3H-uridine incorporation into measles-infected Vero cells demonstrated that maximum virus-specific RNA synthesis occurred between 16 and 20 h after infection. Sedimentation analysis on sucrose gradients revealed the presence of four species of RNA having sedimentation coefficients 4S, 12 to 26S, 28 to 36S and 50S. Annealing studies showed that RNA sedimenting in the 12 to 36S regions was 100% complementary in base sequence to nucleocapsid 50S RNA, and at least 96% of the 50S genomic RNA was transcribed during virus replication. Polynucleotide binding experiments ane ribonuclease treatment indicated that poly(A) sequences were associated with the intracellular 12 to 26S, 28 to 36S and 50S RNAs. Denaturation of intracellular 50S RNA followed by sucrose gadient centrifugation demonstrated that this was a mixture of genomic 50S and heterogeneous RNAs which sedimented at 4 to 40S. The genomic RNA did not contain poly(A) sequences, and these are presumably associated with the heterogeneously sedimenting RNAs. The size of poly(A) sequences present on the 12 to 36S RNAs was estimated to be in the range of 70 to 140 nucleotides. Treatment of the 12 to 36S RNAs and their poly(A) sequences with polynucleotide phosphorylase indicated that the poly(A) was located on the 3' end of the RNAs, but that under the experimental conditions used this was protected by the secondary structure of the molecules.