Cytosine at the 3′ -Termini of Reovirus Genome and in vitro mRNA

Abstract

DOUBLE stranded RNA isolated from purified reoviruses consists of a mixture of ten different genome fragments¹. We have shown that a unique 5′-terminal sequence, ppGpYp (Y = pyrimidine), is present in all ten segments, indicating that they exist as distinct entities within the virion (A. K. S. and A. J. S., manuscript submitted for publication). The duplex segments are transcribed in vitro by a virion-associated RNA polymerase and the resulting single stranded mRNAs also terminate with 5′-ppGpYp². In view of the similarity between the 5′ ends of reovirus genome RNA and in vitro mRNA, it was of interest to compare their 3′-termini. We now report that both types of RNA have cytosine as the 3′-terminal base.