Influence of base-pairing in the leader region on in vitro translation of Rous sarcoma virus RNA.

The capacity of the leader region of Rous sarcoma virus (RSV) RNA to act as a regulator of viral protein synthesis was tested in vitro. When DNA/RNA hybrids of sufficient length (greater than 90-100 nucleotides) are created within the leader, synthesis of Pr76gag is inhibited. The inhibition is dependent upon the length of the hybrid rather than its position with the exception that encumberance of the 5'-terminal 33 nucleotides does block translation. These findings demonstrate that physical alteration of the non-coding leader structure directly affects downstream initiation of protein synthesis. It is thus likely that biochemical or physiologic changes in vivo which alter the structure of the leader may affect regulation of viral protein synthesis.