Size analysis and relationship of murine leukemia virus-specific mRNA's: evidence for transposition of sequences during synthesis and processing of subgenomic mRNA

Abstract

Virus-specific mRNA from purified polyribosomes of mouse cells infected with Moloney murine leukemia virus (M-MuLV) was analyzed by electrophoresis in agarose gels, followed by hybridization of gel slices with M-MuLV-specific complementary DNA (cDNA). The size resolution of the gels was better than that of sucrose gradients used in previous analyses, and two virus-specific mRNA9s of 38S and 24S were detected. The 24S virus-specific mRNA is predominantly derived from the 39 half of the M-MuLV genome, since cDNAgag(pol) (complementary to the 59 half of the M-MuLV genome) could not efficiently anneal with this mRNA. However, sequences complementary to cDNA synthesized from the extreme 59 end of M-MuLV 38S RNA (cDNA 59) are present in the 24S virus-specific mRNA, since cDNA 59 (130 nucleotides) efficiently annealed with this mRNA. The annealing of cDNA 59 was not due to repetition of 59 terminal nucleotide sequences at the 39 end of M-MuLV 38S RNA, since smaller cDNA 59 molecules (60 to 70 nucleotides), which likely lack the terminal repetition, also efficiently annealed with the 24S mRNA. The sequences in 24S virus-specific mRNA recognized by cDNA 59 are not present in 39 fragments of virion RNA that are the same length. Therefore, it appears that RNA sequences from the extreme 59 end of the M-MuLV genome may be transposed to sequences from the 39 half of the M-MuLV 38S RNA during synthesis and processing of the 24S virus-specific mRNA. These results may indicate a phenomenon similar to the RNA splicing processes that occur during synthesis of adenovirus and papovavirus mRNA9s. Images