Mappings of adenovirus type 7 cytoplasmic RNA species synthesized early in lytically infected cells and synthesized in transformed cells

Abstract

Early virus-specific RNA synthesized in KB cells infected with adenovirus type 7 and virus-specific RNA synthesized in rat embryo cells (7IJY1-2) transformed by the adenovirus type 7 HindIII-I.J fragment (left-hand 8.1% of the viral genome) have been mapped on the viral genome. About 25% of the viral genome, four discrete regions, two on each strand of the viral genome, are expressed as "early" mRNA. Almost similar regions in the left-hand 8.1% of the viral genome are transcribed both in KB cells at early times after infection and in 7IJY1-2 cells.

E1a regions of the human adenoviruses and of the highly oncogenic simian adenovirus 7 are closely related

“…The largest Ela transcript encodes a polypeptide required for the activation of the other early regions (31, 41). The other two Ela transcripts are dispensable for growth in cell culture, though their conservation in more than one subtype suggests their importance in the viral life cycle in the whole animal (5,11,13,42,61).…”

“…Molecular and genetic analyses demonstrate (i) two separately promoted transcription units designated Ela and Elb (4, 5, 11); (ii) the synthesis of five mature transcripts, three from Ela and two from Elb, differing in each case by the size of the intervening sequence removed (5,11,33); (iii) that the polypeptide encoded by the largest Ela RNA is the sole viral function responsible for the accumulation of RNAs from other adenovirus early genes (31, 41); and (iv) that a function(s) encoded by both Ela and Elb is necessary for transformation of cells in culture (55, 56). The analogous regions of serotypes from the oncogenic subgroups also demonstrate two complex transcription units, utilizing selective removal of intervening sequences to generate transcripts expressing overlapping polypeptides (13,34,42,61). The comparison of the nucleic acid sequences of representatives from the different subgroups has been used to locate those invariant sequences potentially important in the transcriptional regulation of Ela and Elb and also to define highly conserved domains within the encoded polypeptides (57,59).…”

Unique species of mRNA from adenovirus type 7 early region 1 in cells transformed by adenovirus type 7 DNA fragment

“…Thus, we concluded that one spliced mRNA 6.6 MUL (2,310 nucleotides) was composed of two RNA segments and mapped in early region 1B. Because transcriptional direction of early region 1 mRNA's is rightward (32), this early 1B mRNA has its 5' end at map unit 4.6 and its 3' end at 11.4.…”

“…The final concentrations of restriction fragments (Ad7 DNA equivalent) and cytoplasmic RNA were 5 pug/ml and 5 mg/ml, respectively. This condition was about fourfold DNA excess, estimated from the data obtained by saturation hybridization analysis (32). Hybridization mixtures were warmed at 680C for 10 min, allowing the denaturation of DNA, and incubated for 3 h at 53°C, 60C higher than the Tm value (estimated by susceptibility to S1 nuclease; unpublished data).…”