Genome organization of mouse adenovirus type 1 early region 1: A novel transcription map

Abstract

Mouse adenovirus type 1 (MAV-1) genomic DNA from 8.9 to 13.7 map units was sequenced and the early region 1 (E1) transcription map was determined by S1 nuclease, primer extension, and Northern analyses, and cDNA sequencing. The E1 transcription map of MAV-1 had marked dissimilarities from the conserved transcription maps of primate adenovirus E1 s. One major EiA and two E1 B mRNAs were identified in overlapping transcription units. The single E1A mRNA was composed of three exons; the last exon was coincident with the last exon of the E1 B mRNAs. While human adenovirus type 2 (Ad2) utilizes alternate splice donors for the first ElA mRNA exon, MAV-1 does not. Thus, no protein is predicted that would correspond to the Ad2 243 amino acid protein, although MAV-1 can encode a protein similar to the Ad2 289 amino acid protein ( A. 0. Ball, M. E. Williams, and K. R. Spindler, 1988, J. Virol. 62, 3947–3957). Two spliced E1 B mRNAs differed from each other in an intron near the 5′ end of the smaller E1 B mRNA. This smaller mRNA could encode only the 55K E1 B protein, while the larger mRNA could encode both the 21 K and 55K E1 B proteins.