Regulation of the appearance of cytoplasmic RNAs from region 1 of the adenovirus 2 genome

Abstract

The time-course of appearance of cytoplasmic RNA species coded by the region 9 to 10.7 on the adenovirus 2 genome (early region 1) has been examined using specific DNA probes. Hybridization with restriction endonuclease fragments of viral DNA resolved five cytoplasmic RNAs. A 22 S RNA contains sequences to the right of map position 4.4. One 13 S RNA (13 S L) maps to the left of this site, while an RNA of similar size (13 S f) is transcribed from two separate regions to the right of 4.4. Each 13 S RNA shares 3′ sequences with a distinct 9 S RNA. Sequences in 13S f RNA are also present in the 22 S species. These mapping studies have allowed the identification of probes that can be used to assay each RNA after fractionation by size. During productive infection, each RNA species has a characteristic rate of appearance in the cytoplasm; 22 S and 13 S L RNA accumulate at a constant rate throughout infection. Initially 13 S f RNA appears at a rate substantially lower than the 22 S and 13 S L, RNAs. At late times accumulation of 13 S f RNA is stimulated more than 50-fold, until its appearance exceeds that of the other “early” RNAs. The 9 S RNAs are detected only after viral DNA replication begins. The rate of labeling of each approaches that of its colinear 13 S RNA. The results demonstrate a complex regulatory pattern for region 1 RNAs. Regulatory events must account for: (1) continued synthesis of early RNAs at late times; (2) increased accumulation of 13 S f RNA; (3) the turn on of 9 S synthesis; and (4) balanced rates of appearance of the colinear 13 S and 9 S RNAs at late times.