The nucleotide sequence of SV40 DNA was determined, and the sequence was correlated with known genes of the virus and with the structure of viral messenger RNA's. There is a limited overlap of the coding regions for structural proteins and a complex pattern of leader sequences at the 5' end of late messenger RNA. The sequence of the early region is consistent with recent proposals that the large early polypeptide of SV40 is encoded in noncontinguous segments of DNA.

No abstract

No abstract

We have examined the relationship between sequence-specific DNA-binding proteins that activate transcription of ElA-inducible adenovirus early promoters. Factors previously referred to as E4F1 and E2A-EF bind to the E4 and E2A promoters, respectively. We demonstrate here that E4F1 and E2A-EF have identical DNA-binding specificity. Moreover, E4F1 and E2A-EF both activate transcription of the E4 and E2A promoters in vitro. These findings demonstrate that E4F1 and E2A-EF are the same factor, which we have designated activating transcription factor, or ATF. In addition to the E4 and E2A promoters, ATF binds to an important functional element of the ElA-inducible E3 promoter. Interaction of a common activator protein, ATF, with multiple ElA-inducible early viral promoters, suggests a significant role for ATF in ElA-mediated transcriptional activation.The EIA gene of adenovirus produces closely related 13S and 12S mRNAs that encode nuclear-localized phosphoproteins with diverse transcriptional regulatory properties (1-3). The EMA 13S gene product coordinately activates a set of viral early genes (EIA, EIB, E2A, E3, and E4) during a productive infection of permissive human cells (4-7). The ElA 12S gene product encodes a transcriptional repression function that appears to act through transcriptional enhancer elements (8-10). In addition to regulating viral transcription, ElA activates or represses transcription of a limited number of cellular genes (11,12), and activates polymerase III-dependent promoters (for review, see ref. E4 and E3 transcription (18, 19). For the EIB promoter (22) and the cellular /-globin promoter (23), the "TATA" box has been implicated as an ElA-responsive promoter element. Thus activation of a variety of ElA-inducible promoters appears to involve different cellular factors and may occur through divergent pathways, ultimately linked by ElA. Two independent studies have identified additional factors that interact with early viral promoters. A factor referred to as E4F1 binds to the E4 promoter and also interacts with the EIA, E2A, and E3 promoters (18). Similarly, a factor referred to as E2A-EF binds to the E2A, EIA, E3, and E4 promoters (17). We show here that E4F1 and E2A-EF have the same DNA-binding specificity and that both factors activate transcription of the E4 and E2A promoters in vitro. These results demonstrate that E4F1 and E2A-EF are the same factor, which we refer to as ATF, for activating transcription factor. In addition to the E4 and E2A promoters, ATF interacts with an important functional element of the adenovirus E3 promoter. The interaction of ATF with multiple ElA-inducible promoters suggests a significant role for ATF in E1A-mediated transcriptional activation. MATERIALS AND METHODSPlasmids. pE4WT contains the adenovirus type 5 genome between map units 100 and 89, including the entire E4 gene cloned into pBR322 between the EcoRI and Pvu II sites.