An adenovirus E4 gene product trans-activates E2 transcription and stimulates stable E2F binding through a direct association with E2F.
AUTOR(ES)
Neill, S D
RESUMO
The adenovirus E4 gene encodes a trans-activating function that can stimulate the E2 promoter. E2 promoter sequences required for E4 trans-activation are identical to those required for E1A trans-activation, and these principally are the E2 promoter binding factor (E2F) binding sites. Furthermore, full activation of E2F DNA binding activity requires both E1A and E4 action. Analysis of a series of mutant E4 viruses identifies open reading frame (orf) 6/7 of the E4 transcription unit as that required for activation of E2F binding activity. In addition, the assay of various E4 cDNAs demonstrates that the E4 orf 6/7 also is responsible for the trans-activation of E2 transcription. Translation of the E4 orf 6/7 mRNA, but not a control mRNA, in a reticulocyte extract generates an activity that can stimulate cooperative binding of E2F in vitro, consistent with recent in vivo assays that demonstrate a role for the E4 gene in E2F stable complex formation. This stimulation is due to a direct interaction of the E4 protein with E2F since an antibody that recognizes the E4 orf 6/7 polypeptide detects this E4 protein in the E2F-DNA complex. We conclude that the E4 orf 6/7 product interacts with the E2F factor altering binding to allow formation of a stable complex that results in a stimulation of transcription.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=53614Documentos Relacionados
- The adenovirus E4 gene, in addition to the E1A gene, is important for trans-activation of E2 transcription and for E2F activation.
- The human papillomavirus type 16 E7 gene product interacts with and trans-activates the AP1 family of transcription factors.
- Human T cell lymphotropic virus type I Tax protein trans-activates interleukin 15 gene transcription through an NF-κB site
- The hepatitis B virus X-gene product trans-activates both RNA polymerase II and III promoters.
- Activation of the E2F transcription factor in adenovirus-infected cells involves E1A-dependent stimulation of DNA-binding activity and induction of cooperative binding mediated by an E4 gene product.