Repression of the alpha0 gene by ICP4 during a productive herpes simplex virus infection.
AUTOR(ES)
Lium, E K
RESUMO
During a productive infection by herpes simplex virus type 1 (HSV-1), ICP4, the major regulatory protein encoded by the alpha4 gene, binds to its transcription initiation site and represses the accumulation of alpha4 RNA. Evidence suggests that the degree of repression by ICP4 is a function of the absolute distance of an ICP4 binding site 3' from a TATA box. However, repression of HSV-1 gene expression by ICP4 through binding sites located 5' of TATA boxes, as in the case of the alpha0 gene, has not been adequately addressed. To this end, recombinant alpha0 promoters with various arrays of ICP4 binding sites flanking the alpha0 TATA box were constructed and recombined into the HSV-1 genome. Our results demonstrate the following. (i) Destruction of the endogenous alphaO ICP4 binding site, located 5' of the TATA box, results in derepression of alpha0 protein and RNA accumulation in infected Vero cells. (ii) The degree of alpha0 derepression is equivalent to that reported for the alpha4 gene following destruction of the ICP4 binding site at the alpha4 mRNA cap site in HSV-1. (iii) Introduction of an ICP4 binding site at the alpha0 mRNA cap site represses the accumulation of alpha0 RNA greater than threefold relative to the wild type. (iv) Changes in the abundance of alpha0 protein and RNA in infected cells do not affect replication or growth of HSV-1 in tissue culture. Our findings are consistent with the conclusion that alpha0 transcription is repressed by ICP4. These results demonstrate that repression by ICP4 can occur through binding sites located 5' of virus gene TATA boxes in HSV-1. Thus, models addressing repression of HSV-1 gene expression by ICP4 should incorporate the role of binding sites located 5', as well as 3', of virus gene TATA boxes.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=190222Documentos Relacionados
- Herpes simplex virus immediate-early proteins ICP0 and ICP4 activate the endogenous human alpha-globin gene in nonerythroid cells.
- The RR1 gene of herpes simplex virus type 1 is uniquely trans activated by ICP0 during infection.
- Association of herpes simplex virus regulatory protein ICP4 with sequences spanning the ICP4 gene transcription initiation site.
- DNA binding by the herpes simplex virus type 1 ICP4 protein is necessary for efficient down regulation of the ICP0 promoter.
- The herpes simplex virus type 1 alpha protein ICP27 can act as a trans-repressor or a trans-activator in combination with ICP4 and ICP0.