Characterization of Proteins Binding to the ZII Element in the Epstein–Barr Virus BZLF1 Promoter: Transactivation by ATF1

Abstract

Previous studies have shown that the ZII element in the BZLF1 promoter (P1) is responsive to TPA and anti-immunoglobulin induction. In this report, we have studied the DNA/protein complexes formed when ZII is used as a binding site. Twelve distinct DNA/protein complexes were seen in mobility shift experiments using Akata cell nuclear extracts and radiolabeled ZII. Eleven of these complexes were also formed when either BJAB or Raji cell nuclear extracts were used in the binding reaction. Six DNA/protein complexes were affected by mutations in the core TGACATCA motif of ZII which abolish responsiveness to TPA, anti-immunoglobulin treatment, and HHV6 transactivation. The relative sizes of the proteins in the DNA/protein complexes were determined by UV crosslinking. Four distinct specific binding proteins affected by core mutations in ZII were identified as ATFa, ATF1, ATF2, and c-jun. Overexpression of ATF1 in cotransfection experiments caused transactivation of the wild-type P1 promoter but had no effect on a promoter containing a mutant ZII element. An ATF1 mutant with a deleted DNA binding domain failed to transactivate P1. Overexpression of c-jun, ATFa, or ATF2 had no effect on the wild-type or mutant P1 promoter. Our results suggest that ATF1 interacts with the ZII element and may be involved in Epstein-Barr virus reactivation.

Valproic Acid Enhances the Efficacy of Chemotherapy in EBV-Positive Tumors by Increasing Lytic Viral Gene Expression

“…Thus, whether cells contain the latent versus lytic form of viral infection is largely determined by the activity state of the BZLF1 and BRLF1 promoters (Zp and Rp). A number of cellular transcription factors, including Jun, activating transcription factor-2 (ATF-2), Sp1, EGR-1, ZEB-1, MEF-2D, and YY-1, have been shown to regulate the Zp and Rp promoters in vitro (35)(36)(37)(38)(39)(40). Interestingly, in reporter gene assays, the Zp and Rp promoters are essentially silent in most B-cell lines but constitutively active in many epithelial lines, correlating with the propensity of the virus to produce latent infection following infection of B cells and lytic infection following infection of normal epithelial cells.…”

The BRRF1 Early Gene of Epstein-Barr Virus Encodes a Transcription Factor That Enhances Induction of Lytic Infection by BRLF1

“…The Zp CRE site binds ATF-1, ATF-2, c-Jun, and CREB (1,34,37,63). Of these, the phospho-ATF-2/phospho-c-Jun heterodimer may represent the predominant complex responsible for R activation of the Zp CRE site (1).…”

“…7A). Sequences previously shown to be important for Zp activation by a variety of different stimuli include a CRE motif (ZII) (17), which binds CREB, ATF1, ATF2, and c-Jun (1,34,37,63); a series of ZI sites (5,16,17), which bind MEF2D, Sp1, and Sp3 (22,35,36); and ZIII sites, which bind FIG. 5.…”

“…Na activates c-Jun transactivator function. The ZII CRE site of Zp binds the transcription factors CREB, ATF-1, ATF-2, and c-Jun (1,34,37,63), all of which have been shown to activate Zp in reporter assays (1,34,63). Since Na activates Zp through the ZII CRE site, we examined whether Na can activate CREB, ATF-1, ATF-2, or c-Jun fusion proteins linked to the Gal4 DNA binding domain.…”

Virally targeted therapies for EBV-associated malignancies

“…In the case of the BZLF1 promoter (Zp), full activation Toxin expression specific to EBV-containing cells Figure 2 Latent viral promoters that require EBV-encoded gene products in trans, or the oriP replication origin that requires EBNA-1 in trans, can be used to produce cellular toxins specifically in EBV-positive cells requires both a 'ZII' motif (which binds CREB, ATF1, and a c-jun/ATF-2 heterodimer) and several different 'ZI' binding sites, which bind MEF2D as well as Sp1 and Sp3 (Flemington and Speck, 1990;Daibata et al, 1994;Speck et al, 1997;Wang et al, 1997;Adamson et al, 2000;Binne et al, 2002;Bryant and Farrell, 2002;Gruffat et al, 2002). Calcium-induced activation of MEF2D (mediated by calcineurin) and CREB (mediated by CaMKIV/GR) appears to be important for BZLF1 promoter activation following ligation of the B-cell receptor Liu et al, 1997).…”